Energy from Waste Gas & Reject Coal

Western States Coal Mine
Methane Recovery and Use
Western States Coal Mine Methane Recovery and Use Workshop
Workshop
Energy from Waste Gas & Reject
Coal
John G. Whellock Ph.D.
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Western States Coal Mine Methane Recovery and Use Workshop
CMM Recovery in USA
US EPA Underground CMM Source Data 2000
VAM
66%
27%
7%
Emissions avoided
Drained CMMavailable
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Potential Sources of Mine Gas
• Ventilation Air Methane (VAM) with 0-2% 0 2%
CH 4
• Low Quality Gas from less than 5% up to
27% CH 4, , which is too dangerous to flare
• Gob Gas or Coalmine Methane-CMM Methane CMM ~ 30- 30
90% CH 4—contaminated contaminated with O 2, , N 2 and
CO 2
• Flammability limits for methane 5-15% 5 15% CH 4
in air
Western States Coal Mine Methane Recovery and Use Workshop
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Issue in the Management of Mine
Western States Coal Mine Methane Recovery and Use Workshop
Methane
• Safety considerations are paramount
• Low quality gas is not flared but vented away from
operations
• VAM has insufficient fuel value to support combustion—
combustion
reluctance to burn the methane just to defray emission— emission
needs to make economic sense
• CMM, if contaminated with air or carbon dioxide, is
problematic for pipelining to market but technologies exist
for its upgrading
• Variability of the gas quality can create significant design
constraints
•
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Characteristics necessary for utilization
• Safe operation
of VAM as Ancillary Fuel
• Efficient use with low additional energy requirements
• Application of the recovered heat as power or alternative
energy
• Potential additional sources of heat with no virtual cost
• Combined use of coal mine rejects, VAM and/or low quality
gas provide new opportunities—application opportunities application of the TORBED*
Reactor-- Reactor--toroidal
toroidal fluidized bed reactor
*TORBED is the register registered ed trademark of of Mortimer Techn Techno olog logy y Holdings Holdings
Limited UK
Western States Coal Mine Methane Recovery and Use Workshop
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Considerations for Use of Low Quality
Methane approx. 2 to 30% CH 4
• Range below explosive limits i.e. VAM with ca.
0-2% 2% CH 4 can be used as combustion air source
feeding the reactor
• Explosive range is usually vented after being
drained
• Management of gas within the explosive limits
range—5-15% range 15% CH 4
• Above explosive range is usually vented or
flared
Western States Coal Mine Methane Recovery and Use Workshop
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The TORBED® Technology can be applied to
utilization of Low Quality CH 4 as Fuel
• The TORBED Expanded Bed Reactor can
be configured to burn low quality CH 4
(including that which is usually considered to
be within the explosive limits)
Western States Coal Mine Methane Recovery and Use Workshop
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TORBED process reactor technologies
The TORBED Compact Bed Reactor (CBR)
The process gas stream lifts a shallow compact bed
imparting horizontal motion and subjecting the
base layer of the bed to high impact gas velocities
and thus higher heat and mass transfer rates.
Western States Coal Mine Methane Recovery and Use Workshop
Torftech
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TORBED process reactor technologies
inner
vortex
bed bed
blades
Western States Coal Mine Methane Recovery and Use Workshop
The TORBED
Expanded Bed Reactor
(EBR)
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The process gas flow is increased until it
entrains all the bed particles in a rapidly
spinning inner vortex.
Particles separate by centrifugal force
from the inner vortex to the outer wall
before returning to the base of the reactor
creating a diffuse toroidal bed.
The base layer of the bed is subjected to
high impact gas velocities and thus high
heat and mass transfer rates.
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TORBED process reactor technologies
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The toroidal motion of the bed in this 300mm
diameter cold model is very clear
Western States Coal Mine Methane Recovery and Use Workshop
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TORBED process reactor technologies
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The passage of gas through the fixed blades produces a
diffuse bed with toroidal movement of the particles
Western States Coal Mine Methane Recovery and Use Workshop
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TORBED process reactor technologies
These EBRs are 6m in
internal diameter Expanded
Bed Reactors utilising
alumina to scrub HF emitted
from the smelting pots
Western States Coal Mine Methane Recovery and Use Workshop
The largest reactors are the
20 gas scrubbers installed in
two of the Comalco aluminium
smelters in New Zealand and
Tasmania.
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Coal Fines Problem or Opportunity?
• In the eastern USA alone, there are in excess of 2 billion
tons of coal fines, (EPRI ‘94), which might be reclaimed
• Use of coal fines is a function of properties—GCV, properties GCV, sulfur,
ash and size range for application
• Some is currently blended and utilized in PC fired boilers
• Some could be utilized in circulating fluid bed boilers
• Limits can sometimes be ash softening temperature, sulfur
level and ash management
• We see the opportunity for utilization of this material for:
• Co-processing Co processing with VAM or Low Quality Gas
• Steam or power raising at mine sites
• Drying of main production coal
• Fuel source for limestone calcination
• Devolatilization and char production
Western States Coal Mine Methane Recovery and Use Workshop
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Recent Testing of the TORBED
Western States Coal Mine Methane Recovery and Use Workshop
Technology in Poland
• TORBED Reactor used to devolatilize wet waste coal fines
(

Western States Coal Mine Methane Recovery and Use Workshop
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TORBED process reactor technologies
Combustion of Biomass is shown here
Western States Coal Mine Methane Recovery and Use Workshop
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Western States Coal Mine Methane Recovery and Use Workshop
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Western States Coal Mine Methane Recovery and Use Workshop
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Western States Coal Mine Methane Recovery and Use Workshop
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TORBED process reactor technologies
• Very high heat/mass transfer rates per unit volume-
superior to present technologies
• Particles—especially Particles especially fines-- fines--are
are processed efficiently due to
high centrifugal force
• Lower cost reactor with small footprint
• Low pressure drop operation compared with other high
efficiency solid-gas solid gas contactors enables reduced power for
high volumetric flowrates
Western States Coal Mine Methane Recovery and Use Workshop
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Special Characteristics of the TORBED Reactor
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TORBED Reactor used for Drying
Applications
• Low grade coal or rejects can be utilized in the
TORBED reactor for drying applications
• The reactor has low pressure drop and uses fuel
efficiently-- efficiently--therefore
therefore it can be applied as a
combustor for heating another drying process— process
e.g. rotary dryer
• For fine coals or pulverized fuel a second
TORBED can operate as a dryer. The design is
tolerant to solids
• The design has potential to remove inherent
moisture under careful atmosphere control
Western States Coal Mine Methane Recovery and Use Workshop
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TORBED Reactor used for Drying
Applications
FAN
HIGH GRADE
WET COAL
27% H 2 0
65 mtph
6.4% Ash
GCV 7800
Btu/lb
REJECT
COAL
FC 2 1%
VM 3 3%
H 2 O 23%
ASH 23%
3.8 mtph
AIR
2.5m. Dia
TORBED
DRYER
Western States Coal Mine Methane Recovery and Use Workshop
COAL PROCESSING FLOW DIAGRAM
650 o C
3.0m. Dia
TORBED
COMBUSTOR
110 o C
BAG
FILTER
FAN
41,400
Nm 3 /h
FAN STACK
DRIED PRODUCT
49.4 mtph
2.9% H 2 0, 10.4% Ash
GCV 10300 Btu/lb
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TORBED Reactor used for Char Production
and Power
• Coal fines used to partially fire TORBED Reactor
• Oxygen in reactor air is limited
• Volatiles burned to low level producing char
residual
• Cyclone off majority of char
• Complete combustion of fines and residual
volatiles in afterburner/boiler for power production
• Example shows 50 mtph of coal producing 35.8
mtph of char and steam for approx. 20MW of
power
Western States Coal Mine Methane Recovery and Use Workshop
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TORBED Reactor used for Char Production
and Power
INT. REF.#1015
AIR
COAL
FC 55.4%
VM 22.6 %
H 2 O 5.9%
ASH 16.1%
GCV 10580
Btu/lb
50,000 kg/h
@ 20 o C
116,178 kg/h
@ 20 o C
106,613 kg/h
GAS + 3975
kg/h CHAR
@ 650 o C
TORBED
T3500
650 o C
Western States Coal Mine Methane Recovery and Use Workshop
100 tph Steam
CYCLONE
TURBINE
AFTERBURNER BOILER
COAL
PROCESSING
FLOW DIAGRAM
FC 69 .7%
VM 10.0 %
ASH 20.3%
GCV 11170
Btu/lb
Condensate
150 o C
RECYCLE 96,363 kg/h @150 o C
(5% OXYGEN)
BAG FILTER
226,685
kg/h @ 150 o C
(5% OXYGEN)
FAN STACK
ASH 81 kg/h
CHAR 35,775 kg/h
EXHAUST
130,322 kg/h
@ 150 o C
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Assumptions-TORBED Assumptions TORBED Reactor Producing Char & Power
Power Generated
Coal Feed
Char Product
Cost of Power
Value of Char
Labor Cost
Cost of Coal Feed
Plant Depreciation
Maintenance Cost
Annual Operation
Capital Cost
Western States Coal Mine Methane Recovery and Use Workshop
MWh/h
tonnes/h
tonnes/h
$/MWh
$/tonne
$/h
$/tonne
%
% of TIC
hours
20
50
35.8
50
29
25
10
10
3
8000
$30 Million
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TORBED Reactor Pro Forma Economics
Power Sales—20 Sales 20 MWe
@ $50/MWh
Char Product Sales— Sales
286,400 tpa @ $29/t
Operating Costs
Net Estimated Revenue
Return on Investment
Western States Coal Mine Methane Recovery and Use Workshop
$ 8,000,000 per year
$ 8,305,600 per year
$ 8,900,000 per year
$ 7,405,600 per year
~25%
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TORBED Reactor used with VAM & Low
Quality Gas for Calcination of Lime
• VAM used as air supply
• Low quality gas injected into reactor above
blades
• Ground limestone processed at 800 oC • Coal fines may be used to compensate for
variability in low quality gas feed
• Example flowsheet follows..
Western States Coal Mine Methane Recovery and Use Workshop
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TORBED Reactor CMM and Lime
Calcination
WATER
CRUSHED
LIME
LOW
QUALITY
GAS
VAM
HEAT
EXCHANGER
OR WASTE
HEAT BOILER
TORBED
COMBUSTOR
Western States Coal Mine Methane Recovery and Use Workshop
LIME CALCINATION
PROCESS
FLOW DIAGRAM
STEAM TURBINE
BAG
FILTER
POWER FOR SALE
FAN STACK
POWDERED LIME FOR SALE
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TORBED Reactor can be used to burn
VAM in Combination with Low Quality CH 4
• An Example: Combust 8% CH 4, , using VAM (0.5%
CH 4) ) as combustion air/ lean fuel and circulate an
inert alumina bed (Al 2O3 )
• Alumina bed becomes a circulating heated mass
which helps maintain the temperature in the
reactor and diffuses the 8% CH 4 so that
combustion is stable (non-explosive)
(non explosive)
• All methane is consumed and resulting heat
energy can be used to generate electricity and run
a heat pump to cool mine intake air
Western States Coal Mine Methane Recovery and Use Workshop
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Example Low Quality CMM TORBED
Western States Coal Mine Methane Recovery and Use Workshop
Demo
• 3.5 m diameter TORBED Operating
temperature: 800 oC • VAM Feed to: 0.5% CH 4@ @ 18.6 m 3 /s
• CMM Feed to TORBED: 8%CH 4@ @ 10.0 m 3 /s
• Energy converted to Power = 5.70 MW
• Available for Chiller Circuit = 6.87 MW
• Total Power + Heat = 12.57 MW
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Low Quality CMM and VAM Utilization
LOW
QUALITY
GAS
10 am 3 /sec
8%CH 4
FAN
VAM 18.6
am 3 /sec
0.5% CH 4
Western States Coal Mine Methane Recovery and Use Workshop
Process Flow Diagram
800 O C
TORBED
REACTOR
BOILER
TURBO-
GENERATOR
INDUCTED
AIR
GROSS THERMAL INPUT
FROM METHANE 33 MW.
NET CO2 REDUCTION
337,000 TONNES/YEAR
~
5.7 MWe
HEAT
EXCHANGER
250 O C 70 O C
CHILLER
6.9 MW
FAN
FAN
SUFFICIENT FOR ~73
am 3/ sec AIR COOLED
FROM 90 % RH and 35 O C
TO 60 % RH and 18 O C
STACK
TO MINE
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Western States Coal Mine Methane Recovery and Use Workshop
Energy Converted
• Energy converted to Power = 5.70 MW
• Available for Chiller = 6.87 MW
• Can chill air from ambient of 35 oC C to 18o 18 C @ 50 m3 m /s
• Relative humidity is reduced from 100% to 90%
• Total Power + Heat = 12.57 MW
• (Ambient conditions make a difference in performance. For
example, if the total cooling duty is 4.5 MW, 3.5MW is used in
removing the humidity from the intake air, only 1 MW is used for fo
cooling the de-humidified de humidified air. Therefore, without high moisture
content, condensation heat load would be reduced and more
ventilation air could be cooled through the same temperature
range.)
• Cost for complete plant is estimated at $800,000 to
$1,000,000 per MW installed
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Emission Reduction
Credits Revenue
@ $5.00/t CO 2e Western States Coal Mine Methane Recovery and Use Workshop
Pro Forma Economics
Value of Power Displaced
@ $50/MWh
Value of Heating/Cooling
@ $5.00 GJ/h
Total Estimated Annual
Revenue
$1,506,426 per year
$2,495,752 per year
$1,082,978 per year
$5,085,156
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Western States Coal Mine Methane Recovery and Use Workshop
Conclusions
• Significant deposits of waste coal exist that could be
exploited. Waste gas in three low quality forms could
be utilized at coal mines
• To date a number of issues have inhibited the
successful exploitation of these resources at mine-
sites
• Technology is available that permits separate or co­- co
processing of these materials for generation of power
or for heating/cooling for mine applications
• The TORBED reactor enables efficient solids
processing & combustion of reject coal fines or
wastes. Flame dissipation can assure safe release of
the fuel value of low quality gas
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Western States Coal Mine Methane Recovery and Use Workshop
John G. Whellock Ph.D.
JohnW@JWTechnologies.com
(303) 773-2995 773 2995
Thank you
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