JP2000208157A - Fuel cell operation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a conductive ion concentration in cooling water low at any time by removing conductive ions in the cooling water with an ion removing filter provided in sub-piping regardless of an operation condition of a fuel cell. SOLUTION: In this system, the cooling water of pure water is made to flow through a solid polymer fuel cell 1 via main piping 3 and is made to flow through a heat exchanger 5 to be cooled, while the cooling water of pure water stored in a main tank 2 is simultaneously is made to flow through sub-piping 11 to remove conductive ions in the cooling water with an ion removing filter 6 provided in the sub-piping 11, so that a conductive ion concentration in the cooling water is kept not more than a prescribed value at any time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell operation system for operating a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art In recent years, fuel cell technology that enables clean exhaust and high-efficiency energy efficiency has been focused on environmental problems, in particular, the problems of air pollution caused by automobile exhaust gas and global warming caused by carbon dioxide. Have been.

[0003] A fuel cell is an energy conversion system in which hydrogen or hydrogen-rich reformed gas as the fuel and air are supplied to cause an electrochemical reaction to convert chemical energy into energy. And among them,
2. Description of the Related Art A solid polymer electrolyte fuel cell having a high output density has attracted attention as a power source for a mobile body such as an automobile.

In such a polymer electrolyte fuel cell, it is necessary to supply cooling water in order to maintain a normal operating temperature of about 80 ° C., and it is necessary to supply water to the polymer electrolyte ion exchange membrane in the fuel cell. It is necessary to supply high purity pure water for maintenance. Therefore, conventionally, by employing a driving system having the configuration shown in FIG. 3, by supplying cooled pure water to the polymer electrolyte fuel cell, the generated power is taken out while satisfying both needs. Like that.

[0005] The fuel cell operation system for the conventional polymer electrolyte fuel cell shown in FIG. 3 has the following configuration. Pure water cooling water is supplied to the polymer electrolyte fuel cell 1 by the main pump 4 from the main tank 2 through the main pipe 3, and the pure water cooling water passing through the fuel cell 1 is supplied to a heat exchanger 5 such as a radiator. To form a main circulation system for returning to the main tank 2 after cooling.

[0006] Then, the conductive ions dissolve into the pure water cooling water from the heat exchanger 5 for cooling the cooling water, and when the conductive ions increase, a short circuit occurs in the fuel cell 1 and the power generation amount decreases. Therefore, it is necessary to remove the conductive ions from the cooling water. For this reason, conventionally, an ion removal filter 6 for removing the conductive ions dissolved from the heat exchanger 5 is provided on the main pipe 3. Provided.

Further, by installing the ion removal filter 6 on the main pipe 3, when the fuel cell 1 requires a large amount of cooling water under a high load operation, the pressure loss of the cooling water in the ion removal filter 6 is reduced. In order to compensate for this, a bypass pipe 7 is provided to compensate for this. In addition, if a small amount of cooling water is used so that the pressure loss of the filter 6 does not need to be considered in this low load operation, the ion removal should be performed. Although the pure water cooling water can be positively passed through the ion removal filter 6 in order to positively advance, it is necessary to cut off the flow of the cooling water to the bypass pipe 7,
A flow control valve 8 is provided on the bypass pipe 7.

[0008]

However, in such a conventional fuel cell operation system, the flow control valve 8 provided on the bypass pipe must be controlled in accordance with the operation of the fuel cell, and the control is complicated. However, if the duration of the high-load operation is prolonged, there is a problem that the ion cannot be sufficiently removed.

The present invention has been made in order to solve such a conventional problem. By providing a cooling water flow path for removing ions independently of a main pipe, a bypass which has been conventionally required is provided. It is an object of the present invention to provide a fuel cell operation system that eliminates the need for valve control for controlling the flow rate of piping and that can always maintain the ion concentration in pure water cooling water at a predetermined value or less.

[0010] The present invention also provides a fuel cell operation system capable of controlling the flow rate of cooling water passing through an ion removal filter in accordance with the ion concentration in the cooling water and stably maintaining an ion concentration of a predetermined value or less. The purpose is to:

[0011]

According to the first aspect of the present invention, pure water cooling water circulated for temperature control of a fuel cell and for humidification of a solid polymer ion exchange membrane in the fuel cell is supplied from a main tank to a main pump. After supplying pure water cooling water to the polymer electrolyte fuel cell and cooling the pure water cooling water passing through the fuel cell by the heat exchanger, the fuel cell operation system returns to the main tank. Separately, a sub-pipe and a sub-pump for circulating the pure water cooling water are provided, and an ion removal filter for removing conductive ions dissolved in the pure water cooling water is provided on the sub pipe. It is.

In the fuel cell operation system according to the first aspect of the present invention, pure water cooling water flows through the main pipe flow path to the polymer electrolyte fuel cell and is cooled through the heat exchanger. The pure water cooling water stored in the main tank is passed through the sub-pipe, and the conductive ions in the cooling water are removed by an ion removal filter provided on the sub-pipe. Is always kept below a predetermined value.

[0013] Thereby, pure water cooling water at a required flow rate can be freely passed through the main pipe flow path according to the high load and the low load of the fuel cell. The ion concentration can also be stably maintained at a predetermined value or less.

According to a second aspect of the present invention, in the fuel cell operation system of the first aspect, the conductivity of the pure water cooling water, which is provided at an arbitrary position along a pipe through which the pure water cooling water flows, is further reduced. A conductivity meter for measuring, and sub-pump control means for controlling the operation of the sub-pump so that the conductivity detected by the conductivity meter becomes a predetermined value or less, and the conductivity meter detects the conductivity. If the conductive ion concentration of the pure water cooling water increases, the flow rate of the cooling water flowing through the sub-pipe flow path is increased to enhance the ion removing action, so that the ion concentration is always maintained at a predetermined value or less. Energy saving operation is achieved without constantly flowing as much cooling water as necessary into the sub-pipe flow path.

[0015]

As described above, according to the first aspect of the present invention,
The pure water cooling water is passed through the main pipe flow path to the polymer electrolyte fuel cell and cooled through the heat exchanger, and at the same time, the pure water cooling water stored in the main tank is sent to the sub pipe. It is circulated, and the conductive ion in the cooling water is removed by the ion removal filter provided on this sub-pipe. While allowing the water cooling water to flow freely, the concentration of the conductive ions in the cooling water can be maintained at a predetermined value or less.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the cooling water flowing through the sub-pipe flow path if the conductive ion concentration of the pure water cooling water detected by the conductivity meter increases. Since the ion removal action is enhanced by increasing the flow rate and the ion concentration is always maintained at a predetermined value or less, unnecessary cooling water does not always flow to the sub-pipe flow path, and energy saving operation can be achieved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration of the first embodiment of the present invention. The configuration of the main piping system of the fuel cell operation system according to the first embodiment is the same as that of the conventional example shown in FIG. Pump 4
, A pure water cooling water that has passed through the fuel cell 1 is cooled by a heat exchanger 5 such as a radiator, and then returned to the main tank 2.

As a feature of the present invention, a sub-pipe 11 is connected to the main tank 2 in parallel with the main pipe 3, and a sub-pump 12 is provided on the sub-pipe 11,
Further, an ion exchange filter 6 is provided. By operating the sub-pump 12, pure water cooling water flows through the sub-pipe 11, and the ion removal filter 6 constantly removes conductive ions dissolved in the pure water cooling water. The purity of the cooling water stored in the tank is kept high.

In the fuel cell operation system according to the first embodiment, the pure water cooling water stored in the main tank 2 is supplied to the fuel cell 1 by the main piping system to cause the fuel cell 1 to generate electric power. After passing the cooling water passing through the heat exchanger 5 to remove heat, the cooling water is returned to the main tank 2.
In parallel with this, the pure water cooling water stored in the main tank 2 is caused to flow also through the sub-pipe 11 by the operation of the sub-pump 12, and is dissolved out of the heat exchanger 5 into the cooling water by the ion removal filter 6. It removes and purifies conductive ions and maintains the purity of pure water cooling water at a high level.

According to the first embodiment, the ion removal filter 6 is connected to the sub pipe 1 independent of the main pipe 3.
By providing the cooling water on the fuel cell 1, even when the amount of pure water cooling water used varies depending on the operating conditions of the fuel cell 1, the pressure loss of the ion removal filter does not affect the pure water cooling water at all.

For this reason, it is possible to adopt an operation method in which the flow rate of the cooling water flowing through the sub-pipe 11 is set to the minimum necessary, and the cooling water is flowed continuously to continuously remove the conductive ions. Thus, a small pump can be used as the sub-pump 12, and the power consumption can be reduced.

In addition, since the pressure loss of the ion removing filter 6 does not affect the operation of the fuel cell 1, a filter emphasizing the ion removing ability can be used, thereby improving the ion removing efficiency. As a result, the concentration of the conductive ions dissolved in the pure water flowing through the main pipe can be always kept low.

Further, since there is no ion removal filter on the main pipe 3, the layout of the main pipe system has a high degree of freedom.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. The second embodiment is different from the first embodiment shown in FIG. 1 in that a conductivity meter 13 for measuring the concentration of conductive ions in the cooling water is provided on the main pipe 3 or in the main tank 2. The sub-pump 12 on the sub-pipe 11 is activated for a fixed time when the conductivity measured by the conductivity meter 13 exceeds a predetermined value.

In the fuel cell operation system according to the second embodiment, the pure water cooling water stored in the main tank 2 is supplied to the main pipe by operating the main pump 4 as in the first embodiment. The fuel is supplied to the fuel cell 1 through a heat exchanger 3 and heat is removed through a heat exchanger 5 after power generation. In parallel with this, the pure water cooling water stored in the main tank 2 is passed through the sub-pipe 11 by the sub-pump 12, and the conductive water dissolved in the cooling water by the ion removal filter 6 on the sub-pipe 11. The ions are removed, and the purified cooling water is returned to the main tank 2.

The circulation operation of the cooling water on the sub-pipe flow path is performed as follows. The conductivity meter 13 constantly monitors the concentration of conductive ions dissolved in the cooling water in the main tank 2 or the cooling water flowing through the main pipe 3. When the ion concentration exceeds a predetermined value, the pump controller 14 activates the sub-pump 12 for a certain period of time to supply the cooling water in the main tank 2 to the sub-pipe 1
1 and the conductive ions are removed by the ion removing filter 6 during the circulation, thereby improving the purity of the cooling water.

Here, if the ion concentration does not fall below a predetermined value even when the sub-pump 12 is started for a fixed time and the conductive ion in the cooling water is removed by the ion removing filter 6, the pump controller 14 is further fixed. The sub-pump 12 is repeatedly operated for each time, and the operation is stopped when the ion concentration falls below a predetermined value.

As described above, in the second embodiment, as in the first embodiment, the ions in the cooling water are removed by the ion removal provided on the sub pipe 11 regardless of the operating conditions of the fuel cell 1. It can be removed by the filter 6 and the concentration of the conductive ions in the cooling water can always be kept at a low value. Further, since the sub-pump 12 is operated only when the ion concentration in the cooling water exceeds a predetermined value, the operation efficiency is good and the energy-saving operation can be performed.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a system diagram showing a configuration of a second embodiment of the present invention.

FIG. 3 is a system diagram showing a configuration of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Main tank 3 Main piping 4 Main pump 5 Heat exchanger 6 Ion removal filter 11 Sub piping 12 Sub pump 13 Conductivity meter 14 Pump controller

Claims (2)

[Claims] 1. Pure water cooling water circulated for temperature control of a fuel cell and for humidification of a solid polymer ion exchange membrane in the fuel cell is supplied from a main tank to the polymer electrolyte fuel cell by a main pump. In a fuel cell operation system in which pure water cooling water that has passed through a battery is cooled by a heat exchanger and then returned to a main tank, for the main tank, separately from the main pipe,
A sub-pipe and a sub-pump for circulating the pure water cooling water are provided, and an ion removal filter for removing conductive ions dissolved in the pure water cooling water is provided on the sub pipe. Fuel cell operation system. 2. A conductivity meter provided at an arbitrary position along a pipe through which the pure water cooling water flows to measure the conductivity of the pure water cooling water, and a conductivity detected by the conductivity meter. 2. The fuel cell operation system according to claim 1, further comprising: sub-pump control means for controlling the operation of the sub-pump such that the rate becomes equal to or less than a predetermined value.