Fuel Cell Design Chemical Engineering Senior Design Spring 2005 UTC

Technical and Economic Aspects of a 25 kW Fuel Cell Chris Boudreaux Wayne Johnson Nick Reinhardt

Technical and Economic Aspects of a 25 kW Fuel Cell Investigate the design of --a 25 kW Fuel Cell --Coproduce Hydrogen --Grid parallel --Solid Oxide Electrolyte Chemical and Thermodynamic Aspects Our Competence Not Our Competence

Outline Introduction to the project Process Description Process & Equip. Design Economic Analysis

Introduction Overall Reaction Methane + Air --> Electricity + Hydrogen + Heat + CO 2

Introduction Pressure Swing Adsorption Fuel Cell Reformer Gas Hydrogen Electricity Air Heat SynGas POR Water Exhaust

Fuel Cell-Chemistry SynGas Air O-O- O-O- H2H2 H2OH2O CO CO 2 POR O 2 N 2 “Air” Solid Oxide Electrolyte is porous to O - H2H2 + CO

Fuel Cell-Electricity SynGas Air O-O- O-O- H2H2 H2OH2O CO CO 2 POR O 2 N 2 “Air” Electrons Load

Fuel Cell-Challenges SynGas Air O-O- O-O- H2H2 H2OH2O CO CO 2 POR O 2 N 2 “Air” H2H2 + CO Hot SynGas Hot Air Recover H 2 Recover Heat

Process Description Turn it over to Nick Reinhardt

SOFC PFD

Fuel Preparation - 100

Desulfurizer (DS-101) Removes trace amounts of Sulfur

Fuel Humidifier (FH-102) 1.25 Kmol H 2 0 per Kmol CH 4 Heat provided from combustor exhaust

Fuel Preheater (HX-103) Heat provided from fuel cell POR exhaust

CH 4 + H 2 O → CO + 3H 2 (85%) CH 4 + 2H 2 O → CO 2 + 4H 2 (15%) Heat provided from reaction in combustor Reformer (R-104)

Combustor (COMB-105) CH 4 + 2O 2 → CO 2 + 2H 2 O(100%) Necessary O 2 provided from fuel cell air exhaust

SOFC PFD

Air Handling and WGS - 200

Air Compressor (COMP-224) Air intake for the system

Air Preheater (HX-223) Heat provided by WGS exhaust

Water Gas Shift (WGS-222) Consumes CO CO + H 2 O → CO 2 + H 2 (72%)

Air Side Heat Recovery (HX-221) Heat provided by combustor exhaust

SOFC PFD

Fuel Cell - 300

Fuel Cell (FC-331) CO + ½ O 2 → CO 2 (95%) H 2 + ½ O 2 → H 2 O (60%)  H to electricity = 50%

SOFC PFD

Post Processing - 400

Fuel Exhaust Condenser (HX-443) Condenses process water from exhaust gases

Chiller (Ref-446) Provides cold water utility for HX-443

PSA Compressor (COMP-445) Provides dried, compressed exhaust gas to the PSA system

Pressure Swing Adsorber (PSA-442) Purifies hydrogen

Compressed hydrogen for sale Hydrogen Compressor (COMP-447)

Water Purifier (WP-441) Purifies process water

Water Pump (P-444) Supplies water to fuel humidifier

Process and Equipment Design Turn it over to Chris Boudreaux

SOFC PFD

Heat Exchangers A=q/UFΔT lm F = 0.9 U = 30 W/m 2 °C ΔT lm = (ΔT 2 – ΔT 1 ) / [ ln(ΔT 2 / ΔT 1 ) ]

Pure Natural Gas 25°C 0.33 kmol/hr CH 4 = 100% Sulfur Purge 25°C kmol/hr H 2 S = 100% Natural Gas Inlet 25°C 0.33 kmol/hr CH 4 = 99.9% H 2 S = 0.001% Desulfurizer

Recycled Water 5°C 0.37 kmol/hr H 2 O = 100% Cooled POC 283°C 3.51 kmol/hr N 2 = 86% O 2 = 9% H 2 O = 4% CO 2 =1% Humidified NG 273°C 0.67 kmol/hr H 2 O = 56% CH 4 = 44% Pure NG 25°C 0.3 kmol/hr CH 4 = 100% POC Vent 26°C Fuel Humidifier Area = 2.6 m 2 q = 1.8 kW

Heated HNG 840°C Cooled POR 479°C POR 850°C 1.3 kmol/hr H 2 O = 47% H 2 = 29% CO 2 = 23% CO = 1% Humidified NG 273°C Fuel Preheater Area = 6.3 m 2 q = 5.3 kW

Heated HNG 840°C 0.67 kmol/hr H 2 O = 56% CH 4 = 44% SynGas 734°C 1.26 kmol/hr H 2 = 73% CO = 21% H 2 O = 3% CO 2 = 2% Reformer R-104 q = 17 kW R-104 COMB-105 Heated HNG SynGas POC Depleted Air Pure NG CH 4 + H 2 O → CO + 3H 2 CH 4 + 2H 2 O → CO 2 + 4H 2

Combustor COMB-105 Depleted Air 850°C 3.48 kmol/hr N 2 = 87% O 2 = 11% H 2 O = 2% POC 784°C 3.51 kmol/hr N 2 = 86% O 2 = 9% H 2 O = 4% CO 2 =1% Pure NG 25°C 0.03 kmol/hr CH 4 = 100% q = -17 kW R-104 COMB-105 CH 4 + 2O 2 → CO 2 + 2H 2 O SynGas POC Heated HNG Depleted Air Pure NG

Cooled POR 480°C 1.3 kmol/hr H 2 O = 47% H 2 = 29% CO 2 = 23% CO = 1% WGS Exhaust 480°C 1.26 kmol/hr H 2 O = 46.5% H 2 = 30% CO 2 = 23.2% CO = 0.3% Water Gas Shift Reactor CO + H 2 O → CO 2 + H 2

POR 850°C 1.3 kmol/hr H 2 O = 47% H 2 = 29% CO 2 = 23% CO = 1% Depleted Air 850°C 3.48 kmol/hr O 2 = 11.5% Heated Air 650°C 3.88 kmol/hr O 2 = 21% SynGas 750°C 1.26 kmol/hr H 2 = 73% CO = 21% H 2 O = 3% CO 2 = 2% Fuel Cell CO + ½ O 2 → CO 2 H 2 + ½ O 2 → H 2 O

H Exhaust 25°C 0.38 kmol/hr H 2 = 100% Purge 25°C 0.43 kmol/hr CO 2 = 68% Uncondensed Gases 5°C 0.68 kmol/hr H 2 = 56% CO 2 = 43% Air Inlet 25°C 0.13 kmol/hr Pressure Swing Adsorber

Economic Analysis Turn it over to Wayne Johnson

Economic Components Capital Costs Operating Costs Income Generated Payback Period Return on Investment

Capital Cost Assumptions Cap Cost Program –Analysis, Synthesis, and Design of Chemical Processes –Compares to Peters and Timmerhaus Stainless Steel

Equipment Costs

Lang Factor Fluid Processing = 4.74 Includes: –Construction material and overhead –Labor –Contract engineering –Contingency –Site development $40,000 X 4.74 = $190,000

Operating Costs Fuel: 0.33 kmol/hr = 260,000 BTU/hr = 0.26 therms/hr Tennessee Valley industrial rate = $7.70/therm Labor included at site

Income Electricity = 25kW Price = $0.10/kWhr Hydrogen = 0.38 kmol/hr =.76 kg/hr Tennessee Valley industrial rate = $11.64/kg

Total Income vs. Expense

Investment Results Non-discounted Payback = 2.4 Years Return on Investment = 41%

Conclusions Rate of return and payback period are interesting Emerging technology means cost may decrease

Questions for the Board What areas require more detail? What locations should be investigated? Should we enlist an electro-chemistry team? Should we enlist an electrical engineering team?