JPH0684535A - Heat output system for fuel cell - Google Patents

Abstract

PURPOSE:To reduce the water treatment burden of a water treatment equipment by preventing the condensed water, which is condensed with the steam of cooling water of two-phase flow exhausted from a fuel cell supplied to a thermal load, from mixing into the recycled water from an exhaust gas cooler which condenses the steam in the exhaust gas from a fuel cell and in the combustion exhaust gas from a fuel reformer to improve the water quality of water stored within the exhaust gas cooler. CONSTITUTION:The steam separated by a steam separator 8 is supplied to a thermal load through a steam supply systems 27, and a condensed water exhaust system 29 for discharging the condensed water condensed by a thermal load is merged with the intake side of the circulating pump 9 of a cooling water circulating systems 6, thereby preventing the condensed water from returning to an exhaust gas cooler 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention separates two-phase flow cooling water discharged by removing heat generated during power generation of a fuel cell into steam and water and supplying the steam to an external heat load. The present invention relates to a heat output system of a fuel cell, particularly a phosphoric acid fuel cell.

[0002]

2. Description of the Related Art Cooling water from which heat generated during power generation of a fuel cell, for example, a phosphoric acid fuel cell is removed, is discharged at a high temperature close to an operating temperature. In this case, since the cooling water discharged from the fuel cell is a two-phase flow composed of steam and water, the steam and water are separated, and the separated steam is supplied to an external heat load to cool the cooling water. There is known a fuel cell power generator of a combined electric and heat type that recovers exhaust heat.

The prior art will be described below with reference to the drawings. FIG. 3 is a system diagram of a portion related to a fuel cell of a conventional fuel cell power generator that supplies separated steam of cooling water to a heat load. In FIG. 3, the fuel cell 1 has an electrolyte layer (not shown) holding a phosphoric acid electrolyte, a fuel electrode 2 and an air electrode 3 sandwiching the electrolyte layer, and cooling for passing cooling water for removing heat generated during power generation. And a passage 4.

The cooling water circulation system 6 is a cooling passage 4 of the fuel cell 1.
Cooler 7 that cools the cooling water that flows through and is discharged by external cooling water, a steam separator 8 that separates the steam of the two-phase flow cooling water that is discharged from the cooler 7 from water, and a steam separator 8 It is configured by a circulation pump 9 which supplies the cooling water separated in step 1 to the cooling passage 4 of the fuel cell 1 to circulate it. The exhaust gas cooler 11 has a recovered water tank 12 that stores condensed water obtained by cooling the inflowing exhaust gas and condensing water vapor in the exhaust gas as recovered water in the lower part, and water contained in the gas released to the outside in the upper part. 13 and demister 1 for collecting
A degassing device 14 for degassing the dissolved gas in the water to be sprinkled is provided below 3.

The recovered water circulation system 16 is provided with a recovered water cooler 17 for cooling with external cooling water, and a recovered water circulation pump 18, and the recovered water tank 1 is driven by the recovered water circulation pump 18.
The water stored in 2 is made to flow between the demister 13 of the exhaust gas cooler 11 and the deaerator 14 to spray water. The recovered water supply system 20 is branched from the outlet of the recovered water cooler 17 of the recovered water circulation system 16 and is provided with a water treatment device 21 made of an ion exchange resin and a water supply pump 23 and the suction side of the circulation pump 9 of the cooling water circulation system 6. The water stored in the recovered water tank 12 of the exhaust gas cooler 11 is joined to the cooling water flowing through the cooling water circulation system 6 by driving the water supply pump 23.

The blow water system 25 is connected to the lower part of the steam separator 8 and the exhaust gas cooler 11, and returns a part of the cooling water stored in the steam separator 8 to the recovered water tank 12 of the exhaust gas cooler 11. . The steam supply system 27 is a steam separator 8
And the heat load 28, the steam in the steam separator 8 is supplied to the heat load 28, while the condensed water discharge system 29
Is provided by being connected to the heat load 28 and the exhaust gas cooler 11, and the condensed water condensed by the heat load 28 is supplied to the exhaust gas cooler 11
To discharge.

A reforming steam system 30 supplies steam to the fuel reforming apparatus. With such a configuration, the reformed gas rich in hydrogen is supplied to the fuel cell 1 to the fuel electrode 2 and the air is supplied to the air electrode 3, whereby the fuel cell 1 causes a cell reaction to generate electricity. At this time, the heat generated during power generation is removed by the cooling water stored in the steam separator 8 flowing through the cooling passage 4 of the fuel cell 1 by the circulation pump 9, and the operating temperature of about 200 ° C. is maintained. The cooling water having a temperature of 160 to 170 ° C. that is obtained by cooling the fuel cell 1 is discharged as a two-phase flow of steam and water. Then, the discharged cooling water of the two-phase flow is cooled by the external cooling water in the cooler 7, a part of the steam is condensed and becomes water, which flows into the steam separator 8 and is separated into steam and water. To be done. The separated water is supplied to the cooling passage 4 of the fuel cell 1 as cooling water and circulates in the cooling water circulation system 6.

At this time, in the cooling water circulation system 6, the supply water flowing through the recovered water supply system 20 is sucked into the circulation pump 9 and added to the cooling water. In addition, by the blow water system 25,
A certain amount of the cooling water stored in the steam separator 8 is always returned to the exhaust gas cooler 11 and mixed in the recovered water in the exhaust gas cooler 11.

In the exhaust gas cooler 11, exhaust gas containing steam that is discharged from the air electrode during power generation of the fuel cell 1 via the exhaust gas supply system 31 and a reforming pipe for a reforming reaction in the fuel reformer. The flue gas after heating is introduced. On the other hand, in the recovered water circulation system 16, the water in the recovered water tank 12, which is cooled by the recovered water cooler 17 by the external cooling water by the recovered water circulation pump 18, is sent between the demister 13 and the deaerator 14 and sprinkled. To do. This sprinkled water is the deaerator 14
The gas dissolved in the water is deaerated, the exhaust air and the combustion exhaust gas flowing into the exhaust gas cooler 11 are cooled, and the steam contained therein is condensed to water of about 50 ° C. It is stored in the tank 12 as recovered water.

Further, the exhaust gas that does not condense passes through the deaerator 14 and after the water content contained in the exhaust gas is collected by the demister 13.
Released into the atmosphere. The water vapor separated by the water vapor separator 8 is supplied to the heat load 28 via the water vapor supply system 27, and is given heat to the heat load 28 to be cooled and condensed to become condensed water. It is returned to the vessel 11 and mixed with the collected water and stored in the collected water tank 12.

By the way, the cooling water and heat load 28 passing through the blow water system 25 in the recovery water tank 12 of the exhaust gas cooler 11
The quality of the recovered water mixed with the condensed water from the water treatment device 21 is improved by the ion exchange resin of the water treatment device 21, and is joined to the cooling water circulation system 6 by the water supply pump 23 to be added as cooling water. Flowing through. The water quality is improved in the water treatment device 21 in order to increase the electric resistance of the cooling water flowing in the fuel cell 1 and increase the cleanliness.

[0012]

The steam separated by the steam separator 8 is supplied to the heat load 28, the heat load 28 is heated, and the condensed water cooled and condensed is discharged to the exhaust gas cooler 11. It is stored in the recovered water tank 12. However, as described above, the collected water tank 12 also stores condensed water obtained by cooling the exhaust air from the fuel cell and the combustion exhaust gas from the fuel reformer, and condensing the water vapor contained therein.

Therefore, the components in the exhaust air and the combustion exhaust gas are also dissolved in the condensed water discharged from the heat load 28, and in particular, a large amount of carbon dioxide gas is dissolved, which imposes a heavy water treatment burden on the water treatment device 21. Become. At this time, generally the heat load 2
This tendency is remarkable because the amount of condensed water discharged from No. 8 is larger than that of the exhaust air or the combustion exhaust gas.

When the water treatment load of the water treatment device is heavy as described above, the life of the ion exchange resin is shortened, and the resin must be frequently replaced or a large capacity water treatment device must be used. . This requires the maintenance of the water treatment device, a large installation space, and has a drawback that the cost is high. In addition, the heat load 28, the steam supply system 27,
When the condensed water discharge system 29 has a problem in maintaining the water quality, it was also examined to improve the water quality of the condensed water discharged from the heat load 28.

The object of the present invention is to improve the water quality of the water stored in the exhaust gas cooler without increasing the load on the water treatment device, and to improve the water quality of the condensed water discharged from the heat load. A fuel cell heat output system is provided.

[0016]

In order to solve the above-mentioned problems, according to the present invention, a cooler for removing the heat generated during power generation of a fuel cell to cool the heated cooling water, and to send out from this cooler. A cooling water circulation system that includes a steam separator that separates the cooling water to be separated into steam and water, and a cooling water circulation system that circulates the separated water in the steam separator by supplying it to a fuel cell as a cooling water by a circulation pump, and a steam separator. In a heat output system of a fuel cell, a condensed water discharge system is provided, which includes a steam supply system for supplying the steam separated by the step S1 to a heat load, and a condensed water discharge system for discharging condensed water condensed and condensed by the heat load. The system shall join the cooling water circulation system.

In the heat output system of the fuel cell described above, the condensed water discharge system is made to join the suction side of the circulation pump of the cooling water circulation system. In the heat output system of the fuel cell described above, the condensed water discharge system is provided with a water treatment device capable of treating high temperature water.

[0018]

[Operation] The steam separated by the steam separator is supplied to the heat load through the steam supply system, and the condensed water discharge system for discharging the condensed water condensed by the heat load is joined to the cooling water circulation system. Condensate discharged from the heat load flows into the cooling water circulation system by confluence with the suction side of the circulation pump of the cooling water circulation system, and does not mix with the water stored in the exhaust gas cooler as in the conventional case. Therefore, the quality of the stored water is not mixed with condensed water from the heat load,
The amount of dissolved components of exhaust air from the fuel cell and the combustion gas from the fuel reformer, especially carbon dioxide, does not increase, and therefore the water treatment load on the water treatment device is reduced.

Further, by providing a water treatment device capable of treating high-temperature water with the condensed water discharge system for discharging condensed water from the heat load, the heat load, the steam supply system, and the condensed water discharge system maintain water quality. If not, the quality of the condensed water discharged from the heat load is improved. This improves the quality of the cooling water flowing through the cooling water circulation system.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a portion related to a fuel cell of a fuel cell power generator having a fuel cell heat output system according to an embodiment of the present invention. In FIG. 1, the same parts as those in the conventional example of FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.
1 differs from the conventional example in that a condensed water discharge system 29 for discharging condensed water from the heat load 28 is joined to the suction side of the circulation pump 9 of the cooling water circulation system 6.

With this configuration, the condensed water from the heat load 28 only flows through the cooling water circulation system 6 and does not flow into the exhaust gas cooler 11 as in the conventional case.
1. The condensed water is not mixed in the water stored in 1, and therefore the dissolved amount of the exhaust air from the fuel cell and the components of the combustion exhaust gas from the fuel reformer, particularly carbon dioxide gas, is dissolved in the stored water. Does not increase. Therefore, the water treatment load on the water treatment device 21 is reduced.

FIG. 2 is a system diagram of a part related to the fuel cell of the fuel cell power generator having the heat output system of the fuel cell according to another embodiment of the present invention. 2 is the same as FIG. 1 except that the condensed water discharge system 29 is provided with a high temperature water treatment device 33 capable of treating high temperature water. Here, the high temperature water treatment device 33
Is composed of an ion exchange resin that can be used at a temperature of condensed water of 160 to 170 ° C.

With such a configuration, the quality of the condensed water discharged from the heat load 28 is improved by the high temperature water treatment device 33.

[0024]

As is apparent from the above description, according to the present invention, since the condensed water from the heat load does not flow into the exhaust gas cooler as in the conventional case, it is stored in the exhaust gas cooler according to the above-mentioned configuration. The load of the water treatment device for improving the quality of the generated water is lightened, maintenance intervals and service life can be extended, and the installation space can be reduced.

Further, since the high temperature water treatment device is provided in the condensed water discharge system for discharging condensed water from the heat load, even if the water quality is not maintained in the heat load, the steam supply system and the condensed water discharge system, the condensed water is not maintained. Can easily improve the water quality, and as a result, can improve the water quality of the cooling water flowing through the cooling water circulation system.

[Brief description of drawings]

FIG. 1 is a system diagram of a portion related to a fuel cell of a fuel cell power generator including a heat output system of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a system diagram of a portion related to a fuel cell of a fuel cell power generator including a fuel cell heat output system according to another embodiment of the present invention.

FIG. 3 is a system diagram of a portion related to a fuel cell of a fuel cell power generator including a conventional fuel cell heat output system.

[Explanation of symbols]

 1 Fuel Cell 6 Cooling Water Circulation System 7 Cooler 8 Steam Separator 9 Circulation Pump 11 Exhaust Gas Cooler 21 Water Treatment Device 27 Steam Supply System 28 Heat Load 29 Condensate Discharge System 33 High Temperature Water Treatment Device

Claims (3)

[Claims] 1. A cooler that removes heat generated during power generation of a fuel cell to cool the heated cooling water, and a steam separator that separates the cooling water sent from this cooler into steam and water. A cooling water circulation system for supplying the water separated by the steam separator as cooling water to the fuel cell by a circulation pump for circulation, and a steam supply system for supplying the steam separated by the steam separator to a heat load; In a heat output system of a fuel cell including a condensed water discharge system that discharges condensed water that is condensed and condensed by steam under a heat load, the condensed water discharge system is combined with a cooling water circulation system. Heat output system. 2. The heat output system for a fuel cell according to claim 1, wherein the condensed water discharge system is joined to the suction side of the circulation pump of the cooling water circulation system. 3. The heat output system for a fuel cell according to claim 1, wherein the condensed water discharge system is provided with a water treatment device capable of treating high temperature water.