JPH10214633A - Phosphoric acid type fuel cell power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphoric acid type fuel cell power generation device which is improved so as to reduce the maintenance frequency of a make-up water supply system. SOLUTION: A phosphoric acid removal device 2, which is a device for removing phosphoric acid contained in recovery water 61a, is inserting installed in a recovery water 61a passage between a heat exchanger 61 and the water tank 51 of a make-up water supply system 5. A neutralizer neutralizing and removing the phosphoric acid or an ion-exchange resin removing the phosphoric acid is loaded in the phosphoric acid removal device 2. Since the phosphoric acid contained in the recovery water 61a is removed by the neutralizer or the ion-exchange resin, the contained phosphoric acid in the recovery water 2a flowing out from the phosphoric acid removal device 2 and lowing into the water tank 51 is significantly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphoric acid fuel cell power generation system having a makeup water supply system for supplying makeup water by using recovered water obtained by collecting water contained in a reacted oxidizing gas. The present invention relates to an apparatus, and relates to an improved configuration for reducing the maintenance frequency of a makeup water supply system.

[0002]

2. Description of the Related Art A fuel cell is a power generation apparatus that electrochemically generates DC power using a fuel gas and an oxidizing gas as reaction gases. As is well known, this fuel cell has a higher conversion efficiency into electric energy and a lower emission of air pollutants such as carbon dioxide and nitrogen oxides than other power generation devices. Therefore, it is expected as a so-called clean energy source. Various types of fuel cells, such as a phosphoric acid type and a molten carbonate type, are already known as fuel cells depending on the type of electrolyte used.

[0003] In a phosphoric acid fuel cell using phosphoric acid as an electrolyte, hydrogen or a hydrogen-rich fuel gas obtained by steam reforming a hydrocarbon-based fuel is often used as a fuel gas. Air is used as the oxidant gas. This phosphoric acid type fuel cell is composed of a matrix supporting phosphoric acid and a pair of porous members having a fuel gas passage and an oxidant gas flow passage which sandwich the matrix and through which a fuel gas and an oxidant gas flow respectively. Has a unit cell composed of a fuel electrode and an oxidant electrode as gas diffusion electrodes. In order to operate the phosphoric acid fuel cell with high efficiency, the unit cell needs to be about 20 units.
It must be maintained at a temperature of 0 ° C.

[0004] During the electrochemical reaction, heat of reaction is generated in the unit cell.
In order to operate the phosphoric acid type fuel cell while maintaining the temperature at [° C.], the phosphoric acid type fuel cell is provided with a cooling body which plays a role of removing reaction heat generated in the unit cell. Therefore, the phosphoric acid type fuel cell is generally configured by interposing a cooling body every time a plurality of unit cells are stacked, and stacking a plurality of stacked bodies of the plurality of unit cells and the cooling body. is there.

A water-cooled phosphoric acid fuel cell using water for removing reaction heat generated in a unit cell requires cooling water for this purpose. Due to the above-mentioned structure of the phosphoric acid type fuel cell, this cooling water is passed through cooling bodies having different electric potentials, so pure water is selected because it needs to have a high electric resistivity value. Is common. Further, in the case of a phosphoric acid type fuel cell power generation device accompanied by a fuel reformer for producing a hydrogen-rich fuel gas obtained by steam reforming a hydrocarbon-based fuel as a fuel gas source, the fuel reforming is performed. It is necessary to constantly supply steam to the porcelain. In a phosphoric acid fuel cell power generator equipped with a water-cooled phosphoric acid fuel cell or a phosphoric acid fuel cell power generator accompanied by a fuel reformer, pure water is supplied to supply the cooling water and steam. A pure water circulation system for circulating and continuously supplying is provided.

[0006] In the pure water circulation system, the steam is discharged through the pure water circulation system in order to release steam to adjust the temperature of the pure water and to supply steam to the fuel reformer. Since the flowing pure water is consumed, it is necessary to supply pure water.
For this reason, the phosphoric acid type fuel cell power generator provided with the pure water circulation system is also provided with a makeup water supply system in order to supply makeup water, which is pure water to be supplemented, to the pure water circulation system. . Then, as a water source of the makeup water, a reacted oxidant gas discharged from the phosphoric acid type fuel cell after being subjected to the electrochemical reaction, or when a fuel reformer is attached, The recovered water recovered from the combustion exhaust gas of the fuel reformer is mainly used. In addition, when the required amount of makeup water is insufficient with the recovered water alone, tap water is often used as a source of makeup water in many cases.

A conventional phosphoric acid fuel cell power generator provided with a makeup water supply system will be described below with reference to FIG. FIG. 4 is a process flow diagram showing a main part of a conventional phosphoric acid fuel cell power generator. FIG.
9 is a phosphoric acid provided with a phosphoric acid type fuel cell 8, an air blower 7 as a means for supplying air 7a as an oxidizing gas, heat exchangers 61 and 62, and a makeup water supply system 5. A fuel cell power generation device.

In FIG. 4, the fuel cell 8 is shown as having only a fuel electrode 81, an oxidant electrode 82, and a cooling body 83 for convenience of illustration, but the fuel cell 8 is actually constructed as described above. Have been. The fuel electrode 81 has
The fuel gas 81a is supplied from a hydrogen gas source (not shown) or a fuel reformer (not shown). Pure water as cooling water is supplied to the cooling body 83 from a pure water circulation system (not shown). After the air 7a is subjected to an electrochemical reaction at the oxidant electrode 82, it is converted into a reacted air 7b (which is a reacted oxidant gas in the case of the fuel cell 8).
Exhausted from 2.

The reacted air 7b immediately after being discharged from the oxidant electrode 82 has a temperature close to the operating temperature of the fuel cell 8 described above, and is guided to the heat exchanger 61 and And heat exchange with the air 7a immediately after being discharged. Thereby, while preheating the air 7a,
Part of the water vapor generated during the electrochemical reaction contained in the reacted air 7b is recovered as recovered water 61a.
The reacted air 7c, which is the reacted air 7b from which part of the water vapor has been removed in the heat exchanger 61, is still high in temperature for the make-up water supply system 5, and is subsequently guided to the heat exchanger 62.

[0010] In the heat exchanger 62, the reacted air 7c, and when the fuel reformer is installed in the phosphoric acid type fuel cell power generator 9, in addition to the reacted air 7c, the fuel is discharged from the fuel reformer. The known combustion flue gas 63 (generally the combustion flue gas whose heat has been recovered via a heat exchanger) flows thereinto and is cooled by the cooling water 62a. The cooling water 62a, which has become high temperature by removing heat from the reacted air 7c and the combustion exhaust gas 63, is discharged to the outside of the phosphoric acid fuel cell power generator 9 (such as a hot water demand destination) as waste water 62b. In the heat exchanger 62, a part of the steam contained in each of the reacted air 7c and the combustion exhaust gas 63 is condensed by cooling the reacted air 7c and the combustion exhaust gas 63 by the cooling water 62a. The reacted air containing the condensed water and the exhaust gas 62c, which is the combustion exhaust gas, are guided to the makeup water supply system 5 together with the recovered water 61a.

[0011] In this case, the makeup water supply system 5
It is provided with a water tank 51, a water purification device 52, and a pump device 53. The water tank 51 contains recovered water 61a,
Along with the exhaust gas 62c, a tap water 59 is also introduced as required. In many cases, as the clean water 59, clean water from which chlorine or the like has been removed by passing through a known activated carbon filter or the like is used. Condensed water contained in the exhaust gas 62c is separated in the water tank 51, and the exhaust gas 51b, which is a gas component in the exhaust gas 62c, is discharged to the outside of the phosphoric acid fuel cell power generator 9. Then, the condensed water in the recovered water 61a and the exhaust gas 62c, and the clean water 59 are temporarily stored in the water tank 51 and then supplied to the pure water purification device 52 by the pump device 53.

The water purification device 52 is a device for purifying water supplied from the water tank 51 by using an ion exchange resin. The ion exchange resin loaded into the water purification apparatus 52 is a combination of a cation exchange resin and an anion exchange resin. As the ion exchange resin, an ion exchange resin generally used for purification of clean water is used. An exchange resin agent is used. The ratio between the cation exchange resin and the anion exchange resin in the water purification apparatus 52 is set to 1: 2 as in the case of general pure water treatment. The replenishing water 58 which has been treated by the deionizing device 52 to be pure water is supplied to a pure water circulation system via a pump device (not shown) as necessary.

[0013]

The phosphoric acid fuel cell power generator according to the prior art, for example, the phosphoric acid fuel cell power generator 9, having the above-described structure, requires relatively little use of clean water. By volume, the phosphoric acid fuel cell power plant can be operated. However, the conventional phosphoric acid fuel cell power generator has the following problems, and improvement thereof is desired. That is, the reacted oxidizing gas contains phosphoric acid used as an electrolyte in a phosphoric acid type fuel cell (for example, the fuel cell 8). Phosphoric acid contained in the reacted oxidant gas is contained in the recovered water (for example, the recovered water 61a) recovered in the heat exchanger (for example, the heat exchanger 61), and is supplied with make-up water. Into the system (eg, make-up water supply system 5). The purifying apparatus (for example, the purifying apparatus 52) of the make-up water supply system must also treat the phosphoric acid flowing into the make-up water supply system, and the phosphoric acid is a strong acid. Insufficient ion exchange capacity of the anion exchange resin is caused. As a result, it is necessary to frequently change the ion exchange resin loaded in the water purification apparatus,
For example, its maintenance costs are high.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a phosphoric acid type fuel cell power generator improved to reduce the frequency of maintenance of a makeup water supply system. Is to do.

[0015]

The objects of the present invention are as follows: 1) electrochemically using a phosphoric acid as an electrolyte, a fuel gas such as hydrogen, and an oxidizing gas such as air as a reaction gas; A phosphoric acid fuel cell that generates electricity,
A heat exchanger that recovers moisture from the reacted oxidant gas discharged from the fuel cell after being subjected to an electrochemical reaction;
A replenishing water supply system for supplying at least the recovered water recovered by the heat exchanger as a replenishing water for water used in a fuel cell or the like via a deionization device loaded with an ion exchange resin. In a phosphoric acid type fuel cell power generator, a phosphate removing device for removing the phosphoric acid contained in the recovered water is installed in the flow path of the recovered water between the heat exchanger and the makeup water supply system. Or 2) In the means described in the above item 1, the phosphoric acid removing device is configured to remove phosphoric acid contained in recovered water by neutralizing phosphoric acid with a neutralizing agent. (3) In the means described in the item (1), the phosphoric acid removing device is achieved by removing phosphoric acid contained in recovered water with an ion exchange resin.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In the following description of this section, the same parts as those of the conventional phosphoric acid fuel cell power generator shown in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted.
In addition, in the drawings used in the following description of this section, only reference numerals shown in FIG. 4 are representative as much as possible.

FIG. 1 is a process flow diagram showing a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a phosphoric acid fuel cell power generator 9 according to the conventional example shown in FIG.
This is a phosphoric acid type fuel cell power generator in which a phosphoric acid removing device 2 is additionally provided. The phosphoric acid removing device 2 is a device that removes the phosphoric acid contained in the recovered water 61a, and is disposed in a flow path of the recovered water 61a between the heat exchanger 61 and the water tank 51 of the makeup water supply system 5. It is inserted and installed.

The phosphoric acid removing device 2 is loaded with, for example, a neutralizing agent for neutralizing and removing phosphoric acid and an ion exchange resin for removing phosphoric acid. Since the phosphoric acid contained in the recovered water 61a is removed by the neutralizing agent or the ion exchange resin, the phosphorus contained in the recovered water 2a flowing out of the phosphoric acid removing device 2 and flowing into the water tank 51 is contained. The amount of acid is almost zero, or even if phosphoric acid is contained, its amount is greatly reduced as compared with the case of the recovered water 61a. Thus, the water stored in the water tank 51 (the makeup water supply system 5)
(Which is water to be treated by the water purification device 52 of the present invention) is greatly reduced, so that the life of the ion exchange resin loaded in the water purification device 52 is extended. As a result, the exchange frequency of the ion-exchange resin loaded in the water purification device 52 can be suppressed to approximately the same frequency as in the case where ordinary clean water is to be treated.

The neutralizing agent to be charged into the phosphoric acid removing device 2 is, for example, granular calcium carbonate (lime).
Can be used. When the recovered water 61a is treated using the granular neutralizing agent (calcium carbonate), sludge-like processed products are deposited around the granular neutralizing agent. The flow resistance is sequentially increased. Therefore, the neutralizing agent needs to be replaced from time to time.

The capacity of the anion exchange resin is increased, for example, the ratio of the cation exchange resin to the anion exchange resin is 1: 3 to 1: 4, etc. Also, an ion exchange resin using a combination of a cation exchange resin and an anion exchange resin, or
Only an anion exchange resin which is an ion exchange resin for converting a strong acid into a weak acid can be used. In the case of treating the recovered water 61a using these ion exchange resins, unlike the case of using the above-described calcium carbonate, it can be handled as a treatment product is not generated in practical use. Therefore, the above-described neutralizing agent is used. This has a feature that the phenomenon that occurs in the case, that is, the phenomenon that the flow resistance to the recovered waters 61a and 2a is increased by the processing product does not occur.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description of this section, the phosphoric acid fuel cell power generator according to the embodiment of the present invention shown in FIG. 1 and the conventional phosphoric acid fuel cell power generator shown in FIG. The same reference numerals are given to the same parts as those described above, and description thereof is omitted. Further, in the drawings used in the following description of this section, only reference numerals shown in FIGS. 1 and 4 are represented as much as possible.

Embodiment 1 FIG. 2 is a process flow diagram showing a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 and 2. In FIG. 2, reference numeral 1A denotes a phosphoric acid fuel cell power generator in which a phosphoric acid removing device 3 is added to the conventional phosphoric acid fuel cell power generator 9 shown in FIG.
The phosphoric acid removing device 3 is a device that removes the phosphoric acid contained in the recovered water 61a by using a neutralizing agent.
It is inserted and installed in the flow path of the recovered water 61 a between the water supply tank 1 and the water tank 51 of the makeup water supply system 5. The neutralizing agent loaded into the phosphoric acid removing device 3 is granular calcium carbonate (lime).

The phosphoric acid fuel cell power generator 1A according to the first embodiment has the above-described configuration. Therefore, as described in the embodiment of the invention, the phosphoric acid fuel cell power generator 1A
A indicates that the exchange frequency of the ion-exchange resin loaded in the pure water purification device 52 can be reduced by greatly reducing the amount of phosphoric acid contained in the recovered water 3a flowing out of the phosphoric acid removal device 3 and flowing into the water tank 51. Can be suppressed to almost the same frequency as in the case where normal tap water is treated.

Embodiment 2 FIG. 3 is a process flow diagram showing a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 and 3. In FIG. 3, reference numeral 1B denotes a phosphoric acid fuel cell power generator in which a phosphoric acid removing device 4 is added to the conventional phosphoric acid fuel cell power generator 9 shown in FIG.
The phosphoric acid removing device 4 is a device for removing the phosphoric acid contained in the recovered water 61a, and comprises a heat exchanger 61 and a makeup water supply system 5
Is installed in the flow path of the recovered water 61a between the water tank 51 and the water tank 51.

The phosphoric acid removing device 4 includes a drain tank 41 for temporarily storing collected water 61 a, an ion exchange resin device 42, and a collected water 61 stored in the drain tank 41.
a from a drain tank 41 to an ion exchange resin device 42 and a pump device 43. The ion-exchange resin device 42 is loaded with an ion-exchange resin in which the ratio of the cation-exchange resin to the anion-exchange resin is 1: 4 and the cation-exchange resin and the anion-exchange resin are used in combination. Then, the ion exchange resin device 42
The ion-exchange resin agent of the same type as the ion-exchange resin agent used in the pure water purification device 52 of the makeup water supply system 5 is used.

The phosphoric acid fuel cell power generator 1B according to the second embodiment has the above-described configuration. Therefore, as described in the embodiment of the invention, the phosphoric acid fuel cell power generator 1B
B is the frequency of exchange of the ion exchange resin loaded in the pure water purification device 52 because the amount of phosphoric acid contained in the recovered water 4a flowing out of the phosphoric acid removal device 4 and flowing into the water tank 51 can be drastically reduced. Can be suppressed to almost the same frequency as in the case where normal tap water is treated.

[0027]

According to the phosphoric acid fuel cell power generator of the present invention, the following effects can be obtained by adopting the structure described in the section for solving the above-mentioned problems.
The ion exchange resin loaded in the water purification system of the make-up water supply system should be treated by adopting the constitution according to the above items (1) and (2). Since the concentration of phosphoric acid contained in water is drastically reduced, the exchange frequency of the ion exchange resin can be reduced. This makes it possible to reduce maintenance costs.

[0028] By adopting the constitution according to the items (1) and (3) of the means for solving the above-mentioned problems, the ion-exchange resin loaded in the water purification system of the makeup water supply system can be used. Since the concentration of phosphoric acid contained in the water to be treated is drastically reduced, the exchange frequency of the ion exchange resin can be reduced. In addition, in the treatment of the phosphoric acid contained in the recovered water, the ion exchange resin loaded in the ion exchange resin device provided with the phosphoric acid removing device does not produce a treatment product in practical use. This makes it possible to further reduce maintenance costs as compared with the case described in the above section.

[Brief description of the drawings]

FIG. 1 is a process flow diagram showing a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention.

FIG. 2 is a process flow diagram showing a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 and 2;

FIG. 3 is a process flow diagram showing a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 and 3;

FIG. 4 is a process flow diagram showing a main part of a conventional phosphoric acid fuel cell power generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Phosphoric acid type fuel cell power generator 2 Phosphoric acid removal device 2a Collected water 5 Make-up water supply system 51 Water tank 61 Heat exchanger 61a Collected water

Claims (3)

[Claims] 1. A phosphoric acid-type fuel cell which uses phosphoric acid as an electrolyte and electrochemically generates electric power using a fuel gas such as hydrogen and an oxidizing gas such as air as a reaction gas. A heat exchanger for recovering moisture from the reacted oxidant gas discharged from the fuel cell after being subjected to the reaction, and at least a recovered water recovered by the heat exchanger is a pure water loaded with an ion exchange resin. Removal of phosphoric acid contained in recovered water in a phosphoric acid type fuel cell power plant equipped with a make-up water supply system for supplying as make-up water to service water used in fuel cells, etc. through a liquefier A phosphoric acid fuel cell power generator, wherein a phosphoric acid removing device is provided in a flow path of recovered water between a heat exchanger and a makeup water supply system. 2. The phosphoric acid fuel cell power generator according to claim 1, wherein the phosphoric acid removing device removes phosphoric acid contained in the recovered water by neutralizing the phosphoric acid with a neutralizing agent. A phosphoric acid fuel cell power generator characterized by the above-mentioned. 3. The phosphoric acid type fuel cell power generator according to claim 1, wherein the phosphoric acid removing device removes phosphoric acid contained in the recovered water with an ion exchange resin. Fuel cell power generator.