JP2008198400A - Fuel cell power generation system - Google Patents

Abstract

[PROBLEMS] To reduce the cost by simplifying the system configuration, improve the economic efficiency by reducing the load on the ion exchange resin, reducing the frequency of continuous use and refilling for a long time, and further improving the sulfur in the reformed water. Provided is a fuel cell power generation system that exhibits excellent reliability by preventing compound outflow.
A combined heat exchanger, a condensed water tank, a battery cooling water tank, and a pure water tank are integrally formed in the composite heat exchanger. In these tanks 14, 30 and 31, surplus water overflowing from the pure water tank 31 is led to the battery cooling water tank 30, and surplus water overflowing from the battery cooling water tank 30 is led to the condensate water tank 14, and the condensate water tank 14 The water level is adjusted so that excess water overflowing from the fuel cell is discharged outside the fuel cell power generation system. The water in the pure water tank 31 is supplied to the fuel reforming system 2 as the reformed water 3, and the battery cooling water 18 in the battery cooling water tank 30 is circulated and supplied to the fuel cell main body 5.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell power generation system that improves the performance of a water treatment system in order to treat battery cooling water and the like.

  In general, a fuel cell power generation system takes out electricity directly by electrochemically reacting hydrogen as a fuel and oxygen as an oxidant, and can take out electrical energy with high efficiency. In addition, the system is excellent in environmental performance with low noise and no harmful exhaust gas. Therefore, it has attracted a great deal of attention, and recently, recently, a small fuel cell power generation system using a solid polymer electrolyte membrane as an electrolyte has been developed and used for small businesses and households.

  A fuel cell power generation system for home use is a combined heat and power supply that supplies electric power and exhaust heat accompanying power generation, and is used as a so-called cogeneration system. Currently, technology development is centered on fuel cell power generation systems that generate electricity from hydrogen-derived raw fuels such as city gas, LP gas, and kerosene, which already have a fuel supply base, by reforming reaction with steam. With the expansion of needs, not only improvement of power generation efficiency and quality but also further cost reduction is desired.

  By the way, in the fuel cell power generation system, battery cooling water flows to maintain the fuel cell that has generated heat due to the chemical reaction at a predetermined operating temperature. In addition, a stable supply of reforming water is indispensable for a fuel reforming system for steam reforming a hydrocarbon-based raw fuel. Furthermore, since the fuel cell power generation system, which is a cogeneration system, collects hot exhaust gas and cools it to acquire thermal energy, condensed water is generated as the exhaust gas is cooled. That is, the fuel cell power generation system requires a water treatment system for treating the battery cooling water, reformed water or condensed water, and the water treatment system is an important component that affects the performance as a cogeneration system. ing.

  For example, among the water treatment systems, in the battery cooling water system for treating the battery cooling water, the cooling water is supplied to the fuel cell by the circulation pump, and the battery cooling water that has passed through the fuel cell is cooled by the heat exchanger and then returned to the tank. It is a circulatory system. When the conductivity of the circulated battery cooling water increases, there is a risk of short-circuiting within the fuel cell, resulting in a decrease in the amount of power generation and a further stoppage of power generation. For this reason, in a battery cooling water system, the process which always makes the electrical conductivity of battery cooling water low is calculated | required.

  Here, a conventional example of a fuel cell power generation system including a water treatment system will be specifically described with reference to FIG. As shown in FIG. 3, the fuel cell package 1 includes a fuel reforming system 2 having a reformer burner 12, a fuel cell body 5 having an anode 5a and a cathode 5b, a decarboxylation tower 19, a heat exchanger 16, and a condensation. A composite heat exchanger 13 incorporating a water tank 14 is installed. Hereinafter, each component will be described along the flow of various gases and water flowing in the fuel cell package 1.

  First, hydrocarbon-based raw fuel F is supplied to the fuel cell package 1 from a storage facility such as a pipeline or a gas cylinder. The raw fuel F supplied to the fuel cell package 1 is sent to the fuel reforming system 2. The fuel reforming system 2 includes a desulfurizer that desulfurizes the raw fuel F, a steam reformer, a CO converter, and a CO selective oxidizer.

  In the fuel reforming system 2, the raw fuel F is desulfurized in a desulfurizer, and then mixed with the vaporized reformed water 3, steam reforming reaction in a steam reformer, carbon monoxide in a CO converter ( Hydrogen rich reforming including methane, CO, carbon dioxide (CO2), etc., whose CO concentration has been reduced below the limit value in the fuel cell main body 5 through a CO) shift reaction and a CO selective oxidation reaction in a CO selective oxidizer Gas 4 is produced.

  The reformed gas 4 generated in the fuel reforming system 2 is introduced into the anode 5 a of the fuel cell main body 5. Oxygen in the atmosphere is supplied to the cathode 5 b of the fuel cell body 5 through the air filter 38 by the air blower 6. In the fuel cell main body 5, hydrogen in the anode 5 a and oxygen in the cathode 5 b are reacted and consumed, and power generation is performed. The fuel cell main body 5 is circulated with battery cooling water 18 for maintaining the fuel cell main body 5 at an optimum operating temperature.

  In the fuel cell body 5, after the reaction between hydrogen and oxygen, the anode exhaust gas 7 is discharged from the anode 5a, and the cathode exhaust gas 17 is discharged from the cathode 5b. Among these, the anode exhaust gas 7 is sent to the heat exchanger 8. Waste heat recovery circulating water 10 is introduced into the heat exchanger 8 from a hot water tank 9 installed outside the fuel cell package 1, and the anode exhaust gas 7 is cooled by heat exchange with the exhaust heat recovery circulating water 10, so that the anode Exhaust gas condensed water 11 is generated. The anode exhaust gas condensed water 11 is sent to the condensed water tank 14 of the composite heat exchanger 13.

  The anode exhaust gas 7 from which the anode exhaust gas condensed water 11 has been removed by cooling in the heat exchanger 8 is introduced into the fuel inlet of the reformer burner 12 of the fuel reforming system 2. It is burned with supplied air (not shown) and used as a heat source for the steam reforming reaction in the steam reformer. At this time, since the combustion exhaust gas 15 is generated in the reformer burner 12, the combustion exhaust gas 15 is sent to the composite heat exchanger 13.

  On the other hand, the cathode exhaust gas 17 discharged from the cathode 5b of the fuel cell main body 5 consumes oxygen with power generation, and the oxygen concentration is reduced from the atmosphere. Such cathode exhaust gas 17 is guided to a decarbonation tower 19 in the composite heat exchanger 13. Moreover, the battery outlet water of the battery cooling water 18 is also introduced into the decarbonation tower 19 together with the cathode exhaust gas 17, and the carbon dioxide gas in the battery cooling water 18 is reduced here. The battery cooling water 18 with reduced carbon dioxide gas is sent to the condensed water tank 14 of the composite heat exchanger 13.

  The combustion exhaust gas 15 from the reformer burner 12 and the cathode exhaust gas 17 that has passed through the decarbonation tower 19 are sent to the composite heat exchanger 13, and the heat exchanger 16 (exhaust heat from the hot water storage tank 9) inside the composite heat exchanger 13. The recovered circulating water 10 is cooled via a heat exchanger 8), and combustion exhaust gas condensed water 39 and cathode exhaust gas condensed water 40 are generated. Condensed water 39 and 40 from the exhaust gases 15 and 17 accumulate in the condensed water tank 14 together with the anode exhaust gas condensed water 11 and the battery cooling water 18 described above. The exhaust gases 15 and 17 after the condensed water 39 and 40 are removed are discharged from the composite heat exchanger 13 to the atmosphere.

  The condensed water 11, 39, 40 and the battery cooling water 18 collected in the condensed water tank 14 are supplied again to the fuel cell main body 5 as the battery cooling water 18 by the battery cooling water pump 21, and at the same time, the reforming water pump 25. Thus, the reformed water 3 is supplied to the fuel reforming system 2. According to the power generation system provided with such a water treatment system, it is possible to reduce or eliminate make-up water from outside the system system, which can contribute to the improvement of system efficiency.

  By the way, as described above, in the battery cooling water system which is a circulation system, the conductivity of the battery cooling water must always be lowered. As a factor for increasing the conductivity in the water flowing through the water treatment system, in the case of a fuel cell power generation system using a hydrogen-rich gas obtained by steam reforming a hydrocarbon-based fuel, the example shown in FIG. In other words, in the case of a power generation system having the fuel reforming system 2, the following can be considered. That is, in the anode 5a that is the fuel electrode of the fuel cell main body 5, a gas containing a large amount of carbon dioxide of several tens% comes into contact with the battery cooling water 18, and at this time, the carbon dioxide gas dissolves into the battery cooling water 18.

  Further, since the anode exhaust gas 7 from the anode 5a of the fuel cell 5 and the combustion exhaust gas 15 of the reformer burner 12 contain carbon dioxide, the condensed water 11 and 39 obtained by cooling this also contain carbon dioxide. It will be. Furthermore, ammonia produced by the reformer of the fuel reforming system 2, metal ions from pipes and containers used in the entire system system, and the like are eluted into the water. These carbon dioxide, ammonia, and metal ions are all factors that increase the conductivity in water.

  Therefore, in the water treatment device of the fuel cell system described in Patent Document 1, a conductivity reducing device filled with an ion exchange resin or the like is installed and generated from exhaust gas from the fuel cell or combustion exhaust gas from the reformer. Conductivity reduction processing is carried out for the condensed water. However, if a large amount of carbon dioxide gas flows into the battery cooling water system, the conductivity reduction treatment by the ion exchange resin is not in time, the conductivity of the battery cooling water increases, and a short circuit occurs in the fuel cell, resulting in a decrease in the amount of power generation. There was a risk of power generation stopping.

  Therefore, in the technique described in Patent Literature 2, the battery cooling water system conductivity is reduced by the following configuration. That is, as shown in FIG. 3, the anode exhaust gas condensate 11, the combustion exhaust gas condensate 39 from the reformer burner 12, the cathode exhaust gas condensate 40, and the battery cooling water 18 are collectively collected in the condensate water of the composite heat exchanger 13. After accumulating in the tank 14, the battery cooling water 18 is divided into two directions to be 18a and 18b.

  An ion exchange resin for removing a cation and an anion in the water after installing a heat exchanger 22 for lowering the temperature of the outlet of the fuel cell in one of the branched water systems 18a and cooling it downstream thereof. An ion exchange resin tower 24 filled with 23 is provided. For the reformed water 3, an activated carbon tower 26 and an ion exchange resin tower 27 are installed for removing substances that become poisoning components of the reforming catalyst contained in the reformed water system.

In the technique described in Patent Document 2 having such a configuration, the ion-exchange resin tower 24 is installed in the battery cooling water system, and the activated carbon tower 26 and the ion-exchange resin tower 27 are installed in the reformed water system. Water purification is performed separately. For this reason, the electrical conductivity of the battery cooling water 18 can be maintained at a low level, and the load of the ion exchange resin 23 can be suppressed by diverting the battery cooling water 18.
JP 2005-129334 A Japanese Patent Application No. 2006-8036

  However, the fuel cell power generation system of Patent Document 2 described above has the following problems. First, as a first problem, the ion-exchange resin tower 24 is installed in the battery cooling water system, and the activated carbon tower 26 and the ion-exchange resin tower 27 are installed in the reforming water system. As a result, high costs were incurred.

  As a second problem, since the battery cooling water 18 is divided in two directions, the battery cooling water 18 passes through the ion exchange resin tower 24 only at a certain rate. Therefore, if the condensed water accumulated in the condensed water tank 14 contains many unexpected impurities, it takes a long time to purify the water quality of the battery cooling water 18, resulting in a decrease in battery performance. It was.

  Thus, in the prior art, the load on the ion exchange resin is large, continuous use for a long time is difficult, and the ion exchange resin must be refilled frequently, which is economically disadvantageous. In order to solve this problem, a method of purifying only condensed water with an ion exchange resin as in the system of Patent Document 1 is also conceivable, but in this case, the amount of water to be purified is only condensed water. It becomes difficult to purify.

  As a third problem, an ion exchange resin used for water purification may be decomposed by an oxidizing agent such as dissolved oxygen in water to elute an organic sulfur compound. Since the organic sulfur compound is a poisoning component of the reforming catalyst, the reforming catalyst is deteriorated. That is, the ion exchange resin for removing the conductivity reducing factor substance has deteriorated the performance of the fuel reforming system. For this reason, when using an ion exchange resin, it was desired to prevent the organic sulfur compound from flowing out.

  The present invention has been proposed in order to solve the above-mentioned problems. The system configuration is simplified to reduce the cost, the load on the ion exchange resin is reduced, the continuous use for a long time and the refill frequency are reduced. Thus, it is an object of the present invention to provide a fuel cell power generation system that improves economy and further prevents the outflow of sulfur compounds to reformed water and exhibits excellent reliability.

  In order to achieve the above object, the present invention is provided with a fuel reforming system for producing a hydrogen rich gas by a steam reforming reaction using a hydrocarbon fuel as a raw fuel, and the hydrogen produced by the fuel reforming system. In a fuel cell power generation system provided with a fuel cell main body in which rich gas is taken into the anode as a fuel, oxygen in the air is taken into the cathode as an oxidant to generate electric power, and battery cooling water is circulated to maintain a predetermined operating temperature A condensed water generating means for generating condensed water by cooling the fuel reforming gas or the exhaust gas discharged from the fuel cell main body, and a condensed water tank for storing the condensed water generated by the condensed water generating means, Purified by a water purification device that purifies the quality of the condensed water stored in the condensed water tank, a battery cooling water tank that stores the battery cooling water, and the water purification device. A deionized water tank for storing water is disposed, and the condensate water tank, the battery cooling water tank, and the pure water tank are configured such that excess water overflowing from the deionized water tank is led to the battery cooling water tank, and the battery cooling water tank The surplus water overflowing from the condensate water tank is guided to the condensate water tank, the water level of each tank is adjusted so that the surplus water overflowing from the condensate water tank is discharged out of the fuel cell power generation system, and the water in the pure water tank Is piped so as to be supplied to the fuel reforming system as reforming water, and is piped so as to supply the battery cooling water in the battery cooling water tank to the fuel cell main body. is there.

  In the present invention having the above-described configuration, the condensed water obtained from the fuel reforming system or the fuel cell main body is stored in the condensed water tank, and the water subjected to the water purification from the condensed water tank via the water purification device. The pure water tank is fed to the fuel reforming system as reformed water. That is, the water purification device is installed only in the reforming water system, and it is not necessary to install the water purification device in the battery cooling water system. For this reason, compared with the case where the water purification apparatus is attached to both the reforming water system and the battery cooling water system, the system configuration can be simplified and the cost can be reduced.

  Further, the battery cooling water is stored in a dedicated tank without being mixed with the generated condensed water, and is supplied to the fuel cell main body only from this tank. At that time, water supply to the battery cooling water tank is performed by taking in surplus water from a pure water tank with high water quality. Therefore, it is easy to maintain the water quality of the water stored in the battery cooling water tank high, and it is possible to contribute to reducing the conductivity of the battery cooling water. In addition, surplus water overflowing from the condensate tank is discharged outside the fuel cell power generation system, so that a large amount of condensate is not sent to the water purification device, and the load on the water purification device can be reduced. .

  According to the fuel cell power generation system of the present invention, the condensed water stored in the condensed water tank is purified by the water purification device and sent to the pure water tank, and only the water in the pure water tank is used as the reforming water. The battery cooling water in the battery cooling water tank is supplied to the fuel cell main body, and the excess water of the pure water tank is allowed to flow to the battery cooling water tank, thereby simplifying the system configuration and The water quality of cooling water and reforming water can be improved efficiently, and excellent reliability and economy can be exhibited.

(Representative embodiment)
[Constitution]
Hereinafter, a representative embodiment of a fuel cell power generation system according to the present invention will be described with reference to FIG. FIG. 1 shows a configuration diagram of this embodiment. In addition, the same code | symbol is attached | subjected regarding the member same as the prior art shown in FIG.

  The fuel cell package 1 shown in FIG. 1 includes a fuel reforming system 2, a fuel cell main body 5, a composite heat exchanger 13, a water purification device 33, and a decarboxylation tower 19 as main components. Since the basic configuration of such a fuel cell package 1 is the same as that of the prior art of FIG. 3, the description of the overlapping parts will be omitted, and only the differences will be described.

  The difference from the prior art of FIG. 3 is that in the fuel reforming system 2 of this embodiment, the process gas before being introduced into the CO selective oxidizer is cooled to obtain the reformed gas condensed water 32. Yes. The reformed gas condensed water 32 is introduced into the condensed water tank 14 of the composite heat exchanger 13. That is, the condensed water collected in the condensed water tank 14 is the reformed gas condensed water 32, the anode exhaust gas condensed water 11, the combustion exhaust gas condensed water 39, and the cathode exhaust gas condensed water 40. Reference numeral 41 denotes condensed water that is stored in the condensed water tank 14 and flows out of the tank 14.

  The composite heat exchanger 13 is a characteristic component of the present embodiment, and a battery cooling water tank 30 and a pure water tank 31 are integrally formed adjacent to a condensate water tank 14 provided in the lower part. Yes. In addition, a fixed amount of pure water from which impurities have been removed in advance and whose conductivity has been reduced is supplied to the storage tanks of the tanks 14, 30, and 31 before the power generation operation of the fuel cell power generation system.

  The water levels of the condensed water tank 14, the battery cooling water tank 30 and the pure water tank 31 are such that excess water overflowing from the pure water tank 31 is led to the battery cooling water tank 30, and excess water overflowing from the battery cooling water tank 30 is condensed water tank. 14 is adjusted so that surplus water overflowing from the condensed water tank 14 is discharged out of the fuel cell power generation system.

  The water stored in the pure water tank 31 is pure water 42 whose water quality has been purified by the water quality purification device 33 and is piped so as to be supplied to the fuel reforming system 2 as the reformed water 3 via the pump 25. ing. The water stored in the battery cooling water tank 30 is circulating water for maintaining the fuel cell main body 5 at an optimum operating temperature, and is circulated and supplied to the fuel cell main body 5 as the battery cooling water 18. The battery cooling water 18 returns from the fuel cell main body 5 to the battery cooling water tank 30 via the decarbonation tower 19 and the heat exchanger 22.

  Further, as in the conventional example of FIG. 3, the combustion exhaust gas 15 and the cathode exhaust gas 17 are introduced into the composite heat exchanger 13, and these exhaust gases 15 and 17 are cooled by the heat exchanger 16. A partition plate 37 that is inclined downward is attached below the heat exchanger 16. The edge of the partition plate 37 is disposed above the condensed water tank 14.

  Further, a water purification device 33 is connected to the condensed water tank 14 via a pump 35 and a heat exchanger 36. The water purification device 33 is a device that receives the condensed water 41 flowing out from the condensed water tank 14 and purifies the water quality of the condensed water 41 to generate pure water 42, and sends the pure water 42 to the pure water tank 31. It is configured as follows.

  More specifically, the upstream side (lower side in FIG. 1) of the water purification device 33 is filled with a cation exchange resin 23a having a crosslinking degree of 10% or more, and the downstream side (upper side in FIG. 1) is negative. The ion-exchange resin 23b is filled and arranged so as to allow water to flow therethrough. Note that the amount of pure water supplied from the water purification device 33 to the pure water tank 31 is the amount of reformed water supplied from the pure water tank 31 to the fuel reforming system 2 as the reformed water 3 (that is, the amount of pure water discharged). Is set more than. In addition, a heat exchanger 36 for cooling the condensed water 41 sent from the condensed water tank 14 to the water quality purification device 33 is provided between the condensed water tank 14 and the water quality purification device 33.

  By the way, a drain pipe 34 is inserted and connected to the condensed water tank 14 from the bottom surface of the tank, and excess water from the condensed water tank 14 is discharged from the fuel cell power generation system through the drain pipe 34. . Further, a pipe 47 through which the reformed gas condensed water 32 is sent from the fuel reforming system 2 is connected to the drain pipe 34, and when the water in the condensed water tank 14 is excessive during the power generation operation of the fuel cell power generation system. The reformed gas condensate 32 is guided to the outside of the system through the drain pipe 34, and the reformed gas condenses to the condensate tank 14 through the pipe 47 only when the water in the condensate tank 14 is insufficient. Water 32 is introduced.

  Unlike the structure of the conventional example shown in FIG. 3, the decarbonation tower 19 is installed not independently of the composite heat exchanger 13 but independently of the composite heat exchanger 13. There is no change in the point where the battery outlet water of water 18 is introduced. The decarbonation tower 19 is filled with a porous structure called terrarette made of a heat-resistant resin such as polypropylene or a metal such as a carbon steel stainless steel, or a multi-stage flat plate to widen the contact area between water and gas. Or is installed.

[Gas and water flow]
The flow of various gases and water in the fuel cell package 1 is as follows. First, the raw fuel F is sent to the fuel reforming system 2 of the fuel cell package 1 to generate the reformed gas 4, which is introduced into the fuel cell body 5 anode 5a to become fuel, which is consumed by power generation together with oxygen on the cathode 5b side. Is done.

  The anode exhaust gas 7 not consumed by the anode 5a of the fuel cell body 5 is cooled by heat exchange with the exhaust heat recovery circulating water 10 in the heat exchanger 8, and after the anode exhaust gas condensed water 11 is removed, the fuel reforming system The fuel is introduced into the fuel inlet of the reformer burner 12 and burned, and the combustion exhaust gas 15 is sent to the composite heat exchanger 13. Further, the anode exhaust gas condensed water 11 generated in the heat exchanger 8 is sent to the condensed water tank 14 of the composite heat exchanger 13.

  On the other hand, the low oxygen concentration cathode exhaust gas 17 discharged from the fuel cell main body 5 cathode 5 b is guided to the composite heat exchanger 13 via the decarboxylation tower 19. The exhaust gases 15 and 17 introduced into the composite heat exchanger 13 are cooled by the heat exchanger 16 and the condensed water 39 and 40 are removed. Condensed water 39 and 40 of the exhaust gases 15 and 17 are cooled and condensed by the heat exchanger 16, fall on the partition plate 37 below the heat exchanger 16, and are transmitted through the condensed water in the composite heat exchanger 13. It flows into the tank 14. The exhaust gases 15 and 17 after the condensed water 39 and 40 are removed are discharged from the composite heat exchanger 13 to the atmosphere.

  As described above, the condensed water tank 14 includes the reformed gas condensed water 32 obtained by cooling the process gas before being introduced into the CO selective oxidizer, and the anode exhaust gas condensation obtained by cooling the battery anode exhaust gas 7. Water 11, combustion exhaust gas condensed water 39 obtained by cooling the combustion exhaust gas 15 from the reformer burner 12, and cathode exhaust gas condensed water 40 obtained by cooling the battery cathode exhaust gas 17 are stored. The condensed water 11, 32, 39, 40 stored in the condensed water tank 14 is sent to the heat exchanger 36 via the pump 35, where the temperature is reduced and then supplied to the water purification device 33. The As a cooling heat source for the heat exchanger 36, exhaust heat recovery circulating water 10 that has exited the heat exchanger 8, air before being introduced into the cathode 5b, or the like is used.

  Condensed water 41 from the condensed water tank 14 supplied to the water purification device 33 passes through the anion exchange resin 23b and the cation exchange resin 23a to remove cations and anions to become pure water 42. The water tank 31 is supplied. The pure water 42 accumulated in the pure water tank 31 is supplied to the fuel reforming system 2 as the reformed water 3 through the pump 25. In addition, when a predetermined amount or more of pure water 42 has accumulated in the pure water tank 31, the excess overflows from the tank 31 and flows into the adjacent battery cooling water tank 30.

  Circulating water in the battery cooling water tank 30 is circulated and introduced into the fuel cell main body 5 as battery cooling water 18. The battery cooling water 18 exiting the fuel cell main body 5 is introduced into the decarbonation tower 19 together with the cathode exhaust gas 17 to reduce carbon dioxide in the water, and after the temperature is reduced by the heat exchanger 22, the battery cooling water tank is again formed. Return to 30. The circulating water in the battery cooling water tank 30 is supplemented with water lost in the fuel cell main body 5 and the decarbonation tower 19 by pure water 42 overflowing from the pure water tank 31. In addition, surplus water in the battery cooling water tank 30 passes over the wall surface of the tank 30 and overflows to the condensed water tank 14.

  During the power generation operation of the fuel cell power generation system, if the condensed water in the condensed water tank 14 is excessive, it flows out of the system system through the drain pipe 34. In addition, when the water in the condensed water tank 14 is insufficient, the reformed gas condensed water 32 is introduced from the fuel reforming system 2 via the pipe 47 and the drain pipe 34. However, the reformed gas condensate 32 is not introduced into the tank 14 unless the condensate stored in the condensate tank 14 is insufficient, and is discharged from the drain pipe 34 before the tank 14 to the outside of the system system. Is discharged.

  The heat utilized in the present embodiment is the heat from the heat exchanger 8, the heat exchanger 16, and the heat exchanger 22 of the exhaust heat recovery circulating water 10 introduced from the hot water tank 9 into the fuel cell package 1. Obtained by recovery. Further, in the above embodiment, the heat supply system using water to the hot water tank 9 which has many application examples is taken up. However, the supply form of heat to the use destination is not limited to the hot water tank 9, and the waste water is discharged. The medium flowing through the heat recovery circulation system is not limited to water.

[Function and effect]
The operational effects of the present embodiment as described above are as follows. That is, in the present embodiment, pure water 42 subjected to water purification from the condensed water tank 14 via the water purification device 33 is sent to the pure water tank 31, and only the pure water 42 is used as the reforming water 3. . In this embodiment, the water purification device 33 is included only in the reforming water system, and the water purification device is not installed in the battery cooling water system. Therefore, compared with the case where the water purification apparatus is attached to both water systems, the system configuration can be simplified and the manufacturing cost can be greatly reduced.

  The battery cooling water tank 30 storing the battery cooling water 18 is supplied with pure water 42 from the high-quality pure water tank 31 side, but is condensed from the condensed water tank 14 with low water quality. Water 41 does not flow. Moreover, in this embodiment, the amount of water supplied from the water purification device 33 to the pure water tank 31 is greater than the amount of water supplied as the reformed water 3 from the pure water tank 31 (pure water discharge amount). Since it is set, the excess water amount of the pure water 42 overflowing from the pure water tank 31 is large.

  For this reason, the pure water 42 can sufficiently overflow from the pure water tank 31 to the battery cooling water tank 30. Furthermore, excessive battery cooling water 18 overflows from the battery cooling water tank 30 to the condensed water tank 14. Therefore, the battery cooling water 18 can be purified efficiently. Thereby, the water quality of the battery cooling water 18 can be improved, and the conductivity of the battery cooling water 18 can always be kept low.

  Furthermore, since the excess water of the condensed water 41 overflowing from the condensed water tank 14 is discharged out of the fuel cell power generation system, it is possible to suppress the condensed water sent from the condensed water tank 14 to the water purification device 33 to a minimum amount. It is possible to reduce the load on the water purification device 33. In addition, among the condensed water stored in the condensed water tank 14, the reformed gas condensed water 32 contains the largest amount of impurities such as ammonia generated in the fuel reforming system 2. Since the condensed water is introduced into the condensed water tank 14 only when the condensed water is insufficient, the inflow amount of the reformed gas condensed water 32 is actually very small.

  Therefore, the water quality of the condensed water 41 stored in the condensed water tank 14 is higher than that of the reformed gas condensed water 32, and the load of the ion exchange resin 23 filled in the water purification device 33 can be reduced. For this reason, the water purification apparatus 33 can be used continuously for a long time, and it is not necessary to refill ion-exchange resin frequently. As a result, the water purification device 33 can be reduced in size and extended in life, and maintenance is facilitated, which is economically advantageous.

  Further, in the decarbonation tower 19, the high-temperature battery cooling water 18 immediately after exiting the fuel cell body 5 and the cathode exhaust gas 17 having a lower oxygen concentration than air are brought into gas-liquid contact. For this reason, on balance, the carbon dioxide removal amount in the battery cooling water 18 is greater than that in contact with air, and the amount of dissolved oxygen is also reduced. Thereby, the carbonate ions and dissolved oxygen in the water overflowing from the battery cooling water tank 30 to the condensed water tank 14 are reduced, and the load of the ion exchange resins 23a and 23b filled in the water purification device 33 can be reduced. At the same time, decomposition of the ion exchange resins 23a and 23b due to oxidation is suppressed.

  Moreover, by filling the cation exchange resin 23a having a high degree of crosslinking upstream of the water purification device 33 and the anion exchange resin 23b downstream, the sulfur compound which is a functional group of the cation exchange resin 23a is oxidized and decomposed. Even if it flows out, it can be removed by the downstream anion exchange resin 23b, and the pure water 42 as the reformed water 3 does not contain sulfur. Therefore, even if the reforming water 3 is supplied to the fuel reforming system 2, the reforming catalyst arranged in the fuel reforming system 2 is not poisoned.

  In addition, since the water quality purification device 33 passes through the water in an upward flow, the cation exchange resin 23a having a high specific gravity is not mixed with the anion exchange resin 23b downstream. With the above effects, the electric conductivity of the battery cooling water 18 can be kept low for a long period of time, and there is no fear that the sulfur compound that becomes a poisoning component of the reforming catalyst flows out to the reforming water 3. Thereby, a highly reliable fuel cell power generation system can be provided.

(Other embodiments)
In addition, this invention is not limited to said embodiment, The structure and arrangement | positioning of each member can be changed suitably. For example, the water storage tank 45 shown in FIG. 2 has a condensate water tank 14, a battery cooling water tank 30, and a pure water tank 31 formed integrally with the lower part of the composite heat exchanger 13 of FIG. 1. The arrangement configuration of the excess water inflow / outflow portion in the battery cooling water tank 30 is limited.

  That is, in the battery cooling water tank 30, the circulating water discharge portion 44 that drains surplus water to the condensed water tank 14 is disposed in the vicinity of the inlet 46 where the battery cooling water 18 returns, and surplus from the pure water tank 31. The pure water introduction part 43 for taking in pure water is arranged on a diagonal line farthest from the circulating water discharge part 44. The upper surface of the water storage tank 45 may be sealed, or a latent heat recovery heat exchanger for the reformer combustion exhaust gas and the fuel cell cathode exhaust gas is integrally disposed at the upper portion, and dew condensation occurs in the heat exchanger. The condensed water may be directly stored in the condensed water tank (not shown).

  In such an embodiment, the inlet 46 for returning the battery cooling water 18 to the battery cooling water tank 30 is separated from the pure water introduction part 43 and close to the circulating water discharge part 44. For this reason, of the circulating water stored in the battery cooling water tank 30, high-quality water close to the pure water introduction portion 43 can stay in the battery cooling water tank 30 for a long time. The relatively low-quality water that has just returned to the inside 30 can easily flow into the condensed water tank 14. Thereby, the water quality of the battery cooling water 18 stored in the tank 30 can be kept at a high level without installing the water purification device independently on the battery cooling water system side. Therefore, the conductivity of the battery cooling water can be kept low without increasing the cost burden by increasing the number of water purification devices, and excellent economic efficiency and reliability can be obtained.

The block diagram of typical embodiment of this invention. The perspective view of the water storage tank in other embodiments of the present invention. The block diagram of the conventional fuel cell power generation system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell package 2 ... Fuel reforming system 3 ... Reformed water 4 ... Reformed gas 5 ... Fuel cell main body 5a ... Anode 5b ... Cathode 6 ... Air blower 7 ... Anode exhaust gas 8, 16, 22, 36 ... Heat exchange Apparatus 9 ... Hot water storage tank 10 ... Waste heat recovery circulating water 11 ... Anode exhaust gas condensed water 12 ... Reformer burner 13 ... Combined heat exchanger 14 ... Condensed water tank 15 ... Combustion exhaust gas 17 ... Anode exhaust gas 18 ... Battery cooling water 19 ... Decarbonation tower 21 ... Battery cooling water pump 23 ... Ion exchange resin 23a ... Cation exchange resin 23b ... Anion exchange resin 24 ... Ion exchange resin tower 25 ... Reformed water pump 26 ... Activated carbon tower 27 ... Ion exchange resin tower 30 ... Battery cooling water tank 31 ... pure water tank 32 ... reformed gas condensed water 33 ... water purification device 34 ... drainage pipe 35 ... pump 37 ... partition plate 38 ... air filter 39 ... combustion exhaust gas condensed water 40 Cathode exhaust condensed water 41 ... condensed water condensed water flows out from the tank 42 ... pure 43 ... pure water inlet portion 44 ... feed water discharge portion 45 ... holding tank 46 ... inlet 47 ... pipe

Claims (9)

A fuel reforming system for producing a hydrogen-rich gas by a steam reforming reaction using a hydrocarbon-based fuel as a raw fuel; a hydrogen-rich gas produced by the fuel reforming system as a fuel; and a cathode using oxygen in the air as an oxidant In a fuel cell power generation system provided with a fuel cell main body that circulates battery cooling water for generating power and maintaining a predetermined operating temperature,
Condensed water generating means for cooling the exhaust gas discharged from the fuel reforming system gas or the fuel cell main body to generate condensed water;
A condensed water tank for storing the condensed water generated by the condensed water generating means;
A water purification device that purifies the quality of the condensed water stored in the condensed water tank;
A battery cooling water tank for storing the battery cooling water;
A pure water tank for storing water purified by the water purification device is disposed;
The condensed water tank, the battery cooling water tank, and the pure water tank are configured such that surplus water overflowing from the pure water tank is led to the battery cooling water tank, and surplus water overflowing from the battery cooling water tank is led to the condensed water tank. The water level of each tank is adjusted so that excess water overflowing from the condensed water tank is discharged out of the fuel cell power generation system system,
Furthermore, piping is provided so as to supply water in the pure water tank to the fuel reforming system as reformed water,
A fuel cell power generation system, wherein the fuel cell power generation system is piped so as to supply battery cooling water in the battery cooling water tank to the fuel cell main body.   The purified water supply amount that supplies the purified water from the water purification device to the pure water tank is more than the reformed water supply amount that is supplied from the pure water tank to the fuel reforming system as reformed water. The fuel cell power generation system according to claim 1, wherein a large number is set.   As the condensed water generating means, means for cooling the process gas in the fuel reforming system to obtain reformed gas condensed water, means for cooling the combustion exhaust gas combusted in the fuel reforming system, and obtaining combustion exhaust gas condensed water Means for cooling anode exhaust gas discharged from the anode of the fuel cell body to obtain anode exhaust gas condensed water, and means for cooling cathode exhaust gas discharged from the cathode of the fuel cell body to obtain cathode exhaust gas condensed water The fuel cell power generation system according to claim 1 or 2, wherein at least one of them is provided.   The fuel cell power generation system according to any one of claims 1 to 3, wherein the condensed water tank, the pure water tank, and the battery cooling water tank are integrally formed in the same container.   The condensed water generating means is constituted by a heat exchanger that recovers latent heat of the fuel reforming system gas or exhaust gas discharged from the fuel cell main body, and is disposed above the condensed water tank. The fuel cell power generation system according to any one of claims 1 to 4.   The fuel cell power generation system according to any one of claims 1 to 5, further comprising a decarbonation device for removing carbon dioxide in the battery cooling water by gas-liquid contact with the cathode exhaust gas. .   In the water purification device, at least a cation exchange resin having a degree of cross-linking of 10% or more is filled on the upstream side, an anion exchange resin is filled on the downstream side, and arranged to allow water to flow in an upward flow. The fuel cell power generation system according to any one of claims 1 to 6.   The fuel cell power generation system according to any one of claims 1 to 7, further comprising a heat exchanger or a radiator for cooling the condensed water sent from the condensed water tank to the water purification device. . As the condensed water generating means, means for cooling the process gas in the fuel reforming system to obtain reformed gas condensed water is provided,
The reformed gas condensed water generating means and the condensed water tank are introduced into the condensed water tank only when the condensed water stored in the condensed water tank is less than a predetermined amount. The fuel cell power generation system according to any one of claims 1 to 8, wherein the fuel cell power generation system is pipe-connected as described above.

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