Susnata SamantaAugust 2016
Activated Carbon in Biomethane Production
Pedro Paixão
August 24th 2017
RCGI/GBIO/IEE
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Agenda
Activated Carbon, Adsorption Process, Generalities
Activated Carbon for Biogas Purification
Activated Carbon Performance Data
23 AUGUST 2017 / PRESENTATION TITLE / CONFIDENTIAL / NOT FOR REDISTRIBUTION 3
Cabot-Norit Activated Carbon,Adsorption Process& Generalities
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Global Asset Base to Serve Customers
• 43 manufacturing sites in 21 countries, all with local management teams• 23 sales locations in 17 countries
manufacturing sitessales locationsaffiliatesregional headquarters
35%
30%
35%
AsiaAmericas
EMEA
Revenues
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Activated Carbon and Adsorption
Micropores < 1 nmMesopores 1-25 nmMacropores > 25 nm
Van der Waals forces allow the “capture” of impurities at the activated
carbon pores’ surface
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Raw Materials
Anthracite Coal
Bituminous Coal
Sub-Bituminous Coal
Lignite Coal
Coconut Shell
Peat
Wood
Olive Stones
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Production: Activation Processes
Process Goal Produce materials with extremely high internal porosity
and surface area, thus optimized adsorption efficiency and capacity, maintaining a consistent physical structure.
Specific finshing processes to enhance certain activated carbon characteristics, depending on the final application (e.g. washing, impregnation, pH adjustment, milling,...).
Cabot has the best manufacturing technology in place for the production of activated carbon, as well as access to a wide range of raw materials
Types of Activation Chemical Activation
Steam Activation
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Activated Carbon for Biogas Purification
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Biogas: Activated Carbon Application Data
Source Biogas
Application
Agriculture
Waste
(animal or
vegetal)
Landfills
Engine or Microturbine
Fuel Cell
Gas Grid
WWTP’s
Biogas is a mixture of methane, CO2, moisture and traces of other contaminants. Biogas is widely available, renewable and
a sustainable energy source with an undisturbed supply of power. Biogas can be produced of a wide variety of available
organic materials like agriculture waste, crop residues, animal manure, sewage sludge and municipal organic waste. Biogas
is produced to generate electricity, heat or it could be upgraded to pipeline quality and connected to the national gas grid.
Electricity Production
Challenge Comment AC potential
Siloxanes Present
H2SPresent; Oxygen + moisture required, H2S concentration ideal max 200ppm, competitive technologies
Market Well documented
Siloxanes Present
H2SPresent; Oxygen + moisture required H2S concentration ideal max 200ppm,Competitive technologies
Market Well documented
Siloxanes Not present
H2SPresent; H2S concentration too high, competitive technologies
Market Fragmented, small volumes
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Energy Production: Engines, Microturbines
Removal of Siloxanes and/or H2S
Biogas Upgrade to Biomethane for Gas Grid or Fuel Cell
Removal of Siloxanes and/or H2S and/or VOC’s
Siloxanes removal to avoid fouling, which negatively impacts equipment life-time andoperation downtime. Siloxanes are literally the sand in the equipment!
Hydrogen Sulfide (H2S) removal to avoid heavy corrosion problems in the biogasprocessing equipment. H2S is a dangerous acidic gas, harmful to the environment.
Main Activated Carbon Applications
PSA / TSA (Pressure / Temperature Swing Adsorption) both technologies may workwith a carbon bed, or may use an activated carbon polishing filter (mainly for siloxanesand/or VOC’s, and perhaps some H2S traces if necessary).
Scrubbers are used to separate CO2, H2S and other contaminants from biogas, and canbe followed by activated carbon for final polishing (mainly siloxanes / VOC’s removal).
Membranes for CO2 removal, normally downstream an activated carbon filter that hasto effectively remove Siloxanes and VOC’s.
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Biogas Purification Process
Raw Biogas:
~ 60% Methane
~ 38 % CO2
~ 0-2% Oxygen
~ 1-500 ppm H2S
~ 1-10 ppm Siloxanes
~ 1-500 ppm VOCs
~ 5-20% Humidity
H2S Removal
GAC vessel
Chemical Rx. on AC surface, presence of oxygen & moisture
Physical Ads. from dry gas on AC surface
GAC vessel
Siloxane RemovalDrying to remove
moisture
Raw Biogas:
~ 60% Methane
~ 38 % CO2
~ 0-2% Oxygen
~ 1-5,000 ppm H2S
~ 1-10 ppm Siloxanes
~ 1-500 ppm VOCs
~ 90-100% Humidity
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Why is Removal of Siloxanes, H2S, VOC’s Critical?
➢ Increases maintenance costs
➢ Reduces amount of gas processed
➢ Reduces lifetime of equipment
➢ Regulations (pipelines / environmental)
Source
Removal of Siloxanes and H2S Significantly Reduces Operational Costs
Spark Plugs
source
Boiler Tubes
Biogas:
~ 60% Methane
~ 38 % CO2
~ 0-2% Oxygen
~ 1-500 ppm H2S
~ 1-10 ppm Siloxanes
~ 1-500 ppm VOCs
~ 5-20% RH
COMPLIANCE!
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Cabot-Norit Activated Carbon Product Portfolio for Biogas Purification
Raw Gas Composition
SiOx Species and concentration?
Grade Main Function
Darco BG1Efficient in the removal of H2S and some siloxanes –better on the purification of relatively low gas streams.
Darco BGH
Multiuse grade for H2S adsorption (and also some siloxanes in certain operational conditions). Highcapacity for H2S (reduced carbon bed change-out frequency) and VOC’s.
Norit RST
Pelletized grade, not impregnated, with catalytic properties and low pressure drop. Still needs presence of O2 and moisture for effective H2S adsorption. Efficient adsorption of VOC’s.
Norit RGM
Pelletized grade, impregnated, allowing H2S oxidation and transformation in elemental sulfur, thus efficient adsorption in the presence of low O2
concentrations in the gas.
Norit RB / Norit RBW
Cost-effective pelletized grades with low pressure drop. Standard line of carbons designed for effective removal of a wide range of SiOx’s and VOC’s.
Norit SILPURE
Premium pelletized carbon, designed for preferential removal of siloxanes (lower affinity for VOCs – allowing lower carbon change-out frequency and optimized operational costs).
VOC Species and concentration?
H2S, O2, Relative Humidity?
Flow? T? P? Treatment Process?
Desired Gas Specs After the Carbon?
Final Biogas Application? Engines?
Upgrade to biomethane? Other?
23 AUGUST 2017 / PRESENTATION TITLE / CONFIDENTIAL / NOT FOR REDISTRIBUTION 14
Activated Carbon Performance Data
Lab, Pilot and Industrial Trials
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Siloxanes Removal
Pore Size Distribution
Raw material Mineral / Veget.
Activation method
Steam / Chemical
Long Service Life / Less
Change Out
Pore Volume, Surface Area
Surface chemistry of AC
Preferential Adsorption
Fate of Spent Carbon
Non-Hazardous Waste
Heavy Metals in AC
Heavy Metals in Biogas
Easy Change Out
No Surface Reaction
Pressure Drop
Granular/
Extruded
Carbon
Toolbox for Enhanced Siloxanes Removal
Technical Capability – Gaps
• Collaborative Work with Universities and External Labs
No in House Capability to Measure Siloxane Adsorption
• Customer Trials – Field Validation
Biogas is a Complex Mixture to Mimic in Lab
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INLET
INLET
OUTLET
OUTLET
Preferential Desorption of VOCs!
Standard Carbon for Siloxanes and VOCs
Silpure
VOCs
Siloxanes
Hypothesis: Schematic for Preferential Affinity
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D4/Toluene Mixed Stream DataSTANDARD ACTIVATED CARBON #1
STANDARD ACTIVATED CARBON #2
Silpure
Silpure preferentially desorbs VOCs in the presence of D4
Impurity Conc.:
620-660 ppm D4
470-530 ppm Toluene
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Impurity Conc.:
403-453 ppm L2
452-499 ppm Toluene
L2/Toluene Mixed Stream Data
Silpure preferentially desorb VOCs in presence of L2
STANDARD ACTIVATED CARBON #1
STANDARD ACTIVATED CARBON #2
Silpure
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Silpure
Standard Activated Carbon #2
Different types of activated carbon show different breakthrough nature
Lets make Biogas in lab
Very high ppm level of impurities
Ratio based on typical Spanish landfill gas composition
Absolute concentration chosen to manipulate test time
Gas Composition:
L2: 70 ppm
Toluene : 1300 ppm
D4 : 630 ppm
Limonene: 200 ppm
D5: 650 ppm
Multi-stream Data: L2/D4/D5/Toluene/Limonene
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1• Silpure has a higher affinity for siloxanes
2• With Silpure, toluene preferentially desorbs in the
presence of siloxanes
3• Gas streams with numerous compounds are difficult to
model
Key Learning form Spanish Lab Data
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Industrial Trial 1 – USA Landfill
• Southern Landfill, DE (June 2016)
• Poor performance of traditional AC
• Hypothesis: high concentration of H2S/VOC saturated AC
• Raw gas has 500 ppm of H2S, 45 ppm of VOCs and 4 ppm siloxanes (95% TMS)
• Cabot proposed 2 carbon grades
Silpure 1584 lbs / Standard Carbon: 2381 lbs
• 1 Vessel in each bank filled with each product
• Flow 1300 SCFM (650 SCFM Splits in 2 banks)
• Gas sample collected everyday (inlet and 2 outlets)
• Gas samples analyzed to monitor carbon performance at the Centek Lab
Sample Collection
port
Inlet Gas
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Impurities Removal Summary
Silpure Standard Cabot-Norit Carbon
# of Vessels 1 3
# of pounds (total) 1584 2381
RawGas
Adsorbed % NOTAdsorbed
RawGas
Adsorbed % NotAdsorbed
Siloxanes (lbs) 15 15 0 10 8.9 11
VOCs (lbs) 116 40 66 87 62 30
H2S (lbs) 465 307 34 305 170 44
Total gas processed (MSCF)
14.1 9.4
# of days 15 10
Silpure captured 30% more siloxanes than Standard Carbon
Silpure desorbed 35% more VOC’s compared to Standard Carbon
1584 lbs Silpure processed 33% more gas compared to 2381 lbs of Standard Carbon
In comparison at equal weight, Silpure performs 50% better
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Performance Summary
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Industrial Trial 2 – UK Landfill
Norit® Silpure Competitive Carbon
# of Vessels 1 3
# of kgs 720 3000
RawGas
Adsorbed % Adsorbed RawGas
Adsorbed % Adsorbed
Siloxanes (kgs) 5.8 3.0 52 5.8 0.8 12
H2S (kgs) 123 112 91 123 25 22
Total gas processed (MM M3/27 days)
3.2 3.2 (Not considering downtime)
# of days 27 27
On an equal weight basis, Norit® Silpure removes 15x more siloxanes
UK landfill site: 5 engines operating in parallel
Gas contains siloxanes, VOC’s and ~350ppm of H2S
Flow rate ~500m3/hr per engine
Incumbent: 4 mm reactivated AC, 1000kg each vessel
Trial: One Norit Slpure Vessel with 720kg of AC
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Performance Summary
➢ Customer’s Target limit 10mg/m3 of Silicon from Siloxanes
➢ Competitive AC vessels kept exceeding the 10mg/m3 Si target
0
5
10
15
20
25
0 1 2 3 4 5 6 7
Silic
on
(Si
) m
g/m
3
Competitive AC Exchange Dates
Comp. AC 2-day4
Competitive AC 1-day 8
Comp. AC-day3
Competitive AC 3-day 10
Cabot 1-day 8
Cabot 1-day 12 Cabot 1-day 21
Cabot 1-day 27
Competitive AC 2 -day 9Estimates breakthrough time
30th May 7th June 16th June 26th June
Competitive AC
Cabot
Norit®Silpure lasted 15x more than competitive AC during trial period
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Norit Siloxane Index
The Norit Siloxane Index (NSI) is a measured value highly correlated to siloxane removal performance.
The NSI is a numerical outcome measuring the siloxanes’ adsorption capacity of a media under real life conditions.
NORIT® SILPURE activated carbon has an NSI of 100, higher than traditional coconut / bituminous carbons. In the same biogas stream NORIT SILPURE will remove 55% more siloxanes by weight vs. coconut and 50% more than coal based carbons.
100
45 50
0
20
40
60
80
100
120
Silpure Coconut Coal
No
rit
Silo
xan
e In
dex
NSI comparison for Silpure vs traditional activated carbon
Silpure
Coconut
Coal
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Benefits of the Novel Grade Norit Silpure
Optimized performance in the removal of all SiOx species,
including the most difficult ones such as L2 and TMS.
Surface chemistry allows preferential desorption of high
calorific power VOC’s, while all the SiOx’s are retained.
Reduced plant downtime, maximization of biogas/biomethane production.
Significantly lower CAPEX than alternative technologies for siloxanes removal.
Optimization of plants with limited gas flow available: Silpure shows long lifetime
(low bed change-out frequency / low OPEX), allowing continuous operation without
the use of valuable gas for vessel media regeneration.
Operational and maintenance costs optimization: reduction of engine cleansings in
70%, lub oil changes in 50%, and emission control (catalysts) in 50%.
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Industrial Trial 3 – H2S Removal from Landfill Gas
DARCO BGH DARCO BG1 Iron Oxide Media
Media Mass lbs. 58,500 73,125 195,000
Total Media Cost $102,375 $95,063 $146,250
Total Media Change Out Days 3.25 3.78 11.7
Total Change Out Cost $22,100 $25,720 $79,560
Total Customer Cost $124,475 $120,782 $225,810
Cost per lb. of H2S removed $5.32 $5.16 $9.65
Total customer savings $101,335 $105,028
Fewer Days of Downtime 8.45 7.92
Annual Customer Cost Comparison
Landfill • Have developed or constructed more
than 50 projects over the last 25 years • Currently owns 29 projects that generate
electricity, six that produce pipeline-quality gas, and provides operational and maintenance services to nine projects owned by third parties
• Estimated that gas generation will total more than 905 million MMBtu over the next 20 years.
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Performance Summary
Test intended to mimic real life field conditions
Darco BG1 is a non-impregnated catalytic carbon
Darco BG1 has 2x the life of impregnated competitors
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H2S Removal Performance
4.33.8
4.7
6.6
0.51.2
0.50.50.5
6.3
Potassium AC
Iron Oxide Media
Caustic AC
5.2
DARCO BG1
4.3
Darco BGH
4.7
7.17.4
O&M
Media
19%
32%
DARCO BGH
50%
23%
DARCO BG1
Potassium AC
Caustic AC Iron Oxide Media
12%
Competition
Cabot
H2S Loading Capacity % $ per lb. of H2S Removed
Muito Obrigado!
Tecnical Contact:
Pedro PaixãoApplications Mgr. – South America
Tel (11) [email protected]
Commercial Contact:
Adriana RussiRegional Business Mgr.
Tel (11) [email protected]