JP2006147348A - Fuel cell power generation device and water quality control method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fuel cell power generation device in which bacteria and algae contained in collected water used as cooling water of the battery or the like is appropriately sterilized, capable of stably operating a collected water flow system for a long period. <P>SOLUTION: A switching valve 71, an electric heater 72, a cooling device 73, a water treatment device 74, and a pump 75 are arranged on a flow passage supplying a collected water, obtained by introducing battery cooling water drained out from a battery cooling water flow passage 13 of a fuel cell body 10, air electrode off-gas exhausted from an air electrode 12, and combustion off-gas exhausted from a reforming device burner 21, from a collected water tank 50 to a water storage tank 60. The collected water is heated by the electric heater 72 depending on signals detected by temperature sensors 51, 61 and a water level sensor 62, and the bacteria and algae are sterilized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell power generation device, and more particularly to a fuel cell power generation device that recovers and uses battery cooling water, reaction product water, reformer combustion product water, and the like, and a water quality management method thereof.

The fuel cell power generation device is an environmentally friendly power generation device that has high power generation efficiency and emits almost no air pollutants. In addition, since the fuel cell power generator generates heat during power generation, it is expected that a cogeneration system can be constructed by collecting the heat, and the total energy efficiency reaches 70 to 80%. There are phosphoric acid type and solid polymer type in the fuel cell system, and the phosphoric acid type has been mainly studied as a large scale fuel cell cogeneration system. However, in recent years, the development of the cogeneration system for home use has progressed. Accordingly, application of a polymer electrolyte fuel cell having a low operating temperature of 60 to 90 ° C. and a short start-up time has been studied.
A hydrogen-rich gas used as a fuel gas in a fuel cell is generally obtained by reforming raw fuel such as city gas by reacting with water in a reformer. In order to efficiently generate hydrogen in the reformer, it is necessary to prevent the performance degradation due to poisoning of the reforming catalyst and the reformer performance due to adhesion of impurities such as metal ions. The water supplied to the water must be free from impurities such as catalyst poisons and metal ions. Further, in order to increase the power generation efficiency, it is necessary to keep the fuel cell body at the optimum temperature, heating is necessary to shorten the starting time at the time of startup, and cooling is required at the time of the power generation operation. As the heating medium for heating and cooling, water is usually used, but water with low conductivity must be used to prevent leakage. For this reason, usually, water from which impurities have been removed through a water treatment device is used.

If the power generation operation is continued, a part of the water in the apparatus evaporates and scatters. Therefore, in order to continuously operate the water cooling system, it is necessary to replenish and circulate the water corresponding to the amount of the splatter. As power generation generates reaction water in the fuel cell and combustion generation water in the reformer, the generated water obtained by cooling, condensing and recovering the exhaust gas is used as makeup water. However, since these recoveries vary depending on the operating conditions, when the amount is insufficient, the system is operated by receiving external makeup water. Since the makeup water needs to be replenishable at any time and the replenishment flow rate must be controllable, the above recovered water and external makeup water are once stored in the water storage tank and then introduced into the cooling system. The
However, in the cooling system configured as described above, the recovered water that is condensed and recovered and stored in the water storage tank is almost pure water, and is in a condition where bacteria can easily propagate. Risk of fungus and algae breeding in the recovery water tank due to the invading fungi and the invading fungi from the air exhaust port, and these fungi and algae clogging in the piping and causing malfunction of the cooling system There is. As a method of avoiding this type of malfunction caused by the growth of fungi and algae, as already cited in Patent Document 2, a method using a metal material such as copper or zinc having antibacterial action in the water pathway, A method of using a sterilizer using ultraviolet rays, a method of providing an antibacterial filter in a water path, a method of making water strongly acidic, and the like are disclosed in Patent Document 1 and Patent Document 2, and the temperature of water is heated and sterilized. A method of disinfecting by holding at a temperature higher than the temperature required for the above is disclosed. Among these, in the method disclosed in Patent Document 1, when introducing tap water from the outside, the cooling effect is reduced by reducing the flow rate of cooling water from that during normal operation, and the temperature of the water in the recovered water tank is reduced. It is sterilized by temporarily holding above the temperature required for heat sterilization. Further, in the method disclosed in Patent Document 2, a heating flow path for heating and returning the stored water to a predetermined temperature or higher in a water storage tank that stores water used for at least one of battery cooling water and reforming water, For example, a heating channel that is heated by exhaust heat accompanying power generation of the fuel cell main body or exhaust heat from the reformer is provided, and sterilized water is stored by flowing through this channel and heating temporarily.
JP-A-8-138714 JP 2002-270194 A

As described above, in the fuel cell power generation apparatus, it is necessary to appropriately suppress the growth of fungi and algae that occur in the cooling water system, and various measures have been devised and tried, but each method has advantages and disadvantages. There are still problems to be solved. For example, in the case of the method disclosed in Patent Document 1 described above, in the conventional power generation system using a phosphoric acid fuel cell, the operating temperature of the fuel cell is a few tens of degrees Celsius. Although it is relatively easy to heat above a predetermined temperature required for heat sterilization, the operating temperature is as low as 60 to 90 ° C. in a power generation system using a polymer electrolyte fuel cell that is attracting attention for household use, and exhaust gas Since it is necessary to cool to a lower temperature when recovering heat from water or recovering water, it is difficult to heat the temperature of recovered water above a predetermined temperature required for heat sterilization as in Patent Document 1. It is.
Further, as in the method disclosed in Patent Document 2 above, the water storage tank is provided with a heating flow path for heating and returning the stored water to a predetermined temperature or higher, and this flow path is temporarily heated. In the case of the method of storing sterilized water, there is a problem that the structure becomes complicated, and water that has not been heat sterilized flows through a water treatment device such as a pump or an ion exchange resin, so that clogging of the pump occurs. And the risk of accelerating the deterioration of the characteristics of the water treatment device increases. In addition, since the water in the water storage tank is not differentiated between heated water and unheated water, it is necessary to have sufficient capacity of the heating means such as pumps and heaters. Pump capacity and heating capacity Must be put in excess. Similarly to the case of Patent Document 1, the power generation system using the polymer electrolyte fuel cell has a low operating temperature, and thus there is a possibility that the sterilization cannot be sufficiently performed by heating with the generated heat of the apparatus.

  The present invention has been made in view of the problems of the current state of the art as described above, and an object of the present invention is to recover a reaction product water or a reformer combustion product water and use it as a battery cooling water or the like In the fuel cell power generation device, the recovered water is stored without breeding fungi and algae, and the fuel cell has a recovered water distribution system that can be operated stably for a long time without causing malfunction of the pump or water treatment device In addition to providing a power generation device, it is an object to provide a water quality management method in which recovered water is supplied to a storage tank of a battery cooling water system without causing propagation of fungi and algae.

In the present invention, in order to achieve the above object,
A fuel cell main body, a cooling water circulation passage through which cooling water that cools the fuel cell main body flows, a reformer that generates steam to reform raw fuel and supply fuel gas to the fuel cell main body, A recovery water tank for recovering the generated water by introducing at least one of off-gas containing reaction product water discharged from the fuel cell main body and exhaust gas containing combustion product water discharged from the reformer, and In a fuel cell power generator comprising a water storage tank that stores water sent from a recovered water tank and supplies the stored water to at least one of the cooling water circulation channel and the reformer,
(1) The flow path for sending the recovered water collected in the recovered water tank to the water storage tank through an on-off valve is provided with a heating means for heating the water flowing through the flow path,
(2) Further, in the above (1), the cooling means for cooling the water flowing through the flow path to the downstream side of the heating means of the flow path for sending the recovered water from the recovered water tank to the water storage tank It shall be provided with.

(3) In the above (1) or (2), the water flowing through the flow path is disposed downstream of the heating means of the flow path for sending the recovered water from the recovered water tank to the water storage tank. Drive means for driving from the recovered water tank to the water storage tank is provided.
(4) In the above (1), (2) or (3), a temperature sensor for detecting the temperature of the recovered water in the recovered water tank, and a temperature of the stored water in the water storage tank. A temperature sensor for detecting and a water level sensor for detecting the water level are provided.
(5) In the above (4), when the water level in the water storage tank detected by the water level sensor is below a predetermined water level, the on-off valve is opened and the drive means is operated to collect the water. By passing water, and further, heating and sterilizing the recovered water by operating the heating means when the temperature detected by the temperature sensor in the recovered water tank is equal to or lower than a first predetermined temperature. The water quality of the cooling water for the fuel cell power generator will be managed.

  (6) Alternatively, in (4) above, when the water level in the water storage tank detected by the water level sensor is below a predetermined water level, the on-off valve is opened and the drive means is operated to collect the water. Water is further passed, and the temperature detected by the temperature sensor in the recovered water tank is equal to or lower than a first predetermined temperature, and the temperature detected by the temperature sensor in the water storage tank is When the temperature is equal to or lower than the second predetermined temperature, the quality of the cooling water of the fuel cell power generator is controlled by operating the heating means to heat and sterilize the recovered water.

If heating means for heating the water flowing through the flow path is provided in the flow path for sending the collected water from the recovered water tank to the water storage tank as in (1) above, by operating this heating means, Since the water flowing through the flow path can be primarily heated to be sterilized, the recovered water is surely sterilized. Therefore, even if fungi and algae invade from the outside, their growth is prevented, so that these fungi and algae can control the blockage of the water flow path and deterioration of the characteristics of the water treatment device, and can be operated stably for a long time. It becomes.
Further, as described in (2) above, if a cooling means is provided on the downstream side of the heating means, the recovered water whose temperature has risen by the heating means can be cooled and stored at an appropriate temperature. . Further, as described in (3) above, if the driving means for driving the recovered water to the water storage tank is provided on the downstream side of the heating means, it is possible to prevent the growth of fungi and algae on the upstream side of the driving means. The means can be stably operated without causing problems such as blockage.

  In addition, as described in (4) above, a temperature sensor and a water level sensor are further provided in the recovered water tank and the water storage tank to detect the temperature and water level as described in (5) or (6) above. By operating the on / off valve of the cooling water flow path according to the detection signal and further controlling the operation of the heating means, the heating means is appropriately and surely controlled, the recovered water flowing through the flow path is heated, and fungi and It is possible to suppress the blockage of the water flow path by algae and the deterioration of the characteristics of the water treatment apparatus.

The best mode of the present invention includes a fuel cell main body, a cooling water circulation passage for cooling the fuel cell main body, and reforming for generating fuel gas to be supplied to the fuel cell main body by steam reforming the raw fuel. And at least one of an off-gas containing reaction product water discharged from the fuel cell main body and exhaust gas containing combustion product water discharged from the reformer, and recovering the generated water A fuel cell power generator comprising: a recovered water tank; and a water storage tank that stores the water sent from the recovered water tank and supplies the stored water to at least one of the cooling water circulation channel and the reformer In the embodiment, the flow path for sending the recovered water collected in the recovered water tank to the water storage tank is provided with a heating means for heating the water flowing through the flow path.
In the fuel cell power generator of the above embodiment, a temperature sensor that detects the temperature of the recovered water in the recovered water tank, and a temperature sensor and a water level that detect the temperature of the stored water in the water tank. A water level sensor that detects the water level, and when the water level in the water storage tank detected by the water level sensor is below a predetermined water level, the on-off valve is opened and the drive means is operated to pass the recovered water. Further, when the temperature detected by the temperature sensor in the recovered water tank is equal to or lower than a first predetermined temperature, the heating means is operated to heat and sterilize the recovered water, thereby generating fuel cell power. It is in the water quality management method which manages the quality of the cooling water of the equipment.

  FIG. 1 is a system configuration diagram of an embodiment of a fuel cell power generator according to the present invention. In this figure, reference numeral 10 denotes a fuel cell body provided with a fuel electrode 11, an air electrode 12, and a battery cooling water channel 13, 20 is a reformer, and 21 is a reformer burner. Reference numeral 30 denotes an air humidifier including an air flow path 31 and a humidified water flow path 32, 40 denotes an evaporator, 50 denotes a recovered water tank, 60 denotes a water storage tank, and 71 denotes an open / close valve for discharging the recovered water. The raw fuel made of city gas or the like is taken into the reformer 20 together with the reforming steam supplied from the water storage tank 60 and reformed into a hydrogen-rich reformed gas by a steam reforming reaction. 10 fuel electrodes 11 are sent. On the other hand, the reaction air flows through the air flow path 31 of the air humidifier 30 and is humidified by the humidified water flowing through the humidified water flow path 32 and then sent to the air electrode 12 of the fuel cell main body 10. By sending the reaction air thus humidified, the solid polymer membrane of the fuel cell main body 10 is kept moist and functions as an electrolyte. Further, a part of the fuel electrode off-gas discharged from the fuel electrode 11 after contributing to the electrochemical reaction is sent to the reformer burner 21 through the evaporator and burned to be used for promoting the reforming reaction. The battery cooling water discharged from the battery cooling water flow path 13, the air electrode off-gas discharged from the air electrode 12, a part of the fuel electrode off-gas, and the combustion exhaust gas discharged from the reformer burner 21 are sent to the recovered water tank 50. And is sent to the water storage tank 60 by a pump 75 that is a driving means, and then sent again to the battery cooling water passage 13 of the fuel cell main body 10, the reformer 20, and the humidifying water passage 32 of the air humidifier 30. Used in circulation.

The feature of the embodiment shown in the figure is that an electric heater 72 is provided as a heating means for heating the water circulating between the recovered water tank 50 and the water storage tank 60 of the battery cooling water circulation flow path to a specified temperature or higher. Furthermore, a cooler 73 as cooling means for cooling water circulating downstream of the electric heater 72 is provided so as to be selectable for use, and a pump 75 as driving means for circulating water is provided. And a water treatment device for purifying water is provided on the downstream side of the electric heater 72.
Therefore, in this apparatus, since the recovered water is heat-treated by the heating means provided between the recovered water tank 50 and the water storage tank 60 as described above, fungi and algae are excluded, Clean water is stored and sent again to the battery cooling water flow path 13 of the fuel cell body 10. In addition, since a cooler 73 is selectably provided as a cooling means on the downstream side of the heating means, if this cooler 73 is used, the circulating water after the sterilization treatment is cooled and maintained at an appropriate temperature. be able to. Moreover, since the pump 75 as a drive means and the water treatment apparatus which purifies water are distribute | arranged to the downstream of said heating means, the pump 75 and a water treatment apparatus do not produce the malfunction resulting from fungi and algae. It is possible to drive stably.

  The quality control of recovered water in this apparatus, that is, sterilization of fungi and algae is performed as follows. That is, the on-off valve 71, the electric heater 72, and the pump 75 provided in the flow path for sending the recovered water from the recovered water tank 50 to the water storage tank 60 are all the temperature sensor 51 of the recovered water tank 50 and the water storage tank 60. The operation is controlled by the detection signals of the temperature sensor 61 and the water level sensor 62, and when the water level of the water storage tank 60 detected by the water level sensor 62 is equal to or higher than a predetermined value, the amount of water to be circulated is sufficient. There is no need to replenish from the recovered water tank 50, the on-off valve 71 is kept closed, and the electric heater 72 and the pump 75 are kept stopped. When the amount of water stored in the water storage tank 60 decreases and the water level falls below a predetermined value, the open / close valve 71 is shifted to the open state by the detection signal of the water level sensor, the operation of the pump 75 is started, and the recovered water is transferred to the water storage tank 60. Sent. At this time, if the temperature of the recovered water in the recovered water tank 50 detected by the temperature sensor 51 is higher than a predetermined value, the growth of algae and bacteria is suppressed without reheating. On the other hand, if the temperature of the recovered water is equal to or lower than the predetermined value, the operation of the electric heater 72 is started, the recovered water flowing through the flow path is heated, and algae and bacteria are sterilized. At this time, the cooler 73 is operated in accordance with the operation of the electric heater 72 and plays a role of cooling the recovered water heated for sterilization to a predetermined temperature or lower that can be used as battery cooling water.

When the supply of recovered water from the recovered water tank 50 to the water storage tank 60 and the heating by the electric heater 72 proceed and the amount of recovered water supplied becomes larger than the amount discharged from the water storage tank 60, When the water level rises and the water level detected by the water level sensor 62 exceeds a predetermined value, the operation of the pump 75 is stopped, the on-off valve 71 is shifted to the closed state, and the supply of the recovered water to the water storage tank 60 is stopped. In addition, the operation of the electric heater 72 is stopped, and the operation of the cooler 73 is further stopped.
In the above-described embodiment, the cooler 73 is operated and stopped in accordance with the operation of the electric heater 72. However, the cooler 73 may be operated independently, and the temperature sensor 61 of the water storage tank 60 is used. It is good also as what is drive | operated when the detected temperature of this becomes more than predetermined value, or what is always drive | operated.

  As described above, if the fuel cell power generator is configured as in the present invention, the recovered water is stored without causing fungi and algae to propagate, and stable over a long period of time without causing problems with the pump and water treatment device. A fuel cell power generation device having an operable recovered water distribution system is obtained, and if the water quality management method of the fuel cell power generation device of the present invention is used, the recovered water can be recovered from the battery cooling water system without causing the growth of fungi and algae. These inventions are expected to be widely applied to this type of fuel cell power generator.

The system block diagram of the Example of the fuel cell power generator of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell main body 20 Reformer 30 Air humidifier 40 Evaporator 50 Recovery water tank 51 Temperature sensor 60 Water storage tank 61 Temperature sensor 62 Water level sensor 71 On-off valve (for recovery water discharge)
72 Electric heater 73 Cooler 74 Water treatment device 75 Pump

Claims (6)

A fuel cell main body, a cooling water circulation passage through which cooling water for cooling the fuel cell main body flows, a reformer for steam-reforming raw fuel to generate fuel gas to be supplied to the fuel cell main body, A recovered water tank for recovering the generated water by introducing at least one of off-gas containing reaction product water discharged from the fuel cell main body and exhaust gas containing combustion product water discharged from the reformer, and the recovered water In a fuel cell power generator comprising a water storage tank that stores water sent from a tank and supplies the stored water to at least one of the cooling water circulation channel and the reformer, the water is recovered in the recovered water tank. A fuel cell power generator comprising: a heating means for heating the water flowing through the flow path in a flow path for sending the recovered water to the water storage tank through an on-off valve. The cooling means for cooling the water flowing through the flow path is provided on the downstream side of the heating means of the flow path for sending the recovered water from the recovered water tank to the water storage tank through the on-off valve. Item 4. The fuel cell power generator according to Item 1. Drive means for driving the water flowing through the flow path from the recovered water tank to the water storage tank on the downstream side of the heating means of the flow path for sending the recovered water from the recovered water tank to the water storage tank through the on-off valve The fuel cell power generator according to claim 1, wherein the fuel cell power generator is provided. The temperature sensor for detecting the temperature of the recovered water is provided in the recovered water tank, and the temperature sensor for detecting the temperature of the stored water and the water level sensor for detecting the water level are provided in the water storage tank. Item 4. The fuel cell power generator according to any one of Items 1 to 3. When the water level in the water storage tank detected by the water level sensor is below a predetermined water level, the open / close valve is held open to allow the recovered water to flow, and further, detected by the temperature sensor in the recovery water tank The water quality management method for a fuel cell power generator according to claim 4, wherein when the temperature is not more than a first predetermined temperature, the heating means is operated to heat and sterilize the recovered water. When the water level in the water storage tank detected by the water level sensor is below a predetermined water level, the open / close valve is held open to allow the recovered water to flow, and further, detected by the temperature sensor in the recovery water tank When the measured temperature is equal to or lower than the first predetermined temperature and the temperature detected by the temperature sensor in the water storage tank is equal to or lower than the second predetermined temperature, the heating means is operated to heat and sterilize the recovered water. The water quality management method for a fuel cell power generator according to claim 4.

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