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Heat. Fuel Cell. REVISION LIST -- To be removed before final presentation .JMH -- 20/april/05 3:30 pm I’ve rearranged some of the nick slides -- it is more in line with the “flow” of the process. I’ve taken some things out.
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Heat Fuel Cell REVISION LIST -- To be removed before final presentation .JMH -- 20/april/05 3:30 pm I’ve rearranged some of the nick slides -- it is more in line with the “flow” of the process. I’ve taken some things out. I’ve made the background with header & footer on all but Title slide I added the PFD repeatedly in nick’s section to “bring the viewer back home” I’ve partially covered the non-circled parts of the PFD when showing a new section I’ve enlarged all the PFD images to max I put some of your pictures here & there I’ve added the “Turn it over” introductions I’ve revised and corrected the fuel cell details
Fuel Cell Design ENCH 340 Spring, 2005 UTC
Technical and EconomicAspects of a 25 kW Fuel Cell Chris Boudreaux Jim Henry, P.E. Wayne Johnson Nick Reinhardt
Technical and EconomicAspects of a 25 kW Fuel Cell • Chemical and Thermodynamic Aspects Our Competence Investigate the design of --a 25 kW Fuel Cell --Coproduce Hydrogen --Grid parallel --Solid Oxide Electrolyte Not Our Competence
Outline Introduction to the project Process Description Process & Equip. Design Economic Analysis
Introduction Overall Reaction Methane + Air --> Electricity + Hydrogen + Heat + CO2
Introduction Gas Reformer Water SynGas Electricity Air Fuel Cell Heat POC Hydrogen Pressure Swing Absorption Exhaust
Fuel Cell-Chemistry SynGas POC H2 + CO H2 H2O CO2 CO O- O- “Air” Air O2 N2 Solid Oxide Electrolyte Is porous to O-
Fuel Cell-Electricity Electrons SynGas POC H2 H2O CO2 CO Load O- O- “Air” Air O2 N2
Fuel Cell-Challenges SynGas POC H2 Hot SynGas + CO H2 H2O CO2 CO Recover H2 O- O- “Air” Air O2 N2 Hot Air Recover Heat
Desulfurizer (DS 101) • 2 ppm H2S in natural gas feed • H2S removed in DS-101 with disposable carbon filters • 10% of CH4 fed to combustor • 90% of CH4 fed fuel humidifier
Fuel Humidifier (FH 102) • 1.25 Kmol H20 per Kmol CH4 fed to FH-102 • Heat provided from combustor exhaust
Fuel Preheater (HX 103) • Heat provided from fuel cell exhaust
Reformer (R 104) • Equilibrium determined to be: • 85% CH4 → CO • 15% CH4 → CO2 • CH4 + H2O → CO + 3H2 • CH4 + 2H2O → CO2 + 4H2 • Heat provided from reaction in combustor
Combustor (COMB 105) • Extent of reaction for combustion assumed to be 100% • CH4 + 2O2 → CO2 + 2H2O • Necessary O2 provided from fuel cell air exhaust
Air Compressor (COMP 224) • Air intake for the system • 6.65 standard cubic meters per minute flow
Air Preheater (HX 223) • Heat provided by water gas shift exhaust
Water Gas Shift (WGS 222) • CO + H2O → CO2 + H2 • Equilibrium determined to be 94%
Air Side Heat Recovery (HX 221) • Heat provided by combustor exhaust
Fuel Exhaust Condenser (HX 443) • Uses external cooling source • Condenses process water from exhaust gases • Condensed water flows to WP-441 • Non-condensible exhaust flows to comp-445 and PSA system • 99.5% of water is condensed
Chiller (Ref 446) • Provides cold water utility for HX-443 • Supply temp = 0C • Return temp = 50C • Rate = 1.8 gpm • Cooling = 35,500 kJ/hr (9.9kW) • Power = 2.4 kW to run
PSA Compressor (COMP 445) • Provides dried, compressed exhaust gas to the PSA system. • 2 stage compressor
Pressure Swing Adsorber (PS 442) • Uses custom adsorbant to purify hydrogen • 80-90% recovery possible • 99.9+ purity on the product gas achievable with slight recovery cost • Delivery pressure 20 bar • Recovered Hydrogen = .177 kmol/hr @ 90%
Hydrogen Compressor (COMP 447) • Produced compressed hydrogen for sale • Multi-stage compressor • Pressure input = 2-20 bar • Pressure output = 200 bar
Water Purifier (WP 441) • Basic cartridge filtration of incoming water (either city supply or process supply) • Excess process water discharged to city sewer
Water Pump (P 444) • Supplies water to section 100 fuel humidifier
Equipment Assumptions • All equipment was assumed to be stainless steel
Heat Exchangers • 10° approach temperature was used • q = UAFΔTlm • F = 0.9 • U = 30 W/m2°C • ΔTlm = (ΔT2 – ΔT1) / [ ln(ΔT2 / ΔT1) ]
Pumps and Compressors • Power = mz1RT1[({P2/P1}a – 1)]/a • T1 = inlet temp • R = Gas Constant • Z1 = compressibility • m = molar flow rate • a = (k-1)/k • k = Cp / Cv
Other • PSA, WGS, and desulfurizer have purchased internals
Economic Components • Capital Costs • Operating Costs • Income Generated • Payback Period • Return on Investment
Capital Cost Assumptions • Cap Cost Program • Stainless Steel • Minimum Size Basis for all components
Sizing Adjustments • Equation from Text Ca/Cb = (Aa/Ab)n • Ca = Cost of Desired Equipment • Cb = Cost of Base Equipment • Aa = Desired Cost Attribute • Ab = Base Cost Attribute • n = Cost Exponent (0.6)