JPH0922715A - Power generating device by fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power-generating device with which the pressure in a water-vapor separator is controlled stably and which is equipped with a cooling system to cool the body of fuel cell stably. SOLUTION: A cooling line is structured on such a system that water stored in a water-vapor separator 3 is sent to a body 1 of a fuel cell by a cooling water circulating pump 4 and pressurized water or a gas/liquid flow produced by heating is fed back to a gas phase part of the separator 3. In this cooling line, a cooling water heating unit 11 is installed between the pump 4 and the fuel cell body 1 and another cooling water heating unit 6 is furnished between the fuel cell body 1 on the outlet side and the separator 3, and heating is made with the heating unit 11 when vapor quantity on the outlet side exceeds the specified level, and thereby the pressure of the separator 3 is controlled stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cooling system for removing heat generation of a fuel cell main body of a fuel cell power generator and keeping it at a predetermined temperature.

[0002]

2. Description of the Related Art A fuel cell power generator supplies hydrogen obtained by steam reforming a raw fuel such as LNG and oxygen in the air to a fuel electrode and an air electrode of a fuel cell body, respectively.
Electricity is generated by an electrochemical reaction.In a phosphoric acid fuel cell power generator, the heat generated by power generation is removed by supplying cooling water to maintain the operating temperature of the fuel cell main body at a constant temperature and to generate heat. Are collected and are effectively used.

FIG. 4 is a system diagram showing a basic configuration of a cooling system of a fuel cell main body of a fuel cell power generator which has been conventionally used. In the figure, the fuel cell body 1 is schematically shown, and an electrolyte layer (not shown) is sandwiched between a fuel electrode and an air electrode to form a unit cell, and a cooling pipe is provided for each stack of a plurality of unit cells. The cooling plate 2 is arranged.

Raw fuel such as LNG is sent to the ejector 7 and mixed with high-pressure steam sent from the steam separator 3 through the process steam valve 9, and then the fuel reformer 8 is supplied.
Is supplied to the fuel electrode of the fuel cell main body 1 after steam reforming. In order to stably continue the reforming reaction, it is an essential condition that the raw fuel and high-pressure steam are stably supplied.

The cooling water from the steam separator 3 is sent to the cooling pipe provided in the cooling plate 2 of the fuel cell body 1 by the cooling water circulation pump 4. Pressurized water, which is obtained by removing the heat generated by power generation and cooled to obtain high temperature, or the cooling water having a gas-liquid two-phase flow composed of water and steam, is used as the heat recovery heat exchanger 5 and the cooling water heater. It is returned to the vapor phase part of the steam separator 3 via 6.

The heat recovery heat exchanger 5 is for recovering the heat stored in the pressurized water or the gas-liquid two-phase cooling water discharged from the fuel cell body 1, and supplies the secondary cooling water. Heat is recovered to the outside by controlling the pressure of the steam separator 3 to be constant, thereby stabilizing the supply amount of high-pressure steam to the ejector 7 and keeping the temperature of the cooling water sent to the fuel cell main body 1 constant. Has a role to hold.

The cooling water heater 6 is installed for compensation at the time of start-up and at the time of pressure drop of the steam separator 3, is constructed by incorporating an electric heater, and can be operated from a low temperature state at start-up. When the temperature is raised to a certain temperature, or when the heat balance is lost during operation and the pressure of the steam separator 3 is reduced, the electric heater is energized to raise the temperature and the amount of vapor is increased to raise the pressure. It plays a role. In the cooling system shown in FIG. 4, the cooling water heater 6 is installed in the return pipe of the fuel cell main body 1 of the cooling water. However, a system in which the cooling water heater 6 is attached inside the water vapor separator 3 is adopted. There are also cases.

Further, the water vapor separator 3 sends the cooling water to the fuel cell main body 1 to supply the high pressure water vapor to the ejector 7 as described above, and a part of the high pressure water vapor is passed through the external steam extraction valve 10. It is taken out to the outside and sent to, for example, an absorption refrigerator or a heat exchanger for hot water supply to be used for heat. Therefore, if the cooling system configured as described above is provided, the fuel cell body 1 is stably cooled by the cooling water held at a constant temperature, the high-pressure steam is stably supplied to the ejector 7, and the reaction production is further performed. Effective use of heat will be achieved.

[0009]

However, even in the fuel cell power generator having the cooling system configured as described above, the pressure of the water vapor separator 3 may drop when the amount of power generation is large and the amount of generated heat is large. If it occurs, there is a risk that the cooling water heater 6 using an electric heater may be locally heated and damaged, and further, the cooling performance may decrease and the temperature of the fuel cell body 1 may rise.

That is, when the amount of power generation increases from the normal operating state and the amount of heat generated increases accordingly, the ratio of the vapor of the cooling water in the gas-liquid two-phase flow discharged from the fuel cell body 1 becomes high. . At this time, if a situation occurs where the pressure of the steam separator 3 decreases due to fluctuations in the amount of steam extracted to the outside, for example, the electric heater is energized to keep the pressure, and the cooling water heater 6 operates. However, since the proportion of steam is high, the electric heater to be energized causes local heating in a portion existing in the steam, and there is a risk of damage due to thermal stress. Further, a large amount of steam is partially generated to increase the pressure loss of the cooling water circulation system, and accordingly, the discharge amount of the cooling water circulation pump 4 decreases, and the proportion of steam progressively increases to increase the fuel cell main body. There is a risk that the supply of cooling water to the fuel cell unit 1 will be insufficient and the temperature of the fuel cell body 1 will rise.

Further, in the case of a system in which steam is supplied from the steam separator 3 to an external absorption refrigerator or a heat exchanger for hot water supply via the external steam extraction valve 10 in order to utilize heat, Normally, it is necessary to supply a large amount of water vapor to the outside even when the amount of power generation is low, and as in the above case, the required heat generation amount of the cooling water heater 6 increases, causing the local heating of the electric heater as described above. However, there is a possibility that the cooling performance may be deteriorated.

The present invention solves the above problems and provides a highly reliable fuel cell power generator having a cooling system in which the pressure of the steam separator is stably controlled and the fuel cell main body is stably cooled. To provide.

[0013]

In order to achieve the above object, in the present invention, (1) a steam separator and water stored in the steam separator are used as fuel in a cooling line for removing heat generation of a fuel cell main body. In a fuel cell power generator having a cooling water circulation pump for sending pressurized water or a gas-liquid two-phase flow generated by heating to a cell body to a vapor phase of a steam separator, a cooling water circulation pump to which cooling water is supplied and a fuel cell body A cooling water heater is provided between the fuel cell main body and the steam separator in which the pressurized water or the gas-liquid two-phase flow flows.

(2) Alternatively, a cooling water heater having an oil circulation type heating means is provided between the fuel cell main body through which pressurized water or gas-liquid two-phase flow flows and the steam separator. (3) Further, a cooling water heater is provided between the cooling water circulation pump to which the cooling water is supplied and the fuel cell main body, and between the fuel cell main body through which the pressurized water or the gas-liquid two-phase flow flows and the steam separator. In the fuel cell power generator, the cooling water heater provided between the fuel cell main body through which pressurized water or gas-liquid two-phase flow flows and the steam separator is a cooling water heater provided with an oil circulation type heating means.

(4) Furthermore, the cooling water heater provided in (2) or (3) above has a circulation system for branching the oil circulation type heating means of the cooling water heater from an oil circulation device having a closed loop oil circulation circuit. Shall be.

[0016]

As described in (1) above, the first cooling water heater is provided between the cooling water circulation pump to which the cooling water is supplied and the fuel cell main body, and the fuel cell main body in which pressurized water or gas-liquid two-phase flow flows. If a second cooling water heater is provided between the steam separator and the steam separator, the pressure of the cooling line and thus the steam separator can be controlled by the two cooling water heaters. Therefore, the pressure in normal operation is controlled using the first cooling water heater, and when the amount of water vapor reaches a predetermined value or higher due to high load, etc., it is controlled using the second cooling water heater. By doing so, local heating in the first cooling water heater is prevented and a required pressure is obtained. Even if heat is input using the second cooling water heater arranged on the inlet side of the fuel cell body as described above, the heat capacity of the fuel cell body is large, so there is no risk of a temperature rise in a short time. By reducing the temperature output or the amount of steam taken out to the outside, the heat balance is restored and the constant pressure control of the steam separator becomes possible.

Further, as described in (2) above, if a cooling water heater having an oil circulation type heating means is provided between the fuel cell main body through which pressurized water or gas-liquid two-phase flow flows and the steam separator. When the oil temperature is controlled to 200 to 350 ° C., a predetermined pressure control can be performed, so local heating such as electric heater type heating is avoided and local generation of water vapor is also prevented.

Further, according to the above (3), the cooling water heater provided with the oil circulation type heating means provided between the fuel cell body and the water vapor separator is provided at the inlet side of the fuel cell body. Since it is backed up by the provided cooling water heater, the burden is reduced and more stable operation becomes possible. Further, as described in (4) above, if the oil circulation type heating means of the cooling water heater has a circulation system branched from an oil circulation device having a closed loop oil circulation circuit,
If the oil heated to a constant temperature is constantly circulated in a closed loop oil circulation circuit, and when it is necessary to heat the cooling water heater, it can be diverted by valve operation and sent to the cooling water heater.
Since the heating at the predetermined temperature can be instantaneously performed, the pressure of the steam separator can be stably controlled without causing a time delay.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing a basic configuration of a cooling system of a fuel cell main body showing a first embodiment of a fuel cell power generator of the present invention. In the figure, components having the same functions as those of the conventional example shown in FIG. The difference between this embodiment and the conventional example is that the steam separator 3
The cooling water heater 11 is installed between the cooling water circulation pump 4 that circulates and supplies the cooling water from the fuel cell body 1.

In this configuration, when the amount of the cooling water vapor reaches a predetermined value or more and it is necessary to raise the pressure of the steam separator 3, the differential pressure gauge 12 causes the differential pressure of the cooling water heater 6 to rise. Or the temperature of the outlet water of the cooling water heater 6 is measured by the thermometer 13 to detect the condition, and the cooling water is heated by the cooling water heater 11 to increase the pressure. Therefore, since it is not necessary to excessively heat the cooling water heater 6, the pressure of the water vapor separator 3 can be stably controlled without fear of local heating or damage due to thermal stress. Even if heat is input using the cooling water heater 11 on the inlet side of the fuel cell body 1 as described above, the heat capacity of the fuel cell body 1 is extremely large, so there is no risk of causing a temperature rise in a short time. By reducing the temperature output or the amount of steam taken out to the outside, the heat balance is restored and the pressure of the steam separator 3 can be controlled to be constant.

FIG. 2 shows a second embodiment of the fuel cell power generator of the present invention.
3 is a system diagram showing a basic configuration of a cooling system of the fuel cell body showing the embodiment of FIG. The difference between the present embodiment and the conventional example is that, instead of the conventional electric heater type cooling water heater 6, an oil circulation is provided between the fuel cell body 1 and the steam separator 3 in which pressurized water or gas-liquid two-phase flow flows. A cooling water heater 14 is provided, and further, between the cooling water circulation pump 4 and the fuel cell body 1,
The cooling water heater 11 is installed, and the oil heated by the oil heater 16 is sent to the cooling water heater 14 by the oil circulation pump 15.

In this configuration, even when the amount of the cooling water vapor reaches a predetermined value or more and the pressure of the steam separator 3 needs to be raised, the oil temperature is set to 2 as described above.
When the steam separator 3 is controlled to be used at a temperature of 00 to 350 ° C., the pressure of the steam separator 3 can be controlled. Therefore, local heating such as heating by an electric heater is avoided, and local generation of steam is prevented. In this embodiment, since the cooling water heater 11 is installed and the operation of the oil circulation type cooling water heater 14 is backed up, the burden is reduced and more stable operation is possible. .

FIG. 3 shows a second embodiment of the fuel cell power generator of the present invention.
3 is a system diagram showing a basic configuration of a cooling system of the fuel cell body showing the embodiment of FIG. In the present embodiment, in the configuration of FIG. 3, the oil heater 1 for supplying heating oil to the oil circulation type cooling water heater 14.
It is characterized in that a three-way valve 17 is further added to the oil circulation device constituted by 6 and the oil circulation pump 15 to provide a closed loop oil circulation circuit.

In this structure, the oil heated to a constant temperature is constantly circulated in the closed loop oil circulation circuit constituted by the oil heater 16, the oil circulation pump 15 and the three-way valve 17, and the cooling water heater is used. When it is necessary to heat 14, the oil circulation cooling water heater 14 can be instantly heated to a predetermined temperature by operating the three-way valve 17 and branching it to the cooling water heater 14. Therefore, the pressure of the steam separator 3 can be stably controlled without causing a time delay due to the temperature rise of the oil heating medium.

[0025]

As described above, according to the present invention, (1) the steam separator and the stored water of the steam separator are sent to the fuel cell main body through the cooling line for removing the heat generation of the fuel cell main body, and by heating. In a fuel cell power generator having a cooling water circulation pump that circulates the generated pressurized water or a gas-liquid two-phase flow into the vapor phase of a steam separator, between the cooling water circulation pump and the fuel cell main body to which cooling water is supplied, and the pressurized water or Since a cooling water heater was provided between the main body of the fuel cell in which the gas-liquid two-phase flow and the steam separator, respectively, the cooling line and hence the pressure of the steam separator are controlled by the two cooling water heaters. It becomes possible to
Even if the amount of water vapor reaches a certain value due to high load, the pressure of the water vapor separator can be controlled normally by controlling it using the cooling water heater installed between the cooling water circulation pump and the fuel cell body. Therefore, the pressure of the water vapor separator is stably controlled, and a highly reliable fuel cell power generator having a cooling system for stably cooling the fuel cell main body can be obtained.

(2) Further, if a cooling water heater having an oil circulation type heating means is provided between the fuel cell main body through which pressurized water or gas-liquid two-phase flow flows and the steam separator, the oil temperature can be increased. Since a predetermined pressure can be controlled by controlling it to an appropriate temperature, the pressure of the water vapor separator can be controlled stably, and the fuel cell main body can be cooled stably. It is suitable as a power generator.

(3) Further, the cooling water is heated between the cooling water circulation pump to which the cooling water is supplied and the fuel cell main body, and between the fuel cell main body and the steam separator in which the pressurized water or the gas-liquid two-phase flow flows. In a fuel cell power generator equipped with
If the cooling water heater provided between the fuel cell body and the water vapor separator is a cooling water heater having an oil circulation type heating means, a cooling water heater having an oil circulation type heating means is provided. Is backed up by the cooling water heater installed on the inlet side of the fuel cell main unit, which reduces the burden and enables more stable operation, so the pressure of the steam separator can be controlled stably. Therefore, the fuel cell main body is more suitable as a highly reliable fuel cell power generator provided with a cooling system that stably cools the fuel cell body.

(4) Further, the cooling water heater according to the above (2) or (3) is provided with a circulation system for branching the oil circulation type heating means from an oil circulation device provided with a closed loop oil circulation circuit. If so, the oil heated to a constant temperature is constantly circulated in a closed loop oil circulation circuit, and when heating of the cooling water heater is required, it is split by valve operation and sent to the cooling water heater. By adopting, it becomes possible to instantly heat at a predetermined temperature, so that the pressure of the steam separator can be controlled stably without causing a time delay, and the pressure of the steam separator can be controlled stably. Therefore, the fuel cell main body is more suitable as a highly reliable fuel cell power generator provided with a cooling system that stably cools the fuel cell body.

[Brief description of drawings]

FIG. 1 is a system diagram showing a basic configuration of a cooling system of a fuel cell body showing a first embodiment of a fuel cell power generator of the present invention.

FIG. 2 is a system diagram showing a basic configuration of a cooling system of a fuel cell body showing a second embodiment of the fuel cell power generator of the present invention.

FIG. 3 is a system diagram showing a basic configuration of a cooling system of a fuel cell main body showing a third embodiment of the fuel cell power generator of the present invention.

FIG. 4 is a system diagram showing a basic configuration of a cooling system of a fuel cell main body of a fuel cell power generator that has been conventionally used.

[Explanation of symbols]

 1 Fuel Cell Main Body 2 Cooling Plate 3 Steam Separator 4 Cooling Water Circulation Pump 5 Heat Recovery Heat Exchanger 6 Cooling Water Heater 7 Ejector 8 Fuel Reformer 9 Process Steam Valve 10 External Steam Extraction Valve 11 Cooling Water Heater 12 Difference Pressure gauge 13 Thermometer 14 Oil circulation type cooling water heater 15 Oil circulation pump 16 Oil heater 17 Three-way valve

Claims (4)

[Claims] 1. A steam separator and water stored in the steam separator are sent to the fuel cell main body in a cooling line for removing heat generation of the fuel cell main body, and pressurized water or a gas-liquid two-phase flow generated by heating is supplied to the steam separator. In a fuel cell power generator having a cooling water circulation pump that circulates into a phase, between a cooling water circulation pump and a fuel cell main body through which cooling water flows, and between a fuel cell main body and a water vapor separator between which pressurized water or a gas-liquid two-phase flow flows A fuel cell power generator characterized in that a cooling water heater is provided between each. 2. A steam separator and water stored in the steam separator are sent to the fuel cell main body in a cooling line for removing heat generation of the fuel cell main body, and pressurized water or a gas-liquid two-phase flow generated by heating is supplied to the steam separator. In a fuel cell power generation device having a cooling water circulation pump that circulates into a phase, a cooling water heater including an oil circulation type heating means is provided between a fuel cell main body through which pressurized water or a gas-liquid two-phase flow flows and a steam separator. A fuel cell power generation device characterized by being provided. 3. The fuel cell power generator according to claim 1, wherein the cooling water heater provided between the cooling water circulation pump through which the cooling water flows and the fuel cell main body is provided with an oil circulation type heating means. A fuel cell power generator characterized by being a heater. 4. The fuel cell power generator according to claim 2 or 3, wherein the oil circulation type heating means has a circulation system branched from the oil circulation device having a closed loop oil circulation circuit. And a fuel cell power generator.