JP2008152999A - Fuel cell power generation system and program thereof - Google Patents

Abstract

To provide a fuel cell power generation system capable of stably cooling a fuel cell (2) using low-temperature water in a lower part of a hot water tank (10) when water breakage occurs during power generation.
SOLUTION: A fuel cell 2 that generates electric power and heat using fuel gas and an oxidant gas, a heat exchanging means 8 for exchanging exhaust heat generated by power generation of the fuel cell with hot water, and hot water of the heat exchanging means. A hot water tank 10 for storing hot water, a hot water circulation path 11 that is a path for circulating hot water in the hot water tank, and a hot water circulation pump 9 that circulates hot water in the hot water circulation path, and a heat exchange means and hot water storage From a fuel cell cooling means 16 comprising a tank, a hot water circulation path and a hot water circulation pump, a water break detection means 17 for detecting a water break in the water supply to the hot water tank, and a control device for sequentially controlling the fuel cell, the cooling means, etc. In the fuel cell power generation system, the control device stops the power generation and operates the cooling means to the maximum when the water stoppage is detected by the water stoppage detection means during power generation.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell power generation system that generates electric power and heat and a program thereof.

A fuel cell generates electricity by reacting a fuel gas such as hydrogen and an oxidant gas such as oxygen, while generating heat simultaneously with the electric power. A fuel cell power generation system is known that supplies the generated power and heat to an external load composed of a power load such as a home appliance or a heat load such as shower hot water. At this time, the heat generated from the fuel cell power generation system is stored as hot water in a hot water tank (see, for example, Patent Document 1).
JP 2004-53120 A

  However, in the conventional configuration, the hot water tank has a structure in which high temperature water is stacked on the top and low temperature water is stacked on the bottom, and the low temperature water at the bottom of the hot water tank used for cooling the fuel cell is constantly supplied from outside tap water. Since it is assumed that it can be supplied from (city water), if water shut-off treatment is taken due to drought, etc., power generation operation will continue without detecting water shut-off and even low temperature water at the bottom of the hot water tank Even if power generation is stopped after heating, the fuel cell cannot be cooled and left in a high temperature state, and as a result, the chemical reaction inside the fuel cell is greatly accelerated compared to that of the standard, However, there is a problem that oxidation of the fuel cell internal catalyst by the oxidant gas is rapidly promoted to cause remarkable deterioration.

  The present invention solves the conventional problem, and in a fuel cell power generation system including a stratified hot water tank that collects heat generated in a fuel cell and stores the heat in a hot water storage tank, An object of the present invention is to provide a fuel cell power generation system capable of stably cooling a fuel cell using low temperature water in the lower part of the tank.

  In order to solve the conventional problems, the fuel cell power generation system according to the present invention comprises a cooling means comprising a heat exchange means, a hot water tank, a hot water circulation path, and a hot water circulation pump when water breakage is detected during power generation. It is designed to work as much as possible.

  Thereby, in the fuel cell power generation system provided with a stratified hot water storage tank that collects heat generated in the fuel cell and stores the heat in the hot water storage tank, in the event of a water outage during power generation, in parallel with stopping the power generation operation, Rapid operation of the fuel cell by the heat exchange means until the cooling means is operated to the maximum, specifically, the hot water circulation pump is operated at its maximum capacity and the low temperature water is heated up using the low temperature water at the bottom of the hot water tank. It is possible to cool, and as a result, it is possible to suppress the oxidation of the catalyst by the oxidant gas accumulated inside the fuel cell, so that the deterioration of the fuel cell can be suppressed.

  According to the fuel cell power generation system of the present invention, in a fuel cell power generation system including a stratified hot water tank that collects heat generated in the fuel cell and stores the heat in the hot water storage tank, when water breakage occurs during power generation, power generation operation is performed. In parallel with the stoppage, the cooling means is operated to the maximum, specifically, the hot water circulation pump is operated at the maximum capacity and the low temperature water is heated using the low temperature water at the bottom of the hot water tank until it disappears. The fuel cell can be rapidly cooled by the heat exchanging means, and as a result, the oxidation of the catalyst by the oxidant gas accumulated inside the fuel cell can be suppressed, so that deterioration of the fuel cell can be suppressed.

  According to a first aspect of the present invention, there is provided a fuel cell that generates electric power and heat using a fuel gas and an oxidant gas, a heat exchanging unit that exchanges exhaust heat accompanying the power generation of the fuel cell with hot water, A hot water storage tank for storing hot water, a hot water circulation path for circulating hot water in the hot water tank between heat exchange means, a hot water circulation pump for circulating hot water in the hot water circulation path, the heat exchange means and the hot water storage tank, A fuel cell cooling means having a hot water circulation path and a hot water circulation pump; a water failure detection means for detecting a water break in the water supply to the hot water tank; and a control device for controlling at least the fuel cell and the cooling means. The control device generates a fuel cell power generation system by stopping power generation and operating the cooling means to the maximum when water breakage is detected by the water breakage detection means during power generation. In a fuel cell power generation system equipped with a stratified hot water storage tank that collects the stored heat and stores it in the hot water storage tank, when the water outage occurs during power generation, the cooling means is operated to the maximum in parallel with stopping the power generation operation. Specifically, the hot water circulating pump is operated at its maximum capacity, and the low temperature water is heated using the low temperature water at the bottom of the hot water tank until the low temperature water is heated and disappears. Since the oxidation of the catalyst by the oxidant gas accumulated inside can be suppressed, the deterioration of the fuel cell can be suppressed.

  In particular, the second aspect of the invention is a fuel cell power generation system according to the first aspect of the invention, further comprising a residual heat amount detection means for detecting the amount of hot water in the hot water tank, and the control device has a predetermined amount of residual heat detected by the residual heat amount detection means. The power generation operation is continued until the value reaches the value, and the cooling means is not operated, so that it is possible to continue the power generation as long as the minimum cooling water used for cooling during the stop process is secured. Even if a short-time water outage occurs in the installation environment of the fuel cell power generation system, the power generation is not stopped sensitively.

  The third aspect of the invention is particularly provided with display means for displaying the state of the fuel cell power generation system in the fuel cell power generation system of the first aspect of the invention, and when the control means detects water breakage by the water breakage detection means, the display means By displaying the fact that a water break has occurred, it is possible to let the user know why the fuel cell power generation system has stopped, and although it is rare, external tap water piping (city water is supplied) If the incoming water pipe) is damaged, you will be able to quickly notice any changes.

  The fourth aspect of the invention is a fuel cell power generation system according to any one of the first to third aspects of the invention, particularly comprising a stirring means for stirring the hot water in the hot water tank, and the control means detects water breakage by the water breakage detection means. In this case, by controlling the temperature in the hot water storage tank with the stirring means, the hot water storage tank 10 is forced to mix the hot water in the hot water tank and the cold water in the hot water tank 10 so that the hot water storage tank 10 can be used in a disaster. It is possible to avoid a dangerous state such as the hot water in the tank splashing to the outside at a stretch and being burned by hot water.

  The fifth invention is particularly the fuel cell power generation system according to any one of the first to fourth inventions, wherein the fuel cell generates power and heat using hydrogen as the fuel gas and oxygen as the oxidant gas. By doing so, efficient power generation operation of the fuel cell can be performed.

  In particular, the sixth invention is a program for causing a computer to execute at least one of the fuel cell power generation systems of the first to fourth inventions. According to this configuration, since it is a program, a part or all of the fuel cell power generation system of the present invention can be easily realized using a microcomputer or the like. Further, the program can be easily distributed by recording it on a recording medium or distributing the program using a communication line.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, the thing of the same structure as background art attaches | subjects the same code | symbol, and abbreviate | omits description.

(Embodiment 1)
FIG. 1 is a system block diagram of the fuel cell power generation system according to the first embodiment, and FIG. 2 is a flowchart showing the main operation of the control means in the control device. Hereinafter, the configuration will be described.

  FIG. 1 is a system block diagram of a fuel cell power generation system according to the present invention. A fuel generator 1 generates a hydrogen-rich fuel gas by heating a raw material such as natural gas supplied from the outside in a steam atmosphere. . The fuel cell 2 is supplied with fuel gas generated by the fuel generator 1 and oxidant gas such as air through the blower 3. Although not shown, the direct current generated in the fuel cell 2 is converted into an alternating current by an inverter and then supplied to the external power load 4 in a grid connection with a commercial power source. On the other hand, the heat generated in the fuel cell 2 is supplied to an external heat load 5 such as hot water supply or heating as follows. The cooling water circulation pump 6 circulates the cooling water in the fuel cell 2 through the cooling water circulation path 7 and recovers heat in the heat exchange means 8 in order to recover the heat generated in the fuel cell 2. The hot water circulating pump 9 draws water having the lowest temperature in the hot water tank from the bottom of the hot water tank 10 that is full (in the city water) in advance, and recovers heat from the heat exchange means 8 through the hot water circulating circuit 11, Return to the upper part of the hot water tank 10. Thereby, the water in the hot water tank 10 is heated. The hot water obtained in this way (upper limit is about 70 ° C.) is used for the external heat load 5 such as hot water supply or heating, but by using the reheating means (backup hot water heater) 12 according to the user's temperature setting. Hot water (for example, boiling water) can be supplied to the heat load 5.

  The control device 18 has a control means 19 composed of a microcomputer and the like, and a water breakage detection means 17 for detecting the water breakage of the water supply to the hot water tank. The water breakage detection means 17 sequentially inputs the pressure in the water supply pipe with a sensor and the water pressure is increased. When 0.05 megapascal is divided, a water stop signal is output to the control means 19. The control device 18 is composed of these components, and while detecting the power consumption of the external power load 4 by the power load detection means 15, the fuel generator 1, the fuel cell 2, the blower 3, the cooling water circulation pump 6, the hot water circulation pump 9, etc. Are sequentially controlled.

  As described above, the operation of operating the cooling water circulation pump 6 and the hot water circulation pump 9 by the control means 14 and recovering the heat generated in the fuel cell 2 is an operation of cooling the fuel cell 2 in other words. Therefore, a series of functions for cooling the fuel cell 2 will be collectively referred to as the cooling means 16 hereinafter.

  The operation and action of the fuel cell power generation system configured as described above will be described below.

  After installing the fuel cell power generation system and completing the piping work for supplying the raw material (for example, city gas) and water to the fuel generator 1 and filling the hot water tank 10 in FIG. When the commercial power supply is energized, the control means (microcomputer) 19 is activated to start the system operation.

  As shown in the flowchart of FIG. 2, when the system operation is started, a startup process is started in S1, and the inside of the fuel generator 1 is raised to about 650 ° C. (which is a temperature at which fuel gas can be generated from the raw material gas). After the heating, the process proceeds to power generation processing (processing for generating power by supplying fuel gas and oxidant gas to the fuel cell 2) in S2. After that, the power generation operation is performed for half a day or more, and when the daily operation end scheduled time (for example, 8:00 pm) is reached in S3, or the user performs an operation end operation (not shown) from the operation operation panel. In this case, after the power generation end processing (post-processing for slowly cooling the fuel cell 2 in the high temperature state by the cooling means 16 in parallel with stopping the power generation) in S4, the system is in a standby state. To complete the series of system operations. Note that when the operation is started again after S4 is finished, it may be considered that the process returns to S1.

  On the other hand, when water breakage occurs during power generation, that is, when water breakage is detected by the water breakage detection means 17 in S5, an operation end command is output in S6, the power generation operation is stopped, and the cooling means 16 in S7. The maximum temperature of the hot water circulating pump 9 is maximized for about 10 minutes and the heat exchanging means 8 is rapidly cooled to reduce the internal temperature of the fuel cell 2 at a high temperature to 40 ° C. Lower to below. At the same time, the cooling effect can be further enhanced by maximizing the rotation speed of the cooling water circulation pump 6. Further, the cooling effect can be enhanced by increasing the number of rotations of the cooling water circulation pump 6 as compared with the normal operation.

  Although supplemented here, it is certainly desirable to cool the fuel cell 2 rapidly by indirectly cooling the heat exchanging means 8 shortly after the end of the power generation because the deterioration of the catalyst inside the fuel cell is promoted by the temperature change. However, compared with the degree of badness, the degree of badness is far greater than the fuel cell 2 cannot be sufficiently cooled by water shutoff (the fuel cell internal catalyst is oxidized by the oxidant gas when left at a high temperature). Therefore, the former method is used to further reduce the influence on the fuel cell 2 due to water outage.

  Thus, in the fuel cell power generation system having a stratified hot water storage tank that collects heat generated in the fuel cell 2 and stores the heat in the hot water storage tank 10, in the event of a water outage during power generation, the power generation operation is stopped. Then, the cooling means 16 is operated to the maximum, specifically, the hot water circulating pump 9 is operated at the maximum capacity, and the low temperature water is heated using the low temperature water at the lower part of the hot water tank 10 until it disappears. Thus, the fuel cell 2 can be rapidly cooled by 8 and the oxidation of the catalyst by the oxidant gas accumulated in the fuel cell 2 can be suppressed, so that the deterioration of the fuel cell 2 can be suppressed.

  In the present embodiment, the target temperature for raising the temperature of the fuel generator 1 at the time of startup and the fuel cell temperature at the time of cooling have been described with specific numerical values, but this does not limit the present invention.

(Embodiment 2)
FIG. 3 is a system block diagram of the fuel cell power generation system according to the second embodiment, and FIG. 4 is a flowchart showing the main operation of the control means in the control device. In the internal block diagram of the control device, reference numeral 20 denotes a residual heat amount detecting means for detecting the amount of hot water in the hot water tank, and specifically comprises a plurality of thermistors for detecting the temperature inside the hot water tank 10. Since it is possible to know how much hot water is present in the 200 liter capacity inside the tank 10, it is possible to know the remaining capacity of cold water necessary for cooling.

  The rest of the configuration is the same as that of the first embodiment except that the control device 21 and the control means 22 are indicated.

  The operation and action of the fuel cell power generation system configured as described above will be described below.

  As shown in the flowchart of FIG. 4, the only changes from the first embodiment of the present invention are the addition of S8 and S9. That is, when water breakage occurs during power generation, if water breakage is detected by the water breakage detection means 17 in S5, the remaining heat quantity Q is read from the remaining heat quantity detection means 20 in S8, and the remaining heat quantity Q is {40 ° C. * in S9. If it is less than 180 liters}, turning over, 20 liters of cold water lower than 40 ° C., which is the minimum required when power generation is stopped, is obtained by subtracting 180 liters from the 200 liter capacity of the hot water tank.

  As a result, it is possible to continue power generation while the minimum amount of cooling water (capacity) used for cooling during the stop process is secured, and short-time water outage occurs in the installation environment of the fuel cell power generation system. Even then, it will not stop power generation too sensitively.

(Embodiment 3)
FIG. 5 is a system block diagram of the fuel cell power generation system according to the third embodiment. In the internal block diagram of the control device, reference numeral 23 denotes a display for displaying the state of the fuel cell power generation system (operating state, error state, etc.). Means. The rest of the configuration is the same as that of the first embodiment except that the control device 24 and the control means 25 are indicated.

  The third embodiment is substantially the same as the first embodiment, and will be described with reference to the flowchart of FIG. 2. However, the water stop detection is detected by the display unit 23 of FIG. 5 at the timing when the water stop detection unit 17 detects the water stop in S5. An indication that an abnormal condition has been entered is displayed.

  This makes it possible to let the user know why the fuel cell power generation system has stopped, and when the external tap water pipe (water pipe to which city water is supplied) is rarely damaged. It is possible to notice an incident immediately.

(Embodiment 4)
FIG. 6 is a system block diagram of the fuel cell power generation system according to the fourth embodiment. In the internal block diagram of the control device, reference numeral 25 denotes stirring means for stirring hot water in the hot water tank, specifically a motor. A stirring blade is attached to the tip of the rotating shaft, and a flow of water (jet) is generated in the hot water tank 10 by repeating one-way or forward / reverse reversal. Water can be mixed forcibly. The rest of the configuration is the same as that of the first embodiment except that the control device 27 and the control means 28 are indicated.

  Since the fourth embodiment is almost the same as the first embodiment and will be described with reference to the flowchart of FIG. 2, the cooling operation by the cooling unit 17 in S7 is completed from the timing when the water stop detection unit 17 detects the water stop in S5. In the meantime, the stirring means 26 of FIG. 6 is operated continuously or intermittently.

  As a result, the hot water in the hot water tank 10 and the cold water in the hot water tank 10 are forcibly mixed, so that the hot water tank 10 falls over in a disaster and the hot water in the tank scatters to the outside at a stretch. It is possible to avoid dangerous situations such as

  As described above, the fuel cell power generation system according to the present invention can be used for a fuel cell cogeneration system that generates electric power using a fuel cell and uses exhaust heat to boil hot water to store and supply hot water.

  Similarly, for plant control in which dehydration occurs and the system goes down, it can also be applied to applications such as efficiently and effectively realizing cooling of high-temperature functional parts (actuators).

1 is a system block diagram of a fuel cell power generation system according to Embodiment 1 of the present invention. Operation flowchart of the control means 19 of Embodiment 1 of the present invention System block diagram of a fuel cell power generation system according to Embodiment 2 of the present invention Operation flowchart of the control means 22 according to the second embodiment of the present invention. System block diagram of a fuel cell power generation system according to Embodiment 3 of the present invention System block diagram of a fuel cell power generation system according to Embodiment 4 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel generator 2 Fuel cell 3 Blower (blower)
4 External Power Load 5 External Heat Load 6 Cooling Water Circulation Pump 7 Cooling Water Circulation Path 8 Heat Exchange Means 9 Hot Water Circulation Pump 10 Hot Water Storage Tank 11 Hot Water Circulation Path 12 Reheating Means 16 Cooling Means 17 Water Breakage Detection Means 18, 21 Controllers 19, 22 Control means 20 Residual heat detection means 23 Display means 26 Stirring means

Claims (6)

A fuel cell that generates electric power and heat using fuel gas and oxidant gas, heat exchange means for exchanging heat generated by the power generation of the fuel cell with hot water, and a hot water storage tank for storing hot water of the heat exchange means A hot water circulation path for circulating hot water in the hot water storage tank with heat exchange means, a hot water circulation pump for circulating hot water in the hot water circulation path, and the heat exchange means, hot water tank, hot water circulation path and hot water storage A fuel cell cooling means having a water circulation pump, a water cutoff detecting means for detecting water cutoff in the water supply to the hot water tank, and a control device for controlling at least the fuel cell and the cooling means, A fuel cell power generation system that stops power generation and operates the cooling means to the maximum when water breakage is detected by the water breakage detection means during power generation. It is provided with a remaining heat amount detecting means for detecting the amount of hot water in the hot water tank, and the control device continues the power generation operation until the remaining heat amount detected by the remaining heat amount detecting means reaches a predetermined value, and does not operate the cooling means. Item 4. The fuel cell power generation system according to Item 1. 2. The fuel cell power generation according to claim 1, further comprising display means for displaying a state of the fuel cell power generation system, wherein the control means displays on the display means that water breakage has occurred when water breakage is detected by the water breakage detection means. system. A stirring means for stirring hot water in the hot water tank is provided, and the control means controls the temperature in the hot water tank by the stirring means when water shutoff is detected by the water shutoff detecting means. 2. A fuel cell power generation system according to item 1. The fuel cell power generation system according to any one of claims 1 to 4, wherein electric power and heat are generated using hydrogen as a fuel gas and oxygen as an oxidant gas. The program for making a computer perform at least 1 means in the fuel cell power generation system of any one of Claims 1-4.

Images