JP2007115715A - Fuel cell power generating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover heat, without making the path for a heat exchange medium complex. <P>SOLUTION: Since electrochemical reaction of fuel gas and oxidizing gas in a fuel cell 40 is heat generation reaction in a fuel cell power generation system 10, both anode-off gas and cathode-off gas have heat. A circulation pump 51 circulates water or hot water which is the heat exchange medium 54 in a heat exchange medium circulation path 50, in which water or hot water returns into a hot-water storage tank 52 via an anode-off gas heat exchanger 42 and a cathode-off gas heat exchanger 44 arranged in series from the hot-water storage tank 52. Consequently, the heat exchange media 54, having the same origin, recover heat from the anode-off gas and the cathode-off gas, so heat recovery is performed efficiently. Moreover, since the heat exchange medium 54 is circulated in the heat exchange medium circulation path 50 in which both the heat exchangers 42, 44 are arranged in series, the path for the heat exchange medium 54 will not become complex. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a fuel cell power generation system.

  In recent years, a power generation system incorporating a fuel cell has been proposed as a cogeneration system in consideration of environmental problems. As this fuel cell, a cell constructed by stacking a plurality of single cells is known. As a single cell, an electrolyte membrane, an anode and a cathode sandwiching the electrolyte membrane, and fuel gas are supplied to the anode. In addition, a device is known that includes an oxidant gas supplied to the cathode and a separator that forms a partition wall between adjacent single cells. As a fuel gas, a fuel gas that uses a hydrogen-rich gas obtained by a reaction between a hydrocarbon fuel and water in a fuel gas generator heated by a burner or the like is known.

  By the way, in the fuel cell power generation system, in order to effectively utilize the anode off gas discharged from the anode of the fuel cell and the cathode off gas discharged from the cathode, a burner for heating the fuel gas generator with the anode off gas and the cathode off gas. The ones that supply are known. For example, in Japanese Patent Laid-Open No. 6-188016, the anode off gas is supplied to a burner that heats the fuel gas generator after the moisture in the anode off gas is condensed by the anode off gas condenser, and the cathode off gas is condensed to the cathode off gas. After the moisture in the anode off gas is condensed by the vessel, the fuel gas generator is supplied to the burner that heats it.

  However, in the above-mentioned publication, the heat exchange medium that exchanges heat with the anode offgas in the anode offgas condenser and the heat exchange medium that exchanges heat with the cathode offgas in the cathode offgas condenser are supplied by what route. Is not considered. For this reason, the path | route of a heat exchange medium tends to become complicated, and the heat recovery suitable for a fuel cell power generation system cannot be performed.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fuel cell power generation system capable of efficiently recovering heat without complicating the path of a heat exchange medium.

In order to achieve the above-described object, a fuel cell power generation system of the present invention includes:
A fuel cell that generates electricity by an electrochemical reaction between a fuel gas supplied to the anode and an oxidizing gas supplied to the cathode;
An anode offgas heat exchanging section for recovering heat of the anode offgas discharged from the anode by a heat exchange medium;
A cathode offgas heat exchanging section for recovering heat of the cathode offgas discharged from the cathode by the heat exchange medium;
A heat exchange medium reservoir for storing the heat exchange medium;
A heat exchange medium that circulates the heat exchange medium through a circulation path that returns to the heat exchange medium storage section through the anode offgas heat exchange section and the cathode offgas heat exchange section arranged in random order in series from the heat exchange medium storage section And a circulation part.

  In the fuel cell power generation system of the present invention, since the electrochemical reaction between the fuel gas and the oxidizing gas in the fuel cell is an exothermic reaction, both the anode off-gas and the cathode off-gas have heat. The heat exchange medium circulation unit circulates the heat exchange medium in a circulation path that returns to the heat exchange medium storage unit through the anode off-gas heat exchange unit and the cathode off-gas heat exchange unit arranged in random order in series from the heat exchange medium storage unit. The same source heat exchange medium recovers heat from the anode offgas in the anode offgas heat exchanger and also recovers heat from the cathode offgas in the cathode offgas heat exchanger. Thus, since the heat exchange medium is circulated through the circulation path in which the anode offgas heat exchange section and the cathode offgas heat exchange section are arranged in series in random order, the path of the heat exchange medium is not complicated. Moreover, since the same heat exchange medium at the source recovers the heat of the anode offgas and the heat of the cathode offgas, heat recovery can be performed efficiently.

  The fuel cell power generation system of the present invention includes a fuel gas generation unit that supplies a hydrogen-rich gas obtained by a reaction between a hydrocarbon-based fuel and water to the anode as the fuel gas, and the combustion gas is used to burn the gas. A combustion part that heats the fuel gas generation part, and the anode off gas heat exchange part also has a function of a condenser, and the anode off gas after recovering heat and condensed water by the heat exchange medium is used as the combustion gas. May be supplied to the combustion section. Here, in order to promote the reaction between the hydrocarbon-based fuel and water in the fuel gas generation unit, the fuel gas generation unit is heated by burning the combustion gas in the combustion unit. As described above, the anode off gas after the heat and condensed water are recovered by the heat exchange medium in the anode off gas heat exchange section is effectively used. In addition, since the condensed water is recovered and the humidity of the anode off gas is reduced, problems such as misfire and damage are unlikely to occur in the combustion part.

  The fuel cell system of the present invention includes the fuel gas generation unit and the combustion unit, and the anode offgas after the anode offgas heat exchange unit has recovered heat and condensed water by the heat exchange medium as the combustion gas. When supplying to the combustion section, the anode offgas heat exchange section may be arranged upstream of the cathode offgas heat exchange section in the circulation path. By so doing, it is possible to preferentially obtain the effect of reducing the humidity of the anode off-gas supplied to the combustion section and making it difficult to cause problems in the combustion section. Further, the anode off-gas heat exchanging section may be arranged in the most upstream in the circulation path, and in this way, the effect of making it difficult to cause a malfunction of the combustion section can be given the highest priority.

  In the fuel cell power generation system of the present invention, the cathode offgas also has a condenser function in a fuel gas generation unit that supplies a hydrogen-rich gas obtained by a reaction between a hydrocarbon-based fuel and water as the fuel gas to the anode. You may provide the condensed water supply part supplied in order to make the high purity water obtained by condensing the water | moisture content in cathode offgas in a heat exchange part react with the said hydrocarbon fuel. In this way, high-purity water obtained from the cathode off gas can be used effectively. The condensed water supply unit supplies high-purity water obtained by condensing moisture in the anode offgas in the anode offgas heat exchange unit to the fuel gas generation unit in order to react with the hydrocarbon fuel. In this case, high-purity water obtained from the anode off gas can also be used effectively. Since water is generated on the cathode side by the electrochemical reaction of the fuel cell, more high-purity water can be obtained from the cathode offgas than the anode offgas.

  When the fuel cell power generation system of the present invention includes the condensed water supply unit, the fuel cell power generation system further includes a water purification unit that purifies tap water, and the water purification unit supplies the high-purity water supplied to the fuel gas generation unit. May be supplied to the condensed water supply unit. In this case, when the supply of the high purity water to the fuel gas generation unit by the condensed water supply unit is insufficient, the water purification unit, which is a consumable item, is operated. Compared with the case where it supplies, the use frequency of a water refinement | purification part needs to be less, and the lifetime of a water refinement | purification part becomes long.

  The fuel cell power generation system of the present invention includes a condensed water purification unit that purifies water obtained by condensing water in the cathode offgas in the cathode offgas heat exchange unit that also functions as a condenser, a hydrocarbon-based fuel, and water The hydrogen-rich gas obtained by the reaction with the fuel is supplied to the anode as a fuel gas to supply the purified water purified by the condensed water purification unit to the hydrocarbon fuel. And a purified water supply unit. In this way, water obtained from the cathode off-gas can be effectively used after being purified. The condensed water purification unit may also purify water obtained by condensing moisture in the anode offgas in the anode offgas heat exchange unit. In this way, water obtained from the anode off-gas can also be used effectively after purification. In the condensate purification unit, it is usually less burdensome to purify water obtained from cathode offgas or anode offgas than to purify tap water.

  In the fuel cell system of the present invention, the heat exchange medium may be water or hot water, and the heat exchange medium reservoir may be a hot water storage tank. In this way, the heat generated in this system can be recovered as hot water, which is highly useful.

  In the fuel cell system of the present invention, the circulation path recovers the heat of the combustion part exhaust gas discharged from the combustion part downstream of the anode offgas heat exchange part and the cathode offgas heat exchange part by the heat exchange medium. A combustion part exhaust gas heat exchange part may be arranged. By doing so, the same heat exchange medium at the source recovers not only the heat of the anode offgas and the heat of the cathode offgas, but also the heat of the exhaust gas from the combustion section, so that the entire system can be efficiently recovered.

  In the fuel cell system of the present invention, the circulation path is a cooling medium that recovers the heat of the cooling medium that cools the fuel cell by the heat exchange medium downstream of the anode offgas heat exchange unit and the cathode offgas heat exchange unit. A heat exchange part may be arranged. In this way, the same heat exchange medium at the source recovers the heat of the cooling medium heated by cooling the fuel cell in addition to the heat of the anode offgas and the cathode offgas, so that the entire system can recover heat efficiently. It can be performed. At this time, in the circulation path, the cooling medium heat exchanging unit may be arranged on the most downstream side. Usually, the temperature of the cooling medium for cooling the fuel cell is higher than that of the anode off-gas and the cathode off-gas, so heat is recovered from the cooling medium even if it is a heat exchange medium after recovering heat from these off-gas and increasing the temperature. Therefore, the entire system can efficiently recover heat.

  Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of the configuration of the fuel cell power generation system 10. This fuel cell power generation system 10 mainly includes a reformer 30 that reforms city gas into hydrogen-rich reformed gas, and a CO selective oxidation unit 34 that reduces carbon monoxide in the reformed gas and uses it as fuel gas. A fuel cell 40 that generates electric power by an electrochemical reaction between the fuel gas and the oxidizing gas, an anode offgas heat exchanger 42 that recovers the heat of the anode offgas discharged from the fuel cell 40, and a cathode offgas discharged from the fuel cell. Through a heat exchanger 42, 44, 45, 46 in which water or hot water as a heat exchange medium 54 stored in the hot water storage tank 52 is arranged in series from the hot water storage tank 52. A circulation pump 51 that circulates the heat exchange medium 54 in a heat exchange medium circulation path 50 that returns to the hot water storage tank 52 is provided. In addition, the white arrow in FIG. 1 represents the flow of the heat exchange medium 54 which distribute | circulates the circulation path 50, [1] and [1], [2] and [2], [3] and [3] are respectively It shall be connected.

  The reformer 30 supplies the mixture of the city gas and steam introduced from the mixer 28 to the steam reforming reaction and shift reaction of the following equations (1) and (2), thereby improving the hydrogen-rich reforming. Generates quality gas. The reformer 30 is provided with a combustion section 32 that supplies heat necessary for such a reaction. The combustion section 32 is supplied with city gas from the gas pipe 22 and with air necessary for combustion. Further, the anode off-gas after passing through the anode off-gas heat exchanger 42 is piped so as to be supplied. That is, in order to effectively use the anode off gas, unreacted hydrogen in the anode off gas can be used as the fuel of the combustion unit 32.

[Equation 1]
CH4 + H2O → CO + 3H2 (1)
CO + H2O → CO2 + H2 (2)

  The mixer 28 mixes the city gas from which the sulfur content has been removed by the desulfurizer 24 from the gas pipe 22 and the steam obtained by evaporating the water from the water tank 26 in the evaporator 27 at an appropriate ratio, thereby reforming. To the vessel 30. Purified water is supplied to the water tank 26 from a water purifier 25 that purifies and purifies tap water, and condensed water is supplied from an anode offgas heat exchanger 42 and a cathode offgas heat exchanger 44. ing.

  The CO selective oxidation unit 34 is modified by a carbon monoxide selective oxidation catalyst (for example, a catalyst made of an alloy of platinum and ruthenium) that receives supply of air from a pipe (not shown) and selects and oxidizes carbon monoxide in the presence of hydrogen. Carbon monoxide in the gas is selectively oxidized to obtain a hydrogen-rich fuel gas having a very low carbon monoxide concentration (about several ppm in this embodiment). Note that the reformer 30 and the CO selective oxidation unit 34 of the present embodiment correspond to a fuel gas generation unit of the present invention.

  The fuel cell 40 is configured as a solid polymer fuel cell in which a plurality of single cells 410 (see FIG. 2) are stacked. The single cell 410 includes an electrolyte membrane 412 and the electrolyte membrane 412 as shown in FIG. A separator having an anode 414 and a cathode 416 sandwiching the electrolyte membrane 412, a separator 418 having a fuel gas supply path 415 for supplying fuel gas to the anode 414, and an oxidizing gas supply path 417 for supplying oxidizing gas to the cathode 416 is provided. The separators 418 and 420 form a partition wall with the adjacent single cell 410. The anode 414 includes a catalyst electrode 414a and a gas diffusion electrode 414b, and the cathode 416 includes a catalyst electrode 416a and a gas diffusion electrode 416b. The fuel gas is supplied from the CO selective oxidation unit 34 to the anode 414 of each unit cell 410, and the air as the oxidizing gas is supplied from the blower 41 to the cathode 416 of each unit cell 410. Power is generated by an electrochemical reaction between hydrogen in the atmosphere and oxygen in the oxidizing gas. An output terminal (not shown) of the fuel cell 40 is connected to the outside via an inverter 49, and DC power from the fuel cell 40 is converted into AC power and supplied to a load (not shown).

  In the heat exchange medium circulation path 50, the heat exchange medium 54 stored in the hot water tank 52 is transferred from the hot water tank 52 to the anode offgas heat exchanger 42, the cathode offgas heat exchanger 44, the combustion exhaust gas heat exchanger 45, and the cooling water heat exchange. The circulation path is such that after passing through the vessel 46 in this order, it returns to the hot water tank 52 again. The circulation pump 51 corresponds to the heat exchange medium circulation section of the present invention, is provided in the middle of the heat exchange medium circulation path 50, and circulates the heat exchange medium 54 from the hot water tank 52 to the heat exchange medium circulation path 50. . Hot water as the heat exchange medium 54 stored in the hot water storage tank 52 is supplied to a predetermined location through a hot water supply path (not shown), and hot water is supplied to the hot water storage tank 52 so that the hot water storage tank 52 is full. The

  At the time of start-up (immediately after the start of operation), the anode off-gas heat exchanger 42 is sent from the CO selective oxidation unit 34 because the valve 61 and the valve 63 are opened and the valve 62 and the valve 64 are closed by a control device (not shown). Heat exchange is performed between the initial fuel gas and the heat exchange medium 54 passing through the heat exchange medium circulation path 50. In the anode off-gas heat exchanger 42, the heat exchange medium 54 recovers heat by depriving the initial condensation latent heat of the fuel gas, and the fuel gas condenses moisture and dehumidifies by depriving the latent condensation heat. The anode offgas heat exchanger 42 supplies the fuel gas after the heat exchange to the initial offgas combustor 57. The fuel gas sent to the initial off-gas combustor 57 undergoes catalytic combustion in the initial off-gas combustor 57 and is then discharged to the outside through the initial off-gas heat exchanger 58. Thus, since the fuel gas with reduced humidity is sent to the initial off-gas combustor 57, the function of the initial off-gas combustor 57 that performs catalytic combustion is maintained, and defects such as damage are less likely to occur. The initial off-gas heat exchanger 58 and the initial off-gas combustor 57 are incorporated in the cooling water circulation path 43, and the cooling water after passing through the fuel cell 40 causes the initial off-gas heat exchanger 58 and the initial off-gas combustor 57 to pass through this. Pass in order.

  On the other hand, in the anode off gas heat exchanger 42, the valve 61 and the valve 63 are closed and the valve 62 and the valve 64 are opened by a control device (not shown) during steady operation, so the CO selective oxidation unit 34 to the anode 414 of the fuel cell 40. Heat exchange is performed between the anode off-gas discharged via the heat exchange medium 54 and the heat exchange medium 54 passing through the heat exchange medium circulation path 50. In the anode off-gas heat exchanger 42, the heat exchange medium 54 recovers heat by depriving the condensation latent heat of the anode off-gas, and the anode off-gas condenses moisture and dehumidifies by depriving the condensation latent heat. The anode offgas heat exchanger 42 supplies the anode offgas after heat exchange to the combustion unit 32 and supplies condensed water obtained by condensing moisture in the anode offgas to the water tank 26.

  The cathode offgas heat exchanger 44 exchanges heat between the cathode offgas discharged from the cathode 416 of the fuel cell 40 and the heat exchange medium 54 that passes through the heat exchange medium circulation path 50. In the cathode offgas heat exchanger 44, the heat exchange medium 54 recovers heat by depriving the latent heat of condensation of the cathode offgas, and the cathode offgas condenses moisture by depriving the latent heat of condensation. The cathode offgas heat exchanger 44 discharges the cathode offgas after heat exchange to the atmosphere, and supplies condensed water obtained by condensing moisture in the cathode offgas to the water tank 26.

  The combustion exhaust gas heat exchanger 45 performs heat exchange between the combustion exhaust gas generated in the combustion unit 32 and the heat exchange medium 54 that passes through the heat exchange medium circulation path 50. In the combustion exhaust gas heat exchanger 45, the heat exchange medium 54 takes heat from the combustion exhaust gas and recovers it. The combustion exhaust gas means that the anode off gas after passing through the city gas or the anode off gas heat exchanger 42 and oxygen in the air burn and pass through a jacket (not shown) provided so as to surround the reformer 30. This is the gas that is discharged.

  The cooling water heat exchanger 46 is provided in the middle of the cooling water circulation path 43. Here, the cooling water circulation path 43 is configured so that the cooling water stored in the reservoir tank 47 by the circulation pump 48 passes through the cooling water passage (not shown) of the fuel cell 40 from the reservoir tank 47 and then the initial off-gas heat exchanger 58 and the initial off-gas combustion. This is a circulation path that passes through a cooling water passage (not shown) of the vessel 57 and the cooling water heat exchanger 46 in this order and returns to the reservoir tank 47 again. However, a bypass path provided with a cooler 55 that performs forced cooling by a fan is provided between the coolant heat exchanger 46 and the reservoir tank 47 in the coolant circulation path 43, and the coolant is set in advance. When the temperature does not exceed, the thermostat 56 provided at the branch point of the bypass path does not operate, and the cooling water is immediately led from the cooling water heat exchanger 46 to the reservoir tank 47, whereas when the cooling water exceeds the predetermined temperature, the thermostat 56 is operated, and the cooling water is led to the bypass path and forcedly cooled by the cooler 55 and then led to the reservoir tank 47. The cooling water heat exchanger 46 heats between the cooling water after passing through the fuel cell 40, the initial off-gas heat exchanger 58 and the initial off-gas combustor 57 and the heat exchange medium 54 passing through the heat exchange medium circulation path 50. Exchange. Although the electrochemical reaction in the fuel cell 40 is an exothermic reaction, the fuel cell 40 is maintained at an appropriate temperature (80 to 90 ° C. in this embodiment) by circulating the cooling water in this way.

  Next, heat recovery and high-purity water recovery during steady operation in the fuel cell power generation system 10 configured as described above will be described. In the fuel cell power generation system 10, the heat exchange medium 54 of the hot water storage tank 52 circulates through the heat exchange medium circulation path 50 by driving the circulation pump 51.

  First, the heat exchange medium 54 is sent from below the hot water tank 52 to the anode offgas heat exchanger 42, and the anode offgas heat exchanger 42 collects condensation latent heat of the anode offgas. On the other hand, the anode off-gas is burned in the combustion section 32 for heating the reformer 30 after moisture in the anode off-gas is condensed and dehumidified by depriving the latent heat of condensation. There is no problem such as misfire or damage in the combustion section 32. In addition, since the condensed water obtained here is relatively high-purity water, it is sent to the water tank 26 and is effectively used as water to be reacted with the city gas in the reformer 30.

  Next, the heat exchange medium 54 that has passed through the anode offgas heat exchanger 42 is sent to the cathode offgas heat exchanger 44, and the cathode offgas heat exchanger 44 collects the latent heat of condensation of the cathode offgas. On the other hand, in the cathode off gas, moisture in the cathode off gas is condensed by being deprived of the latent heat of condensation. In addition, since a large amount of water is generated on the cathode side by the electrochemical reaction in the fuel cell 40, the cathode offgas discharged from the cathode contains a large amount of water. For this reason, a large amount of condensed water is generated from the cathode offgas heat exchanger 44. And since the condensed water obtained here is high-purity water, it is sent to the water tank 26 and is effectively used as water to react with the city gas in the reformer 30. The water tank 26 is supplied with condensed water generated in the anode off-gas heat exchanger 42 and a large amount of condensed water generated in the cathode off-gas heat exchanger 44. For the shortage, the valve 29 is opened to open the water purifier. Supplement with purified water from 25. The opening / closing control of the valve 29 is performed by a control device (not shown).

  Subsequently, the heat exchange medium 54 that has passed through the cathode offgas heat exchanger 44 is sent to the combustion exhaust gas heat exchanger 45, and the combustion exhaust gas heat exchanger 45 recovers the heat of the combustion exhaust gas. Condensed water is also generated in the combustion exhaust gas heat exchanger 45, but the exhaust gas after combustion of city gas that has not been desulfurized also passes through the combustion exhaust gas heat exchanger 45. It is discharged without being supplied to the water tank 26 because it contains a minute.

  Finally, the heat exchange medium 54 that has passed through the combustion exhaust gas heat exchanger 45 is sent to the cooling water heat exchanger 46, and after collecting the heat of the cooling water in the cooling water heat exchanger 46, the hot water storage tank again. 52 is returned to above. The temperature of the cooling water supplied to the cooling water heat exchanger 46 is 70 to 80 ° C. in this embodiment, and is introduced into the anode off gas introduced into the anode off gas heat exchanger 42 or the cathode off gas heat exchanger 44. The temperature is higher than the cathode off gas and the combustion exhaust gas introduced into the combustion exhaust gas heat exchanger 45. For this reason, even if it is the heat exchange medium 54 after heat | fever was collect | recovered with each heat exchanger 42,44,45, a heat | fever can be collect | recovered from cooling water in the cooling water heat exchanger 46. FIG.

  According to the fuel cell power generation system 10 of the present embodiment described in detail above, the heat exchange medium circulation path 50 is not complicated because the heat exchangers 42, 44, 45, and 46 are connected in series. Since the heat exchange medium 54 from the hot water storage tank 52 recovers the heat of the anode off gas and the heat of the cathode off gas, heat recovery can be performed efficiently. In particular, the present embodiment is highly useful because the collected heat is stored as hot water. Further, since the exhaust (heat) loss of the sensible heat of water vapor in the anode off-gas is reduced, the city gas supplied to the combustion unit 32 can be reduced, and the efficiency is improved.

  Further, the anode off-gas after passing through the anode off-gas heat exchanger 42 is supplied to the combustion unit 32. However, since this gas is reduced in humidity, problems such as misfire and damage are unlikely to occur in the combustion unit 32.

  Furthermore, since the condensed water obtained from the anode off-gas heat exchanger 42 and the condensed water obtained from the cathode off-gas heat exchanger 44 are both high-purity water, they should be effectively used for the steam reforming reaction in the reformer 30. Can do. Further, since the water purifier 25, which is a consumable, only needs to be operated when high-purity water in the water tank 26 is insufficient, the purified water is supplied to the steam reforming reaction in the reformer 30 only by the water purifier 25. Compared to the case, the frequency of use of the water purifier 25 can be reduced, and the life of the water purifier 25 becomes longer.

  Furthermore, since the anode off-gas heat exchanger 42 is disposed upstream of the cathode off-gas heat exchanger 44 in the heat exchange medium circulation path 50, the anode off-gas supplied to the combustion unit 32 is reduced in humidity and burned. Preventing the occurrence of defects in the section 32 can be prioritized over effectively using high-purity water obtained from the cathode offgas. Here, since the anode off-gas heat exchanger 42 is the most upstream, preventing the occurrence of problems in the combustion section 32 is the top priority.

  Further, in the heat exchange medium circulation path 50, a combustion exhaust gas heat exchanger 45 is disposed downstream of the anode offgas heat exchanger 42 and the cathode offgas heat exchanger 44, and a cooling water heat exchanger 46 is further disposed downstream. Since the heat exchange medium 54 from one hot water storage tank 52 collects not only the heat of the anode offgas and the heat of the cathode offgas, but also the heat of the exhaust gas from the combustion section and the heat of the cooling water of the fuel cell 40, As a whole, heat recovery can be performed efficiently.

  It should be noted that the present invention is not limited to the above-described embodiment, and can of course be implemented in various forms within the scope belonging to the technical scope of the present invention.

  For example, in the above-described embodiment, the air supplied from the blower 41 to the cathode 416 of the fuel cell 40 is preheated with the heat of the cathode offgas discharged from the cathode 416 of the fuel cell 40, and the cathode offgas is air. After the preheating, the cathode offgas heat exchanger 44 may be passed.

  In the above-described embodiment, the anode offgas heat exchanger 42 is provided upstream of the cathode offgas heat exchanger 44 in the heat exchange medium circulation path 50. Conversely, the cathode offgas heat exchanger 44 is connected to the anode offgas heat exchanger. It may be provided upstream of 42. In this way, the condensed water contained in the cathode off gas can be recovered more efficiently, and the burden on the water purifier 25 can be reduced.

  Furthermore, in the above-described embodiment, the condensed water obtained from the anode off gas in the anode off gas heat exchanger 42 and the condensed water obtained from the cathode off gas in the cathode off gas heat exchanger 44 are stored in the water tank 26 without purification. Although the configuration for supplying to the reformer 30 is employed, the configuration shown in FIG. 3 may be employed. In FIG. 3, the configuration is the same as that of FIG. 1 except for the path of water supplied to the reformer 30. That is, tap water appropriately replenished via the regulating valve 20, condensed water obtained from the anode off gas by the anode off gas heat exchanger 42, and condensed water obtained from the cathode off gas by the cathode off gas heat exchanger 44 are used as water. The water in the water tank 26 is stored in the tank 26, and the water in the water tank 26 is sent to the water purifier 25 filled with the ion exchange resin by the pump 21 for purification, and the purified water is reformed through the evaporator 27 and the like. A configuration of supplying to 30 may be adopted. This configuration is effective when impurities are eluted in the condensed water collected from each off gas.

It is a block diagram which shows the outline of a structure of the fuel cell power generation system which is one Embodiment of this invention. It is sectional drawing of the single cell which comprises a fuel cell. It is a block diagram which shows the outline of a structure of the fuel cell power generation system which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell power generation system, 22 ... Gas piping, 24 ... Desulfurizer, 25 ... Water purifier, 26 ... Water tank, 27 ... Evaporator, 28 ... Mixer, 30 ... Reformer, 32 ... Combustion part, 34 DESCRIPTION OF SYMBOLS ... CO selective oxidation part, 40 ... Fuel cell, 41 ... Blower, 42 ... Anode offgas heat exchanger, 43 ... Cooling water circulation path, 44 ... Cathode offgas heat exchanger, 45 ... Combustion exhaust gas heat exchanger, 46 ... Cooling water heat Exchanger 47 ... reservoir tank 48 ... circulation pump 49 ... inverter 50 ... heat exchange medium circulation path 51 ... circulation pump 52 ... hot water tank 54 ... heat exchange medium 410 ... single cell 412 ... electrolyte membrane 414 ... anode, 415 ... fuel gas supply path, 416 ... cathode, 417 ... oxidizing gas supply path, 418, 420 ... separator.

Claims (13)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas supplied to the anode and an oxidizing gas supplied to the cathode;
An anode offgas heat exchanging section for recovering heat of the anode offgas discharged from the anode by a heat exchange medium;
A cathode offgas heat exchanging section for recovering heat of the cathode offgas discharged from the cathode by the heat exchange medium;
A heat exchange medium reservoir for storing the heat exchange medium;
A heat exchange medium that circulates the heat exchange medium in a circulation path that returns to the heat exchange medium storage section through the anode offgas heat exchange section and the cathode offgas heat exchange section arranged in a random order in series from the heat exchange medium storage section A fuel cell power generation system comprising a circulation unit. The fuel cell power generation system according to claim 1,
A fuel gas generator that supplies a hydrogen-rich gas obtained by a reaction between a hydrocarbon-based fuel and water to the anode as the fuel gas;
A combustion section that heats the fuel gas generation section by burning a combustion gas,
The anode off-gas heat exchange unit also has a condenser function, and supplies the anode off-gas after collecting heat and condensed water by the heat exchange medium to the combustion unit as the combustion gas. The fuel cell power generation system according to claim 2, wherein in the circulation path, the anode offgas heat exchange unit is arranged upstream of the cathode offgas heat exchange unit. The fuel cell power generation system according to claim 3, wherein the circulation path has the anode off-gas heat exchanging unit disposed in the uppermost stream. The fuel cell power generation system according to any one of claims 1 to 4,
Moisture in the cathode off-gas in the cathode off-gas heat exchanging unit that also functions as a condenser in a fuel gas generating unit that supplies a hydrogen-rich gas obtained by a reaction between a hydrocarbon-based fuel and water as the fuel gas to the anode. A fuel cell power generation system comprising a condensed water supply unit that supplies high-purity water obtained by condensing water to react with the hydrocarbon fuel. The condensed water supply unit supplies the high purity water obtained by condensing moisture in the anode off gas in the anode off gas heat exchange unit to the fuel gas generation unit in order to react with the hydrocarbon fuel. 5. The fuel cell power generation system according to 5. The fuel cell power generation system according to claim 5 or 6,
It has a water purification unit that purifies tap water,
The water purification unit replenishes the condensed water supply unit with a shortage of the high-purity water supplied to the fuel gas generation unit. The fuel cell power generation system according to any one of claims 1 to 4,
A condensed water purifying unit for purifying water obtained by condensing moisture in the cathode offgas in the cathode offgas heat exchanging unit also having a function of a condenser;
A refined water purified by the condensed water purifying unit and a hydrocarbon-based fuel are supplied to a fuel gas generating unit that supplies a hydrogen-rich gas obtained by a reaction between a hydrocarbon-based fuel and water as the fuel gas to the anode. A fuel cell power generation system comprising a purified water supply unit to be supplied for reaction. The fuel cell power generation system according to claim 8,
The said condensed water refinement | purification part refine | purifies also the water obtained by condensing the water | moisture content in anode offgas in the said anode offgas heat exchange part. The fuel cell power generation system according to claim 1, wherein the heat exchange medium is water or hot water, and the heat exchange medium storage unit is a hot water storage tank. The circulation path is a fuel gas that supplies a hydrogen-rich gas obtained by a reaction between a hydrocarbon-based fuel and water to the anode as a fuel gas downstream of the anode offgas heat exchange unit and the cathode offgas heat exchange unit. The combustion exhaust gas heat exchange part which collect | recovers with the said heat exchange medium the heat | fever of the combustion exhaust gas discharged | emitted from the combustion part heated by burning the gas for combustion in a production | generation part is arrange | positioned. The fuel cell power generation system described. In the circulation path, a cooling medium heat exchanging unit that recovers heat of the cooling medium that cools the fuel cell by the heat exchanging medium is disposed downstream of the anode off gas heat exchanging unit and the cathode off gas heat exchanging unit. The fuel cell power generation system according to claim 1. The fuel cell power generation system according to claim 12, wherein the cooling medium heat exchanging unit is disposed on the most downstream side of the circulation path.

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