JP2007263010A - Co-generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a co-generation system capable of improving energy efficiency by effectively using exhaust heat collected from a co-generation device. <P>SOLUTION: This system is provided with a Ranking cycle circuit 20 having the steam generator 21 heating working solution S1 and generating steam, a steam turbine 22 driven by the steam S2, a condenser 23 cooling the steam S2 exhausted from the steam turbine S2 and condensing the same to working solution S1, and a solution pump 25 feeding working solution S1 condensed by the condenser 23 to the steam generator 21. The Ranking cycle circuit 20 uses working solution S1 having lower boiling point than stored hot water temperature of a hot water storage tank 10, and is constructed to operate by supply of hot water stored in the hot water storage tank 10 to the steam generator 21 as heat source. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cogeneration system including a combined heat and power device that generates heat and electric power, and a hot water storage tank that collects heat generated by the combined heat and power device and stores it as hot water.

In such a cogeneration system, a combined heat and power supply device such as an engine-driven generator or a fuel cell is provided, and the generated power of the combined heat and power supply device is supplied to a power consuming unit such as an electric device, and the generated heat of the combined heat and power device is, for example, The hot water heated by the heat is temporarily stored in a hot water storage tank and supplied to a heat consuming unit such as a hot water supply unit or a heating device.
And by providing such a cogeneration system in each home, etc., at least part of the power consumed in that home can be supplemented with the power generated by the combined heat and power supply device, so that the power received from the commercial power source is reduced. Moreover, since the heat generated at that time can be used as hot water, it is effective in terms of energy saving and economical efficiency.

  Such a cogeneration system may be configured to execute main operation control that causes the set output of the combined heat and power supply device to follow the power load in the power consumption unit. In the generation system, although the current power load can be covered by generated power, it does not correspond to the currently required current heat load, and there is a surplus heat state where heat is left in excess of the current heat load, Energy savings may deteriorate.

  Therefore, when it is predicted that a heat surplus state will occur with a relatively small heat load relative to the heat generated by the combined heat and power unit when the electric main operation control is executed, the output of the combined heat and power unit is reduced and the thermoelectric unit is controlled. In some cases, the heat surplus state is suppressed by suppressing the generation of heat in the co-feeding device (see, for example, Patent Document 1).

JP 2004-286008 A

  However, the actual heat load is often small relative to the amount of heat generated by the combined heat and power supply device, and unlike the prediction, it is often irregular. Therefore, it cannot be predicted that an excess heat state will occur in advance. In this case, an excessive heat state is generated, and the excess heat is discarded by a radiator or natural heat dissipation.

  Further, although the hot water tank is covered with a heat insulating material and kept warm, if the standing time is long, the hot water gradually radiates naturally and the temperature is lowered. And if the temperature of the hot water stored in the hot water storage tank falls below the hot water supply temperature, it is necessary to reheat the hot water with the auxiliary heat source device when the hot water is supplied, which may reduce the energy efficiency.

  The present invention has been made in view of the above problems, and an object thereof is to provide a cogeneration system capable of improving energy efficiency by effectively using exhaust heat recovered from a combined heat and power supply device. In the point.

To achieve the above object, a cogeneration system according to the present invention includes a combined heat and power device that generates heat and electric power, and a hot water storage tank that collects the heat generated by the combined heat and power device and stores it as hot water. The first characteristic configuration of the provided cogeneration system includes a steam generator for heating the working solution to generate steam, a steam turbine driven by the steam generated by the steam generator, and steam discharged from the steam turbine A Rankine cycle circuit comprising a condenser that cools the water and condenses into a working solution, and a solution pump that delivers the working solution condensed in the condenser to the steam generator,
The Rankine cycle circuit is configured to operate using a working solution having a boiling point lower than the hot water storage temperature of the hot water storage tank, and hot water stored in the hot water storage tank is supplied as a heat source of the steam generator. There is in point.

  According to the first characteristic configuration, by providing the Rankine cycle circuit, the working solution is evaporated in the steam generator, and in the steam turbine, shaft power is obtained by the steam, and a generator or the like is obtained by the shaft power. A so-called Rankine cycle in which the steam discharged after driving the steam turbine in the condenser is condensed into a working solution, and the working solution is supplied to the steam generator in the solution pump. Can be realized.

  Therefore, when there is a surplus heat state where the heat remains with respect to the current heat load, that is, when the waste heat of the combined heat and power supply device is recovered and heated to the hot water storage temperature and the hot water stored in the hot water tank is not effectively consumed. The Rankine cycle circuit is activated by supplying hot water stored in a hot water tank as a heat source to the steam generator in a state where the solution pump is operated, and can be used for power generation by the steam turbine. Axial output can be obtained. That is, the heat held by the hot water stored in the hot water tank can be used effectively, and the energy efficiency can be improved.

  Further, if the generator is driven by the shaft output of the steam turbine to generate power, for example, even when the combined heat and power device has a relatively large amount of exhaust heat, such as an engine-driven generator, The ratio of the power generation output to the sum of the power generation output and the heat output of the cogeneration system can be increased to be suitable for the actual power load ratio.

  In addition, the Rankine cycle circuit does not directly use hot water collected from the exhaust heat of the combined heat and power device as a heat source, but uses hot water stored in a hot water tank as a heat source. Regardless of the state, the hot water stored in the hot water tank can be used as a heat source. Therefore, the Rankine cycle circuit can be operated in a state where the cogeneration device is stopped, and the cogeneration device is stopped using the shaft output of the steam turbine while sufficiently eliminating the excess heat state. Even if it is, it can generate electricity.

  A second characteristic configuration of the cogeneration system according to the present invention is that the steam generator is provided in a hot water supply passage for supplying hot water from the hot water storage tank to a hot water supply section.

According to the second characteristic configuration, when hot water is supplied from the hot water storage tank to the hot water supply section through the hot water supply passage, the hot water passes through the steam generator. By operating the pump, the Rankine cycle circuit can be operated.
In addition, if hot water can be automatically drained at a specific hot water supply section, hot water in the hot water storage tank can be provided in the hot water supply path in accordance with the operation of the Rankine cycle circuit other than hot water supply according to the actual heat load. The hot water can be supplied in such a form that it is drained after passing through a steam generator.

3rd characteristic structure of the cogeneration system which concerns on this invention is comprised by the temperature stratification hot water type which the said hot water storage tank stores hot water in the form which forms temperature stratification,
Hot water extracted from above the hot water tank is passed through the steam generator and then returned to the lower side of the hot water tank so that the hot water is circulated.

  According to the third characteristic configuration, the hot water storage tank is configured in the above-described temperature stratification type, and high temperature hot water that is recovered to the hot water storage temperature is recovered above the hot water storage tank by recovering the exhaust heat of the combined heat and power device. A low temperature layer in which low temperature water supply exists can be formed below the hot water tank. And, by providing the hot water circulation circuit, hot water in the high temperature layer formed above the hot water tank is taken out and supplied as a heat source for the steam generator, and the Rankine cycle circuit is operated to be stored in the hot water tank. Energy efficiency can be achieved by effectively utilizing the heat of hot water. Furthermore, by returning the hot water discharged and discharged in the steam generator to the lower temperature layer in the hot water tank, the heat not consumed by the steam generator is returned to the hot water tank while suppressing waste of water. Thus, waste of heat can be suppressed.

The fourth characteristic configuration of the cogeneration system according to the present invention is a hot water storage state detection means for detecting a hot water storage state of the hot water tank,
And a control means for controlling the operation of the Rankine cycle circuit based on the detection result of the hot water storage state detection means.

  According to the fourth characteristic configuration, the control means automatically recognizes the hot water storage state of the hot water tank detected by the hot water storage state detection means, and recovers the exhaust heat of the combined heat and power supply device from the hot water storage state. If it can be determined that there is too much hot water stored in the hot water storage tank after being heated to the hot water storage temperature, there is a high possibility that it will be in a heat surplus state, and the hot water is supplied as a heat source for the steam generator to operate the Rankine cycle circuit. Thus, the energy efficiency can be reliably improved by controlling the operation of the Rankine cycle.

A cogeneration system according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, this cogeneration system includes an engine 1 a that generates heat and a generator 1 b that is driven by a shaft output of the engine 1 a and generates power as a combined heat and power generation device that generates power and heat. The engine drive generator 1 which consists of, the hot water storage tank 10 which collect | recovers the heat which the engine drive generator 1 generate | occur | produces, and stores it as hot water, and the operation control apparatus 70 which controls operation | movement are provided.

The engine 1a generates heat in a form in which high-temperature exhaust gas E is discharged into the exhaust passage 2 and in a form in which the engine coolant JW circulating in the coolant circulation path 3 is heated. The heat of the exhaust gas E is recovered and stored as hot water.
That is, the exhaust passage 2 is provided with an exhaust heat recovery heat exchanger 8 that heats hot water flowing inside through heat exchange with the exhaust gas E circulating outside, and the exhaust heat recovery heat exchanger 8 The heated hot water is supplied to the hot water tank 10.

  The hot water tank 10 is composed of a hermetically sealed tank having a heat insulating structure, and a water supply path 14 is connected to the lower side of the hot water tank 10 so that water in the hot water tank 10 is consumed. Water is supplied from the water supply channel 14 to the lower side of the hot water tank 10 so that the hot water tank 10 is always kept in a full state.

  Then, hot water taken out from the lower side of the hot water tank 10 is circulated through the exhaust heat recovery heat exchanger 8 and then returned to the upper side of the hot water tank 10. 7, a temperature sensor 9 for detecting the temperature of hot water supplied from the exhaust heat recovery heat exchanger 8 to the upper side of the hot water tank 10 on the upper side of the hot water tank 10 in the hot water circulation path 6. Is provided.

  The hot water tank 10 is configured in a temperature stratified hot water type that stores hot water in a state where temperature stratification is formed, and a high temperature heated by the exhaust heat recovery heat exchanger 8 is disposed above the hot water tank 10. A high temperature layer 10 a in which hot water exists is formed, and a low temperature layer 10 b in which low temperature water supplied through a water supply path 14 connected to the lower side exists is formed below the hot water storage tank 10.

Furthermore, in this temperature stratified hot water storage type hot water storage tank 10, a plurality of temperature sensors 17 for measuring the temperature of the hot water storage tank 10 are arranged at a plurality of locations along the vertical direction of the hot water storage tank 10. Thus, the temperature of the hot water at a plurality of locations along the vertical direction of the hot water tank 17 is measured.
And each measured temperature of this temperature sensor 17 will show hot values, so that hot water is stored in the state where hot water storage tank 10 forms temperature stratification, and what is arranged above will show these values. By using the measured temperature, for example, by knowing the arrangement region of the temperature sensor 17 indicating the measured temperature equal to or higher than a predetermined temperature, it is possible to know the hot water storage state of how much hot water of the predetermined temperature or higher is stored in the hot water storage tank 10. it can.
That is, the plurality of temperature sensors 17 function as hot water storage state detecting means for detecting the hot water storage state of the hot water storage tank 10.

  The cooling water circulation path 3 is provided with a circulation pump 4 for circulating the engine cooling water JW and a radiator 5 for air-cooling the engine cooling water JW. By operating the circulation pump 4 and the radiator 5, the engine 1a Is always cooled by supplying low-temperature engine cooling water JW.

The engine-driven generator 1 is configured to be able to adjust the power generation output of the power generator 1b by adjusting the output of the engine 1a, and the power generated by the engine-driven power generator 1 is controlled by an inverter for system linkage, etc. It is supplied to the power consumption unit and consumed at the same voltage and the same frequency as the received power received from the commercial power source.
In addition, when this generated power is larger than the actual power load in the power consuming unit, an electric heater (not shown) is provided to recover the surplus power by converting it into heat in order to prevent reverse power flow. Thus, the hot water stored in the hot water tank 10 can be heated.

A hot water supply path 11 leading to a hot water supply section 13 such as a hot water tap and a bathtub is connected to the upper side of the hot water storage tank 10, and hot water stored on the upper side of the hot water storage tank 10 is supplied to the hot water supply section 13 through the hot water supply path 11. Supplied.
The hot water supply path 11 is provided with an auxiliary heat source device 12 capable of heating the hot water flowing through the hot water supply path 11 and a temperature sensor 18 for detecting the temperature of the hot water supplied to the hot water supply section 13.

Next, output control of the engine 1a by the control device 70, hot water storage operation, and hot water supply operation will be described.
The control device 70 controls the output of the engine 1a so as to output electric power that follows the currently requested current power load when the engine-driven generator 1 operates.
Specifically, the control device 70 obtains the current power load and the power generation output for each relatively short predetermined output adjustment period such as one minute so that the power generation output is smaller than the current power load by a predetermined margin. The output of the engine 1a is set within the range from the minimum output to the maximum output.
The current power load is obtained by a power load meter provided in the power consuming unit, and the power generation output is obtained by adding power generation outputs of the generators 22a and 52a described later to the power generation output of the engine drive generator 1 described above. Required as an addition.
Further, the control device 70 is configured to operate the circulation pump 4 and the radiator 5 during operation of the engine-driven generator 1 to supply the engine 1a with low-temperature engine cooling water JW to cool the engine 1a. ing.

Then, the control device 70 operates the circulation pump 7 during the operation of the engine drive generator 1 as described above, and heats the hot water taken out from the lower side of the hot water storage tank 10 by the exhaust heat recovery heat exchanger 8. A hot water storage operation is performed in which hot water is circulated in the hot water circulation path 6 in a form that is later returned to the upper side of the hot water tank 10 to recover the exhaust heat of the engine-driven generator 1 and store the hot water in the hot water tank 10.
In this hot water storage operation, the control device 70 detects the hot water temperature returned to the upper side of the hot water tank 10 by the temperature sensor 9, and maintains the detected hot water temperature at a predetermined hot water storage temperature (for example, 80 ° C.). The circulation amount of hot water by the circulation pump 7 is controlled.
Therefore, hot water having a hot water storage temperature is stored in the high temperature layer 10a of the hot water storage tank 10.

On the other hand, when the hot water is consumed in the hot water supply unit 13, the control device 70 performs a hot water supply operation in which the temperature of the hot water supplied to the hot water supply unit 13 is set to a hot water temperature preset by the user. Execute.
In this hot water supply operation, the control device 70 detects the temperature of the hot water supplied to the hot water supply passage 11 by the temperature sensor 18, and when the detected hot water temperature is lower than the hot water supply temperature, the control device 70 turns off the auxiliary heat source unit 12. The hot water is operated and heated to the hot water supply temperature.
Furthermore, in this hot water supply operation, when the temperature of the hot water detected by the temperature sensor 18 is lower than the hot water temperature, the control device 70 mixes an appropriate amount of hot water with the hot water using a three-way valve (not shown). The unit 13 is configured to supply hot water having a hot water supply temperature.

  The basic configuration of the cogeneration system has been described above. A characteristic configuration that can improve the energy efficiency by effectively using the exhaust heat recovered from the engine-driven generator 1 will be described below.

  The cogeneration system is provided with a Rankine cycle circuit 20 configured to supply a heat source and generate a shaft output. The Rankine cycle circuit 20 heats the working solution S1 to generate steam S2. The steam generator 21, the steam turbine 22 driven by the steam generated by the steam generator 21, and the steam S2 discharged from the steam turbine 22 are cooled by heat exchange with a cooling medium such as air to recover the working solution S1. A condenser 23 for watering and a solution pump 25 for sending the working solution S1 condensed by the condenser 23 to the steam generator 21 are arranged. The working solution S1 condensed by the condenser 23 is once stored in the liquid receiver 24 and then supplied to the steam generator 21 through the solution pump 25.

  The Rankine cycle circuit 20 uses a working solution S1 such as ammonia or chlorofluorocarbon having a boiling point lower than the hot water storage temperature of the hot water tank 10 described so far, and is further stored in the high temperature layer 10a of the hot water tank 10. The hot water is supplied as a heat source for the steam generator 21 so as to operate.

  Further, the Rankine cycle circuit 20 is configured to generate power by driving the generator 22a with the shaft output generated by the steam turbine 22, and this generated output is the generated output of the engine-driven generator 1 described above. At the same time, it is supplied to the power consumption unit.

  Then, the control device 70 recovers the excess heat state with respect to the current heat load, that is, the hot water stored in the hot water storage tank 10 is recovered by recovering the exhaust heat of the engine-driven generator 1 and being heated to the hot water storage temperature. When the hot water stored in the hot water storage tank 10 is supplied to the steam generator 21 as a heat source, the solution pump 25 is operated and the steam turbine 22 generates the shaft output. It is configured to operate the Rankine cycle circuit 20 in a form to obtain and generate power, and by the operation of the Rankine cycle circuit 20, the heat held by the hot water stored in the hot water tank 10 is effectively utilized, Energy efficiency can be improved.

  The steam generator 21 of the Rankine cycle circuit 20 is provided in a hot water supply passage 11 for supplying hot water from the hot water storage tank 10 to the hot water supply section 13, and the hot water flowing through the hot water supply passage 11 is supplied to the Rankine cycle circuit 20 as a heat source. Will be.

  Furthermore, a return path 15 that communicates the outlet side of the steam generator 21 of the hot water supply path 11 and the lower side of the hot water storage tank 10, and hot water that has flowed out of the steam generator 21 in the hot water supply path 11 passes through the return path 15 to store hot water. A return pump 16 is provided for delivery to the lower side of the tank 10. That is, hot water that circulates hot water in such a form that the hot water taken out from above the hot water tank 10 is passed through the steam generator 21 and then returned to the lower side of the hot water tank 10 by the hot water supply path 11, the return path 15, and the return pump 16. A circulation circuit is configured.

  Furthermore, the control device 70 is configured to function as control means for controlling the operation of the Rankine cycle circuit 20 based on the detection results of the plurality of temperature sensors 17 provided in the hot water tank 10, and the details thereof will be described below. Add a description.

That is, the control device 70 recognizes the hot water storage state indicating how much hot water having a predetermined temperature (for example, 80 ° C.) or more is stored in the hot water storage tank 10 based on the detection result of the temperature sensor 17, and the hot water storage state is In a full state where a large amount of hot water is stored in 10, the solution pump 25 is operated to operate the Rankine cycle circuit 20.
Here, in the operation of the Rankine cycle circuit 20, when a hot water supply operation is performed, the hot water in the hot water storage tank 10 passes through the steam generator 21 and is supplied to the hot water supply unit 13. Hot water is supplied as a heat source.

On the other hand, in the operation of the Rankine cycle circuit 20, when the hot water supply operation is not performed, the return pump 16 is operated, the hot water taken out from above the hot water tank 10 is passed through the steam generator 21, and then the return path By operating the hot water circulation circuit in such a manner that the hot water circulation circuit is returned to the lower side of the hot water storage tank 10 through 15, the hot water is supplied to the steam generating unit 21 as a heat source, thereby suppressing waste of hot water.
Note that the hot water circulation circuit composed of the return path 15 and the return pump 16 is omitted, and the hot water is automatically drained in a specific hot water supply section 13 such as a bathtub, so that the Rankine cycle circuit 20 is operated. When the hot water supply operation is not performed, the hot water stored in the hot water storage tank 10 may be supplied to the steam generation unit 21 as a heat source by draining the hot water supply unit 13.

  Further, when the control device 70 predicts the heat load in advance and determines that hot water corresponding to the heat load is stored in the hot water storage layer 10, the control device 70 sets the Rankine cycle circuit 20 even if it is full. The Rankine cycle circuit 20 can also be configured to operate when a state in which the predicted heat load does not actually occur has elapsed for a long time.

  As described above, the controller 70 operates the Rankine cycle circuit 20 even when the hot water storage state of the hot water storage tank 10 is full and the exhaust heat of the engine-driven generator 1 cannot be recovered any more. Since the heat of the hot water stored in the hot water storage tank 10 can be consumed, it is possible to avoid a reduction in exhaust heat recovery efficiency. Furthermore, the power generation output of the generator 22a of the Rankine cycle circuit 20 is used in the power consumption unit together with the power generation output of the engine-driven generator 1 to improve energy efficiency.

  By operating the Rankine cycle circuit 20 described above, the ratio of the power generation output to the sum of the power generation output and the heat output in the cogeneration system is increased. On the other hand, when it is relatively large, each Rankine cycle circuit 20 may be appropriately operated.

  The cogeneration system is provided with a Rankine cycle circuit 50 that is different from the Rankine cycle circuit 20 described above, and details thereof will be described.

  That is, the Rankine cycle circuit 50 uses a working solution S1 such as ammonia or chlorofluorocarbon, like the Rankine cycle circuit 20 described above, and uses a steam generator 51, a steam turbine 52, a condenser 53, a liquid receiver 54, and a solution. The engine coolant JW on the inlet side of the radiator 5, which is disposed with a pump 55 and recovers the exhaust heat of the engine 1 a in the coolant circulation path 3 and has a relatively high temperature, is supplied as a heat source of the steam generator 51. It is configured to operate. Further, the Rankine cycle circuit 50 is also configured to generate power by driving the generator 52a by the shaft output of the steam turbine 52, and this power generation output is combined with the power generation output of the engine drive generator 1 described above. Supplied to the power consumption unit.

  The controller 70 is configured to operate the solution pump 55 so as to operate the Rankine cycle circuit 50 when the engine-driven generator 1 is operated. It is used in the power consuming unit together with the power generation output of the generator 1 to improve the energy efficiency.

  The engine coolant JW on the inlet side of the radiator 5 may be used as a heat source for heating the hot water stored in the hot water tank 10 without providing the Rankine cycle circuit 50.

In the above-described embodiment, the hot water storage tank 10 is configured as a temperature stratification type. However, the temperature of the hot water heated to the stored hot water temperature is not changed to a uniform temperature without forming a temperature stratification. It may be configured to simply store.
Moreover, in the said embodiment, although the engine drive generator 1 was illustrated as a combined heat and power apparatus, you may employ | adopt another forms of combined heat and power apparatuses, such as a fuel cell, as a combined heat and power apparatus.

  The cogeneration system according to the present invention can be effectively used as a cogeneration system capable of improving energy efficiency by effectively using the exhaust heat recovered from the combined heat and power supply device.

Schematic configuration diagram of cogeneration system

Explanation of symbols

1: Engine-driven generator (cogeneration device)
10: Hot water tank 11: Hot water supply path (hot water circulation circuit)
15: Return path (hot water circulation circuit)
16: Return pump (hot water circulation circuit)
17: Temperature sensor (hot water storage state detection means)
20: Rankine cycle circuit 21: Steam generator 22: Steam turbine 23: Condenser 70: Control device (control means)
S1: Working solution S2: Steam

Claims (4)

A cogeneration system comprising a combined heat and power device that generates heat and electric power, and a hot water storage tank that collects the heat generated by the combined heat and power device and stores it as hot water,
A steam generator that generates steam by heating the working solution, a steam turbine that is driven by the steam generated by the steam generator, and condensate that cools the steam discharged from the steam turbine and condenses it into the working solution. And a Rankine cycle circuit comprising a solution pump for delivering the working solution condensed by the condenser to the steam generator,
The Rankine cycle circuit is configured to operate using a working solution having a boiling point lower than the hot water storage temperature of the hot water storage tank, and hot water stored in the hot water storage tank is supplied as a heat source of the steam generator. Cogeneration system.   The cogeneration system according to claim 1, wherein the steam generator is provided in a hot water supply passage for supplying hot water from the hot water storage tank to a hot water supply section. The hot water storage tank is configured as a temperature stratified hot water storage type for storing hot water in a form that forms temperature stratification,
The cogeneration system according to claim 1, further comprising a hot water circulation circuit for circulating hot water in a form in which hot water taken out from above the hot water tank is passed through the steam generator and then returned to the lower side of the hot water tank. . Hot water storage state detection means for detecting the hot water storage state of the hot water storage tank;
The cogeneration system according to any one of claims 1 to 3, further comprising control means for controlling the operation of the Rankine cycle circuit based on a detection result of the hot water storage state detection means.

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