JP4655451B2 - Polymer electrolyte fuel cell system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a solid polymer that supplies exhaust gas in a solid polymer fuel cell to an exhaust gas condenser, passes the produced condensed water through a pure water device, and uses the obtained pure water as water for the fuel cell again. The present invention relates to a fuel cell system .
[0002]
[Prior art]
Conventionally, various types of fuel cells have been provided. Of these, phosphoric acid fuel cells have a large apparatus main body and are not suitable for household use. On the other hand, in recent years, a polymer electrolyte fuel cell capable of reducing the size of the apparatus body has been attracting attention for household use.
[0003]
FIG. 4 is a system diagram showing a general configuration of a polymer electrolyte fuel cell device, in which a cell 24 provided with a fuel electrode 22 and an air electrode 23 via an electrolyte 21 and the cell 24 are cooled. The cooling unit 25 is disposed in the fuel cell main body 20.
[0004]
A fuel such as natural gas is introduced into the reformer 30 and reformed into a gas mainly composed of hydrogen by circulating water from a pure water device 40 described later. Combustion air is introduced into the reformer 30 and unreacted fuel (fuel electrode exhaust gas mainly composed of hydrogen) of the fuel electrode 22 is introduced to serve as a heat source for the reforming reaction. The reformed gas is further introduced into the fuel electrode 22 after the carbon monoxide component is transformed by a transformer (not shown). The combustion exhaust gas from the reformer 30 is supplied to the exhaust gas condenser 50.
[0005]
On the other hand, air is introduced into the air electrode 23 from the blower 23B, and the reformed gas introduced into the fuel electrode 22 is oxidized by this air by an electrochemical reaction to generate power. The exhaust gas from the air electrode 23 is supplied to the exhaust gas condenser 50. The fuel electrode exhaust gas may also be supplied to the condenser 50.
[0006]
Condensed water separated by the exhaust gas condenser 50 (hereinafter referred to as “recovered water”) is supplied to the pure water device 40 by the pump 60P through the recovered water tank 60, and the water that has become pure water is supplied to the battery cooling water tank 61. Be sent. The exhaust gas is discharged outside the system.
[0007]
Part of the water in the battery cooling water tank 61 is introduced into the cooling unit 25 of the fuel cell main body 20 as cooling water. The cooling water in the tank 61 circulates in a cooling water circulation system formed between the cooling unit 25 and the battery cooling water tank 61, and a part of the cooling water is supplied as humidified water to the air electrode 23 of the fuel cell body 20, The remainder is fed to the reformer 30 as reforming water.
[0008]
Note that city water is introduced into the recovered water tank 60 or the pure water device 40 as make-up water as necessary.
[0009]
In the polymer electrolyte fuel cell, water is generated when electric power is taken out by an electrochemical reaction. Water is also generated by combustion of the fuel electrode exhaust gas in the reformer, and is contained as water vapor in the combustion exhaust gas. In order to secure the water used for the reforming, these water vapors are condensed and recovered and reused.
[0010]
Since carbon dioxide, Fe, Al, Cu, etc. are dissolved in the recovered water, these are removed by a pure water device when reused. In addition, since the amount of recovered water varies depending on the outside temperature, if the recovered water is insufficient, water is replenished with city water, etc., but dissolved ions, carbon dioxide, etc. are also removed from the city water. It will be necessary.
[0011]
For this reason, the deionized water device 40 treats condensed water and city water as makeup water. As the pure water device 40, a device for producing pure water by an ion exchange method using an ion exchange resin is used.
[0012]
Conventionally, in order to reduce the load on the deionized water device and reduce the amount of ion exchange resin used and the frequency of regeneration, a decarboxylation tower has been installed upstream of the deionized water device to remove the carbonic acid component in the recovered water. (Japanese Patent Laid-Open No. 9-161833).
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-161833 [0014]
[Problems to be solved by the invention]
In a fuel cell, in particular, a polymer electrolyte fuel cell device installed in a general household, it is desired that the entire device is small and simple, and that operation is simple. However, a generally used decarboxylation tower cannot obtain a sufficient decarboxylation efficiency, and gives a large anion load to the pure water apparatus at the subsequent stage. Further, when the decarbonation tower is downsized, the decarbonation performance is lowered, which is a factor that hinders downsizing of the fuel cell device.
[0015]
The present invention solves the above-described conventional problems, supplies exhaust gas in a polymer electrolyte fuel cell to an exhaust gas condenser, passes the generated condensed water through a pure water device, and again returns the obtained pure water to the fuel cell. a polymer electrolyte fuel cell system for use as the water, and also suitable compact for home use, space saving, providing a cost reduction can be solid polymer fuel cell system object To do.
[0016]
[Means for Solving the Problems]
The polymer electrolyte fuel cell system according to claim 1 is obtained by supplying exhaust gas from the polymer electrolyte fuel cell to an exhaust gas condenser and passing the produced condensed water (hereinafter, recovered water) through a pure water device. In the polymer electrolyte fuel cell system using pure water again as water for the fuel cell, a membrane deaeration unit main body having a water passage part on one side of the permeable membrane and a vent part on the other side; An inflow pipe for supplying recovered water to the water flow section, an outflow pipe for discharging degassed treated water from the water flow section, an air supply pipe for supplying gas to the vent section, and exhausting gas from the vent section A polymer electrolyte fuel cell system in which a sweep-type membrane deaerator having an exhaust pipe is installed between the exhaust gas condenser and the pure water device, and in a vent portion of the sweep-type membrane deaerator, It is sent to the cathode or reformer provided in the fuel cell device by an air blower. Characterized in that a means for feeding air to divert part of the air.
[0017]
The solid polymer fuel cell system according to claim 2 is the polymer electrolyte fuel cell system according to claim 1, wherein the sweep-type membrane deaeration device is lower than the exhaust gas condenser so that the recovered water is passed through the water passage portion by a head difference. It is characterized by having been arranged in.
[0018]
The polymer electrolyte fuel cell system according to claim 3 is the polymer electrolyte fuel cell system according to claim 1 or 2, wherein the sweep type membrane deaerator installed between the exhaust gas condenser and the pure water device receives the recovered water from the exhaust gas condenser. It is installed in the upstream of the recovery water tank installed for this purpose.
[0019]
According to a fourth aspect of the present invention, there is provided the polymer electrolyte fuel cell system according to the first or second aspect, wherein the sweep type membrane deaeration device installed between the exhaust gas condenser and the pure water device receives the recovered water from the exhaust gas condenser. For this purpose, it is installed in the downstream of the recovered water tank installed for this purpose, and a pipe for returning a part of the degassed treated water to the recovered water tank is provided.
[0020]
In the polymer electrolyte fuel cell system of the present invention, the load on the pure water device can be reduced by decarboxylating the recovered water of the fuel cell with a sweep type membrane deaerator. With this membrane deaerator, an efficient decarbonation treatment can be performed with a small apparatus without requiring a large apparatus such as a decarbonation tower.
[0021]
In addition, since the sweep type membrane deaerator is adopted, a pressure reducing device required for a normal membrane deaerator is not required, which is convenient for downsizing and noise reduction.
[0022]
In the polymer electrolyte fuel cell system of the present invention, the blower for sweep air of the membrane deaerator can be omitted. That is, in the fuel cell, it is necessary to supply air as an oxygen source to the air electrode, and in order to send fuel air to the reformer, each of the air blowers is provided. By branching a branch pipe to the exhaust side of the blower and communicating with the air supply pipe to the ventilation portion of the membrane deaerator, air as sweep air can be sent to the membrane deaerator. The supply amount of the sweep air can be adjusted by the opening degree of a valve provided in the branch pipe.
[0023]
In the polymer electrolyte fuel cell system according to the second aspect, since the recovered water is supplied to the sweep type membrane deaerator using the water head difference, a pump for supplying the water can be omitted. The water head difference for this water supply depends on the water level of the condensed water accumulated in the lower part of the condenser or, if there is a receiving tank that temporarily receives the condensed water discharged from the condenser, from the water level of this receiving tank. It can be easily obtained by arranging the membrane deaeration device so that the highest part of the treated water outflow pipe of the device is at a low position.
[0024]
In the polymer electrolyte fuel cell system according to claims 3 and 4, the recovered water from the exhaust gas condenser is once received by the recovered water tank, but the recovered water is installed on the upstream (upstream) side of the recovered water tank. Since it is supplied to the recovered water tank as deaerated water through the membrane deaerator, a part of the deaerated water of the membrane deaerator installed on the downstream (downstream) side of the recovered water tank is supplied to the recovered water tank. Since the water is supplied, the recovered water in the recovered water tank is water from which carbonic acid has been removed, and the pH has increased. The water in the recovered water tank is drained as necessary, for example, when it becomes surplus, but since the pH has risen, it can be discharged out of the system without adding a neutralizing agent.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a polymer electrolyte fuel cell system of the present invention will be described below in detail with reference to the drawings.
[0026]
1, 2 and 3 are system diagrams showing embodiments of the polymer electrolyte fuel cell system of the present invention. 1, 2 and 3, members having the same functions as those shown in FIG. 4 are given the same reference numerals.
[0027]
FIG. 1 shows a tank upstream installation method, in which recovered water from an exhaust gas condenser 50 of a polymer electrolyte fuel cell device is introduced into a membrane deaerator 10 through a pipe 51.
[0028]
In the present invention, the membrane deaeration device 10 is divided into a water passage part and a ventilation part by a permeable membrane inside the membrane deaeration part main body, and allows the recovered water to flow through the water passage part and also allows gas to pass through the ventilation part. The sweep-type membrane deaeration device deaerates the gas in the recovered water in the water flow unit through the permeation membrane and diffuses the gas in the ventilation unit.
[0029]
In the membrane deaerator 10, the air fed from the air blower 23 to the air electrode 23 or the reformer 30 provided in the fuel cell device is introduced through the pipe 13, and the recovered water subjected to the decarboxylation treatment. Is recovered in the recovered water tank 60 through the pipe 52. The air introduced into the ventilation part is exhausted from the pipe 14. The water recovered by decarboxylation in this way is drained through the overflow pipe 15 when the pH is improved and the recovered water in the recovered water tank 60 becomes excessive.
[0030]
FIG. 2 shows a tank wake installation system, in which recovered water from the exhaust gas condenser 50 of the polymer electrolyte fuel cell device is recovered in a recovered water tank 60 through a pipe 51.
[0031]
The recovered water sent from the tank by the pump 60 </ b> P is introduced into the membrane deaerator 10 through the inflow pipe 11. In the membrane deaerator 10, the carbon dioxide is decarboxylated by the air introduced through the air supply pipe 13 and supplied to the pure water apparatus 40 through the outflow pipe 12.
[0032]
FIG. 3 shows a case where the recovered water in the decarbonation process in FIG. 2 is excessive and drained, and the pH of the recovered water in the recovered water tank 60 is low, so that it is necessary to meet the drainage standards. 16 shows a method of returning a part of the membrane degassed water to the recovered water tank 60 and improving the pH in the tank.
[0033]
Further, in FIG. 1, in order to pass the condensed water through the membrane deaerator 10 using the water head difference, the membrane deaerator 10 has a higher level than the water level of the condensed water accumulated in the lower part of the condenser 50. The highest position of the deaeration treated water outflow pipe 52 may be low. For this reason, it is preferable that the membrane deaerator 10 is installed at a low position directly under the condenser 50 or in the vicinity thereof.
[0034]
The head difference ΔH for passing condensed water to the membrane deaerator 10 varies depending on the specifications of the membrane deaerator 10 to be used, but is generally about 5 to 40 cm, for example, about 10 cm. Any difference is sufficient.
[0035]
In this way, by degassing the condensed water with the membrane degassing device 10, the load on the pure water device 40 can be reduced. Therefore, the water supply pump of the membrane deaerator 10 becomes unnecessary by passing the condensed water to the membrane deaerator 10 by utilizing the water head difference.
[0036]
Further, by supplying the swept air to the air electrode 23 by diverting it from the air supply blower 23B, no air supply blower is required. For this reason, the incidental facilities of the membrane deaeration device 10 are greatly reduced, and the overall size of the device can be reduced, space saving, and cost reduction can be achieved.
[0037]
The degassed water of the membrane deaerator 10 is processed by the pure water device 40 through the recovered water tank 60 and then temporarily stored in the battery cooling water tank 61. As in the prior art, the cooling unit of the fuel cell main body 20 is stored. 25 as cooling water, as humidified water for the air electrode 23, and further as reforming water for the reformer 30.
[0038]
The configuration of the deionized water device 40 is not particularly limited, and generally, a device equipped with an ion exchange device, an electric demineralizer, or the like is used. In any case, the dewatering device 10 uses a deaerator. Due to the air treatment, the load of the pure water device 40 is reduced, and good treated water can be stably obtained over a long period of time.
[0039]
The water treatment device for a polymer electrolyte fuel cell shown in FIGS. 1, 2 and 3 shows an example of an embodiment of the polymer electrolyte fuel cell device of the present invention, and the present invention exceeds the gist thereof. As long as it is not, it is not limited to what is illustrated.
[0040]
In FIG. 1, air is divided from the exhaust side of the air supply blower 23B to the air electrode 23 of the fuel cell body 20 and supplied to the ventilation portion of the membrane degassing device 10, but as described above, the fuel cell device. Since an air supply blower (not shown) for introducing combustion air into the reformer 30 is provided, air is separated from the exhaust side of the air supply blower to the reformer 30. The air may be supplied to the ventilation part of the membrane deaeration device.
[0041]
Further, in FIG. 1, the recovered water from the condenser 50 is directly passed through the membrane deaerator 10 for deaeration treatment, but after the recovered water from the condenser is once received in the receiving tank, the membrane deaeration is performed. It can also be deaerated by passing water through the apparatus. In this case, what is necessary is just to arrange | position so that the highest part of the deaeration process water discharge piping of a membrane deaeration apparatus may become a low position rather than the water level of this receiving tank.
[0042]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0043]
Example 1
Degassing membrane with a diameter of 0.75 inches and length of 5 inches (122.5 mm) at a flow rate of 1.2 L / h using carbon dioxide gas concentration 150 mg / L of the exhaust gas condensed water of a polymer electrolyte fuel cell as raw water Was passed through a sweep-type membrane deaerator having a flow rate of 7.2 L / h, and the carbon dioxide concentration of the resulting degassed water was 6 mg / L. Met.
[0044]
When installed with a head difference of ΔH = 10 cm so that the highest position of the deaeration treated water outflow pipe of this membrane deaerator is located 15 cm below the water level of the fuel cell condenser, The condensed water could be passed from the condenser without the need for pressurization. In addition, since the allowable air supply amount of the air supply blower to the air electrode of the fuel cell body is 4000 L / h, while the air amount required at the air electrode is 3280 L / h, a membrane for degassing The supply of 7.2 L / h to the deaerator was able to be performed without any trouble.
[0045]
As described above, the condensed water of the condenser was supplied to the membrane deaerator using the water head difference, and the membrane was deaerated by supplying air by dividing the air from the blower for supplying air to the air electrode. However, it was possible to stably deaerate the condensed water having a carbon dioxide concentration of 150 mg / L to obtain degassed water having a carbon dioxide concentration of 1 to 6 mg / L.
[0046]
Comparative Example 1
Using carbon dioxide gas concentration 150 mg / L, the exhaust gas condensate of the polymer electrolyte fuel cell as raw water, it was treated with a decarbonation tower with a straight body length of 190 mm at an inflow air amount of 1050 L / h and a raw water flow rate of 1.2 L / h. However, the treated water carbon dioxide concentration was 25 mg / L. Moreover, when the inflow air amount was dropped to 800 L / h, the treated water carbon dioxide concentration was 50 mg / L. Further, when the amount of air allowed by the air electrode blower of the fuel cell main body was 4000 L / h and the raw water amount was 1.2 L / h, the carbon dioxide concentration was 10 mg / L. The length of the straight body portion is necessary for a 800 mm decarboxylation tower, and it has been confirmed that the fuel cell device is enlarged.
[0047]
【The invention's effect】
As described above in detail, according to the polymer electrolyte fuel cell system of the present invention, the concentration of carbon dioxide contained in the recovered water from the exhaust gas condenser of the fuel cell can be reduced by about 95%. It is possible to greatly reduce the load of the pure water apparatus provided in
[0048]
In addition, by supplying air necessary for the decarbonation treatment from an air electrode provided in the fuel cell device or an air supply blower to the reformer, a dedicated air supply blower can be omitted. Miniaturization, space saving, and cost reduction can be achieved.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a polymer electrolyte fuel cell system adopting a tank upstream flow installation method in which a sweep type membrane deaeration device is installed upstream of a recovery water tank in the present invention.
FIG. 2 is a system diagram showing an embodiment of a polymer electrolyte fuel cell system adopting a tank wake installation method in which a sweep type membrane deaeration device is installed in the wake of a recovered water tank in the present invention.
[Fig. 3] A water treatment device for a polymer electrolyte fuel cell adopting a tank wake installation method in which a sweep type membrane deaeration device is installed in the wake of a recovered water tank, for the purpose of improving the pH of recovered water in the tank. It is a systematic diagram to which a return line is added.
FIG. 4 is a system diagram showing a general configuration of a polymer electrolyte fuel cell device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Membrane deaerator 11 Membrane deaerator inflow pipe 12 Membrane deaerator outflow pipe 13 Membrane deaerator inlet sweep air supply pipe 14 Membrane deaerator outlet sweep air exhaust pipe 15 Recovered water tank overflow pipe 16 Deaerated treated water Return piping 20 Fuel cell body 21 Electrolyte 22 Fuel electrode 23 Air electrode 23B Air electrode blower 24 Cell 25 Cooling unit 30 Reformer 40 Pure water device 50 Exhaust gas condenser 51 Exhaust gas condenser outlet / recovery water piping 52 Recovered water in recovered water tank Piping (piping for degassing water washing)
60 recovered water tank 60P water pump 61 battery cooling water tank

Claims (4)

Solids that supply exhaust gas from a polymer electrolyte fuel cell to an exhaust gas condenser, pass the generated condensed water (hereinafter referred to as recovered water) through a pure water device, and use the obtained pure water again as water for the fuel cell In the polymer fuel cell system ,
A membrane deaeration unit body having a water flow part on one side of the permeable membrane and a ventilation part on the other side, an inflow pipe for supplying recovered water to the water flow part, and deaeration from the water flow part A sweep type membrane deaerator having an outflow pipe for discharging treated water, an air supply pipe for supplying gas to the ventilation section, and an exhaust pipe for discharging gas from the ventilation section, from the exhaust gas condenser to a pure water apparatus A polymer electrolyte fuel cell system installed between
Means for diverting a part of the air supplied by the air supply blower to the air electrode or the reformer provided in the fuel cell device is provided in the ventilation part of the sweep type membrane deaeration device. A polymer electrolyte fuel cell system . 2. The solid polymer according to claim 1, wherein the sweep-type membrane deaerator is disposed at a lower position than the exhaust gas condenser so that the recovered water is passed through the water passage portion by a head difference. Fuel cell system . The sweep flow membrane deaeration device installed between the exhaust gas condenser and the deionized water device according to claim 1 or 2, wherein the sweep type membrane deaeration device is installed upstream of the recovered water tank installed to receive the recovered water from the exhaust gas condenser. A polymer electrolyte fuel cell system installed in The wake of the recovery water tank installed in order to receive the recovered water from the exhaust gas condenser in the sweep type membrane deaeration device installed between the exhaust gas condenser and the pure water device according to claim 1 or 2. The polymer electrolyte fuel cell system is provided with a pipe for returning a part of the degassed treated water to the recovered water tank.

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