JP3911540B2 - Fuel cell power generation system using waste gasification gas - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power generation system that generates electricity using pyrolysis gasification gas of waste as a fuel for an internal reforming molten carbonate fuel cell, and relates to an energy conversion and utilization technique.
[Prior art]
Conventionally, a practical system using waste gasification gas as fuel for an internal reforming molten carbonate fuel cell is not generally known. Therefore, FIG. 3 shows an internal reforming molten carbonate fuel cell power generation system using natural gas as a fuel as a similar technique. The natural gas N that has been pressurized by the fuel booster blower 31, desulfurized by the desulfurizer 32, and particulate matter removed by the filter 33 is supplied to the fuel humidifier 34, heated by the exhaust gas E from the fuel cell MCFC, and treated water W ′. Is humidified. Further, in order to prevent carbon deposition, a small amount of hydrogen gas is generated by the pre-converter 35, heated to about 600 ° C. by the fuel superheater 8, and then supplied to the fuel cell together with air AR from another system and used for power generation. . The exhaust gas from the fuel cell is recovered at about 400 ° C. after being recovered by the fuel superheater and the fuel humidifier. FIG. 4 shows a structural diagram of the fuel humidifier.
[0002]
[Problems to be solved by the invention]
(1) Gasification gas from garbage has been tried to be used as fuel for internal combustion engines such as gas turbines, diesel engines and gas engines, and fuel cells. However, the gasification gas of waste has a low calorific value (about 1000-2000 Kcal / m ³ N), and it is necessary to considerably improve the combustion device to be used in an internal combustion engine, so that it is difficult to use. In the case of fuel cells, the exhaust gas temperature is as low as about 400 ° C. in the case of an external reforming molten carbonate fuel cell or an internal reforming molten carbonate fuel cell using natural gas as fuel. The use of recovered energy is limited. In order to use the fuel in the internal reforming type molten carbonate fuel cell, it is necessary to consider the cooling method of the cell or the fuel processing.
(2) In the case of an internal reforming type molten carbonate fuel cell using natural gas as fuel, the power generation efficiency is as high as 47%, but the total efficiency including heat utilization is about 72%.
[0003]
[Means for Solving the Problems]
(1) Gasification gas (fuel gas) of garbage is pressurized with a compressor and then led to a methanation reactor and converted to methane-rich gas by a fixed bed catalytic reaction. This reaction is an exothermic reaction, and the fuel gas is heated by this reaction heat. Further, by using water for cooling the fuel gas to remove reaction heat, the fuel gas can be humidified with the generated steam. The methane-rich gas from the methanation reactor is supplied to the fuel cell, the cathode exhaust from the fuel cell is led to a heat exchanger, heat is exchanged with air pressurized by an air compressor or blower, and the air is preheated, The preheated air is led to the garbage drying zone of the garbage gasification facility and used directly for garbage drying. Thereby, it is not necessary to use the fuel cell cathode exhaust for preheating the fuel gas, so that the cathode exhaust temperature can be increased.
(2) The air preheated in (1) is led to the combustor, and after further raising the temperature, it is used for drying garbage.
(3) Garbage pyrolysis gasification gas (H ₂ , CO, CO ₂ ) is mixed with steam generated by the reaction heat of the methanation reactor, and then led to the methanation reactor to produce methane rich gas. Supplied to the anode via the internal reformer of the internal reforming type molten carbonate fuel cell, the anode exhaust is led to the catalytic oxidizer, the unreacted fuel is oxidized by air, and the catalytic oxidizer outlet gas is supplied to the cathode Then, electricity is generated, and the cathode exhaust from the fuel cell is led to a waste gasification facility and directly used for drying the waste.
(4) Waste pyrolysis gasification gas (H ₂ , CO, CO ₂ ) is mixed with the vapor generated by the reaction heat of the methanation reactor, and then led to the methanation reactor to produce methane rich gas. Supplied to the anode via the internal reformer of the internal reforming type molten carbonate fuel cell, the anode exhaust is led to the catalytic oxidizer, the unreacted fuel is oxidized by air, and the catalytic oxidizer outlet gas is supplied to the cathode Then, the cathode exhaust from the fuel cell is led to a heat exchanger, heat is exchanged with air pressurized by an air compressor or a blower to preheat the air, and the preheated air is used as a gasification furnace for waste. To oxidizer for gasification of garbage.
[0004]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an internal reforming molten carbonate fuel cell power generation system using pyrolysis gasification gas of garbage (hereinafter referred to as garbage gasification gas) . Gasification gas (fuel gas) generation part of garbage shows an example of pyrolysis gasification equipment of garbage and is not directly the object of the present invention, and exhaust from the fuel cell is combustion gas and has special characteristics Therefore, the description of the waste gasification facility and the fuel cell portion is basically omitted, and the waste gasification gas treatment portion and the fuel cell exhaust use portion will be described below.
The gasification gas (the main components are H ₂ , CO, CO ₂ ), which is pyrolyzed and gasified in the gasification melting furnace 1, is cleaned in the gas cleaning tower 2, purified by the gas purification device 3, and further filtered by the filter 4 After the particulate matter is removed, it is sent to the fuel gas compressor 5 and compressed to about 3 data. This fuel gas F is mixed with a part of the steam S from the brackish water separator 21 mounted on the upper part of the methanation reactor to suppress carbon deposition and is required for the reforming reaction downstream, and methanation It is sent to the reactor 6. In the methanation reactor, high-temperature methane-rich gas M is generated in the fixed bed by the Ni-based catalytic reaction of the fuel gas. This reaction is a strongly exothermic reaction and is cooled by the treated water W ′. The treated water evaporates to become steam S, and as described above, a part is sent to the methanation reactor, and the rest is used as surplus steam for another purpose. FIG. 2 shows the structure of the methanation reactor. The methane rich gas is further heated by the cathode exhaust E in the fuel superheater 8 and is reformed by the internal reformer 9 of the fuel cell, and then used for power generation. In the internal reforming type fuel cell, the heat absorption of the reforming reaction and the heat generation of the power generation reaction are offset, so that cooling from the outside is small. The cathode exhaust E discharged from the fuel superheater at about 600 ° C. is (a) directly introduced into the waste drying zone D of the waste gasification facility and used for drying the waste. (B) The air preheater 19 exchanges heat with the air pressurized by the air compressor 18 ′ or the air blower 18, and the preheated air H is guided to the waste gasification facility and used for drying the waste. (C) The preheated air of (b) is heated to a higher temperature by the combustor 20 and then guided to a waste gasification facility for use in drying the waste. (D) The preheated air of (b) is led to a waste gasification and melting furnace to be used as an oxidizer for waste gasification. In this figure, the air is preheated with the exhaust from the fuel cell in (c), heated to a higher temperature with a combustor, and then introduced into the waste gasification facility waste drying zone. The case where it uses for drying is shown.
[0005]
【The invention's effect】
(1) Conventionally, a practical system using waste gasification gas as fuel for an internal reforming molten carbonate fuel cell has not been generally known. By introducing the gasification gas from the waste to the methanation reactor and making it into methane-rich gas, it is possible to generate electricity in the internal reforming molten carbonate fuel cell.
(2) In the case of an external reforming type molten carbonate fuel cell or an internal reforming type molten carbonate fuel cell using natural gas as fuel, heat is taken up by preheating and humidification of the fuel. The use of recovered energy is limited because it is as low as about 0C. However, in the case of the present invention, fuel preheating and humidification are carried out in a methanation reactor, and the exhaust gas temperature is as high as about 600 ° C., so that it is possible to dry waste that requires a higher temperature by introducing it to a waste gasification facility. It can be used to heat oxidants for gasification of waste and effectively use energy.
[Brief description of the drawings]
1 is a flow diagram of a fuel cell power generation system using waste gasification gas according to the present invention. FIG. 2 is a structural diagram of a methanation reactor according to the present invention. FIG. 3 is a conventional fuel cell power generation using natural gas. System flow diagram [Fig. 4] Structure diagram of conventional fuel humidifier [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gasification melting furnace 2 Gas washing tower 3 Gas refiner 4 Filter 5 Fuel gas compressor 6 Methanation reactor 7 Pump 8 Fuel superheater 9 Internal reformer 10 Catalytic oxidizer 11 Water treatment device 12 Block valve 13 Check Valve 14 Water level control valve 15 Flow control valve 16 Pressure control valve 17 Safety valve 18 Air blower 18 'Air compressor 19 Air preheater 20 Combustor 21 Air / water separator 31 Fuel booster blower 32 Desulfurizer 33 Filter 34 Fuel humidifier 35 Pre Converter 36 Water treatment device 37 Treated water tank AR Air B Garbage E Cathode exhaust F Fuel FG Fuel gas H Preheated air M Methane rich gas N Natural gas O Oxidant (air, oxygen)
S Steam SG Slag PM Particulate W W Tap water W 'Treated water W "Wash water Ni Nickel-based catalyst MCFC Molten carbonate fuel cell A Anode C Cathode D Drying zone P Compression zone DC Downcomer T Heating tube SN Spray nozzle

Claims (4)

Waste pyrolysis gasification gas (H ₂ , CO, CO ₂ ) is mixed with steam generated by the reaction heat of the methanation reactor, then led to the methanation reactor to produce methane rich gas, which is internally reformed Is supplied to the anode via the internal reformer of the molten carbonate fuel cell, the anode exhaust is led to the catalytic oxidizer, the unreacted fuel is oxidized with air, and the catalytic oxidizer outlet gas is supplied to the cathode for power generation. Then, the cathode exhaust from the fuel cell is guided to a heat exchanger, and the air is preheated by exchanging heat with the air pressurized by an air compressor or blower, and the preheated air is removed from the garbage gasification facility. A power generation system that leads to the drying zone and is used to dry waste directly . The power generation system according to claim 1, wherein the air preheated by the heat exchanger is guided to a combustor and further heated to be used for drying garbage. Waste pyrolysis gasification gas (H ₂ , CO, CO ₂ ) is mixed with steam generated by the reaction heat of the methanation reactor, then led to the methanation reactor to produce methane rich gas, which is internally reformed Is supplied to the anode via the internal reformer of the molten carbonate fuel cell, the anode exhaust is led to the catalytic oxidizer, the unreacted fuel is oxidized with air, and the catalytic oxidizer outlet gas is supplied to the cathode for power generation. And a power generation system in which the cathode exhaust from the fuel cell is led to a waste gasification facility and directly used for drying the waste. Waste pyrolysis gasification gas (H ₂ , CO, CO ₂ ) is mixed with steam generated by the reaction heat of the methanation reactor, then led to the methanation reactor to produce methane rich gas, which is internally reformed Is supplied to the anode via the internal reformer of the molten carbonate fuel cell, the anode exhaust is led to the catalytic oxidizer, the unreacted fuel is oxidized with air, and the catalytic oxidizer outlet gas is supplied to the cathode for power generation. Then, the cathode exhaust from the fuel cell is led to a heat exchanger, heat is exchanged with air pressurized by an air compressor or a blower to preheat the air, and the preheated air is led to a garbage gasifier, A power generation system that uses oxidant for gasification of garbage.

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