JP6171114B1 - Fuel cell system - Google Patents

Abstract

The present invention provides a fuel cell system capable of simplifying and compacting a system by eliminating a radiator. A fuel cell system includes a fuel cell that supplies fuel gas and reformed water to generate power, and an exhaust heat exchanger that performs heat exchange between the exhaust of the fuel cell and a refrigerant. , A refrigerant tank 30 for storing refrigerant to be supplied to the exhaust heat exchanger 31, a first delivery side pipe 36 and a first return side pipe 38 for circulating the refrigerant between the refrigerant tank 30 and the exhaust heat exchanger 31, A heat recovery pump 40 that circulates refrigerant in the one delivery side pipe 36 and the first return side pipe 38 is provided. The length of the first delivery side pipe 36 is set to be twice or more the shortest distance connecting the refrigerant tank 30 and the exhaust heat exchanger 31. [Selection] Figure 1

Description

  The present invention relates to a fuel cell system capable of supplying electric power and hot water.

  The following is known as a conventional fuel cell system used in a house or the like (see Patent Document 1).

Japanese Patent Laying-Open No. 2015-002093

  In the fuel cell system, in order to recover the heat generated during power generation, off-gas heat is recovered as hot water using a heat exchanger and stored in a tank, and the stored hot water is used for hot water supply and heating as needed. To be done.

  In the conventional fuel cell system, the water used for power generation is recovered from the burner exhaust gas containing water vapor. Therefore, it is necessary to cool the burner exhaust gas. At that time, it is necessary to cool the burner exhaust gas to a certain temperature or lower in order to recover a sufficient amount of water. The burner exhaust gas is cooled by exchanging heat with the heat recovery water (refrigerant), but if the temperature of the heat recovery water rises due to a situation such as the refrigerant tank becoming full, the burner exhaust gas can be cooled sufficiently. It becomes impossible to secure a sufficient amount of water necessary for power generation. Therefore, it is necessary to keep the temperature of the heat recovery water below a certain temperature. A radiator that can release the heat of the refrigerant to the outside and a radiator fan that blows air to the radiator are arranged on the piping path. Cooling is done.

  However, in the conventional fuel cell system, in addition to the space for the radiator, a ventilation path and a radiator fan are required, so that the system is increased in size and cost.

  An object of the present invention is to provide a fuel cell system that can simplify and compact a system by eliminating a radiator in consideration of the above facts.

  The fuel cell system according to claim 1, a fuel cell that supplies fuel gas and reforming water to generate power, an exhaust heat exchanger that exchanges heat between the exhaust of the fuel cell and a refrigerant, A communication portion capable of communicating the inside and the outside is provided at the top, and a refrigerant tank for storing the refrigerant to be supplied to the exhaust heat exchanger is circulated between the refrigerant tank and the exhaust heat exchanger. A pipe, and a heat recovery pump that circulates the refrigerant in the pipe, and the pipe has a length of a pipe portion on a delivery side through which the refrigerant flows from the refrigerant tank to the exhaust heat exchanger. It is set to be twice or more the shortest distance connecting the refrigerant tank and the exhaust heat exchanger.

  In the fuel cell system according to the first aspect, by supplying the fuel gas and the reforming water to the fuel cell, the fuel cell generates electric power and discharges high-temperature exhaust gas. The hot exhaust gas exchanges heat with the refrigerant in the exhaust heat exchanger. The refrigerant that performs heat exchange is stored in a refrigerant tank.

  By operating the heat recovery pump, the refrigerant in the refrigerant tank is heated by the exhaust heat exchanger and then returned to the refrigerant tank, thereby increasing the temperature of the refrigerant in the refrigerant tank. Further, the exhaust gas discharged from the fuel cell is cooled by the exhaust heat exchanger, so that the water vapor in the exhaust gas is condensed into water. This water is used for power generation of the fuel cell.

  In order to generate water in the exhaust heat exchanger, it is necessary to lower the temperature of the refrigerant supplied to the exhaust heat exchanger to some extent. In the fuel cell system according to the present embodiment, in the piping for circulating the refrigerant between the exhaust heat exchanger and the refrigerant tank, the length of the piping portion on the delivery side for flowing the refrigerant from the refrigerant tank to the exhaust heat exchanger is set as the refrigerant. Since it is set to be twice or more the shortest distance connecting the tank and the exhaust heat exchanger, the heat of the refrigerant can be radiated and cooled in the piping portion on the delivery side.

  That is, in the fuel cell system according to claim 1, the delivery-side piping portion set to at least twice the shortest distance connecting the refrigerant tank and the exhaust heat exchanger serves as a radiator. A radiator and a radiator fan required for the system are not required, and the system can be simplified and made compact.

  According to a second aspect of the present invention, in the fuel cell system according to the first aspect, at least a part of the piping portion on the delivery side is formed in a meandering shape, a spiral shape, or a spiral shape.

  In the fuel cell system according to the second aspect, by forming at least a part of the piping portion on the delivery side in a meandering shape, a spiral shape, or a spiral shape, a long piping can be accommodated in a small space.

  According to a third aspect of the present invention, in the fuel cell system according to the first or second aspect, a housing that houses the fuel cell, the exhaust heat exchanger, the refrigerant tank, the piping, and the heat recovery pump. A body, a vent opening for introducing outside air that allows the outside air to be introduced into the casing, and an exhaust ventilation fan that exhausts the air inside the casing to the outside.

  In the conventional fuel cell system, in order to improve the cooling efficiency of the refrigerant, a radiator fan that blows air to the radiator is required. However, in the fuel cell system according to claim 3, by operating the exhaust ventilation fan, The outside air is introduced from the outside air introduction ventilation port, and the introduced outside air is applied to the piping, whereby the cooling efficiency of the refrigerant can be improved. That is, the exhaust ventilation fan that exhausts hot air in the housing also serves as a radiator fan, so that the radiator fan is not required and the system can be simplified and made compact. Further, in the fuel cell system according to claim 3, since there is no radiator fan, no noise is generated due to the radiator fan.

  According to a fourth aspect of the present invention, there is provided a housing that houses the fuel cell, the exhaust heat exchanger, the refrigerant tank, the pipe, and the heat recovery pump; The external air introduction ventilation fan which blows air to the piping part of the sending side, and the exhaust vent which is formed in the housing and exhausts the air in the housing to the outside. Fuel cell system.

  In the fuel cell system according to the fourth aspect, the cooling efficiency of the refrigerant can be improved by operating the outside air introduction ventilation fan so that the introduced outside air is applied to the pipe. Moreover, the hot air in a housing | casing can be discharged | emitted from a ventilation port. That is, since the outside air introduction ventilation fan also serves as a radiator fan, the radiator fan is not required, and the system can be simplified and made compact. Further, in the fuel cell system according to the fourth aspect, since there is no radiator fan, no noise is generated due to the radiator fan.

  The invention according to claim 5 is the fuel cell system according to any one of claims 1 to 4, wherein the fuel cell, the exhaust heat exchanger, the refrigerant tank, the pipe, and the heat recovery are provided. A housing for storing the pump is provided, and the piping portion on the delivery side is in contact with the housing.

  In the fuel cell system according to the fifth aspect, the heat from the piping portion on the delivery side can be released into the casing and can be released outside the casing through the casing. Thereby, the cooling efficiency of a refrigerant | coolant can be improved compared with the case where the heat | fever from the piping part of a sending side is only discharge | released in a housing | casing.

  As described above, the fuel cell system of the present invention has an excellent effect that the radiator can be eliminated and the system can be simplified and made compact.

1 is a configuration diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. It is a perspective view which shows the structure of the principal part of a housing | casing. It is a block diagram which shows the structure of a fuel cell module. It is a perspective view which shows the structure of the principal part of the housing | casing of the fuel cell system which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the structure of the principal part of the housing | casing of the fuel cell system which concerns on the 3rd Embodiment of this invention. It is a perspective view which shows the structure of the principal part of the housing | casing of the fuel cell system which concerns on the 4th Embodiment of this invention.

[First Embodiment]
Hereinafter, a fuel cell system 10 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The fuel cell system 10 of this embodiment is applied to a house as an example.

  As shown in FIG. 1, the fuel cell system 10 of this embodiment includes two units, a fuel cell unit 12 with a refrigerant tank and a backup heat source unit 14 that is separate from the fuel cell unit 12 with a refrigerant tank. ing. As an example, the fuel cell unit 12 with a refrigerant tank and the backup heat source unit 14 can be installed on a veranda or the like on a foundation formed of outdoor concrete or the like.

(Configuration of fuel cell unit with refrigerant tank)
The fuel cell unit 12 with a refrigerant tank includes a power generation unit 17 that generates power and discharges exhaust gas, a refrigerant heating unit 19 that heats the refrigerant W2 with the exhaust gas, and heats clean water with the refrigerant W2. A water heating unit 21 is provided.

  A fuel cell module 18 that generates power by being supplied with city gas, air (oxygen), and reforming water W1, a fuel gas pipe 20 that supplies city gas to the fuel cell module 18, and fuel gas A desulfurizer 22 provided in an intermediate portion of the pipe 20 for removing sulfur compounds contained in city gas, a reforming water tank 24 for storing reforming water W1 to be supplied to the fuel cell module 18, and reforming of the reforming water tank 24. A liquid level sensor 24A for measuring the liquid level of the quality water W1, a reforming water supply pipe 26 for connecting the reforming water tank 24 and the fuel cell module 18, and the reforming water W1 in the reforming water tank 24 as the fuel cell. A reforming water pump 28 for supplying to the module 18, a wiring 66 for transmitting the power generated by the fuel cell module 18 to the outside, and an intermediate portion of the wiring 66, which converts DC power into AC power. Nbata 68, air blower 86 is an oxidizing gas pipe 88 or the like provided has been accommodated, the power generation unit 17 is configured to include these components.

  Further, inside the casing 16, there are a refrigerant tank 30 for storing the refrigerant W2, an exhaust heat exchanger 31 for exchanging heat between the exhaust gas discharged from the fuel cell module 18 and the refrigerant W2, and the fuel cell module 18. A first exhaust gas pipe 32 connecting the exhaust heat exchanger 31, a second exhaust gas pipe 34 for exhausting the exhaust gas that has passed through the exhaust heat exchanger 31 to the outside of the housing 16, and generated inside the exhaust heat exchanger 31. A drain pipe 35 for discharging the generated moisture (water in the exhaust gas aggregated inside the exhaust heat exchanger 31) to the reformed water tank 24, the bottom of the refrigerant tank 30, and the exhaust heat exchanger 31 are connected. The first delivery side pipe 36 for supplying the refrigerant W2 of the refrigerant tank 30 to the exhaust heat exchanger 31, the ceiling wall 30A of the refrigerant tank 30 and the exhaust heat exchanger 31 are connected, and pass through the exhaust heat exchanger 31. Refrigerant W2 A heat recovery pump 40 is provided that is provided in the first return side pipe 38 and the first delivery side pipe 36 for returning to the exhaust pipe 30 and sends out the refrigerant W2 of the refrigerant tank 30 to the exhaust heat exchanger 31 side. The refrigerant heating unit 19 is configured to include these components.

  In addition, the housing 16 is connected to an upper portion of the refrigerant tank 30 and an upper water heat exchanger 44 for exchanging heat between the refrigerant W2 of the refrigerant tank 30 and the external water supplied from the outside. And a second return side pipe 46 for returning the refrigerant W2 that has passed through the upper water heat exchanger 44 to the refrigerant tank 30, and a second return side pipe. 48, a preheating pump 50 for returning the refrigerant W2 to the refrigerant tank 30, an upper water supply pipe 52 for supplying upper water supplied from the outside (water supply) to the upper water heat exchanger 44, and an upper water supply pipe 52. The hot water branch pipe 54 branched from the intermediate part of the water, the hot water supply pipe 56 for discharging the hot water that has passed through the hot water heat exchanger 44, and the hot water pipe 56 branched from the intermediate part of the hot water supply pipe 56 and passed through the hot water heat exchanger 44. Hot water supply branch pipe 58 for supplying clean water to the refrigerant tank 30 A hot water supplied from the hot water supply pipe 56 and a hot water supplied from the hot water branch pipe 54 (cold water provided in the hot water supply pipe 58 and adjusting the amount of the supplied water supplied to the refrigerant tank 30 and cold water) ) And a water discharge pipe 64 for discharging clean water from the mixing valve 62 to the outside of the housing 16 are accommodated, and the clean water heating unit 21 includes these components. It is configured.

  Further, inside the housing 16 is housed a control device 70 for controlling various electrical components provided in the ventilation fan 140 and the fuel cell unit 12 with the refrigerant tank.

  A temperature sensor 65 that is connected to the control device 70 and measures the outside air temperature is provided outside the housing 16.

  In the present embodiment, water is used as the refrigerant W2 of the refrigerant tank 30. An opening 33 is formed in the ceiling wall 30A of the refrigerant tank 30 as an air hole that penetrates the inside and outside of the refrigerant tank 30 and allows air to enter and exit. In addition, the refrigerant tank 30 stores the refrigerant W2 so that a space is provided in the upper portion, and the refrigerant W2 overflows from the opening 33 even when the volume of the refrigerant W2 in the tank expands due to thermal expansion. The volume of the refrigerant W2 to be injected into the refrigerant tank 30 is determined so as not to come out.

  In the present embodiment, the path through which the refrigerant W2 circulates between the refrigerant tank 30 and the exhaust heat exchanger 31, that is, the first circulation path by the first delivery side pipe 36 and the first return side pipe 38. 118 is formed. A path for the refrigerant W2 between the refrigerant tank 30 and the water heat exchanger 44, that is, the second delivery side pipe 46 and the second return side pipe 48 form a second circulation path 120. A hot water supply path 121 is formed by the hot water supply pipe 56 and the water discharge pipe 64.

  As shown in FIG. 2, a partition wall 16 </ b> P is provided on the lower side of the inside of the housing 16 with a certain distance from the bottom wall 16 </ b> B. The refrigerant tank 30 is installed on the bottom wall 16B, and a partition wall 16P is arranged on the upper side of the other bottom wall 16B excluding the installation part of the refrigerant tank 30. In FIG. 2, the components other than the casing 16, the refrigerant tank 30, the first delivery side pipe 36, and the partition wall 16 </ b> P are not shown.

  In the present embodiment, a first delivery side pipe 36 having an intermediate portion meandering in a zigzag manner is disposed between the bottom wall 16B and the partition wall 16P. The overall length of the first delivery side pipe 36 is set to be twice or more the shortest distance between the refrigerant tank 30 and the water heat exchanger 44. The first delivery side pipe 36 is a metal pipe such as a copper pipe excellent in heat conduction. In addition, the 1st sending side piping 36 of this embodiment is supported in the state spaced apart from the bottom wall 16B by the columnar spacer which is not shown in figure attached to the bottom wall 16B.

  The side wall 16L of the housing 16 is formed with a ventilation port 142 that communicates the space between the bottom wall 16B and the partition wall 16P and the outside. Further, the housing 16 is provided with a ventilation fan 140 for discharging the air in the housing 16 to the outside on the upper side of the side wall 16R opposite to the side wall 16L. When the ventilation fan 140 is driven, air in the housing 16 is discharged and external air (outside air) is introduced into the housing 16 through the ventilation port 142. The introduced air passes through the space between the bottom wall 16B and the partition wall 16P in the housing 16, and is discharged to the outside by the ventilation fan 140. A space portion between the bottom wall 16B and the partition wall 16P is a passage for air introduced from the outside, and a first delivery side pipe 36 meandering in a zigzag manner is disposed in the passage passage for air. Therefore, the air introduced from the ventilation port 142 hits the first delivery side pipe 36. In addition to the ventilation port 142, another ventilation port for introducing outside air into the housing 16 may be further provided. Further, the ventilation fan 140 is not limited to the upper part of the side wall 16R, and may be provided in other parts. In the present embodiment, the ventilation fan 140 is the exhaust ventilation fan of the present invention, and the ventilation port 142 is the outside air introduction ventilation port of the present invention.

  As shown in FIG. 3, the fuel cell module 18 includes a reforming catalyst 72, a burner 74, and a fuel cell stack 76 as main components inside a casing 71.

  The reforming catalyst 72 is connected to the fuel gas pipe 20. The reforming catalyst 72 is supplied with the city gas from which the sulfur compound is adsorbed and removed by the desulfurizer 22 through the fuel gas pipe 20. The reforming catalyst 72 performs steam reforming of the supplied city gas (raw material gas) using the reformed water (condensed water) W1 supplied through the reformed water supply pipe 26.

  A stack exhaust gas pipe 80 to be described later is connected to the burner 74. The burner 74 burns burner gas (stack exhaust gas containing unreacted hydrogen gas) supplied through the stack exhaust gas pipe 80 and heats the reforming catalyst 72. In the reforming catalyst 72, fuel gas containing hydrogen gas is generated from the city gas (raw material gas) supplied from the desulfurizer 22. This fuel gas is supplied to a fuel electrode 78 of a fuel cell stack 76 described later through a fuel gas pipe 75.

  The fuel cell stack 76 is a solid oxide fuel cell stack, and has a plurality of stacked fuel cell cells 81 (only one is shown in FIG. 2). Each fuel cell 81 has an electrolyte layer 82, and a fuel electrode 78 and an air electrode 84 stacked on the front and back surfaces of the electrolyte layer 82.

  An oxidizing gas (air) is supplied to the air electrode 84 (cathode electrode) through an oxidizing gas pipe 88 provided with an air blower 86. In the air electrode 84, as shown by the following formula (1), oxygen and electrons in the oxidizing gas react to generate oxygen ions. The oxygen ions reach the fuel electrode 78 through the electrolyte layer 82.

(Air electrode reaction)
1 / 2O ₂ + 2e ⁻ → O ²⁻ (1)

  On the other hand, in the fuel electrode 78, as shown by the following formulas (2) and (3), oxygen ions that have passed through the electrolyte layer 82 react with hydrogen and carbon monoxide in the fuel gas, and water (water vapor). And carbon dioxide and electrons are generated. Electrons generated at the fuel electrode 78 reach the air electrode 84 through an external circuit. Then, the electrons move from the fuel electrode 78 to the air electrode 84 in this way, whereby electric power is generated in each fuel cell 81. Further, each fuel cell 81 generates heat with the above reaction during power generation.

(Fuel electrode reaction)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (2)
CO + O ²⁻ → CO ₂ + 2e ⁻ (3)

  The upstream side of the stack exhaust gas pipe 80 connected to the fuel cell stack 76 is branched into a fuel electrode exhaust gas pipe 90 and an air electrode exhaust gas pipe 92. The fuel electrode exhaust gas pipe 90 and the air electrode exhaust gas pipe 92 are divided into fuel electrodes. 78 and the air electrode 84, respectively. The fuel electrode exhaust gas discharged from the fuel electrode 78 and the air electrode exhaust gas discharged from the air electrode 84 are discharged through the fuel electrode exhaust gas tube 90 and the air electrode exhaust gas tube 92 and mixed in the stack exhaust gas tube 80. And the stack exhaust gas. This stack exhaust gas contains unreacted hydrogen gas contained in the fuel electrode exhaust gas, and is supplied to the burner 74 as burner gas as described above. The burner 74 is connected to a first exhaust pipe 32 that discharges the burner exhaust gas to the exhaust heat exchanger 31.

  The control device 70 is supplied with electric power from the inverter 68 and controls the reforming water pump 28, the heat recovery pump 40, the preheating pump 50, the auxiliary water valve 60, the mixing valve 62, and the like.

(Configuration of backup heat source unit)
The backup heat source unit 14 of the present embodiment is a latent heat recovery type heat source unit (generally also referred to as a latent heat recovery type gas water heater) that can further heat and discharge the hot water supplied from the fuel cell unit 12 with a refrigerant tank. ). The latent heat recovery type heat source device is a type of heat source device that improves the thermal efficiency by recovering latent heat in the exhaust gas by converting the water vapor in the exhaust gas of the burner 100 to water (condensed water). As shown in FIG. 1, the hot water from the secondary heat exchanger 91, the primary heat exchanger 94, and the fuel cell unit 12 with a refrigerant tank is secondarily placed inside the first casing 93 of the backup heat source unit 14. The heat exchanger 91, the pipe 96 supplied to the primary heat exchanger 94, the burner 100 as a heating device for heating the primary heat exchanger 94, the fuel gas pipe 102 for supplying fuel gas to the burner 100, and the heat exchanger 94 are passed through. A pipe 98 for discharging hot water, a branch pipe 104 connected in the middle of the pipe 96, a mixing valve 106 connected to the pipe 98, a pipe 108 for discharging hot water from the mixing valve 106, and the temperature of the discharged hot water. A temperature sensor 109, a control device 110, and the like are provided. The control device 110 controls electrical components such as a mixing valve 106 and a flow rate adjustment valve (not shown) of fuel gas sent to the burner 100.

  Below the backup heat source unit 14, a drainage receptacle 128 is provided as a drainage facility for collecting drainage (condensate) and draining it to sewage or the like. The wastewater that has flowed into the drainage receptacle 128 can be discharged into sewage or the like.

  In this embodiment, when drainage (condensate) is discharged from the backup heat source unit 14, the drainage can be drained to the drain receiver 128 via the drain pipe 129.

  The reformed water tank 24 of the present embodiment is provided with a liquid level sensor 24A, and the liquid level of the reformed water W1 stored in the reformed water tank 24 has reached a preset upper limit value. When detected by the surface level sensor 24A, the control device 123 is able to recognize that the liquid level of the reforming water W1 stored in the reforming water tank 24 has reached a preset upper limit value.

  Further, the reforming water tank 24 of the present embodiment is connected to a drain pipe 130 having a drain pump 132 in the middle, and when the drain pump 132 is driven, the reforming water in the reforming water tank 24 is. W1 is discharged to the drain receiver 128 through the drain pipe 130. As an example, when the control device 123 determines that the liquid level of the reforming water W1 has reached a preset upper limit value, the control device 123 drives the drain pump 132 and stores the liquid level of the reforming water W1 stored in the reforming water tank 24. The drainage pump 132 is controlled so as to stop the drainage pump 132 when becomes a preset lower limit value. As a result, surplus reforming water W1 is drained to the drain receiver 128, and the amount of reforming water W1 necessary for power generation remains.

  The control of the drain pump 132 by the control device 123 is not limited to the example described above. For example, when the liquid level sensor 24A detects that the liquid level of the reforming water W1 stored in the reforming water tank 24 has reached a preset upper limit value, the control device 123 causes the drain pump 132 to remain at a certain time. It may be driven to discharge a certain amount of the reforming water W1 to the drain receiver 128. In this case, instead of the liquid level sensor 24A, an upper limit detection float switch that is switched on when the liquid level of the reforming water W1 reaches a preset upper limit value can be used. In addition, the upper limit value of the float switch for detecting the upper limit value of the reforming water W1 and the lower limit detection float switch for detecting the lower limit value of the reforming water W1 are used. Is detected by the upper limit detection float switch, the control device 123 causes the drainage pump until the lower limit detection float switch detects that the level of the reforming water W1 has reached the lower limit value. 132 may be driven to discharge a certain amount of the reformed water W1 to the drain receiver 128.

A city gas gas supply pipe 112 is connected to the fuel gas pipe 20 of the fuel cell unit 12 with refrigerant tank and the fuel gas pipe 102 of the backup heat source unit 14.
Further, the clean water discharge pipe 64 of the fuel cell unit 12 with the refrigerant tank and the pipe 96 of the backup heat source unit 14 are connected by a connection pipe 114. Furthermore, a pipe 116 for feeding hot water toward a water device in a house is connected to the pipe 108 of the backup heat source unit 14.

(Function, effect)
Next, the operation of the fuel cell system 10 of the present embodiment will be described.
In the fuel cell system 10 according to the first embodiment, the fuel gas is supplied from the reforming catalyst 72 to the fuel electrode 78 of the fuel cell stack 76, and the air blower 86 is activated to generate the oxidizing gas from the oxidizing gas pipe 88. When air is supplied to the air electrode 84 of the fuel cell stack 76, the fuel gas and the oxidizing gas react in the fuel cell stack 76 to generate power.

  Along with this power generation, stack exhaust gas containing unreacted hydrogen gas is discharged from the fuel cell stack 76, and this stack exhaust gas is burned by the burner 74 as burner gas, and the burner exhaust gas is discharged from this burner 74. . The burner exhaust gas contains water vapor and is supplied to the exhaust heat exchanger 31 through the first exhaust gas pipe 32.

  In the exhaust heat exchanger 31, heat is exchanged between the burner exhaust gas and the refrigerant W2 supplied from the refrigerant tank 30, and the refrigerant W2 is heated and the water vapor contained in the burner exhaust gas is condensed. The condensed water (distilled water) generated in this way is recovered in the reforming water tank 24 as the reforming water W1, and the reforming water recovered in the reforming water tank 24 is supplied to the reforming water supply pipe 26. Is supplied to the reforming catalyst 72 and is used as steam for steam reforming by the reforming catalyst 72. The burner exhaust gas from which moisture has been removed in this way is discharged to the outside through the second exhaust gas pipe 34.

  By operating the heat recovery pump 40, the first circulation path 118 circulates the refrigerant W2 between the refrigerant tank 30 and the exhaust heat exchanger 31, so that the lower refrigerant W2 in the refrigerant tank 30 is the first refrigerant W2. 1 is supplied to the exhaust heat exchanger 31 via the delivery pipe 36 and heated by the exhaust heat exchanger 31, and then returns to the upper side of the refrigerant tank 30, whereby the temperature of the refrigerant W2 in the refrigerant tank is increased from the upper side. Gradually rise toward the bottom.

  In the fuel cell system 10 of the present embodiment, the water used for power generation is recovered from the burner exhaust gas containing water vapor, so that the exhaust gas heat exchanger 31 cools the burner exhaust gas. In order to recover a sufficient amount of water, it is necessary to cool the burner exhaust gas to a certain temperature or lower, that is, the temperature of the refrigerant W2 supplied to the exhaust heat exchanger 31 is made lower than the certain temperature. It is preferable to keep it.

  In the fuel cell system 10 of the present embodiment, the intermediate portion of the first delivery side pipe 36 is formed in a zigzag shape that is an example of a meandering shape to increase the overall length and promote heat dissipation from the first delivery side pipe 36. can do. Therefore, even if there is no radiator, the temperature of the refrigerant W2 supplied to the exhaust heat exchanger 31 can be reduced, and a sufficient amount of the reforming water W1 used for power generation can be obtained.

  Since the first delivery side pipe 36 is formed in a zigzag shape and has a long overall length, a long pipe can be accommodated in a small space as compared with a case where the first delivery side pipe 36 is linear and has a long overall length.

  In addition, the ventilation fan 140 exhausts the hot air in the housing 16 to the outside, and the cold outside air that has flowed in from the ventilation port 142 can be applied to the first delivery side pipe 36. Therefore, heat radiation is promoted even without a radiator fan. Thus, the temperature of the refrigerant W2 can be efficiently reduced.

  Thus, in the fuel cell system 10 of the present embodiment, since there is no radiator or radiator fan required in the conventional fuel cell system, the system can be simplified and made more compact than before, and the cost can be reduced. It becomes possible. Further, since there is no radiator fan, there is no generation of noise due to the radiator fan.

  Furthermore, in the present embodiment, since the intermediate portion of the first delivery side pipe 36 is formed in a zigzag shape, the first delivery side pipe 36 having a long overall length can be stored in a small space, thus saving space. .

  The backup heat source unit 14 is connected to the fuel tank unit 12 with the refrigerant tank when, for example, the temperature of the refrigerant W2 in the refrigerant tank 30 is low and the temperature of the clean water discharged from the clean water heat exchanger 44 is low. The supplied clean water can be further heated. Further, the backup heat source unit 14 can be operated when additionally cooking a bath in a house (not shown).

[Second Embodiment]
Next, a fuel cell system 10 according to a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  In the first embodiment, the ventilation port 142 is formed in the side wall 16L of the casing 16, and the ventilation fan 140 is provided in the opposite side wall 16R. However, as shown in FIG. In the system 10, the positional relationship between the ventilation port 142 and the ventilation fan 140 is reversed with respect to the fuel cell system 10 of the first embodiment.

  In the fuel cell system 10 of the present embodiment, by operating the ventilation fan 140, the introduced outside air is applied to the first delivery side pipe 36, whereby the cooling efficiency of the refrigerant W2 can be improved. Further, hot air in the housing 16 can be discharged from the ventilation port 142. In the present embodiment, the ventilation fan 140 is the outside air introduction ventilation fan of the present invention, and the ventilation port 142 is the exhaust ventilation port of the present invention. In this embodiment, since the ventilation fan 140 also serves as a radiator fan, the radiator fan is not required, and the system can be simplified and made compact. Further, as in the first embodiment, since there is no radiator fan, there is no generation of noise due to the radiator fan.

[Third Embodiment]
Next, a fuel cell system 10 according to a third embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  In the first embodiment, the first delivery side pipe 36 meandering in a zigzag manner is disposed between the bottom wall 16B and the partition wall 16P. However, in the fuel cell system 10 of the present embodiment, as shown in FIG. In addition, the entire length of the first delivery side pipe 36 is set long by forming an intermediate portion of the first delivery side pipe 36 in a spiral shape between the bottom wall 16B and the partition wall 16P. In the present embodiment as well, similarly to the first embodiment, since the heat can be radiated from the first delivery side pipe 36 by increasing the total length of the first delivery side pipe 36, a radiator or a radiator fan is required. And not. Also in the present embodiment, as in the first embodiment, the first delivery side pipe 36 having a long overall length can be accommodated in a small space, thereby saving space.

[Fourth Embodiment]
Next, a fuel cell system 10 according to a fourth embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.

  In the first embodiment, the first delivery side pipe 36 is disposed between the bottom wall 16B and the partition wall 16P. However, in the fuel cell system 10 of the present embodiment, as shown in FIG. By forming the side pipe 36 on the outer peripheral side of the refrigerant tank 30 so as to be spaced apart from the refrigerant tank 30 and forming a spiral, the overall length of the first delivery side pipe 36 is set long while saving space.

  In the present embodiment, since the first delivery side pipe 36 is arranged in the vertical direction, the air around the first delivery side pipe 36 is warmed by the warmed first delivery side pipe 36 so that the inside of the housing Thus, natural convection occurs, and the release of heat can be promoted by natural convection of the air in the housing 16. In order to further promote the release of heat, measures such as attaching fins to the first delivery side pipe 36 may be taken. Also in this embodiment, since heat can be radiated from the first delivery side pipe 36, a radiator and a radiator fan are not required.

[Fifth Embodiment]
Next, a fuel cell system 10 according to a fifth embodiment of the present invention will be described.
The fuel cell system 10 of this embodiment is a modification of the fuel cell system 10 of the first embodiment. Although illustration is omitted, in the fuel cell system 10 of the present embodiment, the first delivery side pipe 36 is brought into contact with the bottom wall 16B of the casing 16 and the heat of the refrigerant W2 is transferred to the casing 16 via the casing 16. It can be released to the outside.

  In the present embodiment, heat from the first delivery side pipe 36 can be released into the housing 16 and can be released to the outside of the housing 16 via the housing 16. The cooling efficiency of the refrigerant W2 can be improved as compared with the case where the heat from the housing is simply released into the housing 16.

  In the present embodiment, the first delivery side pipe 36 is brought into contact with the bottom wall 16B of the housing 16, but may be brought into contact with other wall surfaces of the housing 16 or may be brought into contact with a plurality of wall surfaces. Good. Further, in consideration of the influence of solar radiation, the first delivery side pipe 36 may be brought into contact with the back surface of the housing 16 where sunlight does not hit.

[Other Embodiments]
Although an example of the present invention has been described above, the present invention is not limited to the above, and it is needless to say that various modifications can be made without departing from the spirit of the present invention. .
For example, you may combine 1st Embodiment-4th Embodiment suitably as needed.

  In the above-described embodiment, an example in which city gas is used as the fuel gas supplied to the fuel cell stack 76 is shown, but flammable gas other than city gas such as propane gas may be used as the fuel gas.

DESCRIPTION OF SYMBOLS 10 Fuel cell system 16 Housing | casing 30 Refrigerant tank 31 Exhaust heat exchanger 36 1st delivery side piping (piping part of delivery side)
38 First return piping (piping)
40 heat recovery pump W1 reformed water 81 fuel cell (fuel cell)
140 Ventilation fan (exhaust ventilation fan, outside air introduction ventilation fan)
142 Ventilation openings (Ventilation openings for introducing outside air, ventilation openings for exhaust)

Claims (5)

A fuel cell that generates power by supplying fuel gas and reformed water; and
An exhaust heat exchanger for exchanging heat between the exhaust of the fuel cell and the refrigerant;
A refrigerant tank for storing the refrigerant to be supplied to the exhaust heat exchanger;
Piping for circulating the refrigerant between the refrigerant tank and the exhaust heat exchanger;
A heat recovery pump for circulating the refrigerant through the pipe;
Have
In the pipe, the length of the pipe portion on the delivery side for flowing the refrigerant from the refrigerant tank to the exhaust heat exchanger is set to be at least twice the shortest distance connecting the refrigerant tank and the exhaust heat exchanger. The fuel cell system.   2. The fuel cell system according to claim 1, wherein at least a part of the piping portion on the delivery side is formed in a meandering shape, a spiral shape, or a spiral shape. A housing for housing the fuel cell, the exhaust heat exchanger, the refrigerant tank, the pipe, and the heat recovery pump;
A ventilation opening for introducing outside air that is formed in the casing and allows outside air to be introduced into the casing;
An exhaust ventilation fan for exhausting the air in the housing to the outside;
The fuel cell system according to claim 1 or 2, comprising: A housing for housing the fuel cell, the exhaust heat exchanger, the refrigerant tank, the pipe, and the heat recovery pump;
An outside air introduction ventilation fan which introduces outside air into the air in the housing and blows air to the piping part on the delivery side;
An exhaust vent formed in the housing for exhausting air in the housing to the outside;
The fuel cell system according to claim 1 or 2, comprising: A housing for housing the fuel cell, the exhaust heat exchanger, the refrigerant tank, the pipe, and the heat recovery pump;
The fuel cell system according to any one of claims 1 to 4, wherein the delivery-side piping portion is in contact with the housing.