JPH0935733A - Fuel cell power generating plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power generating plant with compact size, low price, and high performance as a co-generation system, capable of conducting supply and stop of exhaust energy of cooling water without increasing equipment such as a condenser. SOLUTION: When steam is not supplied to a steam utilizing device 3 from a steam separator 2, a plant cooling control valve 20 is switched so that plant cooling water can be supplied to a heat exchanging piping 19. A control device 14 adjusts the plant cooling control valve 20 so that cooling water temperature detected with a steam separator temperature detecting device 15 is kept in the specified value, and controls the flow rate of the plant cooling water supplied to the heat exchanging piping 19. When exhaust energy is not supplied to the steam utilizing device 3, the temperature of the steam separator 2 is desirably kept, and the steam separator 2 is cooled with the cooling water of a plant cooling system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention separates exhaust cooling water from a fuel cell main body into water and steam by a steam separator, and uses a part of steam generated by the steam separator in steam utilization equipment. Fuel cell power plant.

[0002]

2. Description of the Related Art Generally, a fuel cell power generation plant continuously supplies a fuel and an oxidant from the outside of the cell to directly convert chemical energy generated by the oxidation of the fuel into electric energy.

This fuel cell power plant is generally shown in FIG.
As shown in FIG. 1, a fuel cell body 1 that generates electric energy from a fuel and an oxidant and cools reaction heat at that time with cooling water, and waste cooling water that has cooled the fuel cell body 1 is separated into water and steam. A steam water separator 2, a steam utilization facility 3 that uses the steam from the steam water separator 2, and a plant cooling system 4 that cools the steam water separator 2, and the water separated by the steam water separator 2 is used as a fuel cell. The main body 1 is supplied with cooling water. In this way, a part of the steam generated by the brackish water separator 2 is used for so-called cogeneration such as cooling and heating.

That is, the fuel cell body 1 for generating an electric current by a chemical reaction is provided with a cell cooling pipe 5 for cooling the fuel cell body 1. The fuel cell main body 1 includes a fuel electrode and an oxidant electrode (not shown). Fuel such as hydrogen generated from methane gas or methyl alcohol is supplied to the fuel electrode through a fuel conduit 6, and the oxidant electrode is connected to the oxidant conduit. Oxidants such as oxygen and air are supplied through 7. After the fuel and the oxidant react in the fuel cell body 1, exhaust fuel,
It becomes exhausted oxidant and is discharged through the conduits 6a and 7a.

Cooling water is supplied to the battery cooling pipe 5 from a cooling water supply source 9 through a cooling water inlet pipe 10 by a cooling water circulation pump 8. The discharged cooling water from the fuel cell body 1 is sent to the brackish water separator 2 through the cooling water outlet pipe 11. The steam separated by the brackish water separator 2 is sent to the fuel reforming system 12 and the steam utilizing facility 3 of the fuel cell plant, and the separated water is returned to the cooling water supply source 9.

A control valve 13 is provided on a pipe for supplying steam to the steam utilizing facility 3, and the control device 14 adjusts the opening of the control valve 13 to discharge the steam to the steam utilizing facility 3. The amount of hot steam supplied is controlled to maintain the temperature of the brackish water separator 2 at a predetermined value. In the control device 14, the deviation between the temperature of the brackish water separator 2 detected by the temperature detector 15 and the set value is calculated by PI control to control the valve 13
The valve opening of is being adjusted.

When the steam utilization equipment 3 does not need to supply steam, the steam from the steam separator 2 cannot be supplied to the steam utilization equipment 3, so the control valve 13 is closed and the steam separator 2 is used. The generated steam is guided to the condenser 16, and heat exchange is performed with the cooling water from the plant cooling system 4, and the heat is returned to the cooling water supply source 9. In this case, the amount of vapor supplied to the condenser 16 is adjusted by the condensation control valve 17.

FIG. 12 is a block diagram of the controller 14. The cooling water temperature of the brackish water separator 2 is detected by the brackish water separator temperature detector 15 as a brackish water separator temperature, and is compared with a preset set value. And the temperature deviation is the first
Input to the second PI controller 18b and the second PI controller 18b. When the steam utilization equipment 3 needs to supply steam, the condensation control valve 17 is closed, the control valve 13 is adjusted by the command signal from the first PI controller 18a, and the steam separator 2 is operated. The temperature is controlled to maintain the set value.
On the other hand, when the steam utilizing facility 3 does not need to supply steam, the control valve 13 is closed, the condensation control valve 17 is adjusted by the command signal from the second PI controller 18b, and the temperature of the steam separator 2 is adjusted. Is controlled to maintain the set value.

[0009]

However, as described above,
In the configuration in which the steam is directly taken out from the brackish water separator 2 and the waste energy is recovered by the steam utilizing facility 3, the steam may not be required due to the operational convenience of the steam utilizing facility 3. That is, there are times when steam cannot be sent from the brackish water separator 2.
In this case, a condenser 16 for condensing steam by the plant cooling system 4 and a condensation control valve 17 had to be installed as a backup of the steam utilization facility 3 and the control valve 13 in order to maintain the brackish water separator temperature.

Therefore, an object of the present invention is to provide a compact and inexpensive fuel cell power plant as a cogeneration capable of supplying and stopping the exhaust energy of cooling water without increasing the number of devices such as condensers. Is.

[0011]

According to a first aspect of the present invention, there is provided a fuel cell main body for generating electric energy from a fuel and an oxidant and cooling reaction heat at that time with cooling water, and an exhaust gas for cooling the fuel cell main body. It is equipped with a brackish water separator that separates cooling water into water and steam, steam utilization equipment that uses the steam from the brackish water separator, and a plant cooling system that cools the brackish water separator. A fuel cell power plant for supplying cooling water to the fuel cell main body, which is provided in the brackish water separator and has heat exchange piping for exchanging heat with the plant cooling water from the plant cooling system, and steam utilization equipment. When the steam from the brackish water separator is not supplied to the plant, the plant cooling control valve for switching the plant cooling water to the heat exchange pipe and adjusting the amount of plant cooling water, and the inside of the brackish water separator Brackish water separator temperature detector that detects the cooling water temperature, and so that the cooling water temperature detected by the brackish water separator temperature detector is maintained at a specified value when steam from the brackish water separator is not supplied to the steam utilization facility. And a controller for controlling the flow rate of the plant cooling water supplied to the heat exchange pipe by adjusting the plant cooling control valve.

According to a second aspect of the present invention, a fuel cell main body for generating electric energy from a fuel and an oxidizer and cooling reaction heat at that time with cooling water, and waste cooling water for cooling the fuel cell main body with water and steam. It is equipped with a brackish water separator that separates into steam, steam utilization equipment that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator. In the fuel cell power plant, the heat exchange pipe is provided in the brackish water separator for exchanging heat with the plant cooling water from the plant cooling system, and the steam utilization facility is equipped with a heat exchange pipe from the brackish water separator. When steam is not supplied, switch to supply plant cooling water to the heat exchange pipe and detect the plant cooling control valve to adjust the amount of plant cooling water and the steam pressure in the brackish water separator. Brackish water separator pressure detector and plant cooling control valve to keep the steam pressure detected by the brackish water separator pressure detector at a specified value when steam from the brackish water separator is not supplied to the steam utilization facility. And a control device that controls the flow rate of the plant cooling water that is adjusted and supplied to the heat exchange pipe.

According to a third aspect of the present invention, a fuel cell main body for generating electric energy from a fuel and an oxidant and cooling reaction heat at that time with cooling water, and waste cooling water for cooling the fuel cell main body with water and steam. It is equipped with a brackish water separator that separates into steam, steam utilization equipment that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator. In the fuel cell power plant, the heat exchange pipe is provided in the brackish water separator for exchanging heat with the plant cooling water from the plant cooling system, and the steam utilization facility is equipped with a heat exchange pipe from the brackish water separator. When steam is not supplied, the plant cooling water is switched to supply the plant cooling water to the heat exchange pipe, and the plant cooling control valve for adjusting the amount of plant cooling water and the exhaust cooling water temperature at the outlet of the fuel cell main unit And discharge the cooling water temperature detector for detecting,
When the steam from the brackish water separator is not supplied to the steam utilization facility, the plant cooling control valve is adjusted so that the exhaust cooling water temperature detected by the exhaust cooling water temperature detector is maintained at a specified value and supplied to the heat exchange pipe. And a control device that controls the flow rate of the plant cooling water.

According to a fourth aspect of the present invention, a fuel cell main body for generating electric energy from a fuel and an oxidant and cooling reaction heat at that time with cooling water, and waste cooling water for cooling the fuel cell main body with water and steam. It is equipped with a brackish water separator that separates into steam, steam utilization equipment that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator. In the fuel cell power plant, the heat exchange pipe is provided in the brackish water separator for exchanging heat with the plant cooling water from the plant cooling system, and the steam utilization facility is equipped with a heat exchange pipe from the brackish water separator. When steam is not supplied, the plant cooling water is switched to supply heat to the heat exchange pipe, and a plant cooling control valve for adjusting the amount of plant cooling water and exhaust cooling water pressure at the outlet of the fuel cell main unit And discharge cooling water pressure detector for detecting,
When steam from the brackish water separator is not supplied to the steam utilization equipment, the plant cooling control valve is adjusted so that the exhaust cooling water pressure detected by the exhaust cooling water pressure detector is maintained at a specified value and supplied to the heat exchange pipe. And a control device that controls the flow rate of the plant cooling water.

According to a fifth aspect of the present invention, a fuel cell main body for generating electric energy from a fuel and an oxidant and cooling reaction heat at that time with cooling water, and waste cooling water for cooling the fuel cell main body with water and steam. It is equipped with a brackish water separator that separates into steam, steam utilization equipment that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator. In the fuel cell power plant, the heat exchange pipe is provided in the brackish water separator for exchanging heat with the plant cooling water from the plant cooling system, and the steam utilization facility is equipped with a heat exchange pipe from the brackish water separator. When steam is not supplied, the plant cooling control valve for switching to supply the plant cooling water to the heat exchange piping and adjusting the plant cooling water amount, and the battery that is the output of the fuel cell body The battery current detector that detects the flow of electricity and the cooling water temperature inside the brackish water separator is set to a predetermined value based on the battery current detected by the battery current detector when the steam from the brackish water separator is not supplied to the steam utilization facility. A control device that adjusts the plant cooling control valve so as to be maintained and controls the flow rate of the plant cooling water supplied to the heat exchange pipe.

According to a sixth aspect of the present invention, a fuel cell main body for generating power by an electrochemical reaction between a fuel and an oxidant, a cooling water circulation pump for supplying cooling water for cooling the fuel cell main body to the fuel cell main body, and a fuel A steam separator that separates the waste cooling water that has cooled the battery body into water and steam, and heat exchange pipes that are placed in the steam separator to exchange heat with the water in the steam separator and cool this water. It is equipped with and.

According to a seventh aspect of the invention, in the sixth aspect of the invention, a steam utilizing facility that uses the steam from the steam separator is provided.
A plant cooling water control valve is provided for cooling the water in the steam / water separator by heat exchange through the heat exchange pipe when steam from the steam / water separator is not supplied to the steam utilization facility.

The invention of claim 8 is claim 6 or claim 7.
In the invention of, the control device for controlling the heat exchange amount by the heat exchange pipe is provided so that the predetermined process state amount maintains a predetermined set value when the steam from the steam separator is not supplied to the steam utilization facility. It is a thing.

According to the first aspect of the invention, when the steam from the steam separator is not supplied to the steam utilizing facility, the plant cooling control valve is switched so that the plant cooling water can be supplied to the heat exchange pipe. Then, the control device adjusts the plant cooling control valve so that the cooling water temperature detected by the brackish water separator temperature detector is maintained at a predetermined value, and controls the flow rate of the plant cooling water supplied to the heat exchange pipes. To do. Thus, when the exhaust energy is not supplied from the fuel cell power plant to the steam utilization facility, the brackish water separator is cooled by the cooling water of the plant cooling system to maintain the temperature of the brackish water separator at a desired temperature. Therefore, no capacitor is needed.

In the second aspect of the present invention, when the steam from the steam separator is not supplied to the steam utilizing facility, the plant cooling control valve is switched so that the plant cooling water can be supplied to the heat exchange pipe. Then, the control device adjusts the plant cooling control valve so that the steam pressure in the brackish water separator detected by the brackish water separator pressure detector is maintained at a predetermined value, and the plant cooling water supplied to the heat exchange pipe is adjusted. Control the flow rate of. Thus, when exhaust energy is not supplied from the fuel cell power plant to the steam utilization facility, the brackish water separator is cooled by the cooling water of the plant cooling system to maintain the pressure of the brackish water separator at a desired pressure. Therefore, no capacitor is needed.

In the third aspect of the present invention, when the steam from the steam separator is not supplied to the steam utilizing facility, the plant cooling control valve is switched so that the plant cooling water can be supplied to the heat exchange pipe. Then, the control device adjusts the plant cooling control valve so that the exhaust cooling water temperature at the outlet of the fuel cell main body detected by the exhaust cooling water temperature detector at the outlet of the fuel cell main body is adjusted to a predetermined value, and the heat exchange pipe is adjusted. Control the flow rate of the plant cooling water supplied to the. As a result, when exhaust energy is not supplied from the fuel cell power plant to the steam utilization facility, the brackish water separator is cooled with the cooling water of the plant cooling system to maintain the temperature of the exhaust cooling water at the outlet of the fuel cell at the desired temperature. To do. Therefore, no capacitor is needed.

In the invention of claim 4, when the steam from the steam separator is not supplied to the steam utilizing facility, the plant cooling control valve is switched so that the plant cooling water can be supplied to the heat exchange pipe. The control device adjusts the plant cooling control valve so that the exhaust cooling water pressure at the outlet of the fuel cell main body detected by the exhaust cooling water pressure detector at the outlet of the fuel cell main body is maintained at a predetermined value, and the heat exchange pipe is adjusted. Control the flow rate of the plant cooling water supplied to the. As a result, when exhaust energy is not supplied from the fuel cell power plant to the steam utilization facility, the brackish water separator is cooled by the cooling water of the plant cooling system to maintain the pressure of the exhaust cooling water at the outlet of the fuel cell at the desired temperature. To do. Therefore, no capacitor is needed.

In the fifth aspect of the invention, when the steam from the steam separator is not supplied to the steam utilizing facility, the plant cooling control valve is switched so that the plant cooling water can be supplied to the heat exchange pipe. Then, the control device controls the plant cooling control valve so that the cooling water temperature in the brackish water separator is maintained at a predetermined value based on the battery current detected by the battery current detector detector which is the output of the fuel cell body. Controls the flow rate of the plant cooling water that is regulated and supplied to the heat exchange pipes. As a result, when exhaust energy is not supplied from the fuel cell power plant to the steam utilization facility, the brackish water separator is cooled by the cooling water of the plant cooling system, and the cooling water temperature in the brackish water separator is maintained at a predetermined value. Therefore, no capacitor is needed.

According to the sixth aspect of the invention, cooling water for cooling the fuel cell main body that generates electricity by the electrochemical reaction between the fuel and the oxidant is supplied to the fuel cell main body by the cooling water circulation pump to cool the fuel cell main body. The discharged cooling water is separated into water and steam by a steam separator. Then, the heat exchange pipe arranged in the steam separator separates heat from the water in the steam separator to cool the water.

According to the invention of claim 7, in addition to the operation of the invention of claim 6, when the steam from the steam-water separator is not supplied to the steam utilizing facility which uses the steam from the steam-water separator,
The plant cooling water control valve cools the water in the steam separator by heat exchange through the heat exchange pipes.

In the invention of claim 8, in addition to the operation of the invention of claim 6 or claim 7, when the steam from the steam separator is not supplied to the steam utilizing facility, the controller performs a predetermined process. The heat exchange amount through the heat exchange pipe is controlled so that the state quantity maintains a preset value.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing the first embodiment of the present invention. In the first embodiment, a heat exchange pipe 19 for exchanging heat with the plant cooling water from the plant cooling system 4 is provided in the steam separator 2 in the conventional fuel cell power plant shown in FIG. When the steam is not supplied from the brackish water separator 2 to the steam utilization facility 3, the plant cooling control valve 20 is switched to supply the plant cooling water to the heat exchange pipe 19. Adjustment of the valve opening degree of the plant cooling control valve 20 (adjustment of the amount of plant cooling water to the heat exchange pipe 19)
Is controlled by the controller 14 so that the cooling water temperature detected by the brackish water separator temperature detector 15 is maintained at a predetermined value.

In FIG. 1, the fuel is supplied to the fuel cell main body 1 through the fuel conduit 6, and the oxidant is supplied through the oxidant conduit 7. Then, in the fuel cell body 1, an electric current is generated by an electrochemical reaction between the fuel and the oxidant. The fuel cell main body 1 is designed to remove the heat generated by the electrochemical reaction by supplying cooling water to a cooling pipe 5 passing through the inside thereof for cooling. In addition, the fuel cell body 1
The fuel and oxidant that have reacted in the exhaust gas are discharged as exhaust fuel or exhaust oxidant through the outlet fuel conduit 6a and the outlet oxidant conduit 7a.

The cooling water supplied from the cooling water supply source 9 to the fuel cell main body 1 by the cooling water circulation pump 8 is sent to the cell cooling pipe 5 through the cooling water inlet pipe 10. Battery cooling tube 5
The discharged cooling water that has passed through flows into the brackish water separator 2 through the cooling water outlet pipe 11. The steam separated by the brackish water separator 2 is sent to the fuel reforming system 12 of the fuel cell power plant and the steam utilization facility 3 outside the fuel cell power plant, and the separated water is returned to the cooling water supply source 9.

In the brackish water separator 2, the heat exchange pipe 19
Is provided and is joined to the plant cooling water pipe 21 of the plant cooling system 4 via the plant cooling control valve 20 so that heat can be exchanged with the cooling water of the plant cooling system 4. That is, in the brackish water separator 2, a control valve 13 that adjusts the amount of steam supplied to the steam utilization facility 3 when recovering the exhaust energy, and a plant cooling system that exchanges heat with the brackish water separator 2 when the exhaust energy is not recovered. The plant cooling control valve 20 which adjusts the amount of water is provided. It should be noted that the plant cooling control valve 20 may be a three-way valve located at one of the branch points or the merging points of the pipes, or a two-way valve located at two locations of the brackish water separator 2 side and the bypass side. I don't mind. In addition, the branching and merging place is not limited to the inlet pipe, and may be anywhere on the pipe of the plant cooling system.

Next, when the exhaust energy is supplied to the steam utilizing facility 3, the control device 14 controls the opening degree of the control valve 13 so that the brackish water separator temperature becomes the set value. On the other hand, when the control device 14 receives the signal to stop the supply of the exhaust energy to the steam utilization facility 3, the control device 14 closes the control valve 13 and also connects the plant cooling control valve 20 to the heat exchange pipe 19.
, And the valve opening degree of the plant cooling control valve 20 is adjusted so that the brackish water separator temperature is controlled to the set value.

FIG. 2 shows a control device 1 according to the first embodiment.
4 shows a block configuration diagram of No. 4. As shown in FIG. 2, when the exhaust energy is supplied to the steam utilization facility 3, the plant cooling control valve 20 is closed to set the temperature and the steam separator temperature detector 1.
The first PI controller 1 based on the deviation from the detection signal 5
It is converted into an opening signal of the control valve 13 by 8a, and the opening / closing is controlled to an opening according to the temperature of the brackish water separator 2. Then, the temperature of the brackish water separator 2 is maintained at the set temperature by adjusting the exhaust energy supply amount. On the other hand, when receiving a signal to stop the supply of exhaust energy to the steam utilization facility 3, the control device 1
4 closes the control valve 13 and, based on the deviation between the set temperature and the brackish water separator temperature detector 15, the second PI controller 18
It is converted into the opening signal of the plant cooling control valve 20 by b, and the opening / closing is controlled to the opening according to the temperature of the brackish water separator 2.
Then, the temperature of the brackish water separator 2 is maintained at the set value by adjusting the amount of heat exchange between the brackish water separator 2 and the plant cooling system.

The cooling water branched to the heat exchange pipe 19 by the plant cooling control valve 20 flows into the brackish water separator 2 to exchange heat with the battery cooling water and join again into the main stream. In this way, it is determined whether or not to branch a part of the cooling water of the plant cooling system for heat exchange with the brackish water separator 2 depending on whether or not the exhaust energy is supplied to the steam utilization facility 3, and to the steam utilization facility 3. When the exhaust energy supply is not performed, heat exchange is performed with the brackish water separator 2, and the flow rate of cooling water of the plant cooling system that exchanges heat with the brackish water separator 2 is adjusted by the temperature of the brackish water separator 2. Thereby, the temperature control can be performed even when the supply of the exhaust energy of the battery cooling water is stopped.

As is clear from the above description, this first
According to the embodiment described above, the cooling water of the plant cooling system is directly heat-exchanged with the brackish water separator 2 to prevent an increase in the number of devices such as the condenser 16. Further, by detecting the temperature of the brackish water separator 2, opening and closing the plant cooling control valve 20 installed in the plant cooling system pipe according to the detected value, and adjusting the flow rate of the cooling water that exchanges heat with the brackish water separator 2. The temperature of the brackish water separator 2 can be stably maintained according to the set value.

Next, a second embodiment of the present invention will be described.
FIG. 3 is a block diagram of the second embodiment of the present invention. The second embodiment is different from the first embodiment shown in FIG. 1 in that the brackish water separator pressure detector 22 is used instead of the brackish water separator temperature detector 15 to detect the steam pressure in the brackish water separator 2. And the controller 14 controls the steam utilization facility 3 to the brackish water separator 2
When the steam from the plant is not supplied, the plant cooling control valve 20 is adjusted so that the steam pressure detected by the steam separator pressure detector 22 is maintained at a predetermined value, and the plant cooling water supplied to the heat exchange pipe 19 is supplied. The flow rate of is controlled.

In FIG. 3, the fuel is supplied to the fuel cell main body 1 through the fuel conduit 6, and the oxidant is supplied through the oxidant conduit 7. Then, in the fuel cell body 1, an electric current is generated by an electrochemical reaction between the fuel and the oxidant. The fuel cell main body 1 is designed to remove the heat generated by the electrochemical reaction by supplying cooling water to a cooling pipe 5 passing through the inside thereof for cooling. In addition, the fuel cell body 1
The fuel and oxidant that have reacted in the exhaust gas are discharged as exhaust fuel or exhaust oxidant through the outlet fuel conduit 6a and the outlet oxidant conduit 7a.

The cooling water supplied from the cooling water supply source 9 to the fuel cell main body 1 by the cooling water circulation pump 8 is sent to the cell cooling pipe 5 through the cooling water inlet pipe 10. Battery cooling tube 5
The discharged cooling water that has passed through flows into the brackish water separator 2 through the cooling water outlet pipe 11. The steam separated by the brackish water separator 2 is sent to the fuel reforming system 12 of the fuel cell power plant and the steam utilization facility 3 outside the fuel cell power plant, and the separated water is returned to the cooling water supply source 9.

In the brackish water separator 2, the heat exchange pipe 19
Is provided and is joined to the plant cooling water pipe 21 of the plant cooling system 4 via the plant cooling control valve 20 so that heat can be exchanged with the cooling water of the plant cooling system 4. That is, in the brackish water separator 2, a control valve 13 that adjusts the amount of steam supplied to the steam utilization facility 3 when recovering the exhaust energy, and a plant cooling system that exchanges heat with the brackish water separator 2 when the exhaust energy is not recovered. The plant cooling control valve 20 which adjusts the amount of water is provided. It should be noted that the plant cooling control valve 20 may be a three-way valve located at one of the branch points or the merging points of the pipes, or a two-way valve located at two locations of the brackish water separator 2 side and the bypass side. Does not matter. In addition, the branching and merging place is not limited to the inlet pipe, and may be anywhere on the pipe of the plant cooling system.

Next, when the exhaust energy is supplied to the steam utilizing facility 3, the control device 14 adjusts the valve opening of the control valve 13 to control the pressure of the steam separator to the set value. On the other hand, when the control device 14 receives the signal to stop the supply of the exhaust energy to the steam utilization facility 3, the control device 14 closes the control valve 13 and also connects the plant cooling control valve 20 to the heat exchange pipe 19.
, And the valve opening degree of the plant cooling control valve 20 is adjusted to control the brackish water separator pressure to the set value.

FIG. 4 shows the control device 1 according to the second embodiment.
4 shows a block configuration diagram of No. 4. As shown in FIG. 4, when the exhaust energy is supplied to the steam utilizing facility 3, the plant cooling control valve 20 is closed to set the pressure and the steam water separator pressure detector 2.
The first PI controller 18 based on the deviation from the detection signal of 2
It is converted into the opening signal of the control valve 13 by a, and the opening / closing is controlled to the opening according to the pressure of the brackish water separator 2. Then, the pressure of the brackish water separator 2 is maintained at the set pressure by adjusting the exhaust energy supply amount. On the other hand, when receiving a signal to stop the supply of exhaust energy to the steam utilization facility 3, the control device 14
Closes the control valve 13, and based on the deviation between the set pressure and the brackish water separator pressure detector 22, the second PI controller 18
It is converted into the opening signal of the plant cooling control valve 20 by b, and the opening / closing control is performed to the opening according to the pressure of the brackish water separator 2.
Then, the pressure of the brackish water separator 2 is maintained at the set value by adjusting the amount of heat exchange between the brackish water separator 2 and the plant cooling system.

The cooling water branched to the heat exchange pipe 19 by the plant cooling control valve 20 flows into the brackish water separator 2 to exchange heat with the battery cooling water and join again into the main stream. In this way, it is determined whether or not to branch a part of the cooling water of the plant cooling system for heat exchange with the brackish water separator 2 depending on whether or not the exhaust energy is supplied to the steam utilization facility 3, and to the steam utilization facility 3. When the exhaust energy is not supplied, heat is exchanged with the brackish water separator 2, and the cooling water flow rate of the plant cooling system that exchanges heat with the brackish water separator 2 is adjusted by the pressure of the brackish water separator 2. As a result, pressure control can be performed even when the supply of exhaust energy of the battery cooling water is stopped.

As is apparent from the above description, according to the second embodiment, the condenser 16 is directly exchanged with the cooling water in the plant cooling system by the heat exchange with the brackish water separator 2.
It is possible to prevent an increase in equipment such as. Also brackish water separator 2
The pressure of the plant cooling control valve 20 installed in the plant cooling system piping according to the detected value,
By adjusting the flow rate of the cooling water that exchanges heat with the brackish water separator 2, the pressure of the brackish water separator 2 can be stably maintained as set.

Next, a third embodiment of the present invention will be described.
FIG. 5 is a block diagram of the third embodiment of the present invention. The third embodiment differs from the first embodiment shown in FIG. 1 in that instead of the brackish water separator temperature detector 15, an exhaust cooling water temperature detector for detecting the exhaust cooling water temperature at the outlet of the fuel cell main body. Two
3, the control device 14 keeps the exhaust cooling water temperature detected by the exhaust cooling water temperature detector 23 at a predetermined value when the steam utilizing facility 3 is not supplied with steam from the brackish water separator 2. In addition, the plant cooling control valve 20 is adjusted to control the flow rate of the plant cooling water supplied to the heat exchange pipe 19.

In FIG. 5, the fuel is supplied to the fuel cell main body 1 through the fuel conduit 6, and the oxidant is supplied through the oxidant conduit 7. Then, in the fuel cell body 1, an electric current is generated by an electrochemical reaction between the fuel and the oxidant. The fuel cell main body 1 is designed to remove the heat generated by the electrochemical reaction by supplying cooling water to a cooling pipe 5 passing through the inside thereof for cooling. In addition, the fuel cell body 1
The fuel and oxidant that have reacted in the exhaust gas are discharged as exhaust fuel or exhaust oxidant through the outlet fuel conduit 6a and the outlet oxidant conduit 7a.

The cooling water supplied from the cooling water supply source 9 to the fuel cell main body 1 by the cooling water circulation pump 8 is sent to the cell cooling pipe 5 through the cooling water inlet pipe 10. Battery cooling tube 5
The discharged cooling water that has passed through flows into the brackish water separator 2 through the cooling water outlet pipe 11. The steam separated by the brackish water separator 2 is sent to the fuel reforming system 12 of the fuel cell power plant and the steam utilization facility 3 outside the fuel cell power plant, and the separated water is returned to the cooling water supply source 9.

In the brackish water separator 2, the heat exchange pipe 19
Is provided and is joined to the plant cooling water pipe 21 of the plant cooling system 4 via the plant cooling control valve 20 so that heat can be exchanged with the cooling water of the plant cooling system 4. That is, in the brackish water separator 2, a control valve 13 that adjusts the amount of steam supplied to the steam utilization facility 3 when recovering the exhaust energy, and a plant cooling system that exchanges heat with the brackish water separator 2 when the exhaust energy is not recovered. The plant cooling control valve 20 which adjusts the amount of water is provided. It should be noted that the plant cooling control valve 20 may be a three-way valve located at one of the branch points or the merging points of the pipes, or a two-way valve located at two locations of the brackish water separator 2 side and the bypass side. I don't mind. In addition, the branching and merging place is not limited to the inlet pipe, and may be anywhere on the pipe of the plant cooling system.

Next, when the exhaust energy is supplied to the steam utilizing facility 3, the control device 14 adjusts the valve opening degree of the control valve 13 so that the exhaust cooling water temperature at the outlet of the fuel cell main body 1 becomes the set value. Control to be. On the other hand, steam utilization facility 3
When receiving the signal for stopping the supply of exhaust energy to the control device 14, the control device 14 closes the control valve 13, switches the plant cooling control valve 20 to the heat exchange pipe 19, and adjusts the valve opening degree of the plant cooling control valve 20. Then, the temperature of the exhaust cooling water at the outlet of the fuel cell body 1 is controlled so as to reach the set value.

FIG. 6 shows a control device 1 according to the third embodiment.
4 shows a block configuration diagram of No. 4. As shown in FIG. 6, when the exhaust energy is supplied to the steam utilizing facility 3, the plant cooling control valve 20 is closed to set the set temperature and the exhaust cooling water temperature detector 23.
Based on the deviation from the exhaust cooling water temperature at the outlet of the fuel cell main body 1 detected in step 1, the first PI controller 18a converts it into an opening signal of the control valve 13, and at the outlet of the fuel cell main body 1. The opening / closing is controlled to an opening degree according to the temperature of the exhaust cooling water.
Then, the exhaust cooling water temperature at the outlet of the fuel cell body 1 is maintained at the set temperature by adjusting the exhaust energy supply amount. On the other hand, when the control device 14 receives the signal for stopping the supply of the exhaust energy to the steam utilization facility 3, the control device 14 closes the control valve 13 and determines the difference between the set temperature and the exhaust cooling water temperature at the outlet of the fuel cell body 1. And the second PI controller 18
It is converted into the opening signal of the plant cooling control valve 20 by b, and the opening / closing control is performed to the opening degree according to the exhaust cooling water temperature at the outlet of the fuel cell main body 1. Then, by adjusting the amount of heat exchange between the brackish water separator 2 and the plant cooling system, the temperature of the exhaust cooling water at the outlet of the fuel cell main body 1 is maintained at the set value.

The cooling water branched to the heat exchange pipe 19 by the plant cooling control valve 20 flows into the brackish water separator 2 to exchange heat with the battery cooling water and join again into the main stream. In this way, it is determined whether or not to branch a part of the cooling water of the plant cooling system for heat exchange with the brackish water separator 2 depending on whether or not the exhaust energy is supplied to the steam utilization facility 3, and to the steam utilization facility 3. When the exhaust energy supply is not performed, heat exchange with the brackish water separator 2 is performed, and the cooling water flow rate of the plant cooling system that exchanges heat with the brackish water separator 2 is adjusted by the exhaust cooling water temperature at the outlet of the fuel cell body 1. To do. Accordingly, the exhaust cooling water temperature control can be performed even when the supply of the exhaust energy of the battery cooling water is stopped.

As is clear from the above description, this third
According to the embodiment of the above, by directly exchanging heat between the plant cooling water of the plant cooling system 4 and the brackish water separator 2,
It is possible to prevent an increase in devices such as the capacitor 16. Further, the temperature of the exhaust cooling water at the outlet of the fuel cell main body 1 is detected by the exhaust cooling water temperature detector 23, and the plant cooling control valve 2 installed in the plant cooling system pipe according to the detected value.
By opening and closing 0 and adjusting the flow rate of the cooling water that exchanges heat with the brackish water separator 2, the temperature of the exhaust cooling water at the outlet of the fuel cell main body 1 can be stably maintained at the set value.

Next, a fourth embodiment of the present invention will be described.
FIG. 7 is a block diagram of the fourth embodiment of the present invention. The fourth embodiment differs from the first embodiment shown in FIG. 1 in that the steam cooling water temperature detector 15 is replaced by an exhaust cooling water pressure detector for detecting the exhaust cooling water pressure at the outlet of the fuel cell body. Two
4, the control device 14 keeps the exhaust cooling water pressure detected by the exhaust cooling water pressure detector 24 at a predetermined value when the steam from the brackish water separator 2 is not supplied to the steam utilizing facility 3. In addition, the plant cooling control valve 20 is adjusted to control the flow rate of the plant cooling water supplied to the heat exchange pipe 19.

In FIG. 7, fuel is supplied to the fuel cell main body 1 through the fuel conduit 6, and oxidant is supplied through the oxidant conduit 7. Then, in the fuel cell body 1, an electric current is generated by an electrochemical reaction between the fuel and the oxidant. The fuel cell main body 1 is designed to remove the heat generated by the electrochemical reaction by supplying cooling water to a cooling pipe 5 passing through the inside thereof for cooling. In addition, the fuel cell body 1
The fuel and oxidant that have reacted in the exhaust gas are discharged as exhaust fuel or exhaust oxidant through the outlet fuel conduit 6a and the outlet oxidant conduit 7a.

The cooling water supplied from the cooling water supply source 9 to the fuel cell body 1 by the cooling water circulation pump 8 is sent to the cell cooling pipe 5 through the cooling water inlet pipe 10. Battery cooling tube 5
The discharged cooling water that has passed through flows into the brackish water separator 2 through the cooling water outlet pipe 11. The steam separated by the brackish water separator 2 is sent to the fuel reforming system 12 of the fuel cell power plant and the steam utilization facility 3 outside the fuel cell power plant, and the separated water is returned to the cooling water supply source 9.

In the brackish water separator 2, the heat exchange pipe 19
Is provided and is joined to the plant cooling water pipe 21 of the plant cooling system 4 via the plant cooling control valve 20 so that heat can be exchanged with the cooling water of the plant cooling system 4. That is, in the brackish water separator 2, a control valve 13 that adjusts the amount of steam supplied to the steam utilization facility 3 when recovering the exhaust energy, and a plant cooling system that exchanges heat with the brackish water separator 2 when the exhaust energy is not recovered. The plant cooling control valve 20 which adjusts the amount of water is provided. It should be noted that the plant cooling control valve 20 may be a three-way valve located at one of the branch points or the merging points of the pipes, or a two-way valve located at two locations of the brackish water separator 2 side and the bypass side. I don't mind. In addition, the branching and merging place is not limited to the inlet pipe, and may be anywhere on the pipe of the plant cooling system.

Next, when the exhaust energy is supplied to the steam utilizing facility 3, the controller 14 adjusts the valve opening degree of the control valve 13 so that the exhaust cooling water pressure at the outlet of the fuel cell main body 1 becomes the set value. Control to be. On the other hand, steam utilization facility 3
When receiving the signal for stopping the supply of exhaust energy to the control device 14, the control device 14 closes the control valve 13, switches the plant cooling control valve 20 to the heat exchange pipe 19, and adjusts the valve opening degree of the plant cooling control valve 20. Then, the exhaust cooling water pressure at the outlet of the fuel cell body 1 is controlled so as to reach the set value.

FIG. 8 shows a control device 1 according to the fourth embodiment.
4 shows a block configuration diagram of No. 4. As shown in FIG. 8, when the exhaust energy is supplied to the steam utilizing facility 3, the plant cooling control valve 20 is closed to set the set pressure and the exhaust cooling water pressure detector 24.
Based on the deviation from the exhaust cooling water pressure at the outlet of the fuel cell body 1 detected in step 1, the first PI controller 18a converts it into an opening signal of the control valve 13, and The opening / closing is controlled to an opening degree according to the exhaust cooling water pressure.
Then, the exhaust cooling water pressure at the outlet of the fuel cell body 1 is maintained at the set pressure by adjusting the exhaust energy supply amount. On the other hand, when the control device 14 receives the signal for stopping the supply of the exhaust energy to the steam utilization facility 3, the control device 14 closes the control valve 13 and determines the difference between the set pressure and the exhaust cooling water pressure at the outlet of the fuel cell body 1. And the second PI controller 18
It is converted into an opening signal of the plant cooling control valve 20 by b, and opening / closing control is performed to an opening degree according to the exhaust cooling water pressure at the outlet of the fuel cell main body 1. Then, by adjusting the heat exchange amount between the brackish water separator 2 and the plant cooling system, the exhaust cooling water pressure at the outlet of the fuel cell main body 1 is maintained at the set value.

The cooling water branched to the heat exchange pipe 19 by the plant cooling control valve 20 flows into the brackish water separator 2 to exchange heat with the battery cooling water and join again into the main stream. In this way, it is determined whether or not to branch a part of the cooling water of the plant cooling system for heat exchange with the brackish water separator 2 depending on whether or not the exhaust energy is supplied to the steam utilization facility 3, and to the steam utilization facility 3. When the exhaust energy is not supplied, heat exchange with the brackish water separator 2 is performed, and the cooling water flow rate of the plant cooling system that exchanges heat with the brackish water separator 2 is adjusted by the exhaust cooling water pressure at the outlet of the fuel cell body 1. To do. Accordingly, the exhaust cooling water pressure control can be performed even when the supply of the exhaust energy of the battery cooling water is stopped.

As is clear from the above description, this fourth
According to the embodiment of the above, by directly exchanging heat between the plant cooling water of the plant cooling system 4 and the brackish water separator 2,
It is possible to prevent an increase in devices such as the capacitor 16. Further, the pressure of the exhaust cooling water at the outlet of the fuel cell main body 1 is detected by the exhaust cooling water pressure detector 24, and the plant cooling control valve 2 installed in the plant cooling system pipe in accordance with the detected value.
By opening and closing 0 and adjusting the flow rate of the cooling water that exchanges heat with the brackish water separator 2, the pressure of the exhaust cooling water at the outlet of the fuel cell main body 1 can be stably maintained at the set value.

Next, a fifth embodiment of the present invention will be described.
FIG. 9 is a block diagram of the fifth embodiment of the present invention. The fifth embodiment differs from the first embodiment shown in FIG. 1 in that the brackish water separator temperature detector 15 is replaced by a cell current detector 2 for detecting the cell current output from the fuel cell body 1.
5, the controller 14 controls the battery current detector 2 when the steam utilizing facility 3 is not supplied with steam from the brackish water separator 2.
Based on the battery current detected in 5, the plant cooling control valve is adjusted so that the cooling water temperature in the brackish water separator 2 is maintained at a predetermined value, and the flow rate of the plant cooling water supplied to the heat exchange pipe is controlled. It is something that is done.

In FIG. 9, the fuel is supplied to the fuel cell main body 1 through the fuel conduit 6, and the oxidant is supplied through the oxidant conduit 7. Then, in the fuel cell body 1, an electric current is generated by an electrochemical reaction between the fuel and the oxidant. The fuel cell main body 1 is designed to remove the heat generated by the electrochemical reaction by supplying cooling water to a cooling pipe 5 passing through the inside thereof for cooling. In addition, the fuel cell body 1
The fuel and oxidant that have reacted in the exhaust gas are discharged as exhaust fuel or exhaust oxidant through the outlet fuel conduit 6a and the outlet oxidant conduit 7a.

The cooling water supplied from the cooling water supply source 9 to the fuel cell main body 1 by the cooling water circulation pump 8 is sent to the cell cooling pipe 5 through the cooling water inlet pipe 10. Battery cooling tube 5
The discharged cooling water that has passed through flows into the brackish water separator 2 through the cooling water outlet pipe 11. The steam separated by the brackish water separator 2 is sent to the fuel reforming system 12 of the fuel cell power plant and the steam utilization facility 3 outside the fuel cell power plant, and the separated water is returned to the cooling water supply source 9.

In the brackish water separator 2, the heat exchange pipe 19
Is provided and is joined to the plant cooling water pipe 21 of the plant cooling system 4 via the plant cooling control valve 20 so that heat can be exchanged with the cooling water of the plant cooling system 4. That is, in the brackish water separator 2, a control valve 13 that adjusts the amount of steam supplied to the steam utilization facility 3 when recovering the exhaust energy, and a plant cooling system that exchanges heat with the brackish water separator 2 when the exhaust energy is not recovered. The plant cooling control valve 20 which adjusts the amount of water is provided. It should be noted that the plant cooling control valve 20 may be a three-way valve located at one of the branch points or the merging points of the pipes, or a two-way valve located at two locations of the brackish water separator 2 side and the bypass side. I don't mind. In addition, the branching and merging place is not limited to the inlet pipe, and may be anywhere on the pipe of the plant cooling system.

Next, when the exhaust energy is supplied to the steam utilizing facility 3, the controller 14 adjusts the valve opening degree of the control valve 13 on the basis of the battery current detected by the battery current detector 25, and the brackish water is discharged. The cooling water temperature in the separator 2 is controlled so as to be maintained at a predetermined value. On the other hand, when receiving the signal for stopping the supply of the exhaust energy to the steam utilization facility 3, the control device 14 closes the control valve 13 and switches the plant cooling control valve 20 to the heat exchange pipe 19. Then, based on the battery current detected by the battery current detector 25, the valve opening degree of the plant cooling control valve 20 is adjusted so that the cooling water temperature in the brackish water separator 2 is maintained at a predetermined value. To do.

FIG. 10 shows a block diagram of the control unit 14 in the fifth embodiment. As shown in FIG. 10, when the exhaust energy is supplied to the steam utilizing facility 3, the plant cooling control valve 20 is closed, and the first function generator 26a based on the battery current detected by the battery current detector 25. Is converted into an opening signal of the control valve 13 to control the cooling water temperature in the brackish water separator 2 to be maintained at a predetermined value. on the other hand,
When receiving the signal for stopping the supply of the exhaust energy to the steam utilization facility 3, the control device 14 closes the control valve 13 and, based on the battery current detected by the battery current detector 25, the second function generator. 26b, it converts into the opening degree signal of the plant cooling control valve 20, and it controls so that the cooling water temperature in the brackish water separator 2 may be maintained at a predetermined value.

As described above, the function generator 26a includes a function for maintaining the cooling water temperature in the brackish water separator 2 at a predetermined value.
That is, the function of the cell current of the fuel cell main body 1 and the valve opening degree of the control valve 13 is predetermined. When the battery current is large, the amount of steam generated in the brackish water separator 2 also increases, so the function setting is made so that the opening degree of the control valve 13 becomes large. Similarly, the function generator 26b has a function for maintaining the temperature of the cooling water in the brackish water separator 2 at a predetermined value, that is,
A function of the cell current of the fuel cell main body 1 and the valve opening degree of the plant cooling control valve 20 is predetermined. In this case as well, when the battery current is large, the amount of steam generated in the brackish water separator 2 also increases, so the function setting is made so that the opening degree of the plant cooling control valve 20 becomes large.

Here, the cooling water branched to the heat exchange pipe 19 by the plant cooling control valve 20 flows into the brackish water separator 2, exchanges heat with the battery cooling water, and joins the main stream again.
In this way, it is determined whether or not to branch a part of the cooling water of the plant cooling system for heat exchange with the brackish water separator 2 depending on whether or not the exhaust energy is supplied to the steam utilization facility 3, and to the steam utilization facility 3. If you do not supply the waste energy of
The flow rate of the cooling water of the plant cooling system that exchanges heat with the brackish water separator 2 and exchanges heat with the brackish water separator 2 is adjusted by the cell current that is the output of the fuel cell 1. This allows
Even when the supply of the exhaust energy of the battery cooling water is stopped, the cooling water temperature in the brackish water separator 2 can be controlled.

In the fifth embodiment, the function generators 26a and 26b have a configuration in which the cooling water temperature is maintained at a predetermined value by a function of the battery current and the cooling water temperature in the steam separator 2. However, as in the second to fourth embodiments,
It may be a function of the battery current and other process state quantities (steam pressure in the steam separator, exhaust cooling water temperature, exhaust cooling water pressure, etc.).

As is apparent from the above description, this fifth
According to the embodiment of the above, by directly exchanging the cooling water of the plant cooling system 4 with the brackish water separator 2, it is possible to prevent an increase in the number of devices such as the condenser 16. Further, by detecting the cell current, opening and closing the plant cooling control valve 20 installed in the plant cooling system pipe according to the detected value, and adjusting the flow rate of the cooling water that exchanges heat with the brackish water separator 2, the fuel cell power plant Process state quantity (for example,
The temperature of the battery cooling water) can be stably maintained.

[0069]

As described above, according to the present invention, the cooling water of the plant cooling system is directly heat-exchanged with the brackish water separator, so that there is no need to provide a device such as a condenser for condensing the battery cooling water. , It is possible to supply or stop exhaust energy to steam utilization equipment. That is, it is possible to provide a fuel cell power generation plant having high performance as a compact and inexpensive cogeneration plant.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of a control device according to the first embodiment of the present invention.

FIG. 3 is a block configuration diagram of a second embodiment of the present invention.

FIG. 4 is a block configuration diagram of a control device according to a second embodiment of the present invention.

FIG. 5 is a block diagram of a third embodiment of the present invention.

FIG. 6 is a block configuration diagram of a control device according to a third embodiment of the present invention.

FIG. 7 is a block diagram of a fourth embodiment of the present invention.

FIG. 8 is a block configuration diagram of a control device according to a fourth embodiment of the present invention.

FIG. 9 is a block configuration diagram of a fifth embodiment of the present invention.

FIG. 10 is a block configuration diagram of a control device according to a fifth embodiment of the present invention.

FIG. 11 is a block diagram of a conventional example.

FIG. 12 is a block configuration diagram of a control device in a conventional example.

[Explanation of symbols]

 1 Fuel Cell Main Body 2 Brackish Water Separator 3 Steam Utilization Facility 4 Plant Cooling System 5 Battery Cooling Pipe 6 Fuel Conduit 7 Oxidizing Agent Pipe 8 Cooling Water Circulation Pump 9 Cooling Water Supply Source 10 Cooling Water Inlet Pipe 11 Cooling Water Outlet Pipe 12 Fuel Reforming System 13 Control valve 14 Control device 15 Brackish water separator temperature detector 16 Condenser 17 Condensation control valve 18 PI controller 19 Heat exchange piping 20 Plant cooling control valve 21 Plant cooling water piping 22 Steam water separator pressure detector 23 Exhaust cooling water temperature Detector 24 Exhaust cooling water pressure detector 25 Battery current detector 26 Function generator

Claims (8)

[Claims] 1. A fuel cell main body that generates electric energy from a fuel and an oxidant and cools reaction heat at that time with cooling water, and brackish water that separates waste cooling water that has cooled the fuel cell main body into water and steam. A separator, a steam utilization facility that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator, and the water separated by the brackish water separator is used as cooling water for the fuel cell body. In the fuel cell power generation plant, the heat exchange pipe for exchanging heat with the plant cooling water from the plant cooling system, which is provided in the brackish water separator, and the brackish water separator in the steam utilization facility. And a plant cooling control valve for controlling the amount of the plant cooling water while switching to supply the plant cooling water to the heat exchange pipe when not supplying steam from the , A brackish water separator temperature detector for detecting the temperature of cooling water in the brackish water separator, and cooling detected by the brackish water separator temperature detector when the steam from the brackish water separator is not supplied to the steam utilization facility A fuel cell power generation system, comprising: a controller for adjusting the plant cooling control valve so that the water temperature is maintained at a predetermined value and controlling the flow rate of the plant cooling water supplied to the heat exchange pipe. plant. 2. A fuel cell main body that generates electric energy from a fuel and an oxidant and cools reaction heat at that time with cooling water, and brackish water that separates waste cooling water that has cooled the fuel cell main body into water and steam. A separator, a steam utilization facility that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator, and the water separated by the brackish water separator is used as cooling water for the fuel cell body. In the fuel cell power generation plant, the heat exchange pipe for exchanging heat with the plant cooling water from the plant cooling system, which is provided in the brackish water separator, and the brackish water separator in the steam utilization facility. And a plant cooling control valve for controlling the amount of the plant cooling water while switching to supply the plant cooling water to the heat exchange pipe when not supplying steam from the , A steam water separator pressure detector for detecting the steam pressure in the steam water separator, and a steam pressure detected by the steam water separator pressure detector when the steam from the steam water separator is not supplied to the steam utilization facility Is controlled so as to be maintained at a predetermined value by controlling the plant cooling control valve to control the flow rate of the plant cooling water supplied to the heat exchange pipe. 3. A fuel cell main body that generates electric energy from a fuel and an oxidant and cools reaction heat at that time with cooling water, and brackish water that separates waste cooling water that has cooled the fuel cell main body into water and steam. A separator, a steam utilization facility that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator, and the water separated by the brackish water separator is used as cooling water for the fuel cell body. In the fuel cell power generation plant, the heat exchange pipe for exchanging heat with the plant cooling water from the plant cooling system, which is provided in the brackish water separator, and the brackish water separator in the steam utilization facility. And a plant cooling control valve for controlling the amount of the plant cooling water while switching to supply the plant cooling water to the heat exchange pipe when not supplying steam from the The exhaust cooling water temperature detector for detecting the exhaust cooling water temperature at the outlet of the fuel cell body, and the exhaust cooling water temperature detector when the steam from the steam separator is not supplied to the steam utilization facility A fuel comprising: a controller for controlling the flow rate of the plant cooling water supplied to the heat exchange pipe by adjusting the plant cooling control valve so that the temperature of the exhaust cooling water is maintained at a predetermined value. Battery power plant. 4. A fuel cell main body that generates electric energy from a fuel and an oxidant and cools reaction heat at that time with cooling water, and brackish water that separates waste cooling water that has cooled the fuel cell main body into water and steam. A separator, a steam utilization facility that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator, and the water separated by the brackish water separator is used as cooling water for the fuel cell body. In the fuel cell power generation plant, the heat exchange pipe for exchanging heat with the plant cooling water from the plant cooling system, which is provided in the brackish water separator, and the brackish water separator in the steam utilization facility. And a plant cooling control valve for controlling the amount of the plant cooling water while switching to supply the plant cooling water to the heat exchange pipe when not supplying steam from the The exhaust cooling water pressure detector for detecting the exhaust cooling water pressure at the outlet of the fuel cell body, and the exhaust cooling water pressure detector when the steam from the steam separator is not supplied to the steam utilization facility A fuel comprising: a controller for controlling the flow rate of the plant cooling water supplied to the heat exchange pipe by adjusting the plant cooling control valve so that the exhaust cooling water pressure is maintained at a predetermined value. Battery power plant. 5. A fuel cell main body that generates electric energy from a fuel and an oxidant and cools reaction heat at that time with cooling water, and brackish water that separates waste cooling water that has cooled the fuel cell main body into water and steam. A separator, a steam utilization facility that uses steam from the brackish water separator, and a plant cooling system that cools the brackish water separator, and the water separated by the brackish water separator is used as cooling water for the fuel cell body. In the fuel cell power generation plant, the heat exchange pipe for exchanging heat with the plant cooling water from the plant cooling system, which is provided in the brackish water separator, and the brackish water separator in the steam utilization facility. And a plant cooling control valve for controlling the amount of the plant cooling water while switching to supply the plant cooling water to the heat exchange pipe when not supplying steam from the A battery current detector that detects a battery current that is the output of the fuel cell main body, and based on the battery current detected by the battery current detector when the steam from the steam separator is not supplied to the steam utilization facility And a controller for controlling the flow rate of the plant cooling water supplied to the heat exchange pipe by adjusting the plant cooling control valve so that the cooling water temperature in the brackish water separator is maintained at a predetermined value. A fuel cell power plant characterized by the above. 6. A fuel cell main body for generating power by an electrochemical reaction between a fuel and an oxidant, a cooling water circulation pump for supplying cooling water for cooling the fuel cell main body to the fuel cell main body, and cooling the fuel cell main body. A steam separator for separating the waste cooling water into water and steam, and a heat exchange pipe arranged in the steam separator for exchanging heat with the water in the steam separator to cool the water. A fuel cell power plant characterized by the above. 7. A steam utilization facility that uses steam from the steam separator, and the steam separation by heat exchange through the heat exchange pipe when steam from the steam separator is not supplied to the steam utilization facility. The fuel cell power generation plant according to claim 6, further comprising a plant cooling water control valve that cools water in the reactor. 8. A control for controlling an amount of heat exchange by the heat exchange pipe so that a predetermined process state amount maintains a predetermined set value when the steam from the steam separator is not supplied to the steam utilization facility. The fuel cell power plant according to claim 6 or 7, further comprising a device.