JPH10223245A - Fuel cell electricity-generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell type electricity-generating apparatus in which neither water-hammer phenomenon nor sludge deposition occur, steam pressure control can stably be carried out, and a heat output-controllable heat output system is installed. SOLUTION: This electricity-generating apparatus comprises fuel cells 1, each of which is a layered body of a unit cell and a cooling plate 3 having a cooling pipe 4, a circulation pump 11 to circulate cell cooling water 5 at a prescribed temperature in the cooling pipe, a steam separator 12, a cooling water circulating system 10 comprising a heat exchanger 21 for heat output which works also as a heat exchanger for cooling, and a heat output system 20 for heating the secondary cooling water 15 of the system 10 to hot water at non-boiling temperature and carry out heat output. The apparatus further comprises a heat output controlling means 30 for controlling the water flowing rate of the cell cooling water to the heat exchanger for heat output, corresponding to the alteration of the saturated steam pressure and the controlling means 30 comprises a pressure-adjusting part 22 to detect the alteration of the saturated steam pressure in the steam separator 12 and generates a control signal 22S and a three-way control valve 31, which receives the control signal to control the water flowing rate of the cell cooling water to the heat exchanger for heat output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-cooled fuel cell power generation apparatus for performing the output of generated power and the heat output for utilizing waste heat in parallel, and more particularly, to utilizing heat output using battery cooling water as a heat source. The present invention relates to a fuel cell power generator that supplies hot water at an unboiled temperature to equipment.

[0002]

2. Description of the Related Art FIG. 2 is a system diagram showing a main part of a conventional fuel cell power generator provided with a heat output device. A phosphoric acid type fuel cell 1 has a fuel electrode and air with a matrix holding phosphoric acid interposed therebetween. It is composed of a stack of unit cells provided with electrodes, and the fuel gas generated by the fuel reformer 2 is supplied to the fuel electrodes.
By supplying air to the air electrode, power generation is performed based on an electrochemical reaction. In addition, the electrochemical reaction of the fuel cell 1 is an exothermic reaction as a whole, and cooling of the fuel cell is necessary to maintain the temperature of the fuel cell 1 at an operating temperature of, for example, about 190 ° C. and perform efficient power generation operation. Will be needed.
Therefore, a cooling plate 3 including a cooling pipe 4 using pure water as a cell cooling water 5 is laminated on the fuel cell 1.
At a predetermined temperature lower than the operating temperature, for example, 160 to 170 °.
A cooling water circulation system 10 including a cooling water circulation pump 11, a steam separator 12, and a cooling heat exchanger 13 is connected to the cooling pipe 4 to circulate the battery cooling water 5 of about C.

[0003] On the other hand, in order to reform the raw fuel into a hydrogen-rich fuel gas, fuel reforming is performed by adding a reforming steam to methane gas or the like as the raw fuel to promote the reaction between water and methane with a catalyst. A reformer 2 is used, and a part of the saturated steam separated by the steam separator 12 is used for the reforming steam. Therefore, it is necessary to supply pure water to the cooling water circulation system 10 in accordance with the amount of saturated steam used for reforming the fuel. This water is ion-exchanged water from which impurities in tap water are removed by a water treatment system (not shown). Further, water (power generation water) contained in the air off-gas discharged from the air electrode of the fuel cell 1 and recovered water obtained by condensing water (combustion water) in the combustion exhaust gas of the burner of the fuel reformer 2 are used. It has less impurities than tap water and can reduce the load on the ion-exchange type water treatment equipment installed in a water treatment system (not shown). There is also known a fuel cell power generation system that recovers moisture.

When the heat generated by the power generation of the fuel cell 1 is to be recovered and output as a heat source of a heat utilization facility such as an air conditioning facility or a hot water supply facility, a cooling heat exchanger 13 provided in a cooling water circulation system 10 is provided. Is used as a heat output heat exchanger, the configuration of the heat output system 20 can be greatly simplified. Therefore, in the conventional fuel cell power generator, the heat output system 20 is used as the heat output heat exchanger 21 as shown in FIG.
Heat exchange is performed by using the battery cooling water 5 flowing into the first cooling medium 5 as a heating medium, and the secondary cooling water 15 supplied from the secondary cooling water line 26 as a medium to be heated. Is supplied through a hot water line 27 to, for example, a heat utilization facility.

[0005] In the above-described heat output system 20, in order to control the heat exchange amount of the heat output heat exchanger 21, the temperature of the battery cooling water 15 in the steam separator 12 is determined by controlling the operating temperature of the fuel cell 1. Temperature suitable for holding (for example, 160 to 170
° C) and control to keep the temperature of the hot water 25 at a non-boiling temperature (for example, around 95 ° C in the case of normal pressure) determined according to the water pressure on the heat utilization facility side are required. . Thus, the conventional heat output system 20 is used as a heat output control means as a saturated steam pressure detecting unit 22 in the steam separator 12.
A, and a pressure controller 22 comprising a controller 22B for outputting a signal for correcting a difference between the detected value and the reference value, and a heat output heat exchanger receiving the output control signal 22S of the pressure controller 22. And a control valve 23 for controlling the flow rate of the battery cooling water 5 to the battery 12. The control valve 23 controls the ratio between the amount of secondary cooling water supplied to the heat output heat exchanger 21 and the amount of water bypassed to the bypass line 28. By controlling the saturated steam pressure in the steam separator 12, the steam pressure is adjusted to a steam pressure corresponding to a battery cooling water temperature of 160 to 170 ° C., for example.
The pressure is maintained at about 6 to 0.8 MPa.

[0006]

During operation of the conventional fuel cell power generator having the heat output system 20 constructed as described above, for example, when a sudden increase in the electric output is commanded, the fuel from the steam separator 12 is output. Since the amount of the reforming steam supplied to the reforming device 2 increases rapidly, and the saturated steam pressure in the steam separator 12 decreases sharply with this, the pressure control unit 22 that senses this detects the flow ratio of the control valve 23. The bypass line 2
Control is performed so as to increase to the 8 side. Therefore, the amount of the secondary cooling water 15 flowing into the heat output heat exchanger 21 is rapidly reduced or stopped. On the other hand, since the flow rate of the battery cooling water 5 flowing into the heat output heat exchanger 12 does not decrease, the secondary cooling water staying in the heat output heat exchanger is overheated to a bumping state. Noise is generated based on the phenomenon. For this reason, the low noise performance of the fuel cell power generation device, which is characterized by no pollution, is hindered, and there is a problem that the image of the fuel cell power generation device that is environmentally friendly is reduced.

In addition, mechanical vibrations are generated in the heat output heat exchanger due to the water hammer phenomenon, so that the heat output heat exchanger is likely to be mechanically damaged and sludge is generated due to boiling of the secondary cooling water. There is also a problem that the sediment easily accumulates and the traces of chlorine contained in the sludge promote the corrosion of heat exchange tubes, etc., which leads to a reduction in the service life of the heat exchanger for heat output and an increase in maintenance costs. I do.

An object of the present invention is to provide a fuel cell power generator having a heat output system capable of performing stable steam pressure control and heat output control without water hammer phenomenon and sludge accumulation.

[0009]

In order to solve the above-mentioned problems, this fuel cell power generator comprises a fuel cell comprising a laminate of a unit cell and a cooling plate having a cooling pipe; A cooling water circulating system including a circulation pump for circulating the battery cooling water, a steam separator, and a cooling heat exchanger disposed upstream thereof, and using the cooling heat exchanger as a heat output heat exchanger. A heat output system for heating the secondary cooling water to hot water at an unboiled temperature and outputting heat therefrom, wherein the flow rate of the battery cooling water to the heat output heat exchanger is A heat output control means is provided for controlling in response to a change in the saturated steam pressure in the steam separator.

Here, the heat output control means detects a saturated steam pressure in the steam separator, and outputs a signal for correcting a difference between the detected value and a reference value, and a pressure adjusting section for the pressure adjusting section. A control valve that receives the output control signal and controls the flow rate of the battery cooling water to the heat output heat exchanger. The control valve has one discharge port connected to the battery cooling water inlet side of the heat output heat exchanger and the other discharge port connected to the bypass flow path side of the heat output heat exchanger to control the flow division ratio. A three-way control valve.

Further, the heat output system may be configured to include a control valve and a temperature control unit for controlling the amount of the secondary cooling water to maintain the hot water temperature at the non-boiling temperature. In the fuel cell power generator according to the present invention, the flow rate of the battery cooling water of the heat output heat exchanger also serving as the heat exchanger for cooling the battery cooling water is controlled by the heat output control means to determine the saturated steam pressure in the steam separator. Since the control is performed in response to the change, for example, when the amount of the reforming steam rapidly increases and the saturated steam pressure in the steam separator 12 suddenly decreases, the supply amount of the battery cooling water to the heat output heat exchanger immediately decreases, Since the heat output of the heat output heat exchanger decreases with this, a constant amount of secondary cooling water is always supplied to the heat output heat exchanger. To avoid the occurrence of noise by avoiding bumping of the secondary cooling water and the water hammer phenomenon, and to avoid the vibration of the heat output heat exchanger and the increase in sludge accumulation due to the bumping of the secondary cooling water. Can be.

Here, if the heat output control means is constituted by a pressure adjusting section and a control valve for controlling the flow rate of the battery cooling water to the heat output heat exchanger, the saturated steam pressure generated by the pressure adjusting section can be reduced. The control valve operates according to the signal that corrects the difference between the detected value and the reference value, and controls the flow rate of the battery cooling water to the heat output heat exchanger. It can be carried out.

If the control valve is used as a three-way control valve to control the split ratio between the heat output heat exchanger and the amount of battery cooling water flowing to the bypass passage, for example, when the amount of reforming steam increases sharply, water vapor is separated from the fuel cell. Operation to prevent a drop in saturated water vapor pressure by rapidly increasing the supply of high-temperature battery cooling water to the heat exchanger, and to prevent bumping of secondary cooling water by reducing the supply of battery cooling water to the heat output heat exchanger. In parallel and smoothly.

Further, the heat output system includes a control valve and a temperature control section for maintaining the hot water temperature at a non-boiling temperature by controlling the amount of the secondary cooling water, so that the secondary cooling water can flow in a flow rate range where the secondary cooling water does not bump. By controlling the amount of the secondary cooling water, the hot water temperature can be maintained near the upper limit of the unboiled temperature and supplied to the heat utilization facility.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a system diagram showing a main part of a fuel cell power generator according to an embodiment of the present invention. Members denoted by the same reference numerals as those of the conventional example have the same functions as those of the conventional example, and therefore description thereof will be omitted. . In the figure, a fuel cell power generation device has a heat output system 20 and a circulation pump 11 of a cooling water circulation system 10.
And a heat output heat exchanger 21 also serving as a heat exchanger for cooling the battery cooling water 5 upstream of the steam separator 12.
The battery cooling water temperature in the steam separator 12 is set to 160 to 170
° C and circulates through the cooling pipe 4 of the fuel cell 1 to perform a cooling action to maintain the fuel cell 1 at the operating temperature (190 ° C) and absorb heat generated by the power generation of the fuel cell 1 to maintain the operating temperature. The secondary cooling water 15 supplied through the secondary cooling water line 26 in the heat output heat exchanger 21 is heated to the unboiled hot water 25 by using the battery cooling water 5 whose temperature has been raised nearby as a superheating medium. It is configured to perform a heat output function of supplying heat to a heat utilization facility (not shown) via the hot water line 27. Also,
The heat output control means 30 of the heat output system 20 includes the steam separator 1
A pressure regulator 22 for detecting a saturated water vapor pressure within 2 and outputting a signal 22S for correcting a difference between the detected value and a reference value;
A three-way control valve 31 is provided which receives the output control signal 22S of the pressure adjusting unit 22 and controls the flow rate of the battery cooling water to the heat output heat exchanger 21.

The three-way control valve 31 is provided on the upstream side of the steam separator 12 and absorbs the heat generated by the power generation of the fuel cell 1 to heat the cell cooling water 5 whose temperature has risen to near the operating temperature of the fuel cell. It is configured to diverge to the output heat exchanger 21 side and the bypass flow path 32 side. The split ratio is controlled by the output control signal 22S of the pressure control unit 22. For example, when the saturated steam pressure in the steam separator 12 exceeds a reference value (a constant value in the range of 0.6 to 0.8 MPa). The flow rate on the heat output heat exchanger 21 side is increased to increase the heat output of the heat output heat exchanger, and when the saturated steam pressure falls below the reference value, the flow rate to the bypass flow path side is increased. To increase the steam pressure in the steam separator 12 and to reduce the heat output of the heat output heat exchanger. Therefore,
The temperature of the battery cooling water 5 in the steam separator 12 is stably maintained at 160 to 170 ° C. which is balanced with the reference value of the saturated steam pressure, and the fuel cell 1 is stabilized by the battery cooling water 5 at the optimum operating temperature. The power generation operation is performed while holding.

On the other hand, the heat output heat exchanger 21 outputs a surplus amount of heat excluding the amount of heat consumed for maintaining the temperature of the battery cooling water in the steam separator using the hot water 25 as a medium to be heated, and outputs, for example, a fuel. When a sudden increase in the electrical output of the battery power generation device is instructed and the amount of reforming steam rapidly increases, and the saturated steam pressure in the steam separator 12 sharply decreases, the supply of the battery cooling water 5 to the heat output heat exchanger 21 is immediately performed. Since the heat output of the heat output heat exchanger decreases as the amount decreases, the heat output is temporarily reduced by constantly flowing the secondary cooling water 15 through the heat output heat exchanger. Although the temperature of the hot water 25 is reduced to a low level, the occurrence of noise can be prevented by avoiding the bumping of the secondary cooling water 15 and the water hammer phenomenon, and the heat for heat output caused by the bumping of the secondary cooling water. Exchanger vibration and sludge accumulation The advantage of avoiding an increase in the amount is obtained.

The pressure control section 22 of the heat output control means 30 may be replaced with a pressure control section for maintaining the battery cooling water temperature in the steam separator 12 at its reference temperature of 160 to 170 ° C. Since the saturated steam pressure and the battery cooling water temperature are in an equilibrium state in the separator 12, the same operation and effect as in the above-described embodiment can be obtained. Further, if the heat output system is provided with a control valve and a temperature control unit for maintaining the temperature of the hot water 25 at the non-boiling temperature by controlling the flow rate of the secondary cooling water 15 on the secondary cooling water line 26 side, By controlling the amount of secondary cooling water in a flow rate range in which the secondary cooling water does not boil, the hot water temperature can be maintained near the upper limit of the unboiled temperature and supplied to the heat utilization equipment. In the case where a heat storage tank or the like using the hot water 25 as a heat source is provided, there is an advantage that the temperature of the hot water can be maintained at a substantially constant temperature and heat can be easily used. In addition, you may comprise so that a control valve and a temperature control part may be provided in the heat utilization equipment side.

[0019]

As described above, the fuel cell power generator according to the present invention controls the flow rate of the battery cooling water to the heat output heat exchanger also serving as the battery cooling water cooling heat exchanger by controlling the heat output control means. Thus, the control is performed in accordance with the change in the saturated steam pressure. As a result, when the saturated steam pressure in the steam separator decreases, the supply amount of battery cooling water to the heat output heat exchanger immediately decreases, and the heat output of the heat output heat exchanger decreases. By flowing the amount of secondary cooling water to the heat output heat exchanger, it is possible to prevent the secondary cooling water bumping and water hammer phenomena, which were problems in the prior art, to prevent the generation of noise, and Since the vibration of the heat output heat exchanger and the increase of sludge accumulation due to bumping of the cooling water can be avoided, low noise, long service life, easy maintenance, and stable steam pressure control and stable heat output control are achieved. It is possible to provide a fuel cell power generation device provided with a heat output system that can be used.

Here, if the heat output control means is configured to control the split ratio of a control valve, for example, a three-way control valve, by a signal generated by the pressure control section, the saturated steam pressure in the steam separator is set to its reference value. The operation of holding and stabilizing the cooling performance of the fuel cell and the operation of restricting the supply of battery cooling water to the heat output heat exchanger to control the heat output and prevent bumping of the secondary cooling water are performed in parallel. It is possible to provide a fuel cell power generation device having a function of performing the operation smoothly.

[Brief description of the drawings]

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

FIG. 2 is a system diagram showing a main part of a conventional fuel cell power generator equipped with a heat output device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel reformer 3 Cooling plate 4 Cooling pipe 5 Battery cooling water 10 Cooling water circulation system 11 Circulation pump 12 Steam separator 13 Cooling heat exchanger (also used as heat output heat exchanger) 15 Secondary cooling water 20 Heat output system 21 Heat exchanger for heat output (also used as heat exchanger for cooling) 22 Pressure regulator 22A Detector 22B Regulator 22S Control signal 23 Three-way control valve 25 Hot water 26 Secondary cooling water line 27 Hot water line 30 Heat output Control means 31 Three-way control valve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiya Omura 3-3-3305-522, Shiomidai, Isogo-ku, Yokohama-shi, Kanagawa (72) Inventor Nobuhiro Iwasa 910-55, Katsuragi-cho, Kishiwada-shi, Osaka (72) Inventor Takuo Hagino 1-33 Maeda-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture

Claims (4)

[Claims] 1. A fuel cell comprising a laminate of a unit cell and a cooling plate having a cooling pipe, a circulation pump for circulating battery cooling water at a predetermined temperature through the cooling pipe, a steam separator, and an upstream side thereof. A cooling water circulating system including a cooling heat exchanger and the cooling heat exchanger also serving as a heat output heat exchanger, and the secondary cooling water is heated to a non-boiling temperature to output heat. A heat output control means for controlling a flow rate of battery cooling water to the heat output heat exchanger in accordance with a change in saturated steam pressure in the steam separator. A fuel cell power generator comprising: 2. A heat output control means for detecting a saturated steam pressure in a steam separator and outputting a signal for correcting a difference between the detected value and a reference value, and an output of the pressure adjuster. 2. The fuel cell power generator according to claim 1, further comprising a control valve that receives a control signal and controls a flow rate of battery cooling water to the heat output heat exchanger. 3. The control valve has one discharge port connected to the battery cooling water inlet side of the heat output heat exchanger, and the other discharge port connected to the bypass flow path side of the heat output heat exchanger, thereby controlling the flow division ratio. 3. The fuel cell power generator according to claim 2, which is a three-way control valve for controlling. 4. The fuel cell power generation system according to claim 1, wherein the heat output system includes a control valve and a temperature control section for maintaining the hot water temperature at a non-boiling temperature by controlling the amount of secondary cooling water. apparatus.