Power generation system for ship

Abstract

In a power generation system (1) for a ship, a control means (30) operates a circulation pump (22) if, while the circulation pump (22) is in a stoppage, a load factor acquired by a load factor information acquisition means (32) is equal to or greater than a predetermined value or a temperature detected by a second temperature detection means (46) is equal to or greater than a predetermined value.

Description

Marine power generation system

[0001] The present invention relates to a marine power generation system. The present application claims priority based on Japanese Patent Application No. 2025-043324 filed in Japan on March 18, 2025, the content of which is incorporated herein by reference.

[0002] Conventionally, marine power generation systems using an organic Rankine cycle have been known. For example, Patent Document 1 discloses a first exhaust heat recoverer 1 (exhaust gas economizer) that recovers heat from exhaust gas discharged from a marine diesel engine (main propulsion engine), a second exhaust heat recoverer 5 that recovers heat from an air cooler 3 of a supercharger provided in the diesel engine, a heat medium passage 7 through which a heat medium that receives exhaust heat from these exhaust heat recoverers 1 and 5 circulates, and an organic fluid passage 9 that receives heat from the heat medium in the heat medium passage 7. This exhaust heat recovery power generation装置 10 evaporates an organic fluid by heat input from the heat medium flowing through the heat medium passage 7 in a single evaporator 60 provided in the organic fluid passage 9, and rotationally drives a turbine 62 with the organic fluid gas, thereby causing a generator 68 to generate power.

[0003] Further, Patent Document 2 discloses a power generation device in which an evaporator 11 and a superheater 12 are provided in order from the discharge side of a working medium pump 15 in a circulation passage 10 through which a working medium having a lower boiling point than water circulates. This power generation device causes a heating medium such as steam or hot water to flow through the superheater 12 and the evaporator 11 in this order, superheats the working medium while evaporating it, and rotationally drives a screw expander 13 with the working medium gas, thereby causing a generator 18 to generate power. The power generation device further includes pump control means for controlling the rotation speed of the working medium pump 15 so that the degree of superheat at the outlet side of the superheater 12 reaches a predetermined target value, and when the temperature of the working medium at the outlet side of the evaporator 11 is lower than the saturation temperature, performs control to reduce the circulation flow rate of the working medium by increasing the predetermined target value for the degree of superheat.

[0004] Japanese Unexamined Patent Application Publication No. 2011-149332, Japanese Unexamined Patent Application Publication No. 2014-47632

[0005] The system described in Patent Document 1 is configured to absorb the waste heat contained in compressed air and exhaust gas into a heat transfer medium, and therefore requires at least three heat exchangers (1, 5, 60) and a heat transfer medium circulation pump for heat recovery. In addition, multiple valves are required to adjust the flow rate of compressed air and exhaust gas flowing into the heat exchangers (1, 5), which tends to result in high equipment costs, including installation work. Therefore, it is conceivable to use a system like the one described in Patent Document 2, which uses two heat exchangers (11, 12) for heat recovery, with compressed air and exhaust gas flowing through each of them, and without adjusting the flow rate of these heat source fluids. A shipboard power generation system configured in this way can be shut down by operating it in a way that prevents the circulation of the working fluid.

[0006] Incidentally, if the working fluid is not circulating through the circulation channel and the temperature of the heat source fluid rises, the working fluid may undergo thermal decomposition. On the other hand, if the working fluid is constantly circulated, power consumption increases, and operating costs rise.

[0007] Therefore, the present invention aims to provide a shipboard power generation system that suppresses thermal decomposition of the working fluid while suppressing an increase in power consumption for circulating the working fluid.

[0008] The present invention relates to a shipboard power generation system comprising: a circulation circuit for circulating a working medium having a lower boiling point than water; a circulation pump for circulating the working medium within the circulation circuit; a first heater for heating the working medium from the circulation pump using supercharged air from a supercharger attached to an internal combustion engine as a heat source fluid; a second heater for heating the working medium after it has been heated in the first heater using exhaust gas from the internal combustion engine as a heat source fluid; an expander that is rotated by the expansion energy of the working medium after it has been heated in the second heater; a cooler for cooling the working medium after it has passed through the expander with a cooling fluid; and a device connected to the expander, which expands The system comprises a generator driven by the rotation of the machine, a first flow rate adjustment means for adjusting the flow rate of the working medium supplied from the circulation pump, a control means for controlling the operation of the power generation system, a load factor information acquisition means provided in the control means for acquiring the load factor of the internal combustion engine, and a temperature detection means for detecting the temperature of the supercharged air from the supercharger. The control means activates the circulation pump when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means exceeds a predetermined value, or when the temperature detected by the temperature detection means exceeds a predetermined value.

[0009] The present invention provides a shipboard power generation system that suppresses thermal decomposition of the working fluid while reducing the power consumption required to circulate the working fluid.

[0010] This figure shows a schematic diagram of a shipboard power generation system according to an embodiment of the present invention.

[0011] Figure 1 is a schematic diagram of a shipboard power generation system 1 according to an embodiment of the present invention. The shipboard power generation system 1 of this embodiment is a system that generates electricity using the waste heat of a ship 100 by an organic Rankine cycle (ORC), and utilizes the supercharged air and exhaust gas generated by the operation of the internal combustion engine 60 as heat source fluids. An ORC power generation system is also called a binary power generation system because it generates electricity using two thermal cycles: a heat source fluid system and a working fluid system.

[0012] 1. Configuration of the ship's main engine and auxiliary engines The ship 100 in this embodiment is, for example, an LNG (liquefied natural gas) carrier and comprises an internal combustion engine 60 that provides propulsion to the hull, a fuel supply means 62 that supplies fuel F1 and F2 to the internal combustion engine 60, a supercharger 64 that supplies supercharger air A2 to the internal combustion engine 60, and an exhaust turbine 66 connected to the supercharger 64 and rotated by exhaust gas E1 from the internal combustion engine 60.

[0013] The internal combustion engine 60 is a two-stroke diesel engine called the main engine. In addition to heavy oil, the internal combustion engine 60 can also use a portion of the LNG cargo as fuel. The fuel supply means 62 consists of a first fuel supply means 62A having an LNG tank and a vaporizer, and a second fuel supply means 62B having a heavy oil tank and a preheater. The first fuel supply means 62A is connected to the internal combustion engine 60 via a first fuel line LF1. The second fuel supply means 62B is connected to the internal combustion engine 60 via a second fuel line LF2. In the figure, LNG is indicated by the symbol F1 and heavy oil by the symbol F2.

[0014] The internal combustion engine 60 switches between three combustion modes depending on the navigation conditions of the ship 100. Specifically, the first combustion mode is an LNG-only combustion mode in which only LNG, which is the gas fuel F1, is supplied. The second combustion mode is an LNG-heavy oil mixed combustion mode in which heavy oil, which is the oil fuel F2, and LNG, which is the gas fuel F1, are supplied simultaneously. The third combustion mode is a heavy oil-only combustion mode in which heavy oil, which is the oil fuel F2, is supplied alone.

[0015] The supercharger 64 is a device that, in the operation of the exhaust turbine 66, draws in air A1 from outside the ship and compresses this air A1 to generate supercharged air A2. The intake section of the supercharger 64 is connected to an air filter (not shown) via an intake line LA3. The discharge section of the supercharger 64 is connected to the inlet of the high-temperature side passage of the intercooler 70 via a first supply line LA1.

[0016] The intercooler 70 is a heat exchanger that removes the heat of compression contained in the supercharged air A2 by heat exchange with the cooling water W1. The outlet of the high-temperature side passage of the intercooler 70 is connected to the inlet of the venturi mixer that constitutes the internal combustion engine 60 via the second air supply line LA2. In addition, the low-temperature side passage of the intercooler 70 is connected to the first cooling water line LW1, which allows seawater pumped from the sea area during navigation, or fresh water circulated in the ship's central cooling system, to flow in and out as cooling water W1.

[0017] The Venturi mixer is a device that uses supercharged air A2 as the driving fluid and utilizes the Venturi effect of the airflow to draw in fuels F1 and F2 and generate a fuel-air mixture. The generated mixture is supplied to the combustion chamber of the internal combustion engine 60. The exhaust chamber, which is part of the internal combustion engine 60, is a device that utilizes the kinetic energy of the combustion gases continuously flowing out of the combustion chamber to improve the filling efficiency of the fuel-air mixture. While the internal combustion engine 60 is in operation, the combustion gases that flow into the exhaust chamber expand within the chamber and are discharged as exhaust gas E1. The outlet of the exhaust chamber is connected to the inlet of the exhaust turbine 66 via the first exhaust gas line LE1.

[0018] The exhaust turbine 66 is a device that recovers a portion of the thermal energy of the exhaust gas E1 discharged from the exhaust chamber and drives the supercharger 64. Inside the exhaust turbine 66, the expansion energy of the exhaust gas E1 is converted into kinetic energy, which drives the rotation shaft of the impeller. The rotation shaft of the impeller drives the rotation shaft of the supercharger 64, which is connected by a coupling or the like. The outlet of the exhaust turbine 66 is connected to the chimney of the ship 100 via the second exhaust gas line LE2, and the exhaust gas E2, after heat recovery in the second heater 12 (described later), is released overboard from the chimney.

[0019] The ship's power generation system 1 of this embodiment may also be equipped with an exhaust gas economizer. The exhaust gas economizer is a type of steam generator that utilizes the thermal energy of the exhaust gas E2 that has passed through the exhaust turbine 66, and together with a steam-water separation drum (not shown), it constitutes an exhaust gas boiler. When an exhaust gas economizer is provided, the exhaust gas economizer has a large number of steam pipes (heat transfer pipes) arranged inside the shell through which the exhaust gas E2 flows. One side of each steam pipe is connected to a feedwater header for distributing feedwater, and the other side of each steam pipe is connected to a steam header for collecting steam. A feedwater line is connected to the feedwater header to guide the stored water inside the steam-water separation drum as feedwater. On the other hand, a steam line is connected to the steam header to return the generated steam back to the steam-water separation drum. The steam separated in the steam-water separation drum is used for preheating heavy oil, etc. The shell outlet of the exhaust gas economizer is connected to the chimney of the ship 100 via an exhaust gas line, and the exhaust gas after heat recovery is released overboard through the chimney.

[0020] 2. Configuration of the Marine Power Generation System The marine power generation system 1 of this embodiment includes a circulation pump 22, a first heater 10, a second heater 12, an expander 16, and a cooler 20. These devices are connected in a ring shape by a circulation circuit LC of the working medium R in the order described above. Since this circulation circuit LC is laid over a wide area in the horizontal and vertical directions within the ship, it can also be called a transport pipeline for the working medium R. The marine power generation system 1 also includes control means 30 for controlling the operation of the system.

[0021] A polymeric organic compound with a lower boiling point than water is used as the working fluid R circulating in the circulation circuit LC. The working fluid R is a fluorocarbon-based medium such as HFC-245fa (chemical name: 1,1,1,3,3-pentafluoropropane, boiling point at 1 atm: 15.3°C). Alternatively, non-fluorocarbon-based media such as isopentane (boiling point at 1 atm: 27.8°C) or pentane (boiling point at 1 atm: 36.1°C) may be used. In addition, a lubricating oil with a higher boiling point than the polymeric organic compound may be mixed with the working fluid R to reduce friction and cool the expander 16.

[0022] The circulation pump 22 is a device for circulating the working medium R containing lubricating oil within the circulation circuit LC, and is driven, for example, by an inverter device 40. In this embodiment, the rotational speed of the drive motor of the circulation pump 22 is adjusted using the variable voltage variable frequency control function of the inverter device 40.

[0023] The first heater 10 uses the working medium R (medium liquid R) delivered from the circulation pump 22. Ｌ This is a heat exchanger that heats the working medium R. The high-temperature side flow path of the first heater 10 is connected in the middle of the first air supply line LA1, and uses supercharged air A2 from the supercharger 64 as a heat source fluid to heat the working medium R flowing through the low-temperature side flow path. The first heater 10 operates as an evaporator by adjusting the flow rate of the working medium R supplied from the circulation pump 22. That is, the working medium liquid that flows in from the inlet of the low-temperature side flow path of the first heater 10 becomes saturated steam (moist steam) or superheated steam due to the heat input from the supercharged air A2.

[0024] The second heater 12 uses the working medium R (medium gas R) after it has been heated by the first heater 10. Ｇ This is a heat exchanger that heats the steam. The high-temperature side flow path of the second heater 12 is connected in the middle of the second exhaust gas line LE2, and uses the exhaust gas E2 from the exhaust turbine 66 as a heat source fluid to heat the working medium R flowing through the low-temperature side flow path. The second heater 12 operates as a superheater by adjusting the flow rate of the working medium R supplied from the circulation pump 22. That is, saturated steam or superheated steam flowing in from the inlet of the low-temperature side flow path of the second heater 12 is further superheated by the heat input from the exhaust gas E2, and becomes even hotter superheated steam by the time it flows out from the outlet.

[0025] The expander 16 is in a superheated state. Ｇ This device converts the expansion energy of a screw rotor into kinetic energy and drives a rotating shaft. The main body of the expander 16 has, for example, a twin-screw type expansion mechanism. The rotating shaft of the screw rotor drives the rotating shaft of the generator 18, which is connected by a coupling or the like. The expander 16 may also have other expansion mechanisms such as a turbine, and may be either oil-lubricated or oil-free.

[0026] The cooler 20 is cooled by the expander 16 and the working medium R (medium gas R) is increased in volume. Ｇ This is a heat exchanger that condenses the working fluid. The high-temperature side passage of the cooler 20 is connected in the middle of the circulation circuit LC, and the working fluid R is cooled using cooling water W2 as the cooling fluid. The low-temperature side passage of the cooler 20 is connected to a second cooling water line LW2 for inflow and out of the cooling water W2, which is seawater pumped up from the sea area during navigation or fresh water circulated in the ship's central cooling equipment. A cooling water pump may be provided in the second cooling water line LW2 as needed.

[0027] The generator 18 is connected to the expander 16 and is driven by the expansion of the working medium R in the expansion space, which rotates the screw rotor. The generator 18 in this embodiment is, for example, a permanent magnet synchronous generator. This permanent magnet synchronous generator has a rotating shaft connected to one side of the screw rotor, and generates electricity by the rotation of this rotating shaft in conjunction with the rotation of the screw rotor.

[0028] A first temperature detection means 44 is provided near the outlet of the low-temperature side flow path of the first heater 10. The first temperature detection means 44 is a sensor that detects the temperature of the working medium R immediately after it flows out of the first heater 10. Each detection signal from the first temperature detection means 44 is input to a control means 30, which will be described later.

[0029] The control means 30 includes a circulation flow control unit 31 and a fuel type information acquisition means 33. The circulation flow control unit 31 controls the rotational speed of the circulation pump 22 by an inverter device 40 so that the first heater 10 operates as an evaporator and the second heater 12 operates as a superheater. The load factor information acquisition means 32 acquires information regarding the load factor of the internal combustion engine 60. The fuel type information acquisition means 33 acquires information regarding the fuel type supplied to the internal combustion engine 60. Specifically, the fuel type information acquisition means 33 identifies the fuel type using combustion mode information of the internal combustion engine 60 (LNG-only combustion mode, LNG / heavy oil mixed combustion mode, heavy oil-only combustion mode).

[0030] Here, the mechanism of heat recovery and power generation will be explained. The working fluid R is pressurized by the operation of the circulation pump 22 and flows through the circulation circuit LC in the direction of the arrow. In the first heater 10 and the second heater 12, the working fluid R is heated by heat recovery from the heat source fluids (supercharged air A2, exhaust gas E2) described above and becomes superheated steam. The working fluid R becomes high temperature and high pressure superheated steam. Ｇ This rotates the screw rotor of the expander 16 to drive the generator 18. The working medium R becomes low-temperature, low-pressure expanded vapor after passing through the screw rotor. Ｇ The working medium R is cooled in the cooler 20 and becomes a condensate. Ｌ The working fluid R is then sent back to the first heater 10 and the second heater 12 by the circulation pump 22. In this way, the working fluid R repeatedly changes state while circulating through the circulation circuit LC, making it possible to convert thermal energy into electrical energy.

[0031] 3. Bypass switching control of the working medium and exhaust gas The ship power generation system 1 of this embodiment includes a first bypass path LB1 that bypasses the exhaust gas E2 to the second heater 12. The first bypass path LB1 is a bypass path that bypasses the exhaust gas E2.

[0032] The first bypass line LB1 branches off from the second exhaust gas line LE2 upstream of the second heater 12. A two-way valve V3, which constitutes a heating mode switching means, is provided downstream of this branching point and upstream of the second heater 12. The first bypass line LB1 merges with the second exhaust gas line LE2 downstream of the second heater 12. The first bypass line LB1 is provided with a two-way valve V4, which constitutes a heating mode switching means. Two-way valves V3 and V4 can be replaced with, for example, butterfly-type damper valves. Alternatively, a three-way valve may be provided at the branching point of the first bypass line LB1 instead of the two-way valves V3 and V4.

[0033] During power generation operation with the circulation pump 22 driven, the control means 30 opens the two-way valve V3 and closes the two-way valve V4. This allows the exhaust gas E2 to flow to the second heater 12 and heat the working medium R. On the other hand, during power generation standby with the circulation pump 22 stopped, the two-way valve V3 is closed and the two-way valve V4 is opened. This allows the exhaust gas E2 to flow to the first bypass path LB1 for the second heater 12, suppressing heat input to the working medium R.

[0034] 4. Operation while the circulation pump is stopped As mentioned above, when the circulation pump 22 is stopped, heat input to the working medium R is suppressed by circulating the exhaust gas E2 through the first bypass path LB1. However, when the internal combustion engine 60 is running, the supercharged air A2 circulates through the first heater 10, so the working medium R may be heated inside the first heater 10. If the temperature of the supercharged air A2 is high, the working medium R inside the first heater 10 may reach its thermal decomposition temperature. While the circulation pump 22 is stopped, the working medium R does not circulate through the circulation circuit LC, and therefore is not cooled by the cooler 20. For this reason, while the circulation pump 22 is stopped, the temperature of the working medium R inside the first heater 10 tends to rise.

[0035] The marine power generation system 1 includes a second temperature detection means 46 for detecting the temperature of the supercharged air A2 from the supercharger 64 in order to prevent the temperature of the working medium R from rising too high when the circulation pump 22 is stopped. The second temperature detection means 46 is provided in the first air supply line LA1. The second temperature detection means 46 can be a temperature sensor, similar to the first temperature detection means 44.

[0036] The control means 30 activates the circulation pump 22 when the load factor acquired by the load factor information acquisition means 32 exceeds a predetermined value, or when the temperature detected by the second temperature detection means 46 exceeds a predetermined value, while the circulation pump 22 is stopped. As a result, the working medium R circulates within the circulation circuit LC, preventing the temperature of the working medium R from rising too high. This suppresses the thermal decomposition of the working medium R while reducing the power consumption required to circulate the working medium R. This is because the circulation pump 22 operates only when necessary, not at all times. Furthermore, the temperature of the working medium R can also be monitored by the first temperature detection means 44. As a result, activating the circulation pump 22 allows confirmation that the temperature of the working medium R is maintained within an appropriate range.

[0037] The predetermined value of the temperature detected by the second temperature detection means 46 can be set, for example, based on the thermal decomposition temperature of the working medium R. For example, if the thermal decomposition temperature of the working medium R is 150°C, the predetermined value can be set to 145°C.

[0038] Furthermore, the control means may supply cooling water W2 to the cooler 20 as a cooling fluid when the circulation pump 22 is stopped and the load factor acquired by the load factor information acquisition means 32 exceeds a predetermined value, or when the temperature detected by the second temperature detection means 46 exceeds a predetermined value. The cooling water W2 to the cooler 20 can be supplied via the second cooling water line LW2.

[0039] By supplying cooling water W2 to the cooler 20, the working fluid R in the circulation circuit LC is cooled by the cooler 20. This forcibly cools the working fluid R, which has reached a higher temperature, and quickly cools it to the appropriate temperature, thereby avoiding the risk of thermal decomposition.

[0040] The circulation circuit LC is provided with a second bypass path LB2 that bypasses the expander 16. One end of the second bypass path LB2 is connected to the upstream side of the expander 16 in the circulation circuit LC, and the other end is connected to the downstream side. A two-way valve V5 is provided between the upstream end of the second bypass path LB2 and the expander 16. A two-way valve V6 is provided in the second bypass path LB2.

[0041] The control means 30 switches the flow path of the working medium R to the second bypass path LB2 when the load rate acquired by the load rate information acquisition means 32 reaches or exceeds a predetermined value, or when the temperature detected by the second temperature detection means 46 reaches or exceeds a predetermined value, while the circulation pump 22 is stopped. That is, the circulation pump 22 is activated, and the flow path is switched to the second bypass path LB2. In this way, while the generator 18 is generating power (during power generation operation), the working medium R is caused to flow through the circulation circuit LC, and while the working medium R is cooled without causing the generator 18 to generate power (during cooling operation), the working medium R is caused to flow through the second bypass path LB2. Specifically, during power generation operation, the two-way valve V5 is opened and the two-way valve V6 is closed. On the other hand, during cooling operation, the two-way valve V5 is closed and the two-way valve V6 is opened. This prevents ungasified working medium R from flowing into the expander 16 during cooling operation, and avoids damage to the expander 16.

[0042] Furthermore, when the circulation pump 22 is stopped, the exhaust gas E2 can be bypassed to the first bypass path LB1. The two-way valve V3 is closed and the two-way valve V4 is opened. This prevents the exhaust gas E2 from flowing into the second heater 12, and suppresses a temperature rise of the working medium R.

[0043] According to the present embodiment, the temperature of the supercharged air A2 or the load factor of the internal combustion engine 60 is monitored, and the circulation of the working medium R during power generation standby is controlled. Thereby, when the load factor of the internal combustion engine 60 is low and the temperature of the supercharged air A2 is relatively low, the circulation pump 22 can be stopped to avoid unnecessary power consumption. On the other hand, when the load factor of the internal combustion engine 60 is high and the temperature of the supercharged air A2 is relatively high, thermal decomposition of the working medium R can be prevented while activating the circulation pump 22 to use the minimum necessary electric power.

[0044] The embodiments of the present invention have been described above. The present invention is not limited to the above-described embodiments, and various modifications, alterations, and combinations are possible.

[0045] (1) A circulating circuit for circulating a working medium having a lower boiling point than water; a circulating pump for circulating the working medium within the circulating circuit; a first heater for heating the working medium from the circulating pump using supercharged air from a supercharger attached to an internal combustion engine as a heat source fluid; a second heater for heating the working medium after it has been heated in the first heater using exhaust gas from the internal combustion engine as a heat source fluid; an expander rotated by the expansion energy of the working medium after it has been heated in the second heater; a cooler for cooling the working medium after it has passed through the expander with a cooling fluid; a generator connected to the expander and driven by the rotation of the expander; a first flow rate adjustment means for adjusting the flow rate of the working medium supplied from the circulating pump; a control means for controlling the operation of the power generation system; a load factor information acquisition means provided in the control means for acquiring the load factor of the internal combustion engine; and a temperature detection means for detecting the temperature of the supercharged air from the supercharger. The control means activates the circulation pump when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means exceeds a predetermined value, or when the temperature detected by the temperature detection means exceeds a predetermined value.

[0046] (2) The ship power generation system according to (1), wherein the control means supplies cooling fluid to the cooler when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means becomes equal to or greater than a predetermined value, or when the temperature detected by the temperature detection means becomes equal to or greater than a predetermined value.

[0047] (3) The ship power generation system according to (1) or (2), wherein the circulation circuit is provided with a second bypass path that bypasses the expander, and the control means flows the working medium into the second bypass path when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means becomes equal to or greater than a predetermined value, or when the temperature detected by the temperature detection means becomes equal to or greater than a predetermined value.

[0048] (4) A ship power generation system according to any one of (1) to (3), wherein the system is provided with a first bypass path through which exhaust gas from the internal combustion engine bypasses the second heater, and the control means directs the exhaust gas to the first bypass path when the circulation pump is stopped.

[0049] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The shipboard power generation system described in this disclosure can contribute to achieving Sustainable Development Goal 7, "Affordable and Clean Energy," and Goal 13, "Climate Action."

[0050] 1. Marine power generation system 10. First heater 11. Evaporator 12. Second heater 16. Expander 18. Generator 20. Cooler 22. Circulation pump 30. Control means 31. Circulation flow control unit 32. Load factor information acquisition means 33. Fuel type information acquisition means 44. First temperature detection means 46. Second temperature detection means 60. Internal combustion engine 60. Evaporator 62. Turbine 62. Fuel supply means 64. Supercharger 66. Exhaust turbine 68. Generator 100. Ship

Claims

1. A power generation system comprising: a circulation circuit for circulating a working medium having a lower boiling point than water; a circulation pump for circulating the working medium within the circulation circuit; a first heater for heating the working medium from the circulation pump using supercharged air from a supercharger attached to an internal combustion engine as a heat source fluid; a second heater for heating the working medium after it has been heated in the first heater using exhaust gas from the internal combustion engine as a heat source fluid; an expander rotated by the expansion energy of the working medium after it has been heated in the second heater; a cooler for cooling the working medium after it has passed through the expander with a cooling fluid; a generator connected to the expander and driven by the rotation of the expander; a first flow rate adjustment means for adjusting the flow rate of the working medium supplied from the circulation pump; a control means for controlling the operation of the power generation system; a load factor information acquisition means provided in the control means for acquiring the load factor of the internal combustion engine; and a temperature detection means for detecting the temperature of the supercharged air from the supercharger. The control means activates the circulation pump when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means exceeds a predetermined value, or when the temperature detected by the temperature detection means exceeds a predetermined value.

2. The ship power generation system according to claim 1, wherein the control means supplies cooling fluid to the cooler when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means exceeds a predetermined value, or when the temperature detected by the temperature detection means exceeds a predetermined value.

3. The ship's power generation system according to claim 1 or 2, wherein the circulation circuit is provided with a second bypass path that bypasses the expander, and the control means flows the working medium into the second bypass path when the circulation pump is stopped and the load factor acquired by the load factor information acquisition means becomes equal to or greater than a predetermined value, or when the temperature detected by the temperature detection means becomes equal to or greater than a predetermined value.

4. The ship power generation system according to claim 1 or 2, wherein a first bypass path is provided through which exhaust gas from the internal combustion engine bypasses the second heater, and the control means directs exhaust gas to the first bypass path when the circulation pump is stopped.

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