JP2014227903A - Rankine cycle device and cogeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new technology for preventing excessive heating of a working fluid.SOLUTION: A Rankine cycle device 18 includes: a main circuit 20; a cooling passage 33; and a control valve 35. The main circuit 20 includes: an evaporator 24; an expander 21; a condenser 22; and a pump 23 and is formed by annularly connecting these components in the written order. The cooling passage 33 is branched from the main circuit 20 between the pump 23 and the evaporator 24. The cooling passage 33 is formed so that a working fluid flowing in the evaporator 24 is cooled by a working fluid discharged from the pump 23. The control valve 35 is provided at the cooling passage 33 and controls the flow of the working fluid in the cooling passage 33.

Description

  The present invention relates to a Rankine cycle device and a combined heat and power system.

  As is well known to those skilled in the art, the Rankine cycle is the theoretical cycle of a steam turbine. Research and development on Rankine cycle has been done for a long time. On the other hand, as described in Patent Document 1, research and development on a combined heat and power system using Rankine cycle is also being conducted. A combined heat and power system (CHP system: Combined Heat and Power System) is a system configured to simultaneously obtain multiple forms of energy such as heat and power from a single or multiple resources. In recent years, not only large-scale CHP systems but also CHP systems that can be installed in relatively small facilities such as hospitals, schools, and libraries, and CHP systems for general households (so-called micro CHP) have attracted attention. Yes.

US Patent Application Publication No. 2003/0213854

  The CHP system of Patent Document 1 is configured to obtain electric power by using combustion gas generated by a gas boiler as thermal energy for a Rankine cycle device. Further, Patent Document 1 discloses a structure of an evaporator for preventing a gas-phase organic working fluid from being excessively heated by a boiler.

  The evaporator disclosed in Patent Document 1 may certainly be effective when the Rankine cycle apparatus is in a stable operating state. However, a technique that can prevent the working fluid from being heated excessively regardless of the operating state of the Rankine cycle device is desired.

  An object of this invention is to provide the novel technique for preventing that a working fluid is overheated.

That is, this disclosure
A main circuit formed by having an evaporator, an expander, a condenser and a pump, and these components are connected in a ring in this order;
A cooling path configured to branch from the main circuit between the pump and the evaporator, and to cool the working fluid flowing through the evaporator with the working fluid discharged from the pump;
A control valve provided in the cooling path and controlling the flow of the working fluid in the cooling path;
A Rankine cycle device is provided.

  According to said technique, it can prevent that a working fluid is heated too much.

1 is a configuration diagram of a CHP system according to a first embodiment of the present invention. Configuration diagram of the evaporator of Rankine cycle device shown in FIG. Configuration diagram of another evaporator of Rankine cycle apparatus shown in FIG. Flow chart of control executed in the CHP system shown in FIG. Configuration diagram of CHP system according to second embodiment of the present invention The block diagram of the evaporator of Rankine cycle apparatus shown in FIG. Configuration diagram of another evaporator of Rankine cycle apparatus shown in FIG. Configuration diagram of CHP system according to third embodiment of the present invention Flow chart of control executed in the CHP system shown in FIG. Configuration diagram of evaporator of conventional Rankine cycle equipment

  If excessive heat exchange occurs between a high-temperature fluid such as combustion gas generated by a gas burner and a gas-phase working fluid in the evaporator of the Rankine cycle system, the working fluid will be thermally decomposed, the lubricating oil will deteriorate, etc. There is a risk of malfunction. This problem becomes prominent when an organic working fluid is used and when an expander that requires lubricating oil is used.

  In order to avoid the above problem, Patent Document 1 proposes an evaporator 104 having a structure shown in FIG. The evaporator 104 is provided with a working fluid inlet 110A on the downstream side of a flow path 104C for high-temperature fluid (combustion gas generated by a burner). The working fluid that flows into the distal portion 104D from the inlet 110A exchanges heat with the hot fluid in the form of a counterflow. The working fluid is then sent via the connecting pipe 104H to the proximal portion 104E disposed upstream of the hot fluid. In the proximal portion 104E, the working fluid flows through the first section 104E1 and the second section 104E2 in this order. That is, at the proximal portion 104E, the working fluid exchanges heat with the hot fluid in a parallel flow manner. The working fluid outlet 110C is provided near the center of the enclosure 104A. In addition, the numerical value in a heat exchanger tube (circle) represents the example of the temperature (Fahrenheit) of a working fluid.

  According to the evaporator 104 shown in FIG. 9, it is speculated that it is possible to prevent excessive heating of the working fluid. This is because the working fluid is assumed to be in a liquid phase state at the distal portion 104D, a liquid phase state or a gas-liquid two-phase state in the first section 104E1, and a gas-liquid two-phase state or a gas phase state in the second section 104E2. Because. However, this estimation is only an estimation when the Rankine cycle apparatus is in a stable operating state. For example, when the circulation amount of the working fluid is reduced in accordance with a change in power generation demand, the working fluid may be in a gas phase state in the first section 104E1 as early as possible. As a result, in the first section 104E1, the gas phase working fluid may be excessively heated.

  Reducing the burner's heating power in accordance with the circulation amount of the working fluid is one effective means, but it is not always sufficient from the viewpoint of responsiveness. In recent years, attempts have been made to use solid fuel such as biomass and wood pellets instead of gas. The combustion of fuel in a pellet boiler is not as stable as a gas boiler. Naturally, pellet boilers are not suitable for suddenly raising or lowering firepower. Therefore, a technique for preventing the working fluid from being heated excessively becomes more important.

In view of the above circumstances, the first aspect of the present disclosure is:
A main circuit formed by having an evaporator, an expander, a condenser and a pump, and these components are connected in a ring in this order;
A cooling passage configured to branch from the main circuit between the pump and the evaporator and to cool the working fluid flowing through the evaporator with the working fluid discharged from the pump;
A control valve provided in the cooling path and controlling the flow of the working fluid in the cooling path;
A Rankine cycle device is provided.

  According to the Rankine cycle device, the working fluid flowing through the evaporator is cooled by the working fluid flowing through the main circuit between the pump and the evaporator. Thereby, it can prevent that a working fluid is heated too much with an evaporator. The flow of the working fluid in the cooling path is controlled by the control valve. Accordingly, it is possible to avoid excessive cooling of the working fluid flowing through the evaporator. As a result, it is possible to supply a working fluid having a desired degree of superheat to the expander while preventing problems such as thermal decomposition of the working fluid.

  According to a second aspect of the present disclosure, in addition to the first aspect, the temperature of the working fluid flowing through the evaporator is lowered by mixing the working fluid discharged from the pump and the working fluid flowing through the evaporator. Thus, a Rankine cycle device is provided in which the cooling path is connected to the evaporator. According to the second aspect, since the low temperature working fluid is mixed with the high temperature working fluid, the temperature of the working fluid can be quickly lowered in the evaporator. This increases the reliability of the Rankine cycle device.

  According to a third aspect of the present disclosure, in addition to the second aspect, the evaporator includes an upstream portion relatively close to the inlet with respect to an intermediate point of a flow path from the inlet to the outlet of the evaporator, and the outlet. A Rankine cycle device having a downstream portion relatively close to the cooling portion, wherein the cooling path is connected to the downstream portion. When a cooling path is connected to the downstream portion, the low-temperature working fluid can be accurately supplied to a place where excessive heating of the working fluid is expected to occur.

  According to a fourth aspect of the present disclosure, in addition to the second or third aspect, the evaporator is disposed in a flow path of a thermal fluid for heating the working fluid and is not in contact with the thermal fluid. A Rankine cycle device having an isolation part located at a location isolated from the flow path of the thermal fluid so as to prevent contact with the thermal fluid, wherein the cooling path is connected to the isolation part provide. According to the 4th aspect, it can prevent that the temperature of the working fluid in a cooling path rises too much.

  According to a fifth aspect of the present disclosure, in addition to the first aspect, the cooling path flows through the evaporator by exchanging heat between the working fluid discharged from the pump and the working fluid flowing through the evaporator. Provided is a Rankine cycle device having a heat exchange part for indirectly cooling the working fluid. According to the fifth aspect, since heat is only transferred in the heat exchanging section, there is a possibility that the control of the Rankine cycle apparatus is likely to shift to the steady control after starting the cooling using the working fluid discharged from the pump.

  The sixth aspect of the present disclosure provides, in addition to the fifth aspect, a Rankine cycle device in which the cooling path joins the main circuit between the expander and the condenser. According to such a structure, a working fluid flows smoothly into a cooling path by opening a control valve.

  According to a seventh aspect of the present disclosure, in addition to the fifth aspect, a Rankine cycle device is provided in which the cooling path is joined to the main circuit between the pump and the evaporator. According to the seventh aspect, the flow rate of the working fluid in the evaporator does not change before and after opening the control valve. Specifically, the entire amount of working fluid passes through the inlet of the evaporator. Therefore, a phenomenon in which the working fluid is excessively heated in the evaporator due to a decrease in the flow rate of the working fluid cannot essentially occur.

  According to an eighth aspect of the present disclosure, in addition to any one of the first to seventh aspects, the working fluid flowing in the main circuit between the pump and the evaporator, the expander, and the condenser The Rankine cycle device further includes a reheater for exchanging heat with the working fluid flowing through the main circuit between the two. The reheater improves the power generation efficiency of the Rankine cycle device.

  According to a ninth aspect of the present disclosure, in addition to the first aspect, the working fluid that flows in the main circuit between the pump and the evaporator, and the main circuit between the expander and the condenser flow. And a reheater for exchanging heat with the working fluid, wherein the cooling path exchanges heat between the working fluid discharged from the pump and the working fluid flowing through the evaporator. A heat exchanging unit that indirectly cools the flowing working fluid; and (a) the cooling path joins the main circuit between the expander and the reheater, (b) the Joining the main circuit between the reheater and the condenser, (c) joining the main circuit between the pump and the reheater, or (d) the reheating. A Rankine cycle device that joins the main circuit between the evaporator and the evaporator .

  According to the requirement (a), heat can be transferred from the working fluid heated in the heat exchange section to the working fluid on the high-pressure side of the Rankine cycle through the reheater. According to the requirement (b), since the amount of heat exchange in the reheater is reduced, a lower temperature working fluid can be supplied to the evaporator. According to requirement (c), the working fluid is returned to the vicinity of the reheater inlet after flowing through the cooling path. That is, the flow rate of the working fluid in the reheater and the evaporator does not depend on the flow rate of the working fluid in the cooling path. If the control valve is opened and the second control valve is closed, the entire amount of working fluid discharged from the pump is guided to the cooling path. In this case, the maximum cooling capacity is exhibited in the cooling unit. Despite the use of an indirect cooling method, it is possible to expect cooling with good response. According to the requirement (d), the working fluid heated in the heat exchange part of the cooling path is supplied to the evaporator bypassing the reheater. Therefore, it can suppress that the heat given to the working fluid in the heat exchange part is released to the surroundings. This means efficient recovery of thermal energy and contributes to improvement in utilization efficiency of thermal energy.

  In a tenth aspect of the present disclosure, in addition to the fifth aspect, the cooling path branches from the main circuit at a branch position between the pump and the evaporator, and joins the main circuit at an arbitrary joining position. The Rankine cycle device further includes a second control valve that is provided in the main circuit between the branch position and the merge position and that controls the flow of the working fluid in the main circuit. Providing equipment. By using the control valve and the second control valve, an appropriate amount of working fluid can be guided to the cooling path.

An eleventh aspect of the present disclosure includes any one of the Rankine cycle apparatuses according to the first to tenth aspects;
A heat medium circuit through which a heat medium as a low-temperature heat source for cooling the working fluid flows in the condenser of the Rankine cycle device;
A combined heat and power system is provided.

  If the Rankine cycle device according to any one of the first to tenth aspects is used, a highly reliable combined heat and power system can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the following embodiment.

(First embodiment)
As shown in FIG. 1, a combined heat and power system 100 (hereinafter referred to as a CHP system) of the present embodiment includes a boiler 10, a Rankine cycle device 18, a heat medium circuit 30, and a control device 50. The CHP system 100 is configured so that hot water and electric power can be obtained simultaneously or independently using thermal energy generated by the boiler 10. “Simultaneously” means that electric power can be supplied while supplying hot water.

  The boiler 10 includes a combustion chamber 12 and a combustor 14. An exhaust port is provided in the upper part of the combustion chamber 12. The combustor 14 is a heat source that generates the combustion gas G, and is disposed inside the combustion chamber 12. The combustion gas G generated by the combustor 14 travels upward in the internal space of the combustion chamber 12 and is discharged to the outside through the exhaust port. If the combustor 14 that generates the combustion gas G is used as a heat source of the CHP system 100, high-temperature heat energy can be easily obtained. As a result, the power generation efficiency of the Rankine cycle device 18 can be improved. Other devices such as a blower may be disposed inside the boiler 10.

  The boiler 10 is, for example, a gas boiler. When the boiler 10 is a gas boiler, the combustor 14 is supplied with a fuel gas such as natural gas or biogas. The combustor 14 generates high-temperature combustion gas G by burning fuel gas. However, the boiler 10 may be another boiler such as a pellet boiler. In this case, the combustor 14 is supplied with solid fuel such as wood pellets.

  The Rankine cycle device 18 includes a main circuit 20, a cooling path 33, and a control valve 35. The main circuit 20 includes an expander 21, a condenser 22, a pump 23, and an evaporator 24. The main circuit 20 is formed by connecting these components in a ring shape in the above order by piping. The Rankine cycle device 18 further includes a reheater 25.

  The cooling path 33 branches from the main circuit 20 between the outlet of the pump 23 and the inlet of the evaporator 24 and is connected to the evaporator 24. The cooling path 33 can be formed by a pipe having the same inner diameter as the pipe of the main circuit 20. The control valve 35 is provided in the cooling path 33 and plays a role of controlling the flow (flow rate) of the working fluid in the cooling path 33. The control valve 35 may be a valve (flow control valve) that can adjust the flow rate of the working fluid in the cooling passage 33 by changing the opening degree, or may be an on-off valve. A combination of a pressure reducing component such as a capillary tube and an on-off valve may be used as the control valve 35. When the control valve 35 is opened, the low-temperature working fluid discharged from the pump 23 is supplied to the evaporator 24 through the cooling path 33. The low temperature working fluid is mixed with the high temperature working fluid in the evaporator 24. As a result, the temperature of the working fluid flowing through the evaporator 24 decreases. That is, the cooling path 33 is a flow path configured to cool the working fluid flowing through the evaporator 24 with the working fluid discharged from the pump 23.

  If the cooling passage 33 and the control valve 35 are appropriately used, it is possible to prevent the working fluid from being excessively heated by the evaporator 24. The flow of the working fluid in the cooling passage 33 can be controlled by the control valve 35. Therefore, it is possible to avoid the working fluid flowing through the evaporator 24 from being excessively cooled. As a result, a working fluid having a desired degree of superheat can be supplied to the expander 21 while preventing problems such as thermal decomposition of the working fluid. Since the low-temperature working fluid is mixed with the high-temperature working fluid, the temperature of the working fluid can be quickly lowered in the evaporator 24. Thereby, the reliability of Rankine cycle device 18 increases.

  For example, when the boiler 10 is a pellet boiler, it is difficult to suddenly reduce the amount of combustion gas G generated or to suddenly lower the temperature of the combustion gas G. Further, factory exhaust gas may be used as a thermal fluid for heating the working fluid. It is difficult to adjust the temperature of the exhaust gas. According to the present embodiment, the temperature of the working fluid can be quickly lowered in the evaporator 24 by mixing the low temperature working fluid with the high temperature working fluid. Therefore, this embodiment is not easily affected by the type of thermal fluid, the generation method thereof, and the like.

  In the present embodiment, the cooling path 33 branches from the main circuit 20 between the outlet of the pump 23 and the inlet of the reheater 25 (branching position K1). Therefore, a lower temperature working fluid can be supplied to the evaporator 24. However, the cooling path 33 may be branched from the main circuit 20 between the outlet of the reheater 25 and the inlet of the evaporator 24.

  The expander 21 converts the expansion energy of the working fluid into rotational power by expanding the working fluid. A generator 26 is connected to the rotating shaft of the expander 21. The generator 26 is driven by the expander 21. The expander 21 is, for example, a positive displacement or turbo expander. Examples of positive displacement expanders include scroll expanders, rotary expanders, screw expanders, and reciprocating expanders. The turbo expander is a so-called expansion turbine.

  As the expander 21, a positive displacement expander is recommended. In general, a positive displacement expander exhibits higher expander efficiency over a wider range of rotation speeds than a turbo expander. For example, a positive displacement expander can be operated at a rotational speed that is half or less than the rated rotational speed while maintaining high efficiency. That is, the power generation amount can be reduced to half or less of the rated power generation amount while maintaining high efficiency. Since the positive displacement expander has such characteristics, if the positive displacement expander is used, it is possible to flexibly cope with changes in the amount of power generated due to changes in heat demand. In addition, the amount of power generation can be increased or decreased while maintaining high efficiency in response to changes in power demand.

  The condenser 22 cools the working fluid and heats the water by exchanging heat between the water in the heat medium circuit 30 and the working fluid discharged from the expander 21. As the condenser 22, a known heat exchanger such as a plate heat exchanger or a double tube heat exchanger can be used. The type of the condenser 22 is appropriately selected according to the type of the heat medium in the heat medium circuit 30. When the heat medium in the heat medium circuit 30 is a liquid such as water, a plate heat exchanger or a double pipe heat exchanger can be suitably used for the condenser 22. When the heat medium in the heat medium circuit 30 is a gas such as air, a finned tube heat exchanger can be suitably used for the condenser 22.

  The pump 23 sucks and pressurizes the working fluid flowing out from the condenser 22, and supplies the pressurized working fluid to the evaporator 24. As the pump 23, a general positive displacement type or turbo type pump can be used. Examples of the positive displacement pump include a piston pump, a gear pump, a vane pump, and a rotary pump. Examples of the turbo type pump include a centrifugal pump, a mixed flow pump, and an axial flow pump.

  The evaporator 24 is a heat exchanger that absorbs thermal energy of the combustion gas G generated by the boiler 10. The evaporator 24 is, for example, a fin tube heat exchanger, and is disposed inside the boiler 10 so as to be positioned directly above the combustor 14. The combustion gas G generated in the boiler 10 and the working fluid of the Rankine cycle device 18 exchange heat in the evaporator 24. As a result, the working fluid is heated and evaporated.

  The reheater 25 operates through the main circuit 20 between the outlet of the pump 23 and the inlet of the evaporator 24 and through the main circuit 20 between the outlet of the expander 21 and the inlet of the condenser 22. Heat exchange with fluid. The reheater 25 improves the power generation efficiency of the Rankine cycle device 18. As the reheater 25, a known heat exchanger such as a plate heat exchanger or a double tube heat exchanger can be used.

  An organic working fluid can be suitably used as the working fluid of the Rankine cycle device 18. Organic working fluids include halogenated hydrocarbons, hydrocarbons, alcohols and the like. Examples of the halogenated hydrocarbon include R-123, R-245fa, R-1234ze, and the like. Examples of the hydrocarbon include alkanes such as propane, butane, pentane, and isopentane. Examples of alcohol include ethanol. These organic working fluids may be used alone or in combination of two or more. There is a possibility that an inorganic working fluid such as water, carbon dioxide, or ammonia can be used as the working fluid.

  The heat medium circuit 30 is a circuit through which water (heat medium) as a low-temperature heat source for cooling the working fluid of the Rankine cycle device 18 flows in the condenser 22, and is connected to the condenser 22. Water in the heat medium circuit 30 is heated by the working fluid discharged from the expander 21. The heat medium circuit 30 is provided with a pump 31 and a radiator 32. The radiator 32 is, for example, a part of an indoor floor heating facility. Hot water produced by the condenser 22 is supplied to the radiator 32 by the pump 31 and used for indoor heating. That is, in this embodiment, the heat medium circuit 30 is a hot water heating circuit. When the city water is heated by the condenser 22, the hot water produced by the condenser 22 can be used for hot water supply. By effectively utilizing the low-temperature exhaust heat of the working fluid, the overall thermal efficiency of the Rankine cycle device 18 can be improved.

  As in this embodiment, when the heat medium to be heated through the heat medium circuit 30 is a liquid such as water or brine, the heat medium circuit 30 can be formed by piping. On the other hand, when the heat medium to be heated through the heat medium circuit 30 is a gas such as air, the heat medium circuit 30 can be formed by an air passage or a duct for flowing the gas. Hot air produced by the condenser 22 is supplied indoors and used for indoor heating.

  The hot water generated in the heat medium circuit 30 can be supplied to other facilities such as a shower, a faucet, and a hot water storage tank. That is, the heat medium circuit 30 may be used for the purpose of reheating low temperature hot water, or may be used for the purpose of heating city water. Note that the CHP system 100 may be configured to stop supplying hot water and supply only electric power.

  The control device 50 controls controlled objects such as the pump 23, the pump 31, the combustor 14, the generator 26, and the control valve 35. As the control device 50, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device and the like can be used. The control device 50 stores a program for appropriately operating the CHP system 100.

  The Rankine cycle device 18 further includes a pressure sensor 38 and a temperature sensor 39. The pressure sensor 38 is disposed near the outlet of the pump 23. The place where the working fluid exhibits the highest pressure in the main circuit 20 is the outlet of the pump 23. The pressure sensor 38 detects the pressure of the working fluid discharged from the pump 23, that is, the pressure on the high pressure side of the Rankine cycle. The pressure detected by the pressure sensor 38 is the maximum pressure of the working fluid in the Rankine cycle. The temperature sensor 39 is disposed near the outlet of the evaporator 24. A temperature sensor 39 detects the temperature of the working fluid flowing out of the evaporator 24. The temperature detected by the temperature sensor 39 is the maximum temperature of the working fluid in the Rankine cycle. Detection signals from the pressure sensor 38 and the temperature sensor 39 are input to the control device 50.

  The pressure sensor 38 is disposed in the main circuit 20 between the outlet of the pump 23 and the inlet of the evaporator 24. Specifically, the pressure sensor 38 is disposed in the main circuit 20 between the branch position K1 and the inlet of the reheater 25. The branch position K1 is a position corresponding to the upstream end of the cooling path 33. However, the pressure sensor 38 may be disposed in the main circuit 20 between the outlet of the reheater 25 and the inlet of the evaporator 24. Specifically, the temperature sensor 39 is disposed in the main circuit 20 between the outlet of the evaporator 24 and the inlet of the expander 21. In order to avoid the influence of the combustion gas G, it is desirable that the temperature sensor 39 is located outside the boiler 10.

  The control valve 35 is controlled based on the temperature detected by the temperature sensor 39. Specifically, the control valve 35 is opened and closed based on the temperature detected by the temperature sensor 39. Alternatively, the opening degree of the control valve 35 is adjusted based on the temperature detected by the temperature sensor 39. The temperature detected by the temperature sensor 39 is the highest temperature in the Rankine cycle. Therefore, when the temperature detected by the temperature sensor 39 exceeds the predetermined upper limit temperature, the control valve 35 is opened, and the low-temperature working fluid discharged from the pump 23 is supplied to the evaporator 24 through the cooling path 33. Can do. Thereby, it is possible to prevent the working fluid from being excessively heated in the evaporator 24. Since such control is very simple, it is excellent in terms of ensuring the reliability of the Rankine cycle device 18. Further, the load on the control device 50 is reduced. The “upper limit temperature” is set to a sufficiently low temperature in order to prevent problems such as thermal decomposition of the working fluid. For example, when the working fluid is R-245fa, the upper limit temperature can be set to around 200 ° C.

  Next, the detailed structure of the evaporator 24 will be described.

  As shown in FIG. 2A, in this embodiment, the evaporator 24 is a finned tube heat exchanger having a plurality of fins 27 and a plurality of heat transfer tubes 28. The plurality of fins 27 are arranged in the horizontal direction so that their front and back surfaces are parallel to the vertical direction. A space formed between the fin 27 and the fin 27 forms an exhaust path for the combustion gas G (high temperature fluid). The plurality of heat transfer tubes 28 are arranged in a plurality of stages in the flow direction (height direction) of the combustion gas G to be heat-exchanged with the working fluid. The plurality of heat transfer tubes 28 are connected to each other so as to form one flow path by a plurality of bend tubes 29 provided at both ends in the longitudinal direction of the heat transfer tubes 28. However, it is not essential that a single flow path is formed by all the heat transfer tubes 28. Two or more flow paths may be formed in parallel by using a known component such as a distributor.

  The working fluid is in a liquid phase immediately after flowing into the evaporator 24 and exhibits the lowest temperature. As the evaporator 24 flows from the inlet toward the outlet and is heated by the combustion gas G, the working fluid evaporates. At the outlet of the evaporator 24, the working fluid is in the gas phase and its temperature is the highest. Specifically, the closer to the outlet of the evaporator 24, the higher the temperature of the working fluid. If excessive heat exchange occurs between the combustion gas G and the working fluid in the evaporator 24, the temperature of the working fluid becomes too high near the outlet of the evaporator 24. As a result, problems such as thermal decomposition of the working fluid and deterioration of the lubricating oil may occur. In order to cope with such a problem, the Rankine cycle device 18 uses the cooling path 33 and the control valve 35.

  As shown in FIG. 2A, the evaporator 24 includes an upstream portion 24s and a downstream portion 24t. The upstream portion 24 s is a portion that is relatively close to the inlet with reference to the midpoint of the flow path from the inlet to the outlet of the evaporator 24. The downstream portion 24t is a portion that is relatively close to the outlet with respect to the intermediate point. The cooling path 33 is connected to the downstream portion 24t. It is assumed that the working fluid is overheated in the downstream portion 24t. When the cooling path 33 is connected to the downstream portion 24t, the low-temperature working fluid can be accurately supplied to a portion where excessive heating of the working fluid is predicted to occur.

  The evaporator 24 is disposed in the flow path of the combustion gas G for heating the working fluid. In the present embodiment, the flow path of the combustion gas G is formed by the internal space of the combustion chamber 12. Further, the evaporator 24 has an isolation part 24 a located at a location isolated from the internal space of the combustion chamber 12 so as not to contact the combustion gas G. The isolator 24 a is typically located outside the combustion chamber 12. The cooling path 33 is connected to the isolation part 24a. The isolation part 24 a is composed of two (a plurality of) heat transfer tubes 28 extending to the outside of the combustion chamber 12 and at least one bend tube 29 connecting the two heat transfer tubes 28. A cooling path 33 is connected to the bend pipe 29 in the isolation part 24a. The working fluid discharged from the pump 23 is supplied to the separator 24 a of the evaporator 24, bypassing the reheater 25 and the upstream portion 24 s of the evaporator 24 through the cooling path 33. Thereby, the working fluid flowing through the evaporator 24 can be cooled.

  The isolation part 24 a is located near the outlet of the evaporator 24. In the present embodiment, the isolation portion 24 a is included in the downstream portion 24 t of the evaporator 24. Specifically, the position of the isolation portion 24 a in the evaporator 24 is determined so that the low-temperature working fluid is injected into the heat transfer tube 28 at the most downstream stage of the evaporator 24. The temperature of the working fluid rises rapidly at a position close to the outlet of the evaporator 24. Therefore, if the isolation part 24a is located near the outlet of the evaporator 24, it is possible to effectively prevent the working fluid from being heated excessively.

  When the control valve 35 is closed, the working fluid stays in the cooling path 33 between the downstream end of the cooling path 33 and the control valve 35. In this embodiment, since the isolation part 24a is located outside the combustion chamber 12, the combustion gas G cannot directly contact the isolation part 24a. That is, the separator 24 a is not directly heated by the combustion gas G, and the working fluid retained in the cooling path 33 is not directly heated by the combustion gas G. Therefore, it is possible to prevent the temperature of the working fluid from rising excessively in the cooling path 33.

  However, it is not essential that a part of the evaporator 24 is located outside the combustion chamber 12. A cooling path 33 may join the evaporator 24 inside the combustion chamber 12. As shown in FIG. 2B, when the isolation part 24a is located inside the combustion chamber 12, the isolation part 24a may be covered with the partition wall 12a. The partition wall 12 a prevents or prevents the combustion gas G from coming into direct contact with the cooling path 33. According to such a configuration, the same effect as when the cooling path 33 is connected to the evaporator 24 outside the combustion chamber 12 can be obtained.

  Next, the control executed by the control device 50 will be described with reference to the flowchart of FIG. The flowchart of FIG. 3 represents control for preventing the working fluid flowing through the evaporator 24 from being heated excessively. This control is executed, for example, with the start of operation of the Rankine cycle device 18.

  First, the temperature Th of the working fluid is detected by the temperature sensor 39 (step S1). The temperature Th is the temperature of the working fluid at the outlet of the evaporator 24 and is the highest temperature of the working fluid in the main circuit 20. Next, based on the detected temperature Th, it is determined whether the working fluid is excessively heated by the evaporator 24 (step S2). Specifically, it is determined whether the detected temperature Th is equal to or higher than the upper limit. As described above, the upper limit of the temperature Th is set to a sufficiently low temperature to prevent problems such as thermal decomposition of the working fluid. When the temperature Th is equal to or higher than the upper limit, that is, when the temperature Th of the working fluid is too high, control for lowering the temperature of the working fluid flowing through the evaporator 24 is performed.

  Before the control for lowering the temperature of the working fluid flowing through the evaporator 24 is performed, the pressure Ph of the working fluid at the outlet of the pump 23 is detected by the pressure sensor 38. As necessary, the controller 50 grasps the rotational speed fp (operating frequency) of the pump 23 and the rotational speed fe (operating frequency) of the expander 21 (step S3).

  Next, as a control for lowering the temperature of the working fluid flowing through the evaporator 24, the amount of combustion heat of the combustor 14 is lowered (step S4). As a method for reducing the amount of combustion heat, it is possible to reduce the amount of fuel supplied to the combustor 14. When a blower is provided in the boiler 10, the amount of combustion heat can be reduced by reducing the amount of air blown.

  Next, it is determined whether the rotation speed fp of the pump 23 is less than the upper limit (step S5). If the rotational speed fp of the pump 23 is less than the upper limit, the rotational speed of the pump 23 is increased to increase the circulation amount of the working fluid in the main circuit 20 (step S6). By increasing the circulation amount of the working fluid, it is possible to avoid a significant decrease in the amount of working fluid supplied to the inlet of the evaporator 24 when the control valve 35 is opened. In this way, it is possible to prevent the working fluid from being heated excessively upstream of the isolation part 24a.

  In addition, if the circulation amount of the working fluid is increased by increasing the rotation speed of the pump 23, the amount of the working fluid flowing into the expander 21 is also increased. As a result, the rotation speed of the expander 21 increases. If the rotation speed of the expander 21 exceeds the upper limit, it becomes a factor that reduces the reliability of the expander 21. Accordingly, in step S7, it is determined whether or not the rotational speed fe of the expander 21 is larger than the upper limit. When the rotational speed fe of the expander 21 is larger than the upper limit, the rotational speed of the expander 21 is decreased (step S8). As a method for reducing the rotation speed of the expander 21, increasing the load on the generator 26 can be mentioned. Moreover, the bypass flow path which bypasses the expander 21 and the flow control valve arrange | positioned at the bypass flow path may be provided. If the working fluid is caused to flow through the bypass flow path by controlling the flow rate control valve, the rotational speed fe of the expander 21 can be lowered. The upper limit of the rotation speed fp of the pump 23 is set in consideration of the capacity of the prime mover of the pump 23, for example. The upper limit of the rotational speed fe of the expander 21 is set to a sufficiently low rotational speed to ensure the reliability of the expander 21.

  After adjusting the rotational speed of the pump 23 and the rotational speed of the expander 21, the control valve 35 is opened (step S9). Thereby, a low-temperature working fluid is supplied to the isolation part 24a of the evaporator 24, and the temperature of the working fluid which flows through the part near the exit of the evaporator 24 can be lowered. The opening degree of the control valve 35 is, for example, fully open. By fully opening the control valve 35, the situation in which the working fluid may be excessively heated can be quickly removed. That is, the reliability of the Rankine cycle device 18 can be increased. However, it is not essential to fully open the control valve 35. For example, when the set upper limit temperature is sufficiently low, the opening degree of the control valve 35 may be increased stepwise.

  When the low-temperature working fluid is supplied to the evaporator 24 through the cooling passage 33, the amount of the working fluid that bypasses most of the evaporator 24 and reaches the outlet of the evaporator 24 increases. As a result, the temperature Th of the working fluid at the outlet of the evaporator 24 may be too low. When the temperature Th of the working fluid at the outlet of the evaporator 24 is too low, the theoretical recovery power of the expander 21 is lowered. Therefore, the temperature Th of the working fluid is detected by the temperature sensor 39, and the opening degree of the control valve 35 is changed based on the detection result (steps S10 to S14). Specifically, the opening degree of the control valve 35 is gradually reduced while checking the temperature Th detected by the temperature sensor 39 (step S13).

  When the processing of Step S10 to Step S14 is repeated, the opening degree of the control valve 35 is decreased stepwise, and accordingly, the flow rate of the working fluid in the cooling passage 33 is decreased stepwise. However, if the temperature sensor 39 detects a temperature Th higher than the upper limit in step S11, the process of reducing the opening of the control valve 35 is stopped, and the process returns to step S3.

  After the temperature Th detected by the temperature sensor 39 is between the upper limit and the lower limit and the control valve 35 is completely closed, the control returns to normal control. As described above, by continuously monitoring the temperature Th of the working fluid at the outlet of the evaporator 24 by the temperature sensor 39, it is possible to prevent the working fluid from being excessively heated in the evaporator 24.

  Hereinafter, other embodiments of the CHP system will be described. Elements common to the CHP system 100 shown in FIG. 1 and the following embodiments are assigned the same reference numerals, and descriptions thereof are omitted. That is, the description regarding each embodiment can be applied to other embodiments as long as there is no technical contradiction.

(Second Embodiment)
As shown in FIG. 4, in the Rankine cycle device 18B of the CHP system 200 of the present embodiment, the operation fluid flowing through the evaporator 24 by heat exchange between the working fluid flowing through the evaporator 24 and the working fluid flowing through the cooling passage 33. The fluid is cooled.

  The cooling path 33 includes an upstream portion 33a, a heat exchange portion 33c, and a downstream portion 33b. The upstream portion 33a has one end connected to the main circuit 20 at the branch position K1 between the outlet of the pump 23 and the inlet of the evaporator 24, and the other end connected to the heat exchange unit 33c. The downstream portion 33b has one end connected to the heat exchanging portion 33c and the other end connected to the main circuit 20 at a joining position K2 between the outlet of the expander 21 and the inlet of the condenser 22. The heat exchanging unit 33 c indirectly cools the working fluid flowing through the evaporator 24 by exchanging heat between the working fluid discharged from the pump 23 and the working fluid flowing through the evaporator 24. According to the first embodiment, the low temperature working fluid is mixed with the high temperature working fluid. On the other hand, in this embodiment, heat only moves in the heat exchanging portion 33c. Therefore, as compared with the method of the first embodiment, there is a possibility that the control of the Rankine cycle device 18B is likely to shift to the steady control after the cooling using the working fluid discharged from the pump 23 is started.

  A control valve 35 is disposed in the cooling path 33. Specifically, the control valve 35 is disposed in the upstream portion 33a. This arrangement is advantageous in reducing the amount of working fluid that remains in the cooling passage 33 when the control valve 35 is closed. However, the control valve 35 may be disposed in the downstream portion 33b.

  As shown in FIG. 5, also in the present embodiment, the evaporator 24 has a separating portion 24 b located outside the combustion chamber 12. The heat exchanging portion 33 c of the cooling path 33 is also located outside the combustion chamber 12. Thereby, it can avoid that the working fluid in the cooling path 33 is directly heated by the combustion gas G. The isolation part 24 b of the evaporator 24 is in contact with the heat exchange part 33 c of the cooling path 33. The isolation part 24 b is included in the downstream part 24 t of the evaporator 24. The separator 24b communicates with the heat transfer tube 28 at the most downstream stage of the evaporator 24 so that the working fluid cooled by the separator 24b flows into the heat transfer tube 28 at the most downstream stage of the evaporator 24. ing. Since the isolation part 24b is formed at such a position, it is possible to effectively prevent the working fluid from being heated excessively.

  The structure of the heat exchange part 33c of the cooling path 33 and the isolation part 24b of the evaporator 24 is not particularly limited. The heat exchange part 33c and the isolation part 24b may form a known heat exchanger structure such as a plate heat exchanger or a double tube heat exchanger. Moreover, the heat exchange part 33c and the isolation part 24b may have the structure shown in FIG. In the example of FIG. 6, the heat exchanging part 33c is a pipe wound in a spiral shape around the isolation part 24b. The isolation | separation part 24b is formed by piping which has an internal diameter larger than the heat exchange part 33c, for example.

  As shown in FIG. 4, in the present embodiment, the cooling path 33 joins the main circuit 20 between the outlet of the expander 21 and the inlet of the condenser 22. The pressure at the branch position K1 is high, and the pressure at the merge position K2 is low. That is, when the cooling path 33 is connected to the main circuit 20 between the outlet of the expander 21 and the inlet of the condenser 22, the working fluid flows smoothly into the cooling path 33 by opening the control valve 35.

  Specifically, the cooling path 33 joins the main circuit 20 between the outlet of the expander 21 and the inlet of the reheater 25 (joining position K2). The cooling path 33 may join the main circuit 20 between the outlet of the reheater 25 and the inlet of the condenser 22 (joining position k2). According to the former, heat can be transmitted through the reheater 25 from the working fluid heated in the heat exchanging portion 33c to the working fluid on the high pressure side of the Rankine cycle. According to the latter, since the amount of heat exchange in the reheater 25 is reduced, a lower temperature working fluid can be supplied to the evaporator 24. The latter is advantageous from the viewpoint of suppressing pressure loss. Regardless of the merging position, the cooling passage 33 can provide an effect of cooling the working fluid flowing through the evaporator 24.

  Also in the Rankine cycle device 18B, control for preventing the working fluid flowing through the evaporator 24 from being excessively heated can be executed according to the flowchart described with reference to FIG. That is, the control valve 35 is opened and closed based on the temperature Th detected by the temperature sensor 39. Alternatively, the opening degree of the control valve 35 is adjusted based on the temperature Th detected by the temperature sensor 39.

  The pressure at the branch position K1 is high, and the pressure at the merge position K2 (or k2) is low. That is, the pressure difference between the branch position K1 and the merge position K2 (or k2) is large. In this case, when the control valve 35 is fully opened, the working fluid preferentially flows through the cooling path 33 with a small pressure loss, and the amount of working fluid supplied to the inlet of the evaporator 24 may be greatly reduced. As a result, there is a concern that the working fluid is excessively heated upstream of the isolation part 24b. Therefore, it is desirable to appropriately adjust the opening degree of the control valve 35 so that a sufficient amount of working fluid is supplied to the inlet of the evaporator 24.

  Of course, an open / close valve may be used as the control valve 35. In this case, a pressure reducing unit such as a capillary tube may be provided in the cooling path 33 on the downstream side of the control valve 35. Furthermore, a pipe having a smaller inner diameter than the pipe of the main circuit 20 may be used as the pipe of the cooling path 33. According to such a configuration, the flow resistance of the cooling passage 33 is appropriately increased, so that the flow rate of the working fluid in the cooling passage 33 can be appropriately limited.

(Third embodiment)
As shown in FIG. 7, in the Rankine cycle device 18C of the CHP system 300 of this embodiment, the operation fluid flowing through the evaporator 24 is exchanged by the heat exchange between the working fluid flowing through the evaporator 24 and the working fluid flowing through the cooling passage 33. The fluid is cooled. In this regard, the present embodiment is the same as the second embodiment. However, in the present embodiment, the cooling path 33 joins the main circuit 20 between the outlet of the pump 23 and the inlet of the evaporator 24. In other words, the downstream portion 33b of the cooling path 33 has one end connected to the heat exchanging portion 33c and the other end connected to the main circuit 20 at the junction K3 between the outlet of the pump 23 and the inlet of the evaporator 24. And have. According to such a configuration, the flow rate of the working fluid in the evaporator 24 does not change before and after the control valve 35 is opened. Specifically, the entire amount of working fluid passes through the inlet of the evaporator 24. Therefore, a phenomenon in which the working fluid is excessively heated on the upstream side from the isolation part 24b due to a decrease in the flow rate of the working fluid cannot occur essentially.

  Specifically, the cooling path 33 joins the main circuit 20 between the outlet of the pump 23 and the inlet of the reheater 25 (joining position K3). The cooling path 33 may join the main circuit 20 between the outlet of the reheater 25 and the inlet of the evaporator 24 (joining position k3). Regardless of the merging position, the cooling passage 33 can provide an effect of cooling the working fluid flowing through the evaporator 24.

  The Rankine cycle device 18C includes a second control valve 40 in addition to the control valve 35 (hereinafter referred to as the first control valve 35). The second control valve 40 is provided in the main circuit 20 between the branch position K1 and the merge position K3 (or k3), and controls the flow of the working fluid in the main circuit 20. Similar to the first control valve 35, the second control valve 40 may be a valve capable of adjusting the flow rate of the working fluid by changing the opening degree, or may be an on-off valve. A combination of a pressure reducing component such as a capillary tube and an on-off valve may be used as the second control valve 40.

  In the present embodiment, the branch position K1 and the merge position K3 are positions on the high pressure side of the Rankine cycle. There is no significant difference between the pressure at the branch position K1 and the pressure at the merge position K3 (or k3). Therefore, there is a possibility that a sufficient amount of working fluid cannot be flowed to the cooling path 33 just by opening the first control valve 35. On the other hand, when the second control valve 40 is provided between the branching position K1 and the merging position K3, the first control valve 35 and the second control valve 40 are used, so that the cooling path 33 is appropriate. An amount of working fluid can be directed.

  In addition, when the cooling path 33 joins the main circuit 20 between the outlet of the pump 23 and the inlet of the reheater 25, the working fluid flows through the cooling path 33 and then near the inlet of the reheater 25. Returned to That is, the flow rate of the working fluid in the reheater 25 and the evaporator 24 does not depend on the flow rate of the working fluid in the cooling path 33. Therefore, an on-off valve can be suitably used as the first control valve 35 and the second control valve 40. If the first control valve 35 is opened and the second control valve 40 is closed, the entire amount of the working fluid discharged from the pump 23 is guided to the cooling path 33. In this case, the maximum cooling capacity is exhibited in the cooling part 33c. Despite the use of an indirect cooling method, it is possible to expect cooling with good response.

  On the other hand, when the cooling path 33 joins the main circuit 20 between the outlet of the reheater 25 and the inlet of the evaporator 24, the working fluid heated in the heat exchange part 33 c of the cooling path 33 is reheated. 25 is bypassed and supplied to the evaporator 24. Therefore, it is possible to suppress the heat given to the working fluid in the heat exchange part 33c from being released to the surroundings. This means efficient recovery of thermal energy and contributes to improvement in utilization efficiency of thermal energy generated by the combustor 14.

  As described above, the cooling path 33 can be joined to the main circuit 20 at an arbitrary joining position. The joining position is not particularly limited, and each joining position has an advantage. It is desirable to select the merging position according to the effect to be emphasized.

  Next, control executed by the control device 50 of the Rankine cycle device 18C will be described with reference to the flowchart of FIG. The processing of step ST1 to step ST14 in the flowchart of FIG. 8 corresponds to the processing of step S1 to step S14 of the flowchart of FIG. Therefore, only the difference between the control in this embodiment and the control described in the first embodiment will be described below.

  By increasing the circulation amount of the working fluid in step ST6, the increase in the temperature of the working fluid supplied to the inlet of the evaporator 24 can be offset by the increase in the flow rate of the working fluid when the first control valve 35 is opened. As a result, it is possible to prevent the working fluid from being heated excessively on the upstream side of the isolation part 24b.

  After adjusting the rotational speed fp of the pump 23 and the rotational speed fe of the expander 21 in steps ST5 to ST8, the first control valve 35 is opened and the second control valve 40 is closed in step ST9. Thereby, a low-temperature working fluid is supplied to the heat exchange part 33c, and the temperature of the working fluid which flows through the isolation | separation part 24b of the evaporator 24 can be lowered | hung. The opening degree of the first control valve 35 is, for example, fully open. The opening degree of the second control valve 40 is, for example, fully closed. As a result, the situation in which the working fluid may be excessively heated can be quickly removed. That is, the reliability of the Rankine cycle device 18C can be increased. However, it is not essential to fully open the first control valve 35 and fully close the second control valve 40. For example, when the set upper limit temperature is sufficiently low, the opening degree of the first control valve 35 may be increased stepwise and the opening degree of the second control valve 40 may be reduced stepwise. In this way, a sufficient amount of working fluid can be supplied to the cooling passage 33.

  In steps ST10 to ST14, the temperature Th of the working fluid is detected by the temperature sensor 39, and the opening degree of the first control valve 35 and the opening degree of the second control valve 40 are changed based on the detection result. Specifically, while confirming the temperature Th detected by the temperature sensor 39, the opening degree of the first control valve 35 is decreased stepwise and the opening degree of the second control valve 40 is increased stepwise (step ST13). .

  When the processing of step ST10 to step ST14 is repeated, the opening degree of the first control valve 35 decreases stepwise and the opening degree of the second control valve 40 increases stepwise. However, in step ST11, when the temperature Th higher than the upper limit is detected by the temperature sensor 39, the process of reducing the opening degree of the first control valve 35 and the process of increasing the opening degree of the second control valve 40 are stopped. Return to step ST3.

  After the temperature Th detected by the temperature sensor 39 is between the upper limit and the lower limit and the first control valve 35 is closed, the control returns to normal control. As described above, by continuously monitoring the temperature Th of the working fluid at the outlet of the evaporator 24 by the temperature sensor 39, it is possible to prevent the working fluid from being excessively heated in the evaporator 24.

(Other)
In the first to third embodiments, the reheater 25 may be omitted. In the second and third embodiments, the downstream end of the cooling path 33 may be connected to the reheater 25. The thermal fluid for evaporating the working fluid in the evaporator 24 is not limited to the combustion gas G generated in the combustor 14. For example, factory exhaust gas, gas heated by natural energy such as sunlight, and the like can be used as the thermal fluid. In some cases, the thermal fluid is a liquid. The second control valve 40 described in the third embodiment may be provided in the main circuit 20 of the Rankine cycle device 18B of the second embodiment. If the second control valve 40 is provided in the main circuit 20 between the branch position K1 and the inlet of the evaporator 24, the flow rate of the working fluid in the cooling passage 33 can be adjusted more accurately.

  The technology disclosed in this specification can be suitably used not only for a system that generates only electric power but also for a cogeneration system such as a CHP system. The technology disclosed in this specification is particularly suitable for a system in which power demand changes frequently.

18, 18B, 18C Rankine cycle device 20 Main circuit 21 Expander 22 Condenser 23 Pump 24 Evaporator 24a, 24b Separation unit 25 Reheater 26 Generator 27 Fin 28 Heat transfer tube 29 Bend tube 30 Heat medium circuit 31 Pump 32 Heat dissipation 33 Cooling path 35 Control valve (first control valve)
38 Pressure sensor 39 Temperature sensor 40 Second control valve 50 Controller 100, 200, 300 CHP system

Claims (11)

A main circuit formed by having an evaporator, an expander, a condenser and a pump, and these components are connected in a ring in this order;
A cooling passage configured to branch from the main circuit between the pump and the evaporator and to cool the working fluid flowing through the evaporator with the working fluid discharged from the pump;
A control valve provided in the cooling path and controlling the flow of the working fluid in the cooling path;
A Rankine cycle device.   The cooling path is connected to the evaporator so as to lower the temperature of the working fluid flowing through the evaporator by mixing the working fluid discharged from the pump and the working fluid flowing through the evaporator. The Rankine cycle device according to claim 1. The evaporator has an upstream portion relatively close to the inlet and a downstream portion relatively close to the outlet, with reference to an intermediate point of the flow path from the inlet to the outlet of the evaporator,
The Rankine cycle apparatus according to claim 2, wherein the cooling path is connected to the downstream portion. The evaporator is disposed in a flow path of a thermal fluid for heating the working fluid, and the flow path of the thermal fluid so that contact with the thermal fluid is prevented from being in contact with the thermal fluid. Having an isolator located in a location isolated from
The Rankine cycle apparatus according to claim 2 or 3, wherein the cooling path is connected to the isolation part.   The cooling path includes a heat exchange unit that indirectly cools the working fluid flowing through the evaporator by exchanging heat between the working fluid discharged from the pump and the working fluid flowing through the evaporator. The Rankine cycle apparatus according to claim 1.   The Rankine cycle apparatus according to claim 5, wherein the cooling path joins the main circuit between the expander and the condenser.   The Rankine cycle apparatus according to claim 5, wherein the cooling path joins the main circuit between the pump and the evaporator.   And a reheater for exchanging heat between the working fluid flowing through the main circuit between the pump and the evaporator and the working fluid flowing through the main circuit between the expander and the condenser. Furthermore, the Rankine cycle apparatus according to any one of claims 1 to 7. And a reheater for exchanging heat between the working fluid flowing through the main circuit between the pump and the evaporator and the working fluid flowing through the main circuit between the expander and the condenser. ,
The cooling path includes a heat exchanging section that indirectly cools the working fluid flowing through the evaporator by exchanging heat between the working fluid discharged from the pump and the working fluid flowing through the evaporator. And
The cooling path joins the main circuit between (a) the expander and the reheater, and (b) joins the main circuit between the reheater and the condenser. (C) joining the main circuit between the pump and the reheater, or (d) joining the main circuit between the reheater and the evaporator. The Rankine cycle apparatus according to claim 1. The cooling path branches off from the main circuit at a branch position between the pump and the evaporator, and joins the main circuit at an arbitrary joining position,
6. The Rankine cycle device according to claim 5, further comprising a second control valve that is provided in the main circuit between the branch position and the merging position and controls a flow of the working fluid in the main circuit. Rankine cycle equipment. Rankine cycle device according to any one of claims 1 to 10,
A heat medium circuit through which a heat medium as a low-temperature heat source for cooling the working fluid flows in the condenser of the Rankine cycle device;
A combined heat and power system.

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