chemical looping combustion reference plant...
TRANSCRIPT
National Energy Technology Laboratory
Driving Innovation ♦ Delivering Results
Robert Stevens, Ph.D.
US Dept. of Energy – NETL
September 1, 2015
CHEMICAL LOOPING COMBUSTION
REFERENCE PLANT DESIGNS AND
SENSITIVITY STUDIES
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Chemical Looping Combustion Basics
Reducer Oxidizer
Fuel:Coal
Natural Gas
Make-up Carrier
Heat
Recovery
Me
MeO
AirSteam
Ash
O2-depleted AirCO2 & H2O
Reducer:CHX + MeO → CO2 + H2O + Me
Oxidizer:Me + O2 MeO
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Objectives
• Develop Reference coal-based CLC power plant reactor models and process simulations
− Fe2O3 oxygen-carrier
− CaSO4 oxygen-carrier
• Estimate power plant performance and cost
• Estimate power plant component performance and cost sensitivities to key design parameters
• Guide research and development
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Design Basis – Chemical Looping Combustion
• Generic Midwest US site
• ISO conditions
• Coal: Illinois #6
• Steam conditions: 3500 psig/1100 °F/1100 °F
• At least 90% carbon capture
• CO2 product purity at least 95 mol%
• CO2 product delivery pressure: 2200 psig
• Major equipment performance and cost assumptions consistent with the NETL Bituminous Baseline report
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CFB CLC Plant Block Flow Diagram
Source: NETL
Recovered fuel to oxidizer
Oxidized ReducedFe2O3 Fe3O4
CaSO4 CaS
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CLC Reference Plant Overall Performance and Cost Results
Oxygen-carrier type Fe2O3 CaSO4
SCPC with capture (1)
Plant Capacity (MW) 550 550 550
Plant Efficiency (%, HHV) 35.1 32.6 28.4
Carbon Capture Efficiency (%) 95.8 91.4 90
CO2 Product Purity (mole% CO2/ ppmv O2)
98.9 / 7 (w/o purification)
99.7 / 0(w/ purification)
100 / 0
Total Plant Cost ($/kW) 2,379 2,597 3,563 (2)
O&M ($/MWh) 25.7 8.4 13.2 (2)
Cost of Electricity ($/MWh)w/o T&S
115.2 104.7 137.3 (2)
Reduction in COE (%)[Reference IGCC w/ CCS]
13.4% 21.3% ~0%
1. DOE/NETL-2010/1397, ”Cost and Performance Baseline for Fossil Energy Plants Volume 1: Bituminous Coal and Natural Gas to Electricity”, Rev. 2 (Nov. 2010)
2. DOE/NETL-341/082312, “Updated Costs (June 2011 Basis) for Selected Bituminous Baseline Cases” (Aug. 2012)
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Reference Plant Cost Breakdown (2011$/kW)
Fe2O3 CaSO4 SCPC w/ Cap
CLC System (or Boiler & CO2 sys) 729 785 795 + 920
Reactors, Cyclones, and piping 87 102 n/a
Char/O2-Carrier & Ash Separator 0 0 n/a
HRSGs 326 351 n/a
CLC BoP (w FD and ID fans) 315 331 n/a
Gas Cleanup 161 229 357
CO2 Purification& Compression 159 202 159
BOP 1,330 1,381 1,332
Total Plant Cost 2,379 2,597 3,563
• The primary reactor costs have small impact on the total plant cost• They must have “feasible” designs with high performance and reliability
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Reference Plant COE Breakdown (2011$)
Fe2O3
($/MWh)CaSO4
($/MWh)SCPC w/ Cap
($/MWh)
Capital 49.6 53.4 73.1
Fixed 11.3 12.2 15.7
Variable 25.7 8.4 13.2
Maintenance materials 3.2 3.5 4.7
Water 0.4 0.4 0.9
O2-Carrier makeup 18.7 1.1 0.4 (solvent)
Other chemicals & catalyst 1.9 1.7 5.7
Waste disposal 1.4 1.7 1.3
Fuel 28.6 30.8 35.3
Total 115.2 104.7 137.3
Fe2O3 oxygen-carrier makeup: 132 tons/day @ $2,000 per tonLimestone O2-carrier makeup: 439 tons/day @ $33.5 per ton
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Reducer Sensitivity Parameters
Oxygen-Carrier Type Fe2O3 CaSO4
Reference Plant Fixed Parameters
Steam feed rate (moles/mole C) 0.44 0.44
Recycle-CO2 feed rate (moles/mole C) 0.031 0.031
Oxygen-carrier inlet extent of conversionFe2O3 to Fe3O4 or CaSO4 to CaS
0.069 0.0
Cyclone recycle ratio 4:1 4:1
Sensitivity Parameters & Reference Plant Values
Oxygen-carrier outlet extent of conversion 0.687 0.177
Reducer temperature (°F) 1745 1800
Reducer outlet gas velocity (ft/s) 30 29
Reducer overall carbon conversion with or without char separation and recycle (%)
96 96
Sensitivity Characteristics & Reference Plant Values
Reducer vessel height (ft) 115 87
Reducer vessel shell ID (ft) 39 41
Reducer pressure drop (psi) 21.4 2.9
Reducer off-gas H2 & CO (mole%) 0.05 1.5
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Oxidizer Sensitivity Parameters
Oxygen-Carrier Type Fe2O3 CaSO4
Reference Plant Fixed Parameters
Off-gas oxygen content (mole%) 3.5 3.5
Oxygen-carrier inlet extent of conversion 0.313 0.823
Cyclone recycle ratio 3:1 3:1
Sensitivity Parameters & Reference Plant Values
Oxygen-carrier outlet extent of conversionFe3O4 to Fe2O3 or CaS to CaSO4
0.931 1.0
Oxidizer temperature (°F) 1800 2000
Oxidizer inlet gas velocity (ft/s) 32 30
Sensitivity Characteristics & Reference Plant Values
Oxidizer vessel height (ft) 39 54
Oxidizer vessel shell ID (ft) 52 63
Oxidizer pressure drop (psi) 1.8 0.4
Oxidizer FD Fan power (MW) 6.5 4.4
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O2-Carrier Conversion (Reducer)Performance Sensitivity
Fe2O3 Case
CaSO4 Case
• Fe2O3 conversion should be large to minimize solids circulation and Oxidizer FD Fan power
• CaSO4 conversion should be small to minimize H2 and CO off-gas loss
Source: NETL
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Carbon Gasification Efficiency (Reducer)Performance Sensitivity
Fe2O3 Case
• Char separation and recycle is necessary for feasible Reducer vessel size
• Carbon gasification efficiency > 95% is needed for CaSO4 system to achieve 90% carbon capture
CaSO4 Case
Reference Value
Reference Value
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O2-Carrier MakeupCost Sensitivity
• O2-carrier makeup is more significant issue for Fe2O3 than for CaSO4
• Cheaper, less reactive forms of Fe2O3 might be used (red mud, hematite)
Fe2O3 Case
CaSO4 Case
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Char/O2-Carrier & Ash SeparatorCost Sensitivity
• COE fairly insensitive to char/O2-carrier & ash separator cost (up to 10 x Reducer cost)• Char content in char/O2-carrier/ash mixture is very small• Effective mechanism for char separation not identified
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Conclusions/Implications from Sensitivity Cases
Parameter Fe2O3 CaSO4
Reducer Operating Temperature Operate with highest feasible temperature
Oxidizer Operating TemperatureInsensitive – operate with temperature high enough to
support reducer
Reactor Operating VelocitiesNo benefit from velocities above what is required to achieve
circulating bed operation
Gasification EfficiencyNeed >90% to achieve
90% C-capture; H2/CO loss small
Need > 95% to achieve 90% C capture; Need >95% to minimize H2/CO losses
Char/O2-Carrier SeparationRequired for feasible reducer size / Cost to achieve not prohibitive, but separation mechanisms not identified
O2-Carrier ConversionLarge (minimize solids
circulation and FD Fan power)Small (minimize H2 and CO
off-gas loss)
O2-Carrier Make-upFe-based O2-Carrier price
important; Need to minimize losses
Limestone makeup price not critical; Minimal losses
not critical
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For more info…
“Guidance for NETL’s Oxycombustion
R&D Program: Chemical Looping Combustion
Reference Plant Designs and Sensitivity Studies”
Report: DOE/NETL-2014/1643
http://netl.doe.gov/research/energy-analysis
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