JP2008241145A - Cogeneration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cogeneration system capable of improving exhaust heat recovery efficiency. <P>SOLUTION: This cogeneration system 1 stores hot water heated by heat generated when a generator 2 generates electric power, in a hot water storage tank 4, by connecting the generator 2 and the hot water storage tank 4 by an exhaust heat recovery line 5, and has an exhaust heat recovery temperature measuring means 9 measuring the temperature of the hot water recovered to the hot water storage tank 4, a flow rate adjusting means 6 adjusting a flow rate of circulating water circulating in the exhaust heat recovery line 5, and a flow rate control means 30 controlling the flow rate adjusting means 6 so as to adjust the measuring temperature measured by the exhaust heat recovery temperature measuring means 9 to a preset value of the exhaust heat recovery temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cogeneration system in which a generator and a hot water storage tank are connected by an exhaust heat recovery line, and hot water heated by heat generated by the generator during power generation is stored in the hot water storage tank.

  Conventionally, cogeneration systems have been developed for home and business use. The system installs generators such as gas engines and fuel cells in consumers, and the generators supply the primary energy, such as city gas, to cover the customers' power demand and generate electricity. Hot water is stored in hot water storage tanks using the heat generated at the same time as power generation, and the hot water stored covers the demand for hot water and heating for consumers. For this reason, the cogeneration system is excellent in that it reduces primary energy consumption such as commercial power consumption and city gas usage, thereby improving economy and energy saving. In recent years, various proposals have been made to further improve the economic efficiency and energy saving of a cogeneration system.

  For example, the system described in Patent Document 1 connects a generator and a hot water storage tank, and in addition to an exhaust heat recovery line that supplies hot water recovered from exhaust heat generated by the generator to the hot water storage tank, Before supplying the hot water to the hot water storage tank, a recirculation line is provided for returning to the generator and recirculating, and the exhaust heat recovery line and the recirculation line are switched by a three-way valve.

  The system described in Patent Document 1 includes hot water temperature setting means for setting a temperature in a low temperature mode and a temperature in a high temperature mode higher than that. For example, when hot water is stored in a hot water storage tank at a temperature in the low temperature mode. When the demand for hot water supply is greater than the hot water storage capacity, such as when the hot water is filled in the bathtub, hot water is stored by switching the exhaust heat recovery temperature from the low temperature mode temperature to the high temperature mode temperature. At this time, when the exhaust heat recovery temperature is lower than the temperature in the high temperature mode, the hot water recovered by the three-way valve is circulated through the recirculation line, and the hot water is supplied to the hot water storage tank.

  As a result, the amount of heat stored in the hot water storage tank in the system described in Patent Document 1 increases from that in the low temperature mode, and the amount of heat that is insufficient for hot water supply demand decreases compared to that in the low temperature mode. As a result, the primary energy consumption can be reduced and the economy and energy saving can be improved.

JP 2002-22273 A

  However, although the conventional cogeneration system improves economy and energy saving by changing the exhaust heat recovery temperature, the exhaust water is recovered by recirculating the hot water once recovered into the recirculation line. For this reason, the heat dissipation rate was high and the exhaust heat recovery efficiency was poor.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a cogeneration system capable of improving exhaust heat recovery efficiency.

The cogeneration system according to the present invention has the following configuration.
(1) In a cogeneration system in which a generator and a hot water storage tank are connected by an exhaust heat recovery line and hot water heated by heat generated during power generation is stored in the hot water storage tank, the hot water recovered in the hot water storage tank Waste heat recovery temperature measuring means for measuring temperature, flow rate adjusting means for adjusting the flow rate of circulating water to be circulated through the exhaust heat recovery line, and the measured temperature measured by the exhaust heat recovery temperature measurement means are the exhaust heat recovery temperature. Flow rate control means for controlling the flow rate adjustment means so as to adjust to the set value.
The “generator” includes various devices that generate electric power, such as a gas engine and a fuel cell.
The “flow rate adjusting means” includes a pump and a flow rate adjusting valve.

(2) In the invention described in (1), based on the driving performance storage means for storing past driving performance, the driving performance stored in the driving performance storage means and the driving conditions on the prediction target date, Exhaust heat recovery temperature setting means for setting a set value of the exhaust heat recovery temperature of the day.
“Past operation performance” includes various values obtained when operating the cogeneration system in the past, such as water temperature, outside air temperature, heat load, power load, exhaust heat recovery temperature, heat release rate, and generator operating characteristics. including.
In addition, the “operating condition on the prediction target day” includes conditions on the prediction target day that are predicted when the exhaust heat recovery temperature is set, such as the heat storage amount on the prediction target day, the outside air temperature, the water temperature, and the operation state of the generator.

(3) In the invention described in (2), it has a heat release rate storage means for storing the heat release rate generated during exhaust heat recovery in association with the water temperature or the outside air temperature and the exhaust heat recovery temperature, and the exhaust heat recovery temperature setting The means extracts the heat release rate that matches the water temperature, outside air temperature or exhaust heat recovery temperature of the prediction target date from the heat release rate storage means, and sets the exhaust heat recovery temperature of the prediction target date including the extracted heat release rate. Set the value.

(4) In the invention described in (2) or (3), the heat load predicting means for predicting the heat load on the prediction target day, and the heat load predicted by the heat load prediction means are generated on the prediction target date. Exhaust heat recovery temperature correction means for re-predicting the heat load after the time zone in which the deviation is detected and correcting the set value of the exhaust heat recovery temperature when it deviates from the heat load.

(5) In the invention described in (4), the hot water storage temperature measurement means for measuring the upper temperature of the hot water storage tank, and the exhaust heat recovery temperature correction means, the set value of the exhaust heat recovery temperature on the prediction target day, The temperature is corrected to a value equal to or higher than the upper temperature of the hot water tank detected by the hot water temperature measuring means.

(6) The invention according to any one of (1) to (5), further comprising a surplus power heater that is installed on the exhaust heat recovery line and generates heat by surplus power generated by the generator.

(7) In the invention according to (6), the power load / heat load prediction means for predicting the power load and heat load on the prediction target day, and the set value of the exhaust heat recovery temperature on the prediction target day Comparing the amount of heat generated when the generator is operated with the heat load predicted by the power load / heat load prediction means, the hot water time extraction means for extracting a time zone when hot water breaks out, and the hot water shortage The primary energy consumed when the power generation output of the generator is increased before the time zone extracted by the time extraction means, and the generator based on the set value of the exhaust heat recovery temperature on the prediction target day. Compared with the primary energy consumed during operation, if the primary energy is smaller than the latter in the former case, the power generation output of the generator is increased, and surplus power is generated as the power generation output increases. The time zone of the surplus power heater It has a surplus power heater operating time determining means for determining as use time, the.

  The cogeneration system having the above configuration adjusts the flow rate of the circulating water to be circulated through the exhaust heat recovery line, thereby adjusting the temperature of the hot water recovered in the hot water storage tank to the set value of the exhaust heat recovery temperature. Even if the temperature is changed, there is little heat dissipation loss and the heat recovery efficiency can be improved.

  Since the cogeneration system of the present invention sets the set value of the exhaust heat recovery temperature on the prediction target day based on the past operation results and the operation conditions on the prediction target date, the set value of the exhaust heat recovery temperature on the prediction target day Can be optimally set according to the power demand and heat load demand of the customer, the system and external conditions.

  The cogeneration system of the present invention extracts the heat release rate that matches the water temperature or the outside air temperature and the exhaust heat recovery temperature on the prediction target date from the heat release rate storage means, and includes the extracted heat release rate and the exhaust heat recovery temperature on the prediction target date. Therefore, it is possible to set the exhaust heat recovery temperature setting value that is more suitable for the conditions of the prediction target day, taking into consideration the heat radiation loss that varies depending on the installation status of the system and the external environment.

  When the predicted thermal load deviates from the thermal load generated on the prediction target day, the cogeneration system of the present invention re-predicts the thermal load after the time zone in which the deviation is detected, and sets the exhaust heat recovery temperature. Is corrected, the set value of the exhaust heat recovery temperature can be matched with the condition of the prediction target date even when the prediction is not satisfied.

  In the cogeneration system of the present invention, when the set value of the exhaust heat recovery temperature is corrected, the corrected exhaust heat recovery temperature is equal to or higher than the upper temperature of the hot water storage tank. Heat recovery does not cause stratification of the hot water tank and does not reduce the heat storage density of the hot water tank.

  In the cogeneration system of the present invention, the surplus power heater installed on the exhaust heat recovery line generates heat with the surplus power generated by the generator, and the exhaust heat recovery temperature can be adjusted. Can be prevented and energy saving and economic efficiency can be improved.

  In the cogeneration system of the present invention, when there is a time zone in which hot water runs out, the primary energy consumed when the power generation output of the generator is increased in the time zone in which hot water runs out, and exhaust heat recovery on the prediction target day Compared to the primary energy consumed when operating the generator under the set temperature, if the former has a lower primary energy than the latter, the generator output is increased and the generator output is increased. Along with this, the time period in which surplus power is generated is determined as the use time of the surplus power heater, so that the power generation output of the generator is deliberately raised from the power demand to increase the amount of heat recovered by the surplus power heater and prepare for heat demand. It becomes possible. Therefore, the cogeneration system of the present invention can set the exhaust heat recovery temperature to an optimum value by using the heat recovery using the surplus power heater.

  Next, an embodiment of a cogeneration system according to the present invention will be described with reference to the drawings.

<Overall configuration>
FIG. 1 is a schematic configuration diagram of a cogeneration system 1.
The cogeneration system 1 includes a fuel cell 2 that is an example of a “generator” and a hot water storage unit 3.

  The hot water storage unit 3 is configured around a hot water storage tank 4. The hot water storage tank 4 has an exhaust heat recovery line 5 connected to an upper part and a lower part. The exhaust heat recovery line 5 is provided with a pump 6 which is an example of a “flow rate adjusting means”, and the flow rate of circulating water to be circulated through the exhaust heat recovery line 5 is adjusted. The pump 6 serves as a driving force for supplying circulating water in the lower part of the hot water storage tank 4 to the fuel cell 2 and supplying hot water recovered from the heat generated by the fuel cell 2 to the upper part of the hot water storage tank 4. Between the fuel cell 2 and the hot water storage tank 4, a surplus power heater 7 that generates heat by the power generated by the fuel cell 2 is disposed. An outlet temperature sensor 8 is installed between the fuel cell 2 and the surplus power heater 7 to detect the temperature of hot water output from the fuel cell 2.

  In addition, between the surplus electric power heater 7 and the hot water storage tank 4, an exhaust heat temperature sensor that is an example of “exhaust heat recovery temperature measuring means” that measures the temperature of the hot water recovered in the hot water storage tank 4 (exhaust heat recovery temperature). 9 is arranged. Further, the exhaust heat recovery line 5 is provided with an exhaust heat recovery flow rate sensor 10 for detecting the amount of hot water recovered in the hot water storage tank 4 on the upstream side of the pump 6. A hot water storage sensor 11, which is an example of “hot water storage temperature measuring means”, is installed on the side surface of the hot water storage tank 4 to measure the amount of hot water storage and the hot water storage temperature.

  A water line 12 for supplying tap water is connected to the lower part of the hot water storage tank 4. A water thermometer 13 is disposed in the water line 12 and measures the temperature of the tap water.

  The water line 12 is connected to the mixer 14. The mixer 14 is connected via a hot water supply line 15 to a heating device 16 such as a heater, a bath, a wash basin, or a kitchen faucet. The mixer 14 is connected to the upper part of the hot water storage tank 4 through the hot water supply line 24, and supplies the hot water supply water adjusted to an appropriate temperature by mixing the hot water stored in the hot water storage tank 4 and the tap water in the water supply line 12. To do. The hot water supply line 15 is provided with a heat source device 17 such as a hot water heater for cooking hot water using gas or electricity as an energy source. The heat source device 17 includes a flow meter 18 that measures the amount of hot water supplied to the thermal device 16 (in other words, the amount of hot water consumed by the thermal device 16 (heat load)).

  On the other hand, the fuel cell 2 is supplied with city gas and generates power. The fuel cell 2 includes a power supply control device 19 and a power meter 22. The power supply control device 19 is connected to a commercial power source 20, and the generated power generated by the fuel cell 2 or the commercial power supplied to the commercial power source 20 is supplied to a power device 21 such as a home appliance via a power meter 22. Supply. At this time, the power meter 22 measures the amount of power supplied to the power device 21 (in other words, the amount of power consumed by the power device 21 (power load)).

  The operation of the cogeneration system 1 is controlled by the controller 30. The controller 30 is connected to an outside air temperature sensor 23 that is attached to a covering case (not shown) of the cogeneration system 1 and measures the outside air temperature.

<Electric block configuration of controller>
FIG. 2 is a diagram showing an electrical block configuration of the controller 30 shown in FIG.
The controller 30 includes a CPU 31, a ROM 32, a RAM 33, a hard disk drive (hereinafter referred to as “HDD”) 34, a fuel cell 2, a pump 6, a surplus power heater 7, a mixer 14, and a heat source. Machine 17, power supply control device 19, outlet temperature sensor 8, exhaust heat temperature sensor 9, exhaust heat recovery flow sensor 10, hot water storage sensor 11, water temperature meter 13, flow meter 18, and electric energy meter 22, An outside air temperature sensor 23 is connected via a bus 35.

The CPU 31 processes and calculates data and controls the operation of the cogeneration system 1.
The ROM 32 is a read-only nonvolatile memory and stores various data and programs.
The RAM 33 is a readable / writable volatile memory, and stores various data and programs.

  The HDD 34 is a readable / writable nonvolatile memory and stores various data and programs. In the present embodiment, the operation plan program 41 and the operation control program 42 are stored in the HDD 34. Also, the HDD 34 has a heat dissipation rate storage means 43, a water temperature storage means 44, an outside air temperature storage means 45, a power load / deviation storage means 46, a heat load / deviation storage means 47, an exhaust heat recovery temperature storage means 48, and an exhaust heat recovery. Each storage area of the amount storage means 49 and the power load prediction method storage means 50 is provided.

  The operation plan program 41 is based on past operation results such as water temperature, outside air temperature, past power load, past heat load, past amount of exhaust heat recovery, etc. Sets the temperature setting value. In addition, the operation planning program 41 increases the power generation output of the fuel cell 2 in consideration of the primary energy consumed under the set value of the exhaust heat recovery temperature on the prediction target day, and surplus as the power generation output increases. The time zone in which power is generated is determined as the usage time of the surplus power heater 7. Specific processing of the operation plan program 41 is as shown in FIGS. 3 to 6 and will be described later.

  The operation control program 42 operates the cogeneration system 1 while monitoring the exhaust heat recovery temperature and performing feedback control on the prediction target day. Specifically, the operation control program 42 controls the pump 6 so as to adjust the measured temperature measured by the exhaust heat recovery temperature sensor 9 to the set value of the exhaust heat recovery temperature on the prediction target day. When the predicted heat load deviates from the heat load on the prediction target day, the heat load after the time zone in which the deviation is detected is re-predicted, and the set value of the exhaust heat recovery temperature on the prediction target day is corrected. Is. Specific processing of the operation control program 42 is as shown in FIG. 8 and will be described later.

  The heat release rate storage means 43 is a database that periodically calculates the heat release rate generated during exhaust heat recovery and stores it in association with the water temperature or outside air temperature and the exhaust heat recovery temperature. Since the water temperature reflects the outside air temperature, it can be a standard for grasping the external conditions of the cogeneration system 1 instead of the outside air temperature. When the temperature difference between the exhaust heat recovery temperature and the outside air temperature (water temperature) is large, it is easy to radiate heat from the piping of the exhaust heat recovery line 5, and when the temperature difference between the exhaust heat recovery temperature and the outside air temperature (water temperature) is small Since it is difficult to radiate heat from the piping of the exhaust heat recovery line 5, it is appropriate to manage the heat dissipation rate in association with the water temperature or the outside air temperature and the exhaust heat recovery temperature.

  The heat release rate is obtained by subtracting the outlet temperature of the fuel cell 2 detected by the outlet temperature sensor 8 from the upper temperature of the hot water storage tank 4 detected by the hot water storage sensor 11, and the exhaust heat recovery flow rate measured by the exhaust heat recovery flow rate sensor 10. (Heat dissipation rate = (upper temperature of hot water storage tank 4−outlet temperature of fuel cell 2) × exhaust heat recovery flow rate). The calculated heat release rate is stored in association with the outside air temperature and the exhaust heat recovery temperature, for example, as shown in FIG. Since the heat release rate changes with changes in the power generation output and exhaust heat recovery flow rate even if the exhaust heat recovery temperature is constant, for example, in the format shown in FIG. It is stored in the heat dissipation rate storage means 43.

  As shown in Fig. 7, the heat release rate is not only organized by the outside air temperature and exhaust heat recovery temperature, but also the heat release rate is arranged in association with the power generation output and exhaust heat recovery flow rate to improve the heat release rate calculation accuracy. Also good.

The water temperature storage means 44 is a database that stores the water temperature measured by the water thermometer 13 in association with the date and time as integrated (average) data at predetermined intervals.
The outside air temperature storage means 45 is a database that stores the outside air temperature measured by the outside air temperature sensor 23 in association with the date and time as integrated (average) data at a predetermined interval.
The power load / deviation storage means 46 is a database that stores the power load measured by the power meter 22 and its deviation as integrated (average) data at predetermined intervals in association with the date and time.
The thermal load / deviation storage means 47 is a database that stores the thermal load measured by the flow meter 18 and its deviation as integrated (average) data at predetermined intervals in association with the date and time.

The exhaust heat recovery temperature storage means 48 is a database that stores the exhaust heat recovery temperature detected by the exhaust heat temperature sensor 9 in association with the date and time.
The exhaust heat recovery amount storage means 49 is a database that stores the flow rate measured by the exhaust heat recovery flow rate sensor 10 in association with the date and time as integrated (average) data at a predetermined interval.

  In this embodiment, the heat release rate storage means 43, the water temperature storage means 44, the outside air temperature storage means 45, the power load / deviation storage means 46, the thermal load / deviation storage means 47, the exhaust heat recovery temperature storage means 48, the exhaust heat recovery amount. The storage means 49 constitutes an example of “driving result storage means”.

  The power load prediction method storage unit 50 is a database that stores the power load prediction method used when predicting the power load on the prediction target day in association with the date and time. The power load prediction method is selected from any one of the weighted average of the same day, the weighted average of one week, and the data of the previous day. The power load prediction method is selected from the above options because the power load does not vary greatly from day to day due to the influence of the outside air temperature and water temperature, even when the season changes, for example, compared to the heat load.

<Description of operation: Operation plan>
Next, the operation of the cogeneration system 1 having the above configuration will be described. First, a case where an operation plan for a prediction target day is created will be described.
The operation plan for the prediction target day is performed, for example, by the CPU 31 reading and executing the operation plan program 41 on the day before the prediction target date.

FIG. 3 is a flowchart of the operation planning program 41 shown in FIG. FIG. 4 is a flowchart following the operation plan program 41 shown in FIG.
The CPU 31 executes the thermal load prediction logic in step 1 of FIG. 3 (hereinafter abbreviated as “S1”). FIG. 5 is a sub-flowchart of the thermal load prediction logic (S1) shown in FIG. In the heat load prediction logic, for example, the hot water temperature is low and the amount of hot water used is low in summer, and the hot load is high and the amount of hot water used is high in winter. In consideration of the outside air temperature and the influence of the water temperature that fluctuates with the outside air temperature, the heat load on the prediction target day is predicted for each time zone.

  Specifically, in S101 of FIG. 5, the thermal load data and water temperature data (for the past 4 to 12 weeks) on the same day as the prediction target date are read from the thermal load / deviation storage means 47 and the water temperature storage means 43. In S102, urgent water temperature data (for the past three days to one week) is read from the water temperature storage means 43 on the prediction target day. In S103, a correlation equation (heat load = a × water temperature + b) for the time period is calculated from the heat load data and the water temperature data read in S101 using the least square method.

  Then, in S104, it is determined whether or not the determination coefficient for the time period is greater than or equal to a predetermined value. When the determination coefficient of the time zone is not equal to or greater than the predetermined value (S104: NO), the heat load data and the water temperature data on the same day of the past 4 to 12 weeks are predicted to be the same. The heat load data and the water temperature data read in step 1 are averaged to obtain the heat load data and the water temperature data for the time zone of the prediction target date. Then, it progresses to S107.

  On the other hand, when the determination coefficient for the time period is equal to or greater than the predetermined value (S104: YES), the heat load data and the water temperature data on the same day of the past 4 to 12 weeks are not in the same tendency. Therefore, even if this is averaged, the heat load and water temperature on the prediction target day cannot be accurately predicted. Therefore, in S105, the average water temperature data acquired in S102 is used as the water temperature for the prediction target day. In S106, the heat load for the time zone of the prediction target day is calculated from the correlation equation calculated in S103 and the water temperature of the prediction target day averaged in S105. Then, it progresses to S107.

  In S107, it is determined whether the correlation equation has been calculated up to the final time of the prediction target date. If the correlation formula has not been calculated until the final time of the prediction target date (S107: NO), it means that the heat load is not predicted for all the time zones of the prediction target date, so the process returns to S103, and the prediction target Predict the heat load for the next time of day. On the other hand, when the correlation equation is calculated up to the final time of the prediction target date (S107: YES), it means that the thermal load is predicted for all the time zones of the prediction target date, and the process returns to S1 in FIG.

  In the description of the heat load logic, the heat load on the prediction target day is predicted based on the water temperature data and the heat load data. However, the outside air temperature data in the outside air temperature storage means 45 is used instead of the water temperature data, and the prediction object is used. The daily heat load may be predicted. Thus, since S1 predicts the heat load on the prediction target day, it can be an example of “thermal load predicting means”.

  Thereafter, in S2 of FIG. 3, the power generation output calculation logic is executed. FIG. 6 is a sub-flowchart of the power generation output calculation logic (S2) shown in FIG. Based on the past power load, the power generation output calculation logic predicts the power load and power generation output on the prediction target day by time period.

  Specifically, in S201 of FIG. 6, the latest one-week power load prediction method is read from the power load prediction method storage unit 50. In S202, the most numerous prediction methods read in the latest one week are set as the next day power load prediction method. In S203, based on the prediction method determined in S202, the power load and power load deviation on the prediction target day are read from the power load / deviation storage means 46, and the power load on the prediction target day is predicted. In S204, the power generation output of the fuel cell 2 is calculated from the calculated power load and power load deviation, that is, the power load predicted on the prediction target date. Thereafter, the process returns to S2 of FIG.

  Therefore, the heat load and power load on the prediction target day are predicted by the processes of S1 and S2 in FIG. Therefore, the processing of S1 and S2 can be an example of “electric power load / thermal load prediction means”.

  Then, in S3 to S12 of FIG. 3, a set value of the exhaust heat recovery temperature on the prediction target day that is most energy saving is set based on the heat load, power load, and power generation output calculated in S1 and S2. In this sense, the processing of S3 to S12 can be an example of “exhaust heat recovery temperature setting means”.

  Specifically, in S3, it is assumed that X is 50 ° C. and Y is 0:00. In S4, the exhaust heat recovery temperature is set to X ° C. And the full heat storage amount of the hot water storage tank 4 when exhaust heat recovery temperature is X degreeC is calculated. Here, the full heat storage amount of the hot water storage tank 4 when the exhaust heat recovery temperature is 50 ° C. is calculated. Thereby, the maximum heat storage density of the hot water storage tank 4 under the exhaust heat recovery temperature X ° C. (here, 50 ° C.) is grasped.

  In S5, the operation method of the fuel cell 2 is a continuous load following operation, and the amount of power received from the commercial power source 20 at Y is calculated by subtracting the generated power output at Y from the power load at Y calculated in S2. To do. Further, the amount of city gas consumed by the fuel cell 2 during operation (fuel cell gas consumption) is calculated. Further, the amount of city gas consumed (hot water consumption) is calculated by subtracting the amount of heat stored in the hot water storage tank 4 from the heat load calculated in S1 and operating the heat source unit 17 to heat the water when the hot water runs out. calculate. Further, the exhaust heat recovery heat amount recovered in the hot water storage tank 4 when the fuel cell 2 is operated at the time of Y is calculated. When the hot water storage tank is fully charged, the exhaust heat recovery amount is set to zero. Further, a graph that matches the conditions of the prediction target day is extracted from the graph stored in the heat dissipation rate storage means 43, the outside air temperature on the prediction target day is applied to the outside temperature on the horizontal axis of the graph, and the exhaust heat recovery on the vertical axis is performed. The exhaust heat recovery temperature X ° C. is applied to the temperature, and the heat dissipation rate at which they intersect is calculated.

  In S6, the primary energy is calculated. The primary energy is calculated by adding the received power amount calculated in S5, the fuel cell gas consumption amount, and the hot water gas consumption amount. Thereby, the primary energy consumed in the time zone of Y is calculated. When the heat dissipation rate is high, the fuel cell gas consumption and the hot water gas consumption tend to increase. When the heat dissipation rate is low, the fuel cell gas consumption and the hot water gas consumption tend to decrease. Therefore, the calculated primary energy reflects the heat dissipation rate calculated in S5.

  In S7, it is determined whether or not the primary energy has been calculated up to the final time of the prediction target date. If the primary energy has not been calculated until the final time of the prediction target day (S7: NO), 1 is added to Y to advance the time of the prediction target day by 1 hour in S8, and the process returns to S5. Then, in the processes after S5, the primary energy of the next time is calculated in the same manner as described above.

  When the processes of S5 to S8 are repeated and the primary energy is calculated until the final time of the prediction target day (S7: YES), the primary energy of each time zone calculated by repeating the processes of S5 to S8 is calculated in S9. Addition and the primary energy for one day of the prediction target date are calculated.

  In S10, it is determined whether or not the exhaust heat recovery temperature X is 85 ° C. The determination reference value “85 ° C.” is the maximum exhaust heat recovery temperature that can be recovered from the fuel cell 2. Accordingly, the determination reference value can be changed depending on the type of generator. At this time, the exhaust heat recovery temperature X is 50 ° C., which is lower than the determination reference value of 85 ° C. (S10: NO). In S11, 1 is added to X, and the exhaust heat recovery temperature X is set to 1 ° C. increase. Here, the exhaust heat recovery temperature is set to 51 ° C. Also, the time Y of the prediction target date is set to 0:00. Thereafter, the process returns to S4. Then, by performing the processes of S4 to S9, the primary energy for one day of the prediction target day when the exhaust heat recovery temperature is 51 ° C. is calculated.

  Thus, if the process of S4-S11 is repeated and the primary energy for 1 day of prediction object days is calculated for every exhaust heat recovery temperature of 50-85 degreeC, in S12, the primary energy for 1 day of prediction object days will be obtained. The lowest exhaust heat recovery temperature X is set to the set value of the exhaust heat recovery temperature on the prediction target day. As described above, the primary energy of each time zone reflects the heat dissipation rate stored in the heat dissipation rate storage means 43, and the heat dissipation rate is also included in the primary energy for one day of the prediction target day, which is the sum of these. Is naturally reflected. Therefore, the set value of the exhaust heat temperature on the prediction target day is set based on the amount of heat radiation loss in each condition of the heat recovery temperature and the outside air temperature, and the heat recovery efficiency becomes the highest.

  Then, in the processing of S13 to S23 of FIG. 4, the time zone in which the surplus power heater 7 is used is determined based on the exhaust heat recovery temperature X set above.

  Specifically, in S13, the primary energy for one day of the prediction target date calculated based on the set value of the exhaust heat recovery temperature set in S12 of FIG. 3 is set as the conventional value. In S14, when the fuel cell 2 is continuously operated following the set value of the exhaust heat recovery temperature on the prediction target day, the amount of heat stored in the hot water storage tank 4 and the heat load predicted in S1 of FIG. And check the time zone when the hot water runs out. The time zone when the hot water runs out is set to Z o'clock. In this sense, the process of S14 can be an example of “hot water extraction time”.

  In S15, the power generation output one hour before the time zone Z when the hot water runs out is increased. This is because heat is stored in the hot water storage tank 4 before the hot water runs out. However, the value of the power generation output is a value at which the overall efficiency is greater than 38%. The reason why 38% is set as the judgment reference value is the power generation efficiency of the thermal power average, and by making the value exceeding 38%, the economic efficiency and energy saving performance of the cogeneration system 1 can be utilized.

  In S16, the primary energy when the power generation output is increased is calculated, and the primary energy for one day on the prediction target day is recalculated. The recalculated value is referred to as “currently calculated value”. In S17, it is determined whether or not the conventional value is larger than the current calculated value. That is, it is determined which primary energy is small, economical and energy saving.

  When the conventional value is larger than the current calculated value (S17: YES), the current calculated value has higher economy and energy saving than the conventional value, so in S18 the power generation output is increased as in S16. Then, it progresses to S20. On the other hand, if the conventional value is less than or equal to the current calculated value (S17: NO), the conventional value has the same level of economic efficiency and energy saving as the current calculated value or higher, so the power generation output is not increased in S19. . Then, it progresses to S20.

  In S20, 1 is subtracted from Z, and the time zone for confirming the change of the power generation output due to the hot water shortage is advanced by 1 hour. Then, in S21, it is determined whether or not the earlier time zone is 0 and the start time of the prediction target day. When it is not the start time of the prediction target day (S21: NO), the process returns to S15. And in the process of S15-S20, the electric power generation output 2 hours before the time slot | zone used as hot water specified in S14 is increased, and it is judged whether an electric power generation output is made to increase from a conventional value.

  In this way, when the processes of S15 to S21 are repeated and the power generation output is increased appropriately so as not to increase the primary energy within the range of the conventional value, going back to the start time of the prediction target day from the time zone Z when the hot water runs out ( (S21: YES), in S22, the power generation output and the power load are compared to check the time zone in which surplus power is generated. The time zone in which the surplus power is generated is set as the time zone in which the surplus power heater 7 is used.

  Therefore, by executing the processing of S15 to S22, the primary energy consumed when the power generation output is increased before the time when the hot water runs out and the set value of the exhaust heat recovery temperature on the prediction target day are obtained. Compared with the primary energy consumed when operating the fuel cell 2 in the case where the primary energy is smaller in the former case than in the latter case, the power generation output of the fuel cell 2 is increased, and the generated power increases. Thus, a time zone in which surplus power is generated is determined as a usage time of the surplus power heater 7. In this sense, the processing of S15 to S22 can be an example of “surplus power heater usage time determining means”.

  And in S23, the heat storage amount which increases by use of the surplus electric power heater 7 is calculated. In S24, the heat storage amount of the hot water storage tank 4 is recalculated including the increased heat storage amount calculated in S23, and the heat storage amount of the hot water storage tank 4 and the heat load calculated in S1 are compared, resulting in another hot water outage. Check the time zone. Then, in S25, it is determined whether there is another time zone in which hot water runs out. If there is another time zone when the hot water runs out (S25: YES), the process returns to S14 and repeats the processing of S14 to S24 to identify the time zone where the power generation output is increased retroactively from the time zone when the hot water runs out Then, the surplus power heater 7 is used in a time zone where surplus power is generated. On the other hand, when there is no other time zone when the hot water runs out (S25: NO), the process is terminated.

<Operation control>
Next, a case where the operation of the cogeneration system 1 is controlled on the prediction target day will be described. The operation control is performed by the CPU 31 reading and executing the operation control program 42 from the HDD 34. FIG. 8 is a flowchart of the operation control program 42 shown in FIG. The CPU 31 adjusts the flow rate of the circulating water to be circulated through the exhaust heat recovery line 5 so as to adjust the exhaust heat recovery temperature to the set value of the exhaust heat recovery temperature of the prediction target day, while adjusting the heat load and power load of the prediction target day. , Monitoring whether the prediction of water temperature, etc. deviates from the actual value on the day of forecast, and if the prediction of heat load, power load, water temperature, etc. of the day of prediction deviates from the actual value on the day of prediction The exhaust heat recovery temperature is corrected to perform optimum operation.

  Specifically, in S31 of FIG. 8, it is determined whether it is the start time of the prediction target day. When it is not the start time of the prediction target day (S31: NO), it waits until the start time of the prediction target day. When it is the start time of the prediction target day (S31: YES), in S32, the control time T is set to 0, and the operation control time of the prediction target day is reset. In S33, the operation control of the cogeneration system 1 is started according to the operation plan on the prediction target day. That is, the operation of the fuel cell 2 and the pump 6 is started.

  In S34, the exhaust heat temperature sensor 9 measures the exhaust heat recovery temperature. In S35, it is determined whether the exhaust heat recovery temperature (measured exhaust heat recovery temperature) measured by the exhaust heat temperature sensor 9 is higher than the set value of the exhaust heat recovery temperature on the prediction target day. When the measured exhaust heat recovery temperature is not higher than the set value (S35: NO), the process proceeds to S37. On the other hand, when the measured exhaust heat recovery temperature is higher than the set value (S35: YES), the operation of the pump 6 is changed so that the flow rate of the pump 6 sent to the exhaust heat recovery line 5 is increased in S36. This is because the Reynolds number is decreased by increasing the flow rate, the exhaust heat recovery rate is lowered, and the exhaust heat recovery temperature can be lowered. Thereafter, the process proceeds to S37.

  In S37, it is determined whether or not the measured exhaust heat recovery temperature is lower than a set value. If the measured exhaust heat recovery temperature is not lower than the set value (S37: NO), the process proceeds to S39. On the other hand, when the measured exhaust heat recovery temperature is lower than the set value (S37: YES), the operation of the pump 6 is changed so that the flow rate of the pump 6 sent to the exhaust heat recovery line 5 is decreased in S38. This is because the Reynolds number is increased by reducing the flow rate, the exhaust heat recovery rate is improved, and the exhaust heat recovery temperature can be raised. Thereafter, the process proceeds to S39.

  Therefore, the flow rate of the circulating water sent from the pump 6 to the exhaust heat recovery line 5 is adjusted by the processes of S35 to S38, and the hot water supplied to the hot water storage tank 4 is adjusted to the exhaust heat recovery temperature. Therefore, the processing of S35 to S38 can be an example of “flow rate adjusting means”.

  Then, in S39, it is determined whether or not the predicted power load and heat load are deviated from the actual power load and actual heat load that are actually consumed on the day of prediction target. If the predicted power load and heat load are not deviated from the actual power load and actual heat load (S39: NO), the process proceeds to S43.

  If the predicted power load and thermal load deviate from the actual power load and actual heat load (S39: YES), the thermal load pattern after time T during operation control is corrected in S40. In S41, the actual heat storage amount actually stored in the hot water storage tank 4 is examined based on the measurement result of the hot water storage sensor 11. Then, the set value of the exhaust heat recovery temperature is corrected so as to cover the heat load pattern corrected in S40 by the actual heat storage amount of the hot water storage tank 4 and the exhaust heat recovery amount recovered in the hot water storage tank 4. In this sense, the processing of S39 to S41 can be an example of “exhaust heat recovery temperature correction means”.

  In S42, the temperature of the upper part of the hot water storage tank 4 is measured by the hot water storage sensor 11, and it is determined whether or not the corrected exhaust heat recovery temperature is lower than the upper temperature of the hot water storage tank 4. This is because if the corrected exhaust heat recovery temperature is lower than the upper temperature of the hot water storage tank 4, the stratified collapse of the hot water storage tank 4 occurs when exhaust heat recovery is performed according to the corrected exhaust heat recovery temperature. If the corrected exhaust heat recovery temperature is lower than the upper temperature of the hot water storage tank 4 (S42: YES), the process returns to S41, the exhaust heat recovery temperature is reset, and it is corrected again. On the other hand, if the corrected exhaust heat recovery temperature is not lower than the upper temperature of the hot water storage tank 4 (S42: NO), the process proceeds to S43.

  In S43, 1 is added to T, and the control time T is advanced by 1 hour. In S44, it is determined whether or not the control target time is the final time of the prediction target date. If the control time T is not the final time of the prediction target date (S44: NO), it is determined in S45 whether or not the control time T has elapsed. If the control time T has not elapsed (S45: NO), the process waits as it is.

  When the control time T has elapsed (S45: YES), the process returns to S34. And the process of S34-S44 is repeated, the flow rate of the circulating water which the pump 6 sends to the exhaust heat recovery line 5 is adjusted so that the exhaust heat temperature sensor 9 measures the exhaust heat recovery temperature on the prediction target day, and the exhaust heat. Feedback control of recovery temperature. Further, when the power load and the heat load deviate from the actual power load and the heat load, the exhaust heat recovery temperature is corrected.

  When the final time of the prediction target day is reached (S44: YES), in S46, the operation control of the prediction target day is ended and the process is ended.

<Effect>
Therefore, the cogeneration system 1 of this embodiment adjusts the flow rate of the circulating water circulated through the exhaust heat recovery line 5 to adjust the temperature of hot water recovered in the hot water storage tank 4 to the set value of the exhaust heat recovery temperature. Therefore (see S34 to S38 in FIG. 8), even if the exhaust heat recovery temperature is changed, there is little heat dissipation loss, and the heat recovery efficiency can be improved.

  The cogeneration system 1 of the present embodiment sets the set value of the exhaust heat recovery temperature on the prediction target day based on the past operation results and the operation conditions on the prediction target day (see S1 to S12 in FIG. 3). The set value of the exhaust heat recovery temperature on the prediction target day can be optimally set according to the electric power demand of the customer, the heat load demand, the system and external conditions.

  The cogeneration system 1 of the present embodiment extracts a heat release rate that matches the water temperature or outside air temperature of the prediction target date and the exhaust heat recovery temperature from the heat release rate storage means 43, and includes the extracted heat release rate and the exhaustion rate of the prediction target date. Since the set value of the heat recovery temperature is set (see S12 in FIG. 3), the set value of the exhaust heat recovery temperature that is more suitable for the conditions of the prediction target day is set based on the heat dissipation loss that varies depending on the installation status of the system and the external environment. be able to.

  When the predicted heat load deviates from the heat load generated on the day of the prediction target, the cogeneration system 1 of the present embodiment re-predicts the heat load after the time zone in which the deviation is detected, and calculates the exhaust heat recovery temperature. Since the set value is corrected (see S39 in FIG. 8: YES, S40, S41), even if the set value of the exhaust heat recovery temperature is unpredictable and does not meet the conditions on the prediction target day, the exhaust heat recovery temperature is set. The value can be matched to the conditions for the forecast date.

  In the cogeneration system 1 of the present embodiment, when the set value of the exhaust heat recovery temperature is corrected, the corrected exhaust heat recovery temperature is equal to or higher than the upper temperature of the hot water storage tank (see S42 in FIG. 8: NO). Then, exhaust heat is recovered at a temperature lower than the upper temperature of the hot water storage tank 4 to cause stratification collapse of the hot water storage tank 4, and the heat storage density of the hot water storage tank 4 is not reduced.

  In the cogeneration system 1 of the present embodiment, the surplus power heater 7 installed on the exhaust heat recovery line 5 generates heat by surplus power generated by the fuel cell 2 and can adjust the exhaust heat recovery temperature ( 1), it is possible to prevent surplus power from being generated and flow to the commercial power source 20 side (so-called surplus power oozing), and to improve energy saving and economy.

  The cogeneration system 1 according to the present embodiment includes the primary energy consumed when the power generation output of the fuel cell 2 is increased in the time zone in which hot water runs out, and the prediction target date. Compared with the primary energy consumed when the fuel cell 2 is operated under the set value of the exhaust heat recovery temperature, if the former has a smaller primary energy than the latter, the power generation output of the fuel cell 2 is increased, Since the time period in which surplus power is generated as the power generation output increases is determined as the usage time of the surplus power heater 7, the power output of the fuel cell 2 is intentionally lifted from the power demand to increase the amount of heat recovered by the surplus power heater 7. It becomes possible to prepare for heat demand. Therefore, the cogeneration system 1 of the present embodiment can set the exhaust heat recovery temperature to an optimum value by using heat recovery using the surplus power heater 7 together.

<Example>
For example, when operating the cogeneration system 1 in the summer, the heat load is reduced by reducing the flow rate under the conditions that the power load is 20 kW, the heat load is 20 MJ, the power generation amount of the fuel cell is constant at 600 W, and the power generation efficiency is 35%. A comparison is made between when the recovery temperature is set to 80 ° C. and when the exhaust heat recovery temperature is set to 60 ° C. by increasing the flow rate. When the exhaust heat recovery temperature is set to 80 ° C., the exhaust heat efficiency is 30%, whereas when the exhaust heat recovery temperature is set to 60 ° C., the exhaust heat efficiency is 40%.

  Under this condition, when the exhaust heat recovery temperature is 80 ° C., the energy saving rate is 11.4%, whereas when the exhaust heat recovery temperature is 60 ° C., the energy saving rate is 9.0%. The energy saving rate increases by 2.4% when the exhaust heat recovery temperature is set to 80 ° C. Therefore, in the summer, by changing the exhaust heat recovery temperature from 60 ° C. to 80 ° C., it is possible to improve economy and energy saving.

The following can be considered for this reason.
When the exhaust heat recovery temperature is set high, reducing the flow rate improves the heat recovery rate. The outside air temperature surrounding the exhaust heat recovery line 5 is high in summer, and even if the exhaust heat recovery temperature is high, heat loss is less likely to occur while hot water flows from the fuel cell 2 to the hot water storage tank 4. In summer, the heat load is less than 20 MJ, and the water supply temperature is lower than in winter. If hot water is stored in the hot water storage tank 4, the hot water in the hot water storage tank 4 is mixed with tap water and adjusted to an appropriate temperature. It is possible to cover the heat load. Moreover, in summer, surplus power is unlikely to be generated due to a large power load such as a cooler. Therefore, high temperature hot water is stored in the hot water storage tank 4 only by recovering the exhaust heat of the fuel cell 2 without using the surplus power heater 7 to cover most heat load, and the heat recovery efficiency is good.

  Further, when the exhaust heat recovery temperature is high, the heat storage density of the hot water storage tank 4 increases, so that the hot water storage tank 4 is unlikely to be fully stored and the heat recovery time can be lengthened. Therefore, the amount of fuel cell 2 that can be rated continuously operated to cover the power load is increased, and the consumption of commercial power can be reduced.

  On the other hand, for example, when the cogeneration system 1 is operated in winter, the flow rate is 15 kW, the thermal load is 70 MJ, the power generation amount of the fuel cell is constant at 600 W, and the power generation efficiency is 35%. When the exhaust heat recovery temperature is set to 80 ° C. by narrowing down, the case where the flow rate is increased and the exhaust heat recovery temperature is set to 60 ° C. is compared. When the exhaust heat recovery temperature is set to 80 ° C., the exhaust heat efficiency is 30%, whereas when the exhaust heat recovery temperature is set to 60 ° C., the exhaust heat efficiency is 40%.

  Under this condition, when the exhaust heat recovery temperature is 80 ° C., the energy saving rate is 19.7%, whereas when the exhaust heat recovery temperature is 60 ° C., the energy saving rate is 26.2%. Therefore, the energy saving rate increases by 6.5% when the exhaust heat recovery temperature is set to 60 ° C. Therefore, in winter, economy and energy saving can be improved by changing the exhaust heat recovery temperature from 80 ° C to 60 ° C.

The following can be considered for this reason.
When the exhaust heat recovery temperature is set low, the heat recovery rate decreases if the flow rate is increased. The outside air temperature surrounding the exhaust heat recovery line 5 is low in winter and the exhaust heat recovery temperature is low, so that a heat dissipation loss that occurs while hot water flows from the fuel cell 2 to the hot water storage tank 4 can be reduced. Although the heat load is 70 MJ, which is higher than in summer, the amount of heat supplied from the hot water storage tank 4 can be quickly replenished to the hot water storage tank 4 by increasing the heat recovery flow rate of hot water at 60 ° C. and storing it in the hot water storage tank 4. Therefore, by storing low temperature (60 ° C.) hot water in the hot water storage tank 4 at a large flow rate for a long time, the use frequency of the heat source unit 17 can be reduced and the primary energy consumption can be reduced.

  Here, when the exhaust heat recovery temperature is low, the heat storage density of the hot water storage tank 4 is reduced. However, since the heat load is large in winter, the hot water storage tank 4 is unlikely to be fully stored, and even if the exhaust heat recovery temperature is set low, it is possible to avoid stopping the fuel cell 2 as much as possible.

  In winter, there is less power load than in summer, and there is a high possibility that surplus power will be generated. However, if the surplus power heater 7 is heated by surplus power to increase the heat storage density of the hot water storage tank 4, the cogeneration system 1 can cover the thermal load while preventing the surplus power from leaking out.

  Therefore, the cogeneration system 1 determines the customer's heat load and power load that fluctuate according to the change of the season based on past operation results such as past heat load and power load and operation conditions such as outside air temperature and water temperature. The exhaust heat recovery temperature is predicted and changed, and the exhaust heat recovery temperature is appropriately corrected and changed on the prediction target day, so that economic efficiency and energy saving are dramatically improved. In particular, the cogeneration system 1 varies the exhaust heat recovery temperature by adjusting the flow rate so that there is little heat dissipation loss, so that the heat recovery efficiency is good and the economy and energy saving can be improved without waste.

<Modification>
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various application is possible.
For example, in the above embodiment, the fuel cell 2 is described as an example of the “generator”, but a gas engine may be used instead of the fuel cell 2.
For example, in the above embodiment, the pump is described as an example of the “flow rate adjusting unit”, but a flow rate adjusting valve may be used instead of the pump 6. Alternatively, a separate flow rate adjustment valve may be provided on the secondary side of the pump 6 so that the exhaust heat recovery temperature can be set finely by performing more precise flow rate adjustment.
For example, in the above embodiment, the exhaust heat recovery flow rate sensor 10 is disposed upstream of the pump 6 to measure the heat recovery flow rate. On the other hand, the flow rate may be measured by substituting the control value of the pump 6 with a flow rate value.
For example, in the said embodiment, the flow meter 18 was built in the heat source machine 17, and the thermal load was measured. On the other hand, instead of the flow meter, for example, a calorimeter may be built in the heat source unit 17. When using a calorimeter, it is possible to calculate the flow rate (heat load) by subtracting the temperature difference from the calorific value measured by the calorimeter.

It is a schematic structure figure of a cogeneration system concerning an embodiment of the present invention. It is a figure which shows the electric block structure of the controller shown in FIG. It is a flowchart of the driving | running plan program shown in FIG. It is a flowchart following the operation plan program shown in FIG. 4 is a sub-flowchart of the heat load prediction logic shown in FIG. 3. 4 is a sub-flowchart of a power generation output calculation logic shown in FIG. 3. It is a figure which shows an example of the heat dissipation rate memorize | stored in the heat dissipation rate memory | storage means shown in FIG. 3 is a flowchart of an operation control program shown in FIG.

Explanation of symbols

1 Cogeneration system 2 Fuel cell (generator)
4 Hot water storage tank 5 Waste heat recovery line 6 Pump (flow rate adjusting means)
7 Excess power heater 9 Waste heat temperature sensor (waste heat recovery temperature measuring means)
11 Hot water storage sensor (hot water storage temperature measuring means)
30 controller (operation result storage means, flow rate adjustment means, exhaust heat temperature setting means, heat load prediction means, exhaust heat recovery temperature correction means, power load / heat load prediction means, hot water time extraction means, surplus power heater use time determination means)
43 Heat dissipation rate storage means

Claims (7)

In a cogeneration system in which a generator and a hot water storage tank are connected by an exhaust heat recovery line, and hot water heated by heat generated by the generator during power generation is stored in a hot water storage tank,
Waste heat recovery temperature measuring means for measuring the temperature of hot water recovered in the hot water storage tank;
Flow rate adjusting means for adjusting the flow rate of circulating water to be circulated through the exhaust heat recovery line;
A flow rate control means for controlling the flow rate adjusting means so as to adjust the measured temperature measured by the exhaust heat recovery temperature measuring means to a set value of the exhaust heat recovery temperature;
A cogeneration system characterized by comprising: In the cogeneration system according to claim 1,
Driving performance storage means for storing past driving performance;
Exhaust heat recovery temperature setting means for setting a set value of the exhaust heat recovery temperature of the prediction target day based on the operation result stored in the operation result storage means and the operation condition of the prediction target day;
A cogeneration system characterized by comprising: In the cogeneration system according to claim 2,
A heat dissipation rate storage means for storing the heat dissipation rate generated during exhaust heat recovery in association with the water temperature or the outside air temperature and the exhaust heat recovery temperature;
The exhaust heat recovery temperature setting means extracts a heat release rate that matches the water temperature or outside temperature of the prediction target date and the exhaust heat recovery temperature from the heat release rate storage means, and includes the extracted heat release rate and includes the extracted heat release rate. A cogeneration system that sets the set value of the exhaust heat recovery temperature. In the cogeneration system according to claim 2 or claim 3,
A heat load prediction means for predicting the heat load on the prediction target day;
When the heat load predicted by the heat load prediction means deviates from the heat load generated on the prediction target day, the heat load after the time zone in which the deviation is detected is re-predicted, and the set value of the exhaust heat recovery temperature Exhaust heat recovery temperature correction means for correcting
A cogeneration system characterized by comprising: In the cogeneration system according to claim 4,
Hot water storage temperature measuring means for measuring the upper temperature of the hot water storage tank;
The exhaust heat recovery temperature correction means corrects the set value of the exhaust heat recovery temperature on the prediction target date to a value equal to or higher than the upper temperature of the hot water storage tank detected by the hot water storage temperature measurement means. . The cogeneration system according to any one of claims 1 to 5,
A cogeneration system comprising a surplus power heater installed on the exhaust heat recovery line and generating heat with surplus power generated by the generator. In the cogeneration system according to claim 6,
A power load / heat load prediction means for predicting a power load and a heat load on the prediction target day;
The amount of heat generated when the generator is operated under the set value of the exhaust heat recovery temperature on the prediction target day is compared with the heat load predicted by the power load / heat load prediction means, Hot water time extraction means for extracting the time zone where
The primary energy consumed when the power generation output of the generator is increased before the time zone extracted by the hot water time extraction means, and the set value of the exhaust heat recovery temperature on the prediction target day. Compared with the primary energy consumed when operating the generator, if the primary energy is smaller in the former case than in the latter case, the generator output is increased and surplus power is increased as the generator output increases. Surplus power heater use time determining means for determining a time zone in which the surplus power heater is used as a use time of the surplus power heater;
A cogeneration system characterized by comprising: