Driving Innovation Delivering Results CHEMICAL LOOPING COMBUSTION REFERENCE PLANT DESIGNS AND SENSITIVITY STUDIES Robert Stevens, Ph.D. US Dept. of Energy NETL September 1, 2015
Chemical Looping Combustion Basics CO 2 & H 2 O O 2 -depleted Air Fuel: Coal Natural Gas Make-up Carrier Reducer Me Heat Recovery MeO Oxidizer Reducer: CH X + MeO CO 2 + H 2 O + Me Oxidizer: Me + O 2 MeO Steam Air Ash 2
Objectives Develop Reference coal-based CLC power plant reactor models and process simulations Fe 2 O 3 oxygen-carrier CaSO 4 oxygen-carrier Estimate power plant performance and cost Estimate power plant component performance and cost sensitivities to key design parameters Guide research and development 3
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 CO 2 product purity at least 95 mol% CO 2 product delivery pressure: 2200 psig Major equipment performance and cost assumptions consistent with the NETL Bituminous Baseline report 4
CFB CLC Plant Block Flow Diagram Recovered fuel to oxidizer Oxidized Reduced Fe 2 O 3 Fe 3 O 4 CaSO 4 CaS Source: NETL 5
CLC Reference Plant Overall Performance and Cost Results Oxygen-carrier type Fe 2 O 3 CaSO 4 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 CO 2 Product Purity (mole% CO 2 / ppmv O 2 ) 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 ($/MWh) w/o T&S Reduction in COE (%) [Reference IGCC w/ CCS] 115.2 104.7 137.3 (2) 13.4% 21.3% ~0% 1. DOE/NETL-2010/1397, Cost and Performance Baseline for Fossil Energy Plants Volume 1: Bituminous Coal and Natural Gas to Electricity, Rev. 2 (Nov. 2010) 2. DOE/NETL-341/082312, Updated Costs (June 2011 Basis) for Selected Bituminous Baseline Cases (Aug. 2012) 6
Reference Plant Cost Breakdown (2011$/kW) Fe 2 O 3 CaSO 4 SCPC w/ Cap CLC System (or Boiler & CO 2 sys) 729 785 795 + 920 Reactors, Cyclones, and piping 87 102 n/a Char/O 2 -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 CO 2 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 7
Reference Plant COE Breakdown (2011$) Fe 2 O 3 ($/MWh) CaSO 4 ($/MWh) SCPC w/ Cap ($/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 O 2 -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 Fe 2 O 3 oxygen-carrier makeup: 132 tons/day @ $2,000 per ton Limestone O 2 -carrier makeup: 439 tons/day @ $33.5 per ton 8
Reducer Sensitivity Parameters Oxygen-Carrier Type Fe 2 O 3 CaSO 4 Reference Plant Fixed Parameters Sensitivity Parameters & Reference Plant Values Sensitivity Characteristics & Reference Plant Values Steam feed rate (moles/mole C) 0.44 0.44 Recycle-CO 2 feed rate (moles/mole C) 0.031 0.031 Oxygen-carrier inlet extent of conversion Fe 2 O 3 to Fe 3 O 4 or CaSO 4 to CaS 0.069 0.0 Cyclone recycle ratio 4:1 4:1 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 Reducer vessel height (ft) 115 87 Reducer vessel shell ID (ft) 39 41 Reducer pressure drop (psi) 21.4 2.9 Reducer off-gas H 2 & CO (mole%) 0.05 1.5 9
Oxidizer Sensitivity Parameters Oxygen-Carrier Type Fe 2 O 3 CaSO 4 Off-gas oxygen content (mole%) 3.5 3.5 Reference Plant Fixed Parameters Sensitivity Parameters & Reference Plant Values Sensitivity Characteristics & Reference Plant Values Oxygen-carrier inlet extent of conversion 0.313 0.823 Cyclone recycle ratio 3:1 3:1 Oxygen-carrier outlet extent of conversion Fe 3 O 4 to Fe 2 O 3 or CaS to CaSO 4 0.931 1.0 Oxidizer temperature ( F) 1800 2000 Oxidizer inlet gas velocity (ft/s) 32 30 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 10
O 2 -Carrier Conversion (Reducer) Performance Sensitivity Fe 2 O 3 Case CaSO 4 Case Fe 2 O 3 conversion should be large to minimize solids circulation and Oxidizer FD Fan power CaSO 4 conversion should be small to minimize H 2 and CO off-gas loss Source: NETL 11
Carbon Gasification Efficiency (Reducer) Performance Sensitivity Reference Value Fe 2 O 3 Case Reference Value CaSO 4 Case Char separation and recycle is necessary for feasible Reducer vessel size Carbon gasification efficiency > 95% is needed for CaSO 4 system to achieve 90% carbon capture 12
O 2 -Carrier Makeup Cost Sensitivity Fe 2 O 3 Case CaSO 4 Case O 2 -carrier makeup is more significant issue for Fe 2 O 3 than for CaSO 4 Cheaper, less reactive forms of Fe 2 O 3 might be used (red mud, hematite) 13
Char/O 2 -Carrier & Ash Separator Cost Sensitivity COE fairly insensitive to char/o 2 -carrier & ash separator cost (up to 10 x Reducer cost) Char content in char/o 2 -carrier/ash mixture is very small Effective mechanism for char separation not identified 14
Conclusions/Implications from Sensitivity Cases Parameter Fe 2 O 3 CaSO 4 Reducer Operating Temperature Operate with highest feasible temperature Oxidizer Operating Temperature Reactor Operating Velocities Gasification Efficiency Char/O 2 -Carrier Separation O 2 -Carrier Conversion Insensitive operate with temperature high enough to support reducer No benefit from velocities above what is required to achieve circulating bed operation Need >90% to achieve 90% C-capture; H 2 /CO loss small Need > 95% to achieve 90% C capture; Need >95% to minimize H 2 /CO losses Required for feasible reducer size / Cost to achieve not prohibitive, but separation mechanisms not identified Large (minimize solids circulation and FD Fan power) Small (minimize H 2 and CO off-gas loss) O 2 -Carrier Make-up Fe-based O 2 -Carrier price important; Need to minimize losses Limestone makeup price not critical; Minimal losses not critical 15
For more info http://netl.doe.gov/research/energy-analysis Guidance for NETL s Oxycombustion R&D Program: Chemical Looping Combustion Reference Plant Designs and Sensitivity Studies Report: DOE/NETL-2014/1643 16
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