project no.: ses6-ct-2003-502812 bio-pro new...
TRANSCRIPT
Project no.: SES6-CT-2003-502812
Project acronym:
BIO-PRO
Project full name: NEW BURNER TECHNOLOGIES FOR LOW GRADE BIOFUELS TO SUPPLY CLEAN ENERGY FOR
PROCESSES IN BIOREFINERIES
Instrument type: SPECIFIC TARGETED RESEARCH OR INNOVATION PROJECT
Priority name:
SUSTAINABLE ENERGY SYSTEMS
Publishable final activity report Period covered: from 1.12.03 to 28.02.07 Date of preparation: 19/05/2007 Start date of project: 1.12.2003 Duration: 39 months Project coordinator name: Dr. Roland Berger Project coordinator organisation name:
University of Stuttgart, Institute of Process Engineering and Power Plant Technology (USTUTT)
Final
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CONTENT
1 PROJECT EXECUTION...................................................................................... 3
1.1 Project objectives.......................................................................................................... 3
1.2 Contractors involved.................................................................................................... 3
1.3 Work performed and end results................................................................................ 3 1.3.1 Characterisation of biorefinery processes and bio fuels (WP 1) ............................ 3
1.3.1.1 Market study................................................................................................... 3 1.3.1.2 Fuel analysis ................................................................................................... 5 1.3.1.3 Study on fuel pre-treatment.......................................................................... 11
1.3.2 Burner development – gaseous and liquid fuels (WP 2) ...................................... 11 1.3.2.1 Burner development – GL-burner (based on FLOX)................................... 11 1.3.2.2 Burner development – GL-burner (based on COSTAIR) ............................ 18 1.3.2.3 Application of advanced NOx reduction technology for FLOX.................. 21
1.3.3 Process development unit of pre-gasifier for solid fuels (WP 3) ......................... 22 1.3.3.1 Burner development – S-burner (FLOX/fixed-bed gasifier)........................ 22 1.3.3.2 Burner development – S-burner (COSTAIR/BioSwirl)............................... 28 1.3.3.3 Burner development –S-burner (advanced NOx-reduction) ........................ 33
1.3.4 Development of the control system (WP 4) ......................................................... 36 1.3.4.1 Development of an on-line fuel gas analyser (OFGA) ................................ 36 1.3.4.2 Guidelines for control strategies of flameless oxidation G-L burners in different boiler control configurations ......................................................................... 37 1.3.4.3 Computational Fluid Dynamics modelling and simulation of a typical flameless oxidation burner (FLOXTM G-L burner delivered by WS Wärmeprozesstechnik) ................................................................................................. 39 1.3.4.4 Combustion experiments on low-medium calorific value gas targeted at minimizing emissions to acceptable levels .................................................................. 40 1.3.4.5 Design and optimisation of an integrated controller for the S-burner.......... 45 1.3.4.6 Controller optimization ................................................................................ 47 1.3.4.7 Set up of industrial controllers ..................................................................... 50
1.3.5 Industrial testing of prototype burners (WP 5)..................................................... 53 1.3.5.1 Industrial testing of first FLOX-prototype burner at FW test site................ 53 1.3.5.2 Industrial testing of second FLOX-prototype burner at ZAMER test site ... 59 1.3.5.3 Additional industrial test of FLOX-prototype flare for landfill gases ......... 61
1.3.6 Socio-Economic evaluation and dissemination, technical exploitation (WP 6) .. 63 1.3.6.1 Life Cycle Assessment of the two developed prototypes ............................ 63 1.3.6.2 Market Evaluation ........................................................................................ 79
2 DISSEMINATION AND USE............................................................................. 84
2.1 Publishable results...................................................................................................... 84
2.2 Overview of results’ exploitation and use potential ................................................ 88
2.3 Innovation related activities ...................................................................................... 89
2.4 Report for engaging with the public......................................................................... 90
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1 Project execution
1.1 Project objectives The project aims on developing new combustion technologies for bio-residues. Innovative combustion technologies like flameless oxidation (FLOX®) and continuous air staging (COSTAIR) will be enhanced by re-burning and co-firing in order to meet this goal. Two basic types of BIO-PRO burners will be developed to meet this goal:
• A pilot burner for gas and liquid fuels; • A pilot burner for solid fuels applying a pre-gasification step for the solids without gas
cooling.
The technology to be developed shall be able to self adjust to different fuel qualities (fuel moisture 10-50%). For emissions of the investigated fuels the upper limit for CO will be 30 mg/m³ (currently 50 mg/m³ are typical) and NOx will be reduced by 50% (starting point for dry wood chips in available combustion systems = 210 mg/m³).
1.2 Contractors involved The consortium of the project consists of nine partners from seven countries. Universities, research centres as well as a SME and an industrial partner are represented in the consortium. The following table provides an overview on the involved contractors.
Role No. Name Short Name Country Universities
CO 1 University of Stuttgart – Insitute of Process Engineering and Power Plant Technology
USTUTT Germany
CR 6 Technical University of Delft TUD Netherlands CR 9 Energy research centre, University of Ulster UU UK
SME CR 3 WS Wärmeprozesstechnik WS Germany
Industry CR 4 Foster Wheeler FW Finland
Research centres CR 2 Termiska Processer AB TPS Sweden CR 5 Foundation of Appropriate Technology and Social Ecology FATSE Switzerland CR 7 Instytut Energetyki - Insitute of Power Engineering IEN Poland CR 8 Gaswärme-Insitut GWI Germany
1.3 Work performed and end results
1.3.1 Characterisation of biorefinery processes and bio fuels (WP 1)
1.3.1.1 Market study The first approach to the market study was to collect data about reference fuels from all the Member States. The idea was to obtain this data by contacting organizations and companies that are engaged in the field of biomass and ask for completing and returning a simple template.
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This first approach appeared to be unsuccessful. There were two reasons of this lack of success. The first one was connected with personnel problems of one of the involved partners and the second one with the lack of response from the organizations to which the templates were sent. This situation forced IEn to search the data in public databases and publications. The information collected in this way was not sufficient to prepare the market study. In this situation IEn was forced to develop the descriptive method of approach individually to particular branch. Finally the quantitative data of particular branches was collected. The next step was to perform analyses referring to waste generation of all selected branches. This data compensated the lacks in statistical data. This kind of approach was much more laborious than predicted in the beginning of the work. Because of this fact, after consultations with the partners it was decided to limit the area of market study. On the second technical project meeting in Trosa, Sweden responsibility for collecting data for particular countries were distributed among three partners. The distribution was as follows: · IEn – Poland · TPS – Scandinavian countries · USTUTT – Germany, Switzerland In Table 1 the collected data from Switzerland, Germany and Poland are shown. Data from Scandinavia were to general to present them here.
Table 1 Data of wastes from biorefineries delivered by partners
Switzerland
[1000t] Germany [1000t]
Poland [1000t]
Brewing industry 71,82 2651 86 Distillery industry 27,2 720 37,5
Oil industry 80,33 2025 43 Potato industry 2784 1540
Grain and animal feed industry 8,44 1437 450 Sugar industry 142 24858 600
Poultry industry 215 Fruit and vegatable industry 36,2 286 385
Dairy insustry 986 8298 2,3 Paper and cellulose industry 30,3 500 1000
Planting 606 9300 6000 Livestock
Meet procesing industry 306 2100 630 Sawmills 597 5000 4680
Woodwork 500 105 Furniture industry 208 3000 1050 Plywood industry 4,26 955
Forestry 1260 16600 1600 Tannery industry 39,2
Leather clothes industry 24,3
Based on the collected data and own knowledge of the market, the partners have chosen the most promising biorefinery from the project point of view, which were assessed on the base of assumptions that are shown below:
• There are a substantial number of plants or it is expected that the market will grow in the future.
• The biorefinery produces residues which can be utilized by BIO-PRO burners.
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• The biorefinery needs energy, preferably thermal energy which can be supplied by BIO-PRO burners.
Most promising BIO-PRO bio-refineries producing solid residues has been selected: Breweries, pulp and paper industry, saw mills, sugar/bio-ethanol industry. Another promising fuel that arose during the discussion of the project partners was landfill gas. Table 2 shows the potential of the landfill gas in the European countries.
Table 2 Landfill gas generation in Europe 2003
1000TOE Germany 955,00 Estonia 3,00 Greece 36,00 Spain 257,00 France 190,00 Ireland 25,00
Italy 255,00 Latvia 3,00
Lithuania 2,00 Luxembourg 4,00
Hungary 5,00 Netherlands 128,00
Austria 43,00 Poland 39,00
Portugal 1,00 Slovenia 6,00 Slovakia 4,00 Finland 20,00 Sweden 112,00
United Kingdom 1 129,00 Norway 26,00
The development of landfill gas to energy schemes is expanding rapidly throughout the EU. Environmental measures designed to reduce greenhouse gas emissions are promoting the collection and use of landfill. This situation has led to a fast increasing of installed capacity. This uptake rate is likely to continue for several years as more and more landfills will be installed with collection systems. Once the gas is collected, the preferred option is to burn it to reduce its greenhouse gas potential. Since the landfill gas has to be combusted, most landfill operators would prefer to derive some economic benefit from the combustion by generating electricity for export and sale. Wide spectrum of issues influencing application of the solid residues and landfill methane for energy production was analysed, including: availability of information, price, investment risk, environmental implications, financial support, and infrastructure constrains.
1.3.1.2 Fuel analysis Results of the market study have shown that availability of bio-refinery wastes could be limited. On other hand, EU Member States policies supporting renewable electricity production promote use of other biomass sources which are also relevant to BIO-PRO project objectives. From the technical point of view biomass feedstock for the gasifier will not affect so much technologies being developed within project, providing that gas quality is comparable which those obtained from solid residuals.
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Such emerging biomass sources are energy crops. Analysis of such fuels were performed by IEn in he second year of the project. The samples were purchased from the Institute of Soil Science and Plant Cultivation. At IEn laboratory the analyses of these fuels were carried out and repeated several times for each sample. Results of investigations are shown in Figure 1 to Figure 3. Moisture content in all samples varied from 1.17% (II r. Gigantea pr.5 from Grabów) to 8.33% (Miskant 115 from Osiny). The biggest percentage moisture content was observed in different genotypes of Miskant from Grabów and Osiny as well. Ash content varied from 1.17% (5.10 Sida Łod. – 2 batch from Osiny) to 3.85% (Miskant 105 from Osiny). All types of biomasses had small amount of ash (at the average several times less than hard coal). Heat of combustion relating to dry and ash-free state varied from 19158 kJ/kg (Klon 1023 II r./4 from Grabów) to 20984 kJ/kg (I r. Gl. Mozga trzcinowa). Volatiles content was the smallest for 5.10 Sida Łod. from Osiny – 67.75% and the biggest for II r. Gigantea pr.5 from Grabów – 75.16%. All types of biomasses are characterized by huge amount of volatiles, at the average 70% in raw state. It is more or less two times more than in case of coals, applied in power industry. Bulk density varied from 120 kg/m3 (pył drzewny from Przemyśl) to 300 kg/m3 (10 pl II r. Klon 1047) and was smaller than for coals. In Figure 1 to Figure 3 are shown results of studies in form of graphs. For all samples the beginning of outgassing starts in range 200-300°C (Figure 1). In temperature 300°C volatiles content varied from 5.78% to 39.07%. This range was changing with temperature and it reached its minimum at 500°C. Afterwards it began to grow again and in 800°C varied from 70% to 78%. The fastest outgassing was observed for Miskantus 7, 115, and 117 from Osiny. In case of Miskantus 115 and 117 but from Grabów degassing was slower. It is worth to mention that above 400°C rate of outgassing was rapidly slowing down and volatiles content was growing from 62% to 70% adequately to range 400-800°C for majority of biomasses. Samples like Gigantea II r. pr.5 from Grabów, Klon 1052 II r./2 from Grabów and Pl-9 1023 II r. from Osiny demonstrated dynamic out gassing even above 400°C, and volatiles content reached maximum at 800°C in range 75-78% (relating to dry state). In case of coal process of out gassing proceeded in two stages where were two different rate of this process (first range 400-600°C and second 600-800°C).
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Osiny 5.10 Sida Łod Grabów II r. Gigantea pr 5 Osiny II r. Pl-9 1023 Osiny I r. gl. le
Osiny I r. gl. lek. Topinambur Grabów Klon 1052 II r./2 Grabów Miskantus 1/w Grabów Misan
Grabów Miskant 117 Osiny Miskant Giganteus Osiny Miskant 7 Osiny Miskant
Osiny Miskant 115 Osiny Miskant 117 Dolna Odra Węgiel kamienny Przemyśl Pył d
Figure 1 Volatiles content (relating to raw state) in different temperatures of outgassing
Very interesting are results of heat combustion studies of created cokes and evaluation of volatiles heat combustion (Fig. 2 and Fig. 3).
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Osiny 5.10 Sida Łod Grabów II r. Gigantea pr 5 Osiny II r. Pl-9 1023Osiny I r. gl. lek. Mozga Trzc. Osiny I r. gl. lek. Topinambur Grabów Klon 1052 II r./2Grabów Miskantus 1/w Grabów Misant 115 Grabów Miskant 117Osiny Miskant Giganteus Osiny Miskant 7 Osiny Miskant 105Osiny Miskant 115 Osiny Miskant 117 Dolna Odra Węgiel kamiennyPrzemyśl Pył drzewny
Figure 2 Cokes heat of combustion created in different temperatures of outgassing
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Osiny 5.10 Sida Łod Grabów II r. Gigantea pr 5 Osiny II r. Pl-9 1023Osiny I r. gl. lek. Mozga Trzc. Osiny I r. gl. lek. Topinambur Grabów Klon 1052 II rGrabów Miskantus 1/w Grabów Misant 115 Grabów Miskant 117Osiny Miskant Giganteus Osiny Miskant 7 Osiny Miskant 105Osiny Miskant 115 Osiny Miskant 117 Dolna Odra Węgiel kamPrzemyśl Pył drzew ny
Figure 3 Volatiles heat of combustion created in different temperatures of outgassing
Volatiles heat of combustion, created in range 400-800°C is similar for all types of samples except Mozga Trzcinowa I r. gl. Lek. from Osiny, Pl-9 1023 II r. from Osiny. Apart from these two samples which had a little bit bigger heat of combustion, rest reached level 14500 kJ/kg. On the contrary their cokes heat of combustion was the lowest from all biomasses in all investigated ranges of temperatures. It is probably caused by high ash content in Mozga trzcinowa. Cokes heat of combustion for different samples is changeable. In case of char (which means cokes, created in temperature above 500°C) was in range: from 24000 to 32600 kJ/kg (characteristic value for pure coal). To sum up the more ash in fuel, the coke heat of combustion is lower.
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./2
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./3
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Zaw artość popiołu w stanie surow ym Ciepło spalania karbonizatu pow stałego w temperaturze 600 st.C
Figure 4 Comparison of ash content in samples and coke heat of combustion created in temperature 600 °C
Ash content in raw state Heat of coke created in 6000C
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However more detailed analysis proved that this regularity is not always truth (see Figure 4
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). For example Miskant 117 from Grabów (fourth position from right size of the graph) with 1.42% of ash content, has high coke heat of combustion 32104 kJ/kg. Sample Pl-12 II r. 1054 from Osiny (sixth position from left side of the graph) which has circa the same ash content
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shows lower coke heat of combustion, about 2300 kJ/kg. At this point of experiments it was hard to explain such behavior. Higher hydrogen content in char in Mskantus from Grabów or the influence of inorganic substance (ash) on assigning heat of combustion can cause this effect. It is easy to find more such differences between samples. Summary
Physicochemical analysis was conducted in different temperatures. Results show similarity between samples: low ash content, high volatiles content, average heat of combustion at the level 18000 kJ/kg. It is hard to predict behavior of each sample because the differences in pyrolysis character depend on type of biomass and temperature of process. Such situation is good observed in low temperatures where huge variations of volatiles composition (hydrocarbons, tars) are taking place. As a result of this fact it is being obtained different volatiles heat of combustion. With growing temperature of process, this differences start to vanish but created cokes start to differ from each other in domain of heat of combustion also.
1.3.1.3 Study on fuel pre-treatment The objective of this work was to show how moist wood fuels can be made technically and economically available for small scale heat generation where dry fuels so far has been the only option. The work has included both theoretical and experimental work. The idea was to study different handling and drying concepts where a drying is integrated in the process without the need for expensive equipment. This would enable the use of a larger range of fuels for environmentally friendly and reliable heat production in small scale below 10 MW. A case study was made for a 3 MW heat producing facility at a saw mill. The study started with a literature review on different techniques for pre-treatment and drying. Different technical concepts, such as flash driers and drum driers, have been compared with respect to combustion performance, plant availability and plant economics. From the results of the theoretical study, experiments were done were different drying concepts were integrated and tested in a commercial plant at a saw mill. The work is very important for this type of industry were different types of residues are produced that are potential fuels for heat generation in small scale. Most combustion equipment is designed for specific fuel types and one of the most important combustion parameter in biomass combustion is fuel moisture. If there was an effective and cheap system that could pre-treat fuels with different fuel moisture content with waste heat, then this would made it possible for the industry to use more of its own residues for heat production. In many cases this would mean that biomass fuels can replace fossil fuels to a larger extent with better economy and less environmental impact.
1.3.2 Burner development – gaseous and liquid fuels (WP 2)
1.3.2.1 Burner development – GL-burner (based on FLOX) Gaseous FLOX-burner
By choosing the FLOX®-combustor, a mock-up for an atmospheric FLOX-burner prepared for later developments for micro-turbine applications, turned out to be the perfect choice. This new design premixes air and fuel some millimetres before entering the combustion chamber. Following advantages are to be pointed out:
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1. Through the venturi-effect, pressure less fuel can be burned. 2. Through the multi-nozzle design the boundary layer surface between new gases
entering the combustion chamber and the hot exhausts is enlarged. This effect results in a strongly increased power density of up to 30 [MW/m3 bar] and therefore very compact design.
3. The same effect reduces the minimum gas velocity necessary to provide the FLOX-typical complete mixing
4. Through the premixing of fuel and air, the burner can be used both as start-up (flame-) burner and FLOX-burner. For the first, the velocities and therefore the power has to be reduced drastically. However the start-up burner velocities are still by far high enough to prevent flash-backs into the gas-premixing nozzles for all gaseous fuels (not tested/calculated with hydrogen).
However the same design has from a scientific point of view the disadvantage, that the change from flame to FLOX mode is not clearly visible and defined but rather a slight increase of the low-NOx combustion quality. From a technical point of view this has now effect upon performance but the economical advantage by saving the installation of a separate start-up burner. With several sets of different nozzle geometries and combustion chamber outlays with and without a inner guiding tube, the performance of the FLOX-Combustor has been tested with the reference fuel G1 (natural gas):
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Figure 5 Performance of FLOX-Combustor according NOx-emissions with reference fuel G1: The curves of equivalent emissions are plotted in relation to the theoretic adiabatic combustion temperature (defined by the air excess ratio) and the effective combustion chamber temperature. The last was defined by the respective highest value measured at six positions within the combustion chamber. With LCV-fuel, equivalent NOx-emissions can be achieved at lower air ratios.
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adiabat. temp. [oC]
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Figure 6 NOx-emissions plotted in relation to air-excess-ratio (displayed as adiabatic temperature) and nozzle velocity. The visible boundary at around 65 m/s between FLOX and flame mode has later been confirmed by research of DLR on a pressurized FLOX-Combustor for gas turbines.
Very low caloric values
The project objective for cold, gaseous Low-Caloric-Value fuels (LCV) was a stable combustion at 4 MJ/m3 fuel (1/9 of reference fuel G1). To avoid the need for enormous quantities of N2 and CO2 in bottles (>10 times more than fuel gas), the test rig was modified so that the own exhausts could be reused to dilute the fuel-gas. A 200 kW exhaust/air heat exchanger was applied to cool the exhaust to values close to ambient temperature (Figure 7). Soon after first trials, it turned out that the compact FLOX-combustor can reach values beyond this target. However the power density had to be reduced to gain residence time and the insulation had to be enhanced. Finally in early 2005, first tests could be performed with an enlarged and thick insulated combustion chamber. Additionally the exhaust heat recuperation was simulated by applying an electric preheating for the combustion air. With 2.1 ± 0.1 MJ/m3 heat value of the fuel (1.35 MJ/m3 in the total volume flow including combustion air), a sensational value could be achieved (Figure 8). Due to the lower combustion temperatures and the further enhanced “flameless” quality, the NOx and CO emission where very low (NOx below 5 mg/m3
n @ 3% O2). However the power density was reduced to values around 3 MW/m3 bar. However for one phenomenon discovered, no explanation could be established until the end of the project: The effect of the slowly moving reaction zone (Figure 9). Below a heat value of 2.5 MJ/m3 the combustion zone within the insulated combustion zone suddenly started to move downstream slowly. Keeping in mind, that the residence time of the gas molecules is shorter than a quarter of a second, the moving of the zone in with velocities of one centimetre per minute or similar is not explicable. Furthermore, the effect is completely reversible. Further research has to cover this phenomenon.
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Figure 7 View of the prototype burner test rig at FATSE laboratories. With this installation cold exhaust gas could be used to deluted the fuel and therefore simulating low-caloric-value-fuels. 1) FLOX® combustor (without insulation), 2) gas probe, 3) heated line of gas analytics, 4) hot exhaust transfer, 5) exhaust cooler, 6) exhaust suction control ventilator, 7) exhaust line, 8) flue gas recirculation (FGR) line with throttle valve, 9) combustion air inlet, 10) condensate outlet, 11) combustion air ventilator, 12) massflow measurement of combustion air and inert gas, 13) frequency controller for ventilator, 14) combustion air oxygen probe, 15) air preheater, 16) preheater bypass valve, 17) nozzle drag pressure gauge, 18) magnetic valves on fuel line, 19) ignition transformer, 20) control and safery unit.
LCV tests @ 75 m/s nozzle velocity (tr = 0.23s)
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Figure 8 Typical results from tests with diluted fuel (G1 + inert gas from exhaust). NOx- and CO-emissions are plotted in relation to the heat value of the fuel at constant total volume flow. Remark that the scale for NOx-emissions is cut at 10 mg/m3
n. 2.2 MJ/m3 equals 6% of a typical heat value of natural gas.
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Figure 9 Phenomenon of slowly moving combustion zone: the temperature at the centre of the bottom of the combustion chamber and the exhaust on top are plotted in relation to the heat value changing over the time. Depending on calculation method and mass flow measurement, the heat value of the diluted fuel differs slightly (blue and pink curves).
FLOX burner for liquid biofuels
In PM 25, the tests with the last design of the burner for liquid fuels where completed. Eight design iterations between PM 12 and 24 where necessary to finally reach a shape, where all demands are covered:
Figure 10 Cut through the bio-liquid FLOX burner. It consists of: (1) a water cooled oil spray nozzle, (2) ignitor, (3) guiding tube, (4) air chamber and nozzles, (5) exhaust.
Content 16
Figure 11 Peripheral installation fort he rape-seed-oil burner, consisting of control unit, fuel pump and mass flow measurement of each fuel and combustion air
Figure 12 Rape-seed-oil FLOX burner at 12.5 kW operation
To start, the guiding tube is to be moved downstream to block exhaust recirculation. In this configuration, the burner can be started either with light fuel oil or gas premixed with air. After heating up the guiding tube (which has a low thermal capacity and therefore heats up quickly), it is shifted back to standard position (as drawn), the burner shifts to FLOX-mode and is then ready for the bio-fuel. In this work package, the reference fuel was light fuel oil (EL). However as the viscosity (15 times higher for rape-seed-oil) and the ignitability temperature (320°C for rape-seed-oil and 77°C for light fuel oil) differ so much from raw bio-fuels, the tests where performed directly with rape-seed-oil. The burner reached and underbid the project goals:
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atio
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FATSE laboratories / 12.01.2006 / Zu, ms rape seed oil, FLOX burner Mark VIII
methane rape seed oil
Figure 13 Test data plot from Mark VIII design. Please remark that the standardisation (% of O2 in
echaust) changes while switching from methane to rape-seed-oil
Rape seed oil burner Mark VIII
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23
15
FATSE Laboratories / 12.01.2006 / Zu, ms
Figure 14 NOx and CO emissions in relation to the air excess ratio
The NOx-emission showed reproducible results between 23 and 40 mg/m3
n @ 6% O2 (Project objective: 50 mg/m3
n @ 6% O2). With the CO-emissions, the project goals could be reached with 15 to 22 mg/m3
n @ 6% O2 at air excess ratio λ = 1.3 to 1.4. However the CO-emissions are an effect of a slightly too small combustion chamber and therefore increase with the power. Due to the fact, that most of the combustion process takes place within the guiding tube, the power density is with 18 to 22 MW/m3bar probably too high for oil burners. This can be considered accordingly in a up-scaling process. In the sense of bio-refinery application, further tests where performed with a waste liquid from bio-diesel production: The liquid is an emulsion of glycerol, traces of bio-diesel, water and the catalyst (2% NaOH). Although the theoretic heat value should be high enough for an autothermal combustion, the fuel could only be co-fired. According observations, the different densities and viscosities of the ingredients, the fuel nozzle swirl seemed to have disintegrated the fuel into solid drops of burnables and a spray of water. However a scale up applying
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simpler spray technology could solve these problems as well. Applying up to 15 bars fuel pressure and additional water (to reduce the viscosity) the test fuel started to produce soap-like paste. The catalyst remained as a white ash in the burners exhaust. With the mentioned tests the liquid-burner development was completed.
1.3.2.2 Burner development – GL-burner (based on COSTAIR) COSTAIR combustion system
The best COSTAIR burner configuration to utilize low calorific gas efficiently was set-up by numerical simulations and modified by experiments. The following conditions were applied: Tair ≈ 20 °C; Tgas ≈ 550 °C; p ≈ patm. At the tests two different gas mixtures were used. The first gas mixture consisted of the components: H2 =14 Vol.-%; CO = 21 Vol.-%; CO2 = 10 Vol.-%; N2 = 55 Vol.-%. The measurements showed for this mixture, NOX and CO emission values lower than the limit values aimed at the Bio-Pro project. The NOX value in the dry flue gas (@ 3 % O2) was below 15 ppm and the value for CO below 10 ppm (see Figure 15). A stable and almost non-pulsating flame could be ensured at the same time. The combustion took place in the region around the air distributor as seen in Figure 16. The second gas mixture contained additionally to the components of the first one a very low ammonia amount (NH3 = 0,1 Vol.-%; H2 = 14 Vol.-%; CO = 21 Vol.-%; CO2 = 10 Vol -%; N2 = 54,9 Vol.-%). The measuring results for this gas mixture showed low CO emission, but high NOX values (NOx=250-300 ppm). This means that nitrogen bound in the fuel converts in high grade to NO.
0123456789
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Figure 15 CO and NOX Emissions of the adopted burner without NH3 in the gas mixture
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Figure 16 Photography of the flame
The pressures for gas and air before entering the burner were very low at all experiments done. Typically values were 25 mbar for gas pressure und 10 mbar for air pressure.
Scale-up of prototype COSTAIR burner
GWI scaled up the COSTAIR burner for BioSwirl gasifier from 30 kW to 1MW by use the following scale-up criteria:
Inlet velocity = constant
wgas,GWI = wgas,TPS
Ratios of air to gas impulse = constant
( ) ( )
( ) GWIgasTPSgasTPSair
GWIairTPSrdistributoTPSairTPSgasTPSgas
Im
Idmd
,
.
,2
,
,.2
,,2
,,
⋅⋅
⋅⋅⋅=
ρ
ρ
&
&
From the results of both scale-up criteria the suitable gas diameter for TPS test plant has been chosen. The determination of the air distributor length has been set-up based on experiences owned by GWI. The arrangement of air holes on the air distributor was similar to the optimised GWI conical air distributor. The air holes geometries guarantee similar opening ratio, i.e. similar pressure drop, as at GWI. This way ensures approximately the same inlet impulse ratios air to gas as at GWI. GWI carried out several CFD simulations on the COSTAIR burner for BioSwirl gasifier with different air distributor lengths to find out the effect on NOx emission. The combustion behavior can be expressed well by the temperature distributions shown in Figure 17 for the three different variants. Results confirmed that CO emission values at outlet of combustion chamber are going significantly down with longer air distributor, but unfortunately, NO could not be considered in the calculations as the pdf combustion model of FLUENT version 6.2 did not include the calculation of NO generated by N-Fuel.
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Figure 17 Temperature distributions at symmetry plains for different air distributor lengths GWI sent the final design configurations of the scaled up conical air distributor for 1 MW to partner TPS. TPS carried out the experiments on its gasifier using biomass gasification gases. Further CFD simulations were made to find out the influence of the flue gas admixing into the combustion air. Three amounts of flue gas recirculation rates have been considered. The Table below shows the main results achieved.
Conclusions from numerical simulations: the flue gas admixing to the secondary air leads to similar effect as a longer air distributor. The combustion improvement is at the same level.
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1.3.2.3 Application of advanced NOx reduction technology for FLOX According the project objectives, advanced NOx-emission reduction strategies have to be developed and tested for G- and L-burners. However a screening of all project relevant fuels has shown that fuel-based NOx-emissions are a topic which, with exception of BtL (L4), is only of concern for the solid fuels. Table 3N-content and expected NOx-emissions of liquid and gaseous fuels
Fuel
nitrogen content [mg/kg fuel]
resulting fuel based NOx if completely converted
[mg/mn3 @ 6% O2]*
typical burner emissions (NOx)
[mg/mn3 @ 6% O2]*
Natural Gas - - 80
Light Fuel Oil 140 36 120
Rapeseed Oil 76** 20 100
* according dry exhaust volumes ** measured by Bayerisches Landesamt für Umweltschutz
Table 4 N-content and expected NOx-emissions of wood fuels
Fuel
nitrogen content [% weight]
if completely converted to NOx
[mg/mn3 @ 13% O2]
If according measured conversion factors
[mg/mn3 @ 13% O2]
typical burner emissions (NOx)
[mg/mn3 @ 13% O2]
Mixed wood chips 0.18 % 1 250 3 40 4 200 1
Beech wood 0.2 % 1 275 3 40 4 200 2
Spruce wood 0.07 % 1 96 3 28 4 200 2
Chip boards 2.9 % 1 4’000 3 200 4 400 1 1 Keller R., Nussbaumer T.; Primärseitige NOx-Minderung mittels Luftstufung bei der Holzverbrennung, ETH Zürich 1994 2 Gaegauf C., Maquat Y., Schmid M.; Experience from several field testing campaigns, FATSE Langenbruck, 2000-2005 3 Gaegauf C., Schmid M.; Calculated from dry exhaust volume flows, FATSE Langenbruck, 2006-01-06 4 Schmid M.; Calculated from conversion factors for stepped combustion, FATSE Langenbruck, 2005 However the scientific discussion was held since 1994 about the conversion factors of fuel nitrogen to NOx. With combustion tests in a 79% Argon / 21% O2 atmosphere, our institute tested the conversion of fuel-based nitrogen. However the above figures supported the earlier made decision to continue the advanced NOx reduction strategies with the S-burner. In the last reports (PM24), the preliminary tests of the reduction potentials with 350 mg/m3 NO injected into natural gas (G1, modified) where reported under G-L-burners. The report will be continued under WP3. However the integration of the design into the S-burners was parallel done at FATSE and USTUTT. Due to logistics and efficiency of progress, a 20 kW wood pellets gasifier was built up additionally at FATSE. This additional effort was possible through the EUREKA Project No. 3414, which asked for such installations at FATSE for non-wood-pellets combustion research.
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1.3.3 Process development unit of pre-gasifier for solid fuels (WP 3)
1.3.3.1 Burner development – S-burner (FLOX/fixed-bed gasifier)
Design and installation of the pre-gasifier
For the tests with a fixed-bed pre-gasifier a dual chamber firing system for wood chips was purchased and installed in the first project year. The dual chamber firing system consists of a degassing chamber that is connected by a flame pipe with the boiler. For the tests within the project the degassing chamber will be operated as a pre-gasifier. That means the stoichiometric ratio in the degassing chamber will further be reduced to obtain a low calorific value gas. This gas will subsequently be burned in the subsequent combustion chamber (reference case) and the BIO-PRO burner, respectively. Commissioning and testing of the pre-gasifier
Tests with the fixed-bed pre-gasifier were carried out with the reference fuels wood chips, wood pellets, residues of flour mills (wheat husks) and residues of oil mills (rape cake). The tests were carried out at different lambda values in the pre-gasifier. The total lambda was kept constant. The combustion of wood pellets and wood chips in the original system was stable. Both CO and NOx emissions were in the range of 100 mg/m3 (@ 13 % O2) for wood pellets under standard operation conditions (operation as dual chamber furnace). For wood chips CO emissions are in the range of about 100 to 200 mg/Nm3 and NOx emissions between 150 and 280 mg/m3. The operation of the pre-gasifier at lower lambda was counterbalanced with adjustments of the secondary air to keep a constant overall lambda. The operation of the pre-gasifier at lower lambda results for both tested fuels in higher CO emissions. Obviously the gas produced in the pre-gasifier was not completely burned although the secondary air amount was increased to keep a constant overall lambda. The higher amount of secondary air leads to an increase of the flame length. Visual observations of the flame showed that with increased secondary air amount the flame hits the back wall of the combustion chamber and the flame is quenched. Higher CO emissions are the result. Higher NOx emissions (230-280 mg/Nm3) were observed for the tests with wood chips at lambda lower than 0.4 in the pre-gasification step. For higher lambda (λ > 0.4) the NOx emissions were in range of 150-190 mg/Nm3. For the combustion of wheat husks under standard settings CO emissions are below 30 mg/Nm3 and NOx emissions between 460 and 500 mg/Nm3. Similar observations are made as in previous tests regarding CO emissions at reduced lambda in the pre-gasifier. NOx emissions are reduced at these conditions (320 and 340 mg/Nm3), but this is mostly related to the higher CO level that enhanced the NO reduction. A stable combustion of rape cake in the test facility could not be achieved. Due to the small particle size of the fuel the fuel bed on the grate was very dense and the air did not homogeneously pass the fuel bed. Thus, the emissions of CO and hydrocarbons were very high and even soot were observed. A complete burnout was not established. Design of S-burner for fixed-bed pre-gasifier based on FLOX
To design a burner for the fixed bed pre-gasifier the boundary conditions had to be determined. Therefore, probe measurements were carried out to determine the composition and temperature of the produced gas at the end of the pre-gasifier. The tests were carried out with wood pellets and wood chips. The measurements of the gas composition show that only a very low-grade gas can be produced in the pre-gasifier without any further adjustments of the pre-gasifier design. The
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produced gas changes with time and probably with location in the gasifier as variations in fuel feeding and air supply cannot totally be prevented. The gas quality can slightly be improved by reducing lambda in the pre-gasifier, but only to a small extent. However, the gas temperature is very high (950-1000 °C) and thus the LCV gas could easily be ignited in a downstream burner. The specific air demand for such a LCV gas is very low. Based on these results the S-burner for the fixed bed pre-gasifier was designed and constructed in co-operation with FATSE and WS. According to the successful tests with the adapted FLOX-burner in workpackage 2 the concept of a two-nozzle-ring burner, one ring for air and one ring for gas supply was used and adapted to the test plant. The finally design is shown in Figure 18. The FLOX burner was integrated to the fixed-bed pre-gasifier in November 2005. The FLOX-burner was installed in place of the flame pipe (Figure 19).
Figure 18 Design of FLOX-burner for pre-gasifier test plant (left) and manufactured FLOX-burner (right).
Figure 19 Test rig with integrated FLOX-burner and external flue gas recirculation
Tests with the integrated S-burner based on FLOX
Four different fuels (wood chips, rape cake pellets, wheat husks, wheat pellets) were tested within the combined pre-gasifier/FLOX-burner test ring. Three different burners were tested. The first burner was equipped with 8 mm air nozzles and the second one with 10 mm air nozzles. The third burner had a simplified combustion chamber design. During the first test period wood chips and rape cake pellets were tested. The burner with 8 mm air nozzles can be operated for both fuels down to a lambda of about 1.5. At lower lambda the combustion of the
Location of gas sampling
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LCV gases is incomplete and results in high CO emissions. During the second test period wood chips, rape cake pellets and wheat husks were tested. The air nozzles diameter was changed to 10 mm. The changed burner can be operated for wood chips and rape cake pellets down to lambda of about 1.17 (Figure 20) and for wheat husks down to 1.24 (4 % excess oxygen). CO emissions levels were improved and values below 30 mg/m3 can be achieved with the burner for all tested fuels. NOx emissions depend on the nitrogen content in the fuel. For wood chips with a nitrogen content below 0.3 wt-% NOx emissions were about 150 mg/m3, for wheat husks with 2.3 wt-% N the emissions were at optimal conditions between 480 and 550 mg/m3 and for rape cake pellets with 5.1 wt-% N the lowest NOx emissions achieved were between 830 and 1060 mg/m3.
Wood chips - FLOX
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2nd burner - CO: ~ 30 mg/m3 2nd burner - NOx: ~ 150 mg/m31st burner - CO: ~ 75 mg/m3 1st burner - NOx: ~ 140 mg/m3
Figure 20 Comparison of first and second burner regarding CO and NOx emissions
In order to simplify the burner design first CFD simulations were carried out to investigate possible simpler designs. The design study by CFD simulation has shown that the gas nozzle plate is essential to initiate a recirculation zone and thus a homogenous temperature distribution. On the other hand the conjunction at the end of the previous burners has no additional stabilising effect on the recirculation zone. Therefore, a simple cylindrical combustion chamber is sufficient. During the third test period wood chips, rape cape pellets and wheat pellets (2 % limestone added) were tested. The gas and air nozzle design of the burner is the same as for the second test period, but the combustion chamber was simplified due to the above mentioned reasons. Furthermore, tests were carried out applying an external flue gas recirculation (Figure 19). Similar to the previous test results a very good burn-out is again achieved with the rebuilt FLOX-burner and CO emissions are mostly below 30 mg/m3 (@ 13 % O2). NOx emissions of wood chips and rape cake pellets are similar to the previous tests. NOx emissions for the tests with wheat pellets were in the range of 630 to 820 mg/m3. An external flue gas recirculation (FGR) did not have an influence on the NOx emissions for all tested fuels (Figure 21).
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NOx - wood chips NOx - wood chips (FGR)NOx - wheat pellets NOx - wheat pellets (FGR)NOx- rape cake pellets NOx- rape cake pellets (FGR)
Figure 21 Overview of NOx emissions related to total lambda for tests with and without flue gas
recirculation (FGR) using wood chips, wheat pellets and rape cake pellets (third test period)
Comparison of conventional burner and FLOX-burner
In Table 5 the ranges of CO and NOx emissions under optimal conditions for flame and FLOX-combustion for the different fuels are summarized. Tests with the original burner were carried out with wood chips, wheat husks and rape cake. For the tests with wood chips and wheat husks the CO emissions were normally above 100 to 200 mg/m3 and at excess oxygen below 7 vol-% the combustion becomes incomplete. A stable combustion of rape cake was not possible to achieve resulting in high CO and soot emissions. But this was more related to the small particle size that prevents a sufficient air supply in the pre-gasifier than due to the operation of the flame burner. Tests with the FLOX-burner were carried out using wood chips, rape cake pellets, wheat husks and later on wheat pellets (2 % limestone added). For all tested fuels the combustion in the FLOX-burner was very clean and CO emissions were normally below 30 mg/m3. The burner can be operated down to 3 vol-% excess oxygen without an increase in CO emissions. The operation at lower excess oxygen results in a better efficiency of the system. Table 5 CO and NOx emissions for the tests with and without integrated FLOX-burner
Flame FLOX Flame FLOX Flame FLOX
wood chips ~ 200 < 30 ~ 200 100 - 150 7 3
rape cake pellets n.o. < 30 n.o. 800 - 950 n.o. 3 - 4
wheat husks * 100 - 200 < 30 350 500 - 600 7 3 - 4
wheat pellets(2 % limestone) n.t. < 30 n.t. 600 - 800 n.t. 4
CO in mg/m3 Excess oxygen (lower limit) in vol-%NOx in mg/m3
Fuel
* – slagging problems n.o. – operation not possible n.t. – not tested
lambda
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The tests have shown that the integration of the FLOX-burner brings several advantages compared to the configuration without the burner. Still one objective, the reduction of NOx emissions, is not achieved yet. FLOX-burner can successfully suppress thermal NOx, but for the reduction of fuel-NO further reduction measures has to be applied. The workprogramme within the project was extended and more tests were carried out to analyze the gas quality of the produced gas in the pre-gasifier with special emphasis on N-compounds. Characterisation of LCV gas produced in pre -gasifier
Further tests were carried out with wheat pellets and rape cake pellets to analyse the quality of the gas generated in the pre-gasifier with special focus on N-compounds. These measurements will proof the application of an air-staged burner for the existing test facility. The gas analyses show that the gas quality is slightly increasing with decreasing lambda, but the produced gas in the pre-gasifier is still of poor quality and the gas can still contains considerable amounts of oxygen depending on operation conditions. To enhance the gas quality and thus to reduce the oxygen level in the pre-gasifier an external fuel gas recirculation to the pre-gasifier was installed at the test facility. During the tests with flue gas recirculation an improvement of the gas quality could not be observed and the gas quality is even worse than in the tests without flue gas recirculation. For a better understanding of the NO formation within the burner additional tests were carried out to analyse the amount of NO-precursors and the already formed NO in the produced LCV gas. It was obviously that the amount of NO-precursors is correlated to the amount of NO present in the gas. In gases with a high content of NO the concentration of NH3 and HCN is low. Here, a higher rate of NO-precursors is already converted to NO within the pre-gasifier. The tests have shown the air distribution within the pre-gasifier is very inhomogeneous and thus the conversion of fuel to LCV gases and thus the conversion of fuel-N to NO-precursors are hardly dependent on the local conditions in the pre-gasifier. Furthermore, the tests have shown that with increasing nitrogen content in the fuel the conversion of nitrogen is decreasing. For wheat pellets with a nitrogen content of 2.0 wt-% the conversion to NO is in the range of 12 to 14 mol-%, but with rape cake pellets only 6 to 7 mol-% of the nitrogen is converted to NO. The same observation can be made for the conversion of NO-precursors to NO. For gases with a high concentration of NH3 and HCN the conversion is lower than for gases with lower N-precursor concentration. The presence of high amounts of N-compounds in the LCV gas during combustion promotes the reduction to N2. Thus, the application of an air staged FLOX-burner can combine both NOx reduction technologies to achieve the best NOx reduction level. However, for the existing facility the integration of an air-staged burner is not feasible as the gas is of poor quality and the still contains considerable amounts of oxygen. Thereby, a reduction zone in the first stage of the burner under FLOX-conditions can not be achieved as a high momentum of the air supply can not be obtained due to the low amount of air required. For the application of a staged FLOX-burner a better gas quality, that means a better gasification, has to be achieved, but that is normally given for commercial gasifiers. First investigations at IVD regarding staged FLOX-burners were carried out by CFD simulations. Here first designs of a staged FLOX-burner were investigated. Design of the prototype burners for industrial testings
Prototype of FLOX-burner for FW test site Although the original work plan has not foreseen industrial tests before the third project year tests at FW test site had to be advanced as the test facility was not available for testing in 2005 anymore. Therefore industrial tests with a prototype FLOX-burner were planned for December 2004. For the tests at FW test site WS-Wärmeprozesstechnik designed a prototype
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FLOX burner suitable for syngas combustion in co-operation with FW and USTUTT. The burner design is shown in Figure 22.
Figure 22 FLOX burner for industrial tests at FW site
Prototype of FLOX-burner for ZAMER test site Further industrial tests were planned for project year 3 by IEN. IEN has selected a Polish industrial partner - Mechanical Works ZAMER – for field tests. ZAMER (www.zamer.com.pl) is a small factory specialised in production of medium size water boilers (up to 50 MW) for central heating and employing about 45 people. It is also only Polish manufacturer of commercial gasifiers. For the purpose of BIO-PRO a 500 kW up-draft gasifier located at ZAMER itself has been chosen. The gasifier supplies gas to the water boiler, which is used for heating of the factory. Spear heat is accumulated in the water tank. According to reported process data by IEN WS in co-operation with USTUTT designed a staged FLOX-burner. The staged FLOX burner is shown in Figure 23.
Figure 23 FLOX burner for ZAMER gasifier
FLOX prototype burner for landfill gases WS designed a FLOX-burner for landfill gases in co-operation with FASTE. The burner design is shown in Figure 24. The burner was manufactured by WS and delivered to FATSE end of May 2006. Burner commissioning and testing will be carried out by FASTE and is planned for June 2006.
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Figure 24 FLOX burner for landfill gases
1.3.3.2 Burner development – S-burner (COSTAIR/BioSwirl) Design of COSTAIR burner for BioSwirl gasifier and measurement results
In the first step numerical simulations have been carried out to find the suitable shape of air distributor and the corresponding arrangement of air openings on it. Figure 25 shows the new TPS burner construction based on the optimized COSTAIR burner variant for 30 kW. Numerical Results achieved confirmed that a cylindrical air distributor would lead to high CO emission and long flame, whereas a conical air distributor has lower CO emission and better burn out. In closed collaboration with partner TPS the new design of the COSTAIR burner for the BioSwirl gasifier with conical air distributor was set up and the gas and air supply system was changed. GWI did an extensive program of numerical simulations to find the optimum of air distributor construction.
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Figure 25 COSTAIR burner for BioSwirl gasifier with conical air distributor for 30 kWth GWI built the new COSTAIR burner for 30 kWth shown in Figure 25 and performed experiments on it. NH3 was mixed to the gas mixture to simulate a real composition as from biomass gasification process. N2 was also mixed to the secondary air to find the potential of NOx and CO emission reduction by flue gas recirculation and admixing to the secondary air. Results proved that CO emission does not depend on NH3 component; CO values are mostly single digit. The NOx emission highly depends on NH3 amount in the mixture, as shown in Figure 26Fehler! Verweisquelle konnte nicht gefunden werden.. Concerning the reduction of NOx by recirculation of flue gas and admixing it to secondary air the following conclusions can be made:
A low amount of flue gas admixing to the secondary air does not lead to essential reduction of NOx. Higher amounts seem to provoke a good NOx reduction (for example 30 vol.- % flue gas amount led to about. 25 % NOx reduction)
Flue gas admixing has no any effect on CO emission level
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Figure 26 NNOOxx eemmiissssiioonn vvaalluueess ooff tthhee CCOOSSTTAAIIRR bbuurrnneerr aatt 3300 kkWWtthh Tests with the COSTAIR burner at TPS BioSwirl gasifier
In this work a state-of-the-art burner for biomass fuels was developed where a gasifier from partner TPS was used together with a burner developed from the COSTAIR concept from partner GWI. The COSTAIR concept is developed for increased control of addition of air to the combustible gas. This makes the concept suitable for use in a biomass combustion system for minimisation of NOx-emissions. The gasifier/burner system uses crushed or pulverised fuels and gasifies the fuel in a pre-chamber. The syngas is immediately burnt in the second stage burner that was developed in this work. The principle of the combustion system is shown in Figure 27. This system was installed, commissioned and tested with the original burner in Task 3.1 and 3.2. In the commissioning tests, initial tests with fuel S3 and S5 was performed to see if the combustion system, including fuel feeding, could handle and burn such fuels as they have not been used before. The initial test showed that the fuel S3 – flour mill residue was not suitable for this system and it was decided not to include this fuel in future tests in Task 3.4. Fuel S5 – oil mill residue was on the other hand suitable for this test facility. Fuel S1, S2 and S4 was all wood based fuels and it was known from earlier tests that they were suitable for this test facility.
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Figure 27 System with bioswirl gasifier/burner
Based on bench-scale tests and CFD simulation in WP2, a prototype burner was designed and built for pilot scale tests (2 MW) at TPS as a part of WP3. The design and overall measures of the second stage burner (air distributor) is shown in Figure 28 and the manufactured burner is shown in Figure 29. The design of the (Bio-Pro) burner is completely new and significantly different from the original design with respect to air/gas mixing and flow field. Installation of the Bio-Pro burner at the test facility was performed in Task 3.3.
Figure 28 Design of burner (air distributor) Figure 29 Manufactured burner
Tests with the Bio-Pro burner developed from the COSTAIR concept, was done in Task 3.4. Two test series were performed that are reported in deliverable D 3.4 and D 3.4.b. The results from the tests were evaluated and compared with the project objective regarding emission levels and also evaluated with respect to the potential of the burner as a commercial product. Neither of these two requirements on the burner performance or qualities was fulfilled after the first test series that was reported in D 4.3. At this stage it was decided not to proceed with industrial testing in WP5 but instead continue with further development and testing in the 2 MW test facility at TPS. The results from the second test series is reported in D 3.4.b.
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In the second test series a concept with recirculation of flue gases and mixing with secondary air was used to reduce emissions of NOx. Wood pellet and rapeseed cake (oil mill residue) was used in these tests. In the case with rapeseed cake the effect of flue gas recirculation was significant for oxygen content above 4 – 5 % in the flue gas. This effect was however not so obvious in the other cases with lower oxygen content and/or with wood pellet. But even without flue gas recirculation the emissions of NOx was lower compared to the first test series that is most likely an effect of a more stable flame. This was a results of a more even air distribution thanks to a better configuration of the air inlet to the burner. In Table 6 and Table 7 the obtained emission levels of NOx and CO after the first and second test series is shown. The figures are shown in two columns normalised to 6% and 13% O2 in the flue gas and a third column with project objective emission that are valid at 13% O2. The development work in task 3.4 has lead to a reduction of NOx emissions with about 25% with wood pellet and in average a 50% reduction in NOx emissions with rapeseed cake. Table 6 NOx emissions, first and second test series, wood pellet and rapeseed cake
NOx (mg/Nm3) @ 6% O2 @ 13% O2 Project objective (@ 13% O2) Wood pellet, 1st test series 200 – 250 110 – 130 90 Wood pellet, 2nd test series 150 – 200 80 – 110 90 Rapeseed cake, 1st test series 800 – 1400 430 – 750 750 Rapeseed cake, 2nd test series 400 – 800 210 – 430 750 Table 7 CO emissions, first and second test series, wood pellet and rapeseed cake
CO (mg/Nm3) @ 6% O2 @ 13% O2 Project objective (@ 13% O2) Wood pellet, 1st test series 50 – 70 30 – 40 20 Wood pellet, 2nd test series 50 – 70 30 – 40 20 Rapeseed cake, 1st test series 30 – 40 15 – 20 30 Rapeseed cake, 2nd test series 30 – 40 15 – 20 30 The results show that the developed burner from the COSTAIR concept can perform satisfactorily regarding emission levels and mechanical strength if it operated at the condition similar to the tests performed. From this point of view the burner could be used in a commercial installation. Questions that still remain are how the burner performs at different load regarding air distribution and cooling of the burner wall. The test did also not provide enough information about possible problems of deposits after long-term operation, this is however a problem that most burner can suffer from depending on fuel properties. A final question is also if the relatively complicated design of the air distribution will make the burner too expensive to manufacture. The price for the prototype burner, designed for 2 MW, used in these tests was approximately 3000 €. This price could most likely be reduced if the burner is industrially manufactured in larger numbers. The price is however on the same level as the cost for the original swirled burner and should not be an obstacle for commercialisation.
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1.3.3.3 Burner development –S-burner (advanced NOx-reduction) Advanced NOx-reduction for S-burner design (FLOX)
Gases from solid biomass gasification are voluminous, hot and pressureless. Therefore a FLOX-burner design had to be developed which allows a handling of the fuel gas without blower. Two possibilities can fulfil this demand: using the combustion air as an injector to suck the fuel gas into the combustion chamber or using the air velocity to mix with exhausts first to reduce the O2-partial pressure and heat up. In the second case, the mixing with the fuel gas takes place later at lower gas velocities similar to first generation FLOX burners. While USTUTT tested the first case, FATSE tested the second possibility in the shape of a double staged toroidal-shaped FLOX burner. In first tests, the concept was tested with a NO-injected natural gas burner applying the above mentioned staged toroidal design.
Figure 30 Staged toroidal shaped FLOX burner for hot and pressure-less fuel gas. The red arrows
indicates the flow of the fuel and/or the exhaust, the blue arrows indicate the air injection
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Figure 31 Test results with NO-injection in natural gas.
At the beginning of the test as shown in Figure 31 (13.75) the FLOX burner is operated as a single-stage burner with air excess ratio λ = 1.15. The NOx-emission are indicated to be around 35 mg/m3
n (@ 3% O2). After injection of 350 mg NO per m3 (13.8 and later), the value for the NOx-emission rises accordingly. Reducing the air excess ratio of the first burner to
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substoechiometric values (λ = 0.95) the NOx-emission are not reduced to zero but to 20 to 30 mg/m3
n. After injecting air into the second stage (14.07) to reach again a total air excess ratio of λ = 1.15, the NOx-emissions are measured to be 160 to 170 mg/m3
n. The staging resulted in a NOx-reduction of over 60% of the injected amount. After stopping the injection of NO (14.30), the double-stage burner shows similar NOx-emissions levels as the single-stage burner. After this promising tests a 20 kW gasifier and staged FLOX burner for bio-pellets was designed, produced and installed by FATSE. The wood-pellet burner, in this case operated as a gasifier, is a gift of Ökofen (Austria). Short before the Bio-Pro consortium meeting was held at FATSE facilities in Langenbruck and Klus (project month 30), the first test could be performed on the installation. After measuring a lower reduction effect as expected the insulation of the reduction chamber was improved. This changing did even reduce the reduction effect. As the gases did not have anymore contact with nickel-containing steel after adding the additional inner insulation, Nickel was added into the combustion. This combination resulted in the best reduction effect. However the reduction has been always lower than expected from the preliminary tests with NO-injection. With both fuels wood-pellets and miscanthus-pellets, the reduction effect applying the staged FLOX burner did not exceed 40%. Figure 33 summarizes the findings with wood combustion: The state of art boiler (applying primary and secondary air) has higher NOx emissions with lower total air excess ratio at values between 140 to 180 mg/m3
n (@ 13% O2). This shows clearly the presence of “thermal NOx”, generated from the nitrogen in the combustion air. Applying a FLOX burner without air stageing, the NOx-emission is not only lower (100 to 140 mg/m3
n @ 13% O2) but the dependency of NOx to the air ratio and therefore temperatures is not anymore visible. This is the main effect of flameless oxidation. With the staged FLOX burner, the NOx emissions are again lower (70 to 100 mg/m3
n @ 13% O2) and is now lower with lower air ratio and therefore higher combustion temperature. A reason for this behaviour is the increasing efficiency of the reduction zone with higher temperature.
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Figure 32 Presentation of the staged solid fuel FLOX in service during the meeting of the project consortium (June 20th 2006). The smaller picture shows the three combustion chambers from (gasification, reduction and final combustion).
FATSE/ms,zu: measurements february/may 2006, fuel from same delivery load, FLOX-burner λp = const. = 0.6
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Figure 33 Summary of comparative tests. NOx emissions in relation to total air excess ratio and
technology.
The results did not satisfy completely because the finally received values of 70 to 90 mg/m3
n @ 13% O2 are not lower than the best staged burner concept without FLOX-technology. However it could be shown that FLOX technology has a positive effect on the stability of the process and the CO-emissions:
Messungen Februar/Juni 2006, gleiche Charge Pellets, FLOX-Brenner λprimär = konst. = 0.6
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Figure 34 CO-emission in relation to total air ratio and technology
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In Figure 34 it is clearly visible that the staged FLOX burner can be operated at air excess ratios and CO-emissions similar to state-of-art gas burners. With both emissions the project objectives could be clearly underbid. The project objectives are: < 108 mg/m3
n @ 13% O2 NOx and <30 mg/m3n @ 13% O2 CO.
Due to the high robustness of the design with the air nozzles placed in the “cold” walls of the combustion chamber and the lower NOx emission values achieved, the design was later transferred to be applied in the 120 kW gasifier/burner unit at USTUTT. The premixing of air and exhaust seems to be more important than the fast mixing of fuel and air. However the generally instantaneous and perfect mixing of the FLOX-technology does not result in significantly lower NOx-emissions compared to state-of-art technology, where the slow mixing is producing an effect understandable as multi-staging and therefore supporting multi-site reduction effects without the presence of a clearly defined reduction zone. However FLOX technology showed its robustness and the ability to produce well defined conditions in the combustion chambers. With this advantage, the technology provides a solid basement for further optimisations such as the ember-bed-cooling with exhaust recirculation.
1.3.4 Development of the control system (WP 4) The main aim of the work of TUD as partner in the BioPro project was to contribute to the further research into and development of parts of a control system to be demonstrated for FLOXTM combustion. The aim was to minimize especially the CO emissions down to levels of lower than 30 mg/mn
3. The tasks were subdivided into 4 main areas:
- Development of an on-line fuel gas analyser (OFGA) for gas heating value characterization aimed at application in feed forward control of flameless oxidation burners.
- Setting up guidelines for control strategies of flameless oxidation G-L burners in different boiler control configurations.
- Computational Fluid Dynamics modelling and simulation of a typical flameless oxidation burner (FLOXTM G-L burner delivered by WS Wärmeprozesstechnik)
- Performing combustion experiments on low-medium calorific value gas targeted at minimizing emissions to acceptable levels.
In the following part, a description of the main results and their implication is given per area of research.
1.3.4.1 Development of an on-line fuel gas analyser (OFGA) Within the framework of the project, a design of a new on-line heating value analyser for a wide variety of low calorific value gases has been proposed. The analyser is aimed at forming a part of a feed-forward burner control loop in order to anticipate to the changing heating value of the incoming fuel gas, with the target to maintain the (very) low pollutant emissions of the novel flameless oxidation combustion technology (CO and NOx in particular). Commercially available heating value analysers appeared to be unsuitable for the use in the BIOPRO project, mainly due to their specifications (response time of the order of more than 10 s, inability to cope with CO as gas constituent) and costs. Therefore a new design has been
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proposed, which should overcome the deficiencies of the commercial units, and at the same time yield acceptable accuracy. To verify the proposed design and judge its applicability in the control loop, a prototype of the analyser has been built at TUD. The measurement principle is very closely related to downstream gas processing, so that changes of the gas are kind of mimicked in the device. The advantages of the analyser based on that principle are that the device is simple, cheap and is characterized by a short response time. Series of stability and repeatability experiments have been done with the first prototype of the analyser shown in Figure 35, together with validation experiments for the theory behind the design. It can be concluded, that the proposed device is suitable for the estimation of the heating value of LCV gases as defined in the BioPro project, but it requires further layout refinement in its development.
Figure 35 Picture of the first prototype of the analyzer
1.3.4.2 Guidelines for control strategies of flameless oxidation G-L burners in different boiler control configurations
Combustion of standard fossil fuels and alternative fuels in commercial and industrial boilers results in emissions. Main concerns are carbon monoxide and nitrogen oxides. CO is usually formed when there is a lack of oxygen in the combustion process or when a flame is ‘chilled’. NOx is the collective term for nitrogen oxide gases. The formation of NOx is a complex process which takes place in the pre-combustion, combustion and post-flame regions. Reducing air pollution emissions depends on a number of factors – the fuel used, the local conditions, the design of the combustion chamber, heat release, and the design of the burner. (how well does it complement the design of the boiler). NOx controls can be classified into two types: post combustion methods and combustion control techniques. Post combustion control methods include: Selective Catalytic Reduction and Selective Non-Catalytic Reduction. Combustion control techniques include: Low Excess Air Firing, Low Nitrogen Fuel Oil, Air Fuel staging (rich-quench-lean combustion), Burner Modifications (e.g. using a FLOX combustor), Biased Firing, Water/Steam Injection and Flue Gas Recirculation.
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In today's equipment, high levels of CO emissions primarily result from incomplete combustion due to poor burner design or firing conditions (for example, an improper air-to-fuel ratio) or possibly a leaky furnace. Carbon monoxide is a pollutant that is readily absorbed in the body and can impair the oxygen-carrying capacity of the hemoglobin. Through proper burner maintenance, inspections, operation, or by upgrading equipment or utilizing an oxygen control package, the formation of carbon monoxide can be controlled at an acceptable level. High flame temperatures and intimate air/fuel mixing are essential for low CO emissions. Some NOx control technologies used on industrial and commercial boilers reduce NOx levels by lowering flame temperatures by modifying air/fuel mixing patterns. The lower flame temperature and decreased mixing intensity can result in higher CO levels. The selection of a control strategy to lower all emissions is a balance between fuel cost, safety, boiler load and control system cost. This will eventually determine which of these systems best suits the process involved. However, in practice, the use of parallel positioning systems on boilers up to 650 kW is usually the most economical. Crosslimited systems are typically used in critical load applications of 750 kW and higher. For the BioPro control system a strategy has been proposed that uses three control loops that each will operate with a different timeframe, see Figure 36. The first control loop has a short time frame and adjusts the amount of air towards to burner in order to achieve stable combustion. The control parameters are temperature and carbon monoxide emissions. The second control loop is activated later when the boiler / burner is operated within margins of the first control loop and lowers lambda in order to increase boiler efficiency. The control parameters in this control loop are the oxygen contents of the flue gas and the exhaust temperature of the burner / boiler. The final control loop has even a larger timeframe, this control loop focuses on the emission of nitrogen oxide. This third control loop counter balances the second control loop that can cause higher thermal NOx at lower lambda and avoids too low a lambda. Main control parameters for this loop are the temperature of the preheated air or the flue gas recirculation rate.
Figure 36 Overview of proposed control strategy for burner-boiler combination.
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1.3.4.3 Computational Fluid Dynamics modelling and simulation of a typical flameless oxidation burner (FLOXTM G-L burner delivered by WS Wärmeprozesstechnik)
TUD set up a CFD model of the G-L burner and performed simulations for this flameless oxidation burner type. The grid of the 3D model is shown in Figure 37.
Figure 37 The 3D mesh of the CFD model of the G-L combustor.
The results show that CFD models are capable to describe qualitatively the ´flame´ shape and a typical temperature profile for both natural gas and syngas combustion is shown in Figure 38.
Figure 38 Typical CFD result of the temperature field for syngas (left) and natural gas combustion. In particular an accurate description of the thermodynamic properties of the gas and of the effect of flame stretching is essential to describe operations in conditions close to the flameless combustion regime.
When performing 3-D CFD simulations several difficulties arise in particular in defining the correct boundary conditions for heat flux at the combustor walls.
Moreover, in order to obtain reasonable computational times significant simplifications are needed in the description of turbulence and combustion chemistry. These approximations result in a considerable error in estimating the temperature field inside the burner. Nonetheless, numerical simulations can be used to investigate flame extinction near the burner’s nozzles due to flame stretching that result in a turbulent lifted flame. The flame appears to be stabilized in the boundary layer induced by the recirculation zones by means of entrainment of hot combustion products. In general flame stretching has a great influence on the flame shape and depends on the intensity of turbulence. For this reason the simulations predict a different flame shape in the case of syngas or natural gas combustion.
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It is expected that, once thoroughly validated and combined with experimental measurements, this type of simulations will be an important tool to investigate flame stability in FloxTM burners and explore possible design options. In order to avoid these complications it was decided to perform kinetic simulations of the combustion chemistry. This type of simulations allows a parametric description of several important combustion properties using a great number of elementary reactions for hydrocarbon oxidation. In particular, it is possible to determine the laminar flame speed and laminar flame thickness for a syngas composed of H2, CO and inert gases in various concentrations. It is also possible to investigate flame extinction due to strong spatial gradients of velocity (such as those induced by a strong turbulence) that cause a thinning of the flame front. In this way it is possible to estimate the critical strain rate for syngas and to investigate the effect of composition, temperature and recirculation of hot combustion products on flame extinction. This analysis can be used to improve the CFD models extending the simulations to off-specification fuels for which no data are available in literature. This approach can be used to explain qualitatively the difference between syngas and natural gas combustion. In particular it is found that in the case of syngas combustion the lower release of chemical energy results in reduced turbulence intensity. Due to this phenomenon the regime of combustion can be slightly dependent on the fuel used with consequence on flame stability, flame thickness and on the mechanism of turbulence flame interaction.
1.3.4.4 Combustion experiments on low-medium calorific value gas targeted at minimizing emissions to acceptable levels
Main objective of TUD regarding flameless combustion experiments using the 300 kWth,max GL combustor setup was to establish improved boundary conditions for the combustor modeling and to obtain a better insight into burner control strategies aimed at minimizing CO and NO. Target set for CO was 30 mg/mn
3. The existing GL burner operation on natural gas was extended with a Partial Oxidation (POX) unit. These experiments showed very low CO and NO concentration values using the burner on syngas from the POX unit. CO concentrations well below 30 mg/mn
3 (even below 10 mg/mn3
at 3% O2) were obtained with a hydrogen rich gas. An outlet temperature control strategy was applied acting on the (secondary) air of wall cooling, but in fact there was not much to control in view of these low emission values, especially of CO. For the experiments an Auto Thermal Reformer (ATR) unit was used for the production of Low Calorific Value (LCV) gas. This gas was subsequently burned in the G-L FLOX (FLameless OXidation) combustor manufactured by WS Wärmeprozesstechnik GmbH in Germany, see Figure 39.
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Figure 39 FLOXTM burner set up (left) and single burner (right) at the Energy Technology laboratory of
Delft University of Technology
LCV gas was produced in an Auto Thermal Reformer (ATR) unit in which Dutch natural gas is reformed (with air and steam) over a propriety catalyst to a mixture of methane, CO, CO2, N2 and H2 via catalytic oxidation and the gas-shift reaction. The heat of combustion of the syngas could be varied by the ratio of natural gas to air fed to the ATR. Different LCV gases were studied and the compositions of three of these fuels are summarized in Table 8. The gas type 2 was used as the standard gas. All the water vapour present in the LCV gas is condensed by cooling the syngas to about 30 oC. A picture of the ATR unit that was purchased within the framework of this project is shown by Figure 40 .
Figure 40 Picture of the ATR syngas generator
Table 8 The gas compositions of fuels studied for the combustion tests
Gas Type 1 2 3 H2 31.8 34.9 27.5 CO 6.0 9.5 4.2 CH4 7.8 4.2 11.8 CO2 9.2 7.2 9.3 O2 0.4 0.4 0.4 During an experiment the LCV gas had a steady composition. In Figure 41 the composition of the syngas is plotted over a time of almost two hours.
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Figure 41 Typical composition of main gases in the syngas produced by the ATR unit.
It can be seen that the composition is fairly constant. Furthermore, it can be seen that the oxygen of the reforming air is practically depleted (around 0.4 %-vol has remained). The G-L burner consists of 12 fuel nozzles injecting the fuel just before the main inlet nozzles. It was shown by simulation that the fuel and air are fully mixed at injection. After the inlet nozzles a double wall combustion chamber was present. In the annulus cooling air flowed. At a distance of 150 mm on two sides Suprasil® windows are installed for optical access. The measures of the windows are 100 x 50 mm. The composition of the LCV gas was measured with a Sick Maihak S710 system. Non-Dispersive InfraRed absorption (NDIR) technique was used to analyse the CO, CO2 and CH4 contents. For the H2 analysis thermal conductivity technique is used. The composition of the flue gas was analysed with a Sick Maihak S710 system. The oxygen content was measured using a paramagnetic cell. For CO, NO and CO2 NDIR was used. The flue gas could be sampled in two different locations. Firstly, the gas could be sucked over the pyrometer suction probe. This place was used for the oxygen and NO measurement. Secondly, far downstream in the stack, after the flue gas was mixed with the cooling air and further cooled by a water-cooling mantle. Here the CO concentrations were measured. During the experiments the excess air ratio λ was kept constant at 1.5. Other parameters were varied, their ranges can be found in the table below. Table 9 Main combustor operational characteristics
Parameter Value Unit Power 67 & 100 kW Temperature outlet 950 - 1050 oC LCV calorific value 5.9 - 8.7 MJ/mn
3 The power was calculated with the heat of combustion (in MJ/mn
3) and the normal LCV gas flow. The outlet temperature was measured in the stack directly after the combustion chamber with a type S thermocouple. This temperature was controlled by the amount of cooling air passed along the casing. Finally, the calorific value of the fuel is calculated with the volumetric percentages of the combustibles (H2, CH4 and CO) and their heat of combustion. In Figure 42 the flames of the burner can be seen. This is at 100 kWth, outlet temperature of 1050 oC and gas type 2. The picture was taken with a Olympus Mju 400 digital camera, without flash and a intense-ratio of -1.0. This is opposed to what was observed in the past using natural gas and can be explained as a shift from the well stirred reactor regime to the
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wrinkled thick flame regime, as a result of the (high) hydrogen content that increases flame speed.
Figure 42 View of the combustor during operation on syngas, 100 kWth input and outlet T of 1050 oC
Emissions versus combustor outlet temperature
In Figure 43 the measured NO and CO concentrations are plotted versus the outlet temperature. In these measurements the excess air ratio lambda was 1.5, the power 67 kW and the heat of combustion of the fuel 6.5 MJ/mn
3 (gas type 2).
Figure 43 CO and NO emissions (+ and x, respectively) versus combustor outlet temperature;
LCV = 6.5 MJ/mn3, λ = 1,5, thermal power input=67 kW.
Regarding the experimental results, a clear trend is visible for the normalized NO and CO concentrations. With higher outlet temperatures the NO concentrations are increasing very probably because there is more thermal NO formed. On the other hand, the CO concentrations are decreasing with an increasing outlet temperature. This is because the CO is burning completer and faster with higher temperatures. Emissions versus fuel composition
Several different fuels could be generated in the reformer, as indicated before. The CH4, H2 and CO contents could be varied. Over the operable range of the reformer these gasses were burned using the two different nozzles. In Figure 44 and Figure 45 the CO and NO emissions versus the heat of combustion of the fuel are depicted. The thermal power input of the burner was 67 kW and the excess air ratio 2.0. Emissions are increasing at higher heating values, though even for a medium calorific value gas of appr. 9 MJ/mn
3 CO values are still of the order of 30 ppmv at the normalised
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oxygen concentration of 3% agreed upon in the project. Of consideration for combined heat and power are mostly low calorific value gases in biorefineries of this order of magnitude of heating value or lower.
Figure 44 CO emissions versus heating value of the syngas burned
Figure 45 NO emissions versus heating value of the syngas burned
Temperature control by wall cooling
In the framework of this project also a temperature control strategy was designed. The outlet temperature, which was measured in the stack directly downstream of the combustion chamber with a simple thermocouple, was controlled by adjusting the cooling air flow around the combustion chamber. Figure 46 shows the trends of the outlet combustor temperature following a step change in setpoint and Figure 47 the resulting CO and NO emissions at the outlet of the burner downstream the combustion chamber.
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Figure 46 Temperature setpoint change of 950 to 1050 oC combustor outlet during a temperature control
transition.
Figure 47 Trends of CO and NO following the temperature control step
1.3.4.5 Design and optimisation of an integrated controller for the S-burner IEn’s facility (Figure 48) has been reconstructed in order to be able to perform tests with developed controller for the burner: - purchasing of requested materials, equipment, and control elements for the burner controller - modernization of the existing data acquisition system CRPD (subcontractor METASOFT) - montage of the delivered elements and their tests.
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Figure 48 IEn’s facility after reconstruction
In cooperation with USTUTT there have been worked out the outlines for FLOX model burner design for IEn’s facility. There was stated, that the use of the tube (“small combustion chamber” – Figure 48) made of heat-resisting steel would is needed for obtaining proper recirculation zone and temperatures after burner. IEn’s pulverised coal model burner has been reconstructed by WS and mounted at IEn’s combustion stand. The algorithm of the controller has been developed (Figure 49).
Gasifier Tube – small
combustion chamber
Air forgasifier
Start-up burner
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Figure 49 The algorithm of the controller for the S-burner
Controller proceeding: 1 – Is gas generator ready (manual switch)? 2 – Does exhaust fan run? 3 – Does suction cooling air fan run? 4 – Does air to gasifier fan run? 5 – Does downcast cooling air fan run? 6 – Is temperature in “mini” combustion chamber higher than minimum FLOX operating
temperature? 7 – Is temperature in “mini” combustion chamber higher than minimum ignition
temperature? 8 – Is there permanent fault of start-up burner? 9 – Is there manual interrupt (manual switch)? 10 – Control loop adjusts quantity of air to the burner on the basis of oxygen content in the
flue gas
1.3.4.6 Controller optimization During test runs following subjects were investigated:
• Stability of the flame when work parameters have been changing (because there was not possible the measurement of gasifier products flow, whilst gas composition was analysed by chromatograph – quasi online (every 3 minutes) – the dependences have been determined in terms of quality rather than quantity.
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o Gasifier products temperature has little influence on flame stability – after ignition of the flame, the combustion process is similar when gas temperature is 120 °C or 500 °C;
o During standard operation, LHV (Low Heating Value) of gas is about 5000 kJ/Nm3 – there is not any problems with stability of flame during firing such gas, instability occurs when LHV falls below 3000 kJ/Nm3;
o For present configuration of IEn’s facility there is no possibility to measure gas flow (on the basis of fuel balance can be determined average values); it was found that only large fluctuation of gas flow the instability of flame can occur;
o During standard operation (LHV about 5000 kJ/Nm3) the primary air velocity, both high velocity (140 m/s) and small (50 m/s – smallest air velocity than we are able to obtain – fan limitation) has also small influence on flame stability;
o Temperature in combustion chamber – can influence on flame stability only just after ignition of flame, when the wall of “mini” combustion chamber is cold; after about 3 minutes of firing the wall temperature reaches safe level, where there is no danger of flame instability
Summarising: taking into account the low gas quality, FLOX burner tested at IEn’s facility is surprisingly well stable.
• Changing the primary air flow there influence of excess air number on NOx and CO emissions was determined. On Figure 50 – Figure 52 there are presented the results of tests performed on 27-11-2006.
Figure 50 O2, NO and CO emissions during tests on 27-11-2006
Heating up the gasifier
Refilling of the fuel
Regulation of primary air for burner
– Phase I
Regulation of primary air for burner – Phase II
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Figure 51 Primary air flow during tests on 27-11-2006
Figure 52 Dependence between emissions and excess air number
• Determination of parameters necessary for obtaining the FLOX mode of burner work.
The temperatures field in the “mini” combustion chamber for different primary air flows was analysed. Temperatures in “mini” combustion chamber during tests on 27-11-2006 are presented in Figure 53. When the primary air velocity is relatively low (90 m/s) at temperatures field there are large temperature gradients, whilst maximal temperature is about 1200 °C. With increasing of the air flow, the temperature gradients are decreasing. For maximal air velocities in a range of 120 m/s temperatures at the whole “mini” combustion chamber are similar, whilst maximal temperature falls below 1000 °C. The FLOX mode has been achieved (Figure 54 right).
Heating up the gasifier
Regulation of primary air for burner
– Phase I
Regulation of primary air for burner – Phase II
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Figure 53 Temperatures in “mini” combustion chamber during tests on 27-11-2006
Figure 54 Photos of flame inside “mini” combustion chamber: low (90 m/s) primary air velocity (left) and large (120 m/s) primary air velocity – FLOX mode (right)
1.3.4.7 Set up of industrial controllers The burner controller should be considered as a part of the whole gas production and combustion installation. It has to take into account the gasifier, particular fans states, emergency states, etc. Polish Mechanical Works ZAMER has been chosen to install prototype of combustion controller developed by IEn. On the basis of algorithm developed within Task 4.3, after adaptation to ZAMER’s facility the following control algorithm (Figure 55) was designed. Combustion control box has been constructed and installed at ZAMER (Figure 57 and Figure 58).
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Figure 55 The algorithm of industrial controller for the S-burner
Controller proceeding: 1 – Is gas generator ready (manual switch)? 2 – Does air to gasifier fan run? 3 – Does secondary air to burner fan run? 4 – Does primary air to burner fan run? 5 – Does exhaust fan run? 6 – Is temperature in burner’s “mini” combustion chamber higher than minimum FLOX operating temperature? 7 – Is there fault of start-up burner? 8 – Is there manual interrupt (manual switch)? 9 – Control loop adjusting quantity of primary air to the burner on the basis of oxygen content in the flue gas 10 – Control loop adjusting underpressure in combustion chamber
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Figure 56 ZAMER’s facility – flow-control diagram
WENT1 – air to gasifier fan primary air fan WENT2 – primary air fan WENT3 – secondary air fan WENT4 – exhaust fan
Figure 57 The box with industrial controller for the S-burner
PLC controller
Oxygen PID controller
Boiler underpressure PID controller
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Figure 58 Opened box with industrial controller for the S-burner mounted at ZAMER
1.3.5 Industrial testing of prototype burners (WP 5)
1.3.5.1 Industrial testing of first FLOX-prototype burner at FW test site In WP 5, FW scope included testing of the FLOX burner developed by WS-Wärmeprozesstechnik under realistic conditions, with syngas from an operational gasifier in continuous operation, with the aim to study the burner performance and possible effects on boiler in long-term operation.
The test site
The test site was a 1.5-MW Atmospheric Circulating Fluidized Bed Gasification (ACFBG) test facility located at the FW R&D Centre in Finland. Figure 59 shows a scheme of the test facility. The main components were fuel and sorbent feeding system, circulating fluidized bed gasifier, syngas cooler, hot gas filter and syngas combustion facility. In fall 2004 the gasification pilot plant was prepared for the wood pellet gasification tests that provided the required syngas for burner testing. Wood pellets were chosen as fuel for ease of handling and in order to be able to attribute differences in the burner (and process) performance to the selected operating parameters rather than changes in fuel composition. A flue gas−air heat exchanger was installed to preheat the burner combustion air. WS-Wärmeprozesstechnik designed a prototype FLOX burner suitable for syngas combustion in co-operation with FW and USTUTT. WS manufactured the burner and delivered it to the test facility for the first syngas combustion trials with the FLOX burner concept. Figure 60 and Figure 61 illustrate the appearance of the burner and its assembly at the test facility. The side connection is for syngas, and due to the low heat value it is considerably
PLC controller LPG
burner controllerPressure
transmitters
Beeper
PID controllers
Power supplies
Content 54
larger than in burners designed for gases of high heat value, e.g. natural gas. The top connection is for combustion air, the flow rate of which is of the same order of magnitude as for instance in natural gas combustion at the same power level.
FOSTER WHEELER ATMOSPHERIC CFB GASIFIERKARHULA R&D CENTER
GAS COMBUSTOR
ATMOSPHERICCFB GASIFIER
FUEL FEEDING
AIR PRE-HEATERSCRUBBERWASTE WATERTREATMENT
FLY ASHREMOVAL
GAS COOLER
BOTTOM ASHREMOVAL
HOT FILTER
FLARE
Figure 59 Schematic of the FW ACFBG Test Facility
Figure 60 FLOX Burner before Installation and as Assembled in the Combustion Chamber
FLOX PILOT BURNER (NAT. GAS)
Content 55
Figure 61 Combustion Chamber and Gas Cooler of the Syngas Combustion Facility
Gasifier operation
Gasifier operation in wood pellet gasification tests in December 2004 was stable and virtually trouble-free. The FLOX burner was operated on the generated syngas for 176 hours, without interruptions. During 113 hours of the total duration, oxygen enrichment of the gasification air was in use, resulting in more concentrated syngas with higher heat value than in normal air-blown operation. This provided varying conditions for burner testing. The gasifier was run in air-blown mode and at totally three different levels of oxygen enrichment, i.e. approximately 21, 30, 40 or 50 % of O2 in fluidization air, and the fuel input varied from about 0.86 MW to 1.9 MW. During most of the tests the syngas flow rate was in the range of 0.13 - 0.14 kg/s. The fluidized bed temperature was controlled at about 900 °C in all the tests. Syngas downstream of the hot gas filter was found practically free of dust, and its lower heat value varied (mainly with degree of oxygen enrichment) between 4.5 and 7.8 MJ/kg (wet). The ranges of the main combustible syngas compounds were as follows: CO 16 - 27 vol-%, H2 11 - 17 vol-% and CH4 3.8 - 8.1 vol-% (all dry). In high-temperature fluidized bed gasification, the main nitrogen compounds found in the syngas are ammonia (NH3), hydrogen cyanide (HCN) and molecular nitrogen (N2). The contents of ammonia and hydrogen cyanide in syngas depend on the fuel nitrogen content and the conversion of fuel nitrogen to them in the gasifier. The concentrations of NH3 and HCN were measured intermittently by wet chemical sampling, and the ranges were approximately as follows: NH3 300 - 500 mg/m3n (dry) and HCN 30 - 90 mg/m3n (dry). In syngas combustion, ammonia and hydrogen cyanide may convert to nitrogen oxides (NOx) or, ideally, be decomposed to nitrogen.
COMBUSTION CHAMBER
AIR LINES
BOILER
Content 56
Table 10 summarizes the operating parameters of the gasifier and properties of the syngas. The presented values are based on the collected process data and calculated mass balances. Table 10 Gasifier Operating Conditions and Syngas Properties
Burner testing and performance
The FLOX burner was provided with a natural gas operated pilot burner, but it was used only for start-up. For safety reasons, the pilot burner was programmed to go on and off automatically based on the measured combustion chamber temperature. Both functions were tested and found to work as designed, but the automatic ignition was not needed in practice due to stable operation. Air flow to the pilot burner was maintained for cooling purpose and to maintain the readiness for automatic ignition. Besides the primary air flow and pilot burner air flow, there was no other air feeding to the syngas combustion facility. Table 11 and Table 12 summarize the burner operating parameters and properties of the flue gas resulting from syngas combustion. Different burner loads and other operating parameters were tested during steady-state gasifier set points. The fuel input ranged from about 150 kW to 350 kW (LHV), and the air preheater provided an additional 50 - 100 kW of heat input as hot air. The air preheater installed for this project was used all the time, and the combustion air temperature was normally 370 - 430 °C. As the burner was rated at 400 kW and the gasifier nearly fourfold, part of the syngas (typically 20 - 40 %) was led to the burner and the rest was flared. The syngas temperature just before the burner was 160 - 210 °C and inside the burner 220 - 260 °C due to the hotter air and heat from the combustion chamber. Temperature inside the combustion chamber was mostly 950 - 1000 ºC and in few tests from 1100 to 1200 °C, the maximum allowed. To control the temperature, the excess air level was high, with typical flue gas oxygen content of 10 to 13 %. It was not possible to study the effects of low excess air (i.e. less oxygen available for oxidation of NH3 and HCN) or staged combustion. The tested burner operating parameters (air coefficient, temperature, fuel input) had little effect on flue gas NOx emission, but the emission appeared to correlate fairly well with the syngas NH3 + HCN contents, as shown in Figure 62. The NOx concentration ranged from about 220 to 370 mg/m3n (dry, 6 % O2), which corresponds to 70 - 90 % conversion of NH3 + HCN and can be considered normal rather than low. Apparently the objective to create high internal recirculation by a high-velocity air jet (in the middle) and thus prevent hot spots and
Test identification BP1 BP2 BP3 BP4 BP5 BP6 BP7 BP8 BP9Operating parameters:
Fuel input MW (LHV) 1.4 1.2 1.3 1.1 0.86 0.86 1.1 1.3 1.9Gasifying agent - Air/O2 Air/O2 Air/O2 Air/O2 Air Air Air/O2 Air/O2 Air/O2
Bed temperature °C 896 905 897 900 899 887 889 901 893Syngas flow rate g/s, wet 137 127 136 132 134 134 134 134 170
Syngas properties:CO2 vol-%, dry 18.9 18.6 19.0 16.6 14.5 14.6 16.6 19.4 20.8CO vol-%, dry 24.6 23.9 24.0 20.9 16.6 16.4 20.4 24.4 26.9H2 vol-%, dry 17.3 17.1 16.5 13.5 10.9 12.1 16.5 16.5 16.5CH4 vol-%, dry 6.9 6.2 6.8 5.6 4.1 3.8 5.0 6.5 8.1CxHy (incl. tars) vol-%, dry 3.0 2.3 3.0 2.7 1.5 1.3 2.1 2.9 3.3H2O vol-%, wet 14.0 14.0 14.5 13.0 11.0 10.5 12.0 14.5 17.0NH3 mg/m3n, dry -- 401 490 339 298 -- -- -- --HCN mg/m3n, dry -- 34 87 38 33 -- -- -- --Molar weight g/mol (wet) 25.0 25.0 25.2 25.7 26.2 26.0 25.2 25.3 24.9Lower heat value MJ/kg (wet) 7.65 6.97 7.45 6.25 4.54 4.49 6.24 7.29 7.83
Content 57
generation of mainly thermal NOx worked, but the syngas contained enough reduced nitrogen species to generate the measured NOx emissions through oxidation. Reducing the NOx formation from syngas nitrogen species would obviously require additional measures, e.g. staging in the burner and/or furnace. The flue gas CO level was negligible throughout the testing, indicating effective burnout of the syngas. Table 11 FLOX Burner Operating Parameters and Fluegas Properties (1/2)
Table 12 FLOX Burner Operating Parameters and Fluegas Properties (2/2)
Test identification BP1_1 BP2_1 BP2_2 BP3_1 BP3_2 BP4_1 BP4_2 BP5_1 BP5_2Burner operating parameters:
Fuel input kW (LHV) 156 252 350 257 252 182 281 192 302Primary air flow rate g/s 64.1 197 220 196 196 119 217 123 217Primary air temperature °C 427 374 406 385 378 407 373 413 384Primary air pressure mbar, g 16 162 205 160 159 63 192 67 195Pilot air flow rate g/s 26.5 21.2 20.0 19.2 19.1 19.7 19.4 20.7 20.6Syngas temperature °C 159 186 200 193 194 183 209 203 225Syngas flow rate g/s, wet 19.8 35.1 48.5 33.4 32.8 28.1 43.2 40.1 63.2Air coefficient (total) - 2.0 3.0 2.4 2.9 2.9 2.7 2.9 2.7 2.8Combustion chamber t. °C 980 951 1040(1 973 958 955 956 958 970
Flue gas properties:O2 vol-%, dry 9.6 13.1 11.2 12.8 13.0 11.8 12.6 11.1 11.5CO2 vol-%, dry 12.0 8.4 10.4 8.6 8.4 9.2 8.4 9.4 9.0N2 vol-%, dry 78.4 78.5 78.4 78.6 78.6 78.9 78.9 79.5 79.5H2O vol-%, wet 10.8 8.2 9.7 8.3 8.2 8.6 8.0 8.5 8.3CO, at 6 % O2 mg/m3n, dry 3 1 3 6 6 4 5 8 11NOx ppm, dry 105 59 74 98 77 72 71 72 81
at 6 % O2 mg/m3n, dry 284 229 230 370 296 240 261 224 263Molar weight g/mol, wet 29.1 29.0 29.1 29.0 29.0 29.0 29.0 29.0 29.0Flow rate g/s, wet 110 254 288 249 248 167 280 184 301
Convers. NH3, HCN to NOx % -- -- 71 84 86 -- 90 77 81Notes: 1) Temperature not stabilized but rising
Test identification BP6_1 BP6_2 BP7_1 BP7_2 BP8_1 BP8_2 BP9_1 BP9_2Burner operating parameters:
Fuel input kW (LHV) 223 215 199 209 179 182 200 222Primary air flow rate g/s 126 130 141 133 133 127 166 170Primary air temperature °C 430 419 395 414 393 401 395 430Primary air pressure mbar, g 71 75 86 77 75 69 117 127Pilot air flow rate g/s 20.7 20.8 20.9 20.7 20.4 20.4 19.4 19.6Syngas temperature °C 209 209 192 194 178 177 188 203Syngas flow rate g/s, wet 46.9 45.3 30.7 32.2 23.8 24.2 24.8 27.5Air coefficient (total) - 2.4 2.5 2.9 2.6 3.0 2.8 3.2 2.9Combustion chamber t. °C 993 974 943 976 935 951 970 1042
Flue gas properties:O2 vol-%, dry 10.1 10.6 12.4 11.6 13.0 12.5 13.7 13.1CO2 vol-%, dry 10.4 9.9 8.6 9.5 8.6 9.0 8.0 8.6N2 vol-%, dry 79.5 79.5 79.0 79.0 78.4 78.4 78.3 78.3H2O vol-%, wet 9.3 8.9 8.3 9.0 8.1 8.5 8.0 8.5CO, at 6 % O2 mg/m3n, dry 6 5 5 5 6 6 6 6NOx ppm, dry 125 89 76 74 64 69 70 80
at 6 % O2 mg/m3n, dry 351 263 274 242 248 252 295 311Molar weight g/mol (wet) 29.1 29.0 29.0 29.0 29.0 29.0 29.0 29.0Flow rate g/s, wet 194 196 193 186 177 171 210 217
Convers. NH3, HCN to NOx % -- -- -- -- -- -- -- --
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0
50
100
150
200
250
300
350
400
0 100 200 300 400 500 600 700
NH3 + HCN content of syngas, mg/m3n (d)
Flue
gas
NO
x at
6%
O2,
mg/
m3 n
(d)
0
50
100
150
200
250
300
350
400
Flue
gas
NO
x, m
g/M
J
FLOX burner, mg/m3n FLOX burner, mg/MJ
Figure 62 Flue Gas NOx Emission vs. Syngas NH3 + HCN Contents
The burner was found to be in good shape in the post-test inspection. The syngas inlet section of the burner had a thin tarry layer on the wall, as shown in Figure 63 (left). The vertical pipe in the middle is the combustion air pipe, which had remained clean, apparently due to the high temperature of the air and heat from the combustion chamber. The burner itself was virtually intact and clean, as shown in Figure 63 (right). Some scaling and bending of the burner plate had taken place because of missing heat insulation.
Figure 63 FLOX and Pilot Burner after the Test Runs
Summarizing the experiences of the first FLOX burner tests using product gas from a 1.5 MW biomass gasifier as fuel, the burner operation was fully reliable throughout the 176-hour test period. Carbon monoxide emissions were negligible, but the NOx emissions were at the same level as with the old burner of the facility. This has been attributed to NOx formation from reduced nitrogen species in the syngas (mainly NH3, HCN), suppression of which would require further measures. Other partners have studied the issue later on in the project.
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1.3.5.2 Industrial testing of second FLOX-prototype burner at ZAMER test site Modification of the plants for the burner integration
For tests of industrial combustion controller the facility at Polish Mechanical Works has been chosen (Figure 64). ZAMER (www.zamer.com.pl) is a small factory specialised in production of medium size water boilers (up to 50 MW) for central heating and employing about 45 people. It is also only Polish manufacturer of commercial gasifiers. The reference list is not long but all listed gasifiers are in operation in industrial conditions. For the purpose of BIO-PRO a 500 kW up-draft gasifier located at ZAMER itself has been chosen. Such chose enabled easier modification of the system and did not disturb any technological process what could be a problem in other cases. The gasifier supplies gas to the water boiler, which is used for heating of the factory. Spear heat is accumulated in the water tank. In order to determine assumptions for manufacturing of the prototype industrial burner (Task 5.1), it was necessary to find following parameters of gasifier:
• Quantity of gasifier products • Composition and Low Heating Value (LHV) of obtained gas • Temperature of gas
To determine these parameters, two series of test runs were performed for deferent fuels and conditions of gasifier work.
Figure 64 Facility at Mechanical Works ZAMER
In order adjust Zamer’s facility to new burner and developed by IEn combustion control system, Zamer’s staff has carried out the modifications at facility designed under IEn’s supervision. Following modifications were realized:
• The geometry of gasifier products duct has been changed; • To gas duct the container for liquid tars has been added; • Two fans (for primary and secondary air) have been mounted;
Boiler
Origin Zamer’s burner
Gasifier
Content 60
• Four inverters for regulation following fans: - Gasifier downcast fan, - Suction boiler fan, - Primary air to burner fan, - Secondary air to burner fan;
• The burner control box has been constructed and mounted; • Stub pipes for gas analysers and pressure/temperature measurement have been added; • Installation for propane to auxiliary (start-up) burner has been designed and built; • Set of ten propane cylinders has been hired; • For measurement of temperature inside “mini” combustion chamber the set of
thermocouples has been mounted at BIO-PRO burner; • The BIO-PRO burner has been mounted.
Monitoring of the burner operation and performance assessment
After applying the modification at burner design (as result of problems during commissioning of the burner within Task 5.3), there were performed further investigations at Zamer’s facility within Task 5.4 – Monitoring of the burner operation and performance assessment.
Figure 65 Zamer’s facility during test runs within Task 5.4
From performed measurement and on the basis of experience gathered during burner operation at Zamer’s facility following conclusion can be drawn:
1. It is very important that burner for LCV (Low Calorific Value) gas has to have effective flame ignition and maintenance system used during start-up and in case of decreasing of gas quality and/or quantity.
Biomass
Burner
Primary air fan
Secondary air fan
Combustion control box
Facility control box
Gasifier
Analysing and logging equipment: - DaqBook+DasyLab software - set of gas analysers (including chromatograph)
Krzysztof Remiszewski – IEn’s researcher
Boiler
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2. Total amount of air (primary and secondary) to burner has to be regulated to obtain desired level of oxygen in flue gas.
3. Air to burner distribution between primary and secondary should be adjusted in dependence of quality/quantity of gasifier products:
• For low quality/quantity gas mainly primary air should be used in order to provide sufficient amount of oxygen for stable combustion;
• During normal operation (higher gas quality and quantity) air should be divided between primary and secondary duct; amount of primary air has to provide sufficient oxygen level for stable combustion near gas nozzles zone, but without excessive temperature (to minimize of thermal NOx production), whilst suitable amount of secondary air ensures complete combustion of gas.
1.3.5.3 Additional industrial test of FLOX-prototype flare for landfill gases After publishing the results from the LCV-tests with an adiabatic burner at FATSE (reported PM 24 and earlier), market demands supported the decision to step forward and produce a field test unit for lean (weak) landfill-gas. A new industrial consortium has been built up under the leadership of FATSE and WS. As a very positive result of the project BIO-PRO, the company e-flox GmbH was founded in 2006. The company’s main activity is the implementation of FLOX-technology into Bio-Energy applications. In summer 2006, WS therefore delivered the adopted burner not in the shape of a laboratory unit but as a field test unit according FATSE design. The Swiss company TDU GmbH found an appropriate land-fill site in the Ticino (Switzerland) (Figure 66, Figure 67). The FLOX-flare is now in continuous service since November 8th 2006 (begin of PM 36). The control unit is developed by FATSE as well. The unit combusts 50 m3n landfill gas per hour, containing 9 to 11% CH4. Due to presence of a exhaust recuperator and a very good insulation, the unit has to be cooled by increasing the air ratio from 1.2 to 2.0 by adding unheated secondary air. The operation temperature is at present 1150 °C. According this experience, the unit is estimated to be capable to burn land-fill gas down to 6.0% CH4 without changing the design. In it’s present situation, the FLOX Flare combusts 30% more methane as the conventional Flare was capable when the gas quality was better (23% CH4 and higher). The prevented green house emissions are calculated with the information of a gas flow meter and a gas analysis and count up to 700 tons CO2-equivalent per year. The costs of the flare which exceed the budget of Bio-Pro are covered by FATSE and will hopefully financed back partially by a small CO2-emission trade contract with MyClimate. The word “hopefully” refers to the fact that the installation is a test unit without properly predictable life time. However half of the emission trade contract revenues are dedicated for the maintenance of the unit.
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Figure 66 Overview over total flaring installation in Ponte Tresa, Switzerland. 1) security valve on landfill gas line, 2) insulated FLOX-combustion chamber with to temperature measurements (each double redundant) and to monitors, 3) recuperator, 4) control unit, 5) fan for start-burner and FLOX burner, 6) propane for start-up, 7) tubing for control lines, power for ignitor, primary and secondary air and start-up gas, 8) housing for ignitor, manual air pre-settings and start-up burner.
Figure 67 FLOX-flare during endurance testing (foreground, in cage), landfill gas supply and old flares in the background.
Content 63
Results and outlook for gaseous fuels
From landfill site to Bio-refineries: The technology of the LCV-FLOX-Flare and FLOX-burner will be applied mainly in units for the methanisation of Biogas to be fed into the gas-grid. Due to the existence of LCV-FLOX-burners, the Swiss ministery of energy and the foundation “Klimarappen” decided in fall 2006 (PM 34) to account only installations with FLOX-burners to be climate-friendly through their methane-emission-freeness. The measured NOx emissions of the field test unit are 5 to 20 mg/m3
n @ 3% O2. The CO-emissions can be held between 0 to 20 mg/m3
n @ 3% O2, but through the need of secondary cooling air, the combustion process is slowed down after passing half of the residence time in the combustion chamber. Therefore, CO emissions can vary up to 100 mg/m3
n @ 3% O2. For further products, these problems are already solved. Therefore it can be stated, that the adopted burner overbids clearly the project targets of 50% NOx emission reduction compared to state of art (would be 40 mg/m3
n @ 3% O2) and reduction of CO-emission below 20 mg/m3
n @ 3% O2.
1.3.6 Socio-Economic evaluation and dissemination, technical exploitation (WP 6)
1.3.6.1 Life Cycle Assessment of the two developed prototypes In order to investigate the commercial viability of the burners it is necessary to do a life cycle assessment of the two burners and of their application. UU selected three typical applications for this evaluation, based on the results of the market study. UU calculated the operation costs with the new burners. Three typical applications are selected for the assessment and operation cost of the two developed burners: 1) the application of GL-burner to a gas turbine power plant; 2) the application of S-burner to a 1 MW Circulating Fluidized Bed Combustion (CFBC) heat only boiler; and 3) the application of S-burner to a 12 MWe CFBC power plant. To provide a consistent basis for evaluation and comparison, the systems analysed are modelled using the ECLIPSE process simulation package [1 - 3]. ECLIPSE was developed for the European Commission and has been used by the Northern Ireland Centre for Energy Research and Technology at the University of Ulster since 1986 [4, 5]. ECLIPSE is a personal-computer-based package containing all of the program modules necessary to complete rapid and reliable step-by-step technical, environmental and economic evaluations of chemical and allied processes. ECLIPSE uses generic chemical engineering equations and formulae and includes a high-accuracy steam-water thermodynamics package for steam cycle analysis. It has its own chemical industry capital costing program covering over 100 equipment types. The chemical compound properties database and the plant cost database can both be modified to allow new or conceptual processes to be evaluated. A techno-economic assessment study is carried out in stages; initially a process flow diagram is prepared, technical design data can then be added and a mass and energy balance completed. Consequently, the system’s environmental impact is assessed, capital and operating costs are estimated and an economic analysis performed.
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Whilst every effort is made to validate the capital cost estimation data, using published information and actual quotations from equipment vendors, the absolute accuracy of this type of capital cost estimation procedure has been estimated at about 25–30%. However, as the comparative capital cost estimates are based on the accurate calculation by the mass and energy balance program of differences in basic design, families of similar technologies composed of similar types of equipment can be compared on a consistent basis. The following are the detailed results and analyses for the evaluation of the three typical applications. GL-burner – Techno-economic Analysis of Gas Turbine
The ECLIPSE suite of process simulation software was used to simulate a gas turbine, fuelled by natural gas and with a range of burners i.e. 1) a standard conventional burner; 2) a conventional burner with selective catalytic reduction of NOx emissions (SCR); 3) a flameless oxidation (FLOX) burner; and 4) a staged combustion (COSTAIR) burner. In Table 13 the technical results of the 4 systems are summarised.
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Table 13 Technical and Emission results
Gas turbine (Base case)
Gas turbine +SCR
Gas turbine + COSTAIR
Gas turbine + FLOX
Fuel flow (kg/s) 13.17 13.17 13.17 13.17
Inlet mass flow (kg/s) 602.7 602.7 602.7 602.7Turbine inlet conditions ( Pressure Bar ) 15.86 15.86 15.86 15.86
(Temperature ºC ) 1288 1288 1288 1288Turbine outlet conditions ( Pressure Bar ) 1.05 1.05 1.05 1.05
(Temperature ºC ) 566 566 547 519Compressor polytropic Efficiency (%) 90.0 90.0 90.0 90.0Turbine Polytropic Efficiency (%) 87.0 87.0 87.0 87.0
HHV (MJ/kg) 55.12 55.12 55.12 55.12
LHV (MJ/kg) 49.80 49.80 49.80 49.80Thermal input (MW) (HHV) 726 726 726 726
(LHV) 656 656 656 656Gas turbine power output (MWe) 434 434 426 413Total power output (MWe) 221 221 219 215NOx emissions (mg /m3) (5% O2) 112 11.2 22 8.6
Auxiliary (MWe) 3 Transformer losses (MWe) 1 1 1 1Net electricity production (MWe) 220 217 218 214Overall efficiency (%) (HHV) 30.3 29.9 30.0 29.5Overall efficiency (%) (LHV) 33.5 33.1 33.2 32.7
Economic assessment is carried out by ECLIPSE. The results are shown in the Table 14 and the sensitivity analyses in Table 15 and Table 16.
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Table 14 Economic results
Capital cost (in € Million)
Gas turbine (Base case)
Gas turbine +SCR
Gas turbine + COSTAIR
Gas turbine + FLOX
Building 4.5 4.5 4.5 4.5 Extra cost for the new combustor (burner) 0 0 0.3 0.3 Gas turbine with standard combustor 171 171 171 171 Selective Catalytic Reduction 0 13.5 0 0 Total capital cost (TCC) in Million € 175.5 189 175.8 175.8 Specific investment (€/kWe) 799 871 807 820
Table 15 shows the comparison of sensitivity of break-even electricity selling price (BESP) of four NOx reduction systems. Table 15 A comparison of sensitivity of BESP of four NOx reduction systems
Techno-logy used
NOx emissions (mg /m3) (5% O2)
NOx decrease
(%)
BESP (c/kWe) (fuel cost
2.58 €/GJ)
BESP Increase
(%)
BESP (c/kWe) (fuel cost
3.00 €/GJ)
BESP Increase
(%)
BESP (c/kWe) (fuel cost
4.50 €/GJ)
BESP Increase
(%)
Gas turbine
only 112 – 4.25 – 4.65 – 6.05 –
SCR 11.2 90 4.52 6.4 4.92 5.8 6.35 5.0
COSTAIR 22 80.4 4.28 0.7 4.68 0.6 6.11 1.0
FLOX 8.6 92.3 4.35 2.5 4.76 2.3 6.21 2.7 Table 16 shows the comparison of sensitivity of specific investment (SI) of four NOx reduction systems.
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Table 16 Comparison of sensitivity of Specific Investment (SI) of NOx reduction systems
Technology used
NOx emissions (mg /m3) (5% O2)
NOx decrease (%) SI ( €/kWe) SI Increase (%)
Gas turbine only 112 – 799 –
SCR 11.2 90 871 8.8
COSTAIR 22 80.4 807 0.9
FLOX 8.6 92.3 820 2.6 The above assessment of alternative NOx reduction technologies to the conventional simple gas turbine cycle was successfully completed using the ECLIPSE process simulator. Compared to the conventional simple cycle gas turbine power generation, the NOx emissions for SCR reduced 90%; for COSTAIR reduced 80.4%; for FLOX reduced 92.3%. With a natural gas price of €2.58/GJ ( €90 /per1000m3), €3.00/GJ (€105/per1000m3) and €3.50/GJ (€157/per1000m3), the BESP for the simple gas turbine cycle were 4.24, 4.64, 6.05 c/kWh and SI was 800 €/kWe; compared to this basic case, the BESP for SCR were 4.52, 4.92, 6.35 c/kWh, the SI was 870 €/kWe, an increase of 8.8%; the BESP for COSTAIR were 4.29, 4.69 and 6.11 c/kWh. The SI was 807 €/kWe, an increase of 0.9%; the BESP for FLOX were 4.35, 4.77 and 6.22 c/kWh. The SI was 820 €/kWe, an increase of 2.6%. The sensitivity analyses showed that SCR system had the highest BESP and SI; FLOX had the medium, COSTAIR had the lowest. The results from techno-economic analysis showed that the COSTAIR and FLOX had the technical and economic advantages over SCR. This makes it possible to apply them to the gas turbine system in the near future. S-burner – Techno-economic Analysis of 1 MW CFBC Heat Only Boiler
The solid biomass fuels used in the investigation are from the “Market Study Fuels”; the report of “Report with analysis data” and the first year activity report. The following table (Table 17) shows the main data for the fuels studied.
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Table 17 Characteristics of the studied fuels
Fuel Moisture[%]Ash [%]
Combustible particles[%]
Heat value [kJ/kg]
S1 Wood chips (deciduous) 12.38 3.24 84.38 18827
S2 Pellets (Sweden) 8.09 0.31 91.6 18847
S3 Wheat bran (Szymanów
mill) 12.13 4.74 83.13 16830
S4 Sawdust (dedicuous) 18.73 0.33 80.94 19046
S5 Separator oil cakes 4.65 6.24 89.11 20874
Straw 12.1 3.2 84.7 19100 Wood-REF 25.0 4.4 70.6 20500
ECLIPSE was used to simulate the 1 MW heat only boiler, fuelled by biofuels listed Table 17, with a range of burners i.e. 1) a standard conventional Circulating Fluidized Bed Combustion (CFBC) burner; 2) a conventional Circulating Fluidized Bed Gasifier (CFBG) with a normal burner; 3) a CFBG with a flameless oxidation (FLOX) burner; and 4) a CFBG with a staged combustion (COSTAIR) burner. Table 18 shows the results of the fuel consumed for the heat plants from the simulation using ECLIPSE. The results show that the fuel consumptions are from 6.61 to 8.27 tonnes/day of the raw biomass for the 1 MW heat only boiler; the average is 7.26 Tonnes/day. Table 18 Fuels consumed for the heat boiler/plant
1 MW heat only boiler/plant
Fuel Flow
(daf, Tonnes/day) Fuel Flow (raw,
Tonnes/day)
S1 6.06 7.18
S2 6.05 6.61
S3 6.87 8.27
S4 6.19 7.65
S5 5.28 5.92
Straw 5.96 7.03
Wood-REF 5.74 8.13 In Table 19 the technical results of the 4 systems are summarized, with the reference fuel (S1 – dry wood chips). The fuel consumption for all of the four systems is 6.06 Tonnes/day (daf – dry and ash free). For the first case, the conventional CFBC, the thermal output (heat generated) is 1.121 MW,
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the thermal efficiency is 91.14% for the Low Heat Value (LHV). The emissions of NOx are 212 mg/Nm3 and the CO emission is 51 mg/Nm3. The additional power consumptions are 31.3 kW for the operation of the system. For the second case, the conventional CFBG with a normal burner, the thermal output (heat generated) is 1.121 MW, the thermal efficiency is 91.14%. The emissions of NOx are 210 mg/Nm3 and the CO emission is 50 mg/Nm3. The additional power consumptions are 31.7 kW for the operation of the system. For the third case, the CFBG with a FLOX burner, the thermal output (heat generated) is 1.12 MW, the thermal efficiency is 90.81%. The emissions of NOx are 21 mg/Nm3 and the CO emission is 30 mg/Nm3. The additional power consumptions are 37.7 kW for the operation of the boiler. For the fourth case, the CFBG with a COSTAIR burner, the thermal output (heat generated) is 1.12 MW, the thermal efficiency is 90.73%. The emissions of NOx are 31 mg/Nm3 and the CO emission is 30 mg/Nm3. The additional power consumptions are 37.7 kW for the operation of the boiler. From the results, it can be seen that the thermal efficiencies of the conventional CFBC and the conventional CFBG with a normal burner are high, but the NOx and CO emissions are also high. The thermal efficiency of CFBG with a FLOX burner is a little lower, the difference is 0.36% comparing to the former two cases; but the NOx emissions are much lower, 90% less than those of the former two cases. The thermal efficiency of the CFBG with a COSTAIR burner is also lower, the difference is 0.45% comparing to the former two cases; but the NOx emissions are 82% lower than those of the former two cases. The CO emissions from the first two cases are high. They are 51 mg/Nm3 for normal CFBC system and 50 mg/Nm3 for the CFBG with a normal burner. The CO emissions from FLOX and COSTAIR are from 40.9% to 38.4% lower than that of the former two cases.
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Table 19 Technical Results for 1 MWth Biofuel “Heat Only” System (fuel S1)
Combustion
Gasification + normal
Combustion Gasification
+FLOX Gasification + COSTAIR
FD-Fan 13.1 13.3 18.8 18.8
ID-Fan 2.2 2.2 2.9 2.9
Ash Box 1.3 1.3 1.3 1.3
Gas Cleaning 0.1 0.1 0.1 0.1
Ash Convey 1.3 1.1 1.1 1.1
Fuel -Convey 12.7 12.7 12.7 12.7
HP Pump 0.4 0.7 0.5 0.5
Hot water pump 0.2 0.2 0.2 0.2
Total (kW) 31.3 31.7 37.7 37.7
Heat generated (MW) 1.121 1.121 1.117 1.116
Biofuel Type S1 S1 S1 S1
Fuel Flow (daf) Tonnes/day 6.06 6.06 6.06 6.06
Steam Cycle (bar / ºC) 4.85/151 4.85/151 4.85/151 4.85/151
Thermal Input LHV (kW) 1.23 1.23 1.23 1.23
Thermal Input HHV (kW) 1.31 1.31 1.31 1.31
Efficiency LHV (%) 91.14 91.14 90.81 90.73
Efficiency HHV (%) 85.70 85.70 85.40 85.32
Exhaust Gas Temp (ºC) 121 113 113 113
CO2 g/kWh 398274 398029 403577 403026
SO2 mg/Nm3 0 0 0 0
CO mg/Nm3 51 50 30 30
NOx mg/Nm3 212 210 105 126
O2 (dry) Volume % 5.43 5.10 9.14 8.95 Economic assessment is carried out by ECLIPSE. Additional costs due to incorporating the FLOX or the COSTAIR burners in each system were considered, but in fact it was found that no significant overall increase in costs would be necessary for the manufacture, installation or operation of such burners. The results for the 1 MWth heat only boilers and the sensitivity analyses are shown in Table 20.
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The results show that the total capital investment is 1188 k€ and the specific investment 1060 €/kW for the case of conventional CFBC; the total capital investment is 1322 k€ and the specific investment 1169 €/kW for the case of CFBG with a normal burner; the total capital investment is 1433 k€ and the specific investment 1284 €/kW for the case of CFBG with a FLOX burner; and the total capital investment is 1388 k€ and the specific investment 1244 €/kW for the case of CFBG with a COSTAIR burner.
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Table 20 Economic Results for 1 MWth Biofuel “Heat Only” System
CFB
Combustion
CFB Gasification
+ normal burner
CFB Gasification
+FLOX
CFB Gasification +COSTAIR
Euros Euros Euros Euros Plant type Heat only Heat only Heat only Heat only Output 1 MWth 1 MWth 1 MWth 1 MWth Fuel Reception & Storage 72389 72389 72389 72389Limestone and sand R&S & dosing 3665 3665 3665 3665Fuel Milling & Storage 4582 4582 4582 4582Fuel Feeding 53146 53146 53146 53146
Sub Total 133782 133782 133782 133782Ash/Slag Handling 10538 10538 10538 10538BFBC (inc. fans, pumps, buildings, elect. equipment) 856194 0 0 0Gasifier+burner 0 973000 973000 973000BFBC HRSG + Accumulator 24282 24282 24282 24282
Sub Total 891014 1007820 1007820 1007820Additional cost for FLOX burner 0 0 97300 0Additional cost for COSTAIR burner 0 0 0 58380Selective Catalytic NOx Reduction System 0 0 0 0Condenser, Cooling Water 5498 5498 5498 5498Water Treatment 4856 4856 4856 4856Chimney 3207 3207 3207 3207
Sub Total 13561 13561 110861 71941Total cost (in €) 1038357 1155163 1252463 1213543Total cost (in k €) 1038 1155 1252 1214
Capital fees (%) 2 2 2 2Contingence allowance
(%) 10 10 10 10Working capital (%) 2 2 2 2
The total capital investment (in k €) 1188 1322 1433 1388Specific investment
(€ / kW heat) 1060 1169 1284 1244 The cost for the CFBG with FLOX is the highest, but it has the best effect to reduce NOx and CO emissions, as seen in Table 20. The cost for CFBG with COSTAIR comes the second and it has also good effect on NOx and CO reductions. The cost of CFBG with normal burner is
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the third one and has no NOx and CO emission reduction effect. The cost of conventional CFBC is the lowest, but it emits high NOx and CO. The above assessment of alternative NOx reduction technologies to the conventional CFBC and CFBG with normal burner was successfully completed using the ECLIPSE process simulator. Compared to the conventional CFBC heat generation, the NOx emissions for CFBG with normal burner reduced 0%; for CFBG plus COSTAIR reduced 80%; for CFBG plus FLOX The NOx-reduction depends largely on the fuel. You may use 90% reduction for thermal NOx and 50% reduction for fuel NO. Because many biofuels contain fuel bound nitrogen an overall reduction of 50% was used for simplification. With a wood chip price of 0, 20 and 40 €/tonne, the BESP for the conventional CFBC were 21.91, 26.34 and 30.77 €/MWh and SI was 1060 €/kW. Compared to this basic case, the BESP for CFBG with normal burner were 24.29, 28.57and 32.97 €/MWh, the SI was 1169 €/kW, an increase of 10.3%; the BESP for CFBG with COSTAIR were 25.72, 30.17and 34.62 €/MWh. The SI was 1244 €/kW, an increase of 17.4%; the BESP for CFBG with FLOX were 26.55, 30.99 and 35.44 €/MWh. The SI was 1284 €/kWe, an increase of 21.1%. The sensitivity analyses showed that the CFBG with FLOX system had the highest BESP and SI; the CFBG with COSTAIR had the medium; the CFBG with normal burner were lower, and the conventional CFBC had the lowest. But the CFBG with COSTAIR and the CFBG with FLOX had the lowest NOx emissions which would benefit the environment.
S-burner – Techno-economic Analysis of 12 MWe CFBC Power Plant
The ECLIPSE was used to simulate a 12 MWe Circulating Fluidized Bed Combustion (CFBC) power plant fuelled by the reference fuels with a range of combustion technologies: 1) a standard conventional Circulating Fluidized Bed Combustion (CFBC); 2) a Circulating Fluidized Bed Gasifier (CFBG) with a conventional burner; 3) a Circulating Fluidized Bed Gasifier (CFBG) with a flameless oxidation (FLOX) burner; and 4) a Circulating Fluidized Bed Gasifier (CFBG) with a staged combustion (COSTAIR) burner. The solid biomass fuel used in the investigation are from the project report D1.1, “Market Study Fuels”; the report of D1.2 “Report with analysis data” and the first year activity report. Table 21 shows the results of the fuel consumed for the heat/power plants from the simulation using ECLIPSE. The results show that the fuel consumptions are from 233 to 819 tonnes/day for the 12 MWe power plant; the average is 272 tonnes/day.
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Table 21 Fuels consumed for the heat/power plant
12 MWe Power Plant
Fuel Flow
(daf, Tonnes/day) Fuel Flow
(raw, Tonnes/day)
S1 231 274
S2 226 247
S3 265 319
S4 233 288
S5 207 233
Straw 216 255
Wood-REF 205 291 The technical results of the 4 systems are summarised in Table 22.
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Table 22 Technical and Emission Results for 12 MWe Power Generation Plants (fuel S1)
Combustion Gasification + normal buner
Gasification +FLOX burner
Gasification +COSTAIR
burner
FD-Fan 496 421 751 751
ID-Fan 80 70 109 109
Ash Box 16 16 16 16
Gas Cleaning 1 1 1 1
Ash Convey 14 14 14 14
Wood-Convey (S1) 155 155 155 155
HP Pump 206 209 209 209
LP Pump 1 2 1 1
Total 970 888 1256 1257
IP Turbine 6426 6521 6525 6526
LP Turbine 7261 7349 7359 7358
Electric Process 12717 12982 12628 12628
Electric Utility 231 234 234 234
Net Electric (kWe) 12486 12748 12393 12393 Fuel Flow daf (Ton/day) 216 216 216 216
Biofuel Type S1 S1 S1 S1
Steam Cycle (bar / ºC) 80/480 80/480 80/480 80/480
Thermal Input LHV 43 43 43 43
Thermal Input HHV 47 47 47 47
Efficiency LHV % 28.93 29.54 28.72 28.72
Efficiency HHV % 26.36 26.91 26.16 26.16
Exhaust Gas Temp 123 123 132 133 Exhaust Gas Flow kg/s 22 19 19 19
CO2 g/kWh 1295 1278 1314 1314
SO2 mg/Nm3 209 244 244 244
CO mg/Nm3 51 50 30 30
NOx mg/Nm3 211 210 105 126
O2 (dry) Vol % 5.47 1.51 1.46 1.52
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Economic assessment is carried out by ECLIPSE. Additional costs due to incorporating the FLOX or the COSTAIR burners in each system were considered, but in fact it was found that no significant overall increase in costs would be necessary for the manufacture, installation or operation of such burners. The results for the 12 MWe CFBC power plants determined in the economic analysis are shown in Table 23. The results show that the total capital investment is 32.232 Million € and the specific investment 2588 €/kW for the case of conventional CFBC power plant. The total capital investment is 34.670 Million € and the specific investment 2740 €/kW for the power plant of CFBG plus normal syngas burner. The total capital investment is 35.280 Million € and the specific investment 2788 €/kW for the power plant of CFBG plus FLOX syngas burner. And the total capital investment is 34.975 Million € and the specific investment 2764 €/kW for the power plant of CFBG plus COSTAIR syngas burner. The cost for the CFBG plus FLOX plant is the highest, but it has the best effect to reduce NOx and CO emissions, as seen in Table 22 and Table 23. The cost for CFBG plus COSTAIR plant comes the second and it has also good effect on NOx and CO reductions. The cost of CFBG plus normal burner plant is the third one and has no NOx and CO emission reduction effect. The cost of normal CFBC plant is the lowest, but it emits high NOx and CO.
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Table 23 Economic Results for 12 MWe Biofuel Electricity Generation Plants
Combustion GasificationGasification
+FLOX Gasification +COSTAIR
Capital cost Million € Million € Million € Million €
Fuel preparation 3.052 3.052 3.052 3.052
Dryer 0 0 0 0
Gasifier (+ boiler) 0 8.881 8.881 8.881
Hot gas cleaning 0 0.736 0.736 0.736
FLOX burner 0 0 0.533 0
COSTAIR burner 0 0 0 0.266
Boiler 7.486 0 0 0
Cooling tower 0.169 0.169 0.169 0.169
Baghouse 0.32 0.32 0.32 0.32
Boiler feed water/deaerator 0.944 0.944 0.944 0.944
Steam turbine/Generator 2.495 2.495 2.495 2.495
Cooling system 1.113 1.113 1.113 1.113
BoP 4.603 4.603 4.603 4.603
General plant facitities 5.227 5.227 5.227 5.227
Engineering fees 0.118 0.118 0.118 0.118
Initial consumables 0.037 0.037 0.037 0.037
Startup costs 0.895 0.895 0.895 0.895
Inventory capital 0.189 0.189 0.189 0.189
Misc. costs 1.527 1.527 1.527 1.527
Total plant cost 28.175 30.306 30.839 30.572
Capital fees (%) 2 2 2 2
Contingence allowance (%) 10 10 10 10
Working capital (%) 2 2 2 2
The total capital investment 32.232 34.670 35.280 34.975
Specific Investment (€/kW) 2588 2740 2788 2764 The above assessment of alternative NOx reduction technologies to the conventional CFBC power plant and CFBG plus normal burner power plant were successfully completed using the ECLIPSE process simulator.
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Compared to the conventional CFBC plant, the NOx emissions for CFBG with normal burner reduced by 0%; for CFBG with COSTAIR reduced by 40%; for CFBG with FLOX reduced by 50%. The CO emissions for CFBG with normal burner reduced by 0%, for CFBG with COSTAIR reduced 40%; for CFBG with FLOX reduced 41%. With a wood chip price of 0, 20 and 40 €/tonne, the BESP for the CFBC plant were 53.50, 67.94 and 82.37 €/MWh and SI was 2588 €/kW. Compared to this basic case, the BESP for the plant of CFBG plus normal burner were 56.64, 70.85 and 85.06 €/MWh, the SI was 2740 €/kW, an increase of 5.9%; the BESP for COSTAIR were 57.14, 71.35 and 85.55 €/MWh. The SI was 2764 €/kW, an increase of 6.8%; the BESP for FLOX were 57.64, 71.85 and 86.05 €/MWh. The SI was 2788 €/kWe, an increase of 7.7%. The sensitivity analyses showed that FLOX system had the highest BESP and SI; COSTAIR had the medium, CFBG plus normal burner was lower, and the simple combustion had the lowest. But the COSTAIR and FLOX have the lowest NOx emissions which will benefit the environment. The above results of electricity selling prices are comparable with those found in the literature [17] and [18]. Bibliography
[1] Williams BC., The development of the ECLIPSE simulator and its application to the techno-economic assessment of clean fossil fuel power generation systems, DPhil Thesis, Energy Research Centre, University of Ulster, Coleraine, N.I. 1994.
[2] McMullan, JT; Williams, BC., Development of Computer Models for the Simulation of
Coal Liquefaction Processes. International Journal of Energy Research, 1994, 18 (2), p117-122.
[3] Williams BC, McMullan JT. Techno-economic analysis of fuel conversion and power
generation systems – the development of a portable chemical process simulator with capital cost and economic analysis capabilities, International Journal of Energy Research, 1996; 20(2):125-142.
[4] Willams BC, McMullan JT. In: Imariso, Bemtgen, editors. Progress in synthetic fuels,
London: Graham and Trotman, 1988. p. 183–9. [5] ECLIPSE Process Simulator, Energy Research Centre, University of Ulster, Jordanstown,
N.I., 1992. [6] McMullan, J.T., Williams, B.C., Campbell, P., McIlveen-Wright, D., Techno-economic
Assessment Studies of Fossil Fuel and Fuel Wood Power Generation Technologies, Joule II – Programme R&D in Clean Coal Technology, European Commission, ISBN: 84-7834-280-X, 1995.
[7] McCahey, S.; McMullan, J.T.; Williams, B.C., Techno-economic analysis of NOx reduction technologies in p.f. boilers, Fuel, v 78, n 14, Nov, 1999, p 1771-1778 [8] McGowan, Thomas F., NOx Control for Stationary Sources and Utility Applications,
Proceedings of the 2003 International Joint Power Generation Conference, 2003, p 677-685
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[9] European Communities, Directive 2001/80/EC of the European Parliament and of the Council of 23 October 2001 on the limitation of emissions of certain pollutants into the air from large combustion plants, Official Journal of the European Communities, 27.11.2001 p.L309/1 – L309/21
[10] Werther, J. , Hartge, E.-U., Lücke, K., Fehr, M., Amand, L.-E., Leckner, B., New Air-
Staging Techniques for Co-Combustion in Fluidized-Bed Combustors, VGB-Conference, Research for Power Plant Technology 2000, 10 – 12 October 2000, Düsseldorf, Germany
[11] Flamme, M., Low NOx combustion technologies for high temperature applications,
Energy Conversion and Management, 42 (2001), p 1919 – 1935 [12] Wünning, J.G., Flameless Combustion in the Thermal Process Technology, Second
International Seminar on High Temperature Combustion in Stockholm – Sweden, January 17 th-18th, 2000
[13] Matovic1,M. D., Grandmaison, E. W., Miao Z., Fleck, B., Mixing Patterns in
a.Multiple-Jet Ultra Low NOx CGRI Natural Gas Burner, Fuel Selection Issues for Industrial Combustion Processes Achieving Sustainability, Environmental and Economic Objectives, 2002 AFRC Spring International Combustion Symposium 8th –10th May, 2002 Ottawa, Canada
[14] Trento, L., Smabastian, P.L., Development and assessment of an advanced flameless
oxidation burner for very low NOx emissions, Fourth year seminar proceedings 2001 [15] Jozewicz, W., Cost of Selective Catalytic Reduction (SCR) Application for NOx Control
on Coal-fired Boilers, Project Summary, United States Environmental Protection Agency, National Risk Management Research Laboratory Cincinnati, OH 45268, Research and Development EPA/600/SR-01/087 January 2002
[16] USA Environmental Protection Agency, Air Pollution Control Technology Fact Sheet,
EPA-452/F03-032, 2003, www.epa.gov/ttn/catc/dir1/fscr.pdf [17] Imperial College London, Centre for Energy Policy and Technology and E4tech (UK)
Ltd, Authors: Ausilio Bauen, Jeremy Woods and Rebecca Hailes, Bioelectricity Vision: Achieving 15% of Electricity from Biomass in OECD Countries by 2020, April 2004, http://www.wwf.at/downloads/WWF_biomassreportfinal_25.4.pdf
[18] Klaus Skytte_, Peter Meibom, Thomas Capral Henriksen, Electricity from biomass in the
European union—With or without biomass import, Biomass and Bioenergy, vol 30, P.385–392, 2006
1.3.6.2 Market Evaluation Based on the results of the market study and on the investment and operation costs of the burners UU will prepare a study of the global market potential of the new technology. This study will detect the most promising markets and the number of burners which can be sold. When designing a power/heat generation plant for a particular mixture of biofuels, one must be sure that the fuels considered, or something equivalent, should be available over the lifetime of the power/heat plants, which could be 25 to 30 years. There are several factors
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which can influence the availability of the fuels for the system. The amounts of these materials, as well as a few others, generated in Europe, and the factors affecting their availability for use in energy recovery, is one of the subjects of this report. The power/heat plants for the application of FLOX/COSTAIR burners in this project will be fuelled from a mixture of biofuels, mainly from the bio-refineries, e.g. wood (chips, pellets or sawdust), solid residues from grain mills; gas from digesters (biogas), gas from a CFB gasifier (syngas – this is also mainly from solid biofuels); liquid fuels such as rape oil, etc. The amount of biofuels occurring, whether locally or nationally, is not the only factor in determining how much could be used for energy recovery. Waste strategies put energy recovery very low on the waste pyramid, coming just above landfilling of waste and below re-use, recycle. There are legislations on waste, on emissions reduction and on renewable energy, all of which will have an impact on the availability of wastes from bio-refineries and the other resources for energy recovery. In addition, trade in solid biofuels and wastes have developed on a local and international scale, which also complicates any picture of biofuel availability. The study has shown that there are several national and EU initiatives that are designed to encourage the use of biofuels from the waste materials, also those to encourage the development of the use of RES for power/heat generation and mechanisms to reduce the emissions of greenhouse gases, promote energy efficiency and the use of CHP, all of which could have some effect on the availability of biofuels suitable for power/heat generation. The increase in local, national and international trade in biofuels could allow a wider distribution of the biofuels as well. This would make a wider availability of biofuels on medium and long-term for the power/heat plants which would be a wider market for the application of FLOX/COSTAIR burners. Information on the amount of biofuels available, and the location where it is produced, are estimated. Based on the biofuels available, the efficiencies and the fuel consumption of the heat boiler and the power plant defined in the project, the numbers of FLOX/COSTAIR burners can be sold are estimated, assuming that 50% of the available biofuels are consumed by the 1 MW heat boilers and that 50% of the fuels are used by the 12 MWe power plants. The results are summarised as following: 6.3.4.1 The estimated numbers of FLOX/COSTAIR burners can be sold for 1 MW heat only boilers in EU countries
With a total natural gas supply of 289,785 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 180,317 with 50% of biofuels used by 1 MW heat only boilers. With a total landfill gas supply of 5,072 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 3,061 with 50% of biofuels used by 1 MW heat only boilers. With a total biogas supply of 4,089 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 2,468 with 50% of biofuels used by 1 MW heat only boilers.
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With a total Light fuel oil supply of 85,432 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 51,558 with 50% of biofuels used by 1 MW heat only boilers. With a total bio crude oil supply of 4,758 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 2,872 with 50% of biofuels used by 1 MW heat only boilers. With a total bioethanol supply of 2,188 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 1,320 with 50% of biofuels used by 1 MW heat only boilers. With a total biodiesel supply of 879 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 530 with 50% of biofuels used by 1 MW heat only boilers. With a total black liquor supply of 10,573 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 6,381 with 50% of biofuels used by 1 MW heat only boilers. With a total agricultural residues supply of 32,729 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 19,752 with 50% of biofuels used by 1 MW heat only boilers. With a total industrial residues supply of 12,942 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 7,810 with 50% of biofuels used by 1 MW heat only boilers. With a total wet manure supply of 14,145 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 8,537 with 50% of biofuels used by 1 MW heat only boilers. With a total dry manure supply of 2,226 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 1,343 with 50% of biofuels used by 1 MW heat only boilers. With a total biodegradable municipal waste (landfill) supply of 55,642 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 33,580 with 50% of biofuels used by 1 MW heat only boilers. With a total biodegradable municipal waste (Incineration)supply of 24,108 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 14,549 with 50% of biofuels used by 1 MW heat only boilers. With a total demolition wood supply of 5,841 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 3,525 with 50% of biofuels used by 1 MW heat only boilers. With a total sewage sludge supply of 2,138 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 1,290 with 50% of biofuels used by 1 MW heat only boilers.
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With a total wood fuels supply of 23,802 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 14,365 with 50% of biofuels used by 1 MW heat only boilers. With a total Wood energy consumption of 53,964 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 32,567 with 50% of biofuels used by 1 MW heat only boilers. The estimated numbers of FLOX/COSTAIR burners that can be sold for 12 MWe power plants
With a total natural gas supply of 289,785 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners that may be sold in European countries are 4,676 with 50% of biofuels used by 12 MWe power plants. With a total landfill gas supply of 5,072 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners that may be sold in European countries are 79 with 50% of biofuels used by 12 MWe power plants. With a total biogas supply of 4,089 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners that may be sold in European countries are 64 with 50% of biofuels used by 12 MWe power plants. With a total Light fuel oil supply of 85,432 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 1,337 with 50% of biofuels used by 12 MWe power plants. With a total bio crude oil supply of 4,758 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 74 with 50% of biofuels used by 12 MWe power plants. With a total bioethanol supply of 2,188 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 34 with 50% of biofuels used by 12 MWe power plants. With a total biodiesel supply of 879 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 14 with 50% of biofuels used by 12 MWe power plants. With a total black liquor supply of 10,573 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 165 with 50% of biofuels used by 12 MWe power plants. With a total agricultural residues supply of 32,729 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 512 with 50% of biofuels used by 12 MWe power plants. With a total industrial residues supply of 12,942 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 203 with 50% of biofuels used by 12 MWe power plants.
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With a total wet manure supply of 14,145 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 221 with 50% of biofuels used by 12 MWe power plants. With a total dry manure supply of 2,226 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 35 with 50% of biofuels used by 12 MWe power plants. With a total biodegradable municipal waste (landfill) supply of 55,642 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 871 with 50% of biofuels used by 12 MWe power plants. With a total biodegradable municipal waste (Incineration) supply of 24,108 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 377 with 50% of biofuels used by 12 MWe power plants. With a total demolition wood supply of 5,841 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 91 with 50% of biofuels used by 12 MWe power plants. With a total sewage sludge supply of 2,138 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners may be sold in European countries are 33 with 50% of biofuels used by 12 MWe power plants. With a total wood fuels supply of 23,802 ktoe (1000 ton of oil equivalent), the total estimated numbers of FLOX and COSTAIR burners that may be sold in European countries are 373 with 50% of biofuels used by 12 MWe power plants. With a total wood energy consumption of 53,964 ktoe (1000 ton of oil equivalent), the total estimated number of FLOX and COSTAIR burners that may be sold in European countries are 845 with 50% of biofuels used by 12 MWe power plants. From these estimates it is clear that there is a considerable potential for the exploitation of the market for the three selected applications of systems using the FLOX or COSTAIR burners, based on biofuel availability and the factors driving this fuel availability. The estimated numbers here are obviously an upper limit for the potential market for the novel burners, since there will be a range of other uses for these
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2 Dissemination and use
2.1 Publishable results
Exploitable results
The new burner technologies enable to burn fuels with low calorific values and thus broaden the field of possible bio-fuels in the energy production. Particularly residues from biorefineries can be used in the new combustion technology. Promising biorefineries were identified during a market study at the beginning of the project, among them breweries, pulp and paper industry, saw mills, sugar/bio-ethanol industry. But also off-gases from industrial processes, landfill or mining sites can be utilised with the new burners. In order to apply also slurrys and wet biomass to thermal conversion the aspects of storage, milling, feeding and pre-drying of such fuels has been investigated. Different concepts for drying of wood fuels for use in small-scale heat plants (< 10MW) were tested. The work is very important for this type of industry were different types of residues are produced that are potential fuels for heat generation in small scale. Most combustion equipment is designed for specific fuel types and one of the most important combustion parameter in biomass combustion is fuel moisture. If there was an effective and cheap system that could pre-treat fuels with different fuel moisture content with waste heat, then this would made it possible for the industry to use more of its own residues for heat production. In many cases this would mean that biomass fuels can replace fossil fuels to a larger extent with better economy and less environmental impact. The investigations related to an adapted FLOX-burner for LCV gases has shown that gases with heating values down to 2.5 MJ/m3 can be utilised. This is a remarkable improvement to existing burner technologies. Parallel activities related to solid residues did result in an optimised combustion system for low-grade biomasses by integrating a newly developed FLOX-burner for the direct combustion of hot and tar-loaded LCV gases. This combustion system showed several benefits compared to the conventional system, e.g. better burnout, stable operation and higher efficiency. Regarding the utilisation of solid biomasses with high nitrogen content the project results have show that the application of the FLOX technologies is not sufficiently reducing the NO emissions. Therefore, the development of an air staged FLOX-burner for solid biomasses was brought forward. The objective of this work was to show how moist wood fuels can be made technically and economically available for small scale heat generation where dry fuels so far has been the only option. The work has included both theoretical and experimental work. A further advanced combustion technology, the continuous air-staging (COSTAIR), was adapted within the project to the combustion of LCV gases. Furthermore, a state-of-the-art burner for biomass fuels was developed where a BIOSWIRL gasifier was used together with a burner developed from the COSTAIR concept. The COSTAIR concept is developed for increased control of addition of air to the combustible gas. This makes the concept suitable for use in a biomass combustion system for minimisation of NOx-emissions.
Within the BIO-PRO project, a new on-line heating value analyser for a wide variety of low calorific value gases was developed. The analyser is aimed at forming a part of a feed-forward
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burner control loop in order to anticipate to the changing heating value of the incoming fuel gas, with the target to maintain the (very) low pollutant emissions of the novel flameless oxidation combustion technology (CO and NOx in particular). This analyser can be used for the control of boilers, gas engines, fuel cells operation on different types of gas. A CFD model of the LCV-FLOX-burner was set-up and simulations for this flameless oxidation burner type were performed. This analysis can be used to improve the CFD models extending the simulations to off-specification fuels for which no data are available in literature. This approach can be used to explain qualitatively the difference between syngas and natural gas combustion. In particular it is found that in the case of syngas combustion the lower release of chemical energy results in reduced turbulence intensity. Due to this phenomenon the regime of combustion can be slightly dependent on the fuel used with consequence on flame stability, flame thickness and on the mechanism of turbulence flame interaction. Several flameless combustion experiments were conducted to establish improved boundary conditions for the combustor modeling and to obtain a better insight into burner control strategies aimed at minimizing CO and NO. These experiments showed very low CO and NO concentration values using the burner on syngas. CO concentrations well below 30 mg/mn
3 (even below 10 mg/mn
3 at 3% O2) were obtained with a hydrogen rich gas. An outlet temperature control strategy was applied acting on the (secondary) air of wall cooling. At the end of the project three prototype FLOX-burners were tested: unstaged burner at FW site, air-staged FLOX-burner at ZAMER site, FLOX-flare for landfill gases at a landfill site in Ticino/Switzerland. Summarizing the experiences of the first FLOX burner tests using product gas from a 1.5 MW biomass gasifier as fuel, the burner operation was fully reliable throughout the 176-hour test period. Carbon monoxide emissions were negligible, but the NOx emissions were at the same level as with the old burner of the facility. This has been attributed to NOx formation from reduced nitrogen species in the syngas (mainly NH3, HCN), suppression of which would require further measures. Other partners have studied the issue later on in the project. The commissioning and first tests of later developed air-staged FLOX-burner were performed close to the end of the project. Unfortunately because of problems with switching from start-up state to normal burner operation (gasifier products firing) there was not possible to operate the burner properly. After applying the modification at burner design there were performed further investigations at Zamer’s facility. During these tests strong pulsations in the burner occurred. During scheduled test runs there was not possible to investigate this problem deeply. Probably these pulsations caused damage of one of burners elements – ceramic tube that works as combustion stabiliser. Decreasing of NOx emission with decreasing of primary air flow and increasing of secondary air flow (understoichiometric operation in the first stage) can be noticed. Still, monitoring time of the burner performance was too short to investigate the burner more in detail and to identify the best operation conditions. Nevertheless, the commissioning of the air-staged burner was successful and the reduction potential for NOx emissions was shown. For a more reliable burner operation further optimisations of the burner integration at ZAMER test site were necessary, but not possible within the timeframe of the project. The FLOX-flare is now in continuous service since November 8th 2006. The unit combusts 50 m3n landfill gas per hour, containing 9 to 11% CH4. According to experience, the unit is estimated to be capable to burn land-fill gas down to 6.0% CH4 without changing the design. The measured NOx emissions of the field test unit are 5 to 20 mg/m3
n @ 3% O2. The CO-emissions can be held between 0 to 20 mg/m3
n @ 3% O2, but through the need of secondary cooling air, the combustion process is slowed down after passing half of the residence time in the combustion chamber. Therefore, CO emissions can vary up to 100 mg/m3
n @ 3% O2. For
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further products, these problems are already solved. Therefore it can be stated, that the adopted burner overbids clearly the project targets of 50% NOx emission reduction compared to state of art (would be 40 mg/m3
n @ 3% O2) and reduction of CO-emission below 20 mg/m3
n @ 3% O2. Besides landfill sites the burner can also be applied to biorefineries, e.g. for the utilisation of off-gases from the methanisation of biogas to be fed into the gas-grid. Information about the project as well as contact details of the participating partners is available on the project website www.eu-projects.de/bio-pro.
Practical applications
The new burner technologies can be applied for the energy production in all conversion processes that use fuels and chemicals produced from biomass. Another application can be the integration of the new burners in power plants as well as already existing biomass combustion systems to ensure a low emission combustion of bio-fuels. The biorefinery technology as well as other emerging technologies like bio-ethanol production is under development all over the world. One major drawback for these technologies is that they still need a considerable fossil fuel input to generate process heat for chemical reactors, rectification etc. Bio-ethanol production e.g. generates only a 30% renewable energy surplus, comparing the generated ethanol to the fossil fuel energy input. These figures show that there is a considerable need for the envisaged technology to utilise the process residues for energy generation within the process. The BIO-PRO burner technology will be able to serve this global market. Therefore, it does not only support European bio-refinery technology, it generates its own global market. Beside this dedicated bio-refinery market the technology offers further market potentials, especially for the CHP biomass technologies: Micro gas turbines: Both burner technologies are under development for gas turbines
utilising natural gas. Their intrinsic advantage of fuel flexibility means that they will be of considerable use to operate gas turbines with bio-fuels like biogas, BCO, producer gas etc.
Oil- and gas burner retrofit: Retrofitting Oil and gas fired district heating or CHP boilers with bio-fuel technology offers an economic way to increase the utilisation of renewable fuels. In this particular market the new technology can be cheaper, compared to fuel oil and natural gas if it is possible to reduce retrofit measures to a minimum. This is feasible with the BIO-PRO technology which overcomes the main barrier of insufficient residence times for particle burn out in such boilers.
Externally fired combined cycles: FLOX burners are already available with so called radiation tubes for indirect process heating. Combustion gases are totally separated from the heated surrounding. This technology can be transferred to the BIO-PRO burners in order to facilitate externally fired gas turbine cycles offering a considerable efficiency increase compared to directly fired micro gas turbines.
Utilization of off-gases: The utilization of LCV gases evolved from industrial processes, landfill or mining sites is becoming a further field of application for BIO-PRO burner. Due to the decreasing quality of these gases their energetic utilization is becoming limited with conventional burner systems. As these gases can still contain considerable amounts of methane their further utilization will contribute both to the reduction of greenhouse gases (CH4 has a four times higher greenhouse gas potential as CO2) and increase of the energetic and economic efficiency of these processes.
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Need for further development work
Besides the successful adaptation of both combustion technologies (FLOX and COSTAIR) low calorific value gas (LCV gas) and several operation benefits that were identified (combustion of LCV gas of very low quality, operation at low excess oxygen, very low CO emissions, etc.) there are still limitations of the combustion technologies regarding the utilisation of nitrogen rich fuels. Although thermal NOx emission can be diminished the NOx emissions generated from the fuel-N can not be reduced. In order to utilize bio-residues with a high content on nitrogen the integration of a reduction zone within the burners is reasonable. First steps towards the development of a staged FLOX-burner were undertaken at the end of the project. Still the consortium agreed that the development of a staged burner needs to be investigated in a follow-up project. The tests have shown that there is still a lack of knowledge about the NOx reduction process (chemical pathways, temperature range and residence time needed, mixing conditions,…) and the basics of the NOx reduction process are still insufficiently understood within the research community. This is a further topic that needs to be investigated. Need for further collaboration
Need of further research and development in fuel bound nitrogen conversion to NOx during flameless oxidation, relevant as several (biomass) fuels contain appreciable amounts of this nitrogen in their structure and conversion to syngas leads to NH3-HCN (HNCO). Further collaboration in this area is aimed at by TUD. This holds for both G-L combustion technology as well as study of devolatilization of different biomasses relevant for the G-S combustion technology studied within this project. GWI and TPS are planning to continue their collaboration to bring the concept of continuous staged air (COSTAIR) to the market. The focus will be on two development stages:
a) further optimisation of up-scaled TPS Bioswirl burner b) eventually adapting the original COSTAIR concept to the TPS gasifier
This work will be managed by GWI and TPS in the future to exploit the results of BioPro project to the market. TPS are planning to send in application to the Swedish Energy Agency for funding of project for further development/demonstration of the Bioswirl-gasifier/burner for reduction of NOx-emissions from biomass fuels. Collaboration is wanted in the field of experimental characterization of different biomass fuels regarding release of fuel-bound nitrogen from pulverized biomass fuels at high heating rates, that is to say for conditions relevant for suspension firing of pulverized biomass fuels. Further collaboration is planned by USTUTT to develop an air staged FLOX-burner for the utilization of nitrogen rich fuels. Besides the special requirements for the design of such a burner the NO formation process from NO-precursors (NH3, HCN,…) has furthermore to be investigated as first results indicate that the conversion of NO-precursors is enhanced by the flameless oxidation.
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Contact details
Project coordinator: Roland Berger Institute of Process Engineering and Power Plant Technology University of Stuttgart Pfaffenwaldring 23 D- 70569 Stuttgart E-mail: [email protected] Tel.: +49 (0) 711 685 63492
2.2 Overview of results’ exploitation and use potential In the following table an overview of the exploitable results and the potential of use are given.
Results generated (short description)
Owner(s) (name of the legal entity)
Sector(s) of Application
Exploitation / use potential measures
Timetable for use or
exploitation Low Caloric Value Burner for gaseous fuels below 2.5 MJ/m3
WS Treatment of industrial exhausts Landfill gas Mine gas
Products of e-flox and other licensees of WS in cooperation with FATSE
Starting 2007
Staged Low-NOx-FLOX burner for solid fuels
FATSE Solid biomass boilers, solid biomass CHP
Application in on-going R&D-project and product development
Since 2006
Low-NOx-FLOX burner for liquid bio-fuels
FATSE Process heat from bio-refinery-waste. Oil-burner for CHP-applications
Negotiations with CHP-developer on- going
Not planned yet
FLOX-burner for hot and low calorific value gases generated from biomass in a previous gasification step
USTUTT Solid biomass boilers, solid biomass CHP, Process heat from bio-refinery-waste
Conference, product of e-flox and other licensees of WS
Starting 2007
Development of an on-line fuel gas analyser (OFGA) for combustible gases with different composition and heating value
TUD Control of boilers,gas engines,gas turbines,fuel cells operating on different types of gas (e.g. from biomass, in biorefineries etc.)
Search by the Dutch ´´Octrooicentrum Rijswijk´´, based on result, possibly patent application will be formulated
By May 2007 search result available
Experiments on LCV-MCV gas using FLOXTM burner, leading to (very) low NO,CO emissions
TUD Gas turbine, boiler sector Research and Development
Conference/journal paper
2007-2008
Efficient burner for low calorific gases
GWI Landfill gas, biomass gasification gas, mine gas, biogas
First applications for biomass gasification gas and biogas, further R&D-projects are ongoing
Starting 2007
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2.3 Innovation related activities The most important developments for FATSE and WS in this project are the Low-Caloric-Value (LCV) burner and the solid biomass FLOX burner. Both have directly lead to the development of industrial products. For the first, details will be mentioned below. For the second, the application of a staged FLOX burner for solid biomass, developed by FATSE within Bio-Pro (Tasks 2.3/2.5 and 3.4) is part of the on-going EUREKA-project “Biopoly Heat”. The product will be a low-NOx, dioxine-emission-free boiler for non-wood bio-pellets. Through the great success of Bio-Pro by creating a spin-off of USTUTT and WS, the e-flox GmbH, the interest of such Bio-FLOX related products could be amplified. E-flox GmbH is a company dedicated to the implementation of FLOX technology in energy-production related objects and/or the treatment of burnable wastes of bio-refineries and landfills. Contacts with potential users exist since the publication of the LCV-ability in spring 2005 and have lead to 3 pilot projects to be established in 2007. The industrial partner Verdesis Suisse SA started to contact FATSE after reading a Bio-Pro press release in an electronic newsletter 2005. 2007, three biogas-plants will be equipped with a LCV-FLOX-burner burning the exhaust gas from pressure-swing-absorbtion (PSA) methanisation systems. FATSE has established a co-operation and a further R&D-project with e-flox and Verdesis. Market and exploitation:
o The market sectors for LCV flaring systems for landfills, mines with lowering gas quality and methanisation plants for gas-grid-feeding biogas production have a volume of each 500 MW (200 M€) in Germany only. It is estimated to be at least 4 times as much in the EU and especially in mines of Poland, Ukraine and Czech Republic. Establishing emission trade projects as done with the field test plant, the mentioned 1.5 GW in Germany equals to a yearly turnover of 250 M€ at 10 €/t CO2-equivalent.
o There are two possibly competing products identified. However they base on a technology which tends to have a much shorter life cycle and they have not yet proofed proper service with heat values lower than 3.6 MJ/m3.
o For a pilot market, the LCV-FLOX-Flare/combustor is at time a unique selling argument. Switzerland allows only methan-emission-free plants to convert biogas to car-fuel to be considered in CO2-oblications related calculations.
The FLOX principle and the name FLOX are patented by WS Wärmeprozesstechnik GmbH. The Intellectual Property Rights of the innovations are in the hands of WS and the spin-off company e-flox GmbH. protection measures (patents, design rights, database rights, plant varieties…). Additionally a consortium agreement exists between Verdesis Suisse SA, the above mentioned and FATSE, how to cooperate in a defined pilot market and on other markets. It can be stated that the name “FLOX”, which had been existing already since 1992 within the high temperature process burner industry, could be spread rapidly among industrial branches, which didn’t know this word before Bio-Pro. USTUTT developed in co-operation with WS FLOX-burner that is directly integrated in a fixed-bed gasifier. This burner shows several benefits for the utilisation of low-grade biomass. As mentioned above a spin-off company of USTUTT and WS was founded, the e-flox GmbH. E-flox GmbH is a company dedicated to the implementation of FLOX technology in energy-production related objects and/or the treatment of burnable wastes of bio-refineries and landfills. Regarding development of the On-line Fuel Gas Analyser (OFGA), deliverable 4.1 (confidential report) TUD has investigated this in the framework of this project and not before. TUD made an appointment with the Dutch Octrooicentrum situated at Rijswijk to perform a patent search, to
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study the possible patent application in view of possible obstacles-existence or recent development of competing technologies (could be in the area of Wobbe Index measurement devices). The result of this search is expected soon, ultimately in May 2007. Depending on the result of the current state of this development work and industrial (SME) interest in relation to other developments and needs in this area, a path towards patenting the technology will be followed. The timeframe towards patenting at a positive outcome of the search and following investigation on real interest of industry, could be about 1-2 years. GWI is exploiting the project results by two ways: directly by giving licences to industrial companies und directly by joining research group in burner development and applications to several industrial sectors. Furthermore, GWI is disseminating the project results through presenting them on national and international conferences to acquire potential users of interest in the innovative burner applications for low calorific gases. GWI is already using the achieved project results in running research project to find new innovation features regarding efficient energy use and burner technologies. New ideas will be protected by patent applications.
2.4 Report for engaging with the public FATSE The following list is a summary of publications and other PR-efforts within the project Bio-Pro and its products so far. Scientifical papers in conference documents and related to presentations:
• M. Schmid (FATSE), J.G. Wünning (WS), R. Berger (USTUTT): “New horizons for FLOX®-technology for biomass fuels”. 6th International Symposium on High Temperature Air Combustion and Gasification 2005, Essen.
• M. Schmid (FATSE), C. K. Gaegauf (FATSE), Daniel Hegele (Hoval Werke AG);
Joachim G. Wünning (WS); „Flammlose Verbrennung zur NOx-Minderung: Konzept und Anwendung für automatische Holzfeuerungen“, 9. Holzenergie-Symposium, ETH Zürich, october 2006
• M. Schmid (FATSE), J. Roth (Roth und Partner GmbH); “Gasverwertung mit
Mikroturbinen am Beispiel der Deponie Freiburg”, Presentation at “Deponiegas 2007”, Trier January 2007
• M. Schmid (FATSE), C. K. Gaegauf (FATSE); “FLOX-combustor for liquid and gaseous bio-residues”, presentation at workshop „New burner for bio-residues“, University Stuttgart, February 2007
• M. Bichsel (TDU GmbH), „FLOX®-Verbrennung für Schwachgas von Deponien“; main contribution at the „Generalversammlung des Verbandes der Betriebsleiter und Betreiber Schweizerischer Abfallbehandlungsanlagen VBSA“, Mai 2007-04-11
Publications in Newspapers and other periodic Printmedia:
• M. Schmid (FATSE), Beat Näf (Verdesis Suisse SA); “Flammenlose Oxidation – mehr als nur Low-NOx – neue Horizonte für Schwachgasnutzung, Bioenergie und Gasturbinen.“; GWA 12-05, Zeitung des schweizerischen Verein des Gas- und Wasserfaches SVGW, 2005
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• R. Berger (USTUTT), M. Schmid (FATSE), J.G. Wünning (WS); „Low-NOx lean-gas combustion with flameless oxidation”; Gaswärme International, Vulkan-Verlag Essen, 2005
• M. Schmid, A. Killenberger (FATSE); „Weltrekord Verdacht mit
Klimaschutzpotential“, Pressrelease published 15-fold by swiss newspaper press, Langenbruck, 2005
• M. Schmid (FATSE), Vinzent Schild (Axpo), „Pragmatiker im Einsatz für
umweltverträgliche Technologien“, Naturstrom-Newsletter (Axpo), Issue 1-2006 • M. Schmid (FATSE) Emanuele Centonze (ECSA), Kathrin Dellantonio (myclimate),
„Tessiner Unternehmer investiert in Klimaschutz im Tessin“; press-release 23-11-06 of MyClimate, Zürich 2007
• M. Schmid (FATSE), H.P. Zumsteg (FATSE), „Weltbewegende Technik zum
Klimaschutz im Tessin“, press-release 19-01-07 of FATSE, published in Swiss newspaper press and via the newsletter of energiecluster.ch; Langenbruck 2007
Flyer, Posters and short communication for exhibitions and visitors of the institute
• Energie aus der Biogasaufbereitung (1 page A4) • Saubere Biomasse-Verbrennungstechnik (1 page A4) • EU-Forschungsprogramm Bio-Pro (1 page A4, downloadable as pdf) • Schwachgasnutzung und –abfackelung (1 page A4, downloadable as pdf)
TUD: TUD has published a summary of the project description on its website (www.pe.tudelft.nl, clicking to the Energy Technology Section, Research). Posters have been presented at the Dutch Combura symposium 2005 and 2006, held at Nieuwegein (with only short abstracts in proceedings) and at the HiTAC2005 conference held in Essen (Germany). TUD plans to submit another conference-journal paper based on the experimental work on the FLOXTM combustor. Also, in view of its role as an educating institute, TUD plans to teach the principles of flameless oxidation of different gases to MSc. students and new PhD students making e.g. use of the found ´flame´ characterization by means of the Borghi diagram (in D4.4). GWI: GWI published already results achieved in the frame of the BioPro project on the 6th HiTACG conference in Essen on 17th-19th Oct. 2005 and on the 7th European Conference on Industrial Furnaces and Boilers, Porto, Portugal, 18-21 April 2006. Furthermore, the following papers from BioPro project are planned for presentations and publications, respectively,
• An Efficient Combustion Concept for Low Calorific Gases.
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Paper is accepted for presentation on the „International Conference on Renewable Energy and Power Quality (ICREPQ ´07), Sevilla, Spain, 28-30 March 2007, This paper will be published in the conference proceedings.
• Development of a progressive combustion concept for low calorific gases from biomass gasification processes.
Paper is planned to be published in the magazine L'industrie céramique & verrière, Paris, France 2007
• New Burner Technology for Low Grade Biofuels. Paper is planned to be presented on the 23rd German Flame Day, 12./13. September 2007, TU Berlin, Germany. This paper will be published in the conference proceedings USTUTT: USTUTT provides a dedicated project server (www.eu-projects.de). On this server public a project web site (www.eu-projects.de/bio-pro) was set up and maintained. Several information for the public are published there. During the project period the website was used for data exchange between partners. Publications:
Journals: - R. Berger (USTUTT), M. Schmid (FATSE), J.G. Wünning; „Low-NOx lean-gas
combustion with flameless oxidation”; Gaswärme International, Vulkan-Verlag Essen, 2005
- R. Berger (USTUTT), A. Schuster (USTUTT), J.G. Wünning (WS): Neue Brennersysteme für Bio-Raffinerien; Gaswärme International, Vulkan-Verlag Essen, 2006
Conferences: - A. Schuster, J. Kieß, R. Berger (USTUTT): „FLOX-Brennertechnik für
Holzfeuerungen“. ALS-Holz-Kolloquium 2005, Stuttgart. - A. Schuster, R. Berger, G. Scheffknecht (USTUTT): „Utilisation of Solid Bio-
Residues in a New Combustion System Applying Flameless Oxidation”. 14th European Biomass Conference & Exhibition 2005, Paris/France.
- A. Schuster, R. Berger, G. Scheffknecht (USTUTT), J.G. Wünning (WS), M. Hiltunen, T. Eriksson (FW), M. Schmid, C. Gaegauf (FATSE): “New Burner technologies for low grade biofuels to supply clean energy for processes in biorefineries”. 14th European Biomass Conference & Exhibition 2005, Paris.
- A. Schuster, R. Berger, G. Scheffknecht (USTUTT), J.G. Wünning (WS), M. Hiltunen, T. Eriksson (FW): „Anwendung der flammlosen Oxidation zur Nutzung von schwierigen Biobrennstoffen - Entwicklung neuer Brenner für biomassestämmige Schwachgase“. Deutscher Flammentag 2005, Braunschweig.
- M. Schmid (FASTE), J.G. Wünning (WS), R. Berger (USTUTT): “New horizons for FLOX®-technology for biomass fuels”. 6th International Symposium on High Temperature Air Combustion and Gasification 2005, Essen.
- R. Berger (e-flox), T. Golec (IEN), A. Schuster (USTUTT): New burner systems for low calorific value gases integrated with pre-gasifiers. 10th International conference on boiler technology, Szczyrk, Orle Gniazdo, 17 – 20 October 2006
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- A. Schuster, M. Zieba, G. Scheffknecht (USTUTT), J.G. Wünning (WS): “Application of FLOX technology for the utilisation of low grade biofuels”. 15th European Biomass Conference & Exhibition 2007, Berlin/Germany.
- A. Schuster, M.Zieba, G. Scheffknecht (USTUTT), J.G. Wünning (WS):”Optimisation of conventional biomass combustion system by applying flameless oxidation”. 15th IFRF Member’s Conference, 2007, Pisa/Italy.
Consortium: Project results were presented in a workshop in February 2007. This workshop addressed interested parties from industry and science. Several parties declared their interest in the developed burner and in joint research activities for their further development. IFRF (International Flame and Research Foundation) declared their interest to publish the BIO-PRO workshop proceedings on their website.