JPH0689732A - Fuel cell - Google Patents

Abstract

PURPOSE:To make safe operation of power generating continuously with a fuel cell even when it is not possible to perform the heat exhaust process with its exhaust heat processing device. CONSTITUTION:The output of a fuel cell is supplied through a cell output control device 12. If the exhaust heat collecting heat-exchanger 7 is not capable of exhausting the heat emitted by the body 1 of the fuel cell to the outside of the cell coolant system, a control device 5 measures the pressure in a stream separator 3 using a pressure sensor 6, controls the cell output control device 12 so that the pressure becomes constant, and decreases the amount of power generation of the fuel cell. This discreasing causes the heat emission amount at power generating to balance with the natural heat radiating, etc., makes constant the reacting temp. of the fuel cell, and permits continued operation of power generation while the heat exhaust process to outside the cell coolant system is no more needed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell in which power generation operation can be safely continued even when exhaust heat treatment equipment for cell cooling water cannot be exhaust heat treated due to a failure or the like.

[0002]

2. Description of the Related Art An example of a conventional fuel cell is shown in FIG. In the figure, 1 is a fuel cell main body, 2 is a reformer, 3 is a steam separator, 4 is a safety valve, 6 is a pressure sensor, 7 is an exhaust heat recovery heat exchanger, 8 is a heat recovery control valve, and 11 is a fuel. An inverter for converting the DC electric output of the battery into an AC output, 14 is a water treatment device, 15 is an ejector, 16 is a battery cooling water circulation pump, 17 is a heat recovery amount adjusting device, and 17a is its signal line.

In the fuel cell main body 1, hydrogen in the reformed gas obtained by reforming the fuel in the reformer 2 and oxygen in the air perform a reverse reaction of electrolysis of water to generate electricity. In the phosphoric acid fuel cell, the power generation reaction at this time is carried out at a temperature of about 200 [° C.], and heat is generated. Therefore, in order to keep the temperature of the fuel cell body 1 constant at about 200 [° C.] and to dissipate the generated heat to the outside of the fuel cell body 1, the cell cooling water is circulated in the fuel cell body 1 by the cell cooling water circulation pump 16. I'm running into. The heat generated by the fuel cell body 1 is recovered by converting high-temperature water in the cell cooling water system into steam. A part of the recovered heat is mixed with fuel from the steam separator 3 through the ejector 15 and sent to the reformer 2 in order to carry out the reforming reaction as steam. Further, in order to prevent the concentration of impurities in the battery cooling water by discharging the steam to the reformer 2, a part of the battery cooling water is blown down to the water treatment device 14. A part of the recovered heat is discharged together with the blowdown water. The remaining heat is condensed in the exhaust heat recovery heat exchanger 7 and radiated to the outside of the battery cooling water system by the secondary cooling water. The amount of heat recovered in the exhaust heat recovery heat exchanger 7 is controlled by operating the heat recovery amount control valve 8. That is, the heat recovery amount control valve 8 is
The pressure of the steam separator 3 is detected by the pressure sensor 6 by the heat recovery amount adjusting device 17, and the pressure is adjusted so that the pressure becomes the set pressure and the exhaust heat recovery amount increases when the pressure is high. When is low, the exhaust heat recovery amount is reduced. Therefore, of the heat recovered from the fuel cell main body 1, except the natural heat dissipation, the energy carried out by the steam used in the reformer 2 and the energy carried out by the blowdown water, the heat is recovered from the exhaust heat recovery heat exchanger 7 to the outside. To be done.

FIG. 5 shows the relationship between the amount of exhaust heat recovered in the exhaust heat recovery heat exchanger 7 and the amount of power generation to the outside of the fuel cell.
Is. The amount of exhaust heat recovered from the exhaust heat recovery heat exchanger 7 is determined from the heat balance in the battery cooling water system as described above.
When the fuel cell is generating power at the rated load, the steam supply to the reformer 2 with respect to the heat generation amount in the fuel cell main body 1,
Since the amount of heat released due to blowdown and natural heat dissipation is small,
The amount of exhaust heat recovered in the exhaust heat recovery heat exchanger 7 increases. On the other hand, when the fuel cell is generating power at about half of the rated load, the heat generation amount in the fuel cell body 1 is balanced with the steam supply to the reformer 2, blowdown water, and heat dissipation by natural heat dissipation. No heat is radiated from the heat recovery heat exchanger 7. Furthermore, when the power generation amount in the fuel cell is 0, the exhaust heat recovery amount increases again. The reason for this is that the fuel cell produces 0 electricity to the outside, but actually it produces electricity with a load of about half the rating in order to protect the cell, and the electricity generated is supplied to the electric heater in the cell cooling water system. It is because it is flowing. Therefore, heat can be recovered even when the amount of power generation to the outside of the fuel cell is 0, and the relationship shown in FIG. 5 is obtained. Therefore, when the fuel cell is operated near the rated power generation amount or near the power generation amount 0, the exhaust heat recovery heat exchanger 7 must recover the exhaust heat.

[0005]

By the way, in the exhaust heat recovery of the fuel cell according to the above conventional technique, the exhaust heat treatment including the exhaust heat recovery heat exchanger 7, the heat recovery amount control valve 8, the heat recovery amount adjusting device 17 and the like. If a part of the system fails and heat cannot be dissipated to the outside of the battery cooling water system, the pressure of the battery cooling water system rises, and steam is blown out from the safety valve 4 to dissipate heat, or the fuel cell is in an emergency. I have to stop.

However, the method of operating while ejecting water vapor of about 160 ° C. from the safety valve 4 is not a preferable method from the viewpoint of safety and maintenance. Further, the emergency stop of the fuel cell is not desirable because it makes it impossible to continue the power supply and leads to deterioration of the battery cell to shorten its life.

As described above, when the heat generated in the fuel cell body cannot be discharged to the outside of the cell cooling water system, there is a safety problem until now when the power generation is continued.
There is a problem in that if the power supply is stopped in an emergency, power cannot be supplied and the life of the battery cell is shortened.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fuel cell capable of continuously performing power generation operation safely even when exhaust heat treatment cannot be performed by an exhaust heat treatment apparatus of a fuel cell. It is in.

[0009]

In order to achieve the above object, in the fuel cell of the present invention, a fuel cell main body which inputs hydrogen and oxygen to generate power and generate heat, and the fuel cell main body are provided. Battery cooling water to be cooled, a water vapor separator for separating water vapor in the battery cooling water, a pressure sensor for measuring the pressure in the water vapor separator, and the above in order to keep the reaction temperature in the fuel cell main body constant. In a fuel cell provided with an exhaust heat treatment device for discharging heat generated during the power generation to the outside of the cell cooling water system so that the measured pressure becomes constant, in parallel with the control of the pressure in the steam separator by the exhaust heat treatment device. In addition, a control device for controlling the pressure in the water vapor separator to be constant by changing the power generation amount of the fuel cell is also provided.

[0010]

In the fuel cell of the present invention, even if the heat generated by the fuel cell is not exhausted to the outside of the cell cooling water system by the exhaust heat treatment device, the calorific value during power generation depends on the power generation of the fuel cell, and the cell is cooled by natural heat dissipation. Utilizing the fact that the reaction temperature of the fuel cell can be made constant by balancing only in the water system, the amount of power generation is changed to make the reaction temperature constant when the exhaust heat treatment device or the like is abnormal. Here, since the calorific value of the fuel cell and the pressure in the steam separator are correlated, by controlling the amount of power generation so that the pressure in the steam separator of the cell cooling water system becomes a set constant value, The amount of heat generated at that time is reduced to keep the reaction temperature constant, eliminating the need for exhaust heat to the outside of the cell cooling water system, and enabling safe power generation operation even when exhaust heat treatment cannot be performed by the exhaust heat treatment apparatus of the fuel cell.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the configuration of the first embodiment of the present invention. In this embodiment, a heat exchanger is used as an exhaust heat recovery device (exhaust heat treatment device).

In the figure, 1 is a fuel cell main body, 2 is a reformer, 3 is a steam separator, 4 is a safety valve, 5 is a controller, and 5 is a controller.
a is its signal line, 6 is a pressure sensor, 7 is an exhaust heat recovery heat exchanger, 8 is a heat recovery amount control valve, 11 is an inverter, 12 is a fuel cell electric output control device, 14 is a water treatment device, and 15 is an ejector. , 16 are battery cooling water circulation pumps.

The basic structure of this embodiment and the function of each part are as follows.
This is similar to the conventional example of FIG. That is, the fuel cell body 1
Then, the hydrogen in the reformed gas obtained by reforming the fuel in the reformer 2 and the oxygen in the air perform the opposite reaction of the electrolysis of water to generate electricity. In the phosphoric acid fuel cell, the power generation reaction at this time is carried out at a temperature of about 200 [° C.], and heat is generated. In order to keep the temperature of the fuel cell body 1 constant at about 200 [° C.] and to dissipate the generated heat to the outside of the fuel cell body 1, the cell cooling water is circulated into the fuel cell body 1 by the cell cooling water circulation pump 16. ing. The heat generated by the fuel cell body 1 is recovered by converting high-temperature water in the cell cooling water system into steam. A part of the recovered heat is mixed with fuel from the steam separator 3 through the ejector 15 and sent to the reformer 2 in order to carry out the reforming reaction as steam. In addition, the reformer 2
A part of the battery cooling water is blown down to the water treatment device 14 in order to prevent the concentration of impurities in the battery cooling water due to the discharge of water vapor. A part of the recovered heat is discharged together with the blowdown water. The remaining heat is the waste heat recovery heat exchanger 7
It is condensed and is radiated to the outside by the secondary cooling water. The amount of heat recovered by the exhaust heat recovery heat exchanger 7 is controlled by operating the exhaust heat recovery control valve 8 of the secondary cooling water. That is, the exhaust heat recovery control valve 8 detects the pressure of the water vapor separator 3 with the pressure sensor 6 by the control device 5, and when the pressure is high so that the pressure becomes the set pressure, the exhaust heat recovery amount. So that the exhaust heat recovery amount decreases when the pressure is low. Therefore, of the heat recovered from the fuel cell main body 1, except for natural heat dissipation and the energy carried out by the steam used in the reformer 2 and the energy carried out by the blowdown water, the exhaust heat recovery heat exchanger uses the secondary cooling water. Heat is radiated from 7 to the outside.

Here, when the exhaust heat recovery heat exchanger 7 cannot perform the exhaust heat treatment, unless the control device 5 performs the control other than the above, the steam pressure in the steam separator 3 as described in the conventional example. Rises, and if power generation is continued as it is, steam must blow off from the safety valve 4 attached to the steam separator 3, and the power generation operation must be stopped urgently. Therefore, in the present embodiment, as a point different from the conventional example of FIG. 6, the electric output of the fuel cell converted into the AC output through the inverter 11 is connected so as to be output via the fuel cell electric output control device 12. The fuel cell electric output control device 12 is controlled by the control device 5 to control the power generation amount of the fuel cell so that the pressure in the steam separator 3 becomes constant before the safety valve 4 operates, as described below.

As described above, FIG. 5 is a diagram showing the relationship between the amount of power generated outside the fuel cell and the amount of exhaust heat recovered by the exhaust heat recovery heat exchanger 7. As shown in this figure, when the power generation amount is about 50% of the rated value, the exhaust heat recovery amount in the exhaust heat recovery heat exchanger becomes 0 (point A). Further, when the amount of power generation is further reduced, the amount of heat recovery increases from a certain amount of power generation (point B is the point at which the amount of heat begins to increase). Therefore, when the exhaust heat recovery heat exchanger 7 cannot dissipate the exhaust heat to the outside of the battery cooling water system, if the operation is performed at the power generation amount between the points A and B, the safety valve 4 is not operated and the power generation is performed. The operation can be continued.

Therefore, when the pressure in the water vapor separator 3 measured by the pressure sensor 6 has reached a pressure slightly lower than the pressure at which the safety valve 4 operates, and the exhaust heat recovery heat exchanger 7 cannot perform the exhaust heat treatment, The fuel cell load is calculated in the control device 5 from the measured value of the pressure sensor 6 and the set pressure value in the water vapor separator 3, and the fuel cell electric output control device is operated by the signal generated from the control device 5 based on the calculation result. 12, the load of the fuel cell is reduced, the amount of power generation in the fuel cell main body 1 is reduced, and the amount of heat generated in the cell main body 1 and the amount of heat generated by the steam used in the reformer 2 and the blowdown water are also generated. The exhaust heat recovery heat exchanger 7 is operated at a power generation amount that does not require exhaust heat recovery so that the sum of heat amount and natural heat dissipation amount is balanced. At this time, if the amount of power generation is made too low, point B in FIG. 5 will be exceeded and heat recovery by the exhaust heat recovery heat exchanger 7 will be required again, and the pressure in the steam separator 3 will rise.
A lower limit value is set for the fuel cell load calculated by the control device 5. By this method, the power generation operation can be continued even when the exhaust heat recovery heat exchanger 7 cannot perform the exhaust heat treatment.

FIG. 2 shows the configuration of the second embodiment of the present invention. In this embodiment, a steam cooked absorption refrigerator is used as an exhaust heat recovery device.

In the figure, 1 is a fuel cell main body, 2 is a reformer, 3 is a steam separator, 4 is a safety valve, 5 is a controller, and 5 is a controller.
a is its signal line, 6 is a pressure sensor, 9 is a steam discharge control valve, 10 is an absorption refrigerator, 11 is an inverter, 12 is a fuel cell electric output control device, 14 is a water treatment device, 15 is an ejector, 16 Indicates a battery cooling water circulation pump.

In this embodiment, an absorption refrigerating machine 10 is used in place of the exhaust heat recovery heat exchanger 7 of the first embodiment, and the absorption refrigerating machine 10 is supplied with a fuel via a steam discharge control valve 9. Water vapor of the battery cooling water system generated by heat recovery in the battery body 1 is supplied. In the present embodiment, as in the first embodiment, the exhaust heat treatment cannot be performed due to a failure of the absorption refrigerator 10, and the pressure in the steam separator 3 rises, and the preset pressure value (safety valve 4 (A little lower than the pressure at which the fuel cell operates), the load of the fuel cell is reduced by the fuel cell electric output control device 12 by the signal from the control device 5, and the amount of power generation in the fuel cell main body 1 is reduced. The heat generation of the fuel cell. As a result, the power generation operation can be maintained without radiating heat to the outside of the battery cooling water system (while keeping the steam discharge amount control valve 9 closed).

FIG. 3 shows the configuration of the third embodiment of the present invention.

In the figure, 1 is a fuel cell main body, 2 is a reformer, 3 is a steam separator, 4 is a safety valve, 5 is a controller, and 5 is a controller.
a is its signal line, 6 is a pressure sensor, 7 is an exhaust heat recovery heat exchanger, 8 is a heat recovery amount control valve, 11 is an inverter, 12 is a fuel cell electric output control device, 13 is a commercial power supply control device, 1
Reference numeral 4 is a water treatment device, 15 is an ejector, 16 is a battery cooling water circulation pump, and 18 is a commercial power source.

This embodiment is similar to the first embodiment in that a heat exchanger is used as an exhaust heat recovery device. The difference is that the commercial power source 18 outputs the fuel cell electrical output via the commercial power source controller 13. Connect to the fuel cell output from the controller 12,
The point is that the fuel cell output and the commercial power supply 18 are operating in coordination.

Here, when the exhaust heat recovery heat exchanger 7 cannot recover the exhaust heat and the temperature inside the steam separator 3 rises, the detected value of the pressure sensor 6 and the pressure setting of the steam separator 3 are set. Based on the value, the control device 5 calculates the load sharing amount on the fuel cell side and the commercial power supply 18 side, and the signal from the control device 5 causes the fuel cell output control device 12 to reduce the load amount on the fuel cell side. By increasing the load on the commercial power supply 18 side in the commercial power supply control device 13,
The amount of heat generated in the fuel cell main body 1,
Power generation that does not need to recover exhaust heat in the exhaust heat recovery heat exchanger 7 by balancing the amounts of heat generated by the steam used in the reformer 2, the heat generated by blowdown water, and the natural heat dissipation. Drive in quantity. At this time, the lower limit value is set for the fuel cell load sharing amount calculated by the control device 5 as in the first embodiment. In the method of this embodiment, since the interconnection operation with the commercial power source 18 is performed, when the exhaust heat cannot be released from the exhaust heat recovery heat exchanger 7 and the power generation amount in the fuel cell is reduced, Commercial power source 1
It is possible to increase the load sharing amount of No. 8 and control so as to keep the amount of electricity used outside constant.

FIG. 4 shows the configuration of the fourth embodiment of the present invention.

In the figure, 1 is a fuel cell main body, 2 is a reformer, 3 is a water vapor separator, 4 is a safety valve, 5 is a controller, and 5 is a controller.
a is a signal line, 6 is a pressure sensor, 9 is a steam discharge control valve, 10 is an absorption refrigerator, 11 is an inverter, 12 is a fuel cell electric output control device, 13 is a commercial power supply control device, 1
Reference numeral 4 is a water treatment device, 15 is an ejector, 16 is a battery cooling water circulation pump, and 18 is a commercial power source.

In the present embodiment, as in the second embodiment, when the absorption refrigerator 10 is used as the exhaust heat recovery device, the fuel cell output of the third embodiment and the commercial power supply 18 are interconnected. It is an example of performing. In the present embodiment, since the interconnection operation with the commercial power source 18 is performed as in the third embodiment, when the heat dissipation to the absorption refrigerator 10 cannot be performed and the power generation amount in the fuel cell is reduced. In addition, the load sharing amount of the commercial power source 18 can be increased by the decrease amount, and control can be performed so as to keep the amount of electricity used outside constant.

In the above embodiment, the exhaust heat recovery apparatus has been described on the assumption that exhaust heat recovery is completely stopped. However, the exhaust heat recovery apparatus is in an operating state although the exhaust heat recovery capability is considerably lowered. Even if the exhaust heat treatment capacity is lowered due to some reason, it is obvious that the power generation amount can be changed according to the characteristic diagram of FIG. 5, and the power generation operation can be safely continued so that the safety valve does not operate. be able to.
As described above, the present invention can be applied in various ways in accordance with the gist thereof and can take various embodiments.

[0029]

As is apparent from the above description, according to the fuel cell of the present invention, even if the heat dissipating apparatus cannot dissipate heat to the outside, the power supply can be continued without stopping the fuel cell in an emergency. Therefore, it is possible to prevent the deterioration of the fuel cell unit and obtain the effect of extending the life, and
The effect of improving the reliability of the entire power supply system can also be obtained.

[Brief description of drawings]

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

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

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a power generation amount and an exhaust heat recovery amount in a fuel cell.

FIG. 6 is a configuration diagram of a conventional fuel cell.

[Explanation of symbols]

 1 ... Fuel cell main body 2 ... Reformer 3 ... Steam separator 4 ... Safety valve 5 ... Control device 6 ... Pressure sensor 7 ... Exhaust fuel recovery heat exchanger 8 ... Heat recovery amount control valve 9 ... Steam exhaust amount control valve 10 ... Absorption refrigerator 11 ... Inverter 12 ... Fuel cell electric output control device 13 ... Commercial power supply control device 14 ... Water treatment device 18 ... Commercial power supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Adachi 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Toyoichi Tamura 1-5-20 Kaigan, Minato-ku, Tokyo No. Tokyo Gas Co., Ltd. (72) Inventor Kunihiro Nishizaki 1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd.

Claims (3)

[Claims] 1. A fuel cell main body that inputs hydrogen and oxygen to generate electricity and generate heat, a cell cooling water that cools the fuel cell main body, and a water vapor separator that separates water vapor in the cell cooling water. A pressure sensor for measuring the pressure in the water vapor separator, and a heat generated during the power generation so that the measured pressure becomes constant in order to keep the reaction temperature in the fuel cell main body constant outside the cell cooling water system. In the fuel cell having an exhaust heat treatment device for discharging the steam, the steam separation is performed by changing the power generation amount of the fuel cell in parallel with or switching the control of the pressure in the steam separator by the exhaust heat treatment device. A fuel cell comprising a control device for controlling the pressure inside the container to a constant value. 2. A fuel cell main body that inputs hydrogen and oxygen to generate power and generate heat, a cell cooling water that cools the fuel cell main body, and a water vapor separator that separates water vapor in the cell cooling water. A pressure sensor for measuring the pressure in the water vapor separator, and a heat generated during the power generation so that the measured pressure becomes constant in order to keep the reaction temperature in the fuel cell main body constant outside the cell cooling water system. In the fuel cell provided with the exhaust heat treatment apparatus for discharging to the fuel cell, the fuel cell is detected when the pressure sensor detects that the steam separator pressure has risen because the exhaust heat treatment apparatus does not or cannot perform the exhaust heat treatment. A control device for reducing the amount of heat generated from the fuel cell main body to reduce the amount of power generation of the water vapor separator to a predetermined value and returning the steam separator pressure to a set value. Fuel cell and said Rukoto. 3. A fuel cell main body that inputs hydrogen and oxygen to generate power and generate heat, a cell cooling water that cools the fuel cell main body, and a water vapor separator that separates water vapor in the cell cooling water. A pressure sensor for measuring the pressure in the water vapor separator, and a heat generated during the power generation so that the measured pressure becomes constant in order to keep the reaction temperature in the fuel cell main body constant outside the cell cooling water system. In a fuel cell equipped with an exhaust heat treatment device that discharges into the fuel cell, the pressure sensor indicates that the steam separator pressure has risen because the exhaust heat treatment device does not or cannot perform the exhaust heat treatment during the interconnection operation with the commercial power source. When detected by
By reducing the load sharing amount of the fuel cell and increasing the load sharing amount of the commercial power source, the power generation amount from the fuel cell body is reduced to a predetermined value and the heat generation amount from the fuel cell body is reduced. A fuel cell comprising a controller for controlling the pressure of the water vapor separator to return to a set value.