JP2005071834A - Exhaust heat recovery system of fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery system for a fuel cell system in which the deterioration of a cooling effect of the fuel cell caused by fluid for cooling a fuel cell can be prevented without making a radiator large in size or electric power consumption high. <P>SOLUTION: This exhaust heat recovery system of the fuel cell system is constituted such that a heat exchanger 14 for cooling the cell where exhaust heat is recovered from the fluid for cooling the cell, a heat exchanger 15 for a heat receiving gas side to recover the exhausted heat from the heat receiving side gas that is discharged outside the fuel cell system or that flows through the interior of the fuel cell system, a heat storage device 18 to store the recovered exhausted heat, and a radiator 19 to radiate the heat in order to maintain a temperature of the fluid for cooling the fuel cell below a temperature for cooling are installed. In the case an inflow temperature of the fluid for cooling the fuel cell into the fuel cell 10 is not lower than a temperature for determining a bypass state switching, or in the case the amount of stored heat of the heat storage device 18 is not lower than a heat amount for determining the bypass state switching, bypass means 25, 35 to bypass exhaust heat recovery in the heat exchanger 15 for the heat receiving side gas are installed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery cooling heat exchanger that recovers exhaust heat by heat exchange with a battery cooling fluid of a fuel cell that generates power using fuel gas supplied from a reformer, a reformer, and a fuel cell. A heat exchanger for heat transfer side gas that recovers exhaust heat by heat exchange with the heat transfer side gas that is discharged outside the fuel cell system or flows through the fuel cell system, and a heat exchanger for battery cooling And a heat storage device for storing exhaust heat recovered from the heat exchanger for the heat transfer side gas, and a heat radiator that operates to dissipate heat in order to maintain the temperature of the battery cooling fluid below a temperature suitable for cooling. The present invention relates to a system for exhaust heat recovery.

  Most of the exhaust heat recovery systems of such fuel cell systems recover heat stored in the hot water storage tank by using exhaust heat recovery fluid such as water from the fuel cell system. Met. For the purpose of further improving the efficiency of exhaust heat recovery from the fuel cell system, the heat of the exhaust gas from the reformer, the heat of the exhaust gas from the carbon monoxide converter, and the carbon monoxide selective oxidizer There has also been proposed an exhaust heat recovery system that recovers a large amount of exhaust heat from the entire fuel cell system by performing exhaust heat recovery from the heat of each exhaust gas (see, for example, Patent Document 1).

  In addition, since the cathode exhaust gas discharged from the cathode part of the fuel cell and the anode exhaust gas discharged from the anode part absorb the heat of reaction during power generation, the cathode exhaust gas and anode exhaust gas, the exhaust heat recovery fluid, By exchanging heat between the two, exhaust heat recovery from these gases can also be performed, thereby increasing the exhaust heat recovery efficiency of the fuel cell system.

JP 2001-176527 A

  In the exhaust heat recovery system of the fuel cell system as described above, when the amount of heat stored in the hot water tank increases and the temperature of the exhaust heat recovery fluid exchanging heat with the battery cooling fluid rises, the fuel cell The temperature difference between the temperature of the battery cooling fluid discharged from the battery and the temperature of the exhaust heat recovery fluid becomes small, and there arises a problem that the battery cooling effect cannot be sufficiently obtained. For this reason, for example, a heat radiator such as a heat radiating fan is provided in the exhaust heat recovery system, and when the amount of heat stored in the hot water storage tank increases to a predetermined amount or more, the heat radiator is operated and the battery cooling fluid of the fuel cell is operated. Measures have been taken to reduce the temperature of the exhaust heat recovery fluid or the temperature of the exhaust heat recovery fluid to sufficiently obtain the cooling effect of the fuel cell by the battery cooling fluid. At that time, the radiator is required to have an ability to dissipate all the newly recovered heat so as not to store more heat than is currently stored in the hot water tank.

  However, since the exhaust heat recovery system described in Patent Document 1 is intended to recover a large amount of heat from the fuel cell system, the amount of heat stored in the hot water storage tank provided in the exhaust heat recovery system exceeds a predetermined amount of heat. In order to dissipate the large amount of heat that is newly recovered, it is necessary to install a large radiator, and as a result, a large amount of power is required to drive the large radiator and a large installation is required. The problem of requiring space occurs.

  The present invention has been made in view of the above-described problems, and its object is to cool a battery without increasing the size and power consumption of a radiator while recovering a large amount of exhaust heat from a fuel cell system. Another object of the present invention is to provide a waste heat recovery system for a fuel cell system that can prevent a decrease in the cooling effect of the fuel cell due to the working fluid.

  In order to achieve the above object, the first characteristic configuration of the exhaust heat recovery system of the fuel cell system according to the present invention is a battery cooling fluid of a fuel cell that generates power using fuel gas supplied from a reformer. Heat transfer side gas exhausted outside the fuel cell system in which the heat exchanger for recovering exhaust heat by heat exchange, the reformer and the fuel cell are provided, or flowing through the fuel cell system A heat exchanger for heat transfer side gas that recovers exhaust heat by heat exchange with, a heat storage device that stores the exhaust heat recovered from the heat exchanger for battery cooling and the heat exchanger for heat transfer side gas, and An exhaust heat recovery system of a fuel cell system provided with a radiator that performs heat radiation operation in order to maintain a temperature of the battery cooling fluid below a temperature suitable for cooling, wherein the battery cooling fluid is supplied to the fuel cell. Inflow temperature is bypassed Bypass means for bypassing exhaust heat recovery in the heat exchanger for the heat transfer side gas is provided when the temperature for switching determination becomes higher than or when the heat storage amount of the heat storage device becomes equal to or higher than the heat amount for bypass state switching determination. There is in point.

  According to the first characteristic configuration described above, when the inflow temperature of the battery cooling fluid to the fuel cell is equal to or higher than the determination temperature for bypass state switching, or when the heat storage amount of the heat storage device is equal to or higher than the temperature for determination of bypass state switching. Since the bypass means operates so that the exhaust heat recovery in the heat exchanger for heat transfer side gas is bypassed, it is possible to suppress further temperature rise of the battery cooling fluid or further heat storage to the heat storage device. it can. As a result, while reducing the size and power consumption of the radiator, it is possible to prevent the fuel cell cooling effect from being lowered by the battery cooling fluid and to exhibit the original performance of the fuel cell.

  According to a second characteristic configuration of the exhaust heat recovery system of the fuel cell system according to the present invention, in addition to the first characteristic configuration, the heat transfer side gas is burner combustion exhaust gas of the reformer, cathode exhaust gas of the fuel cell. And at least one of the anode exhaust gas of the fuel cell.

  According to the second characteristic configuration described above, the burner combustion exhaust gas of the reformer, the cathode exhaust gas of the fuel cell, and the anode exhaust gas of the fuel cell, which do not affect the power generation performance of the fuel cell system, even when used, are used for exhaust heat recovery. Since it is used as a heat source, the exhaust heat recovery efficiency of the exhaust heat recovery system can be improved without reducing the power generation efficiency of the fuel cell system.

  According to a third feature of the exhaust heat recovery system for a fuel cell system according to the present invention, in addition to the first or second feature, the bypass means bypasses the heat exchanger for the heat transfer side gas. The heat transfer side gas is configured to flow by bypass through.

  According to the third characteristic configuration, when bypassing the heat exchanger side gas heat exchanger, the bypass means is configured to bypass the heat transfer side gas generated and discharged in the fuel cell system. Therefore, it is possible to eliminate the pressure loss that occurs when the heat transfer side gas flows into the heat exchanger for the heat transfer side gas, and to smoothly discharge the heat transfer side gas from the fuel cell system. The power generation performance in can be improved.

  A fourth characteristic configuration of the exhaust heat recovery system of the fuel cell system according to the present invention is the heat transfer side separately for a plurality of types of gases as the heat transfer side gas in addition to the first or second characteristic configuration. A heat exchanger for gas is provided, and the heat storage device is configured in such a manner that a plurality of the heat transfer side gas heat exchangers are passed in series through the exhaust heat recovery fluid, and the bypass means includes the plurality of heat exchangers. The exhaust heat recovery fluid is bypassed through one bypass passage that bypasses all of the heat exchanger side gas heat exchanger.

  According to the fourth characteristic configuration, each heat transfer side gas heat exchanger is individually connected when the exhaust heat recovery fluid is bypassed so that the bypass means bypasses the plurality of heat transfer side gas heat exchangers. It is not necessary to bypass, and it is only necessary to provide a bypass path for bypassing all the heat transfer side gas heat exchangers at once, so that the configuration of the bypass means and its control can be simplified.

<First Embodiment>
An exhaust heat recovery system for a fuel cell system according to the present invention, which will be described below with reference to the drawings, is an improved fuel gas containing hydrogen-containing gas obtained by reforming a hydrocarbon-based raw fuel gas as a fuel gas. This is an exhaust heat recovery system that recovers exhaust heat from a fuel cell system that includes a gas purification device R and a fuel cell 10 that generates power using the hydrogen-containing gas supplied from the reformer R.
In the exhaust heat recovery system of the fuel cell system according to the present invention, the exhaust heat is recovered by heat exchange with the battery cooling fluid of the fuel cell 10 that generates power using the fuel gas supplied from the reformer R. Exhaust heat by exchanging heat with the heat transfer side gas that is discharged to the outside of the fuel cell system in which the battery cooling heat exchanger 14, the reformer R, and the fuel cell 10 are provided or flows through the fuel cell system. Heat transfer side gas heat exchangers 15, 16, and 17 for recovering heat, and heat storage devices for storing exhaust heat recovered from the battery cooling heat exchanger 14 and the heat transfer side gas heat exchangers 15, 16, and 17 18 and a radiator 19 that operates to dissipate heat in order to maintain the temperature of the battery cooling fluid below a temperature suitable for cooling the fuel cell. In the exhaust heat recovery system of the fuel cell system according to the first embodiment, the amount of heat stored in the heat storage device 18 is bypassed when the inflow temperature of the cell cooling fluid to the fuel cell becomes equal to or higher than the bypass state switching determination temperature. Bypass means 25, 35, 26, 36, 27, and 37 are provided to bypass exhaust heat recovery in the heat exchangers 15, 16, and 17 when the heat amount for state switching determination is greater than or equal to. It is characterized by that.

  The fuel cell 10 includes an anode 12 to which fuel gas (hydrogen-containing gas) is supplied, a cathode 13 to which oxygen gas is supplied, and an electrolyte membrane 11 provided between the anode 12 and the cathode 13. The fuel cells are stacked to constitute one fuel cell. Then, after hydrogen-containing gas (fuel gas) supplied from the reformer R and oxygen gas are subjected to a power generation reaction, cathode exhaust gas (an example of heat transfer side gas) is discharged from the cathode 13, and from the anode 12. Anode exhaust gas (an example of heat transfer side gas) is discharged. A battery cooling water (an example of a battery cooling fluid) that cools itself to an appropriate temperature is passed through the fuel cell 10, and the battery cooling water that has been heated by the fuel cell 10 is a target for heat recovery. can do. Further, since the cathode exhaust gas and the anode exhaust gas receive reaction heat during power generation, these gases can be used as exhaust heat recovery targets as heat transfer side gases.

  The reformer R is a device that receives supply of raw fuel to generate a hydrogen-containing gas, and supplies the hydrogen-containing gas to a fuel cell. The desulfurizer 1 performs desulfurization of the supplied hydrocarbon-based raw fuel. A water vapor generator 2 that vaporizes water to generate water vapor, a reformer 3 that reacts the desulfurized raw fuel gas with water vapor to generate a hydrogen-containing gas, and a monoxide contained in the hydrogen-containing gas Carbon monoxide converter (CO converter) 5 that converts carbon to carbon dioxide, and the hydrogen-containing gas that has passed through the carbon monoxide converter 5 selectively oxidizes a small amount of carbon monoxide to contain hydrogen. A carbon monoxide selective oxidizer (CO selective oxidizer) 6 for further reducing the concentration of carbon monoxide contained in the gas is provided.

The desulfurizer 1 first desulfurizes the raw fuel gas when a city gas containing methane gas (CH ₄ ) as a main component and a sulfur compound added as an odorant is used as the raw fuel gas. Used as an apparatus for removing the sulfur compound. In this desulfurization treatment, a desulfurization method is used in which hydride obtained by adding hydrogen to the raw fuel gas and reacting both with a catalyst is adsorbed on zinc oxide or the like. Hydrogen added to the raw fuel gas for desulfurization may be supplied directly from a separately provided hydrogen tank, or a part of the hydrogen-containing gas generated in the reformer 3 may be introduced into the desulfurizer 1. is there.

  The reformer 3 activates the reaction between the desulfurized raw fuel gas (methane gas) and the steam supplied from the steam generator 2 by the reforming catalyst, and generates a hydrogen-containing gas containing hydrogen and carbon monoxide. It is a device to generate. During this reaction, the reforming catalyst is maintained at a temperature of, for example, 650 ° C. to 750 ° C. using the combustion unit 4 equipped with a burner, and methane gas is steam reformed to generate a hydrogen-containing gas. In this embodiment, the anode exhaust gas discharged from the anode of the fuel cell 10 is recovered and used as the fuel of the combustion unit 4, and the burner combustion exhaust gas of the combustion unit 4 is used as a heat transfer side gas for exhaust heat recovery. It is targeted.

  The carbon monoxide converter 4 is a device that converts carbon monoxide contained in the hydrogen-containing gas supplied from the reformer 3 into carbon dioxide. The conversion of carbon monoxide to carbon dioxide is to prevent electrode poisoning that may occur when carbon monoxide is supplied to the fuel cell. At this time, the carbon monoxide conversion catalyst 6 for converting carbon monoxide into carbon dioxide is heated to about 200 ° C. by a temperature rising heater (not shown), and the carbon monoxide and water vapor are converted by the carbon monoxide conversion catalyst 6. When activated, it is transformed into carbon dioxide and hydrogen.

  The carbon monoxide selective oxidizer 5 is a device that selectively oxidizes the unreacted carbon monoxide to carbon dioxide in the carbon monoxide converter 4, thereby converting the hydrogen-containing gas supplied to the fuel cell into the hydrogen-containing gas. The carbon monoxide concentration contained can be made extremely low.

  As described above, the components of the fuel cell system (the reformer R and the fuel cell 10) have been described. However, the exhaust heat recovery system according to the present invention uses the heat discharged from the fuel cell system as shown in FIG. The heat transfer side gas heat exchanger 17, the heat transfer side gas heat exchanger 16, the heat transfer side gas heat exchanger 15, and the battery cooling heat exchanger 14 are sequentially collected and stored in the hot water storage tank (of the heat storage device). Example) It is configured to store heat in 18.

  The hot water storage tank 18 stores water (an example of exhaust heat recovery fluid) inside the hot water storage tank 18 and causes the water to flow through the exhaust heat recovery fluid path 8 using the pump 21, and heat transfer side gas heat exchanger 17, heat transfer. The exhaust heat from the fuel cell system is recovered by heat exchange sequentially performed in the side gas heat exchanger 16, the heat transfer side gas heat exchanger 15, and the battery cooling heat exchanger 14. Is configured to supply hot water to the outside.

  The radiator 19 is radiated to maintain the temperature of the battery cooling water below the temperature suitable for cooling the fuel cell. In this embodiment, the radiator 19 is provided in the exhaust heat recovery fluid path 8 after exiting the hot water tank 18. ing. The heat dissipating capacity may be any capacity that can dissipate the same amount of heat as is recovered by battery cooling water. Therefore, the exhaust heat recovery fluid that flows into the battery cooling heat exchanger 14 while the radiator 19 is in operation is an exhaust heat recovery fluid whose temperature has been lowered by the radiator 19. Heat can be sufficiently removed from the battery cooling water flowing into the exchanger 14.

Hereinafter, battery cooling water, cathode exhaust gas, anode exhaust gas, and burner combustion exhaust gas that exchange heat with the exhaust heat recovery fluid will be described.
The battery cooling water flowing through the battery cooling fluid path 7 is provided to cool the fuel cell 10, and is circulated between the battery cooling heat exchanger 14 and the fuel cell 10 by the pump 20 for exhaust heat recovery. Heat exchange is performed with the exhaust heat recovery fluid flowing through the fluid path 8.

  The cathode exhaust gas is a gas after the power generation reaction that is discharged from the cathode portion 13 of the fuel cell 10, and flows into the heat transfer side gas heat exchanger 15 through the bypass valve 25, and passes through the exhaust heat recovery fluid path 8. Heat exchange is performed with the flowing exhaust heat recovery fluid. The anode exhaust gas is a gas after power generation reaction discharged from the anode portion 12 of the fuel cell, and flows into the heat transfer side gas heat exchanger 16 through the bypass valve 26 and passes through the exhaust heat recovery fluid path 8. Heat exchange is performed with the flowing exhaust heat recovery fluid. The burner combustion exhaust gas is a gas after the anode exhaust gas is burned by the combustion unit 4 and flows into the heat exchanger-side gas heat exchanger 17 through the bypass valve 27 and passes through the exhaust heat recovery fluid path 8. Heat exchange is performed with the flowing exhaust heat recovery fluid.

  The heat exchangers 15, 16, 17 for the heat transfer side gas are additionally provided with bypass means (bypass valve and bypass passage) for bypassing the cathode exhaust gas, the anode exhaust gas, and the burner combustion gas flowing into the heat exchanger side gas heat exchangers 15, 16, 17. . For example, the heat transfer side gas heat exchanger 15 is provided with a bypass valve 25 and a bypass passage 35, and the heat transfer side gas heat exchanger 16 is provided with a bypass valve 26 and a bypass passage 36. The side gas heat exchanger 17 is provided with a bypass valve 27 and a bypass passage 37.

  Next, the operation of the bypass means when the inflow temperature of the battery cooling water to the fuel cell 10 is equal to or higher than the bypass state switching determination temperature or when the heat storage amount of the hot water storage tank is equal to or higher than the bypass state switching determination heat amount will be described below. explain. The monitoring of the temperature and the amount of heat storage and the operation control of the bypass means based on the results are executed by a separately provided arithmetic control unit (not shown).

  First, the inflow temperature of the battery cooling water to the fuel cell 10 is monitored using a thermometer T. If the inflow temperature is equal to or higher than a predetermined value (over the bypass state switching determination temperature), it is excessive in the hot water storage tank 18. It can be determined that the correct heat storage is performed. Similarly, when the amount of water in the hot water tank and its temperature are derived from a thermometer T and a water amount sensor (not shown), and the amount of stored heat is equal to or greater than a predetermined value (greater than the amount of heat for bypass state switching determination). It can be determined that excessive heat storage is performed in the hot water storage tank 18.

  In the exhaust heat recovery system of the fuel cell system, when the temperature of the battery cooling water is equal to or higher than the bypass state switching determination temperature, or when the heat storage amount in the hot water storage tank 18 is equal to or higher than the bypass state switching determination heat amount, the cathode The arithmetic and control unit switches the bypass valves 25, 26, and 26 so that the exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas bypass the heat exchanger side gas heat exchangers 15, 16, 17, and the cathode exhaust gas, the anode exhaust gas. And the burner combustion exhaust gas is passed through the bypass passages 35, 36 and 37. As a result, exhaust heat recovery of the fuel cell system is not performed in the heat exchangers 15, 16, and 17 for the heat transfer side gas, and further temperature rise of the battery cooling water or further heat storage in the hot water storage tank 18 is suppressed. Therefore, it is possible to prevent the cooling effect of the fuel cell 10 from being lowered by the battery cooling water while providing the small-sized and low power consumption radiator 19. It is to be noted that the radiator 19 is appropriately operated so that the battery cooling water is not higher than the temperature suitable for cooling the fuel cell 10.

  Further, when bypassing the heat exchanger-side gas heat exchangers 15, 16, and 17 to the cathode exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas as the heat transfer side gas, a bypass means is generated in the fuel cell system. Since the heat transfer side gas to be discharged is configured to flow by bypass, the pressure loss that occurs when the heat transfer side gas flows into the heat transfer side gas heat exchangers 15, 16, 17 is eliminated, The heat transfer side gas can be smoothly discharged from the fuel cell system.

Second Embodiment
The exhaust heat recovery system of the fuel cell system according to the second embodiment shown in FIG. 2 is different from the exhaust heat recovery system of the fuel cell system according to the first embodiment illustrated in FIG. For exhaust heat recovery through one bypass passage 38 that bypasses all of the heat exchangers 15, 16, 17 for heat transfer side gas for recovering exhaust heat from the heat transfer side gas (cathode exhaust gas, anode exhaust gas, burner combustion exhaust gas) The fluid is configured to bypass.

  Specifically, heat exchanger-side gas heat exchangers 15, 16, and 17 that perform heat exchange between the cathode exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas as the heat transfer side gas and the exhaust heat recovery fluid are respectively connected in series. Although provided in the same manner as in the first embodiment, in this embodiment, the bypass means is configured such that the cathode exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas are switched from the bypass valve 28 to the heat transfer side gas heat exchanger 15, All of 16 and 17 are configured to bypass flow through one bypass path 38. As a result, a simple system configuration in which the bypass valve 28 and the bypass passage 38 are provided can be achieved.

  During normal exhaust heat recovery, the hot water storage tank 18 stores water (an example of exhaust heat recovery fluid) in the interior thereof, and causes the water to flow through the exhaust heat recovery fluid path 8 by the pump 21 and passes through the bypass valve 28. The heat exchange gas heat exchanger 17, the heat exchange gas heat exchanger 16, the heat exchange gas heat exchanger 15, and the battery cooling heat exchanger 14 perform heat exchange performed in order from the fuel cell system. The exhaust heat is recovered, and on the other hand, water is supplied from the outside and hot water is supplied to the outside.

  And when the inflow temperature of the battery cooling water to the fuel cell is equal to or higher than the bypass state switching determination temperature or when the heat storage amount of the hot water tank is equal to or higher than the bypass state switching determination heat amount, the same as in the first embodiment. By switching the exhaust heat recovery fluid passage to the bypass passage 38, the heat transfer side gas heat exchangers 15, 16, and 17 do not perform exhaust heat recovery of the fuel cell system, and the temperature of the battery cooling water is further increased. It is comprised so that the further heat storage to the raise or the hot water storage tank 18 may be suppressed.

<Another embodiment>
<1>
The exhaust heat recovery system of the fuel cell system shown in FIG. 3 differs from the exhaust heat recovery system of the fuel cell system according to the first embodiment illustrated in FIG. 1 in the form of exhaust heat recovery.
Specifically, the heat exchange fluid flowing through the heat exchange fluid passage 9 by the pump 22 is supplied to the battery cooling water, the cathode exhaust gas in the battery cooling heat exchanger 14 and the heat exchanger side gas heat exchangers 15, 16, and 17. The heat exchange fluid that exchanges heat with the anode exhaust gas and the burner combustion exhaust gas and that flows through the heat exchange fluid passage 9 and the exhaust heat recovery fluid that flows through the exhaust heat recovery fluid passage 8 is exchanged in the heat exchanger 23. Is configured to do.

<2>
The exhaust heat recovery system of the fuel cell system shown in FIG. 4 is different from the exhaust heat recovery system of the fuel cell system according to the first embodiment illustrated in FIG. A radiator 19 is provided in the cell cooling fluid path 7 from the exchanger 14 to the fuel cell 10. With this system configuration, the temperature control of the battery cooling water flowing into the fuel cell 10 can be reliably performed by controlling the operation of the radiator 19 based on the temperature monitored by the thermometer T.

<3>
The exhaust heat recovery system of the fuel cell system shown in FIG. 5 is different from the exhaust heat recovery system of the fuel cell system according to the first embodiment illustrated in FIG. The system has a system configuration in which exhaust heat of cathode exhaust gas, anode exhaust gas, and burner combustion exhaust gas as heat transfer side gas is recovered by battery cooling water. Specifically, the battery cooling water exiting the fuel cell 10 passes through the pump 20 to the heat transfer side gas heat exchanger 15, the heat transfer side gas heat exchanger 16, and the heat transfer side gas heat exchanger 17. The exhaust heat of the cathode exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas is recovered in order, and then the exhaust heat recovered in the exhaust heat recovery fluid is passed in the battery cooling heat exchanger 14.

  5 illustrates a system configuration in which the bypass means bypasses each of the cathode exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas. However, as illustrated in FIG. 2, the heat for the heat transfer side gas is illustrated. You may comprise so that a battery cooling water may be made to flow by bypass through one bypass path which bypasses all the exchangers 15, 16, and 17. FIG.

<4>
In the above-described embodiment, the case where the cathode exhaust gas, the anode exhaust gas, and the burner combustion exhaust gas as the heat transfer side gas are used for exhaust heat recovery has been described. However, as the heat transfer side gas, only at least one of these gases is used. May be used for exhaust heat recovery. When only one of these gases is used for exhaust heat recovery, in the system configuration of FIG. 1, the bypass valve may be switched so that the gas that is not subject to exhaust heat recovery is bypassed.

<5>
In the exhaust heat recovery system of the fuel cell system shown in FIGS. 1 to 4, the heat exchanger-side gas heat exchanger 17, the heat exchanger-side gas heat exchanger 16, the heat exchanger-side gas heat exchanger 15, and the battery The exhaust heat recovery fluid (or heat exchange fluid) is made to flow so as to recover the exhaust heat in the order of the cooling heat exchanger 14, but conversely, the battery cooling heat exchanger 14 and the heat transfer side The exhaust heat recovery fluid (or heat exchange fluid) flows through the gas heat exchanger 15, the heat transfer side gas heat exchanger 16, and the heat transfer side gas heat exchanger 17 in order to recover the exhaust heat. It is also possible to modify so that
Similarly, in the exhaust heat recovery system of the fuel cell system shown in FIG. 5, the battery cooling water exiting the fuel cell 10 passes through the pump 20 and then the heat transfer side gas heat exchanger 15, the heat transfer side gas heat exchanger. 16 and the heat transfer side gas heat exchanger 17 are passed in this order, and then flow into the battery cooling heat exchanger 14. On the contrary, the battery cooling water is supplied to the heat transfer side. The gas heat exchanger 17, the heat transfer side gas heat exchanger 16 and the heat transfer side gas heat exchanger 15 are passed through in this order, and then flow into the fuel cell 10, and then the fuel cell 10 exits. It is also possible to modify the cooling water so as to flow into the battery cooling heat exchanger 14 via the pump 20.

Functional block diagram of the exhaust heat recovery system of the fuel cell system Another functional block diagram of the exhaust heat recovery system of the fuel cell system Another functional block diagram of the exhaust heat recovery system of the fuel cell system Another functional block diagram of the exhaust heat recovery system of the fuel cell system Another functional block diagram of the exhaust heat recovery system of the fuel cell system

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell 14 Heat exchanger for battery cooling 15 Heat exchanger for heat transfer side gas 18 Hot water storage tank (heat storage device)
19 Radiator 25 Bypass valve 35 Bypass path

Claims (4)

A battery cooling heat exchanger that recovers exhaust heat by heat exchange with a battery cooling fluid of a fuel cell that generates power using fuel gas supplied from a reformer;
Heat for heat transfer side gas that recovers exhaust heat by heat exchange with heat transfer side gas that is discharged outside the fuel cell system in which the reformer and the fuel cell are provided or flows through the fuel cell system An exchange,
A heat storage device for storing exhaust heat recovered from the battery cooling heat exchanger and the heat exchanger gas heat exchanger;
An exhaust heat recovery system for a fuel cell system provided with a radiator that radiates heat to maintain the temperature of the battery cooling fluid below a temperature suitable for cooling,
The heat transfer side gas when the inflow temperature of the battery cooling fluid into the fuel cell becomes equal to or higher than the bypass state switching determination temperature or when the heat storage amount of the heat storage device exceeds the bypass state switching determination heat amount. An exhaust heat recovery system for a fuel cell system provided with bypass means for bypassing exhaust heat recovery in a heat exchanger for use.   2. The exhaust heat recovery of the fuel cell system according to claim 1, wherein the heat transfer side gas includes at least one of burner combustion exhaust gas of the reformer, cathode exhaust gas of the fuel cell, and anode exhaust gas of the fuel cell. system.   The exhaust of the fuel cell system according to claim 1 or 2, wherein the bypass means is configured to bypass the heat transfer side gas through a bypass path that bypasses the heat transfer side gas heat exchanger. Heat recovery system. The heat exchanger for the heat transfer side gas is provided separately for each of the plurality of types of gases as the heat transfer side gas,
The heat storage device is configured in such a manner that a plurality of the heat transfer side gas heat exchangers are passed in series through a waste heat recovery fluid,
The bypass means is configured to bypass the exhaust heat recovery fluid through one bypass passage that bypasses all of the plurality of heat transfer side gas heat exchangers. The exhaust heat recovery system of the fuel cell system described.

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