JP2005228583A - Fuel cell power generation system and starting method of fuel cell power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell battery power generation system and a starting method of the fuel cell power generation system wherein a fuel cell as well as a fuel treatment device can be pre-heated to a prescribed operation temperature before starting power generation. <P>SOLUTION: This system is provided with a fuel cell 30; a storing device 71 to recover and store water as the recovered water 42a; the fuel processing device 7 having a reforming part 9 to form a reformed gas, a heat exchange part 12 which is formed at the circumference of the reforming part 9 and carries out the heat exchange, a heating part 8 to heat the reforming part 9, and a carbon monoxide reduction part 14 to form a fuel gas 3a; a water heating device 130 for preheating to carry out heat exchange between the recovered water 42a and water 24a for preheating to preheat the fuel cell 30; a recovered water circulation flow passage of the recovered water 42a from the storing device 71 to the heat exchange part 12, the water heating device 130 for preheating, and the storing device 71; and a water circulation flow passage for preheating the water 24a for preheating from the fuel cell 30 to the water heating device 130 for preheating and the fuel cell 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell power generation system and a fuel cell power generation system start-up method, and more particularly to a fuel cell that can preheat a fuel cell together with a fuel processing device to a predetermined temperature before the start of power generation and has a short start-up time. The present invention relates to a power generation system and a method for starting a fuel cell power generation system.

  Source gas such as city gas, LPG, digestion gas, methanol, GTL and kerosene is generated by a fuel processing device and is supplied to the fuel electrode of the fuel cell, and an oxidant gas containing oxygen such as air A fuel cell power generation system that generates electricity through an electrochemical reaction by supplying to the air electrode of a fuel cell, or a fuel cell cogeneration system that collects and supplies exhaust heat such as fuel cell power and fuel cell exhaust heat as heat energy In a generation system or the like, the time required to start power generation after the system is started or the time required to achieve rated power generation, that is, the system startup time is important for the economics and convenience of the system.

  In a conventional fuel cell power generation system, as a starting method of a fuel cell power generation system that requires a fuel processing device other than hydrogen gas as a raw material fuel to be used, for example, a reforming portion of the fuel processing device is set in a predetermined manner by burning raw material fuel Heat to temperature, then introduce raw material fuel into the reforming section to generate reformed gas, guide the generated reformed gas to the carbon monoxide reducing section and heat the carbon monoxide reducing section to reduce carbon monoxide The carbon monoxide reducing gas exiting the section is led to the combustion section as combustion fuel and burned, and the temperature of the carbon monoxide reducing section reaches a predetermined temperature and the carbon monoxide concentration of the carbon monoxide reducing gas sufficiently decreases Thereafter, the carbon monoxide reducing gas is supplied to the fuel cell as a fuel gas to start power generation, and the fuel cell is generally raised to a predetermined temperature by heat generation.

  However, in the conventional fuel cell power generation system and the method for starting the fuel cell power generation system, for example, if the flow rate of the reformed gas is increased in order to shorten the startup time, the flow rate of the carbon monoxide reduced gas increases, so that Since the amount of combustion increases and as a result, the temperature of the reforming section excessively rises and the reforming catalyst is deteriorated, the start-up time cannot be shortened sufficiently.

  Accordingly, the present invention provides a fuel cell power generation system and a fuel cell power generation system startup method that can preheat a fuel cell together with a fuel processing apparatus to a predetermined temperature before power generation starts, and that the startup time of the fuel cell system is short. For the purpose.

  In order to achieve the above object, the fuel cell power generation system according to the first aspect of the present invention generates water by generating an electrochemical reaction between the fuel gas 3a and the oxidant gas 61a, for example, as shown in FIG. A fuel cell 30 that performs recovery; a storage device 71 that recovers and stores the generated water as recovered water 42a; a raw material fuel 4a and recovered water 42a or air are supplied to reform the raw material fuel 4a, Reducing the carbon monoxide in the reformed gas, the heat exchanger 12 that is formed around the reformer 9 to exchange heat, the heating unit 8 that heats the reformer 9, and the reformed gas A fuel treatment device 7 having a carbon monoxide reduction unit 14 for generating fuel gas 3a; a preheating water heater 130 for exchanging heat between the recovered water 42a and the preheating water 24a for preheating the fuel cell 30; and a storage device 71, heat exchanger 12 and preheating water A recovery water circulation passage for the recovery water 42a leading to the storage device 71; a preheating water heater 130 leading from the fuel cell 30; and a preheating water circulation passage for the preheating water 24a leading to the fuel cell 30. It is configured.

  If comprised in this way, the heat exchange part, the preheating water heater from the storage device, the recovery water circulation flow path of the recovered water reaching the storage device, the preheating water heater from the fuel cell, and the preheating water reaching the fuel cell Since the reforming section is cooled by the recovered water and does not rise excessively, the recovered water that has passed through the heat exchanging section and the preheating water that preheats the fuel cell perform heat exchange. The fuel cell as well as the processing device can be preheated to a predetermined temperature before the start of power generation, and a fuel cell power generation system with a short startup time of the fuel cell system can be provided.

  Further, as described in claim 2, in the fuel cell power generation system according to claim 1, the oxidant gas humidifier is configured integrally with the storage device 71 and circulates the recovered water 42a to humidify the oxidant gas 61a. 70, a branching means 135 for branching the recovered water circulation flow path, and a flow path extending from the branching means 135 to the oxidant gas humidifier 70, disposed in the recovered water circulation flow path between the storage device 71 and the heat exchange unit 12. And a recovery water circulation channel closing means 133 that is disposed in the recovery water circulation channel between the branching unit 135 and the heat exchange unit 12 and closes the recovery water circulation channel.

  With this configuration, the oxidant gas humidifier is preheated together with the preheating of the fuel cell, so that it is possible to provide a fuel cell power generation system having a high power generation efficiency and a long life.

  Typically, the fuel cell power generation system includes a preheating water cooler 110 that performs heat exchange between the preheating water 24a and the refrigerant fluid 43a, and a hot water storage tank 120 that stores the refrigerant fluid 43a.

  If comprised in this way, the heat | fever generate | occur | produced when it generate | occur | produces with the fuel cell collect | recovered in the water for preheating will be stored in the waste heat warm water of a hot water storage tank, and it will become possible to utilize as a heat source. Further, since the temperature of the preheating water is prevented from rising above a predetermined temperature, the fuel cell is maintained at an appropriate temperature by the preheating water.

  Further, as described in claim 3, in the fuel cell power generation system according to claim 2, the reforming unit 9 is heated, and the reforming unit 9 has a first temperature (for example, circulating water / When the recovered water circulation start temperature T1) is reached, the preheating water 24a is circulated through the preheating water circulation flow path, the recovered water 42a is circulated through the recovered water circulation flow path to heat the preheating water 24a, and the preheating water heater 130 and The temperature of the preheating water 24a to the fuel cell 30 is the second temperature (for example, the recovered water circulation stop temperature T2 based on the circulating water temperature described in FIG. 2), or the temperature of the carbon monoxide reducing unit 14 is the third temperature. You may comprise so that the control apparatus 18 which closes the collection | recovery water circulation flow path closing means 133 may be provided when it becomes temperature (for example, carbon monoxide reduction part reaction suitable temperature T3 demonstrated in FIG. 2).

  The first temperature (for example, circulating water / recovered water circulation start temperature T1 described in FIG. 2) is preferably about 500 ° C. to 800 ° C., more preferably about 600 ° C. to 750 ° C. The second temperature (for example, the recovered water circulation stop temperature T2 based on the circulating water temperature described in FIG. 2) is preferably about 40 ° C. to 90 ° C., more preferably about 50 ° C. to 80 ° C. The third temperature (for example, the carbon monoxide reducing portion reaction suitable temperature T3 described in FIG. 2) is preferably about 180 ° C. to 500 ° C., more preferably about 200 ° C. to 350 ° C.

  With this configuration, each part is controlled based on the temperature by the control device, so that a human error can be quickly and reliably eliminated with the human error, and the fuel cell and the fuel processing device are also It is possible to provide a fuel cell power generation system that can be preheated to a temperature and has a short startup time of the fuel cell system.

  In order to achieve the above object, a fuel cell power generation system start-up method according to a fourth aspect of the present invention provides a raw material fuel 4a and water 42a or air as shown in FIG. A reforming section preheating step (S102) for reforming the fuel 4a and heating the reforming section 9 that generates reformed gas; and the reforming section 9 has a first temperature (for example, circulating water / recovered water circulation start temperature T1). ), The first heat exchanging step (S202) for exchanging heat between the reformed gas and the first medium 42a; and the first exchanging heat between the first medium 42a and the second medium 24a. A second heat exchange step (S203); a fuel cell preheating step (S204) in which the second medium 24a heats the fuel cell 30 that generates electricity by an electrochemical reaction between the fuel gas 3a and the oxidant gas 61a; The medium 24a has a second temperature (recovered water circulation based on the circulating water temperature). The temperature of the carbon monoxide reduction unit 14 that generates carbon monoxide reduction gas as the fuel gas 3a by reducing the carbon monoxide in the reformed gas is the third temperature (carbon monoxide reduction unit reaction). A first heat exchange stop step (S207) for stopping the heat exchange between the reformed gas and the first medium 42a when the preferred temperature T3) is reached; and the first medium 42a and the second medium 24a A second heat exchange stopping step (S208) for stopping the heat exchange.

  With this configuration, the heat exchange between the reformed gas and the first medium, the heat exchange between the first medium and the second medium, and the second medium heat the fuel cell. In addition to the processing device, the fuel cell can be preheated to a predetermined temperature before the start of power generation, and a startup method of the fuel cell power generation system with a short startup time of the fuel cell system can be provided.

  As described above, according to the present invention, a fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas to generate water; a storage device that recovers and stores the generated water as recovered water; A reforming unit that reforms the raw material fuel by supplying fuel and recovered water or air to generate reformed gas, a heat exchange unit that is formed around the reforming unit 9 and exchanges heat, A fuel treatment device having a heating part for heating the heating part, and a carbon monoxide reduction part for reducing the carbon monoxide in the reformed gas to generate a fuel gas; and a preheating water for preheating the recovered water and the fuel cell A preheating water heater for performing heat exchange; a storage device, a heat exchanging unit, a preheating water heater, a recovered water circulation channel for recovered water reaching the storage device; a fuel cell, a preheating water heater, and a fuel cell The preheating water circulation path that leads to the Since the heat of the heating section and the recovered water that has passed through the heat exchange section and the preheating water that preheats the fuel cell exchange heat without excessive rise, the fuel cell together with the fuel processing device has a predetermined temperature before the start of power generation. Therefore, it is possible to provide a fuel cell power generation system that can be preheated to a short time and that has a short startup time.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the symbols with “a” and “42A”, “42B”, and “42C” represent objects, and when indicated by these symbols, the line indicates the flow of the object, and these symbols are appended. Lines represent piping when not indicated by a symbol. A broken line represents an electric signal.

  FIG. 1 is a schematic block diagram of a fuel cell power generation system 1 according to an embodiment of the present invention. The fuel cell power generation system 1 generates power by an electrochemical reaction between the fuel gas 3a and the oxidant gas 61a, and serves as a fuel cell 30 that generates water, and a storage device that recovers and stores the generated water as recovered water 42a. Preheating the liquid storage unit 71, the fuel treatment device 7 that generates the hydrogen-rich fuel gas 3a from the raw material fuel 4a such as city gas, LPG, digestion gas, methanol, GTL, and kerosene, the recovered water 42a, and the fuel cell 30 A circulating water heater 130 as a preheating water heater for exchanging heat with the circulating water 24a as the preheating water, and a jacket 12 and a circulating water heater 130 as a heat exchange section of the fuel processing device 7 from the liquid storage section 71. And a circulating water circulation channel as a preheating water circulation channel for preheating water from the fuel cell 30 to the circulating water heater 130 and the fuel cell 30. And a flow path.

  The fuel processing device 7 supplies the raw material fuel 4a and the recovered water 42a to reform the raw material fuel 4a, generates reformed gas, and heat exchange formed around the reforming unit 9. A jacket 12 as a heat exchanging part, a combustion part 8 as a heating part for heating the reforming part 9, and a carbon monoxide reducing part for reducing the carbon monoxide in the reformed gas to generate the fuel gas 3a 14, and further includes a raw material fuel supply unit (not shown) and a combustion air supply unit.

  Further, the fuel cell power generation system 1 is configured integrally with the liquid storage unit 71, and includes an oxidant gas humidifier 70 that circulates the recovered water 42 a and humidifies the oxidant gas 61 a, and the liquid storage unit 71 and the jacket 12. A branch pipe 135 that is disposed in the recovered water circulation channel between the branch pipe 135 as a branching means for branching the recovered water circulation channel, and a recovered water branch channel 41 as a channel from the branch pipe 135 to the oxidant gas humidifier 70. A recovery water closing valve 133 is provided as a recovery water circulation channel closing means that is disposed in the recovery water circulation channel between the branch pipe 135 and the jacket 12 and closes the recovery water circulation channel. Typically, the oxidant gas humidifier 70 and the liquid storage part 71 constitute a gas-liquid contact tower 170 integrally.

  Still further, the fuel cell power generation system 1 is introduced from a combustion gas heat exchanger 83 that performs heat exchange between the recovered water 42a and the combustion gas, a fuel gas 3a introduced from the fuel processing device 7, and a gas-liquid contact tower 170. A fuel gas heat exchanger 114 that exchanges heat between the three fluids of the oxidant gas 61a and the circulating water 24a that circulates in the circulating water circulation channel, the circulating water cooler 110 that cools the circulating water 24a, and the circulating water cooler 110. A hot water storage tank 120 for storing the exhaust heat hot water 43a that exchanges heat with the circulating water 24a, a control unit 18 that controls each part of the fuel cell power generation system 1, gas-liquid separators 45, 55, and 89, , A blower 84, pumps 82, 85, 108 and 125, and water treatment devices 86 and 93. Furthermore, a three-way valve for switching the flow path of the fuel gas 3a to the flow path leading to the combustion section 8 is provided in the flow path for introducing the fuel gas 3a from the carbon monoxide reduction section 14 to the fuel gas heat exchanger 114. 13.

  The raw material fuel supply unit (not shown) of the fuel processing device 7 is configured to quantitatively supply raw material fuel 4a such as city gas, LPG, digestion gas, methanol, GTL, and kerosene. A tank for storing the raw material fuel 4a may be provided, or the raw material fuel 4a may be introduced from outside the system. When the pressure of the gas at the supply source is kept high, such as city gas or LPG, a flow control valve is provided. When the pressure at the supply source is not high, a blower is provided to secure a pressure for supplying the raw material fuel into the reforming unit 9. Further, when the raw material fuel 4a is liquid like GTL or kerosene, a metering pump may be provided, or a pump and a flow rate adjusting valve that do not have a flow rate adjusting function may be provided.

  The combustion air supply unit (not shown) is a device that supplies oxygen consumed by combustion in the combustion unit 8. It may be configured to send the atmosphere as combustion air 5a by a blower, and it is preferable to have a filter for preventing contamination of suspended matters in the atmosphere. It is also preferable to have a flow rate adjustment valve for adjusting the supply amount of the combustion air 5a. In the following description, unless otherwise specified, “connected” means that the two devices and the like are “connected”, including the case where they are directly connected and the case where they are connected via piping.

  The combustion unit 8 is a fuel gas 3a as a carbon monoxide reduction gas generated by the raw material fuel 4a and the carbon monoxide reduction unit 14, and the carbon monoxide reduction unit without sufficiently reducing the carbon monoxide in the gas. Combustion gas 3 a ′ delivered from 14 or anode off gas 21 a which is an off-gas of the anode electrode of fuel cell 30 to be described later is burned together with combustion air 5 a to heat reforming section 9. In preparation for when the raw material fuel 4a is a liquid such as kerosene, it preferably has a vaporizer. It has a burner nozzle that can be used for various fuels such as kerosene, city gas, LPG and other raw material fuel 4a, combustion gas 3a 'delivered from the carbon monoxide reduction unit 14, or anode offgas 21a. Or you may have a different burner nozzle, respectively. Since it is a device for heating the reforming unit 9, it is preferably formed integrally with the reforming unit 9, disposed in the center of the reforming unit 9, and combusted in the combustion unit 8, thereby surrounding reforming units 9. The high temperature gas combusted in the combustion unit 8 may flow around the reforming unit 9 to heat the reforming unit 9, and any configuration as long as the reforming unit 9 is heated can be used. It may be.

  The combustion section 8 typically burns the combustion gas 3a ′ delivered from the raw material fuel 4a or the carbon monoxide reduction section 14 together with the combustion air 5a at the time of start-up, and the anode offgas 21a as the fuel during rated operation. The reforming unit 9 is heated by burning together with the combustion air 5a. The combustion gas 6 a that is the exhaust gas after burning in the combustion unit 8 is introduced into the combustion gas heat exchanger 83 described later via the pipe 37. Further, the supply of the fuel gas 3 a to the fuel cell 30 and the supply of the combustion gas 3 a ′ to the combustion unit 8 are appropriately switched by the three-way valve 13.

  The three-way valve 13 has a single inlet and two outlets and switches the flow path, and is configured to operate by a solenoid or a motor drive. The three-way valve 13 is wired with a signal cable for transmitting a control signal i1 transmitted from a control unit 18 to be described later, and the three-way valve 13 is configured to receive the control signal i1 and operate. The means for switching may be configured by a combination of a branch pipe and a gate valve instead of a three-way valve. However, when the three-way valve is used, the fuel cell power generation system 1 can be downsized without taking up space. .

  The reforming unit 9 includes a reforming catalyst packed bed (not shown) filled with a reforming catalyst (not shown), and reforming rich in hydrogen by a reforming reaction from the raw fuel 4a and the recovered water 42a. It is configured to generate gas. The reforming reaction is a reaction in which hydrogen, carbon dioxide, and carbon monoxide are generated from hydrocarbon and moisture in the raw material fuel 4a by a reforming catalyst at a high temperature. The reforming reaction is an endothermic reaction, and it is necessary to supply heat from the outside for the reforming reaction. The reforming section 9 is preferably formed in a substantially cylindrical shape containing the reforming catalyst, in terms of strength and production. However, in order to maintain a high temperature, it is preferable that the combustion section 8 is disposed substantially coaxially within the interior.

  Any reforming catalyst (not shown) may be used as long as it promotes the reforming reaction. For example, a Ni-based reforming catalyst or a Ru-based reforming catalyst is used as the type of catalyst. In addition, the shape of the reforming catalyst is preferably a granular shape, a cylindrical shape, a honeycomb shape, or a monolith shape in order to perform the reaction efficiently.

  The jacket 12 is formed around the reforming unit 9. The jacket 12 has a structure in which the recovered water 42a circulating in the recovered water circulation passage flows in a space defined by the reforming section 9 and a partition wall disposed around the reforming section 9, It is configured to cool by allowing the heat to be transferred. That is, the jacket 12 becomes the reforming unit 9, typically a heat exchange unit between the reformed gas and the recovered water 42a. By using the heat exchange part between the reforming part 9 and the recovered water 42a as a jacket, the manufacture becomes easy and an increase in pressure loss of the recovered water 42a can be prevented. However, the heat exchange unit between the reforming unit 9 and the recovered water 42 a is not a jacket, and a pipe through which the recovered water 42 a flows may be inserted into the reforming unit 9. With this configuration, the temperature distribution of the reforming catalyst tends to be uniform. The reforming unit 9 is prevented from being heated excessively by exchanging heat with the circulating recovered water 42a, and the temperature of the circulating recovered water 42a rises.

  The carbon monoxide reduction unit 14 is configured to reduce the carbon monoxide in the reformed gas and generate the fuel gas 3a. The carbon monoxide reduction unit 14 typically includes a shift unit 10 having a shift catalyst packed bed (not shown) filled with a shift catalyst that converts carbon monoxide in the reformed gas, and the reformed gas in the reformed gas. And a selective oxidation unit 11 having a selective oxidation catalyst packed layer (not shown) filled with a selective oxidation catalyst for removing the carbon monoxide.

  The shift unit 10 is configured to decompose carbon monoxide in the reformed gas into carbon dioxide and hydrogen by a shift reaction with moisture in the reformed gas as a front stage of the carbon monoxide reducing unit 14. . The modification reaction is an exothermic reaction. If the reaction temperature is lowered, the carbon monoxide concentration after modification is lowered, but the reaction rate is lowered.

  As the shift catalyst, typically, an iron Fe-chromium Cr-based high-temperature shift catalyst, a platinum Pt-based medium-high-temperature shift catalyst, a copper Cu-zinc Zn-based low-temperature shift catalyst, or the like is used. The metamorphic portion 10 typically has a generally cylindrical shape as a whole. Examples of the shape of the catalyst include a granular shape, a columnar shape, a honeycomb shape, and a monolith shape. Here, a gas in which carbon monoxide in the reformed gas is reduced by the shift unit 10 is referred to as a shift gas unless otherwise specified.

  The selective oxidation unit 11 is used as a rear stage of the carbon monoxide reduction unit 14 to further reduce and remove carbon monoxide in the shift gas by a carbon monoxide selective oxidation reaction with oxygen in the air supplied from the outside. It is configured. When a polymer electrolyte fuel cell is used as the fuel cell 30, the platinum Pt catalyst of the anode electrode (fuel electrode) 32 is poisoned by the carbon monoxide in the fuel gas 3a, resulting in a decrease in power generation efficiency. is there. Therefore, carbon monoxide is oxidized to carbon dioxide using a selective oxidation catalyst having high selective oxidizability for carbon monoxide.

  The selective oxidation catalyst is not particularly limited as long as it has a high selective oxidation property with respect to carbon monoxide. For example, a Pt-based selective oxidation catalyst, a Ru-based selective oxidation catalyst, a Pt-Ru-based selective oxidation catalyst, or the like is used. Examples of the shape of the catalyst include a granular shape, a cylindrical shape, a honeycomb shape, and a monolith shape. Here, the selective oxidation gas obtained by further reducing / removing carbon monoxide in the conversion gas by the conversion gas and the selective oxidation unit 11 is referred to as a carbon monoxide reduction gas in a broad sense unless otherwise specified. It is used as fuel gas 3a for the fuel cell 30 or the like.

  In the present embodiment, the fuel processor 7 includes the shift unit 10 and the selective oxidation unit 11 to reduce carbon monoxide. However, the carbon monoxide may be configured to include only one of them. It is sufficient if the concentration is reduced. However, by providing the shift conversion unit 10 and the selective oxidation unit 11, the concentration of carbon monoxide is reduced in the shift conversion unit 10, and the hydrogen concentration as fuel is increased. This is preferable because the concentration can be lowered sufficiently.

  The reforming unit 9 and the shift unit 10 are provided with a reforming unit temperature detector 15 and a shift unit temperature detector 16 for detecting the internal temperature, respectively. For example, a thermocouple, a thermistor, an infrared thermometer, or the like is used as the reforming unit temperature detector 15 and the transformation unit temperature detector 16. The reforming unit temperature detector 15 and the transformation unit temperature detector 16 are wired with signal cables that transmit the detected temperatures to the control unit 18 as the reforming unit temperature signal i2 and the transformation unit temperature signal i3, respectively. The temperature detector 15 and the shift section temperature detector 16 are configured to transmit the reforming section temperature signal i2 and the shift section temperature signal i3 to the control section 18.

  The fuel gas 3a generated by the fuel processing device 7 is introduced into the fuel gas heat exchanger 114 via a pipe 38 connecting the selective oxidation unit 11 and a fuel gas heat exchanger 114 described later, and the next stage fuel cell. 30 fuel gas 3a is supplied. The three-way valve 13 described above is disposed on the pipe 38.

  As the fuel cell 30, for example, a stacked polymer electrolyte fuel cell can be used, and has a circulating water flow path 31, a fuel electrode 32, and an air electrode 33. A nozzle (not shown) for introducing the fuel gas 3a generated by the fuel processing device 7 and supplied via the fuel gas heat exchanger 114 and an anode offgas 21a that is an offgas of the fuel gas 3a are discharged to the fuel electrode 32. A nozzle (not shown) is arranged. A nozzle (not shown) for introducing an oxidant gas 61a sent from the gas-liquid contact tower 170 via the fuel gas heat exchanger 114 and a cathode offgas 22a which is an offgas of the oxidant gas 61a are discharged to the air electrode 33. A nozzle (not shown) is arranged. A nozzle (not shown) for introducing the circulating water 24a pumped from the pump 108 and supplied via the fuel gas heat exchanger 114 and a nozzle (not shown) for discharging the circulating water 24a are arranged in the circulating water flow path 31. Is done. The fuel cell 30 is connected to each part by connecting piping to each nozzle (not shown).

  The fuel cell 30 outputs electric power by the electrochemical reaction between the fuel gas 3a and the oxidant gas 61a to generate water. This electrochemical reaction is an exothermic reaction, and circulating water 24a is introduced for cooling.

  When a polymer electrolyte fuel cell is used, the oxidant supplied to the fuel electrode 3a and the air electrode 33 is supplied to the fuel electrode 32 in order to maintain high electrical conductivity of the proton exchange membrane (not shown). It is necessary to humidify the gas 61a to a predetermined dew point. The required dew point of the fuel gas 3a is generally in the range of 50 to 80 ° C., depending on the operating conditions such as the operating temperature of the fuel cell to be used, and the required dew point of the oxidant gas 61a is 50 to 50 ° C. Generally, it is in the range of 80 ° C.

  The circulating water flow path 31 of the fuel cell 30 is configured so that the circulating water 24a flows. As described above, the anode off-gas 21a discharged from the fuel electrode 32 of the fuel cell 30 is introduced into the combustion unit 8 and used as combustion fuel during rated operation. The cathode off-gas 22a discharged from the air electrode 33 of the fuel cell 30 and the combustion gas 6a discharged from the fuel processing device 7 are mixed to form a mixed gas 63a as a heating gas, and combustion gas heat exchange is performed via the pipe 37. Introduced into the vessel 83.

  The combustion gas heat exchanger 83 is configured to exchange a part of sensible heat and latent heat between the gas that is the mixed gas 63a and the liquid that is the recovered water 42a, and a plate heat exchanger is preferable. Used. Alternatively, a multitubular heat exchanger is preferably used. More preferably, a multitubular heat exchanger having fins in the flow path of the mixed gas 63a is used. The temperature of the recovered water 42a is increased by heat exchange between the mixed gas 63a and the recovered water 42a in the combustion gas heat exchanger 83.

  From the outlet of the mixed gas 63 a of the combustion gas heat exchanger 83, a pipe 40 is connected to the outside of the system 102 through the gas-liquid separator 89, and moisture is recovered by the gas-liquid separator 89. The remaining exhaust gas 64 a from which moisture has been recovered from the mixed gas 63 a by the gas-liquid separator 89 is discharged to the outside of the system 102 through the pipe 40.

  The gas-liquid separator 89 separates the mixed gas 63a and the condensed water contained in the mixed gas 63a, and the separated water is sent to the liquid storage unit 71 of the gas-liquid contact tower 170 as recovered water 42C. The liquid storage unit 71 stores the recovered water 42a.

  Here, by adding a cooler 100 connected to the upstream side of the gas-liquid separator 89 on the downstream side of the combustion gas heat exchanger 83 (illustrated by a one-dot chain line arrow), the exhaust gas 64a is discharged to the outside of the system 102. Further, the heat and moisture of the mixed gas 63a can be recovered.

  At the tip of the circulating water flow path 31, the circulating water heater 130 that performs heat exchange between the recovered water 42a and the circulating water 24a, the circulating water 24a, and the refrigerant in order from a nozzle (not shown) that flows out the circulating water 24a of the fuel cell 30. It is connected to the circulating water flow path 31 again via a circulating water cooler 110 that performs heat exchange with a fluid, typically a refrigerant fluid that recovers heat, a pump 108, and a fuel gas heat exchanger 114. In this way, a circulating water circulation path of the circulating water 42a that circulates from the circulating water flow path 31 to the circulating water flow path 31 through the circulating water heater 130, the circulating water cooler 110, the pump 108, and the fuel gas heat exchanger 114 is configured. .

  The circulating water heater 130 is configured to perform heat exchange between the recovered water 42a and the circulating water 24a whose temperature has been increased by exchanging heat with the reforming unit 9 using the jacket 12 of the reforming unit 9 at the time of startup. In order to exchange heat between liquids having a relatively small temperature difference, a plate heat exchanger is preferably used. Alternatively, a multitubular heat exchanger is preferably used. The temperature of the circulating water 24a is increased by exchanging heat with the recovered water 42a by the circulating water heater 130. At the time of start-up, the fuel cell 30 is configured to be preheated to a predetermined temperature by the circulating water 24a whose temperature has been increased by the circulating water heater 130.

  The circulating water cooler 110 is a heat exchanger for exchanging heat between the exhaust hot water 43a as the refrigerant fluid stored in the hot water storage tank 120 and pressurized and sent out by the pump 125, and the circulating water 24a. A plate-type heat exchanger is preferably used in order to exchange heat between relatively small liquids. The circulating water cooler 110 heats the exhaust heat hot water 43a and cools the circulating water 24a. That is, the exhaust heat in the circulating water 24a is recovered by the exhaust heat hot water 43a. Thereby, the circulating water 24a is maintained at a predetermined temperature during rated operation. The outlet nozzle (not shown) of the exhaust hot water 43a of the circulating water cooler 110 is connected to the hot water storage tank 120, and the exhaust heat hot water 43a collects the exhaust heat and is stored in the hot water storage tank 120. The heat is stored in the hot water storage tank 120 as recovered heat. That is, the exhaust heat hot water 43 a circulates between the pump 125, the hot water storage tank 120, and the circulating water cooler 110.

  A signal cable for transmitting a pump control signal i4 transmitted from the control unit 18 is wired to the pump 125. The pump 125 receives the pump control signal i4 and supplies the exhaust heat hot water 43a to the circulating water cooler 110. It is configured to start and stop circulation.

  The hot water storage tank 120 is connected to a device (not shown) that supplies heat to the heat demand outside the system by supplying or circulating the exhaust hot water 43a. For example, the waste heat hot water 43 a stored in the hot water storage tank 120 circulates outside the system and supplies the exhaust heat, and then is returned to the hot water storage tank 120. That is, the exhaust heat recovered in the exhaust heat hot water 43a is effectively used as a heat source.

  Typically, during rated operation, the pump 125 is operated to circulate the exhaust heat hot water 43a, and the circulating water 24a whose temperature has been lowered by the circulating water cooler 110 causes the electric power between the fuel gas 3a and the oxidant gas 61a. The fuel cell 30 is cooled by absorbing heat generated by a chemical reaction.

  That is, in the fuel cell power generation system 1, the circulating water 24a preheats the fuel cell 30 to a predetermined temperature by the circulating water 24a whose temperature has been increased by the circulating water heater 130 at the time of startup, and the fuel cell 30 has a certain amount. During the rated operation for generating the electric power, the fuel cell 30 is cooled by absorbing the heat generated by the electrochemical reaction between the fuel gas 3a and the oxidant gas 61a.

  The pump 108 pumps and circulates the circulating water 24a, and may be arranged on the path of the circulating water 24a that circulates, not between the circulating water cooler 110 and the fuel gas heat exchanger 114. . The pump 108 is wired with a signal cable for transmitting a pump control signal i8 transmitted from the control unit 18, and the pump 108 receives the pump control signal i8 and starts circulating the circulating water 24a in the circulating water circulation passage. Configured to stop.

  The fuel gas heat exchanger 114 exchanges heat between the circulating water 24a discharged from the circulating water passage 31 of the fuel cell 30 and the oxidant gas 61a delivered from the gas-liquid contact device 170, and further, the circulating water 24a, A three-fluid heat exchanger for exchanging heat with the fuel gas 3a delivered from the fuel processing device 7 is preferably used. More preferably, a multi-tube heat exchanger including a pipe provided with fins in the flow path between the oxidizing gas 61a, which is a gas, and the fuel gas 3a is used. Alternatively, a triple tube heat exchanger is also preferably used. In the fuel gas heat exchanger 114, the fuel gas 3a is cooled by the circulating water 24a, and the oxidant gas 61a is also cooled by the circulating water 24a.

  An outlet nozzle (not shown) of the fuel gas 3 a of the fuel gas heat exchanger 114 is connected to the fuel electrode 32 of the fuel cell 30 via the gas-liquid separator 45. The outlet nozzle (not shown) of the oxidant gas 61 a of the fuel gas heat exchanger 114 is connected to the air electrode 33 of the fuel cell 30 via the gas-liquid separator 55. An outlet nozzle (not shown) of the circulating water 24 a of the fuel gas heat exchanger 114 is connected to the circulating water passage 31 of the fuel cell 30.

  A circulating water temperature detector 17 that detects the temperature of the circulating water 24 a between the circulating water cooler 110 and the fuel cell 30 is disposed in the circulating water circulation passage between the circulating water cooler 110 and the pump 108. ing. The circulating water temperature detector 17 has the same configuration as the reforming unit temperature detector 15 and the like, and is wired with a signal cable for transmitting the detected temperature as the circulating water temperature signal i5 to the control unit 18, and the circulating water temperature signal i5. Is transmitted to the control unit 18.

  The gas-liquid separator 45 is a device that separates moisture in the fuel gas 3a cooled by the fuel gas heat exchanger 114, and is connected to a pipe for introducing the separated water into the gas-liquid contact tower 170 as recovered water 42A. The The gas-liquid separator 55 is a device that separates moisture in the oxidant gas 61a delivered from the gas-liquid contact tower 170 by the blower 84, and is a pipe that introduces the separated water into the gas-liquid contact tower 170 as recovered water 42B. Is connected. A pipe to be introduced into the gas-liquid contact tower 170 as the recovered water 42A is connected. Both the recovered water 42A and the recovered water 42B are sent to the liquid storage part 71 of the gas-liquid contact tower 170 and stored as recovered water 42a in the liquid storage part 71 in the same manner as the recovery water 42C described above.

  The gas-liquid contact tower 170 includes an oxidant gas humidifier 70 that circulates the recovered water 42a to humidify the oxidant gas 61a and a liquid storage unit 71 that stores the recovered water 42a.

  The gas-liquid contact tower 170 has a recovery water inlet 73 into which the recovered water 42A, 42B, 42C sent from the gas-liquid separators 45, 55, 89 are introduced, and the recovered water 42A, 42B, Liquid storage unit 71 storing 42C as recovered water 42a, recovered water suction port 74 through which recovered water 42a is sucked outward by pumps 82 and 85, and recovered water 42a exceeding a predetermined water level overflow. The overflow pipe 75 flows in, and the overflow port 76 into which the recovered water 42 a flows into the overflow pipe 75 flows. The oxidant gas inlet 72 into which the oxidant gas 61 a enters is located above the overflow port 76. The predetermined water level is a water level at which the overflow port 76 is set. The recovered water 42a flows out of the system of the gas-liquid contact tower 170 from the overflow pipe 75. Note that the oxidant gas inlet 72 exemplified in this embodiment is open to the atmosphere, and air in the atmosphere is used as the oxidant gas 61a.

  The gas-liquid contact tower 170 is led from the oxidant gas outlet 77 through which the oxidant gas 61 a flows out toward the fuel gas heat exchanger 114 and the liquid storage unit 71, and circulates through the combustion gas heat exchanger 83. A recovered water inlet 78 into which the recovered water 42a having been heated is injected, and a water disperser 79 that scatters the recovered water 42a injected into the recovered water inlet 78 into the gas-liquid contact tower 170 as fine water droplets. An oxidant gas humidifier 70 is provided. In addition, a demister 91 is provided between the water disperser 79 and the oxidant gas outlet 77 disposed in the upper part. The mist accompanying the rising oxidant gas 61a is removed by the demister 91.

  The gas-liquid contact tower 170 includes a filling unit 80 filled with a filling for promoting gas-liquid contact between the injected recovered water 42a and the oxidant gas 61a between an upper part and a lower part, and a filling part 80. And a filling support plate 81 for supporting.

  A blower 84 that pumps the oxidant gas 61 a to the fuel cell 30 is connected to the oxidant gas outlet 77 of the gas-liquid contact tower 170. The oxidant gas 61 a in the gas-liquid contact tower 170 is sucked by the blower 84. The oxidant gas 61a sucked from the oxidant gas inlet 72 and the recovered water 42a injected from the recovered water injection port 78 are brought into countercurrent contact at the filling unit 80, whereby the temperature of the oxidant gas 61a is increased. The recovered water 42a is washed and the temperature is raised and humidified. The outlet of the blower 84 is connected to the fuel gas heat exchanger 114, and the oxidant gas 61 a led out from the oxidant gas outlet 77 is supplied to the fuel gas heat exchanger 114.

  During the rated operation, the oxidant gas 61a that has been saturated or close to water vapor in the gas-liquid contact tower 170 is cooled by the circulating water 24a in the fuel gas heat exchanger 114, resulting in a decrease in temperature and an increase in relative humidity. It will be. Similarly, when the fuel gas 3a is derived from the fuel processing device 7, it is in a high temperature and high humidity state, and is cooled by the circulating water 24a in the fuel gas heat exchanger 114. As a result, the temperature Will decrease and the relative humidity will increase. That is, the oxidant gas 61a and the fuel gas 3a are saturated with water vapor or close to it. When the fuel gas 3a and the oxidant gas 61a having such a high relative humidity (wet) are supplied to the fuel cell 30, the solid polymer film of the fuel cell 30 has a decrease in power generation efficiency due to an increase in electrical resistance. In addition, there is no possibility that the solid polymer film is damaged and its life is shortened.

  As a result of the pressure increase of the oxidant gas 61a by the blower 84, the dew point of the oxidant gas 61a increases. For example, when the pressure increase of the oxidant gas 61a by the blower 84 is 12 kPa and the dew point of the oxidant gas 61a at the oxidant gas outlet 77 is 50 ° C., the dew point of the oxidant gas 61a is increased by about 2 ° C. and about 52 ° C. become. Therefore, when the dew point to be achieved by the oxidant gas 61a is constant, the humidifying load of the gas-liquid contact tower 170 is reduced by arranging the blower 84 of the oxidant gas 61a downstream of the gas-liquid contact tower 170, The gas-liquid contact tower 170 can be made compact. Unlike the case where the blower 84 is disposed on the oxidant gas inlet 72 side, the inside of the gas-liquid contact tower 170 is not pressurized by the blower 84.

  Further, since the liquid storage unit 71 in the gas-liquid contact tower 170 is in an atmospheric pressure state by maintaining the open state to the atmosphere at the oxidant gas inlet 72, the level with the gas-liquid separators 45, 55, 89 is reached. Due to the difference, the recovered water 42A, 42B, 42C can be introduced from the gas-liquid separators 45, 55, 89 into the liquid storage unit 71. Therefore, a liquid feed pump for feeding the recovered water 42A, 42B, and 42C can be eliminated. Further, the surplus recovered water 42a can be discharged from the bottom discharge port of the overflow pipe 75 disposed in the liquid storage unit 71 without using an extra-system discharge device such as an additional liquid feed pump or a liquid level sensor. There is also an advantage that it can be discharged out of the system.

  The recovered water 42a stored in the liquid storage part 71 of the gas-liquid contact tower 170 is decarboxylated by the oxidant gas 61a and cooled. A small amount of carbon dioxide gas is mixed into the oxidant gas 61a by the decarbonation process of the recovered water 42a. However, since the carbon dioxide gas has almost no catalyst poisoning action on the air electrode catalyst in the fuel cell 30, the fuel cell 30 is deteriorated. There is no effect on life.

  The recovered water suction port 74 of the gas-liquid contact tower 170 is connected in order from the recovered water suction port 74 through the pump 82, the water treatment device 93 described later, the jacket 12 of the fuel treatment device 7, and the circulating water heater 130. It is connected to the recovered water inlet 78 at the top of the liquid contact tower 170. As described above, the liquid storage unit 71 passes through the recovered water suction port 74, the pump 82, the water treatment device 93, the jacket 12 of the fuel processing device 7, the recovered water injection port 78, the water disperser 79, and the filling unit 80. A recovered water circulation flow path for recovered water 42a circulating to 71 is formed. The recovered water 42a decarboxylated and cooled in the gas-liquid contact tower 170 circulates in the recovered water circulation channel.

  Further, the recovered water circulation channel between the water treatment device 93 and the jacket 12 is closed in order from the water treatment device 93 side, the branch pipe 135 that branches the recovered water circulation channel, and the recovered water circulation channel is closed. A recovered water closing valve 133 for stopping the flow of the recovered water 42a flowing through the flow path is provided.

  A signal cable for transmitting a pump control signal i6 transmitted from the control unit 18 is wired to the pump 82. The pump 82 receives the pump control signal i6 and starts circulating the recovered water 42a in the recovered water circulation passage. Configured to stop.

  The recovered water closing valve 133 is configured to operate by an actuator such as a solenoid or a motor, and a signal cable for transmitting the valve opening / closing signal i7 transmitted from the control unit 18 is wired to receive the valve opening / closing signal i7. The recovery water circulation channel is opened and closed, and the flow of the recovery water 42a flowing through the recovery water circulation channel is started and stopped.

  The branch pipe 135 is configured to branch the flow of the recovered water 42a. The tip of the branch pipe 135 is connected to the recovered water inlet 78 of the oxidant gas humidifier 70 through the throttle valve 134 and the recovered water branch flow path 41 via the combustion gas heat exchanger 83 described above. The throttle valve 134 is configured to adjust the flow of the recovered water 42a. Thus, the recovered water suction port 74, the pump 82, the water treatment device 93, the branch pipe 135, the throttle valve 134, the combustion gas heat exchanger 83, the recovered water inlet 78, the water disperser 79, the filling from the liquid storage part 71 A recovered water branch circulation path for the recovered water 42a that circulates to the liquid storage section 71 via the section 80 is configured.

  The recovered water branch circulation channel is typically configured to join the recovered water circulation channel between the combustion gas heat exchanger 83 and the recovered water inlet 78, and the combustion gas heat exchanger 83 The recovered water 42 a that has been heated joins the recovered water 42 a that has passed through the circulating water heater 130 on the substantially upstream side of the recovered water inlet 78.

  Further, the recovered water 42 a decarboxylated and cooled in the gas-liquid contact tower 170 is configured to be sent to the water treatment device 86 by a pump 85 different from the pump 82 connected to the recovered water suction port 74. Yes. The recovered water 42a is purified to pure water by the water treatment device 86, and then sent to the reforming unit 9 of the fuel treatment device 7 for use in the reforming reaction.

The water treatment devices 86 and 93 have ion exchange resin packed columns 87 and 94, respectively. As the ion exchange resin used for the ion exchange resin packed columns 87 and 94 of the water treatment devices 86 and 93, an anion exchange resin is desirable. In the present embodiment, an acidic gas pollutant contained in the oxidant gas 61a, for example, sulfur oxide SO ₂ reacts as shown in the following equation.
SO ₂ + OH ⁻ → HSO ₃ ⁻ (1)
The sulfur oxide SO ₂ is ionized by reacting with the hydroxide ions OH ⁻ in the recovered water 42 a in contact with the filling section 80 according to the reaction formula (1), and is absorbed in the recovered water 42 a. And the absorbed HSO ₃ ⁻ in the recovered water 42a reacts as shown in the following equation.
HSO ₃ ⁻ + R—OH ⁻ → R-HSO ₃ ⁻ + OH ⁻ (2)
HSO ₃ ⁻ is ion-exchanged with ion-exchange resin-filled columns 87 and 94 by ion exchange with anion-exchange resin hydroxide ions OH ⁻ in ion-exchange resin-filled columns 87 and 94 according to reaction formula (1). Adsorbed on resin. At this time, hydroxide ions OH ⁻ are supplied to the recovered water 42a.

  In addition, by installing filters 88 and 95 on the downstream side of the ion exchange resin packed columns 87 and 94, respectively, the ion exchange resin is prevented from being mixed into the recovered water 42a. Furthermore, when the oxidizing gas 61a contains a large amount of solid contaminants such as dust, a solid filter can be added upstream of the ion exchange resin-filled column 94.

In the present embodiment, by providing the water treatment devices 86 and 93 using anion exchange resin in the flow path through which the recovered water 42a circulates, the recovery in gas-liquid contact with the oxidant gas 61a in the gas-liquid contact tower 170 is performed. The hydroxide ion OH ⁻ is always supplied to the water 42a. That is, the recovered water 42a that circulates is always kept alkaline, and pollutants of acidic gas such as NOx and SOx contained in the oxidant gas 61a are effectively removed. However, the water treatment devices 86 and 93 may not be provided.

  The control unit 18 heats the reforming unit 9 and circulates the circulating water 24a through the circulating water circulation channel when the reforming unit 9 reaches the circulating water / recovered water circulation start temperature T1 as the first temperature, The recovered water 42a is circulated through the recovered water circulation channel to heat the circulating water 24a, and the temperature of the circulating water 24a between the circulating water heater 130 and the fuel cell 30 is recovered based on the circulating water temperature as the second temperature. When the water circulation stop temperature T2 or the temperature of the shift section 10 of the carbon monoxide reduction section 14 reaches the carbon monoxide reduction section reaction suitable temperature T3 as the third temperature, the recovered water closing valve 133 is closed. Each part is controlled.

  Specifically, the control unit 18 receives the reforming unit temperature signal i2, the transformation unit temperature signal i3, the circulating water temperature signal i5, and the like, and based on these signals, sends the control signal i1 to the three-way valve 13. The pump control signal i 4 is transmitted to the pump 125, the pump control signal i 6 is transmitted to the pump 82, the valve opening / closing signal i 7 is transmitted to the recovered water closing valve 133, and the pump control signal i 8 is transmitted to the pump 108. ing.

  In the present embodiment, the control unit 18 controls each part of the fuel cell power generation system 1 in addition to the control of the three-way valve 13, the pump 125, the recovered water closing valve 133, and the pump 108. Thus, the fuel cell power generation system 1 can be configured more rationally.

  Below, the starting method of the fuel cell power generation system 1 controlled by the control part 18 is demonstrated. Since all the operation methods described below are controlled by the control unit 18, it is possible to control the start-up method quickly, reliably, and with the elimination of human error.

  FIG. 2 is a flowchart showing the start-up control of the fuel cell power generation system 1 by the control unit 18. A method for starting the fuel cell power generation system 1 will be described with reference to FIG. Note that FIG. 1 is referred to as appropriate for the reference numerals of the components.

  First, as a raw material fuel ignition process, supply of raw material fuel 4a from the raw material fuel supply unit (not shown) to the combustion unit 8 and supply of combustion air 5a from the combustion air supply unit (not shown) to the combustion unit 8 are started. In the combustion section 8, the raw material fuel 4a ejected from the burner nozzle is ignited and starts combustion (S101).

  Subsequently, as the reforming section preheating step, the reforming section 9 is heated by the combustion heat in the combustion section 8, and the reforming section 9 is heated and preheated (S102). The control unit 18 receives the reforming unit temperature signal i2 detected and transmitted by the reforming unit temperature detector 15, and determines whether the temperature of the reforming unit 9 has reached the circulating water / recovered water circulation start temperature T1 or more. Is determined (S103). If the temperature of the reforming unit 9 has not reached the circulating water / recovered water circulation start temperature T1 or higher, the process returns to S102 to continue the reforming unit preheating step, and the temperature of the reforming unit 9 is equal to or higher than the circulating water / recovered water circulation start temperature T1. If it is determined that the value has reached, the process proceeds to the next stage.

  Here, the circulating water / recovered water circulation start temperature T1 is set higher than the temperature at which the raw material fuel 4a undergoes the reforming reaction, and is preferably 500 ° C. to 800 ° C., more preferably 600 ° C. to 750 ° C. When the temperature for the quality reaction is 650 ° C., the temperature is set to 700 ° C.

  When the temperature of the reforming unit 9 reaches the circulating water / recovered water circulation start temperature T1 or more, the main routine (S104 to S109) starts supplying the fuel gas 3a with sufficiently reduced carbon monoxide to the fuel cell 30 and starting the power generation process. ) And a subroutine (S201 to S208) for preheating the fuel cell 30 with the circulating water 24a are executed in parallel.

  In the main routine (S104 to S109), when it is determined in S103 that the temperature of the reforming unit 9 has reached the circulating water / recovered water circulation start temperature T1 or more, as a reforming start step, by the control of the control unit 18, The supply of the raw fuel 4a to the reforming unit 9 from the raw material fuel supply unit (not shown) and the supply of the recovered water 42a stored in advance from the liquid storage unit 71 are started, and the reforming reaction in the reforming unit 9 is started. Start (S104).

  The supply of the raw fuel 4a to the reforming unit 9 is typically performed by operating a three-way valve (not shown) by the control unit 18, and the supply of 42a stored in advance from the liquid storage unit 71 is performed. Is typically performed by operating the pump 85 by the controller 18.

  Here, when the raw material fuel 4a is supplied to the reforming unit 9 by the operation of a three-way valve (not shown), the combustion unit 8 is not supplied with fuel for combustion, and the combustion stops. Thereby, the heating from the combustion unit 8 of the reforming unit 9 is stopped, but since the heat is stored in the container (not shown) and the reforming catalyst (not shown) of the reforming unit, the temperature decrease is slow. Further, typically, the reforming unit 9 is heated to a temperature higher than the temperature at which the reforming reaction is performed, and the reforming reaction is continued even if the temperature is somewhat lowered.

In the reforming unit 9, a steam reforming reaction is performed by the raw fuel 4a and the recovered water 42a. For example, when the reforming raw material is methane, a steam reforming reaction according to the following formula is performed. The recovered water 42a is heated when supplied to the reforming unit 9 and becomes water vapor generated by evaporation.
CH ₄ + H ₂ O → CO + 3H ₂ (3)
The reformed gas produced in the reforming section 9 is introduced into the shift section 10 and the following shift reaction is performed.
CO + H ₂ O → CO ₂ + H ₂ (4)
Further, the shift gas generated in the shift unit 10 is introduced into the selective oxidation unit 11 and the following carbon monoxide selective oxidation reaction is performed with the selective oxidation air.
CO + (1/2) O ₂ → CO ₂ (5)

  Immediately after startup, the shift unit 10 and the selective oxidation unit 11 are low in temperature, and even if the reformed gas is supplied, the shift reaction and the selective oxidation reaction are not sufficiently performed, and the generated fuel gas 3a is supplied to the fuel cell 30. Not suitable for doing.

  Therefore, as a preheating process for the shift unit / selective oxidation unit, the temperature of the shift unit 10 and the selective oxidation unit 11 is converted into a shift reaction and a selective oxidation reaction by the high-temperature reformed gas supplied to the shift unit 10 and the selective oxidation unit 11. The temperature is raised to a suitable temperature (S105). Since both the shift reaction and the selective oxidation reaction are exothermic reactions, the shift unit 10 and the selective oxidation unit 11 are heated by their own reaction heat generation.

  Immediately after the start-up as described above, the combustion gas 3a 'which is the fuel gas 3a and is delivered from the selective oxidation unit 11 without sufficiently reducing carbon monoxide in the gas reaches the three-way valve 13. Therefore, the control unit 18 controls the three-way valve 13 to supply the combustion gas 3a 'to the combustion unit 8, and the combustion unit 8 starts combustion using the combustion gas 3a' and the combustion air 5a.

  Next, the control unit 18 receives the transformation unit temperature signal i3 detected and transmitted by the transformation unit temperature detector 16, and the temperature of the transformation unit 10 during the temperature rise is equal to or higher than the carbon monoxide reduction unit reaction suitable temperature T3. It is determined whether or not it has been reached (S106).

  If the temperature of the shift part 10 has not reached the carbon monoxide reduction part reaction suitable temperature T3 or more, the process returns to S105 and the process after the shift part / selective oxidation part preheating step is continued. If it is determined that the temperature of the shift section 10 has reached the carbon monoxide reducing section reaction preferable temperature T3 or more, the process proceeds to the next stage.

  Here, the carbon monoxide reduction portion reaction suitable temperature T3 is a temperature suitable for the shift reaction in the shift section 10, and is preferably about 180 ° C. to 500 ° C., more preferably about 200 ° C. to 350 ° C. This is because when the temperature of the shift section 10 reaches this temperature, the shift reaction is appropriately and efficiently performed.

  When it is determined that the temperature of the shift unit 10 has reached the carbon monoxide reduction unit reaction suitable temperature T3, that is, when the temperature of the shift unit 10 reaches a temperature suitable for the shift reaction, the carbon monoxide reduction unit 14 performs reforming. Carbon monoxide in the gas is sufficiently reduced, so that the generated fuel gas 3a is suitable for supplying to the fuel cell 30.

  Therefore, as the fuel gas flow path switching step, the control unit 18 transmits a control signal i1 for operating the three-way valve 13 to supply the gas from the selective oxidation unit 11 to the fuel cell 30 to the three-way valve 13, and the fuel gas The flow path of 3a is switched (S107). By switching the three-way valve 13, the supply of the combustion gas 3 a ′ to the combustion unit 8 is stopped, and the combustion in the combustion unit 8 is stopped. However, the anode off gas 21 a generated immediately in the fuel cell 30 is sent to the combustion unit 8. Since hydrogen that has not been used for the reaction in the fuel cell remains in the anode offgas 21a, the combustion section 8 starts combustion with the anode offgas 21a and the combustion air 5a, and shifts to normal operation.

  When the fuel gas 3a in which carbon monoxide is sufficiently reduced is supplied to the fuel cell 30 and power generation is started, the fuel cell 30 rises to an operation start temperature, and after a step of increasing the power generation current, steady power generation starts. (S108). This corresponds to the power generation process. After power generation is started in the fuel cell 30, the fuel cell 3 uses the fuel gas 3 a for power generation, the anode off gas 21 a is supplied to the combustion unit 8, and combustion in the combustion unit 8 is continued.

  Next, as the exhaust heat / hot water circulation step, the control unit 18 transmits a pump control signal i4 to start the pump 125, activates the pump 125, and circulates the exhaust heat / hot water 43a to the circulation water cooler 110. (S109), and the main routine ends. The fuel cell 30 generates heat by power generation, but at least during rated operation, the circulation of the exhaust hot water 43a is started, the circulating water 24a and the exhaust hot water 43a exchange heat, and the circulating water 24a is cooled and cooled. The circulating water 24 a cools the fuel cell 30. The circulating water 24a rises in temperature when the fuel cell 30 is cooled, but the circulating water cooler 110 cools the circulating water 24a by the exhaust heat water 43a, so that the temperature is kept constant, and therefore the temperature of the fuel cell 30 is also optimal. Maintained at temperature. The exhaust heat hot water 43a is heated at this time.

  Next, a subroutine (S201 to S208) for preheating the fuel cell 30 with the circulating water 24a executed in parallel after S103 will be described.

  In the above-described shift section / selective oxidation section preheating step (S105), the temperatures of the shift section 10 and the selective oxidation section 11 are increased by the high-temperature reformed gas supplied to the shift section 10 and the selective oxidation section 11. That is, in order to quickly raise the shift unit 10 and the selective oxidation unit 11 to temperatures suitable for the shift reaction and the selective oxidation reaction, respectively, the flow rate of the raw material fuel 4a supplied to the reforming unit 9 is increased, and the shift unit 10 It is effective to increase the flow rate of the reformed gas introduced into the selective oxidation unit 11. Thereby, the start-up time of the fuel processing apparatus 7, and hence the start-up time of the fuel cell power generation system 1, can be shortened.

  However, if the flow rate of the reformed gas introduced into the shift unit 10 and the selective oxidation unit 11 is increased, the flow rate of the combustion gas 3a ′ supplied to the combustion unit 8 also increases, and the combustion amount in the combustion unit 8 also increases. Increase. As a result, the temperature of the reforming unit 9 rises excessively, leading to deterioration of the reforming catalyst and the like.

  Therefore, in the subroutine (S201 to S208), first, when it is determined in S103 that the temperature of the reforming unit 9 has reached the circulating water / recovered water circulation start temperature T1, the control unit 18 sends a valve open / close signal i7 to the recovered water shut-off valve 133 to open it, sends a pump control signal i8 to start the pump 108, and sends a pump control signal i6 to start the pump 82, Then, the pump 108 is activated to circulate the recovered water 42a and the circulating water 24a through the recovered water circulating channel and the circulating water circulating channel, respectively (S201).

  In the first heat exchange step, heat is exchanged between the recovered water 42a as the first heat medium flowing in the jacket 12 formed around the reforming unit 9 and the reformed gas in the reforming unit 9. (S202). Since the recovered water 42a introduced into the jacket 12 is stored and cooled in the liquid storage part 71 of the gas-liquid contact tower 170, the temperature of the reforming part 9 becomes excessive by exchanging heat with the reformed gas. Is prevented from rising. In addition, the temperature of the recovered water 42a that has undergone heat exchange with the jacket 12 rises. The recovered water 42a whose temperature has risen is introduced into the circulating water heater 130.

  Next, as the second heat exchange step, the circulating water heater 130 performs heat exchange between the recovered water 42a introduced into the circulating water heater 130 and the circulating water 24a as the second medium (S203). Since the temperature of the recovered water 42a introduced into the circulating water heater 130 is increasing, the temperature of the circulating water 24a is increased and the temperature of the recovered water 42a is decreased by performing heat exchange with the circulating water 24a. .

  Subsequently, as the fuel cell preheating step (S204), the circulating water 24a whose temperature has increased is introduced into the fuel cell 30 and the like, and the fuel cell 30 is heated to the operation start temperature for efficient power generation. When the temperature of the fuel cell rises, the electric resistance, loss due to an irreversible process, so-called electrode reaction resistance is reduced, and thus power generation performance is improved. On the other hand, the maximum value that can be converted from chemical energy to electrical energy by isothermal change, the so-called theoretical efficiency, decreases as the temperature of the fuel cell increases. Therefore, in order to perform efficient power generation with a fuel cell, the temperature is quickly raised to the most balanced operation start temperature in consideration of the electrical resistance, electrode reaction resistance, and theoretical efficiency, and the temperature near the operation start temperature. This is effective for efficient operation of the fuel cell power generation system. Further, here, in the case of a polymer electrolyte fuel cell, the operation start temperature is preferably about 40 ° C. to 90 ° C., more preferably about 50 ° C. to 80 ° C., considering the heat resistant temperature of the proton exchange membrane used.

  Further, as the oxidant gas humidifier preheating step, the recovered water 42a heat-exchanged with the circulating water 24a by the circulating water heater 130 is supplied from the liquid storage unit 71 to the branch pipe 134, the throttle valve 134, the recovered water branch flow path. 41, the recovered water 42a that has been heated through the combustion gas heat exchanger 83 and the recovered water inlet 78 are joined approximately upstream, and the oxidant gas humidifier 70 is preheated (S205). As a result, the oxidant gas 61a can be heated and humidified immediately after the start of the power generation process, and water vapor is supplied in a state where the oxidant gas 61a is heated, so that the oxidant gas in the fuel cell 30 is saturated with water vapor. Stay close.

  Next, the control unit 18 receives the transformation unit temperature signal i3 detected and transmitted by the transformation unit temperature detector 16 and the circulating water temperature signal i5 detected and transmitted by the circulating water temperature detector 17, and the transformation unit 10 Is the carbon monoxide reducing portion reaction preferable temperature T3 or higher, or the temperature of the circulating water 24a during the temperature rise between the circulating water heater 130 and the fuel cell 30 is higher than the recovered water circulation stop temperature T2 based on the circulating water temperature. Is determined (S206).

  The temperature of the shift unit 10 is equal to or higher than the carbon monoxide reducing unit reaction preferable temperature T3, or the temperature of the circulating water 24a between the circulating water heater 130 and the fuel cell 30 is higher than the recovered water circulation stop temperature T2 based on the circulating water temperature. If not, it returns to S202 and continues the process after a 1st heat exchange process. If it is determined that either one has reached a predetermined temperature, the process proceeds to the next stage.

  Here, carbon monoxide reduction part reaction suitable temperature T3 is the temperature mentioned above. The recovered water circulation stop temperature T2 based on the circulating water temperature is set to substantially the same temperature as the operation start temperature of the fuel cell 30, and is preferably about 40 ° C to 90 ° C, more preferably about 50 ° C to 80 ° C. This is because if the temperature of the circulating water 24a becomes higher than this, the fuel cell 30 may be overheated or the fuel cell 30 may be prevented from generating power efficiently.

  The temperature of the shift unit 10 is equal to or higher than the carbon monoxide reducing unit reaction preferable temperature T3, or the temperature of the circulating water 24a between the circulating water heater 130 and the fuel cell 30 is higher than the recovered water circulation stop temperature T2 based on the circulating water temperature. When it is determined that the temperature has reached, as the first heat exchange stop process, the control unit 18 transmits a valve opening / closing signal i7 for closing the recovered water circulation passage to the recovered water closing valve 133 to return the recovered water closing valve 133. Is closed, the circulation of the recovered water 42a in the recovered water circulation passage is stopped, and the heat exchange between the reformed gas and the recovered water 42a in the jacket 12 is stopped (S207).

Further, as the second heat exchange stop step, the circulation of the recovered water 42a is stopped, whereby the heat exchange between the recovered water 42a and the circulating water 24a in the circulating water heater 130 is also stopped (S208). The subroutine (S201 to S208) for preheating the fuel cell 30 ends.

  In S206, the temperature of the circulating water 24a between the circulating water heater 130 and the fuel cell 30 is changed to the circulating water temperature before the temperature of the shift unit 10 reaches the carbon monoxide reducing unit reaction preferable temperature T3 or higher. When the recovery water circulation stop temperature T2 or higher is reached, the first heat exchange stop step (S207) and the second heat exchange stop step (S208) are executed in the subroutine, and in the main routine, the temperature of the shift section 10 is reached. After the temperature reaches the carbon monoxide reducing portion reaction preferable temperature T3 or higher, the fuel gas flow path switching step (S107), the power generation step (S108), and the exhaust heat / hot water circulation step (S109) are performed. Further, if the temperature of the shift unit 10 reaches the carbon monoxide reduction unit reaction preferable temperature T3 or higher before the temperature of the circulating water 24a reaches the recovered water circulation stop temperature T2 or higher based on the circulating water temperature, a subroutine is executed. In the main routine, the first heat exchange stop step (S207) and the second heat exchange stop step (S208) are performed. In the main routine, the fuel gas flow path switching step (S107), the power generation step (S108), and the exhaust heat hot water circulation step (S109). Are executed almost simultaneously.

  That is, in either case, the metamorphic section 10 is preheated to a temperature suitable for the reaction, and can supply the fuel gas 3a with sufficiently reduced carbon monoxide to the fuel cell 30. The fuel cell 30 is preheated until the temperature of the water 24a reaches the recovered water circulation stop temperature T2 based on the circulating water temperature or until the shift unit 10 reaches a temperature suitable for the reaction. After that, the circulation of the exhaust hot water 43a is started.

  After the fuel cell 30 is preheated and the shift unit 10 is preheated to a temperature suitable for the reaction, the exhaust heat hot water circulation step (S109) is performed. Therefore, immediately after the fuel cell power generation system 1 is started, the fuel cell 30 Since the water is preheated by the circulating water 24a, it quickly rises to the operation start temperature, the fuel cell 30 is preheated, and after the transformation unit 10 is preheated to a temperature suitable for the reaction, the circulation of the exhaust heat hot water 42a starts. Therefore, the temperature of the circulating water 24a is prevented from rising above a predetermined temperature, and the fuel cell 30 can maintain the operation start temperature.

  Also, the reforming section preheating step (S104), the transformation section / selective oxidation section preheating process (S105), the recovery water / circulation water circulation start (S201), and the first heat exchange step (S202) are typically performed in S103. When the temperature of the reforming unit 9 is determined to have reached the circulating water / recovered water circulation start temperature T1 or more, the reforming unit 9 is executed substantially simultaneously.

  According to the fuel cell power generation system 1 and the start method of the fuel cell power generation system 1 according to the embodiment of the present invention described above, the fuel processing device 7 is cooled at the time of start-up and the reforming unit 9 is overheated. Since the reformed gas flow rate can be increased without reducing the preheating time of the carbon monoxide reduction unit 14, this heat is combined with the reaction heat in the fuel cell 30 and used for preheating the fuel cell 30. As a result, the fuel cell 30 can be quickly preheated to the operation start temperature before the start of power generation, and thus the startup time of the fuel cell power generation system 1 can be shortened. Thereby, the economical efficiency and convenience of the fuel cell power generation system 1 are also improved.

  In addition, according to the fuel cell power generation system 1 and the start method of the fuel cell power generation system 1 according to the embodiment of the present invention described above, the time during which the power generation efficiency is poor at the time of start-up can be shortened. The fuel cell power generation system 1 and the method for starting the fuel cell power generation system 1 can be provided.

  Furthermore, according to the fuel cell power generation system 1 and the start-up method of the fuel cell power generation system 1 according to the embodiment of the present invention described above, the oxidant gas 61a is not delayed from the temperature rise of the fuel cell 30. Therefore, for example, the solid polymer membrane of the fuel cell 30 is not damaged, and the life of the entire fuel cell power generation system 1 is improved.

  Note that the fuel cell power generation system 1 and the start-up method of the fuel cell power generation system 1 according to the embodiment of the present invention described above are not limited to the above-described embodiments, and are within the scope described in the claims. Various changes are possible.

In the above description, the reforming method of the fuel processing apparatus 7 has been described as a steam reforming method in which the recovered water 42a is used for reforming. However, a partial reforming method or an autothermal reforming method (autothermal method) is used. be able to. The partial reforming method is a method in which the raw material fuel 4a and air are mixed and the raw material fuel 4a is partially burned to obtain a reformed gas rich in hydrogen. In the partial reforming method, for example, a partial oxidation reaction represented by the formula (6) occurs.
CH ₄ + (1/2) O ₂ → CO + 2H ₂ (6)
Since the raw fuel 4a is directly combusted, the time until hydrogen generation can be shortened. In addition, when the molar ratio of the raw material fuel to the air is above a certain level, the reaction represented by the formula (7) may occur.
CH ₄ + O ₂ → CO + H ₂ + H ₂ O (7)

  The autothermal reforming method is a method in which air is mixed with a mixed gas of raw material fuel 4a and water vapor. That is, this is a method using both the recovered water 42a and air, and is a method in which the raw material fuel 4a is partially burned in the presence of a catalyst to obtain heat, and hydrogen is obtained by a steam reforming reaction. According to this self-thermal reforming method, the heat required for the steam reforming reaction is covered by the combustion heat of the partial oxidation reaction of the raw material fuel, which contributes to further miniaturization of the fuel processing device 7 and the fuel cell power generation system 1. It will be.

  That is, in the embodiment described above, the combustion unit is described as heating the reforming unit by burning fuel with a burner, but the combustion unit in the self-thermal reforming method is a part of the raw fuel. The reforming section that performs the steam reforming reaction is heated by the combustion heat generated by the oxidation reaction. The combustion part that heats the reforming part that performs the steam reforming reaction is a part that performs the partial oxidation reaction of the raw material fuel. Note that the heating unit is not limited to the combustion unit that burns and heats fuel or the like as described above, but includes a wide range of components that heat the reforming unit.

  In the above description, the temperature detector that detects the temperature of the carbon monoxide reduction unit 14 has been described as detecting the temperature of the transformation unit 10, but may be configured to detect the temperature of the selective oxidation unit 11. Good. In this case, the carbon monoxide reduction portion reaction suitable temperature T3 is preferably set as a temperature suitable for the selective oxidation reaction in the selective oxidation portion 11, preferably 100 ° C. to 200 ° C., more preferably 100 ° C. To about 160 ° C.

  In the above description, the circulating water 24a is heated by the circulating water heater 130 at the time of startup, preheats the fuel cell 30 to a predetermined temperature, and during the rated operation in which the fuel cell 30 generates a certain amount of power, the circulating water 24a It has been described that the fuel cell 30 is cooled by the cooler 110. In this case, the fuel cell power generation system can have a simpler configuration. However, a circulation path for circulating water as preheating water and a circulation path for circulating water as cooling water for cooling the fuel cell 30 may be provided separately. In this case, it is possible to flexibly respond appropriately according to the design conditions and use of the fuel cell power generation system.

  In the above description, the circulating water heater 130 and the circulating water cooler 110 have been described as being configured separately, but may be configured integrally to form a three-fluid heat exchanger. In this case, the three-fluid heat exchanger is a three-fluid heat exchanger that exchanges heat between the recovered water 42a and the circulating water 24a at the time of startup, and further exchanges heat between the circulating water 24a and the exhaust hot water 43a during rated operation. A plate type or multi-tube type heat exchanger is preferably used.

  In the above description, the exhaust heat hot water 43a is used as the refrigerant of the circulating water cooler 110. However, a fluid other than the exhaust heat hot water may be used, or an air cooling type using the circulating water cooler 110 as an air fin cooler. Alternatively, the circulating water 24a may be cooled by a cooling tower.

  In the above description, the carbon monoxide reduction unit 14 has been described as including the shift conversion unit 10 and the selective oxidation unit 11, but a configuration that can sufficiently reduce the carbon monoxide in the reformed gas. For example, the selective oxidation unit 11 may not be provided. In this case, the apparatus can have a more compact configuration.

1 is a schematic block diagram of a fuel cell power generation system according to an embodiment of the present invention. It is the flowchart shown about starting control of the fuel cell power generation system by the control part of the fuel cell power generation system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell power generation system 7 Fuel processing apparatus 8 Combustion part 9 Reforming part 10 Transformation part 11 Selective oxidation part 12 Jacket 13 Three-way valve 14 Carbon monoxide reduction part 15 Reforming part temperature detector 16 Transformation part temperature detector 17 Circulating water Temperature detector 18 Control unit 30 Fuel cell 41 Collected water branch flow path 70 Oxidant gas humidifier 71 Liquid storage unit 83 Combustion gas heat exchanger 110 Circulating water cooler 114 Gas gas heat exchanger 120 Hot water storage tank 130 Circulating water heater 133 Recovery water closing valve 134 Throttle valve 135 Branch pipe 170 Gas-liquid contact device 3a Fuel gas 3a 'Combustion gas 4a Raw material fuel 5a Combustion air 6a Combustion gas 21a Anode off gas 22a Cathode off gas 24a Circulating water 42a, 42A, 42B, 42C Water 43a Waste hot water 61a Oxidant gas 63a Mixed gas 64a Exhaust gas T1 Circulating water / recovered water circulation Start temperature T2 Recovered water circulation stop temperature T3 based on circulating water temperature Carbon monoxide reduction unit reaction suitable temperature i1 control signal i2 reforming unit temperature signal i3 transformation unit temperature signal i4 pump control signal i5 circulating water temperature signal i6 pump control signal i7 valve Open / close signal i8 Pump control signal

Claims (4)

A fuel cell that generates water by generating an electrochemical reaction between a fuel gas and an oxidant gas and generates water;
A storage device for recovering and storing the generated water as recovered water;
Reforming the raw material fuel and supplying the recovered water or air to reform the raw material fuel to generate a reformed gas; and a heat exchanging unit formed around the reforming unit for heat exchange; A fuel processing apparatus comprising: a heating unit that heats the reforming unit; and a carbon monoxide reduction unit that reduces the carbon monoxide in the reformed gas to generate the fuel gas;
A preheating water heater for exchanging heat between the recovered water and preheating water for preheating the fuel cell;
From the storage device, the heat exchange unit, the preheating water heater, and the recovered water circulation passage for the recovered water reaching the storage device;
The preheating water heater from the fuel cell, and a preheating water circulation passage for preheating water to the fuel cell;
Fuel cell power generation system. An oxidant gas humidifier configured integrally with the storage device and humidifying the oxidant gas by circulating the recovered water;
A branching unit that is disposed in the recovered water circulation channel between the storage device and the heat exchange unit, and branches the recovered water circulation channel;
A flow path from the branching means to the oxidant gas humidifier;
A recovery water circulation passage closing means disposed in the recovery water circulation passage between the branching means and the heat exchanging section and closing the recovery water circulation passage;
The fuel cell power generation system according to claim 1. When the reforming section is heated and the reforming section reaches the first temperature, the preheating water is circulated through the preheating water circulation passage, and the recovered water is circulated through the recovery water circulation passage. When the preheating water is heated, and the temperature of the preheating water between the preheating water heater and the fuel cell becomes the second temperature, or the temperature of the carbon monoxide reduction unit becomes the third temperature. A control device for closing the recovered water circulation passage closing means;
The fuel cell power generation system according to claim 2. A reforming section preheating step of supplying the feedstock fuel and water or air to reform the feedstock fuel and heating the reforming section that generates reformed gas;
A first heat exchanging step of exchanging heat between the reformed gas and the first medium when the reforming unit reaches a first temperature;
A second heat exchange step for exchanging heat between the first medium and the second medium;
A fuel cell preheating step in which the second medium heats a fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas;
The second medium is the second temperature, or the temperature of the carbon monoxide reduction unit that reduces the carbon monoxide in the reformed gas and generates the carbon monoxide reduced gas as the fuel gas is the third temperature. A first heat exchange stopping step for stopping heat exchange between the reformed gas and the first medium when
A method for starting a fuel cell power generation system.

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