JP6558578B2 - Cogeneration system, fuel cell system, and operation method of fuel cell system - Google Patents

Description

  The present invention relates to a cogeneration system, a fuel cell system, and a method for operating the fuel cell system.

  As an example of a conventional cogeneration system, a fuel cell system that generates electric power and heat by a fuel cell and stores this heat as hot water in a hot water storage tank is known. For example, 60 ° C. hot water is stored in a hot water storage tank. However, when the hot water temperature of the hot water storage tank is lowered to about 50 ° C. due to heat radiation or the like, it is said that germs such as Legionella bacteria easily propagate in the hot water storage tank.

  On the other hand, in the cogeneration system of Patent Document 1, when the amount of hot water supplied from the hot water storage tank to the outside within a predetermined period is equal to or less than a predetermined value, a valve provided in the hot water pipe is closed to store the hot water. The valve is opened after the fuel cell is operated so that the entire inside of the tank reaches a predetermined temperature or higher. Thereby, when the water in a hot water tank is hardly used over a long period of time, supply of the warm water to the exterior from the hot water tank is temporarily stopped. At the time of this stop, the fuel cell is operated, the water in the hot water tank is warmed by the heat generated at that time, and the water in the hot water tank and the hot water tank is sterilized.

JP2007-248010A

  However, the prior art described in Patent Document 1 still has room for improvement from the viewpoint of cost. This invention solves such a problem, and it aims at providing the cogeneration system in which appropriate hot water supply and a sterilization process are possible, suppressing the raise in cost.

  A cogeneration system according to an aspect of the present invention includes a power generator that generates power, a first heat exchanger that performs heat exchange between exhaust heat from the power generator and cooling water, and a hot water storage tank in which hot water is stored. A second heat exchanger for exchanging heat between the cooling water and the hot water, a circulation path for circulating the cooling water between the first heat exchanger and the second heat exchanger, and the circulation path A circulation pump that circulates the cooling water, a temperature detector that is provided in the circulation path upstream from the first heat exchanger and downstream from the second heat exchanger, and that detects the temperature of the cooling water, and a control The controller has a second predetermined time when the time during which the power generation is not continuously performed reaches a first predetermined time or when the hot water supply is not continuously performed. When the time is reached, the hot water supply prohibition mode that does not allow the supply of hot water is not allowed. When the power generation is performed, the flow rate of the cooling water is decreased by the circulation pump, and the hot water supply prohibition mode is canceled when the temperature detected by the temperature detector reaches the first predetermined temperature. .

  In the cogeneration system, the present invention has an effect that appropriate hot water supply and sterilization can be performed while suppressing an increase in cost.

  The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.

It is a block diagram which shows roughly the functional structure of the cogeneration system which concerns on 1st Embodiment. It is a flowchart which shows an example of the operating method of the cogeneration system of FIG. It is a flowchart which shows an example of the operation method of the cogeneration system which concerns on 2nd Embodiment. It is a flowchart which shows an example of the operating method of the cogeneration system which concerns on 3rd Embodiment. It is a block diagram which shows roughly the functional structure of the cogeneration system which concerns on 4th Embodiment. It is a flowchart which shows an example of the operating method of the cogeneration system of FIG. It is a flowchart which shows an example of the operating method of the cogeneration system which concerns on 5th Embodiment. 8A to 8C are block diagrams schematically showing a part of the functional configuration of the cogeneration system according to the sixth embodiment. 9A and 9B are block diagrams schematically showing a part of the functional configuration of the cogeneration system according to the seventh embodiment. It is a block diagram which shows roughly a part of functional structure of the cogeneration system which concerns on 8th Embodiment. It is a block diagram which shows roughly the functional structure of the fuel cell system which concerns on 9th Embodiment. It is a flowchart which shows an example of the operating method of the fuel cell system system of FIG.

(Knowledge that is the basis of the present invention)
The inventors of the present invention have intensively studied the cogeneration system in order to appropriately perform hot water supply and sterilization while suppressing increase in cost. As a result, the present inventors have found that the prior art has the following problems.

  That is, in the cogeneration system of Patent Document 1, clean water is supplied to the hot water storage tank through a water supply pipe, and is circulated between the hot water storage tank and the heat exchanger through a heat recovery pipe. Such tap water is generally tap water and contains metal ions such as calcium and magnesium. For this reason, when clean water is heated with a heat exchanger, metal oxide (scale) is easily generated by metal ions in clean water. And if a scale accumulates on a heat exchanger and heat recovery piping, problems, such as a fall of heat exchange efficiency, will arise. In response to the problem of scale, for example, if piping that does not easily adhere to the scale is used, the cost of the system increases.

  Moreover, in order to suppress generation | occurrence | production of a scale, it is possible not to use the water of a hot water tank like patent document 1, but to use a heat medium other than this for the medium heated with a heat exchanger. In this case, the heat medium circulates through the heat recovery pipe and exchanges heat with the water in the hot water tank. However, if the heat quantity of the heat medium flowing into the hot water tank is larger than the heat quantity that can be transferred per unit time in the hot water tank, and the heat exchange between the water in the hot water tank and the heat medium is not sufficiently performed, It is discharged from the hot water tank in a state where the temperature is higher than the temperature of the water in the hot water tank. In such a case, since the water temperature of the hot water tank is lower than the temperature of the heat medium, when the water temperature of the hot water tank is determined based on the temperature of the heat medium, the water temperature of the entire hot water tank is high enough to be sterilized. It cannot be detected accurately and the water in the hot water tank cannot be properly sterilized.

  For this reason, in the cogeneration system of patent document 1, in order to measure the temperature in a hot water storage tank, the temperature sensor is provided in the upper part and the lower part of the hot water storage tank. With this temperature sensor, it can be confirmed whether the temperature in the hot water storage tank is a temperature at which sterilization is possible. However, since a dedicated temperature sensor for measuring the temperature in the hot water tank is provided, the cost increases.

  Therefore, the present inventors adjust the flow rate of the heat medium that exchanges heat with the water in the hot water tank, and use a temperature detector that detects the temperature of the heat medium downstream from the hot water tank to detect the water temperature of the hot water tank. It has also been found that appropriate hot water supply and sterilization can be performed while suppressing an increase in cost by also using as a vessel. The present invention has been made based on this finding.

  In the cogeneration system according to the first embodiment of the present invention, a generator that generates electric power, a first heat exchanger that exchanges heat between the exhaust heat from the generator and cooling water, and hot water are stored. A hot water storage tank, a second heat exchanger that exchanges heat between the cooling water and the hot water, a circulation path through which the cooling water circulates between the first heat exchanger and the second heat exchanger, A circulation pump that circulates the cooling water in the circulation path; and a temperature detector that is provided in the circulation path upstream of the first heat exchanger and downstream of the second heat exchanger and detects the temperature of the cooling water. And a controller, wherein the controller has a time when the power generation is not continued for a first predetermined time, or a time when the hot water is not continuously supplied. No hot water supply allowed to supply hot water when the second predetermined time is reached When the mode is set and the power generation is performed, the flow rate of the cooling water is reduced by the circulation pump, and the hot water supply prohibition mode is canceled when the temperature detected by the temperature detector reaches the first predetermined temperature. To do.

  According to this configuration, when the time during which power generation is not continuously performed reaches the first predetermined time, or when the time during which supply of hot water is not continuously performed reaches the second predetermined time, the sterilization is performed. Is determined to be necessary. In such a case, the hot water storage water is not supplied by setting the hot water supply prohibition mode.

  In this hot water supply prohibition mode, by reducing the flow rate of the cooling water by the circulation pump, the heat quantity of the cooling water is changed from the cooling water to the stored hot water in the second heat exchanger as compared with the case where the flow rate of the cooling water is not reduced. The amount of heat that can be transferred per unit time can be approached. That is, heat exchange between the hot water and the cooling water in the second heat exchanger is sufficiently performed. Moreover, since the temperature of the cooling water that has flowed out of the second heat exchanger over a longer time can be brought close to the temperature of the hot water, the temperature of the hot water can be determined from the detected temperature of the cooling water. That is, there is no need to provide a temperature detector dedicated to hot water, and it is possible to more accurately detect that the temperature of the hot water has risen to a high enough temperature to sterilize, while suppressing an increase in cost. Can be sterilized appropriately.

  Furthermore, when the temperature detected by the temperature detector reaches the first predetermined temperature, the hot water supply prohibition mode is canceled. Thereby, the sterilized hot water can be supplied, and an appropriate hot water supply is realized.

  Moreover, hot water storage is not used for the cooling water which exchanges heat with exhaust heat in the first heat exchanger. For this reason, even if the cooling water is heated by the first heat exchange, generation of scale due to metal ions contained in the hot water storage is prevented. Therefore, it is not necessary to use an expensive member for preventing the scale from adhering to the first heat exchanger due to the scale, and an increase in cost can be suppressed.

  The cogeneration system according to a second aspect of the present invention is the cogeneration system according to the first aspect, wherein the controller reduces the output of the power generation when the power generation is being performed, and the cooling by the circulation pump. The flow rate of water may be reduced.

  According to this structure, the temperature change of the cooling water after the heat exchange in the first heat exchanger is reduced by reducing the amount of exhaust heat due to the decrease in the output of the generator. For this reason, the temperature change of the hot water and the cooling water after the heat exchange in the second heat exchanger can be reduced, and the temperature of the cooling water that has passed through the second heat exchanger for a longer time can be made closer to the temperature of the hot water. it can.

  The cogeneration system according to a third aspect of the present invention is the cogeneration system according to the first or second aspect, wherein the controller performs the power generation at a rated output when the power generation is performed, The output of power generation may be reduced, and the flow rate of the cooling water may be reduced by the circulation pump.

  According to this configuration, the amount of exhaust heat increases due to the power generation of the rated output, and the temperature of the cooling water heated by the exhaust heat in the first heat exchanger increases. For this reason, since the amount of heat transfer between the high-temperature cooling water and the hot water in the second heat exchanger increases, the hot water can be heated to the first predetermined temperature in a short time, and the time until the hot water supply prohibition mode is released is shortened. Is achieved.

  A cogeneration system according to a fourth aspect of the present invention is provided in the circulation path upstream of the first heat exchanger and downstream of the second heat exchanger in any one of the first to third aspects. And a radiator for radiating the cooling water, wherein the temperature detector is provided in the circulation path upstream of the first heat exchanger and downstream of the radiator, and the controller performs the power generation. The heat dissipation by the radiator is started, the output of the power generation is decreased, the flow rate of the cooling water is decreased by the circulation pump, and the amount of heat dissipation by the radiator is decreased or the heat dissipation is stopped. You may let them.

  According to this configuration, the temperature of the cooling water flowing into the first heat exchanger is reduced by radiating the cooling water. For this reason, since the exhaust heat is cooled by the cooling water in the first heat exchanger, it is possible to prevent high-temperature exhaust heat from being discharged outside the system.

  Moreover, the fall of the temperature of the cooling water after passing a heat radiator by the fall of the heat dissipation amount or the stop of heat dissipation reduces. For this reason, the detected temperature of the cooling water can be brought close to the temperature of the stored hot water, and the detected temperature can be used to determine the temperature of the stored hot water.

  The cogeneration system according to a fifth aspect of the present invention is the cogeneration system according to any one of the first to fourth aspects, wherein the controller has a third elapsed time after the detected temperature reaches the first predetermined temperature. After reaching a predetermined time, the hot water supply prohibition mode may be canceled. According to this configuration, since the state where the temperature of the hot water is equal to or higher than the first predetermined temperature is maintained for the third predetermined time, the hot water can be sterilized more reliably.

  In the cogeneration system according to a sixth aspect of the present invention, in any one of the first to fifth aspects, the second heat exchanger is provided in the hot water storage tank, and the cooling water is the second heat. You may distribute | circulate from the upper part of the said hot water storage tank to the lower part in the exchanger.

  According to this configuration, the cooling water flows in from the upper part of the hot water storage tank, exchanges heat with the hot water storage in the second heat exchanger, and flows out at a temperature close to the temperature of the hot water storage in the lower part of the hot water storage tank. For this reason, the temperature of the low temperature hot water stored in the lower part of the hot water storage tank can be determined based on the detected temperature of the cooling water. The temperature of this hot water is lower at the bottom of the hot water tank. Therefore, if the detected temperature has reached the first predetermined temperature, the temperature of the upper part of the stored hot water is equal to or higher than the first predetermined temperature, and it can be determined that the entire stored hot water has reached the first predetermined temperature. It is possible to cancel the hot water supply prohibition mode more appropriately.

  A cogeneration system according to a seventh aspect of the present invention is the cogeneration system according to any one of the first to sixth aspects, wherein a hot water supply path for supplying the hot water from the hot water storage tank and a water supply for supplying clean water to the hot water storage tank are provided. A path, and an opening / closing valve provided on at least one of the hot water supply path or the water supply path and opening / closing the hot water supply path or the water supply path, the controller does not allow the opening / closing valve to be opened, The hot water supply prohibition mode may be set. According to this configuration, by not permitting the opening / closing of the on-off valve, the hot water supply path or the water supply path is closed, and hot water from the hot water storage tank is prohibited.

  A cogeneration system according to an eighth aspect of the present invention, in any one of the first to sixth aspects, is connected to a hot water supply path for supplying the hot water from the hot water storage tank, the hot water storage tank, and the hot water supply path. The controller includes: a water supply path for supplying clean water to the hot water storage tank; and a mixing valve provided at a connection point between the hot water supply path and the water supply path to open and close the hot water supply path and the water supply path. The hot water supply prohibition mode may be set without allowing the hot water supply path to be opened by the mixing valve. According to this configuration, the hot water supply path is closed by not permitting the hot water supply path to be opened by the mixing valve, and hot water from the hot water storage tank is prohibited.

  In the cogeneration system according to a ninth aspect of the present invention, in any one of the first to eighth aspects, the power generator is a fuel cell, and an exhaust gas path through which the exhaust gas discharged from the fuel cell circulates is provided. In addition, the exhaust gas and the cooling water may exchange heat in the first heat exchanger. According to this configuration, hot water supply and sterilization can be appropriately performed for the fuel cell system while suppressing an increase in cost.

  A cogeneration system according to a tenth aspect of the present invention is a fuel cell system, and in any one of the first to ninth aspects, the upstream of the first heat exchanger and the downstream of the second heat exchanger. A heat dissipator for dissipating the cooling water, and the temperature detector is provided in the recirculation path upstream of the first heat exchanger and downstream of the heat dissipator; When the power generation is being performed, heat is radiated by the radiator so that the temperature detected by the temperature detector is a second predetermined temperature lower than the first predetermined temperature, and the output of the power generation is reduced, The flow rate of the cooling water may be reduced by the circulation pump, and the amount of heat released by the radiator may be reduced so that the temperature detected by the temperature detector becomes the first predetermined temperature.

  According to this configuration, the temperature of the cooling water flowing into the first heat exchanger is lowered by dissipating heat so that the detected temperature becomes the second predetermined temperature. Since the exhaust gas is cooled by the first heat exchanger with the low-temperature cooling water, the moisture in the exhaust gas is condensed. For example, if condensed water is used as reforming water for the reformer, the fuel cell system can be water self-supporting.

  Further, in a state where the output of the power generation and the flow rate of the cooling water are reduced, the heat radiation amount is reduced so that the detected temperature becomes the first predetermined temperature. Thereby, since the temperature fall of the cooling water by heat radiation reduces, the detection temperature of cooling water becomes close to the temperature of hot water storage water. For this reason, the detected temperature of the cooling water can be used to determine the temperature of the hot water storage.

  A cogeneration system according to an eleventh aspect of the present invention is a fuel cell system. In the ninth or tenth aspect, the fuel cell is a modified battery that generates a hydrogen-containing gas using a raw material gas and reformed water. And a stack that performs the power generation using the hydrogen-containing gas and the oxidant gas, branches from the circulation path at a branch point, and circulates the cooling water as the reformed water to the reformer A reforming water path may be further provided. Thus, by using the cooling water as the reforming water, the fuel cell system can be water independent.

  A cogeneration system according to a twelfth aspect of the present invention is a fuel cell system. In the eleventh aspect, the branch point is upstream of the first heat exchanger and downstream of the second heat exchanger. It may be provided in the circulation path. According to this configuration, the cooling water after being cooled and before being heated can be used as the reforming water. For this reason, it is not necessary to use expensive parts having heat resistance, and the increase in cost can be suppressed.

  A cogeneration system according to a thirteenth embodiment of the present invention is a fuel cell system. In the eleventh or twelfth embodiment, the cogeneration system is provided in the circulation path upstream from the branch point and downstream from the second heat exchanger. Further, an ion exchange resin filter for deionizing the cooling water may be further provided. According to this configuration, since the ion-exchanged cooling water is used as the reforming water, it is possible to suppress a decrease in the performance of the reformer due to the ions contained in the cooling water.

  A cogeneration system according to a fourteenth aspect of the present invention is a fuel cell system. In the thirteenth aspect, the cogeneration system is provided in the circulation path upstream from the first heat exchanger and downstream from the second heat exchanger. The second heat exchanger, the radiator, the temperature detector, the ion exchange resin filter, the branch point, and the first heat exchanger are further provided with a radiator that dissipates the cooling water. You may arrange | position in the said circulation path in this order in the flow direction of water.

  According to this configuration, the hot water stored in the second heat exchanger can be efficiently heated by the cooling water in the second heat exchanger by circulating the high-temperature cooling water heated by the first heat exchanger to the second heat exchanger. Also. By circulating the low-temperature cooling water cooled by the second heat exchanger to the radiator, the heat radiation amount in the radiator can be reduced. Furthermore, by detecting the temperature of the cooling water radiated by the radiator with the temperature detector, the radiation can be controlled based on the detected temperature. Furthermore, the heat-resistant deterioration of an ion exchange resin filter can be prevented by distribute | circulating the low temperature cooling water thermally radiated with the heat radiator to the ion exchange resin filter. Furthermore, since the cooling water is circulated to the first heat exchanger via the ion exchange resin filter, generation of scale due to ions in the cooling water can be prevented. Furthermore, the heat-exchange efficiency in a 1st heat exchanger can be improved by distribute | circulating the low temperature cooling water radiated | emitted with the heat radiator to the 1st heat exchanger.

  An operating method of a fuel cell system according to a fifteenth aspect of the present invention includes a fuel cell that generates power, a first heat exchanger that exchanges heat between the exhaust heat from the fuel cell and cooling water, and hot water storage. Circulation in which the cooling water circulates between the stored hot water storage tank, the second heat exchanger that exchanges heat between the cooling water and the hot water, and the first heat exchanger and the second heat exchanger. A cooling pump that circulates the cooling water in the circulation path, and the circulation path that is upstream of the first heat exchanger and downstream of the second heat exchanger, and detects the temperature of the cooling water. A temperature detector, and a time when the power generation is not continuously performed reaches a first predetermined time, or a time when the hot water supply is not continuously performed reaches a second predetermined time. When the hot water supply prohibition mode that does not allow the supply of hot water is set, When power generation is being performed, to reduce the flow rate of the cooling water by the circulation pump, when the temperature detected by the temperature detector reaches a first predetermined temperature to release the hot water supply inhibiting mode.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted.
(First embodiment)

  A cogeneration system 100 according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating an example of a functional configuration of a cogeneration system 100 according to the first embodiment. The cogeneration system 100 includes a power generator 10, a hot water storage tank 11, a circulation path 12, a circulation pump 13, a first heat exchanger 14, a second heat exchanger 15, a temperature detector 16, and a controller 9. .

  The power generator 10 is a device that generates power and generates heat together with electric power. Examples of the generator 10 include a fuel cell, a gas engine, a diesel engine, a gas turbine, and a steam turbine. An exhaust heat path 10a for discharging heat is connected to the generator 10. The exhaust heat path 10 a is connected to an exhaust port (not shown) of the cogeneration system 100 through the first heat exchanger 14. Examples of the exhaust heat include heat of fuel exhaust gas.

  The first heat exchanger 14 is a heat exchanger that exchanges heat between exhaust heat from the generator 10 and cooling water. The first heat exchanger 14 is provided in the exhaust heat path 10a and the circulation path 12, and a known heat exchanger can be used.

  The circulation path 12 is a path through which cooling water circulates between the first heat exchanger 14 and the second heat exchanger 15. For example, in the circulation path 12, the first heat exchanger 14, the circulation pump 13, the second heat exchanger 15, and the temperature detector 16 are arranged in this order (normal order). The cooling water is circulated by the circulation pump 13 so as to pass through these devices in the normal order.

  The circulation pump 13 is a pump that circulates cooling water through the circulation path 12. The circulation pump 13 has, for example, a function (flow rate adjustment function) that can adjust the flow rate of cooling water per unit time flowing through the circulation path 12. The circulation pump 13 adjusts the flow rate of the cooling water that circulates through the circulation path 12 in accordance with a control signal from the controller 9. The flow rate adjusting function may be built in the circulation pump 13 or may be provided separately from the circulation pump 13 as a component having the flow rate adjusting function.

  The hot water storage tank 11 is a tank in which hot water is stored. The hot water storage tank 11 is provided in the circulation path 12 downstream of the circulation pump 13 and upstream of the temperature detector 16, for example, and stores the heat recovered in the first heat exchanger 14 as hot water storage water. The internal space of the hot water storage tank 11 does not communicate with the internal space of the circulation path 12, and the hot water storage tank 11 is provided separately from the circulation path 12. For this reason, the hot water in the hot water storage tank 11 and the cooling water in the circulation path 12 are different from each other and are not mixed.

  The hot water storage tank 11 is connected to a water supply facility (not shown) such as a water supply by a water supply path 11 a. For example, the water supply path 11 a is connected to the lower part of the hot water storage tank 11. Water (tap water) is supplied as hot water storage water from the water supply facility to the hot water storage tank 11 through the water supply path 11a. The hot water storage tank 11 is connected to a hot water supply facility (not shown) by a hot water supply path 11 b, and the hot water supply path 11 b is connected to the upper part of the hot water storage tank 11, for example. The hot water is supplied as hot water from the hot water storage tank 11 to the hot water supply facility via the hot water supply path 11b.

  The second heat exchanger 15 is a heat exchanger that exchanges heat between cooling water and hot water. The second heat exchanger 15 includes a circulation path 12 and a hot water storage tank 11. A portion of the circulation path 12 that constitutes the second heat exchanger 15 by exchanging heat between the cooling water and the hot water is referred to as a cooling water pipe 12a. In FIG. 1, the cooling water pipe 12 a is provided in the hot water storage tank 11 so as to extend in a spiral shape and penetrate the hot water storage tank 11. However, the cooling water pipe 12a and the hot water storage tank 11 should just be provided so that heat exchange with cooling water and hot water storage water is possible. For this reason, the cooling water pipe 12 a may be provided outside the hot water storage tank 11 so as to surround the outer periphery of the hot water storage tank 11.

  The temperature detector 16 is a sensor that is provided in the circulation path 12 upstream of the first heat exchanger 14 and downstream of the second heat exchanger 15 and detects the temperature of the cooling water. For example, since the temperature detector 16 does not exhaust the exhaust heat from the power generator 10 from the cogeneration system 100 at a high temperature, the first heat exchanger 14 can sufficiently cool the exhaust heat so that the cooling water can cool the exhaust heat. It is mainly used for the purpose of detecting the temperature of the cooling water flowing into the heat exchanger 14. The temperature detector 16 outputs the detected temperature (detected temperature) to the controller 9. Examples of the temperature detector 16 include a thermocouple and a thermistor temperature sensor.

  The controller 9 controls each component of the cogeneration system 100. For example, the controller 9 controls the output (discharge amount) of the circulation pump 13 based on the temperature detected by the temperature detector 16. The controller 9 only needs to have a control function, and includes an arithmetic processing unit (not shown) and a storage unit (not shown) for storing a control program. Examples of the arithmetic processing unit include an MPU and a CPU. A memory is exemplified as the storage unit. The controller 9 may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that perform distributed control in cooperation with each other.

  Next, an operation method of the cogeneration system 100 according to the first embodiment will be described using the flowchart of FIG. This operation method is controlled by the controller 9.

  First, the controller 9 determines when the time during which power generation is not continuously performed (power generation stop time) reaches the first predetermined time, or when the hot water supply is not continuously performed (hot water supply suspension time). When the second predetermined time is reached (step S11: YES), a hot water supply prohibiting mode in which supply of hot water is not permitted is set (step S12). The first predetermined time and the second predetermined time are determined by experiments and simulations based on the temperature and volume of the hot water storage tank 11.

  For this reason, the controller 9 measures the elapsed time (power generation stop time) since the previous power generation stopped and the elapsed time (hot water stoppage time) after the previous hot water supply ends. Then, the power generation stop time and the hot water supply stop time are measured until the power generation stop time reaches the first predetermined time or the hot water supply stop time reaches the second predetermined time (step S11: NO).

  When the power generation stop time reaches the first predetermined time (step S11: YES), it is determined that the hot water storage tank 11 needs to be sterilized. That is, if the power generator 10 is generating electric power, the hot water stored in the hot water storage tank 11 is always kept at a high temperature (for example, 70 ° C.) by the exhaust heat of the power generator 10. However, if power generation is not continuously performed for a long time, the temperature of the hot water in the hot water storage tank 11 decreases due to heat dissipation. For example, when the temperature of the hot water stored in the hot water storage tank 11 reaches about 50 ° C., it is said that germs such as Legionella bacteria are likely to propagate. For this reason, if the power generation is not continued for the first predetermined time, it is determined that the hot water storage tank 11 needs to be sterilized.

  Moreover, also when the hot water supply stop time becomes the second predetermined time (step S11: YES), it is determined that the hot water storage tank 11 needs to be sterilized. That is, when hot water is supplied from the hot water storage tank 11, hot water is discharged from the hot water storage tank 11, and clean water is supplied to the hot water storage tank 11 so that the hot water stored in the hot water storage tank 11 is replaced. On the other hand, if the hot water supply is not continuously performed for the second predetermined time, the hot water storage water stays in the hot water storage tank 11 for a long period of time, so that it is determined that the hot water storage tank 11 needs to be sterilized.

  As described above, when it is determined that the hot water stored in the hot water storage tank 11 needs to be sterilized, the controller 9 sets the hot water supply prohibition mode (step S12). Thereby, discharge of the hot water from the hot water storage tank 11 is prohibited, and the hot water is not supplied.

  Subsequently, the controller 9 monitors the power generation of the power generator 10 (step S13). Here, when the power generation is not performed (step S13: NO), the controller 9 maintains the hot water supply prohibition mode (step S12).

  On the other hand, when power generation is being performed (step S13: YES), the controller 9 reduces the flow rate of the cooling water by the circulation pump 13 (step S14). For example, when power generation is started after the power generation stop time reaches the first predetermined time, or when the hot water supply stop time reaches the second predetermined time but power generation is being performed, the controller 9 It is determined that power generation is being performed (step S13: YES). During power generation, the cooling water is heated by the exhaust heat from the power generator 10 in the first heat exchanger 14, and the high-temperature cooling water flows into the second heat exchanger 15. For this reason, the hot water is heated by the high-temperature cooling water in the second heat exchanger 15, the temperature of the hot water storage tank 11 is increased, and the hot water stored in the hot water storage tank 11 is sterilized.

  Here, the controller 9 controls the circulation pump 13 so as to reduce the flow rate of the cooling water flowing through the circulation path 12 (step S14). It is preferable that the amount of heat of the cooling water is set so as to be closer to the amount of heat that can be transferred from the cooling water to the stored hot water per unit time in the second heat exchanger 15. Specifically, the flow rate of the cooling water depends on the amount of exhaust heat of the generator 10, the cross-sectional area of the piping of the circulation path 12, the amount and temperature of hot water stored in the hot water storage tank 11, and the heat exchange efficiency of the second heat exchanger 15. Based on the experiment.

  Thus, as the flow rate of the cooling water flowing through the second heat exchanger 15 decreases, the amount of heat of the cooling water flowing into the second heat exchanger 15 decreases. As the amount of heat of the cooling water flowing into the second heat exchanger 15 decreases, the amount of heat of the cooling water approaches the amount of heat that can be transferred per unit time in the second heat exchanger 15. That is, the heat exchange between the stored hot water and the cooling water in the second heat exchanger 15 is sufficiently performed. Moreover, since the temperature of the cooling water that has flowed out of the second heat exchanger 15 over a longer time can be brought close to the temperature of the hot water, the temperature of the hot water can be determined from the detected temperature of the cooling water. That is, there is no need to provide a temperature detector dedicated to hot water, and it is possible to more accurately detect that the temperature of the hot water has risen to a high enough temperature to sterilize, while suppressing an increase in cost. Can be sterilized appropriately.

  For example, when the cooling water flows from the upper side of the hot water storage tank 11 to the lower side in the second heat exchanger 15, the cooling water is cooled by the hot water storage water. Lower. Therefore, the temperature of the hot water heated by the cooling water is lower at the lower part than at the upper part of the hot water storage tank 11. Then, the cooling water exchanges heat with the low-temperature hot water stored in such a lower portion, and then flows out from the second heat exchanger 15. For this reason, the temperature of the cooling water flowing out from the second heat exchanger 15 becomes substantially equal to the temperature of the hottest hot water in the hot water storage tank 11.

  Thus, the temperature of the cooling water after passing through the second heat exchanger 15 is close to the temperature of the hot water storage. At this time, since the flow rate of the cooling water is reduced, when the temperature detector 16 detects the temperature of the cooling water flowing through the circulation path 12 downstream from the second heat exchanger 15, the detected temperature is the temperature of the hot water storage water. Nearly equal time will be longer. Therefore, the controller 9 acquires the temperature detected by the temperature detector 16 as the temperature of the stored hot water.

  Then, the controller 9 monitors whether or not the temperature detected by the temperature detector 16 has reached the first predetermined temperature (step S15). The first predetermined temperature is a temperature at which the hot water storage tank 11 and the hot water can be sterilized, and is, for example, 60 ° C. or higher and 70 ° C. or lower.

  When the temperature detected by the temperature detector 16 reaches the first predetermined temperature (step S15: YES), the controller 9 cancels the hot water supply prohibition mode (step S16). As described above, when the detected temperature reaches the first predetermined temperature, it can be determined that the entire temperature of the hot water stored in the hot water storage tank 11 is the first predetermined temperature. For this reason, the hot water supply temperature has risen to such a high level that it can be sterilized. Thereby, the sterilized hot water storage can be supplied from the hot water storage tank 11.

  According to the above configuration, the hot water supply prohibition mode is set when the power generation stop time reaches the first predetermined time or when the hot water storage stop time reaches the second predetermined time. Thereby, it is prevented that the hot-water storage water considered to be sterilized is supplied. Moreover, when the temperature detected by the temperature detector 16 reaches the first predetermined temperature, the hot water supply prohibition mode is cancelled. Thereby, since the sterilized hot water storage is supplied, appropriate hot water supply is implement | achieved.

  Furthermore, when power generation is performed, the flow rate of the cooling water is reduced by the circulation pump 13. Thereby, the whole hot water can be heated to such a high temperature that it can be sterilized, and the hot water can be appropriately sterilized. Moreover, the temperature detected by the temperature detector 16 can be acquired as the temperature of the hot water storage. For this reason, the temperature detector 16 that detects the temperature of the cooling water flowing into the first heat exchanger 14 can be used in combination to detect the temperature of the hot water storage, thereby suppressing an increase in cost.

In addition, the cooling water used in the first heat exchanger 14 does not use hot water stored in tap water such as tap water. For this reason, clean water is not supplied to the 1st heat exchanger 14, and it is prevented that a scale generate | occur | produces by heating clean water with the 1st heat exchanger 14. FIG. Therefore, it is possible to suppress an increase in cost without using expensive parts for scaling.
(Second Embodiment)

  An operation method of the cogeneration system 100 according to the second embodiment will be described with reference to the flowchart of FIG. This operation method is controlled by the controller 9. The cogeneration system 100 according to the second embodiment has the configuration shown in FIG.

  In the operation method of FIG. 3, in addition to the processes of steps S11 to S16 of the operation method of FIG. 2, the process of step S17 is further executed between steps S13 and S14. Note that description of steps S11 to S16 is omitted.

  Specifically, when power generation is being performed (step S13: YES), the controller 9 reduces the power generation output (step S17). Thereby, since the amount of exhaust heat of the power generator 10 decreases, the amount of heat given to the cooling water from the exhaust heat from the power generator 10 in the first heat exchanger 14 decreases. Therefore, the heat quantity of the cooling water flowing into the second heat exchanger 15 is reduced, and the heat transfer quantity from the cooling water to the hot water storage water is reduced.

According to the above configuration, in addition to the decrease in the flow rate of the cooling water by the circulation pump 13, the output of the power generation is decreased. Thereby, the amount of heat of the cooling water flowing into the second heat exchanger 15 is reduced, and the amount of heat transfer from the cooling water to the stored hot water is reduced. The temperature change of the cooling water after heat exchange in the first heat exchanger 14 becomes small. For this reason, the temperature change of the hot water and the cooling water after heat exchange in the second heat exchanger 15 can be reduced, and the cooling water is discharged from the second heat exchanger 15 at a temperature substantially equal to the temperature of the hot water for a longer time. Can be made.
(Third embodiment)

  An operation method of the cogeneration system 100 according to the third embodiment will be described with reference to the flowchart of FIG. This operation method is controlled by the controller 9. The cogeneration system 100 according to the third embodiment has the configuration shown in FIG.

  In the operation method of FIG. 4, in addition to the processes of steps S11 to S17 of the operation method of FIG. 3, the process of step S18 is further executed between steps S13 and S17. Note that description of steps S11 to S17 is omitted.

Specifically, when power generation is being performed (step S13: YES), the controller 9 causes power generation at the rated output (step S18). As described above, when the power generator 10 is generated with the rated power, the amount of exhaust heat from the power generator 10 increases. As a result, the amount of heat given to the cooling water from the exhaust heat from the power generator 10 in the first heat exchanger 14 increases, so the amount of cooling water flowing into the second heat exchanger 15 also increases. Therefore, since the amount of heat transfer from the cooling water to the hot water storage in the second heat exchanger 15 increases, the hot water is warmed quickly. Thereby, the period until cancellation of hot water supply prohibition mode can be shortened, and appropriate hot water supply can be performed.
(Fourth embodiment)

  A cogeneration system 100 according to a fourth embodiment will be described with reference to FIG. The cogeneration system 100 of FIG. 5 further includes a radiator 17 in addition to the configuration of the cogeneration system 100 of FIG.

  The radiator 17 is a device that is provided in the circulation path 12 upstream from the first heat exchanger 14 and downstream from the second heat exchanger 15 and radiates cooling water. The radiator 17 is a heat exchanger that exchanges heat between the cooling water flowing through the circulation path 12 and the cooling medium. For example, the radiator 17 may be a radiator whose cooling medium is air. However, the cooling medium is not limited to air, and a gas other than air, a liquid, or the like is used.

  The radiator 17 includes a fan, and the fan can be switched and / or its output can be changed. When the fan is turned on or the fan output is increased to start the fan, heat dissipation by the radiator 17 is started. On the other hand, when the fan is switched off or the fan output is lowered to stop the fan, the heat dissipation by the radiator 17 is stopped. Further, by reducing the output of the fan, the amount of heat released by the radiator 17 is reduced.

  The temperature detector 16 is provided in the circulation path 12 upstream from the first heat exchanger 14 and downstream from the radiator 17. Thereby, the temperature detector 16 detects the temperature of the cooling water flowing into the first heat exchanger 14 and also detects the temperature of the cooling water that has passed through the radiator 17. The temperature detected by the temperature detector 16 can be used for output control of the radiator 17.

  Next, an operation method of the cogeneration system 100 according to the fourth embodiment will be described with reference to the flowchart of FIG. This operation method is controlled by the controller 9. In the driving method of FIG. 6, in addition to the processing of steps S11 to S17 of the driving method of FIG. 3, the processing of step S19 between step S13 and step S17, and step S20 between step S14 and step S15. The above process is further executed. Note that description of steps S11 to S17 is omitted.

  Specifically, when power generation is being performed (step S13: YES), the controller 9 starts heat dissipation by the radiator 17 (step S19). Due to this heat radiation, the cooling water is cooled in the circulation path 12 upstream from the first heat exchanger 14, and the temperature of the cooling water flowing through the first heat exchanger 14 is lowered. Therefore, the heat exchange efficiency in the first heat exchanger 14 can be improved.

At this time, since the cooling water is cooled in the circulation path 12 downstream from the second heat exchanger 15 by heat radiation, the temperature detected by the temperature detector 16 is lower than the temperature of the hot water, and the detected temperature is the temperature of the hot water. It is not easy to use for the determination. For this reason, the controller 9 reduces the power generation output (step S17), reduces the flow rate of the cooling water (step S14), and then reduces the heat dissipation amount by the radiator 17 or stops the heat dissipation (step S14). S20). In this way, a decrease in the temperature of the cooling water is suppressed by a decrease in the amount of heat dissipation or the stoppage of heat dissipation. Therefore, the detected temperature becomes close to the temperature of the hot water, and the detected temperature can be used for determining the temperature of the hot water. Since this detected temperature is substantially equal to or lower than the temperature of the whole hot water, if the detected temperature is the first predetermined temperature, it is determined that the temperature of the whole hot water has reached the first predetermined temperature. can do.
(Fifth embodiment)

  An operation method of the cogeneration system 100 according to the fifth embodiment will be described with reference to the flowchart of FIG. This operation method is controlled by the controller 9. The cogeneration system 100 according to the fifth embodiment has the configuration shown in FIG.

  In the operation method of FIG. 7, in addition to the processes of steps S11 to S16 of the operation method of FIG. 2, the process of step S21 is further executed between steps S15 and S16. Note that description of steps S11 to S16 is omitted.

  Specifically, the controller 9 measures the elapsed time after the temperature detected by the temperature detector 16 reaches the first predetermined temperature (step S15: YES), and this elapsed time becomes the third predetermined time. It is determined whether or not it has been reached (step S21). Here, when the elapsed time reaches the third elapsed time (step S21: YES), the hot water supply prohibition mode is canceled (step S16). The third predetermined time is an arbitrary time greater than zero.

  Accordingly, the state of the hot water stored at the first predetermined temperature or higher is maintained for the third predetermined time. For this reason, the hot water can be continuously heated to a temperature high enough to sterilize the third predetermined time, and the hot water can be sterilized more reliably.

In addition, as a driving | operation method of the cogeneration system 100 which concerns on 5th Embodiment, you may further perform the process of step S21 between step S15 and step S16 of the driving | running method of FIG.3, FIG.4 and FIG.6. Among these, the cogeneration system 100 of the driving | running method of FIG. 6 is equipped with the structure of FIG.
(Sixth embodiment)

  A cogeneration system 100 according to the sixth embodiment will be described with reference to FIGS. 8A, 8B, and 8C. In the cogeneration system 100 according to the sixth embodiment, the second heat exchanger 15 is provided in the hot water storage tank 11, and in the second heat exchanger 15, the cooling water flows from the upper part to the lower part of the hot water storage tank 11. 8A, FIG. 8B, and FIG. 8C are used for the cogeneration system 100 of FIG. 1 and FIG.

  In FIG. 8A, the upstream end of the cooling water pipe 12 a of the circulation path 12 is provided on the upper surface of the hot water storage tank 11, and the downstream end of the cooling water pipe 12 a is provided on the lower surface of the hot water storage tank 11. In FIG. 8B, the upstream end of the cooling water pipe 12 a is provided at the upper part of the first side surface of the hot water storage tank 11, and the downstream end of the cooling water pipe 12 a is provided at the lower part of the first side surface of the hot water storage tank 11. In FIG. 8C, the upstream end of the cooling water pipe 12 a is provided at the upper part of the second side surface of the hot water storage tank 11, and the downstream end of the cooling water pipe 12 a is provided at the lower part of the third side surface facing the second side surface of the hot water storage tank 11. It has been.

  In any of FIGS. 8A to 8C, the cooling water pipe 12 a is disposed in the hot water storage tank 11. In the hot water storage tank 11, the upstream end of the cooling water pipe 12a is disposed above the downstream end. The circulation pump 13 applies pressure to the cooling water so that the cooling water flows to the circulation path 12 upstream of the cooling water pipe 12a, the cooling water pipe 12a, and the circulation path 12 downstream of the cooling water pipe 12a. Thereby, the cooling water flows through the cooling water pipe 12 a from the upper part to the lower part of the hot water storage tank 11 in the second heat exchanger 15. Since the cooling water flows while being cooled by the hot water storage in the second heat exchanger 15, the temperature of the hot water in the upper part of the hot water storage tank 11 is the same as or higher than that of the lower part of the hot water storage tank 11. Therefore, high temperature hot water can be supplied from the upper part of the hot water storage tank 11 via the hot water supply path 11b.

The cooling water exchanges heat with the low-temperature hot water stored in the lower part of the hot water storage tank 11 and then flows out from the second heat exchanger 15. For this reason, the temperature of the cooling water flowing out from the second heat exchanger 15 becomes substantially equal to the temperature of the hottest hot water in the hot water storage tank 11. Therefore, the temperature detected by the temperature detector 16 that detects the temperature of the cooling water can be used to determine the temperature of the hot water.
(Seventh embodiment)

  A cogeneration system 100 according to a seventh embodiment will be described with reference to FIGS. 9A and 9B. The cogeneration system 100 according to the seventh embodiment further includes a hot water supply path 11b, a water supply path 11a, and an on-off valve 18. 9A and 9B is used in the cogeneration system 100 of FIGS. 1, 5, and 8A to 8C.

  The hot water supply path 11b is a path for supplying hot water from the hot water storage tank 11, and connects the hot water storage tank 11 and hot water supply equipment (not shown). The water supply path 11a is a path for supplying clean water to the hot water storage tank 11, and connects the hot water storage tank 11 and a water supply facility (not shown). The water supply path 11 a branches at a branch point 11 a 1 upstream from the hot water storage tank 11. This branch path 11 a 2 is connected to the hot water supply path 11 b at a connection point 11 a 3 downstream from the hot water storage tank 11.

  The on-off valve 18 is a valve that is provided in at least one of the hot water supply path 11b or the water supply path 11a and opens and closes the hot water supply path 11b or the water supply path 11a. 9A is provided in the hot water supply path 11b downstream of the hot water storage tank 11 and upstream of the connection point 11a3, and opens and closes the hot water supply path 11b. 9B is provided in the water supply path 11a upstream from the hot water storage tank 11 and downstream from the branch point 11a1, and opens and closes the water supply path 11a. The on-off valve 18 may be provided in the hot water supply path 11b downstream from the hot water storage tank 11 and downstream from the connection point 11a3, or in the water supply path 11a upstream from the hot water storage tank 11 and upstream from the branch point 11a1.

  In the operation method of the cogeneration system 100 according to the seventh embodiment, the controller 9 does not permit the opening / closing valve 18 to be opened in the process of step S12 in the flowcharts of FIGS. Set hot water prohibition mode.

  For example, when hot water supply is requested by operating a hot water supply facility, the controller 9 permits the opening / closing valve 18 to be opened when the hot water supply prohibition mode is not set. Thereby, the on-off valve 18 opens, and the water supply path 11a and the hot water supply path 11b are released. The clean water is supplied to the hot water storage tank 11 through the water supply passage 11a and heated, and supplied as hot water storage water to the hot water supply facility through the hot water supply passage 11b.

On the other hand, when the hot water supply prohibition mode is set (step S12), the controller 9 does not permit the opening / closing valve 18 to be opened even if hot water supply is requested by operating the hot water supply facility. Thereby, the on-off valve 18 is closed, and the water supply path 11a and / or the hot water supply path 11b are closed. For this reason, the hot water is not supplied from the hot water storage tank 11 to the hot water supply facility, and the hot water supply prohibition mode is realized. However, the clean water flows from the branch point 11a1 of the water supply path 11a through the branch path 11a2, flows into the hot water supply path 11b at the connection point 11a3, and is supplied to the hot water supply facility through the hot water supply path 11b. For this reason, for example, when hot water is heated by a hot water supply facility, it is supplied as hot water, thereby realizing an appropriate hot water supply.
(Eighth embodiment)

  A cogeneration system 100 according to the eighth embodiment will be described with reference to FIG. The cogeneration system 100 according to the eighth embodiment further includes a hot water supply path 11b, a water supply path 11a, and a mixing valve 19. 10 is used in the cogeneration system 100 of FIGS. 1, 5, and 8A to 8C.

  The mixing valve 19 is a valve provided at a connection point 11a3 between the hot water supply path 11b and the water supply path 11a to open and close the hot water supply path 11b and the water supply path 11a. For example, a three-way valve is used as the mixing valve 19. The mixing valve 19 has, for example, two inlets (first inlet and second inlet) and one outlet, and opens and closes the two inlets. The first inlet is connected to the hot water supply path 11b (upstream hot water supply path 11b2) upstream of the mixing valve 19, the second inlet is connected to the branch path 11a2, and the outlet is hot water supply path 11b (downstream) downstream of the mixing valve 19. It is connected to the hot water supply path 11b1).

  In the operation method of the cogeneration system 100 according to the eighth embodiment, the controller 9 opens the upstream hot water supply path 11b2 by the mixing valve 19 in the process of step S12 in the flowcharts of FIGS. 2 to 4, 6, and 7. The hot water supply prohibition mode is set.

  For example, when hot water supply is requested by operating a hot water supply facility, the controller 9 permits the upstream hot water supply path 11b2 to be opened by the mixing valve 19 when the hot water supply prohibition mode is not set. Thus, the mixing valve 19 opens the first inlet and closes the second inlet, the upstream hot water supply path 11b2 is released, and the branch path 11a2 is closed. For this reason, the hot water storage water flows from the hot water storage tank 11 to the downstream hot water supply path 11b1 via the upstream hot water supply path 11b2, and is supplied with hot water in the hot water supply facility.

  Note that the mixing valve 19 may open the first inlet and the second inlet based on the hot water supply temperature, the amount of hot water supply, and the like. In this case, the upstream hot water supply path 11b2 and the branch path 11a2 are released, and the hot water is mixed with the hot water and flows to the downstream hot water supply path 11b1 to be supplied to the hot water supply equipment. Here, the controller 9 can adjust the mixing ratio of the hot water and the hot water supplied to the hot water supply facility and the temperature of the mixed water by changing the opening degree of the first inlet and the second inlet. it can.

On the other hand, when the hot water supply prohibition mode is set (step S12), the controller 9 does not allow the upstream hot water supply path 11b2 to be opened by the mixing valve 19 even if hot water supply is requested by operating the hot water supply facility. Thereby, the mixing valve 19 closes the first inlet and opens the second inlet, the upstream hot water supply path 11b2 is closed, and the branch path 11a2 is released. For this reason, the hot water is not supplied from the hot water storage tank 11 to the hot water supply facility, and the hot water supply prohibition mode is realized. However, the clean water from the branch path 11a2 is supplied to the hot water supply facility through the downstream hot water supply path 11b1. For this reason, for example, when hot water is heated by a hot water supply facility, hot water supply is realized.
(Ninth embodiment)

  A fuel cell system 101 according to a ninth embodiment will be described with reference to FIG. The fuel cell system 101 in FIG. 1 further includes a reformer 21, a reforming water path 23, and an ion exchange resin filter 24 in addition to the configuration of the cogeneration system 100 in FIG. In the fuel cell system 101, the power generator 10 of the cogeneration system 100 is the fuel cell 20, and the exhaust heat path 10 a is the exhaust gas path 22.

  The fuel cell 20 includes a reformer 21 and a stack 20a. The stack 20a generates power using a hydrogen-containing gas and an oxidant gas. Moisture is also generated by this power generation, and the moisture is contained in the exhaust gas and discharged from the stack 20a. An example of the oxidant gas is air. The fuel cell 20 may be, for example, a solid oxide fuel cell and a solid polymer fuel cell.

  The exhaust gas path 22 is a path through which the exhaust gas discharged from the fuel cell 20 flows. The exhaust gas path 22 connects the fuel cell 20 and a discharge port (not shown) of the fuel cell system 101 through the first heat exchanger 14. For example, gas (exhaust gas) discharged from a combustor (not shown) of the fuel cell 20 is discharged outside the fuel cell system 101 through the exhaust gas path 22. The temperature of the exhaust gas flowing through the exhaust gas path 22 is, for example, 200 ° C. when the fuel cell 20 is a solid oxide fuel cell. In the first heat exchanger 14, the exhaust gas and the cooling water exchange heat. Further, the exhaust gas path 22 is branched into a condensed water path 22 a, and the condensed water path 22 a is connected to the circulation path 12 downstream from the first heat exchanger 14.

  The reformer 21 is a reactor that generates a hydrogen-containing gas using raw materials and water (reformed water). In the reformer 21, the raw material undergoes a reforming reaction with water vapor in the presence of a catalyst to generate a hydrogen-containing gas. The reformer 21 is heated to an appropriate temperature of the catalyst, for example, 600 to 700 ° C. Further, the reformer 21 is provided with an evaporator (not shown), and here, steam is generated from the reformed water supplied via the reformed water path 23. The raw material is supplied to the reformer 21 from a raw material supply device (not shown) through a supply path (not shown). The raw material is, for example, a gas containing an organic compound composed of at least carbon and hydrogen, such as city gas mainly composed of methane, natural gas, and LPG. The raw material supplier is a device having a function of adjusting the flow rate of the raw material gas, and examples thereof include a booster and / or a flow rate adjustment valve or a constant displacement pump.

  In the reforming water path 23, the reforming water used in the reaction of the reformer 21 circulates. The reforming water path 23 branches from the circulation path 12 at the branch point 12b. The branch point 12 b is located upstream from the first heat exchanger 14 and downstream from the second heat exchanger 15.

  The ion exchange resin filter 24 is a device that removes (deionizes) ions from the cooling water. The ions to be removed mainly include ions that poison the reformer 21 and the fuel cell 20 catalyst. The ion exchange resin filter 24 is provided on the circulation path 12 upstream from the branch point 12 b and downstream from the second heat exchanger 15. Furthermore, the position of the ion exchange resin filter 24 is preferably closer to the branch point 12b. Preferably, the cooling water may flow through the second heat exchanger 15, the radiator 17, the temperature detector 16, the ion exchange resin filter 24, the branch point 12 b, and the first heat exchanger 14 in this order in the circulation path 12.

  Next, an operation method of the fuel cell system 101 according to the ninth embodiment will be described with reference to the flowchart of FIG. This operation method is controlled by the controller 9. In the driving method of FIG. 12, in addition to the processing of steps S11 to S17 of the driving method of FIG. 3, the processing of step S22 between step S13 and step S17, and step S23 between step S14 and step S15. The above process is further executed. Note that description of steps S11 to S17 is omitted.

  Specifically, when power generation is being performed (step S13: YES), the controller 9 performs heat dissipation by the radiator 17 so that the temperature detected by the temperature detector 16 becomes the second predetermined temperature (step S21). ). The second predetermined temperature is a temperature lower than the first predetermined temperature, and is, for example, the temperature of cooling water that can cool the exhaust gas to the dew point in the first heat exchanger 14. This dew point is a temperature at which the amount of condensed water necessary for water self-sustaining of the fuel cell system 101 can be recovered, and is 40 ° C., for example.

  The controller 9 detects the temperature flowing into the first heat exchanger 14 and increases the output of the fan of the radiator 17 when the detected temperature is higher than the second predetermined temperature. Thereby, the cooling water is radiated by the radiator 17, the cooling water is cooled in the circulation path 12 upstream from the first heat exchanger 14, and the temperature of the cooling water flowing through the first heat exchanger 14 is the second. Decrease to the specified temperature. Thereby, in the first heat exchanger 14, the high-temperature exhaust gas flowing through the exhaust gas path 22 is cooled by the low-temperature cooling water radiated by the radiator 17. When the exhaust gas is cooled to the dew point, the water vapor contained in the exhaust gas is condensed to produce water (condensed water). The condensed water flows into the circulation path 12 through the condensed water path 22a and is used as cooling water.

  Further, the cooling water is cooled by the hot water stored in the second heat exchanger 15 and then cooled by the heat radiation of the radiator 17. Thus, the cooling water which became low temperature flows in into the ion exchange resin filter 24, and ion is removed here. Then, a part of the cooling water is supplied as reforming water to the reformer 21 via the reforming water path 23, and water self-supporting of the fuel cell system 101 is realized. On the other hand, the remaining cooling water flows into the first heat exchanger 14 via the circulation path 12.

  Thus, the water self-supporting of the fuel cell system 101 is maintained by controlling the radiator 17 so that the temperature detected by the temperature detector 16 becomes the second predetermined temperature. However, since the temperature detector 16 detects the temperature of the cooling water cooled by heat radiation, the detected temperature is lower than the temperature of the hot water storage water. Therefore, in order to make the detected temperature close to the temperature of the hot water storage, the controller 9 reduces the output of the power generation and the flow rate of the cooling water (steps S17 and S14), and the detected temperature by the temperature detector 16 is the first predetermined temperature. The amount of heat dissipated by the radiator 17 is reduced so as to reach a temperature (step S23).

  Thereby, since the temperature fall of a cooling water is suppressed by the fall of the thermal radiation amount, the detection temperature of a cooling water becomes close to the temperature of hot water storage water. Thereby, it can use for determination of the temperature of detection temperature and the temperature of hot water storage. Since this detected temperature is lower than the temperature of the entire hot water, if the detected temperature is the first predetermined temperature, it can be determined that the temperature of the entire hot water has reached the first predetermined temperature.

  Note that all the above embodiments may be combined with each other as long as they do not exclude each other. From the above description, many modifications and other embodiments of the present invention are obvious to those skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The cogeneration system of the present invention can be used for a cogeneration system capable of appropriate hot water supply and sterilization while suppressing an increase in cost.

DESCRIPTION OF SYMBOLS 10: Power generator 11: Hot water storage tank 12: Circulation path 13: Circulation pump 14: 1st heat exchanger 15: 2nd heat exchanger 16: Temperature detector 17: Radiator 18: On-off valve 19: Mixing valve 20: Fuel Battery 20a: Stack 21: Reformer 22: Exhaust gas path 23: Reformed water path 24: Ion exchange resin filter 100: Cogeneration system 101: Fuel cell system

Claims (15)

A generator for generating electricity;
A first heat exchanger for exchanging heat between the exhaust heat from the generator and the cooling water;
A hot water storage tank in which hot water is stored;
A second heat exchanger for exchanging heat between the cooling water and the stored hot water;
A circulation path through which the cooling water circulates between the first heat exchanger and the second heat exchanger;
A circulation pump for circulating the cooling water in the circulation path;
A temperature detector that is provided in the circulation path upstream from the first heat exchanger and downstream from the second heat exchanger, and detects the temperature of the cooling water;
A controller, and
The controller is
When the time during which the power generation is not continuously performed reaches a first predetermined time, or when the time during which the hot water is not continuously supplied reaches a second predetermined time, the hot water is supplied. Set the hot water prohibition mode that does not allow
When the power generation is performed, the flow rate of the cooling water is reduced by the circulation pump,
A cogeneration system that cancels the hot water supply prohibition mode when the temperature detected by the temperature detector reaches a first predetermined temperature.   2. The cogeneration system according to claim 1, wherein, when the power generation is performed, the controller reduces the output of the power generation and reduces the flow rate of the cooling water by the circulation pump.   The controller, when the power generation is being performed, causes the power generation to be performed at a rated output, and then reduces the power generation output to decrease the flow rate of the cooling water by the circulation pump. Or the cogeneration system of 2. A heat radiator that is provided in the circulation path upstream from the first heat exchanger and downstream from the second heat exchanger, and dissipates the cooling water;
The temperature detector is provided in the circulation path upstream from the first heat exchanger and downstream from the radiator,
When the power generation is being performed, the controller starts heat dissipation by the radiator, lowers the output of the power generation, decreases the flow rate of the cooling water by the circulation pump, and releases the heat by the radiator. The cogeneration system according to any one of claims 1 to 3, wherein a heat amount is reduced or heat dissipation is stopped.   5. The controller according to claim 1, wherein the controller cancels the hot water supply prohibition mode after an elapsed time after the detected temperature reaches the first predetermined temperature reaches a third predetermined time. 6. The described cogeneration system. The second heat exchanger is provided in the hot water storage tank,
The cogeneration system according to any one of claims 1 to 5, wherein the cooling water flows from an upper part to a lower part of the hot water storage tank in the second heat exchanger. A hot water supply path for supplying the hot water storage from the hot water storage tank;
A water supply path for supplying clean water to the hot water storage tank;
An open / close valve provided on at least one of the hot water supply path or the water supply path, for opening and closing the hot water supply path or the water supply path;
The said controller is a cogeneration system as described in any one of Claims 1-6 which does not permit opening of the said on-off valve, but sets the said hot water supply prohibition mode. A hot water supply path for supplying the hot water storage from the hot water storage tank;
A water supply path connected to the hot water storage tank and the hot water supply path, and supplying clean water to the hot water storage tank;
A mixing valve that is provided at a connection point between the hot water supply path and the water supply path, and opens and closes the hot water supply path and the water supply path;
The cogeneration system according to any one of claims 1 to 6, wherein the controller does not allow the hot water supply path to be opened by the mixing valve and sets the hot water supply prohibition mode. The generator is a fuel cell;
An exhaust gas path through which the exhaust gas discharged from the fuel cell circulates;
The fuel cell system according to any one of claims 1 to 8, wherein the exhaust gas and the cooling water exchange heat in the first heat exchanger. A heat radiator that is provided in the circulation path upstream from the first heat exchanger and downstream from the second heat exchanger, and dissipates the cooling water;
The temperature detector is provided in the circulation path upstream from the first heat exchanger and downstream from the radiator,
When the power generation is performed, the controller performs heat dissipation by the radiator so that a temperature detected by the temperature detector becomes a second predetermined temperature lower than the first predetermined temperature, and outputs the power generation. The flow rate of the cooling water is lowered by the circulation pump, and the heat radiation amount by the radiator is lowered so that the temperature detected by the temperature detector becomes the first predetermined temperature. The fuel cell system according to any one of the above. The fuel cell includes a reformer that generates a hydrogen-containing gas using a raw material gas and reformed water, and a stack that performs the power generation using the hydrogen-containing gas and an oxidant gas,
11. The fuel cell system according to claim 9, further comprising a reforming water path that branches from the circulation path at a branch point and distributes the cooling water as the reforming water to the reformer.   The fuel cell system according to claim 11, wherein the branch point is provided in the circulation path upstream of the first heat exchanger and downstream of the second heat exchanger.   The fuel cell system according to claim 11 or 12, further comprising an ion exchange resin filter provided in the circulation path upstream from the branch point and downstream from the second heat exchanger and deionizing the cooling water. . A heat radiator that is provided in the circulation path upstream from the first heat exchanger and downstream from the second heat exchanger, and dissipates the cooling water;
The second heat exchanger, the radiator, the temperature detector, the ion exchange resin filter, the branch point, and the first heat exchanger are arranged in the circulation path in this order in the flow direction of the cooling water. The fuel cell system according to claim 13. A fuel cell for generating electricity;
A first heat exchanger for exchanging heat between the exhaust heat from the fuel cell and the cooling water;
A hot water storage tank in which hot water is stored;
A second heat exchanger for exchanging heat between the cooling water and the stored hot water;
A circulation path through which the cooling water circulates between the first heat exchanger and the second heat exchanger;
A circulation pump for circulating the cooling water in the circulation path;
A temperature detector that is provided in the circulation path upstream of the first heat exchanger and downstream of the second heat exchanger and detects the temperature of the cooling water;
When the time during which the power generation is not continuously performed reaches a first predetermined time, or when the time during which the hot water is not continuously supplied reaches a second predetermined time, the hot water is supplied. Set the hot water prohibition mode that does not allow
When the power generation is performed, the flow rate of the cooling water is reduced by the circulation pump,
A method of operating a fuel cell system, wherein the hot water supply prohibition mode is canceled when a temperature detected by the temperature detector reaches a first predetermined temperature.

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