JP2000082477A - Fuel cell generation plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell generation plant capable of efficiently recovering heat from exhaust gas. SOLUTION: An exhaust heat recovery heat exchanger 19 is arranged at the upstream side of an exhaust gas condenser 13, so as to supply fuel exhaust gas 11 exhausted from a reformer 3 and exhaust air 12 exhausted from a fuel cell mainbody 1. In this exhaust heat recovery heat exchanger 19, the exhaust heat of the fuel exhaust gas 11 and exhaust air 12 is recovered to extract hot water 20 at a temperature of 85 deg.C or so to be supplied to a single utility absorption refrigerator 21.

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 plant, and more particularly to a fuel cell power plant that recovers exhaust heat from a fuel cell main body as hot water and supplies it to a hot water utilization device such as a refrigerator.

[0002]

2. Description of the Related Art A fuel cell power plant generates electricity directly by electrochemically reacting hydrogen obtained by reforming a fuel such as natural gas with oxygen in the air. It is obtained. Moreover, it has been evaluated as a power generation system that emits little air pollutants and has low environmental noise, and has excellent environmental performance.

An example of such a fuel cell power plant will be described with reference to FIG. In FIG. 1, a fuel cell body 1 includes a matrix (not shown) impregnated with phosphoric acid as an electrolyte, a fuel electrode (anode) 1a to which fuel gas is supplied, and an air electrode (cathode) 1 to which air is supplied.
A unit cell is formed by sandwiching the unit cell with the unit b, and a large number of the unit cells are stacked.

A raw fuel 2 such as natural gas is supplied to a reaction section 3a of a reformer 3, where it is reformed into a hydrogen-rich reformed gas 4 by a reforming reaction.
Supplied to On the other hand, the reaction air 5 is supplied to the air electrode 1b of the fuel cell main body 1 by an air supply device 6 such as a blower. Then, in the fuel cell body 1, the reformed gas 4
The hydrogen contained therein reacts with the oxygen in the reaction air 5 to generate electricity.

In the fuel cell body 1, since heat of reaction is generated at the same time as power generation, a cooling plate 1c is provided for the purpose of keeping the operating temperature of the fuel cell body 1 at about 200 ° C. The cooling plate 1c performs cooling by supplying the battery cooling water 7. The cell cooling water 7 has a two-phase flow at the outlet of the fuel cell main body 1, and is separated into steam and water by the steam separator 8. The battery cooling water 7 from which the steam has been separated by the steam separator 8 is pressurized by a pump 9 and cooled by a cooler 10 before being supplied to the fuel cell main body 1.

On the other hand, the reformed gas 4 which has completed the reaction at the fuel electrode 1 a of the fuel cell body 1 is supplied to the burner 3 b of the reformer 3.
Supplied to Unreacted hydrogen remaining in the reformed gas 4 becomes a heat source for the reaction section 3a by burning in the burner section 3b, and the reformed gas 4
It is discharged from the reformer 3 as 1. Further, the reaction air 5 that has completed the reaction at the air electrode 1b of the fuel cell body 1 is
It is exhausted as exhaust air 12.

[0007] The fuel exhaust gas 11 and the exhaust air 12 are supplied to an exhaust gas condenser 13, respectively.
After the cooling, the water is separated into plant exhaust gas 14 and condensed water 15. Then, usually, the plant exhaust gas 14 is directly discharged to the atmosphere, and the condensed water 15 is reused in the plant. On the other hand, the secondary cooling water 16 is passed through the low temperature side of the exhaust gas condenser 13, and the fuel exhaust gas 11 and the exhaust air 1
2 is supplied to the waste heat utilizing heat exchanger 17 by the secondary cooling water 16,
After the heat exchange, the heat is supplied to an external hot water utilization facility 18.

[0008]

The main purpose of the exhaust gas condenser 13 used in the conventional fuel cell power plant is to condense and recover the water vapor contained in the fuel exhaust gas 11 and the exhaust air 12. And had Therefore, the secondary cooling water 16 needs a constant flow rate, and it has been difficult to reduce the flow rate. Therefore, there is a problem that the temperature of the hot water for utilizing the exhaust heat in the exhaust heat utilizing heat exchanger 17 cannot be increased. That is,
In a conventional fuel cell power plant, it has been difficult to efficiently recover heat from the fuel exhaust gas 11 and the exhaust air 12.

The present invention has been proposed to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide a fuel cell power plant capable of efficiently recovering heat from exhaust gas.

[0010]

In order to achieve the above object, the invention according to claim 1 comprises a fuel cell main body having an anode and a cathode and generating electricity from hydrogen and oxygen in the air; Reformer for reforming into a hydrogen-rich reformed gas and supplying the reformed gas to the anode, and burning the unreacted hydrogen of the reformed gas after the reaction in the fuel cell main body and discharging it as fuel exhaust gas; A fuel cell power plant comprising: an air supply device that supplies air to the fuel cell; and an exhaust gas heat exchanger that condenses and recovers water vapor contained in the fuel exhaust gas and the exhaust air after the reaction in the fuel cell body. The fuel exhaust gas discharged from the vessel and the exhaust air after the reaction in the fuel cell main body are supplied, and the exhaust heat is recovered as hot water, and the exhaust heat after the recovery of the exhaust heat is supplied. Charge and exhaust gas and exhaust heat recovery heat exchanger for supplying the exhaust air to the heat exchanger for the exhaust gas, is characterized in that it comprises a hot water supply means for supplying the hot water to the hot water utilization device.

According to the first aspect of the present invention, the exhaust heat recovery heat exchange is performed before the fuel exhaust gas discharged from the reformer and the exhaust air discharged from the fuel cell body are supplied to the exhaust gas heat exchanger. In order to increase the temperature of the hot water for utilizing the waste heat, the flow rate of the hot water can be reduced in order to supply the waste heat to the heat exchanger and recover the waste heat in the waste heat recovery heat exchanger. Therefore, heat can be efficiently recovered from the exhaust gas. Then, by adjusting the temperature of the hot water to an appropriate temperature, the hot water can be supplied to a hot water utilization device such as a single-effect absorption refrigerator to be operated.

[0012] In the fuel cell power plant according to the second aspect of the present invention, in the first aspect of the invention, the exhaust gas heat exchanger directly contacts the fuel exhaust gas and the exhaust air with cooling water to generate steam. It is a direct contact heat exchanger for condensation and recovery.

According to the second aspect of the present invention, since a direct contact heat exchanger in which the fuel exhaust gas and the exhaust air directly contact the cooling water is used as the exhaust gas heat exchanger, high heat transfer characteristics can be obtained. As a result, the size of the exhaust gas heat exchanger can be reduced.

According to a third aspect of the present invention, there is provided a fuel cell power plant according to the first or second aspect, further comprising a cooler for cooling the fuel cell main body by supplying cooling water into the fuel cell main body. Supplying the hot water to the hot water utilization device after supplying the hot water to the cooler and exchanging heat with the cooling water recovered from the fuel cell body in the cooler. Features.

According to the third aspect of the present invention, the hot water taken out in the exhaust heat recovery heat exchanger is supplied to a cooler for cooling the fuel cell main body, and is recovered from the fuel cell main body in the cooler. After recovering the exhaust heat of the cooling water, it is supplied to the hot water utilization device. For this reason, the exhaust heat recovery efficiency can be further improved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a fuel cell power plant according to the present invention will be described below with reference to the drawings. The same members as those of the conventional fuel cell power plant shown in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

[1. First Embodiment] FIG. 1 is a system configuration diagram of a fuel cell power plant according to a first embodiment of the present invention. In the fuel cell power plant according to the present embodiment, as shown in FIG. 1, an exhaust heat recovery heat exchanger 19 is arranged upstream of the exhaust gas condenser 13. That is, the exhaust heat recovery heat exchanger 19 is supplied with the fuel exhaust gas 11 discharged from the reformer 3 and the exhaust air 12 discharged from the fuel cell body 1. Further, the exhaust heat recovery heat exchanger 19 is provided between the fuel exhaust gas 11 and the exhaust air 1.
2 is used as a high-temperature heat source to extract hot water 20 of about 85 ° C.

Further, in the present embodiment, a single-effect absorption refrigerator 21 as a hot water utilization device is disposed, and the hot water 20 extracted in the exhaust heat recovery heat exchanger 19 is provided.
Is supplied by a pipe (not shown) as hot water supply means, and the hot water 20 operates as a heat source. The hot water 20 supplied to the single-effect absorption refrigerator 21 is returned to the exhaust heat recovery heat exchanger 19 again via the pump 22 as hot water supply means.

According to the present embodiment having the above configuration, the following operation and effect can be obtained. That is, the reformed gas 4 that has completed the reaction at the fuel electrode 1a of the fuel cell body 1 is supplied to the burner section 3b of the reformer 3, and the unreacted hydrogen in the reformed gas 4 is burned by the burner section 3b. Then, the reformed gas 4 is discharged from the reformer 3 as the fuel exhaust gas 11. On the other hand, the reaction air 5 that has completed the reaction at the air electrode 1 b of the fuel cell main body 1 is discharged as exhaust air 12.

The fuel exhaust gas 11 and the exhaust air 12 are supplied to an exhaust heat recovery heat exchanger 19, cooled in the exhaust heat recovery heat exchanger 19, and then supplied to the exhaust gas condenser 13 as exhaust gas 23. You. In the exhaust heat recovery heat exchanger 19, hot water 20 of about 85 ° C. is taken out using the fuel exhaust gas 11 and the exhaust air 12 as high-temperature heat sources and supplied to the single-effect absorption refrigerator 21. Thus, the single-effect absorption refrigerator 21 used for air conditioning or the like operates.

As described above, in the present embodiment, since the exhaust heat recovery from the fuel exhaust gas 11 and the exhaust air 12 is performed in the exhaust heat recovery heat exchanger 19, the single-effect absorption refrigerator 21
Can be changed.
That is, since the exhaust heat is not recovered in the exhaust gas condenser 13 for utilizing the exhaust heat as in the related art, and the hot water 20 is recovered separately from the secondary cooling water 16, the exhaust heat is reduced by reducing the flow rate of the hot water 20. The temperature of the hot water 20 for use can be raised.

Here, in the exhaust heat recovery heat exchanger 19,
In order to make the temperature difference in the heat exchange state between the fuel exhaust gas 11 and the exhaust air 12 side and the hot water 20 side appropriate, heat is recovered at the outlet of the exhaust heat recovery heat exchanger 19 to such an extent that water vapor in the exhaust gas 23 does not condense. Then, it is desirable to set the flow rate of the hot water 20. By appropriately setting the flow rate of the hot water 20, the temperature of the hot water 20 to be taken out is set to 85 ° C.
As a degree, the single-effect absorption refrigerator 21 can be operated.

As described above, according to the present embodiment, the provision of the exhaust heat recovery heat exchanger 19 makes it possible to
0 can be taken out, whereby the single-effect absorption refrigerator 21 can be operated. That is, heat recovery from the fuel exhaust gas 11 and the exhaust air 12 can be performed efficiently.

[2. Second Embodiment] FIG. 2 is a system configuration diagram of a fuel cell power plant according to a second embodiment of the present invention. In the fuel cell power plant according to the present embodiment, as shown in FIG. 2, a direct contact heat exchanger 24 is arranged instead of the exhaust gas condenser 13. In the direct contact heat exchanger 24, the exhaust gas 23 from the exhaust heat recovery heat exchanger 19 comes into direct contact with the cooling water 25, whereby the water vapor in the exhaust gas 23 is condensed and recovered. The cooling water 25 containing the condensed water vapor is taken out through a pump 26 and then separated into the condensed water 15 and the cooling water 25. The condensed water 15 is reused in the plant, and the cooling water 25 is directly contacted. It is configured to be returned to the heat exchanger 24. Further, the plant exhaust gas 14 left in the direct contact heat exchanger 24 is directly discharged to the atmosphere as in the conventional case.

According to the present embodiment having the above configuration, the following operation and effect can be obtained. That is, the fuel exhaust gas 11 discharged from the reformer 3 and the fuel cell body 1
The exhaust air 12 discharged from is supplied to an exhaust heat recovery heat exchanger 19 and cooled, and then supplied as an exhaust gas 23 to a direct contact heat exchanger 24. Here, the hot water 20 is taken out in the exhaust heat recovery heat exchanger 19, but the description is omitted because it is the same as in the first embodiment.

The exhaust gas 23 supplied to the direct contact heat exchanger 24 comes into direct contact with the cooling water 25 in the direct contact heat exchanger 24. Then, the steam in the exhaust gas 23 is condensed, and the cooling water 25 containing the steam is discharged from the direct contact heat exchanger 24. Of the cooling water 25, the condensed water 15 is reused in the plant, and the cooling water 25 is returned to the direct contact heat exchanger 24 again.

As described above, according to the present embodiment, the effect obtained by the above-described first embodiment is similarly obtained, and the direct contact heat exchanger 24 is provided as a condenser for the exhaust gas 23. As a result, the exhaust gas 23 comes into direct contact with the cooling water 25, so that higher heat transfer characteristics can be obtained as compared with a partition type heat exchanger, and the size of the condenser can be reduced.

[3. Third Embodiment] FIG. 3 is a system configuration diagram of a fuel cell power plant according to a third embodiment of the present invention. In the fuel cell power plant according to the present embodiment, as shown in FIG.
The hot water 20 taken out of the refrigerator is supplied to the cooler 10. The cooler 10 is conventionally provided to supply the battery cooling water 7 to a cooling plate 1c provided for maintaining the operating temperature of the fuel cell main body 1 at an appropriate value. In the present embodiment, the cooler 1
0 indicates that the hot water 2 is recovered by recovering the exhaust heat from the battery cooling water 7 which has recovered the exhaust heat generated in the fuel cell body 1.
After the temperature of 0 is raised, it is supplied to the single-effect absorption refrigerator 21.

According to the present embodiment having the above configuration, the following operation and effect can be obtained. That is, in the fuel cell main body 1, reaction heat is generated when hydrogen in the reformed gas 4 reacts with oxygen in the reaction air 5 to generate electricity, but the operating temperature of the fuel cell main body 1 is controlled by the cooling plate 1c. Is maintained at an appropriate value. That is, the battery cooling water 7 supplied to the cooling plate 1c is
The exhaust heat in the inside is recovered and separated into steam and water by the steam separator 8. Then, the battery cooling water 7 from which the vapor has been separated is pressurized by the pump 9, then cooled by the cooler 10, and supplied to the cooling plate 1c.

On the other hand, the fuel exhaust gas 11 discharged from the reformer 3 and the exhaust air 12 discharged from the fuel cell main body 1 are supplied to an exhaust heat recovery heat exchanger 19 where they are cooled. Supplied to Here, the exhaust heat recovery heat exchanger 1
The hot water 20 taken out at 9 is supplied to the cooler 10.

In the cooler 10, the above-mentioned battery cooling water 7 exchanges heat with hot water 20. In other words, the battery cooling water 7 is cooled by recovering the exhaust heat recovered from the fuel cell main body 1 by the hot water 20. Then, the warm water 20 whose temperature has been raised by collecting exhaust heat from the battery cooling water 7 is supplied to the single-effect absorption refrigerator 21.
As a result, the single-effect absorption refrigerator 21 operates.

As described above, according to the present embodiment, the hot water 20 extracted from the exhaust heat recovery heat exchanger 19 is supplied to the cooler 1 provided for recovering the exhaust heat from the fuel cell body 1.
0, and the heat exchange with the battery cooling water 7 can further improve the exhaust heat recovery efficiency.

[4. Fourth Embodiment] FIG. 4 is a system configuration diagram of a fuel cell power plant according to a fourth embodiment of the present invention. In the fuel cell power plant according to the present embodiment, as shown in FIG. 4, a direct contact heat exchanger 24 is provided downstream of the exhaust heat recovery heat exchanger 19, as in the second embodiment shown in FIG. Are located. Further, similarly to the third embodiment shown in FIG. 3, the hot water 20 extracted from the exhaust heat recovery heat exchanger 19 is supplied to the cooler 10.

That is, in the direct contact heat exchanger 24, when the exhaust gas 23 comes into direct contact with the cooling water 25, the water vapor in the exhaust gas 23 is condensed and recovered. Then, after the cooling water 25 containing the water vapor is taken out and separated into the condensed water 15 and the cooling water 25, only the cooling water 25 is returned to the direct contact heat exchanger 24, and the condensed water 15 is separated in the plant. Reused.

On the other hand, the hot water 20 extracted in the exhaust heat recovery heat exchanger 19 is supplied to the battery cooler 7 in the cooler 10.
After the heat is exchanged with the exhaust gas and the exhaust heat recovered from the fuel cell main body 1 is recovered, the temperature is increased, and then supplied to the single-effect absorption refrigerator 21.

As described above, according to the embodiment, by providing the direct contact heat exchanger 24, the condenser of the exhaust gas 23 can be downsized, and the exhaust heat recovery heat exchange can be performed. The hot water 20 taken out of the vessel 19 is cooled
In this case, since the heat is further exchanged, the exhaust heat recovery efficiency can be further improved.

[0037]

As described above, according to the present invention,
Exhaust heat is efficiently recovered from the combustion exhaust gas and exhaust air discharged after the reaction in the fuel cell main body, whereby a hot water utilization device such as a single-effect absorption refrigerator can be operated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a fuel cell power plant according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a fuel cell power plant according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a fuel cell power plant according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a fuel cell power plant according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional fuel cell power plant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel cell main body 1a ... Fuel electrode 1b ... Air electrode 1c ... Cooling plate 2 ... Raw fuel 3 ... Reformer 3a ... Reactor 3b ... Burner part 4 ... Reformed gas 5 ... Reaction air 6 ... Air supply device 7 ... Battery cooling water 8 ... Steam separator 9 ... Pump 10 ... Cooler 11 ... Combustion exhaust gas 12 ... Exhaust air 13 ... Exhaust gas condenser 14 ... Plant exhaust gas 15 ... Condensed water 16 ... Secondary cooling water 17 ... Exhaust heat utilization heat exchange 18: Hot water utilization equipment 19: Exhaust heat recovery heat exchanger 20: Hot water 21: Single-effect absorption refrigerator 22 ... Pump 23 ... Exhaust gas 24 ... Direct contact heat exchanger 25 ... Cooling water 26 ... Pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Motohiro Takahashi 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Keihin Plant, Toshiba Corporation (72) Maki Ishizawa 3-19, Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Inside Nippon Telegraph and Telephone Corporation (72) Masaki Yamamoto 3-19-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Within Telegraph and Telephone Corporation (72) Shigeru Okada 3-19, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation (72) Inventor Tsuneo Uekusa 3-4-1 Shibaura, Minato-ku, Tokyo (72) Within NTT Facilities Corporation (72) Inventor Shigenori Waratani 3-chome, Shibaura, Minato-ku, Tokyo No. 1 F-term in NTT Facilities (Reference) 5H027 AA02 BA01 BC11 CC06 DD06

Claims (3)

[Claims] A fuel cell main body having an anode and a cathode for generating electricity from hydrogen and oxygen in the air; a fuel reformed into a hydrogen-rich reformed gas and supplied to the anode; A reformer that burns unreacted hydrogen of the reformed gas after reaction in the battery body and discharges it as fuel exhaust gas, an air supply device that supplies air to the cathode, and a fuel exhaust gas and after reaction in the fuel cell body. A fuel cell power plant comprising an exhaust gas heat exchanger for condensing and recovering water vapor contained in the exhaust air of the fuel cell, wherein the fuel exhaust gas discharged from the reformer, and the exhaust air after reaction in the fuel cell body. And recovers the exhaust heat thereof as hot water and supplies the fuel exhaust gas and the exhaust air after the recovery of the exhaust heat to the exhaust gas heat exchanger. And exchangers, fuel cell power plant, characterized in that it comprises a hot water supply means for supplying the hot water to the hot water utilization device. 2. The heat exchanger for exhaust gas is a direct contact heat exchanger that condenses and recovers steam by bringing the fuel exhaust gas and the exhaust air into direct contact with cooling water. A fuel cell power plant as described. 3. A cooling device for cooling the fuel cell main body by supplying cooling water into the fuel cell main body, wherein the hot water supply means supplies the hot water to the cooler,
3. The fuel cell power plant according to claim 1, wherein the hot water is supplied to the hot water utilization device after heat exchange with the cooling water recovered from the fuel cell main body in the cooler. 4.