United States Environmental Protection Agency National Risk Management Research Laboratory Research Triangle Park, NC 27711 Research and Development EPA/600/SR-95/155 April 1996 EPA Project Summary Demonstration of Fuel Cells to Recover Energy from Landfill Gas - Phase II. Pretreatment System Performance Measurement J.S. Trocciola The report describes Phase II of a demonstration of the utilization of com- mercial phosphoric acid fuel cells to recover energy from landfill gas. This phase consisted primarily of the con- struction and testing of a Gas Pretreat- ment Unit (GPU) whose function is to remove those impurities from landfill gas which are detrimental to the fuel cell. The GPU has been successfully tested at a landfill-to-energy facility in Los Angeles (Sun Valley), California. The GPU successfully removed the sul- fur and halogen compounds contained in the landfill gas to a level signifi- cantly below that specified for use with the phosphoric acid fuel cell. During a challenge test in which dichlorodifluo- romethane (Refrigerant 12) was inten- tionally injected into the process stream during an 8-hour period, the exit con- centration of Refrigerant 12 was below the limit of detection and below the specified value for the fuel cell. This Project Summary was devel- oped by EPA's National Risk Manage- ment Research Laboratory's Air Pollu- tion Prevention and Control Division, Research Triangle Park, NC, to an- nounce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering at back). Overview International Fuel Cell Corporation (IFC) has completed Phase II of a U.S. Environ- mental Protection Agency (EPA) demon- stration of the utilization of commercial phosphoric acid fuel cells to recover en- ergy from landfill gas. This phase of the program consisted primarily of the con- struction and testing of a Gas Pretreat- ment Unit (GPU) whose function is to re- move those impurities from landfill gas which are detrimental to the fuel cell. The GPU has been successfully tested at a landfill site located in Los Angeles (Sun Valley), California. The site is oper- ated by Pacific Energy Corporation as a landfill-to-energy facility. The GPU suc- cessfully removed the sulfur and halogen compounds contained in the landfill gas to a level significantly below that specified for use with the phosphoric acid fuel cell. During a challenge test in which dichlo- rodifluoromethane (Refrigerant 12) was intentionally injected into the process stream during an 8-hour period, exit con- centration of Refrigerant 12 was below the limit of detection and below the speci- fied value for the fuel cell. The GPU was constructed by IFC at its facility in South Windsor, Connecticut. Con- struction of the unit was completed in Feb- ruary 1993. Upon completion of construc- tion, the unit was evaluated at the South Windsor facility using nitrogen as the test gas. The unit successfully completed the 16-hour control test verifying that rated flows, pressure, and temperature were achieved. After the test, the unit was shipped to the landfill site in Los Angeles, California, where it was installed in April 1993. The GPU system is shown schemati- cally in Figure 1. The system consists of a number of fixed beds and condensers/ heat exchangers. A functional description of the major elements of the GPU is con- ------- tained in Table 1. The unit has been tested on landfill gas at the site, and Table 2 compares the measured sulfur and halide contents of the gas produced by the GPU to the specification value. The data verify that the GPU reduces the sulfur and ha- lide contents of landfill gas to a concen- tration lower than required by the fuel cell power plant. The data also show that liq- uids do not condense in the low tempera- ture cooler. However, that cooler reduces the temperature of the landfill gas prior to its introduction into the carbon bed, in- creasing the capacity of the carbon bed for the sulfur and halogen compounds. For system simplification in the future, it may be beneficial to eliminate the low temperature cooler and accept any reduc- tion in carbon bed capacity. Based on the favorable results of the GPU testing, the EPA directed IFC to proceed into Phase III of the program which entails character- izing the performance (i.e., emissions, ef- ficiency, and power output) of the com- mercial phosphoric acid fuel cell power plant when operating on landfill gas which has been purified by the GPU. Landfill Gas Regeneration Gas Clean Landfill Gas to Fuel Cell Figure 1. Landfill gas pretreatment system. Table 1. GPU Component Functions Component Function Regenerate H2S Removal Bed Cooler/Condenser Dryer Bed Low Temperature Cooler Carbon Bed Filter Remove H2S Remove Water, Hydrocarbons Remove Water to -50°C Dew Point Cool Carbon Bed Remove Organic Sulfur and Halogen Compounds Remove Particulates No Not Applicable Yes Not Applicable Yes No Table 2. GPU Sulfur and Halide Contaminant Removal Performance vs. Specification GPU Exit (ppmV) Specified Value (ppmV) Total Sulfur (as HSf Total Halides (as Chloride)" <_ 0.047 < 0.032 <3 <3 * Measured by gas chromatography/flame photometric detector by EPA Methods 15, 16, and 18. b Measured by gas chromatography/mass spectroscopy by EPA Method TO-14. ------- J.S. Trocciola is with International Fuel Cells Corp., South Windsor, CT 06074. Ronald J. Spiegel is the EPA Project Officer (see below). The complete report, entitled "Demonstration of Fuel Cells to Recover Energy from Landfill Gas - Phase II. Pretreatment System Performance Measurement," (Order No. PB96-103 601; Cost: $35.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Air Pollution Prevention and Control Division National Risk Management Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 United States Environmental Protection Agency National Risk Management Research Laboratory (G-72) Cincinnati, OH 45268 Official Business Penalty for Private Use $300 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 EPA/600/SR-95/155 ------- |