Principle And Operation Of The 200kW Phosphoric Acid Fuel Cell Station In Panyu

Fuel cells have been regarded as one of the most valuable technologies, because they have many advantages such as the high efficient, friendly environmental energy conversion. Developed countries are active in fuel cells and have reached a lot of achievements. Fuel cell technology is less developed in China. Up to now, we have not yet owned any fuel cell with high power built by ourselves.An agreement between Chinese government and the institute of energy economics of Japan was signed in Dec 1999, which is about the building of 200kW phosphoric acid fuel cell station in Panyu , Guangdong Province .The station uses the biogas as the fuel sources for the fuel cell. It also includes waste water treatment and composing system. The station was completed in Dec 2004.The purpose of this thesis is to give a detailed information on the working principles of this station and the results obtained by running individual system and whole system.1. The station includes following systems: fermentation, desulfuriztion, fuel cell system, water treatment and composting system. The fermentation system and the desulfuriztion system are used to support fuels for the fuel cell. The fuel cell system is the core of the fuel cell station, and it is used to generate electricity. The water treatment system and the composting system are used to purify waste water and produce composting by using the waste.2. The anaerobic fermentation is operated under mild conditions, with animalcule, the chemical oxygen demand (COD) in the waste water is turn to biogas. The quality of the biogas reaches the request of the fuel cell by desulfurizing. Results obtained by running this system show that the conversion efficiency of the COD is about 70%,and the daily output of the biogas can reach 450m3 at 33-35 ℃, at this stage there are only 6000 pigs available . After desulfurizing , the H₂S in the biogas is under 6ppm and which can meet the request of the fuelcell running.3. The fuel cell system is the core part of the station. It can be divided into direct current (DC) system and electrical (EC) system. The DC system includes power section system, air processing system, fuel processing system, thermal management system, water treatment system, nitrogen purge system and cabinet ventilation system .The EC system includes power conditioning system, power distribution system and power plant controller. The output voltage of the fuel cell will decrease as running the fuel cell but the decreased value doesn't exceed 0.1V. The conversion efficiency of methane to hydrogen in the fuel is 95.1%. The usage efficiency of hydrogen in the fuel is 78.6% .The usage efficiency of oxygen is 57.7%. Because the amount of the biogas at this stage cannot meet the need of continuous running of the fuel cell, so we put forward one feasible project for the fuel cell running.4. The waste water treatment system is an important part of the station. It treats the waste water from the fermentation system with active aerobic sludge method and cohesion deposition method. After treatment biochemical oxygen demand(B0D5) is 103mg, COD 44.3 mg, suspension substance (SS) 18 mg, NH3-N 120 mg, total phosphorus (T-P) 0.8 mg, coliform 20 in every litre in treated water. The content of NH3-N cannot reach the national standard. So the management of the waste water treatment should be improved greatly.5. The composting system uses the aerobic composting to produce valuable fertile and prevent the second pollution. After composting, the volatility substance (VS) descends obviously, the total nitrogen (T-N) descends unconspicuously, the T-P increases little, the water content in the fertilizer descends obviously and the data of the total solid (TS) increase obviously.