Optimization of IGCC power plant Samantha Chase David Granum Ming Chen Tang Irena Vankova Sung Yoon Five Gasifiers

Project Definition  Improvements to existing Integrated Gasification Combined Cycle (IGCC)  Optimize an air separation unit (ASU) Decrease energy consumption in the current simulation Develop air separation alternatives  Minimize water usage in the overall process Decrease water requirements in the current simulation Suggest cooling alternatives

Integrated Gasification Combined Cycle COAL OXYGEN SYNGAS GASIFICATION Ignition ELECTRICITY AIR SEPARATION AIR NITROGEN POWER GENERATION

Outline  Air separation unit optimization  Optimization of existing unit  Cryogenic air separation alternatives  Non-cryogenic air separation alternatives  Water usage minimization  Water usage analysis  Process cooling alternatives  Economics  ASU comparison  Water versus air cooling  Environmental permitting  Future work

Optimization of the Air Separation Unit

12.0 MW O2 Compression Inlet Air Compression 0.85 atm 9.19 atm N2 Product Stream -180 °C 4.42 atm N2 Compression 4.42 atm -176 °C 2.18 atm -188 °C 2.18 atm 60 MW 12.3 MW 38.5 MW 16.5 MW O2 Product Stream -167 °C 4.42 atm

AIR atm 430 °C N atm 167 °C SYNGAS atm 40 °C atm 1310 °C 5.06 atm 1052 °C MW 2.13 atm 761 °C MW 0.90 atm 579 °C MW 5.06 atm 1139 °C MW 2.13 atm 906 °C MW 0.90 atm 561 °C 157 MW 259 MW N atm 37.5 °C 219 MW atm 1410 °C

Overall Results  ASU electricity improvements:  Original ASU electricity usage: MW  New ASU electricity usage: MW  30.4 MW Improvement  Gas turbine improvements:  Original electricity production: 309 MW  New electricity production: 319 MW  10.0 MW improvement  Overall: 40.4 MW Improvement  407 MW MW sent to grid

Alternative Energy Source  Wind Synergy  Wind turbines to power compressors  Adjacent Wind Farm  Wind turbines that send electricity to a power grid

Ion Transport Membrane (ITM)  Novel technology – Air Products, Praxair  Pilot plant 5 TPD of O 2  Mixed conducting non-porous ceramic membranes  100% oxygen selectivity  Single stage air separation – compact design  Savings on the ASU  35% on capital cost  37% on power requirements  Easy integration into the current process

°C High Partial Pressure Low Partial Pressure

Minimization of Water Usage

Water Profile by Block GASIFIER STEAM GENERATION COOLING TOWER AIR SEPARATION UNIT GAS TURBINE Boiling Feed Water Slurry Makeup Moisture in Cooling Air Cooling Water Makeup Moisture in Coal (28%) Cooling Water Evaporation Cooling Water Blowdown Moisture in Vent Moisture in Air Nitrogen Oxygen SyngasExhausted Flue Gas

Overall Water Balance WATER INWATER OUT Location Flow Rate (m 3 /hr) LocationFlow Rate (m 3 /hr) Raw Water 997 Ash Handling Blowdown2.2 Water with Slag0 Water Loss in COS Hydrolysis0.01 Sour Water Blowdown0.1 Cooling Tower Blowdown185 Cooling Tower Evaporation 809 Syngas Combustion in Gas Turbine218 Gas Turbine Flue Gas220 Combustion Air for Gas Turbine1.3 Moisture in Coal53Water Lost in Gasification53 Air Moisture to ASU0.5Moisture from ASU Vent0.5 TOTAL1269TOTAL1269

Raw Water Feed to the Plant

Water Usage and Heat Exchanger  Why? Most of water for heat exchanger  Shell-and-tube exchanger (default) WATER- CONSUMING… ROBUST!

Air Fin – Cooling Alternative  Atmospheric air is a cooling medium

Economics

Basis for Economic Evaluation  Project period: 20 years  Discount factor: 10%  Inflation: 4%  Installation factor: 504%  Working capital: 20% of fixed capital investment (FCI)  Tax rate: 35%  Costs: positive  Disregard constants common for all alternatives  e.g. Oxygen product constant for all ASUs  Compare net present values (NPV)  No internal rate of return (IRR) or payback period

ASU Capital Cost Comparison

ASU Utility Cost Comparison

NPV10 Sensitivity – ASU Capital Cost

NPV10 Sensitivity – ASU Utility Cost

Evaluation of Cooling Alternatives

Shell-and-Tube vs. Air Fin – Econ Analysis Shell-and-TubeAir Fin Fixed Capital Investment $ 1,900,000$ 8,800,000 Variable Cost $ 400,000$ 0  Construct incremental cash flow (CF): 1)Case 01: Incremental CF = Shell-and-Tube CF – Air Fin CF 2)Case 02: Incremental CF = Air Fin CF – Shell-and-Tube CF Case 01 (CW) Case 02 (AF) NPV10$ 1,800,000- $ 1,800,000

Environmental Permitting  Solid Waste-permit acquired through Wyoming’s DEQ Solid & Hazardous Waste Division  Sludge is regulated as ‘solid waste’; products of SO 2, Hg, and acid gas removal ‘hazardous waste’  Air Emissions-Title V operating permit acquired through DEQ Air Quality Division  Process meets all emission regulations for coal plants lb SO 2 << 0.3 lb SO 2 / 10 6 BTU  Recently (March 2011), EPA announced it will regulate mercury and acid gas in coal State of Wyoming is currently suing the EPA  Potential for future CO 2 regulations Process contains CO 2 removal and compression unit

Conclusions & Future Work  Conclusions  Improved cryogenic ASU design  Air fins instead of water cooling  Suggestions for future work  Heat integration  Continue to monitor ASU technology improvements Argon separation Membrane separation

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