JP2010040349A - Fuel cell cogeneration system, its control method, and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell cogeneration system capable of preventing propagation of various germs in a hot water tank and capable of operating normally fuel cell power generation at a low cost without adding a device such as a boiler and a radiator, its control method, and a control program. <P>SOLUTION: The fuel cell cogeneration system comprises a hot water tank 1 which accumulates exhaust heat from a fuel cell F by heat exchange through an exhaust heat recovering line L1, a heater 5 installed on the exhaust heat recovering line L1, a thermometer 2 which is installed at a position capable of judging whether a water flow-rate required for cooling the fuel cell F is secured or not in the hot water tank 1, a setting memory part 32 which stores a prescribed temperature, a judgement part 33 which judges whether or not the temperature measured by the thermometer 2 has risen to a prescribed temperature or more at the time of heating by the heater 5, and a shutdown instruction part 34 which shuts down the fuel cell F when it is judged to have risen to the prescribed temperature or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell cogeneration system, a control method thereof, and a control program in which a bacterial propagation prevention function is improved in a hot water tank for recovering exhaust heat of a fuel cell.

  A fuel cell is a power generator that supplies a fuel gas, such as hydrogen, and an oxidant gas, such as air, to the cell body to cause an electrochemical reaction, converting the chemical energy of the fuel directly into electrical energy and taking it out. Device. This fuel cell has been evaluated as a power generation device that has high power generation efficiency and is excellent in environmental performance with less pollutant emission and noise.

  For example, a fuel cell that is expected as a home-use distributed power source is required to have a system that uses city gas or LPG, which is easily available and has a high methane component, as fuel gas. In this case, it is necessary to reform the fuel gas to hydrogen. For this purpose, a method using a fuel processor that generates hydrogen-rich gas by mixing water vapor with the fuel gas is generally used.

  And a household fuel cell system is normally comprised as a cogeneration system using exhaust heat. This exhaust heat utilization method generates hot water by heat exchange with exhaust heat, accumulates it in a hot water storage tank, and supplies the accumulated hot water from the hot water storage tank according to the heat usage at home of the installation destination. This is common.

  By the way, if the hot water accumulated in the hot water storage tank stays for a long time, there is a possibility that germs will propagate. Therefore, before the breeding condition is reached, an operation for preventing miscellaneous bacteria propagation is performed. For example, the propagation of germs is prevented by heating and raising the temperature of hot water in the hot water tank.

To heat the hot water in the hot water tank, a boiler or heater as a heating source is installed on a circulation line provided in the hot water tank, and the hot water in the hot water tank is regularly heated to a high temperature by this heating source. A method of heating the entire hot water tank to a set temperature or higher by circulating it while being well known is well known. For example, Patent Document 1 discloses a technique for preventing the propagation of germs by heating hot water in a hot water tank using a boiler.
JP 2007-3075 A

  In the fuel cell cogeneration system, various facilities for heat exchange are required in addition to facilities for fuel cell power generation. For this reason, the cost of the entire apparatus tends to be high. Therefore, there is a strong demand for suppressing an increase in extra costs.

  However, in a system in which hot water is heated using a boiler, a boiler is required, which increases costs. In a configuration in which an inexpensive heater is used instead of a boiler, the heater output is generally small, so that heating of only the heater increases the time for raising the hot water temperature of the entire hot water tank to the set temperature. For this reason, it is necessary to install a heater on the exhaust heat recovery line of the fuel cell, to generate power from the fuel cell in combination with the heating of the heater, and to heat the hot water together with the exhaust heat of the fuel cell.

  However, in the exhaust heat recovery line, the return water from the hot water tank to the fuel cell is used as cooling water for the fuel cell. For this reason, when the temperature of the hot water tank rises due to the heating of the hot water tank described above, it becomes difficult to properly cool the fuel cell.

  In order to cope with this, a radiator that cools with outside air etc. is installed on the return line from the hot water tank to the fuel cell, and when the return temperature rises above the set value, the radiator is operated and the return temperature falls below the set value. Measures were taken to reduce it.

  However, in such a configuration, it is necessary to add a radiator for preventing an increase in the return temperature, so that the cost is also increased, and there is a possibility that reliability is reduced due to an increase in parts.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and its purpose is to allow propagation of various germs in a hot water tank without adding a device such as a boiler or a radiator. It is an object of the present invention to provide a fuel cell cogeneration system, a control method thereof, and a control program that can be prevented and that can normally operate fuel cell power generation at low cost.

  In order to achieve the above object, the present invention has a hot water storage tank for accumulating exhaust heat from a fuel cell by heat exchange via an exhaust heat recovery line, and a heater provided on the exhaust heat recovery line. In the fuel cell cogeneration system, during the operation of the fuel cell for preventing bacterial growth and the heating by the heater, the fuel cell does not secure a water flow rate necessary for cooling the fuel cell in the hot water tank. It has the control device which stops.

  In the present invention as described above, the stop operation can be performed before the hot water in the hot water tank is completely heated and the cold heat source necessary for stopping the fuel cell cannot be accumulated. For this reason, it is possible to prevent deterioration in performance while preventing miscellaneous bacteria breeding in the hot water storage tank at low cost without adding a device such as a boiler or a radiator.

  As a more specific aspect of the fuel cell cogeneration system, a thermometer installed at a lower part of the hot water tank, a storage unit for storing a predetermined temperature, and when heated by the heater, are measured by the thermometer. A determination unit that determines whether the temperature has risen above a predetermined temperature, and a stop instruction unit that stops the fuel cell when the determination unit determines that the temperature has increased above a predetermined temperature; It is characterized by having.

  In the present invention as described above, the temperature of the lower layer of the hot water tank is measured, and the hot water in the hot water tank is completely heated by stopping the fuel cell when the temperature reaches a predetermined temperature, which is necessary for stopping the fuel cell. The stop operation can be performed before the cold source can no longer accumulate. For this reason, it is possible to prevent deterioration in performance while preventing miscellaneous bacteria breeding in the hot water storage tank at low cost without adding a device such as a boiler or a radiator.

  According to the present invention as described above, it is possible to prevent the propagation of various bacteria in the hot water tank without adding a device such as a boiler or a radiator, and to normally operate the fuel cell power generation at a low cost. A possible fuel cell cogeneration system, its control method and control program can be provided.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be specifically described with reference to the drawings.
(1) First Embodiment (1-1) Configuration In this embodiment, as shown in FIG. 1, a fuel cell F, a hot water tank 1, a thermometer 2, a control device 3, a hot water pump 4, a heater 5 and the like are provided. Have. The fuel cell F generates power by receiving supply of a fuel gas such as hydrogen and an oxidant gas such as air, and includes any fuel cell that can be used now or in the future. In the figure, Fa is a heat exchange part in the cooling water passage inside the fuel cell F.

  The fuel cell F is provided with an exhaust heat recovery line L1 through which hot water circulates through heat exchange between cooling water and exhaust heat in the heat exchanging section Fa. The hot water storage tank 1 is a tank that heats, accumulates and supplies tap water by heat exchange with warm water in the exhaust heat recovery line L1. A tap water supply line L2 for supplying tap water and a hot water supply line L3 for supplying hot water are connected to the hot water tank 1.

The thermometer 2 is provided in the hot water tank 1 in order to measure the temperature in the hot water tank 1. In the present embodiment, as will be described later, the temperature in the hot water tank 1 is measured, and the fuel cell F is stopped before the amount of low-temperature hot water becomes equal to or less than the water flow rate required for cooling when the fuel cell F is stopped. In order to be able to do so, the installation position of the thermometer 2 is set as follows. Usually, it becomes the lower part of the hot water tank 1.

Volume from the location of the thermometer to the bottom of the hot water tank> Total coolant flow required to cool the fuel cell

  The control device 3 is means for controlling the operation of the fuel cell F based on the temperature measured by the thermometer 2 as will be described later. The hot water pump 4 is a device that circulates the hot water in the exhaust heat recovery line L1. The heater 5 is means for heating the hot water in the exhaust heat recovery line 11.

  As illustrated in FIG. 2, the control device 3 includes an input unit 31, a setting storage unit 32, a determination unit 33, and a stop instruction unit 34. The input unit 31 is a unit that converts the measurement signal from the thermometer 2 into a format suitable for determination by the determination unit 33 and inputs it. The setting storage unit 32 is a unit that stores in advance various settings necessary for the processing of the embodiment, such as a predetermined temperature serving as a threshold value for determination by the determination unit 33. This predetermined temperature is, for example, the upper limit of the water temperature necessary for cooling the fuel cell F.

  The determination unit 33 is a unit that determines whether or not the measured temperature is equal to or higher than a predetermined temperature based on the measured temperature input from the input unit 31 and the temperature set in the setting storage unit 32. The stop instruction unit 34 is a means for outputting a stop instruction of the fuel cell F when the determination unit 33 determines that the measured temperature is equal to or higher than a predetermined temperature.

  The control device 3 can be realized by, for example, a dedicated electronic circuit or a computer that operates with a predetermined program. Therefore, a computer program for controlling the operation of the apparatus according to the procedure described below and a recording medium recording the computer program are also one aspect of the present invention.

(1-2) Operation The operation of the present embodiment having the above-described configuration is as follows. That is, in order to prevent sterilization and propagation, the fuel cell F is supplied with fuel gas and oxidant gas (not shown) to generate power, and the heater 5 and the fuel cell F installed on the exhaust heat recovery line L1. The hot water in the hot water storage tank 1 is raised to a set temperature using the exhaust heat of. At this time, the internal hot water temperature of the hot water tank 1 rises from the upper part toward the lower part. The fuel cell F is cooled by the return water from the hot water storage tank 1 of the exhaust heat recovery line L1.

  Here, while the heating of the hot water tank 1 does not proceed to a specific position (the limit position where the cooling water flow rate is ensured), the return temperature from the hot water tank 1 is low, so that the fuel cell F can be operated. However, when the temperature rises to a specific position in the hot water tank 1, the above cooling function is lost, and normal operation of the fuel cell F becomes difficult. In addition, a cooling heat source is also required in the process of stopping the fuel cell F. However, if there is no cooling source during the stop operation, there is a possibility that an irreversible influence may occur on the fuel cell F.

  For example, FIG. 3 shows an example of the operation of the fuel cell F, the amount of hot water in the hot water tank 1 due to the heating of the heater 5, and the temperature characteristics of the upper and lower parts of the hot water tank 1. According to FIG. 2, at the start of operation, the hot water temperature in the hot water tank 1 rises due to the operation of the fuel cell F and the heating of the heater 5. The return temperature at which the fuel cell F is cooled does not rise until just before 7 hours when the heating is completed.

  However, even if the stop operation of the fuel cell F is performed after the return temperature starts to rise, it is difficult to perform an appropriate stop operation because the return temperature rises quickly. Therefore, in this embodiment, the temperature of the lower part in the hot water tank 1 is measured by the thermometer 2. The measured temperature is input from the input unit 31 to the determination unit 33. The determination unit 33 determines whether or not the measured temperature is equal to or higher than a predetermined temperature.

  When the determination unit 33 determines that the measurement temperature has become equal to or higher than the predetermined temperature, the stop instruction unit 34 assumes that the heating in the hot water tank 1 is approaching the limit position where the cooling water flow rate is secured. An instruction to stop the operation of the fuel cell F is output. For example, power generation is stopped by stopping the supply of fuel gas and oxidant gas. As described above, the operation of stopping the fuel cell F is performed before the cold heat source necessary for stopping the fuel cell F cannot be accumulated in the hot water storage tank 1.

(1-3) Effect According to the present embodiment as described above, the temperature in the hot water tank 1 is monitored when the power generation operation of the fuel cell F is performed in order to prevent the proliferation of hot water in the hot water tank 1. Thus, the fuel cell F can be stopped before the hot water in the hot water tank 1 is completely heated and the cold heat source is insufficient. For this reason, without adding a boiler, a radiator, etc., the performance deterioration of the fuel cell F can be prevented while preventing germs breeding in the hot water tank 1 at low cost.

(2) Second Embodiment (2-1) Configuration The present embodiment basically has the same configuration as that of the first embodiment. However, in this embodiment, as shown in FIG. 4, the control device 3 is configured to perform control based on the number of rotations of the hot water pump 4. More specifically, as shown in FIG. 5, the control device 3 includes a hot water supply amount calculation unit 35 that calculates the hot water supply amount to the hot water tank 1 from the number of rotations of the hot water pump 4, and the calculated hot water supply amount. On the basis of the above, a heated hot water amount calculation unit 36 for calculating the heated hot water amount is provided.

  Moreover, the determination part 33 has a function which determines whether the amount of hot water heated approached the limit amount with which a cooling water flow volume is ensured. The setting storage unit 32 stores in advance various settings necessary for the processing of the embodiment, such as a predetermined amount of hot water serving as a threshold value for determination by the determination unit 33, a reference for calculation by the calculation unit, and the like. Yes.

(2-2) Operation The operation of the present embodiment having the above-described configuration is as follows. That is, as in the first embodiment, in order to prevent the propagation of germs in the hot water tank 1, the hot water tank 1 is used by using the exhaust heat of the heater 5 and the fuel cell F installed on the exhaust heat recovery line L1. Raise the hot water to the set temperature. And the hot water supply amount calculating part 35 calculates the hot water supply amount to the hot water storage tank 1 based on the rotation speed of the hot water pump 4 that supplies hot water. Based on this hot water supply amount, the heated hot water amount calculation unit 36 calculates the amount of hot water heated inside the hot water tank 1.

  The determination unit 33 determines whether or not the calculated amount of heated hot water is equal to or greater than a predetermined amount of hot water. If it is determined that the predetermined amount of hot water has been reached, the stop instructing unit 34 determines that the amount of low-temperature hot water in the hot water tank 1 has approached the limit of the amount necessary for stopping the fuel cell F, and operates the fuel cell F. Outputs an instruction to stop. As described above, the operation of stopping the fuel cell F is performed before the cold heat source necessary for stopping the fuel cell F cannot be accumulated in the hot water storage tank 1.

(2-3) Effect According to the present embodiment as described above, the rotational speed of the hot water pump 4 is monitored when the power generation operation of the fuel cell F is performed in order to prevent the proliferation of hot water in the hot water tank 1. Thus, the amount of heated hot water in the hot water tank 1 is obtained, and the fuel cell F can be stopped before the hot water in the hot water tank 1 is completely heated and the cold heat source is insufficient. For this reason, without adding a boiler, a radiator, etc., the performance deterioration of the fuel cell F can be prevented while preventing the propagation of germs in the hot water tank 1 at a low cost.

(3) Third Embodiment (3-1) Configuration This embodiment basically has the same configuration as that of the first embodiment. However, in the present embodiment, as shown in FIG. 6, a flow meter 6 that measures the amount of hot water is installed in the exhaust heat recovery line L <b> 1, and the control device 3 controls the amount of hot water supplied by the flow meter 6. It is configured to perform control based on. More specifically, as shown in FIG. 7, the control device 3 includes a heated hot water amount calculation unit 36 that calculates the amount of heated hot water based on the measured hot water supply amount.

  Moreover, the determination part 33 has a function which determines whether the amount of heated hot water has reached the limit amount with which a cooling water flow volume is ensured. The setting storage unit 32 stores in advance various settings necessary for the processing of the embodiment, such as a predetermined amount of hot water serving as a threshold value for determination by the determination unit 33, a reference for calculation by the calculation unit, and the like. Yes.

(3-2) Operation The operation of the present embodiment having the above-described configuration is as follows. That is, as in the first embodiment described above, in order to prevent the propagation of germs in the hot water tank 1, the heater 5 installed on the exhaust heat recovery line L1 and the exhaust heat of the fuel cell are used. Raise the hot water to the set temperature. Based on the hot water supply amount measured by the flow meter 6, the heated hot water amount calculation unit 36 calculates the amount of hot water heated inside the hot water tank 1.

  The determination unit 33 determines whether or not the calculated amount of heated hot water is equal to or greater than a predetermined amount of hot water. If it is determined that the predetermined amount of hot water has been reached, the stop instructing unit 34 determines that the amount of low-temperature hot water in the hot water tank 1 has approached the limit of the amount necessary for stopping the fuel cell F, and operates the fuel cell F. Outputs an instruction to stop. As described above, the operation of stopping the fuel cell F is performed before the cold heat source necessary for stopping the fuel cell F cannot be accumulated in the hot water storage tank 1.

(3-3) Effect According to the present embodiment as described above, when the power generation operation of the fuel cell F is performed to prevent miscellaneous propagation of hot water in the hot water tank 1, the amount of hot water supplied is monitored, and the hot water tank The amount of heated hot water in 1 is obtained, and the fuel cell F can be stopped before the hot water in the hot water storage tank 1 is completely heated and the cold heat source becomes insufficient. For this reason, without adding a boiler, a radiator, etc., the performance deterioration of the fuel cell F can be prevented while preventing the propagation of germs in the hot water tank 1 at a low cost.

(4) Other Embodiments The present invention is not limited to the above embodiment. For example, more precise control may be performed by combining the first embodiment and the second embodiment, or by combining the first embodiment and the third embodiment. That is, it is free to configure the embodiment by combining any of the claims in the present invention.

  Various settings such as the installation position of the thermometer, the predetermined temperature, the predetermined amount of hot water, etc. can be freely set, and may be a numerical value with a certain margin so that the processing is performed before the limit value. For example, it is important to install the thermometer at an appropriate position in consideration of the stop time and the return temperature rise time. Further, it is free to determine whether the determination includes a threshold (above or less) or does not include (greater than or less than). Therefore, “above” in the claims is merely a convenient expression and includes a determination that does not include a threshold value.

  In addition, the configuration of the cogeneration system to which the present invention is applied is not limited to that exemplified in the above-described embodiment, and what is adopted as each component or not is free.

The block diagram which shows 1st Embodiment of the fuel cell cogeneration system of this invention Functional block diagram showing the control device of the embodiment of FIG. Explanatory drawing which shows an example of the heat characteristic in the hot water storage tank by the exhaust heat of a fuel cell and a heater, and the temperature characteristic of the upper part and lower part of a hot water storage tank. The block diagram which shows 2nd Embodiment of the fuel cell cogeneration system of this invention. Functional block diagram showing the control device of the embodiment of FIG. The block diagram which shows 3rd Embodiment of the fuel cell cogeneration system of this invention Functional block diagram showing the control device of the embodiment of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hot water storage tank 2 ... Thermometer 3 ... Control apparatus 4 ... Hot water pump 5 ... Heater 6 ... Flow meter 31 ... Input part 32 ... Setting memory | storage part 33 ... Determination part 34 ... Stop instruction | indication part 35 ... Hot water supply amount calculating part 36 ... Heated hot water amount calculation unit

Claims (7)

In a fuel cell cogeneration system having a hot water storage tank for accumulating exhaust heat from a fuel cell by heat exchange through an exhaust heat recovery line, and a heater provided on the exhaust heat recovery line,
A controller for stopping the fuel cell before the water flow rate required for cooling the fuel cell is not secured in the hot water storage tank during operation of the fuel cell for preventing bacterial growth and heating by the heater; A fuel cell cogeneration system. In a fuel cell cogeneration system having a hot water storage tank for accumulating exhaust heat from a fuel cell by heat exchange through an exhaust heat recovery line, and a heater provided on the exhaust heat recovery line,
In the hot water storage tank, a thermometer installed at a position where it can be determined whether or not a water flow rate necessary for cooling the fuel cell is secured;
A storage unit for storing a predetermined temperature;
A determination unit that determines whether or not the temperature measured by the thermometer has risen above a predetermined temperature during operation of the fuel cell for preventing bacterial growth and heating by the heater;
A stop instruction unit that stops the fuel cell when the determination unit determines that the temperature has risen to a predetermined temperature or higher;
A fuel cell cogeneration system comprising: In a fuel cell cogeneration system having a hot water storage tank for accumulating exhaust heat from a fuel cell by heat exchange through an exhaust heat recovery line, and a heater provided on the exhaust heat recovery line,
A thermometer installed at the bottom of the hot water tank;
A storage unit for storing a predetermined temperature;
A determination unit that determines whether or not the temperature measured by the thermometer has risen above a predetermined temperature during operation of the fuel cell for preventing bacterial growth and heating by the heater;
A stop instruction unit that stops the fuel cell when the determination unit determines that the temperature has risen above a predetermined temperature;
A fuel cell cogeneration system comprising: A hot water storage tank that accumulates exhaust heat from the fuel cell by heat exchange through the exhaust heat recovery line, a heater provided on the exhaust heat recovery line, a hot water pump that circulates hot water through the exhaust heat recovery line, and In a fuel cell cogeneration system having
A storage unit for storing a predetermined amount of hot water;
A heating water amount calculation unit that calculates the amount of hot water inside the hot water tank based on the number of rotations of the hot water pump during operation of the fuel cell and prevention of bacterial growth and heating by the heater;
A determination unit for determining whether or not the amount of heated hot water calculated by the amount of heated hot water calculation unit is equal to or greater than a predetermined amount of hot water;
A stop instruction unit that stops the fuel cell when the determination unit determines that the amount of hot water is equal to or greater than a predetermined amount;
A fuel cell cogeneration system comprising: A hot water storage tank that accumulates exhaust heat from the fuel cell by heat exchange through the exhaust heat recovery line, a heater provided on the exhaust heat recovery line, and a flow meter that measures the amount of hot water in the exhaust heat recovery line; In a fuel cell cogeneration system having
A heated hot water amount calculation unit that calculates the amount of heated hot water inside the hot water storage tank based on the hot water supply amount measured by the flow meter during operation of the fuel cell for preventing bacterial growth and heating by the heater;
A determination unit that determines whether or not the amount of heated hot water calculated by the amount of heated hot water calculation unit is equal to or greater than a predetermined amount of hot water;
A stop instruction unit that stops the fuel cell when the determination unit determines that the amount of hot water is equal to or greater than a predetermined amount;
A fuel cell cogeneration system comprising: A fuel cell cogeneration system having a hot water storage tank for accumulating exhaust heat from a fuel cell by heat exchange through an exhaust heat recovery line, and a heater provided on the exhaust heat recovery line, using a computer or an electronic circuit In the control method to control,
When the computer or the electronic circuit operates the fuel cell for preventing bacterial growth and is heated by the heater, the fuel cell does not secure a water flow rate necessary for cooling the fuel cell in the hot water tank. A control method for a fuel cell cogeneration system, characterized in that A fuel cell cogeneration system having a hot water storage tank for accumulating exhaust heat from the fuel cell by heat exchange through the exhaust heat recovery line, and a heater provided on the exhaust heat recovery line for preventing germ growth In a control program controlled by a computer,
In the computer,
During operation of the fuel cell for preventing bacterial growth and heating by the heater, the fuel cell is stopped before the water flow rate necessary for cooling the fuel cell is not secured in the hot water tank. Control program for fuel cell cogeneration system.

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