JP2003157869A - Water treating device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an installation by stabilizing a resupply water amount and a resupply water temperature of a fuel cell regardless a water temperature fluctuation at season in a water treating device for the fuel cell. SOLUTION: In this water treating device for the fuel cell, after raw water in a raw water tank 1 is subjected to deionizing treatment in an RO membrane separation device 2 and an electric deionizing device 3, the water is supplied to the fuel cell 4, and before the raw water is subjected to membrane treatment, it is warmed by utilizing exhaust heat of the fuel cell 4. For example, air at a high temperature generated in the fuel cell 4 is sent to the raw water tank 1 by blower B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment device for supplying water to a fuel cell, and more particularly to a water treatment device for supplying raw water to a fuel cell after purifying the raw water by a purification means having a membrane treatment means. The present invention relates to a fuel cell water treatment device that realizes stabilization of the amount of supplied water with respect to seasonal fluctuations in the water temperature.

[0002]

2. Description of the Related Art A fuel cell is a power generation system that directly takes out electricity by electrochemically reacting hydrogen and oxygen, has high power generation efficiency regardless of power generation capacity, and emits a small amount of nitrogen oxides.

There are various types of fuel cells such as alkaline type, solid polymer type, phosphoric acid type, molten carbonate type, and solid electrolyte type, depending on the type of electrolyte. It is necessary to replenish water as steam water for the reformer, and as cooling water for the fuel cell body and solid polymer in phosphoric acid fuel cells. Therefore, city water is purified and supplied to the fuel cell. Water treatment equipment is attached.

FIG. 5 is a system diagram showing an example of a fuel cell and its water treatment device. City water is introduced into the reverse osmosis (RO) membrane separation device 2 from the raw water tank 1 of the water treatment device by the pump P ₁ to be deionized, and further deionized by the electric deionization device 3, and then the fuel cell. 4 is fed to the pure water tank 4A.

The fuel cell system shown in FIG. 5 uses the exhaust heat of the fuel cell 4 to supply hot water to the bath, so that the heat generated by the fuel cell body 4B heats the city water in the hot water storage tank 5. Is configured. The hot water in this hot water storage tank 5 is pump P
It is sent to the bath at ₂ .

In this water treatment device, the concentrated water of the RO membrane separation device 2 is discharged to the outside of the system, but the concentrated water of the electric deionization device 3 is returned to the raw water tank 1 and circulated.

[0007]

In a membrane separation device such as an RO membrane separation device, the amount of produced water is greatly affected by the temperature of the raw water introduced, and when the temperature of the raw water decreases, the amount of produced water decreases significantly.

That is, the viscosity of water changes depending on the water temperature, and when the water temperature is low, the viscosity remarkably increases. For example, the viscosity of water at a water temperature of 20 ° C. is 1.0020 cp, while the water temperature of 5 ° C.
With water at 0 ° C, the viscosity increases to 1.25 cp by about 25%. Then, the low-temperature water whose viscosity becomes high hardly passes through the membrane surface, so that the amount of water produced by the membrane separation apparatus is significantly reduced.

Therefore, in the conventional fuel cell water treatment device, the amount of water produced by the RO membrane separator is lower in the winter when the water temperature is low than in the summer when the water temperature is high. Therefore, in the winter when the amount of produced water decreases, a sufficient amount of water is supplied to the water treatment device including the RO membrane separation device so that the amount of supplementary water to the fuel cell does not become insufficient.

[0010] Specifically, assuming that the water temperature in winter is 7 ° C and the water temperature in summer is 22 ° C, the facility capacity designed at the water temperature in summer is expected in consideration of the decrease in the amount of water produced by the RO membrane separator in winter. On the other hand, the equipment has been enlarged so as to have a margin of about 45%.

Further, the water temperature of the makeup water of the fuel cell fluctuates due to the seasonal fluctuation of the water temperature, so that the operation of the fuel cell may become unstable.

The present invention solves the above-mentioned conventional problems, and in a fuel cell water treatment apparatus, by stabilizing the amount of water supplied and the temperature of the water supplied to the fuel cell regardless of seasonal fluctuations in water temperature, the equipment can be made smaller. An object of the present invention is to provide a water treatment device for a fuel cell, which aims at achieving stable operation of the fuel cell.

[0013]

A water treatment apparatus for a fuel cell according to the present invention is a water treatment apparatus for supplying raw water to a fuel cell after purifying the raw water by a purifying means having a membrane treatment means. It is characterized by having a heating means for heating by utilizing exhaust heat of the fuel cell.

In the fuel cell water treatment device of the present invention, the exhaust heat of the fuel cell is used to heat the raw water for membrane treatment of the water treatment device, thereby preventing a decrease in the amount of water produced due to a decrease in the water temperature in winter. Therefore, it is possible to always secure a high production water amount. Therefore, it becomes unnecessary to excessively set the facility capacity of the water treatment device such as the RO membrane separation device, and the facility can be downsized. Further, by stabilizing the water temperature of the raw water for membrane treatment, the water temperature of the makeup water of the fuel cell becomes stable, and the fuel cell can be operated stably.

In the present invention, since the exhaust heat of the fuel cell is used to heat the raw water for membrane treatment, it is not necessary to add large-scale equipment for heating, and the overall efficiency of the fuel cell is increased. Can be increased and is economical.

In the present invention, the following are preferable as the heating means. A heat exchanger installed in the box of the fuel cell and a pipe for introducing raw water into the heat exchanger for heat exchange and then introducing it into the purifying means; Delivering air in the box of the fuel cell An air delivery means and a heat exchange means for exchanging heat between the air delivered by the air delivery means and the raw water. Mixing part of the warm water in the hot water tank with raw water.

Such a heating means preferably has a heating amount adjusting means for heating the raw water to a temperature not higher than the heat resistant temperature of the membrane.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 4 are system diagrams each showing an embodiment of the present invention. The fuel cell water treatment device of FIGS. 1 to 4 has the same configuration as that of the fuel cell water treatment device shown in FIG. 5, except that a heating means for water introduced into the RO membrane separation device 2 is provided. In FIGS. 1 to 3, members having the same functions as those shown in FIG. 5 are designated by the same reference numerals.

In any of FIGS. 1 to 4, the city water in the raw water tank 1 is introduced into the reverse osmosis (RO) membrane separation device 2 by the pump P ₁ and is deionized, and further the electric deionization device 3 is used.
After being deionized in, the pure water tank 4A of the fuel cell 4
Sent to. The city water in the hot water storage tank 5 is heated by the heat generated by the fuel cell body 4B. The hot water in the hot water storage tank 5 is sent to the bath by the pump P ₂ .

In the fuel cell water treatment apparatus of FIG. 1, a blower (air delivery means) B for discharging the high temperature air in the fuel cell 4 is provided in the fuel cell 4, and the high temperature air is supplied to the raw water tank 1. To heat the raw water in the raw water tank 1 by aeration. In this water treatment device, a thermometer T is provided in the pipe on the inlet side of the RO membrane separation device 2, and a blower B of the blower B is blown based on the measurement result of the thermometer T by a control device (inverter circuit or the like) not shown. Is adjusted to adjust the amount of air sent to the raw water tank 1 to control the water temperature of the raw water for membrane treatment to a suitable temperature described later.

In this way, when the blower B is provided and the raw water is heated by the high temperature air in the fuel cell 4, a heat exchanger is provided in the pipe on the inlet side of the RO membrane separation device 2, and this heat exchanger is used. In the above, the raw water for membrane treatment may be heated by exchanging heat between the raw water introduced into the RO membrane separation device 2 and the high temperature air. In this case, the water temperature is not adjusted by adjusting the air flow rate of the blower B, and the bypass pipe for supplying raw water to the RO membrane separation device 2 after introducing the raw water into the heat exchanger is connected to the RO membrane separation device from the raw water tank 1. Installed in the pipe for supplying raw water to 2,
It may be carried out by adjusting the amount of raw water introduced into the heat exchanger and heated.

In the fuel cell water treatment apparatus shown in FIG. 2, the hot water storage tank 5 is used as a heat exchanger, and a bypass pipe is provided in the pipe for feeding raw water from the raw water tank 1 to the RO membrane separation device 2. Hot water storage tank 5 for at least a part of raw water for membrane treatment
And is heated by the hot water in the hot water storage tank 5, and then introduced into the RO membrane separation device 2.

Also in this water treatment device, a thermometer T is provided in the pipe on the inlet side of the RO membrane separation device 2, and a control device (PID controller or the like) (not shown) is used to measure the temperature based on the thermometer T. Adjust the opening of the valve V to adjust the hot water storage tank 5
By controlling the amount of raw water that is fed to and heated, the water temperature of the raw water for membrane treatment is controlled to a suitable temperature described below.

In the fuel cell water treatment device shown in FIG. 3, a heat transfer tube for heating the hot water storage tank 5 in the fuel cell 4 is used as a heat exchanger, and raw water is fed from the raw water tank 1 to the RO membrane separation device 2. A bypass pipe is provided in the pipe, and at least a part of the raw water for membrane treatment is heat-exchanged and heated in the heat transfer pipe of the fuel cell 4 in the bypass pipe and then introduced into the RO membrane separation device 2. Is.

Also in this water treatment device, a thermometer T is provided in the pipe on the inlet side of the RO membrane separation device 2, and a control device (PID controller or the like) (not shown) determines the temperature based on the measurement result of the thermometer T. By adjusting the opening degree of the valve V and adjusting the amount of raw water that is fed into the fuel cell 4 and heated.
The water temperature of the raw water for membrane treatment is controlled to a suitable temperature described later.

In the fuel cell water treatment apparatus shown in FIG. 4, hot water in the hot water storage tank 5 is introduced by a pump P ₃ into a pipe for supplying raw water from the raw water tank 1 to the RO membrane separation device 2.

Even in this water treatment apparatus, the temperature of the raw water for membrane treatment is controlled by adjusting the discharge amount of the pump P ₃ based on the measurement result of the thermometer T and adjusting the amount of hot water introduced into the raw water. Is controlled to a suitable temperature described later.

In the water treatment device shown in FIGS. 2, 3 and 4, the flow rate adjusting valve V directly feeds the raw water from the raw water tank 1.
You may provide in the piping which supplies water to the membrane separation apparatus 2.

In the present invention, the heating temperature of the raw water for membrane treatment must be lower than the heat resistant temperature of the membrane. This heat-resistant temperature varies depending on the material of the film, but is generally about 40 ° C.
Therefore, the heating temperature of the raw water for membrane treatment is preferably 40 ° C. or lower, and particularly preferably 35 ° C. or lower. However, if the heating temperature is too low, it is difficult to increase the amount of water produced by heating, so it is preferably set to 20 ° C. or higher. Further, when the water temperature of the raw water for membrane treatment is 30 to 35 ° C., the ion removal rate is slightly reduced, and
In the present invention, the heating temperature of the raw water to be membrane-treated is preferably about 20 to 30 ° C., since bacteria are easily generated.

The water treatment apparatus shown in FIGS.
Although the membrane separation device 2 and the electric deionization device 3 are combined, the water treatment device of the present invention is not limited as long as it has a membrane separation device, and is not limited to those shown in FIGS. Not a thing. The present invention can be applied to, for example, a fuel cell water treatment device having the following configuration. RO membrane separator → Mixed bed type ion exchange resin tower RO membrane separator → RO membrane separator Nano filtration (loose RO) membrane separator → Electrodeionization device Nano filtration membrane separator → Mixed bed ion exchange resin tower

Further, the fuel cell 4 of the fuel cell water treatment apparatus shown in FIGS. 1 to 4 has a hot water storage tank 5 utilizing exhaust heat, but in the present invention, the structure of the fuel cell is not particularly limited. Alternatively, the hot water storage tank 5 may be omitted.

Further, in FIGS. 1 to 4, the raw water is heated between the raw water tank 1 or the raw water tank 1 and the RO membrane separation device 2.
The raw water may be heated before the raw water tank 1 or may be heated before being branched to the hot water storage tank 5. However, in order to efficiently heat the raw water for membrane treatment, it is preferable to heat the raw water after branching to the hot water storage tank 5, and the raw water is heated before the raw water tank 1 or in the raw water tank 1. If you want to warm
In some cases, it may be necessary to provide a heat insulating means for the raw water tank 1.

[0034]

As described in detail above, according to the present invention, in a fuel cell water treatment device, the amount of replenishment water and the replenishment water temperature of the fuel cell are stabilized regardless of the seasonal variation of the water temperature, thereby downsizing the equipment. And stable operation becomes possible.

Moreover, in the present invention, since the exhaust heat of the fuel cell is effectively used to heat the raw water, it is not necessary to newly add a large-scale facility for this heating, and the total fuel cell The efficiency can be improved and the economy is excellent.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a fuel cell water treatment device of the present invention.

FIG. 2 is a system diagram showing another embodiment of the fuel cell water treatment device of the present invention.

FIG. 3 is a system diagram showing a different embodiment of the fuel cell water treatment device of the present invention.

FIG. 4 is a system diagram showing another embodiment of the fuel cell water treatment device of the present invention.

FIG. 5 is a system diagram showing a conventional fuel cell water treatment device.

[Explanation of symbols]

1 raw water tank 2 RO membrane separator 3 Electric deionization equipment 4 fuel cells 5 hot water storage tank

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01D 61/58 B01D 61/58 C02F 1/469 H01M 8/00 Z H01M 8/00 C02F 1/46 103 F Term (reference) 4D006 GA03 GA04 GA17 KA01 KA52 KA57 KA71 KB11 KB30 KE16P KE16Q PA01 PB06 PC80 4D061 DA03 DB13 EA09 EB04 EB37 EB39 GA09 GC05 5H027 AA02 DD06 KK48

Claims (5)

[Claims] 1. A water treatment apparatus for supplying raw water to a fuel cell after purifying the raw water by a purifying means having a membrane treatment means, wherein the raw water before the membrane treatment is heated by utilizing exhaust heat of the fuel cell. A water treatment device for a fuel cell, comprising: 2. The heating means according to claim 1, wherein the heating means is a heat exchanger installed in the box body of the fuel cell, and raw water is introduced into the heat exchanger to exchange heat with the heat exchanger. A water treatment device for a fuel cell, comprising: a pipe for introducing the water treatment device. 3. The heating means according to claim 1, wherein the heating means sends out air in the box of the fuel cell, and heat exchange means for exchanging heat between the air sent out by the air sending means and raw water. A water treatment device for a fuel cell, comprising: 4. The mixing means according to claim 1, further comprising a hot water storage tank for storing hot water heated by waste heat of the fuel cell, wherein the heating means mixes a part of the hot water in the hot water storage tank with raw water. A water treatment device for a fuel cell, wherein: 5. The fuel cell water treatment device according to claim 1, wherein the heating means has heating control means for heating the raw water to a temperature equal to or lower than the heat resistant temperature of the membrane. .