chemical looping combustion reference plant...

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

2National Energy Technology Laboratory

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


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


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


CFB CLC Plant Block Flow Diagram

Source: NETL

Recovered fuel to oxidizer

Oxidized ReducedFe2O3 Fe3O4

CaSO4 CaS


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)


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


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


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


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


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


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


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


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


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


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

http://netl.doe.gov/research/energy-analysis


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