JPH06283184A - Fuel cell indirect steam extracting type steam separator of fuel cell power generation system - Google Patents

Abstract

PURPOSE:To maintain a function of condensation and recovery by feeding superheated steam to a secondary steam generation system while condensing superfluous steam in a cooling water system, and by keeping the amount of steam at a favorable level. CONSTITUTION:A steam generator inlet control valve 23 is provided on a piping line that connects a steam separator 30 with a steam generator 30. The control valve 23 and the generator 3 are bypassed and cooling water 2b is made to flow in a circulation pump 4 by a bypass line 22. The water of a secondary steam generation system is heated by cell cooling water and steam is formed in the generator 3, and saturated steam flows into a heat exchanger group 32 provided on the part of the steam 2a of the separator 30. The saturated steam is further heated and superheated steam is thus formed. The outer surface of the heat exchanger group 32 is formed into two- phase flow in the cooler of a cell main body, condensing the superfluous steam of the cooling water system while maintaining the amount of steam formed by the separator 30 at a favorable level. After the superheated steam is utilized by a steam waste heat utilization device it, it becomes condensed water and is returned to the generator 3 by a make-up water pump 17. The function of condensing and recovering cooling water is thus maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generation system, and more particularly to a steam and hot water supply system utilizing waste heat, and an indirect steam extraction type steam separator associated therewith.

[0002]

2. Description of the Related Art A fuel cell power generation system converts chemical energy of fuel such as city gas or propane gas into electric energy, and is an apparatus for producing hydrogen from a fuel cell main body and fuel such as city gas or propane gas. , A converter for converting a direct current generated in the fuel cell main body into an alternating current, a heat exchanger for maintaining the temperature of the working gas at a temperature suitable for the operation of the fuel cell main body and hydrogen generation, and the like. The fuel cell main body directly converts the binding energy between hydrogen gas generated by hydrogen generation and oxygen in the air into electric energy, but at the same time, heat is also generated.

As described above, the fuel cell power generation system is evaluated as a clean power generation system having high power generation efficiency, low emission of air pollutants, and low noise due to power generation by a chemical reaction.

By the way, in order to efficiently carry out the electrochemical reaction of the fuel cell body, it is necessary to keep the temperature of the fuel cell body at a constant temperature level.
It is cooled to an appropriate temperature. Therefore, the cooling water system of the fuel cell power generation system is composed of a steam separator, a pump, a heat exchanger, etc., and exhaust heat taken out from the heat exchanger is used for various purposes. This exhaust heat is generally taken out as hot water, but in recent years, there has been a strong demand for taking out steam in order to expand the range of uses of the exhaust heat.

FIG. 7 is a characteristic diagram showing a relationship between general power generation load and total thermal efficiency of a fuel cell power generation system. As can be seen from this characteristic diagram, the power generation efficiency for the power generation load is
Although it is 40%, the total thermal efficiency is 80% or more when all of the low temperature exhaust heat recovery component at the hot water level and the high temperature exhaust heat recovery component at the steam level are used. As described above, the fuel cell power generation system can effectively use not only power generation but also exhaust heat outside the system. Especially, high temperature exhaust heat of vapor level out of the exhaust heat is used as a drive source of the absorption chiller, steam. It is highly useful as a drive source for turbines.

8 and 9 heat the water of the secondary steam generating system separated from the battery cooling water system to generate steam from the surplus heat of the battery cooling water adopting the conventional exhaust heat utilization system. 1 shows an example of the configuration of a fuel cell power generation system provided with a steam generator. Various proposals have already been made regarding a method of supplying steam generated from the steam generator to an exhaust heat utilization device and a method of coping with diversification of exhaust heat utilization using the steam generator.

As shown in FIGS. 8 and 9, the fuel electrode 1
a, the reaction heat generated in the fuel cell main body 1 including the air electrode 1b and the cell cooler 1c is taken out by exchanging heat with the cell cooling water in the cell cooler 1c. It becomes a liquid two-phase flow and is introduced into the steam separator 2. In the steam / water separator 2, the steam 2a of the gas-liquid two-phase flow is separated and liquefied into a battery cooling water 2b, and in the steam generator 3 provided downstream of the steam / water separator 2, the battery cooling water 2b is discharged. The water in the secondary steam generation system separated from the battery cooling water system is heated from the excess heat of to generate steam, and the battery cooling water 2b whose temperature is lowered by this is generated in the battery cooling water circulation pump 4
Thus, the battery cooling water system is configured to be guided to the battery cooler 1c through the temperature adjusting heat exchanger 5 and the battery cooling water heating electric heater 6.

On the other hand, the steam 2a separated by the steam separator 2a
Is supplied to the fuel reforming steam superheater 21 and is heated by the fuel reforming steam superheater 21 to become superheated steam. This superheated steam is mixed with fuel at a certain ratio and the catalyst in the fuel reformer 7 is heated. The hydrogen-rich gas is converted by the endothermic reaction of passing through the layer and being heated by the burner combustion gas in the fuel reformer 7 during this period.

In the case of the structure shown in FIG. 8, the burner combustion exhaust gas burned in the fuel reformer 7 is discharged from the fuel reformer 7, and then the heating source of the burner air preheater 8 of the fuel reformer 7. As a result, the heat is exchanged with the air, and after that, it merges with the exhaust air in the fuel cell main body 1 and flows into the integrated exhaust gas treatment device 9. The integrated exhaust gas treatment device 9 has a phosphoric acid removing function of removing and recovering phosphoric acid from exhaust gas containing a phosphoric acid solution which is diffused from the electrolyte of the fuel cell main body 1 and is discharged together with the generated steam, and a phosphoric acid removing function included in the exhaust gas. It has a condensed water recovery function that condenses and recovers the generated water vapor that is generated, and proposals regarding its function and configuration have already been made.

The saturated steam generated on the secondary side of the steam generator 3 is supplied to the secondary steam generating system of the steam exhaust heat utilization device 11 through the steam supply line 3e and used, and then the condensed water is condensed. And is returned to the lower side (liquid phase side) of the steam generator 3 through the condensed water return pipe 3d by the steam generator makeup water pump 17. The condensed water in the exhaust gas generated and collected on the primary side of the integrated exhaust gas treatment device 9 is introduced into the water treatment device 16 through the condensed water recovery line 19, and the cooling water treated here is steam-water separator. It is configured to return to the downstream side of 2.

In the figure, 3a is secondary steam, 3b is high temperature water, 3c is a steam generator blow line, 10 is blowdown water heat exchanger, 13 is hot water exhaust heat recovery heat exchanger, and 15 is secondary. Secondary cooling water cooler, 18 make-up water supply line, 19 condensate recovery water line, 20 blowdown water line, 22 steam generator bypass line, 23 steam generator inlet control valve, 24 steam generator bypass The control valve is shown.

In the case of the configuration shown in FIG. 9, the saturated steam generated on the secondary side of the steam generator 3 is used in the secondary steam superheater 25 which uses the combustion exhaust gas discharged from the fuel reformer 7 as a heating source. By further heating, the superheated steam is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11 via the steam supply line 3e, and high-quality superheated steam is supplied to the exhaust heat utilization device.

[0013]

However, in the conventional fuel cell power generation system which employs such a steam exhaust heat utilization device, it is extracted from the cell cooler 1c of the fuel cell body 1 as a gas-liquid two-phase flow. There is no function of condensing and recovering excess vapor of the required amount of supply to the fuel reformer 7 in the vapor phase of the cell cooling water, and the temperature of the cell cooling water system is maintained at an appropriate temperature for the fuel cell main body 1. There was a problem that it was difficult to do.

Here, in order to improve the operating performance of the fuel cell main body 1, for example, in order to improve the operation performance of the fuel cell main body 1, it is necessary to prevent the excess steam content exceeding the required supply amount to the fuel reformer 7 from occurring in the steam separator 2. When the amount of cooling water is reduced to increase the gas-liquid two-phase flow region at a certain saturation temperature so that the temperature distribution of the cell cooler 1c inside the fuel cell body 1 becomes uniform, the gas phase at the outlet of the cell cooler 1c is increased. It is possible that the ratio of minutes will increase.

On the other hand, on the other hand, as high temperature exhaust heat, superheated steam having a high utility value as a drive source of an absorption chiller, a drive source of a steam turbine, etc. is generated, and the superheated steam is generated in a secondary steam generation system. Demand is increasing, but Fig. 9
As shown in, in the method of heating the saturated steam generated on the secondary side of the steam generator 3 with the exhaust gas of the fuel reformer 7 to turn it into superheated steam, the secondary steam superheater 25 uses gas-steam heat exchange. Since it is a heat exchanger, the required heat transfer area is large and the heat exchanger has a large volume, which causes a problem in downsizing the plant.

Further, in such a conventional fuel cell power generation system, when the secondary steam generation system of the steam exhaust heat utilization apparatus takes a long time to start or the cooling water temperature of the fuel cell body 1 is low, The generated steam temperature of the battery cooling water system and the secondary steam generation system of the exhaust heat utilization device becomes low, the desired secondary steam temperature cannot be obtained, and the operation efficiency of, for example, an absorption chiller on the exhaust heat utilization device side decreases. However, there are problems such as matching of operating temperatures between the fuel cell power generation system side and the exhaust heat utilization device side, and simultaneous operation temperature control between the fuel cell power generation system side and the exhaust heat utilization device side becoming difficult.

Therefore, in order to solve the above problems, the object of the present invention is to generate secondary steam by further heating the secondary saturated steam generated in the steam generator with the surplus heat in the steam separator. A fuel cell for a fuel cell power generation system that is capable of supplying the desired superheated steam necessary for the system and also has a function of condensing and recovering excess steam that is more than the necessary supply amount to the fuel reformer of the cell cooling water system. It is to provide an indirect steam extraction type steam separator.

[0018]

In order to achieve the above object, the present invention provides a fuel cell main body having a fuel electrode, an air electrode, and a cooler, and a hydrogen gas produced by reforming the fuel. A fuel reformer that supplies the fuel electrode of the cell body, a steam separator that separates the two-phase flow cooling water that is heated by the reaction heat of the fuel cell into a gas phase and a water phase, and this steam separator The cooling water circulation pump that circulates the cooling water separated in step 1 through the cooler of the fuel cell main body and the state in which it is separated from the fuel cell cooling water system by the excess heat of the cell cooling water system on the downstream side of the water phase outlet of the steam separator. The secondary saturation generated in the steam generator in the fuel cell indirect steam extraction type water-water separator of the fuel cell power generation system that consists of a steam generator that supplies steam to the secondary steam generation system of the exhaust heat utilization device Steam flows into the heat transfer tube inside And further heat to generate superheated steam, which is supplied to the secondary steam generation system, and the excess steam of the battery cooling water system is condensed on the outer surface of the heat transfer tube to generate a desired amount of steam. The feature is that the function of maintaining the value is retained.

[0019]

With the above-mentioned structure, the excess steam of the battery cooling water system can be condensed and the amount of water vapor generated in the steam separator can be maintained at a desired value, and the maximum heat capacity in the system can be maintained. It is possible to supply superheated steam to the secondary steam generation system of the indirect exhaust heat utilization device in a state where it is separated from the fuel cell cooling water system from inside the large steam separator and to increase the indirect superheated steam extraction amount, The efficiency of exhaust heat recovery from the system can be improved.

As a result, the heat exchanger relating to the indirect steam extraction of the secondary steam generation system, which was conventionally installed alone in the fuel cell cooling water system, that is, the steam generator, the steam superheater, or the exhaust heat recovery preheater is used. Since it can be incorporated in a steam separator, the plant equipment can be made compact and economically advantageous.

Further, it is possible to integrate a steam / water separator incorporating a heat exchanger for taking out the indirect steam of the secondary steam generation system and the secondary steam / water separation drum. This also makes it possible to make the plant equipment compact and is economically advantageous.

Further, by providing a heating heater in the steam / water separator integrated with the indirect steam extraction function, the fuel cell cooling water system and the secondary steam generation system of the exhaust heat utilization device at the time of starting the fuel cell power generation system are provided. It is possible to simultaneously increase the temperature of the fuel cell power generation system, and to facilitate simultaneous operation control of the fuel cell cooling water and the secondary steam generation system of the exhaust heat utilization device during operation of the fuel cell power generation system.
When the generated steam temperature of the secondary steam generation system of the exhaust heat utilization device is low, the primary side (high temperature side, that is, battery cooling water side) or the secondary side (low temperature side, that is, steam generation side) in the steam generator It is also possible to operate the heater installed in (1) to obtain a desired secondary steam temperature, and efficient operation that matches the exhaust heat utilization device of the fuel cell power generation system becomes possible.

Further, this makes it possible to combine the heating heater, which has conventionally been installed alone in the fuel cell cooling water system, with the steam separator and the steam generator, and to make the plant equipment compact and economical. Will also be advantageous.

Further, hot water is supplied to the exhaust heat utilization device on the downstream side of the secondary steam / water separation drum or the integrated steam / water separator and the secondary steam / water separation drum side of the secondary steam / water separation drum. Excess saturated water (high temperature water) other than the steam amount by connecting the system
By taking out the high temperature water, the high temperature water can be supplied also to the exhaust heat utilization device that requires the high temperature water, and it is possible to cope with the diversification of utilization of the exhaust heat.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts as those in FIG. 8 and FIG. 9 will be assigned the same reference numerals and overlapping description will be omitted.
FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 30 is a steam separator, which is installed on the upstream side of the steam generator 3 and is a saturated steam 3a generated on the secondary side of the steam generator 3.
Is superheated steam, and this superheated steam is supplied to the secondary steam generation system of the exhaust heat utilization device 11.

That is, in the steam-water separator 30, the heat transfer tube group 32 for heating the saturated steam generated on the secondary side of the steam generator 3 is arranged in the gas phase 2a portion of the container 31, and the liquid phase 2b is arranged in the lower part. A water phase outlet downcomer 33 communicating with the heat transfer tube group 32
At the inlet side of the steam generator 3 through a saturated steam supply pipe 34
The secondary generated steam 3a portion is connected, and the steam exhaust heat utilization device 11 is connected to the outlet side of the heat transfer tube group 32 via the secondary steam supply line 3e. The state in which the battery cooling water introduced from the battery cooler is separated into the gas phase (steam) 2a in the upper half part and the liquid phase (cooling water) 2b in the lower half part in the container 31 is shown in FIG. It goes without saying that various arrangements, arrangements, shapes, types, etc. of the 32 can be appropriately selected depending on the design method.

Next, the overall fuel cell power generation system in which the steam / water separator 30 having the above-described configuration is installed will be described.
First, the two-phase flow of the cell cooling water in the cell cooler 1c of the fuel cell body 1 flows into the steam separator 30 through the cell cooling water inlet nozzle 35, and the gas phase (hereinafter referred to as steam) 2a and a liquid phase (hereinafter referred to as cooling water) 2b are separated. The separated cooling water 2b flows out through the water phase outlet downcomer 33 of the steam separator 30 by the battery cooling water circulation pump 4 and flows through the primary side (high temperature side) of the steam generator 3 installed downstream thereof. , The water on the secondary side (steam generation side) of the steam generator 3 is heated to make it saturated steam. The battery cooling water on the primary side (high temperature side) that has been heat-exchanged and cooled by heating the water on the secondary side (steam generating side) in the steam generator 3 passes through the battery cooling water circulation pump 4 as shown in FIG. The cell cooling water system is configured so as to be returned to the cell cooler 1c of the fuel cell main body 1 again after being introduced into the temperature adjusting heat exchanger 5 and subjected to temperature adjustment.

In this case, a steam generator inlet control valve 23 is provided in the pipe line connecting the steam separator 30 and the steam generator 3, and the steam generator inlet control valve 23 and the steam generator are also provided. Bypass line 22 for bypassing 3 to flow cooling water 2b from steam separator 30 to battery cooling water circulation pump 4
Is installed in the steam generator bypass line 22.
Is provided with a steam generator bypass control valve 24.

Here, the steam generator 3 heats the water of the secondary steam generating system by the battery cooling water flowing to the primary side to generate steam, and the primary side inlet header part and the primary side outlet header part are As shown in FIG. 1, the heat transfer tube groups 3g are connected. Saturated steam 3 generated on the secondary side of this steam generator 3
a is a container of the steam separator 30 through the saturated steam supply pipe 34.
The superheated steam is generated by flowing into the heat transfer tube group 32 arranged in the upper steam 2a portion in 31 and further heating by the heat of the steam 2a portion in the steam separator 30, and the secondary steam supply line It is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11 via 3e. On the other hand, the heat transfer tube group 32 condenses, on its outer surface, the surplus steam of the cell cooling water system that has been two-phase-flowed in the cell cooler 1c of the fuel cell body 1, and the amount of water vapor generated in the steam separator 30. Also has a function of maintaining a desired value.

Thus, the superheated steam supplied to the steam exhaust heat utilization device 11 via the secondary steam supply line 3e becomes condensed water after being used in the steam exhaust heat utilization device 11, and this condensed water is generated as steam. It is returned to the steam generator 3 via the steam generator water supply line 3d by the steam supply water pump 17. The surplus saturated water (high temperature water) 3b other than the steam component in the steam generator 3 is
The water is supplied to the hot water exhaust heat utilization device 12 that utilizes the hot water exhaust heat via the hot water supply pipe 3f, and at the same time, a part of the water treatment device is shown in FIG. 8 in order to ensure the water quality in the steam generator 3.
The water intermittently supplied to 16 through the steam generator blowing line 3c and treated by the water treatment device 16 is again supplied to the battery cooling water system as makeup water for the battery cooling water system through the water treatment makeup water supply line. Introduced (see FIG. 8). Here, FIG.
The position where the water treated by the warm water exhaust heat utilization device 12 is returned to the battery cooling water system is in front of the battery cooling water circulation pump 4, but it is not limited to this position depending on how the system is assembled. Needless to say.

Incidentally, 36 in FIG. 1 is a secondary steam supply line 3e.
A pressure detector that detects the steam pressure of the superheated steam installed in 37, 37 is the opening degree of the secondary steam pressure control valve 38 so as to keep the pressure for supplying this superheated steam to the steam exhaust heat utilization device 11 to a predetermined value. It is a pressure controller to adjust.

Next, the operation of the embodiment of the present invention constructed as described above will be described. First, the case where the temperature of the cooling water of the cell cooling water system is raised when the fuel cell power generation system is started will be described. First, the battery cooling water circulation pump 4 is activated to circulate the cooling water in the battery cooling water system, and at the same time, the battery cooling water heating electric heater 6 installed in the battery cooling water system is activated to set the temperature of the battery cooling water system to a predetermined value. To raise the temperature. At this time, the steam generator bypass control valve 24 is opened and the steam generator inlet control valve 23 is closed in order to efficiently raise the temperature of the cooling water in the battery cooling water system. However, in the case of simultaneously raising the temperature of the battery cooling water system and the secondary steam generation system, the bypass control valve 24 is closed and the steam generator inlet control valve 23 is opened, and the steam generator 3 is activated from the start of the system. An operation in which the secondary side (steam generation side) is heated from the primary side (battery cooling water side) is also conceivable. When the temperature of the secondary side of the steam generator 3 is still low at the time of starting the system and it is not necessary to generate the secondary steam, the opening degree of the secondary steam pressure control valve 32 is adjusted to adjust the opening of the steam generator 3. Set the pressure on the secondary side lower than the pressure on the primary side (battery cooling water side).

However, when the temperature on the primary side (battery cooling water side) reaches the specified temperature and the system operation starts and the steam exhaust heat utilization device 11 is operated, the secondary steam pressure control valve
By adjusting the opening degree of 32, the steam of the prescribed steam pressure is generated from the secondary side of the steam generator 3, and this steam is stored in the container of the steam separator 30.
It is made to flow into the heat transfer tube group 32 installed in the upper steam 2a portion in 31 and is further heated by the heat of the steam 2a portion in the steam separator 30 to generate superheated steam, and the secondary steam supply line 3e To the secondary steam generation system of the steam exhaust heat utilization device 11.

Here, for example, the steam 2 in the steam separator 30
a, the temperature of the cooling water 2b is 185 ° C, and even if it flows into the primary side of the steam generator 3 at a temperature of 185 ° C under ideal conditions, the temperature of the secondary side of the steam generator 3 is Due to design restrictions of 3 (for example, the steam generator 3 cannot be increased in size by unnecessarily increasing the heat transfer area due to the relationship between the pinch temperature of the heat exchanger and the heat transfer area).
It is only possible to take out steam as saturated steam at ~ 170 ° C, and it is difficult to take out steam as superheated steam.

However, the heat transfer tube group in the steam separator 30
It is possible to generate superheated steam by injecting this saturated steam into 32 and further heating it with the heat of the steam 2a portion, and depending on the operating temperature in the steam separator 30, the steam inside the steam separator 30 170 to 184 ° C, slightly below the temperature
It becomes possible to generate superheated steam of.

On the other hand, since the excess steam of the cell cooling water system can be condensed outside the heat transfer tube group 32 in the steam separator 30, the amount of this excess steam is used as the cell cooler 1c of the fuel cell body 1. By adjusting the two-phase flow ratio of the cell cooling water that comes out from the cell cooling water amount or the battery bypass water amount that bypasses the fuel-fuel cell main body 1 or the like, it is possible to change the load of the amount of superheated steam supplied to the steam exhaust heat utilization device 11. Can respond.

Here, when it is not necessary to supply steam or hot water on the exhaust heat utilization device 11 or 12 side, the steam generator bypass control valve 24 is opened and the steam generator inlet control valve 23 is closed. , The two-phase flow ratio of the cell cooling water discharged from the cell cooler 1c of the fuel cell body 1 to
By adjusting the amount of battery bypass water that bypasses the battery, etc., operation is performed under conditions that do not generate excess steam in the battery cooling water system.

As described above, in the above-described embodiment (hereinafter referred to as the first embodiment), the steam generator 3 is installed on the downstream side of the water phase outlet of the steam separator 30, and the steam generator 3 is connected to the steam generator 3. Not only is the water on the secondary steam generation side heated by the excess heat of the battery cooling water to generate saturated steam 3a, but the secondary saturated steam generated on the secondary side (steam generation side) of the steam generator 3 is separated into steam and water. Flows into the heat transfer tube group 32 disposed in the upper steam 2a portion of the container 30, and further heats to generate superheated steam, and supplies the superheated steam to the secondary steam generation system. The steam-water separator 30 is provided with a function of condensing excess steam of the battery cooling water system on the outer surface of 32 and maintaining the amount of water vapor generated in the steam-water separator 30 at a desired value. The amount of water vapor generated in 30 can be maintained at a desired value, and The indirectly capable of supplying superheated steam to a secondary steam generating system of the steam exhaust heat utilization device 11 in the most heat capacity larger steam separator state of being separated from the fuel cell cooling water system from the inside 30 of the. In addition, this makes it possible to increase the amount of indirect superheated steam taken out, generate superheated steam with high utility value as steam exhaust heat, and supply it to the secondary steam generation system, and recover high-temperature exhaust heat from the system. The efficiency can be further increased.

Further, a heat transfer tube group as a secondary steam superheater
It becomes possible to incorporate 32 into the steam separator 30, which makes the plant equipment compact and is economically advantageous.

Next, another embodiment of the present invention (hereinafter referred to as a second embodiment) will be described. The same parts as those in FIG. 1 are designated by the same reference numerals, and duplicated description will be omitted. FIG. 2 is a configuration diagram showing a second embodiment of the present invention. In the figure, 40 is a steam separator, which is installed on the upstream side of the steam generator 3 in the same manner as in the first embodiment described above, and the saturated steam 3a generated on the secondary side of the steam generator 3 is steamed. The separator 40 is configured so as to rise vertically and is further heated to become superheated steam, and the superheated steam is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11.

That is, in the steam separator 40, the heat transfer tube group 42 penetrating in the vertical direction is arranged in the container 41, and the water phase outlet downcomer 33 is provided in the lower portion at a position different from the heat transfer tube group 42. The secondary generated steam 3a portion of the steam generator 3 is connected to the inlet side of the heat transfer tube group 42 through the saturated steam supply pipe 44, and the secondary steam supply line 3e is connected to the outlet side of the heat transfer tube group 42. The steam exhaust heat utilization device 11 is connected via the. In the container 41, the battery cooling water introduced from the battery cooler is separated into the steam 2a in the upper half and the cooling water 2b in the lower half, the arrangement of the heat transfer tube group 42, and the tube arrangement. It goes without saying that various shapes, shapes, types, etc. can be appropriately selected depending on the design method.

In the above structure, the saturated steam 3a generated on the secondary side of the steam generator 3 is vertically arranged in the container 41 of the steam separator 40 via the saturated steam supply pipe 43. It flows into the group 42 and is further heated in the heat transfer tube group 42 to generate superheated steam, and the secondary steam supply line 3
It is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11 via e.

On the other hand, the heat transfer tube group 42, on the outer surface thereof, first exchanges heat with the cooling water 2b portion of the two-phase flow of the cell cooling water system in the cell cooler 1c of the fuel cell main body 1, and then the steam. It also has a function of condensing the excess steam in the steam separator 40 by exchanging heat with the portion 2a and maintaining the amount of steam generated in the steam separator 40 at a desired value.

The second embodiment configured as described above differs from the first embodiment described above in that the heat transfer tube group in the steam separator is horizontally arranged in the container 31 in the first embodiment. On the other hand, in the second embodiment, the heat transfer tube group 42 is vertically penetrated in the container 41, so that the heat transfer tube group 42 is vertically penetrated as shown in FIG. This has the advantage that the flow form of the superheated steam flowing in the pipe can be made more stable.
Further, as a modified example of the heat transfer tube group 42, for example, it is also possible to install a plate fin type heat exchanger or the like that can achieve a compact heat exchanger, and thereby in the steam separator 40 as a secondary steam superheater. It becomes possible to incorporate it. Other operations and operations are similar to those of the first embodiment, and the same effects as the first embodiment can be obtained.

Next, still another embodiment of the present invention (hereinafter referred to as a third embodiment) will be described. The same parts as those in FIG. 1 are designated by the same reference numerals, and duplicated description will be omitted.
FIG. 3 is a configuration diagram showing a third embodiment of the present invention. In the figure, 50 is a steam separator, which is different from the first and second embodiments described above, and instead of the steam generator in the downstream, the secondary heat is almost transferred to the secondary steam generation system by the excess heat of the battery cooling water system. A preheater 53 that preheats to the temperature range of saturated water is installed, and the saturated water generated on the secondary side of this preheater 53 is arranged in the steam separator 50 through the saturated steam supply pipe. The secondary steam is heated to become superheated steam or saturated steam, and is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11.

In order to deal with the case where the generated secondary steam is saturated steam, a secondary steam / water separation drum 55 for separating the secondary saturated steam into a gas phase and a liquid phase is installed to discharge the steam. The secondary steam generation system of the heat utilization device 11 can be supplied as saturated steam with no wetness so that the secondary steam recovered as exhaust heat can handle either case of superheated steam or saturated steam. It is configured in.

That is, the steam separator 50 is the gas phase of the container 51.
A heat transfer tube group 52 is arranged in the 26 part, and a water phase outlet downcomer 33 is provided in the lower part. Water phase outlet downcomer 33, preheater 53
Connect to. The inlet side of the heat transfer tube group 52 is connected to the secondary side of the preheater 53 via the hot water supply line 54, and the outlet side of the heat transfer tube group 52 is connected to the secondary steam / water separation drum via the secondary steam supply line 3e. Connected to 55. The secondary steam / water separation drum 55 is provided with a drum level detector 56, and the makeup water supply line 18
The secondary saturated water flow rate control valve 57 provided in the pipe connected to is adjusted. Further, in the secondary steam / water separation drum 55, the steam pressure detector 36 is connected to the gas phase 55a, and the liquid phase 55b is used for the hot water exhaust heat utilization device 12 and the drum blow through the secondary saturated water hot water supply pipe 58. Each is connected to a water treatment device (not shown) via a line 59.

The third embodiment constructed as described above is different from the first embodiment in that the preheater 53 is provided downstream instead of the steam generator.
By installing the preheater 53, secondary steam cannot be taken out only by the preheater 53 unlike the steam generator, but since the preheater 53 is generally a water-water heat exchanger having a high coefficient of heat transmission, the preheater 53 The feature is that the volume of 53 can be made considerably smaller than the volume of the steam generator, and there is an advantage that the total plant volume including the steam separator can be made compact.

Next, the operation of the steam / water separator 50 of the third embodiment configured as described above will be described with respect to the secondary steam generating system different from the first embodiment described above. Steam waste heat utilization device 11
Make-up water such as condensed water after being used in the secondary steam generating system is supplied by the steam generator make-up water pump 17 to the steam generator water supply line 3
It is returned via d and is supplied to the secondary side (low temperature side) of the preheater 53, where the makeup water is preheated to a temperature range of almost saturated water, and the hot water supply line 54 is used to supply the water inside the steam separator 50. Is further heated by flowing through the heat transfer tube group 52 arranged in
It becomes superheated steam or saturated steam and is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11.

Here, by restricting the flow rate of hot water flowing into the preheater 53 of the secondary steam generation system, the steam exhaust heat utilization device 11
It is possible to supply the prescribed superheated steam to the above, and in that case, the secondary steam steam separation drum 55 as shown in the same figure is not required. However, in actual operation, there are fluctuations in the amount of excess steam in the battery cooling water system due to load fluctuations in the plant, fluctuations in the flow of the secondary steam generation system, etc., and with the configuration of the third embodiment, the secondary steam / water separation drum 55 By installing, it becomes possible to operate the plant stably.

Further, when the superheated steam can be taken out as the secondary steam, the superheated steam is supplied from the upper nozzle of the secondary steam steam separation drum 55 to the secondary steam generation system of the steam exhaust heat utilization device 11. Is supplied to.

On the other hand, under the condition that the saturated steam can be taken out, the saturated steam 2a generated in the steam separator 50 is steam (gas phase) 55a and saturated water (liquid) in the secondary steam steam separation drum 55. Phase) 55b, and only saturated steam is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11 from the upper nozzle of the secondary steam steam separation drum 55.

Further, when the surplus saturated water 55b other than the steam component in the secondary steam / water separation drum 55 is supplied to the hot water exhaust heat utilization device 12 for utilizing the hot water exhaust heat via the hot water supply pipe 58. At the same time, in order to secure the water quality in the secondary steam / water separation drum 55, a part of it is intermittently supplied to the water treatment device 16 through a drum blow line 59 and is treated by this water treatment device 16. The water is reintroduced into the battery cooling water system as makeup water for the battery cooling water system through the water treatment makeup water supply line.
The water level in the secondary steam / water separation drum 55 is detected via the drum level detector 56, and the opening degree of the saturated water flow rate control valve 57 downstream of the secondary steam / water separation drum is thereby adjusted. .

The other operation and operation of the steam separator are the same as those of the first embodiment described above, and the same effects as the first embodiment can be obtained in the third embodiment. Next, still another embodiment of the present invention (hereinafter, referred to as a fourth embodiment) will be described. The same parts as those in FIG. 1 are designated by the same reference numerals, and duplicated description will be omitted.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In the figure, 60 is a steam separator, and downstream of this steam separator 60, instead of the steam generator as in the third embodiment, the secondary steam generation system is generated by the excess heat of the battery cooling water system. A preheater 53 for preheating to a temperature range of almost saturated water is installed, and saturated water generated on the secondary side of the preheater 53 is caused to flow into the heat transfer tube group arranged in the steam separator 60. By further heating, the secondary steam is made into superheated steam or saturated steam, and this is supplied to the secondary steam generation system of the steam exhaust heat utilization apparatus 11, but in the third embodiment described above. The secondary steam steam separation drum 55 and the steam separator 50 for separating the secondary saturated steam into a gas phase and a liquid phase are integrated,
It is characterized by being compact.

That is, in the steam / water separator 60, the container 61 is divided into a steam / water separator 62 and a secondary steam / water separator 63 by a partition plate 61a. Thus, in the steam separation unit 62, the heat transfer tube group 64 is disposed in the steam 2a portion, and the water phase outlet downcomer 33 is disposed in the lower portion. The water phase outlet downcomer 33 is connected to the preheater 53. The inlet side of the heat transfer tube group 64 is connected to the secondary side of the preheater 53 via the hot water supply line 54, and the outlet side of the heat transfer tube group 64 is connected to the secondary steam / water separation section 63. Further, the cooling water 2b in the steam / water separator 62 in the integrated steam / water separator 60 is
And the liquid phase 53b in the secondary steam / water separation unit 63 are provided with independent heaters 65a and 65b, respectively. Electricity, steam, hot water or the like is appropriately selected and used as a heat source of the heaters 65a and 65b.

In this case, the heating heaters for heating the fuel cell cooling water system and the secondary steam generating system of the exhaust heat utilization device are the lower part and the secondary side of the fuel cell cooling water system secondary side (steam generating side) of the steam separator 60. A battery cooling water system heating heater 65a and a secondary steam generation system heating heater 65b are installed below the secondary steam steam separation unit 63 of the secondary steam generation system, respectively. It is configured to be able to heat the steam generation system.

Here, the makeup water such as condensed water after being used in the steam exhaust heat utilization device 11 to the secondary steam generation system is returned by the steam generator makeup water pump 17 through the steam generator feed water line 3d. The hot water supplied to the secondary side (low temperature side) of the preheater 53 is preheated to a temperature range of almost saturated water, and the hot water supply line
It is further heated by flowing through the heat transfer tube group 64 arranged in the steam / water separator 62 via 54 to become superheated steam or saturated steam, which flows into the secondary steam / water separator 63, where it is wet. After the amount is removed, it is supplied to the secondary steam generation system of the steam exhaust heat utilization device 11. The operation of the secondary steam / water separation section 63 is the same as that of the secondary steam / water separation drum 55 in the third embodiment described above.

Next, the operation of the fourth embodiment constructed as described above will be explained. First, the case where the temperature of the cooling water of the cell cooling water system is raised when the fuel cell power generation system is started will be described. In this case, first, the battery cooling water circulation pump 4 is activated to circulate the cooling water of the battery cooling water system, and at the same time, the battery cooling water system heater 65a installed in the lower portion of the steam separator 60 is activated to cool the battery cooling system. Heating the water temperature.

At this time, the secondary steam generating system heater 65b
Also, the simultaneous operation control with the fuel cell power generation system can be performed by activating the cell cooling water temperature in accordance with the temperature rising characteristic of reaching the specified temperature.

Here, when it is not necessary to supply steam or hot water on the side of the exhaust heat utilization device (11 or 12) and the battery cooling water temperature is also higher than the specified temperature, the heater 65 is used.
Stop the operation of a. However, depending on the operating state of the battery cooling water side, when it is necessary to heat the battery cooling water system, the battery cooling water system heater 65a may be sequentially turned on and off, and may be controlled according to the operating characteristics of the plant. The volume of the preheater 53 is also small, and the bypass control valve 24, the inlet control valve 23 and the like as shown in the first and second embodiments described above are not necessary.

On the contrary, when only the exhaust heat utilization device (11 or 12) side is activated, the battery cooling water circulation pump 4 is stopped and the secondary steam generation system heater 65a is activated to operate only the secondary steam. Can also be generated.

During operation of the fuel cell power generation system, the reaction heat generated in the fuel cell main body 1 is taken out by exchanging heat with the cell cooling water in the cell cooler 1c, and the cell cooling water is converted into a gas-liquid two-phase flow. Is introduced into the steam separator 60 and steam 2a
And the cooling water 2b, and the cooling water 2b separated by the steam / water separator 60 is the primary of the preheater 53 installed downstream of the water phase outlet of the steam / water separator 60 by the battery cooling water circulation pump 4. The cooling water introduced into the temperature adjusting heat exchanger 5 through the side (high temperature side) and further adjusted in temperature by the temperature adjusting heat exchanger 5 is returned to the battery cooler 1c.

During normal operation of the fuel cell power generation system, it is almost unnecessary to heat the battery cooling water system by the heater 6. However, when the output load of the system is lowered or the operation involving load fluctuation is performed, the battery cooling system is cooled. Due to fluctuations in the cooling water temperature of the water system, it is necessary to heat the battery cooling water system, and in such a case, the amount of steam generated in the secondary steam generating system also decreases, so Battery cooling water system heater depending on the pressure and temperature of the secondary steam generation system
65a and the secondary steam generating system heater 65b are intermittently turned on.
The N-OFF control is performed to maintain the cooling water temperature of the battery cooling water system and the pressure and temperature of the secondary steam generation system of the steam exhaust heat utilization device 11 at specified values.

When the operating load condition on the steam exhaust heat utilization device 11 side changes and the setting of the generated steam amount or the generated steam pressure supplied to the steam exhaust heat utilization device 11 side is changed, the secondary steam steam separation unit is used. The pressure is detected by the pressure detector 36 that detects the steam pressure in 63, and the pressure is changed to the set value by adjusting the opening of the pressure control valve 38, and the pressure and temperature of the generated steam are maintained at the set values. Let By controlling the operation in accordance with the operating characteristics of these systems, simultaneous operation control of the fuel cell cooling water system and the secondary steam generation system of the steam exhaust heat utilization device 11 during operation of the fuel cell power generation system can be facilitated.
The other operation and operation of the steam separator 60 are similar to those of the first embodiment described above.

In the fourth embodiment constructed as described above,
It is possible to simultaneously raise the temperature of the fuel cell cooling water system and the secondary steam generation system of the steam exhaust heat utilization device 11 when starting the fuel cell power generation system, and to generate the secondary steam of the fuel cell cooling water system and the steam exhaust heat utilization device 11. The heating time of the system can be shortened. As a result, a desired secondary steam can be supplied to the steam exhaust heat utilization device 11 side at the same time when the fuel cell power generation system starts power generation operation.

Further, during normal operation of the fuel cell power generation system, the cooling water temperature control of the cell cooling water system, the steam exhaust heat utilization device
Control of the amount of steam generated or the pressure of steam generated to be supplied to the 11 side is controlled by a battery cooling water heater installed in the steam separator 60.
65a, a secondary steam generation system heater 65b, a pressure control valve 38 of the secondary steam / water separation section 63, a level detector 56 for detecting the water level in the secondary steam / water separation section 63, and a secondary steam gas thus detected. This can be performed collectively by adjusting the opening degree of the saturated water flow rate control valve 57 downstream of the water separation drum, and can be performed simultaneously according to the load characteristics of the fuel cell cooling water system and the secondary steam generation system of the steam exhaust heat utilization device 11. Operation control can be facilitated.

Further, the surplus saturated water (high temperature water) 55b other than the steam component in the secondary steam / water separator 63 is supplied to the hot water exhaust heat utilization device 12 for utilizing the hot water exhaust heat via the hot water supply pipe 58. Since it can be supplied at the same time, it is possible to deal with diversification of exhaust heat. In addition, it is no longer necessary to install an electric heater (indicated by reference numeral 6 in FIG. 8) for heating the battery cooling water, which is conventionally installed in front of the battery cooler 1c of the fuel cell cooling water system fuel cell main body 1. Therefore, the power of the battery cooling water circulation pump 4 and the amount of heat radiation from the plant can also be reduced, which enables downsizing of plant equipment and cost reduction.

Next, still another embodiment of the present invention (hereinafter referred to as the fifth embodiment) will be described. In addition,
The same parts as those in FIG. 1 are designated by the same reference numerals, and duplicated description will be omitted. FIG. 5 is a configuration diagram showing a fifth embodiment of the present invention. In the figure, 70 is a steam separator.
Unlike the above-described fourth embodiment, the independent preheater 53 is not provided downstream of 70, and a preheating part corresponding to this preheater 53 is incorporated into the internal cooling water 2b to integrate them into a compact size. It has a feature in the point.

That is, in the steam / water separator 70, the container 71 is divided into a steam / water separator 72 and a secondary steam / water separator 73 by a partition plate 71a. In the steam-water separating unit 72, the heat transfer tube group 74 is arranged in the steam 2a portion and the heat transfer tube group 75 is arranged in the cooling water 2b portion, and the outlet side of the heat transfer tube group 75 is set to the inlet side of the heat transfer tube group 74. The heat transfer tube group 74 has an outlet side connected to the secondary steam / water separating section 73, and the heat transfer tube group 75 has an inlet side connected to the steam generator water supply line 3d. Here, the heat transfer tube group 75 has a function corresponding to that of the preheater 53 described above.

The heat transfer tube group 75 is modeled and shown as a heat transfer tube group similar to the heat transfer tube group 74 arranged in the steam 2a portion in the upper part of the steam separator 70. It goes without saying that various forms of the installation state, pipe arrangement, shape, type, etc. can be selected as appropriate depending on the design method.

The operation and operation of the fifth embodiment constructed as described above are the same as those of the third embodiment described above. According to the fifth embodiment as described above, the preheater 53 and the secondary steam superheater can be incorporated in the steam separator 70, the plant equipment can be further downsized, and it is economically advantageous. .

Next, another embodiment of the present invention (hereinafter referred to as the sixth embodiment) will be described. In addition,
The same parts as those in FIG. 1 are designated by the same reference numerals, and duplicated description will be omitted. FIG. 6 is a block diagram showing a sixth embodiment of the present invention. In the figure, 80 is a steam separator.
Reference numeral 80 denotes a configuration in which the above-described fourth embodiment and fifth embodiment are combined into one, and the steam-water separator 80 includes a heat transfer tube group of the secondary steam generation system preheater It has a configuration in which the heat transfer tube group of the secondary steam generation superheater, the secondary steam steam separation drum, the battery cooling water system heater, and the secondary steam generation system heater are all incorporated.

That is, in the steam / water separator 80, the container 81 is divided into a steam / water separator 82 and a secondary steam / water separator 83 by the partition plate 81a. In the steam-water separating unit 82, the heat transfer tube group 84 is arranged in the steam 2a portion and the heat transfer tube group 85 is arranged in the cooling water 2b portion, and the outlet side of this heat transfer tube group 85 is set to the inlet side of the heat transfer tube group 84. The heat transfer tube group 84 has its outlet side connected to the secondary steam / water separating section 83, and the heat transfer tube group 85 has its inlet side connected to the steam generator water supply line 3d. Here, the heat transfer tube group 85 has a function corresponding to that of the preheater 53 described above. Further, a battery cooling water system heater 86a is provided in the cooling water 2b of the steam separation unit 82, and a secondary steam generation system heater 86b is provided in the cooling water 55b of the secondary steam steam separation unit 83.

In the sixth embodiment as well, similar to the fifth embodiment described above, the heat transfer tube group 85 is similar to the heat transfer tube group 84 arranged in the steam 2a portion in the upper part of the steam separator. Although it is shown as a model as a heat pipe group, the installation state of the heat transfer pipe group 85 and the heat transfer pipe group 84 arranged in the steam 2a portion, the tube arrangement,
It goes without saying that various shapes, types, etc. can be appropriately selected depending on the design method.

In the sixth embodiment thus constructed, the heaters 86a and 86b and the secondary steam / water separator 83 are used.
The operation and operation of are similar to those of the above-described fourth embodiment. As described above, in the sixth embodiment, the same effect as that of the above-described fourth embodiment can be obtained, and the plant equipment can be downsized and the cost can be reduced.

In each of the embodiments described above, the image of the kettle type boiler as the steam generator 3 is shown.
Needless to say, the same exhaust heat recovery can be performed with a steam generator of another form, and the surplus saturated water (high temperature water) 3b other than the steam component in the steam generator 3 is discharged through the hot water supply pipe 3f. Although it was supplied directly to the heat utilization device 12, the secondary system pressure in the steam generator 3 may be as high as the saturated vapor pressure of the generated steam and may be pressurized hot water. In such a case, Can be dealt with by providing a pressure reducing valve in the middle of the hot water supply pipe 3f.

It is needless to say that in each of the embodiments described above, various types of systems and devices of the fuel cell power generation system related to each invention are appropriately selected.

[0079]

As described above, according to the present invention, the fuel cell main body having the fuel electrode, the air electrode and the cooler, and the hydrogen gas generated by reforming the fuel are used as the fuel electrode of the fuel cell main body. To the fuel reformer, a steam separator that separates the two-phase flow cooling water that is heated by the reaction heat of the fuel cell body into a gas phase and a water phase, and the cooling that is separated by this steam separator. Battery cooling water circulation pump that circulates water through the cooler of the fuel cell main body and exhaust heat utilization device in a state separated from the fuel cell cooling water system by excess heat of the cell cooling water system downstream of the water phase outlet of the steam separator In the fuel cell indirect steam extraction type water-water separator of the fuel cell power generation system, which is composed of a steam generator that supplies steam to the secondary steam generation system, the secondary saturated steam generated in the steam generator is Heated by flowing into the heat transfer tube provided To generate superheated steam by Rukoto,
This superheated steam is supplied to the secondary steam generation system, and at the same time, it is equipped with the function of condensing the excess steam of the battery cooling water system on the outer surface of the heat transfer tube and maintaining the generated water vapor amount at a desired value. The excess heat of the cooling water system is indirectly taken out as superheated steam with a high utility value in a state where it is separated from the battery cooling water system, and this makes it possible to improve the efficiency of exhaust heat recovery from the system, and the excess of the battery cooling water system. It is possible to provide a steam-water separator that can efficiently cope with indirect steam extraction from a fuel cell power generation system that can condense steam and maintain the amount of steam generated in the steam-water separator at a desired value.

Further, the heat exchanger relating to the indirect steam extraction of the secondary steam generation system, which is conventionally installed alone in the fuel cell cooling water system, that is, the steam generator, the steam superheater or the exhaust heat recovery preheater and the heating Since the heater can be incorporated inside the steam separator, the plant equipment can be made compact and an economically advantageous steam separator can be provided.

Furthermore, by providing a heater in the steam separator which is integrated and has an indirect steam extraction function, the fuel cell cooling water system and the secondary steam generating system of the exhaust heat utilization system at the time of starting the fuel cell power generation system are provided. Simultaneous temperature rise is possible,
Simultaneous operation control of the fuel cell cooling water and the secondary steam generation system of the exhaust heat utilization device during operation of the fuel cell power generation system can be facilitated, and an efficient match with the exhaust heat utilization device of the fuel cell power generation system can be achieved. It is possible to provide a steam separator that can be operated and can cope with diversification of utilization of exhaust heat.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing another embodiment (second embodiment) of the present invention.

FIG. 3 is a configuration diagram showing still another embodiment (third embodiment) of the present invention.

FIG. 4 is a configuration diagram showing still another embodiment (fourth embodiment) of the present invention.

FIG. 5 is a configuration diagram showing still another embodiment (fifth embodiment) of the present invention.

FIG. 6 is a configuration diagram showing still another embodiment (sixth embodiment) of the present invention.

FIG. 7 is a characteristic diagram showing the relationship between the power generation load and the total thermal efficiency of the fuel cell power generation system.

FIG. 8 is a configuration diagram showing an example of a conventional fuel cell power generation system.

FIG. 9 is a configuration diagram showing another example of a conventional fuel cell power generation system.

[Explanation of symbols]

1 ... Fuel cell main body, 1a ... Fuel electrode, 1b ... Air electrode, 1c
… Cooler, 2,30,40,50,60,70,80… Air-water separator,
3 ... Steam generator, 4 ... Battery cooling water circulating pump, 5 ... Heat exchanger for temperature adjustment, 6 ... Heater for heating battery cooling water, 7 ... Fuel reformer, 9 ... Integrated exhaust gas treatment device, 11 ... Steam exhaust Heat utilization device, 16 ... Water treatment device, 17 ... Steam generator makeup water pump, 18 ... Makeup water supply line, 31, 41, 51, 61, 71, 81 ...
Container, 32, 42, 52, 64, 74, 75, 84, 85 ... Heat transfer tube group, 33
… Water phase outlet downcomer, 36… Steam pressure detector, 37… Pressure controller, 38… Secondary steam pressure regulating valve, 53… Preheater, 55… Secondary steam steam separation drum, 56… Drum level detector, 57 ... Secondary saturated water flow rate control valve, 62, 72, 82 ... Steam / water separator, 63, 73, 83 ... Secondary steam / water separator, 65a, 65b,
86a, 86b ... Heating heater.

Claims (1)

[Claims] 1. A fuel cell main body having a fuel electrode, an air electrode and a cooler, and a fuel reformer for supplying hydrogen gas produced by reforming fuel to the fuel electrode of the fuel cell main body.
A steam separator for separating the cooling water, which is heated by the reaction heat of the fuel cell body into a two-phase flow, into a gas phase and a water phase, and the cooling water separated by the steam separator is used for the fuel cell body. A battery cooling water circulation pump that circulates through a cooler and a secondary side of an exhaust heat utilization device in a state of being separated from the fuel cell cooling water system by the excess heat of the battery cooling water system on the downstream side of the water phase outlet of the steam separator. In a fuel cell indirect steam extraction type water-water separator of a fuel cell power generation system comprising a steam generator that supplies steam to a steam generating system, the secondary saturated steam generated by the steam generator is provided inside. The superheated steam is generated by further flowing into the heat transfer tube and further heating, and supplying the superheated steam to the secondary steam generation system, and condensing the excess steam of the battery cooling water system on the outer surface of the heat transfer tube. Let it occur Fuel cell indirect vapor extraction type steam-water separator of the fuel cell power generation system is characterized in that to retain the ability to maintain the water vapor content to a desired value.