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Executive Summary

Study and development of biomass gasification unit

for agricultural pumping system

Proposed to

Department of Alternative Energy Development and Efficiency

(DEDE)

Ministry of Energy, thailand

By

Ubon Ratchathani University

July 2010

Executive summary

Study and development of biomass gasification unit for agricultural pumping system

Ubon Ratchathani University 1

Abstract

Biomass gas (sometimes called or producer gas or synthesis gas) is obtained from the thermal

reaction of biomass in the gasifier. The biomass gas can be often fed as fuel in the internal combustion

engine. It has been widely used in some countries, however, it is not quite developed and applied in

Thailand. This project studies and develops the biomass gasification unit for the agricultural pumping

system. The diesel engine was modified to be a neat gas engine and used as the power engine for the

pump. All of the equipment and machine used in this project was developed in Thailand and this will

encourage the promotion of biomass gasification in Thailand. This project was supported by the

Department of Alternative Energy Development and Efficiency (DEDE), Ministry of Energy, Thailand,

while the consulting and operating team was from Ubon Ratchathani University. The gasifier employed in

this project is the Downdraft Double throat with capacity of 320 kWth (or the gas flow rate of 240 Nm3/hr).

The biomass gas engine is the engine which is modified from the original diesel engine Mitsubishi

modeled 6D16. The engine was modified by reducing the compression ratio from 18:1 to 11:1, replacing

the fuel injector by the spark plug, and installing the ECU for controlling the ignition timing.

From the test, the biomass gas engine can operate properly at various engine speeds. After

connecting to the pump, the average pumping capacity of 1,000.72 m3/hr at engine speed of 1500 rpm can

be achieved. The overall efficiency of the whole system (from energy input to output hydraulic power) is

13.83% while the cost for pumping the water is 0.31 baht/m3. When this system is applied to the rice farm,

with pumping capacity of 10,000 /m3/day, it will be able to provide enough water for the rice farm of 734

rai (or 117.44 hectare). This generates the income of , , baht for the farmer while the energy cost,

compring to using electricity, of 167,700 can be saved. About the environmental impact, it is found that

there is only little amount of tar contaminated in the waste water and it is under the standard limit. The

raw material (biomass) management can be done by encouraging the people to grow the fast rotating tree

and selling to the community union or exchanging the biomass with the water. This will also produce the

income to the people and also save the expense that must be paid for the water.

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Content

Page

Abstract

Content

Executive summary

1. Survey and collect information about irrigation system, pumping system, and

biomass gasification technology.

2. Survey and site selection

3. Properties of the potential biomass and design the gasification system 0

4. Prepare and install the pilot biomass gasification plant and the pumping system 4

5. Test and Analysis of the Gasifier System 6

. Strategic plan to promote the use of biomass gasifier-pumping system 2

7. Seminar 3

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Executive summary

Water is considered as one of the most important thing for agriculture either for plant cultivation

or livestock farming. Presently, the farmer in Thailand mainly used the from the natural resource such as

river, canal, rainfall, or even underground water. However, for ones who are not living near the water

resource, the pumping and irrigation system are required. Currently, the pumps widely used in Thailand

are electrical or diesel engine pumps, because, it is friendly to buy, to operate, and to maintenance.

However, the energy cost for these pump are relative high. Therefore, it is important to research and

develop the renewable energy source as an alternative fuel for the pumping system.

Biomass gas (or producer gas) is one of the renewable fuel produced from the biomass by the

gasification process in the gasifier. The properly treated biomass gas can be used as fuel in the spark

ignition engine similar to LPG or CNG. From the preliminary survey, using the biomass gas replacing the

diesel or electricity in the large pumping system should be able to save energy cost. Therefore, the DEDE

has setup the project “study and development of the biomass gasification unit for the agricultural pumping

system” to investigate the feasibility of the project in aspects of biomas gas & engine technology,

operation, economics, management, and environmental impact. In this project, there are 7 major activities

as following

. Survey and collect information about irrigation system, pumping system, and biomass gasification

technology

2. Survey and select the most appropriate site to install the biomass gasification unit and the pumping

system

3. Analyze the properties of the potential biomass in the selected site and design the gasification system

4. Prepare and install the pilot biomass gasification plant and the pumping system

5. Test and analyze the whole system

6. Propose on the concept for promoting the system and prepare all related document.

7. Organize the seminar on the results of the study

Details of each major activities are as following.

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. Survey and collect information about irrigation system, pumping system, and biomass

gasification technology.

1.1 Survey and collect information about irrigation system

From the information survey, it is found that the irrigation systems which are available in

Thailand are mainly in the drought area but located beside the river or dam. There are many sizes of

irrigation system and driven by electric motor in all sites. These irrigation systems draw the water from

the river or dam. The smallest system and fit to this project is “pumping station by electricity” operated by

local authority as shown in Figure 1. It is usually served for a few villages and the pumping capacity is

around 1,000 m3/hr. Over the country, there should be around 2500 systems while about 1500 systems are

in the North Eastern region. Currently, only about 25% of them are still in operation, while the rest of

them are at rest, because the motor and the pump are old and need some maintenance. Some place did not

run the system due to the too high operation cost. However, almost of the irrigation systems are (cement

distribution canal) still in the good condition and possible to run with the proper pumping system.

Figure 1 Example of the living pumping station by electricity

1.2 Comparison of pumping system

The consultant has collected the information about the pumping system in order to review the

benefit and advantage of each system. The results are concluded in Table 1.

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Table 1 Comparison of power source for 1,000 m3/hr pumping capacity, at head of 17 m., and operating

for 10 hr/day

No. Detail Electric motor Diesel engine Natural Energy

(if possible)

Biomass gas

engine

Pumping stability Stable Depends on engine

speed

Not possible Depends on gas

supply and engine

performance

Maintenance

Low Medium/regularly - Medium/regularly

4 Operation Easy Need attention - Need high

attention

5 Initial cost 1 Million baht (not

including

distribution canal)

0.8 Million baht

( not including

distribution canal)

- 1.4 Million baht

( not including

distribution canal)

6 Power source kW 1 kW - 1 0 kW

7 Fuel consumption Electricity 110

kW-h /day

diesel 365.65

liter/day*

Wood chip 8

kg/day

8 Fuel cost/unit . baht/kW-h . baht/liter** - 1.0 baht/kg

9 Pumping cost per

day

, 0.00 baht 7,711.56 baht - 800. baht

Note* heating value of diesel equivalent to . kW-h/kg at density . kg/m3 at ºC and engine

thermal efficiency of %

** based on the retail price of PTT diesel on the 19th March 2009.

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1.3 Biomass gasification technology

Gasification is a process that converts carbonaceous materials, such as coal, petroleum, or

biomass, into carbon monoxide and hydrogen by reacting the raw material at high temperatures with a

controlled amount of oxygen. The resulting gas mixture is called synthesis gas or syngas (sometime called

producer gas, biomass gas, or wood gas). The synthesis gas itself is a fuel. Gasification is a very efficient

method for extracting energy from many different types of organic materials, and also has applications as

a clean waste disposal technique.

This process occurs in the limited oxygen condition; therefore carbon monoxide (CO) is the major

proportion in the producer gases. Other gases such as methane (CH4) and hydrogen (H2) also exist. During

the gasification process, there are series of reactions such as combustion, gasification or reduction,

pyrolysis, and drying which are separated in different zone in the gasifier as shown in Figure 2.

Producer Gas

Pyrolysis Zone

Combustion Zone

Gasification Zone

Drying Zone

Material

Unreacted carbon drop down with ash

Air

Figure 2 Gasification process in the downdraft gasifier

Types of Gasifier: the gasifier can be classified into 5 types according to the gasses flow

passages as followings.

1) Updraft Gasifier

2) Downdraft Gasifier

3) Cross draft Gasifier

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4) Fluidized bed Gasifier

5) Suspended Gasifier

From the literature and technology survey, it is found that the downdraft gasifier usually gives

quite clean gas and low in tar contamination. Also the firing process and the operation are quite simple

while the produced gas is constant. To use the biomass gas in the engine, other equipments such as dust

cyclone, cooling system, tar scrubber, fine filter, and blower are necessary

1.4 Biomass gas and spark ignition engine

The biomass gas can be used as fuel in the engine. However, to use it 100% in the engine, the

ignition system must be spark ignition (SI) only. The conceptual diagram of applying the biomass gas in

the SI engine is show in Figure 3. The compression ratio of the engine can be set at between 10.5:1 to 17:1

theoretically, while the ignition timing can be 20-25 degree before top dead center.

Figure 3 conceptual diagram of applying the biomass gas in the SI engine

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2. Survey and site selection

2.1 After the preliminary survey, the 10 most potential sites were selected and surveyed in

details. The site survey had been carried out and summarized in Table 2

Table 2 Information of 10 potential sites

No. Item

T

oong

koon

Oop

-moo

ng

Nav

ang

Koo

dkas

ean

Nok

ten

Pone

thon

g

Too

ng Y

ai

Sran

gkea

w

Vun

gkan

Tah

lard

Pump Installation raft raft raft raft raft shore shore shore shore shore

Static H (m)

3 Dynamic H (m)

4 Total H (m)

5 No. of main pipe

No. of pump

Watered area(Rai) , , , , , , , , , ,

Water variation level

(m)

Biomass fuel yes yes yes yes yes yes yes yes yes yes

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From the survey, the consultant has proposed 2 site as the most appropriate for this project. This

is based on the conditions; the water requirement is about 10,000 m3/day (operate the system for 10

hr/day), enough biomass in the site for 800 kg/day, and appropriate distribution canal. The example of the

criteria for the selection and marks of the most appropriate and selected site is shown in Table 3. The

selected site for this project is the Srangkeaw water pumping station in Piboon Mungsahan district, Ubon

Ratchathani.

Table 3 Criteria and mark of the selected site

Criteria

Mark

percentage

least low Medium-

low

medium high highest

1. installing location Pass/fail

2. water distribution system Pass/fail

. ownership right Pass/fail

. water demand 25

. water resource

. biomass fuel

. technical staff 15

. attitude of the leader

total

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3. Properties of the potential biomass and design the gasification system

. After the site has been selected, the biomass in the site area has been collected and tested

for their properties. Properties of 5 biomass sample are shown in Table 4. These properties are useful for

the design of the gasifier.

Table 4 Properties of biomass in the selected area

Proximate analysis Eucalyptus Rubber tree Black wattle

Horse

Tamarind Mixed wood

Moisture,% 5.6 6.4 6.4 5 5.9

Ash, % 0.98 2.4 0.65 1.6 1

Volatile Matter,% 78.7 73.3 76.4 76.8 75.4

Fixed Carbon, % 14.7 17.9 16.6 16.6 17.7

Ultimate analysis Eucalyptus Rubber tree Black wattle

Horse

Tamarind Mixed wood

Carbon, % 51.1 49.8 51.5 50.5 51.9

Hydrogen, % 6.6 6.3 7.1 6.5 6.5

Nitrogen, % 0.17 0.17 0.34 0.37 0.24

Sulfur, % 0.03 0.02 0.02 0.03 0.02

Oxygen, % 41.1 41.3 40.4 41 40.3

Other

characteristics Eucalyptus Rubber tree Black wattle

Horse

Tamarind Mixed wood

Gross Calorific

Value, cal/g 4,363 4,198 4,443 4,334 4,459

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3.2 The gasifier for producing biomass gas for the engine has been designed and built. It is

custom designed to fit with the conditions of the selected site and also with the pumping capacity of 1,000

m3/hr.

The design parameters can be summarized as following.

1. The suction pipe of the pump is 350.00 mm diameter

2. Rotating speed of the pump is 1,500 rpm

3. The discharge pipe of the pump is 350.00 mm diameter

4. Engine power is 120 HP (horse power) or 90 kW

At The engine power of 90 kW, with thermal efficiency of the engine 28%, the thermal power

supply from the gasifier is 320 kW, therefore this becomes the conditions for the gasifier design.

Principle and design concept

The Inbert type gasifer which is based on the Swedish design is used. The gasifier is a Double

Throat Downdraft Gasifier

Major parameters calculation

Type: Imbert Type (with heart constriction ring)

Design Condition: Heating value of biomass gases 4,800.00 kJ/m3

Thermal power output 0.00 kWth

Safety factor (Oversize) . kWth

Maximum thermal power output . kWth

Biomass consumption

Thermal power output 0 kWth

Thermal efficiency of the biomass gasification 70 percent

i.e. biomass consumption ( at Full load) . kWth

Heating value of corn cob (at moisture content %) 11,000.00 kJ/kg

or 1 kg/h

Biomass gases flow rate 240 m3/h

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Figure 4 Dimension of combustion and gasification zone

Gasifer dimension

The most important dimensions of the gasifer which is the combustion and gasification zone shown in

Figure 4. Figure 5 shows the overview, structure, and components of the biomass gasifier.

190 mm

410 mm

16 mm/7 nozzle

135mm

153 mm

370 mm

315.5m

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Figure 5 Overview and structure of biomass gasifier

biomass feeding hopper

Holding

structure

Biomass stock tank

Combustion and gasification zone

Cyclone (dust separator)

Blower

Tested burner

Output gases Control box

Ash draining port

Gas cooling unit

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4. Prepare and install the pilot biomass gasification plant and the pumping system

. pilot biomass gasification plant

After the designed gasifier had been approved by the DEDE, the gasifier has been built

and preliminary test at the workshop as shown in Figure 6.

Figure 6 Pilot gasifier unit ready for the test

. Pumping system including biomass gas engine

Figure 7 describes the biomass gas engine and suction pimpe of the pump. The pump

used in this project is the mixed flow pump which installs on the shore beside the river. The engine was

modified from the original diesel engine to be biomass gas engine. The detail of the modification is listed

in Table 5.

Figure 7 Biomass gas engine and suction pipe of the pump

Executive summary



Table 5 List of engine modification

No. Item Detail Reason

Compression

ratio

Compression ration was reduced from

18:1 to be 11:1 by using shim plate to

increase the cylinder head volume.

- Original compression ration was

18:1 and suitable for diesel fuel. For

biomass gas and SI engine, it should

be around 11:1 to avoid knocking.

Ignition system The spark plug was installed by

replacing the injector. The sensor to

detect the crank angle was installed

and works with the ECU. The ignition

timing can be set at 20-25 degree

before top dead center.

- The SI engine principle must be

used for the biomass gas fuel.

Air-fuel mixer The air-fuel mixer (similar to

carburetor in typical gas engine) has

been installed. This air-fuel mixer set

can operate with biomass gas and also

LPG.

- The original was only an air intake

port.

Engine cooling

system

- change from blow through to be

draw through fan and add one more

radiator.

- For stationary engine, it needs

higher the cooling capacity, the draw

through fan is more suitable.

. Installation of pilot plant at the selected site

After all the facilities have been preliminary tests, they were transferred to the selected

site and install in the plant. The plant was designed and built to fit with all equipment as shown in Figure

8.

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Figure 8 The gasifier installation in the pilot plant.

5. Test and Analysis of the Gasifier System

. System Testing

After obtaining good performance of the system for the first few hours-test run, the testing time of

totally 130 hours was conducted and divided into 2 testing periods. The 1st period was a 30 hours

preliminary test of the system prior to a data collection test. The 1st period of the test showed that the

system can be operated continually, only minor improvements were needed. The 2nd period was a 100

hours operation testing, as shown in figure , for collecting all data necessitated to the performance

analysis. Results obtained from the 2nd period testing were illustrated in Table 6 and 7.

Temperature measurement results of various points in the system are shown in Table 6. Table 7

shows the properties of producer gas obtained from the current gasifier system.

Figure The 2nd period testing of the system

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Table Temperature measurement results of various points in the system

Location of Measurement Temperature (°C)

1 Combustion Zone 1,150 – 1,400

2 Outlet of Gasifier 350 – 430

3 Outlet of Gas cooler 45 – 50

4 Inlet of the modified gas engine 40 – 50

5 Ambient temperature 30 – 42

Table Properties of producer gas obtained from the current woodchips-gasifier system.

No. Gas compositions % of volumetric concentration

(% v/v)

1 H2 7.2362

2 CH4 5.6448

3 CO 19.5324

4 O2 7.9742

5 CO2 9.0043

6 N2 50.6081

Total 100

Relationships of Biomass Fuel Consumption and Pumping Capacity

From the test, it is shown that the average flow rate of pumping water obtained from the system

is 1,000.72 m3/hr at an average engine speed of 1,500.18 rpm. At this pumping capacity, the system

consumes 82.2 kg/hr of woodchip with its overall efficiency of 13.83 %.

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. System Analysis

After the test was completed, all acquired data had been analysed. The system’s

performance analysis and the economics analysis were performed. The analysis results were as shown in

the following section.

Calculated Efficiency of various parts

Gasifier’s Thermal Effieciency . %

Gas Engine and Pump’s Efficiency . %

Overall System’s Efficiency . %

From the calculation of the measurement results, efficiency of the system can be illustrated as

shown in Figure .

Figure Combined efficiency of gasifier and water pumping system

70.49%

Gasifier

19.62%

Water pumping system

Overall efficiency = 13.83 %

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5.3 Economics Analysis

This economic analysis is based on the system operation of 10 hours/day. The lifetime of 10 years

is reasonably assumed. The calculated energy costs for the systems operation (bath per cubic meters of

pumping water) of the current system compare to other systems are shown in Figure 1 .

0.3

1.11

0 00.083

0

0.2

0.4

0.6

0.8

1

1.2

Ene

rgy

Cos

t (ba

th/m

3 )

Electrical pumping system

Deisel engine-pumping system

Wind energy-pumping system

Solar energy-pumping system

Gasifier-pumping system

Figure Energy operated cost of various water pumping systems

From figure 10, it is obvious that the highest energy cost of 1.11 bath/m3 is from the pumping

system using diesel engine. While using the electrical pumping system, the energy cost is about 0.3

bath/m3. The current system provides the energy cost of 0.083 bath/m3. There are no energy cost for the

systems using solar and wind energy. However, if the investment cost and energy operated cost are

combined for a 10 yrs lifetime as shown in Figure 1 , the system using solar energy produced the highest

cost. Whereas, the system with biomass gasification system produced the lowest cost of 0.31 bath/m3.

0.55

1.27

0.65

2.65

0.31

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Ener

gy c

ost (

bath

/m3 )

Electrical pumping system

Diesel engine-pumping system

Wind energy-pumping system

Solar energy-pumping system

Gasifier-pumping system

Figure Investment cost combined with energy operated cost of various water pumping

systems

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5.4 Environmental Impacts

From the test at the installation plant, it was also found that there was small pollution from the

system. The environmental impacts and their sources and proposed solutions are concluded in Table 8.

.

Table Environmental impacts’ evaluation and their solutions

Item Pollution Sources Impacts Solutions

1 Exhaust

gas

From engine exhaust duct and

from suction blower.

Emission of CO and

CO2.

Tree planting around

the installation plant.

2 Tar From filtering system Polluted water from

filtering system.

Waste water treatment

3 Dust From solid biomass preparation Low amount of dust from

cutting and chopping

woods or other solid fuel.

Regular Cleaning

4 Noise From modified gas engine Low impact with less

than 90dB. The noise

source is at a far distance

from households.

No need

5 Heat From the gasifier stove’s wall

and from the tested burner.

Low impact. -

6 Forest

destruction

From wood cutting. Low impact since small

pieces of wood or

woodchip can be used as

fuel.

Plating fast growing

forest to use as fuel

instead of using woods

from natural forest.

From Table 8, it can be seen that this system produces very low environmental impact. Since this

small gasifier-pumping system causes low pollution.

5.5 Problems and Obstacles

Throughout the project, there are some problems and obstacles that can be classified into 2 types;

technical problems and general problems.

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5.5.1 Technical Problems

Since this gasifier-pumping system is a prototype system, its design and construction was all

original. Thus, there were some technical problems when this prototype system was truly operated.

Moreover, there were some technical problems caused by physical limitations of the installation site.

These physical limitations affect the system’s performance and its operational characteristics. The

following topics are such technical problems and their suggested solutions.

1. Time limitation:

The duration time of the project was too short. Generally, research and development of

prototype machinery requires al least 3 years to develop and identify problems and disadvantages in

the long run of the system. So that the system can be improved, and subsequently, can be really

applied for use with no defects.

2. Physical limitation:

There is a physical problem of the plant’s location. The gasifier stove could not be constructed at a

closed distance to the gas engine. Therefore, the actual pressure drop across the system is higher than

it was designed. Moreover, there are damage and corrosion of the existing irrigation piping system.

The corrosion causes the higher friction pressure loss in the piping system than that obtained from

calculation. Since, in the calculation, all piping system and its equipment were assumed to be in good

condition.

5.5.2 General Problems

1. Lack of motivation of expenditure due to the fact that biomass fuel (woodchips) cost of the

gasifier pumping system is currently increased. While only 50 percent of total electricity costs (3

bath/kWh) were charged to the local farmers as subsidization when using the electrical pumping

system.

. The system is complicated and is unfamiliar for the operation of local staff.

The investment cost of the current gasifier-pumping system is relatively high for local farmers. If

such the system is to be widely promoted, the smaller size, and thus, the lower cost of the system

would be more attractive.

3. There are some management problems of the local government agency whom the electrical

pumping station’s responsibility was recently transferred from Ministry of Agriculture and

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Cooperatives. To maximize the farmers’ benefit, it is suggested that the management of pumping

station need to be restructured.

6. Strategic plan to promote the use of biomass gasifier-pumping system.

. To promote the use of biomass gasifier-pumping system, a 10 years strategic plan was

proposed. This strategy was set under the Energy Strategy On Renewable Energy item 2.3, 2.4 and 2.5

issued by the Bureau of Policy and Strategy, Office of Permanent Secretary, Ministry of Energy

(announced on 30 DEC 2008).

The 10 years strategic plan is divided into 2 phases. The first 5 year of the plan focuses on

supporting research and development of the technology and also enhancing strong expertise research

networks. Moreover, in the first phase, public’s education of the technology is to be promoted. The second

phase focuses on promotion of the system’s production in commercial scale and widely distribution the

use of such system.

. Operation and maintenance manual

All important information of the system including the equipment and instrument’s detail,

operation method, problems and solutions, and precautions were published in an “Operation and

maintenance manual for a gasifier pumping system” as shown in Figure1 . In this manual, the detailed

drawing of the system is also attached.

Figure 3 Operation and maintenance manual for the gasifier-pumping system.

Executive summary



7. Seminar

The seminar was conducted on July 9, 2010. The seminar was held at Kang Sapeau-River Side

Hotel, Piboolmangsaharn District, Ubon Ratchathani. There were 139 participants in the seminar

including 48 participants from the local government agency, 35 participants from general public, 42

participants from others government agencies and 14 participants from the Department of Alternative

Energy Development and Energy Conservation and Ubon Ratchathani University. The objectives of the

seminar were to disseminate results of the study and also to promote the use of biomass gasification

technology.

The seminar was divided into the 2 sessions. In the morning session, a basic lecture on biomass

gasification, a gasifier’s exhibition and the design information of the prototype system were provided as

shown in Figure14 and Figure15. In the afternoon session, there was an observation & demonstration trip

to the installation site (Figure 16), the place where the prototype system is installed.

Figure 4 The gasifier exhibition

Figure 5 Lecture session of the seminar

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Figure 6 A trip to observe the prototype gasifier-pumping system

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