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Факультет: электротехнический (ЭТФ)

Кафедра: электротехнических станций (ЭС)

Специальность: «Электрические станции» (ЭС)

Тема магистерской работы:

Автоматизачия проектирования электрической части тепловых электростанций работающах на органическом топлве в условиях Нигерии.

Научный руководитель: Павлюков Валерий Александрович

Библиотека по теме выпускной работы

Собственные публикации и доклады

200 KW HYDROGEN FUELED FUEL CELL POWER PLANT

200 KW HYDROGEN FUELED FUEL CELL POWER PLANT
Valerie Maston
International Fuel Cells
South Windsor, CT 06074

Abstract
IFC has designed a hydrogen fueled version of its standard PC25t C fuel cell power plant. The standard PC25tC is a 200 kW, natural gas fueled phosphoric acid fuel cell power plant that is commercially available. The program to accomplish the fuel change involved deleting the natural gas processing elements, designing a newfuel pretreatment subsystem,modifying thewater and thermal management subsystem, developing a hydrogen burner to combust any unconsumed hydrogen, and modifying the control system. Additionally, the required modifications to the manufacturing and assembly procedures necessary to allowthe hydrogen fueled power plant to bemanufactured in conjunction with the on--going production of the standard PC25tC power plants was identified. This
work establishes for theDOE the design andmanufacturing plan for the first commercially available 200 kW hydrogen fueled fuel cell power plant.

Introduction
IFC has designed an optimized 200 kWPAFC hydrogen fueled power plant for commercial production. The basis for this programis IFC’s commercially available natural gas fueled PC25tC power plant and an existing demonstration hydrogen power plant for a European customer. To meet the program goals, IFC developed a hydrogen fuel specification, designed an optimized power plant to operate on the specified fuel, identified an improvedmanufacturing process for the newpower plant, and as cost share activity developed cell stack improvements.

Hydrogen Fuel Specification

Asurvey of available hydrogen fuelswas conducted to provide a basis for the fuel specification. The available sourceswere found to be commercial pressurized hydrogen gas, commercial liquefied hydrogen, hydrogen gas from electrolysis, and hydrogen rich gas by--product from the Chlor--Alkali and Petroleum Industries. Table 1 is the summary of the hydrogen fuel sources and their compositions. Table 1. Summary of Hydrogen Fuel Sources Renewables Oglethorpe Ashland Air Products Praxair Solar/Wind OxyTech Power Petroleum
Chlor--Alkali Customer
Std--Purity Ind--Grade Electrolysis (diaph. cell) Chlorate Petroleum
Liquid Gas Gas Product By--Product By--Product By--Product
Hydrogen, % >99.999 >99.95 >99.99 >99.95 99.7--99.8 92.68 86.5
ppm
Oxygen <2 <5 <10 1500--2500 18500
Argon <10
Nitrogen <5 <400 <100 <10 40--200 5000
Methane <4 <10 <10 39000
Ethane 40000
Propane 28000
Isobutane 8000
n--Butane 6000
Pentanes & heavier 9000
Carbon Dioxide <10 0--800
Carbon Monoxide <3 trace
CO + CO2 <1 <10
NaOH 500--700
NaCl 5--10
Chlorine 0.3
Chlorine Dioxide 0.3
Ammonia 6

Except for the hydrogen rich gas fromthe PetroleumIndustry, all the other sources of hydrogen fuel were at least 98%hydrogen on a dry basis. The hydrogen rich gas by--product fromtheChlor--Alkali Industry, which includes hydrogen from both chlorine and chlorate production, has unacceptably high levels of oxygen and depending on the type of cell used has high levels of chlorine, ammonia, salts, or mercury. The wide range of possible contaminants from the Chlor--Alkali gas made it impossible to establish one gas clean up system for all the Chlor--Alkali off--gases. The Petroleum Industry hydrogen rich fuel is being addressed separately. This hydrogen rich gas by--product contains substantial amounts of heavy hydrocarbons. These hydrocarbons represent 50% of the heating value of the gas even though they only represent a mole fraction of 15%. Two methods of using such a hydrogen rich gas sources are being examined. The first is using activated carbon beds to remove the heavy hydrocarbons prior to the hydrogen power plant. The othermethod being evaluated is using this gas in a natural gas PC25tC with amodified reformermatched to the petroleumby--product gas. Themethodswill be compared based on the estimated design and development
costs of each system. Afinal recommendation on the approach to be used for the Petroleum Industry gas will be made once the evaluation of the two methods is completed.

Hydrogen Power Plant Specification

The hydrogen power plant design was based on the hydrogen fuels identified in Task 1. The results of this effort yielded an improvement of 2%in the electrical efficiency above the existing hydrogen power plant design. For this program, cell testing and stack modeling were done to establish flow conditions thatwould allowfor the power plant to be over 44%electrically efficient. The stack cooling flows were changed which optimized steamproduction and reduced the number of components. A hydrogen burner was placed in the anode exhaust stream, which allowed for the removal of the acid scrubber and cupola from the demonstration design. The manufacturing procedures were reviewed andmodifications weremade to the design that optimize the build sequence and time to produce the power plant. The following options currently available on the natural gas power plant were incorporated into this design. This power plant, unlike the existing hydrogen power plant, can be operated either grid connected or grid independent. There are two possible high grade heat options available for this power plant. The first one uses the hotwater in the cooling loop to provide the customerwith up to 300,000 BTU/hr of 250° F thermal energy. The second option, exclusive to the hydrogen power plant, includes the first option plus takes advantage of excess steam that can be produced by the stack. This
second option allows for over 400,000 BTU/hr of high grade heat at 250° F to be removed from the power plant. This unit is a 60 Hz unit.
Cell Stack Improvements IFC’s cost share on this program was in the area of cell stack improvements. Two specific repeat parts, the separator plates and the coolers, were improved in this program. Several production trial lots were run to optimize production and improve the separator performance. The separator plate design that was selected had improved (reduced) permeability and a higher yield. This separator plate design has now been incorporated into the production bill ofmaterial. The development work on the coolers examined going to a molded cooler. Molding the cooler plates, will improve the
manufacturing process. Also,methods of increasing the cooler heat transferwere examined. At the completion of the cost share activity, themolded coolers had passed the initial testing andwere being prepared to be tested in a full area substack. If the subsequent testing is successful, molded coolers will be incorporated into the production bill of material in 1998.

Conclusion

The hydrogen power plant design increased the electrical efficiency of the power plant to over 44% for this design as compared to 40% for natural gas and 42% for the existing hydrogen power plant. Delivery of high grade heatwas determined to be feasible and two optionswere identified. The number of components was reduced and themanufacturing process was optimized. At the conclusion of this programtherewill be a hydrogen power plant design that can be produced at a commercial scale and this power plant will be compatible with renewable hydrogen fuel sources.

Acknowledgements

IFCwould like to acknowledge theDOE for their funding of this programand the following individuals and companies for their contribution to our fuel survey:
T. F. Florkiewicz of OxyTech Systems, Inc. Tom Halverson of Praxair, Inc. Jim McElroy of Hamilton Standard
Venki Raman of Air Products and Chemicals, Inc. Robert H. Wombles of Ashland Petroleum Company