Ship power generation system

Abstract

To provide a marine power generation system that can effectively use energy generated in a ship.SOLUTION: A marine power generation system 1 is used in a ship S comprising an internal combustion engine 11, and an exhaust gas turbine type supercharger 12 for sending supercharged air A1 into the internal combustion engine 11, and comprises: an exhaust gas economizer 31 for generating steam S1 by using exhaust gas E1 from the internal combustion engine 11; and a binary power generator 40 for recovering thermal energy via a circulating working medium, and generating power on the basis of expansion of the working medium. The binary power generator 40 comprises a first evaporator 41A for heating the working medium R1 by exchanging heat between the supercharged air A1 from the supercharger 12 and the working medium R1, and a second evaporator 41B for heating the working medium R1 by exchanging heat between the exhaust gas E1 from the internal combustion engine 11 and the working medium R1. The exhaust gas E1 from the internal combustion engine 11 flows through an exhaust gas turbine that is a driving source for the supercharger 12, the exhaust gas economizer 31, and the second evaporator 41B in this order.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a ship power generation system.

Background Art

[0002] Conventionally, a ship power generation system is known. For example, Patent Document 1 discloses a ship power generation system having an air cooler that preheats feed water using air and a waste heat boiler that vaporizes water preheated using exhaust gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the ship power generation system of Patent Document 1, power generation can be performed by rotating a steam turbine with steam generated in a waste heat boiler. However, it cannot be said that the ship power generation system of Cited Document 1 sufficiently and effectively utilizes the energy generated in a ship.

[0005] An object of the present invention is to provide a ship power generation system capable of effectively utilizing the energy generated in a ship.

Means for Solving the Problems

[0006] The present invention is a ship power generation system (for example, ship power generation system 1) used for a ship including an internal combustion engine (for example, internal combustion engine 11) and an exhaust gas turbine type supercharger (for example, supercharger 12) that feeds supercharged air (for example, supercharged air A1) to the internal combustion engine, An exhaust gas economizer (e.g., exhaust gas economizer 31) that generates steam (e.g., steam S1) using exhaust gas (e.g., exhaust gas E1) from the internal combustion engine, wherein heat energy is recovered through a circulating working medium (for example, working medium R1), 、 The aforementioned ​A binary generator (e.g., binary generator 40) that generates electricity based on the expansion of the working medium. of The binary generator is equipped with supercharged air from the supercharger and The aforementioned Heat exchange with the working medium The aforementioned A first evaporator (e.g., first evaporator 41A) that heats the working medium, and exhaust gas from the internal combustion engine The aforementioned Heat exchange with the working medium The aforementioned The system includes a second evaporator (e.g., second evaporator 41B) for heating the working medium, and the exhaust gas from the internal combustion engine flows in the following order: exhaust turbine, which is the drive source for the supercharger; exhaust gas economizer; and the second evaporator. The heating of the working medium is performed in the order of heating in the first evaporator and then heating in the second evaporator. Regarding ship-mounted power generation systems.

[0007] Furthermore, the binary generator further includes a third evaporator (for example, a third evaporator 41C), and the third evaporator is connected to the steam generated in the exhaust gas economizer. The aforementioned Heat exchange with the working medium The aforementioned It is preferable to heat the working medium.

[0008] Furthermore, the internal combustion engine uses liquefied fuel gas as fuel. death , The aforementioned vessel is A boiler (e.g., boiler 32) that generates steam (e.g., steam S2) using boil-off gas of liquefied fuel gas as fuel. of The binary generator further comprises a third evaporator (for example, a third evaporator 41C), and the third evaporator is connected to the steam generated in the boiler and The aforementioned Heat exchange with the working medium The aforementioned It is preferable to heat the working medium.

[0009] Furthermore, the system preferably includes a steam expander generator (for example, a steam expander generator 50) that converts the expansion of steam into rotational force to generate electricity, and the steam expander generator generates electricity using the steam produced by the exhaust gas economizer.

[0010] Furthermore, the internal combustion engine uses liquefied fuel gas as fuel. death , The aforementioned vessel isA boiler (e.g., boiler 32) that generates steam (steam S2) using the boil-off gas of liquefied fuel gas as fuel Equipped with , a steam expander generator (e.g., steam expander generator 50) that converts the expansion of steam into rotational force to generate electricity of Furthermore, it is preferable that the steam expander generator generates electricity using the steam generated by the boiler.

[0011] Also, it is preferable to further include a steam binary generator (e.g., steam binary generator 60) that generates electricity using the steam (e.g., steam S4) after being used in the steam expander generator as a heat source fluid.

[0012] Also, the steam binary generator preferably has an evaporator (e.g., evaporator 61) that heats the working medium by heat exchange between the steam after being used in the steam expander generator and The aforementioned steam binary generator circulates a working medium (e.g., working medium R2). The aforementioned steam binary generator circulates

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a ship power generation system capable of effectively utilizing the energy generated in a ship.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram showing a ship power generation system according to a first embodiment of the present invention. [Figure 2] It is a schematic diagram showing a ship power generation system according to a second embodiment of the present invention.

Modes for Carrying Out the Invention

[0015] <First Embodiment> Hereinafter, a ship power generation system 1 according to an embodiment of the present invention will be described with reference to the drawings. In this specification, the "line" is a general term for lines such as flow paths, routes, and pipelines through which fluids can flow.

[0016] ​ FIG. 1 is a schematic diagram showing a ship S equipped with the ship power generation system 1 of the present embodiment. The ship power generation system 1 of the present embodiment is a power generation system 1 used for a ship S equipped with an internal combustion engine 11 and a supercharger 12. Here, the ship S equipped with the power generation system 1 of the present embodiment includes an internal combustion engine 11, a supercharger 12, an intercooler 13, a fuel tank 20, a high-pressure pump 21, a vaporizer 22, a compressor 25, and a generator 26.

[0017] The internal combustion engine 11 is, for example, a main engine for obtaining power for propelling the ship. The internal combustion engine 11 of the present embodiment is a well-known diesel engine in which cylinders are held in a main engine box (not shown), and pistons are fitted into the cylinders so as to be able to advance and retreat. The internal combustion engine 11 sucks supercharged air A1 (compressed air A1) sent from the air line LA1 into the cylinder, compresses it with a piston, injects fuel into the air in a high-pressure state, and causes explosion combustion to drive the piston to obtain rotational power. When the internal combustion engine 11 is operated, exhaust gas E1 is generated. The exhaust gas E1 is discharged through an exhaust gas line LE1 connected to the internal combustion engine 11.

[0018] The internal combustion engine 11 of the present embodiment uses liquefied fuel gas as fuel. The liquefied fuel gas is supplied from a fuel tank 20 described later through a fuel line LF1. As the liquefied fuel gas, for example, liquefied natural gas (LNG), liquefied petroleum gas (LPG), ammonia, or the like may be used. In the present embodiment, LNG is used.

[0019] The supercharger 12 is an exhaust turbine type turbocharger, and sends supercharged air A1 into the internal combustion engine 11. The supercharger 12 takes in air A1 by the rotational force of an exhaust turbine that rotates by the flow of exhaust gas E1 discharged from the internal combustion engine 11, and compresses the air A1. The compressed supercharged air A1 is sent into the internal combustion engine 11 through the air line LA1.

[0020] The intercooler 13 cools the supercharged air A1 supplied to the internal combustion engine 11. The intercooler may be water-cooled or air-cooled. In the case of water cooling, seawater may be used as the coolant. In this embodiment, the supercharged air A1 supplied from the supercharger 12 is cooled in the first evaporator 41A (described later) and then supplied to the intercooler 13 for further cooling.

[0021] The fuel tank 20 is a tank that stores liquefied fuel gas to be supplied to the internal combustion engine 11. The liquefied fuel gas is stored in the fuel tank 20 in a liquid state. In this embodiment, LNG is stored in the fuel tank 20 as the liquefied fuel gas.

[0022] The high-pressure pump 21 pressurizes the LNG stored in the fuel tank 20 while it is still in liquid form and supplies it to the vaporizer 22.

[0023] The vaporizer 22 vaporizes the LNG supplied from the fuel tank 20. The vaporizer 22 is equipped with a heater for heating the LNG. The vaporizer 22 heats the LNG with the heater and vaporizes it. A hot water heater or a steam heater can be used as the heater. The LNG vaporized by the vaporizer 22 is supplied to the internal combustion engine 11 through the fuel line LF1.

[0024] Here, the liquefied fuel gas, which is in a liquid state within the fuel tank 20, vaporizes within the fuel tank 20 due to natural heat input from the outside. This generates boil-off gas (BOG) within the fuel tank 20. When BOG is generated, the internal pressure of the fuel tank 20 increases. Therefore, in order to protect the fuel tank 20, the BOG needs to be treated. Preferably, this BOG is not simply incinerated, but is effectively utilized as energy generated on the ship. The BOG is supplied to the compressor 25 through the first BOG line LB1.

[0025] The compressor 25 compresses and increases the pressure of the BOG supplied from the fuel tank 20.

[0026] The generator 26 generates electricity using BOG compressed by the compressor 25. The generator 26 may be, for example, a gas-fired engine-driven generator, and generates electricity using the power obtained by burning the supplied BOG. ​​The electricity generated by the generator 26 is supplied to the ship's loads that require electricity. Note that the power generation system 1 of this embodiment may include this generator 26.

[0027] Next, the power generation system 1 of this embodiment will be described. The power generation system 1 comprises an exhaust gas economizer 31 and a binary generator 40.

[0028] The exhaust gas economizer 31 is a steam generator that uses exhaust gas to produce steam. The exhaust gas economizer 31 recovers heat from the exhaust gas E1 from the internal combustion engine 11 to produce steam S1. More specifically, the exhaust gas economizer 31 produces steam S1 by performing heat exchange between the exhaust gas E1 supplied through the exhaust gas line LE1 and water. The exhaust gas E1, whose temperature has decreased after heat exchange in the exhaust gas economizer 31, is supplied to the second evaporator 41B of the binary generator 40, which will be described later.

[0029] The binary generator 40 is a generator that recovers thermal energy through a circulating working medium R1 and generates electricity by utilizing the expansion of the working medium R1. More specifically, the binary generator 40 of this embodiment is an organic Rankine cycle (ORC) type generator that generates electricity by heating and evaporating the working medium R1, which is a low-boiling-point polymer organic working medium, with a heat source fluid, and using the resulting steam to rotate a turbine. In the ORC, the evaporation and condensation of the working medium R1 are repeated.

[0030] The binary generator 40 includes an evaporator 41 that heats and vaporizes the working medium R1 using a heat source fluid, an expander 42 that generates power using the working medium R1 heated and vaporized by the evaporator 41 as a power source, a condenser 43 that cools and condenses the working medium R1 from the expander 42, a circulation pump 44 that sends the working medium R1 from the condenser 43 to the evaporator 41, and a working medium line LR1 through which the working medium R1 that flows through the evaporator 41, expander 42, condenser 43, and circulation pump 44 circulates. Here, a generator 45 is connected to the expander 42. The generator 45 generates electricity in conjunction with the rotation of the expander 42.

[0031] The evaporator 41 comprises a first evaporator 41A and a second evaporator 41B. In this embodiment, it further comprises a third evaporator 41C.

[0032] The first evaporator 41A heats the working fluid R1 through heat exchange between the supercharged air A1 from the supercharger 12 and the working fluid R1. The supercharged air A1 is supplied to the first evaporator 41A through the air line LA1.

[0033] The second evaporator 41B heats the working medium R1 through heat exchange between the exhaust gas E1 from the internal combustion engine 11 and the working medium R1. The second evaporator 41B heats the working medium R1 using the exhaust gas E1 whose temperature has decreased after heat exchange in the exhaust gas economizer 31.

[0034] The third evaporator 41C heats the working medium R1 through heat exchange between the steam generated on the ship and the working medium R1. The third evaporator 41C heats the working medium R1 through heat exchange between the steam S1 generated in the exhaust gas economizer 31, for example, and the working medium R1. The steam undergoing heat exchange in the third evaporator 41C preferably includes, but is not limited to, the steam S1 generated in the exhaust gas economizer 31.

[0035] The expander 42 generates power using the working medium R1, which is heated and vaporized by the first evaporator 41A, the second evaporator 41B, and the third evaporator 41C, as its power source. The expander 42 in this embodiment is a screw-type expander. The high-pressure working medium R1, which has been heated and vaporized, rotates the screw rotor, and the generator 45 generates electricity in conjunction with this rotation. Note that the expander 42 is not limited to a screw type. For example, it may be a scroll type or a turbine type.

[0036] The condenser 43 cools and condenses the low-pressure working fluid R1 from the expander 42. The condenser 43 cools the working fluid R1 by exchanging heat with the coolant W1 supplied through the coolant line LW1. The coolant W1 may be, for example, seawater or the ship's cooling water. In the latter case, a cooler (not shown) that cools fresh water with seawater may be used.

[0037] The circulation pump 44 sends the working medium R1 from the condenser 43 to the evaporator 41.

[0038] Furthermore, a polymeric organic compound with a lower boiling point than water is used as the working fluid R1 circulating in the working fluid line LR1. The working fluid R1 may be 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 natural medium such as 25% aqueous ammonia (boiling point at 1 atm: 38°C) may be used instead of the polymeric organic compound.

[0039] In this embodiment, the ORC of the binary generator 40 is designed such that, for example, when the saturated vapor pressure at the inlet of the expander 42 is 2 MPa and seawater at a temperature of approximately 25-30°C is used as the cooling water W1, the saturated vapor pressure at the outlet of the condenser 43 is 0.2-0.3 MPa. When HFC-245fa is used as the working fluid R1, the outlet temperature of the condenser 43 is generally in the range of 30-40°C.

[0040] The flow rate of the heat source fluid that exchanges heat with the working medium R1 may be adjusted by controlling a flow rate adjustment mechanism such as a valve (not shown). For example, sensors for detecting the temperature and pressure of the working medium R1 may be provided at the outlets of the evaporator 41 and condenser 43, and the flow rate of the heat source fluid may be adjusted based on the detection results of the sensors.

[0041] The power generation system 1 of this embodiment further includes a boiler 32 in addition to the exhaust gas economizer 31 described above as a steam generator. Furthermore, the power generation system 1 of this embodiment further includes a steam header 33.

[0042] The boiler 32 is a device that generates steam S2 using BOG of LNG as fuel, and a marine water-tube boiler is used, for example. The BOG generated in the fuel tank 20 is supplied to the boiler 32 through the second BOG line LB2.

[0043] The second BOG line LB2 is a free-flow line that supplies uncompressed BOG (boiled gas) to the boiler 32. In other words, the second BOG line LB2 is a line that releases the pressure in the fuel tank 20 that has risen due to the generation of BOG, and this line is connected to the boiler 32. The boiler 32 burns the BOG supplied through the second BOG line LB2 to produce steam S2. This makes it possible to effectively utilize BOG as energy generated in the ship.

[0044] Furthermore, in situations where the amount of electricity generated by the generator 26 is sufficient, surplus BOG may be supplied to the boiler 32. For example, a valve 27 provided in the first BOG line LB1 controls the destination of the BOG compressed by the compressor 25, and all or part of the BOG may be supplied to the boiler 32. This allows the boiler 32 to generate more steam S2. In this way, BOG, as energy generated on a ship, can be appropriately distributed and effectively utilized according to the required amount of electricity and steam.

[0045] The steam header 33 is connected to the exhaust gas economizer 31 via the steam line LS1. The steam header 33 is also connected to the boiler 32 via the steam line LS2. Within the steam header 33, the steam S1 generated by the exhaust gas economizer 31 and the steam S2 generated by the boiler 32 are combined. For example, steam S1 and steam S2 are combined within the steam header 33, and the combined steam S3 is supplied to the third evaporator 41C, etc., via the steam line LS3A.

[0046] Here, the third evaporator 41C may use steam S1 generated by the exhaust gas economizer 31 or steam S2 generated by the boiler 32 as the steam that exchanges heat with the working medium R1. Alternatively, as shown in this embodiment, steam S3 containing steam S1 and steam S2 may be used.

[0047] The steam used in the third evaporator 41C is not limited to this; any steam generated on the ship is acceptable. For example, the steam used in the third evaporator 41C may be steam generated by an auxiliary boiler (not shown). The fuel for the auxiliary boiler may be gaseous fuel or oil fuel.

[0048] Furthermore, some of the steam S1 generated by the exhaust gas economizer 31 and the steam S2 generated by the boiler 32 may be supplied to the third evaporator 41C via the steam line LS3A, and some may be supplied to the steam demand destinations D on the ship (heating of fuel oil and lubricating oil, heating of air conditioning, etc.) via the steam line LS3B. The amount of steam supplied to each destination is adjusted by valves 34, 35, etc., which serve as supply amount adjustment means.

[0049] The power generation system 1 of this embodiment includes a control unit 100 for performing various controls. The control unit 100 controls the power generation system 1 of this embodiment, the internal combustion engine 11, etc., so that the energy generated in the ship can be effectively utilized. The control unit 100 may, for example, control valves, etc., provided in each line based on the detection results of sensors attached to each part.

[0050] Next, we will explain the flow of each fluid circulating through each line.

[0051] First, let's explain the flow of LNG as liquefied fuel gas. The LNG flowing through fuel line LF1 is supplied from fuel tank 20 and flows in the following order: high-pressure pump 21, vaporizer 22, and internal combustion engine 11. Fuel line LF1 is the line that connects fuel tank 20, high-pressure pump 21, vaporizer 22, and internal combustion engine 11.

[0052] The LNG stored in the fuel tank 20 is pressurized by the high-pressure pump 21 and supplied to the vaporizer 22. The LNG vaporized by the vaporizer 22 is supplied to the internal combustion engine 11.

[0053] Next, the flow of air A1 will be explained. Air A1 flowing through air line LA1 is compressed by the supercharger 12 and flows in the following order: first evaporator 41A, intercooler 13, and internal combustion engine 11. Air line LA1 is the line connecting the supercharger 12, the first evaporator 41A, the intercooler 13, and the internal combustion engine 11.

[0054] The air A1 taken into the supercharger 12 is compressed and supplied to the first evaporator 41A as supercharged air A1. The compressed and high-temperature supercharged air A1 exchanges heat with the working medium R1 in the first evaporator 41A, heating the working medium R1. The supercharged air A1, whose temperature has decreased due to the heat exchange, is further cooled to a predetermined temperature in the intercooler 13 and sent to the internal combustion engine 11.

[0055] The temperature of the supercharged air A1 flowing into the first evaporator 41A may be, for example, between 50°C and 250°C, and the temperature of the supercharged air A1 supplied to the internal combustion engine 11 may be, for example, between 40°C and 50°C. The temperature of the supercharged air A1 flowing into the first evaporator 41A may be, for example, around 150°C.

[0056] If the supercharged air A1 is supplied to the internal combustion engine 11 while still hot, the heat load on the internal combustion engine 11 will increase. Also, the amount of air being charged will decrease, and the output will decrease. Therefore, the supercharged air A1 needs to be cooled. In this embodiment, the heat of compression of the supercharged air A1 compressed by the supercharger 12 is not immediately used as waste heat in the intercooler 13, but is first used as a heat source fluid for the first evaporator 41A. In this way, by recovering the heat of compression of the supercharged air A1 as waste heat in the first evaporator 41A, the energy generated in the ship can be effectively utilized.

[0057] Next, the flow of exhaust gas E1 will be explained. Exhaust gas E1 flowing through exhaust gas line LE1 is discharged from the internal combustion engine 11 and flows in the following order: exhaust turbine, which is the power source for the supercharger 12, exhaust gas economizer 31, and second evaporator 41B. Exhaust gas line LE1 is the line connecting the internal combustion engine 11, supercharger 12, exhaust gas economizer 31, and second evaporator 41B.

[0058] The exhaust gas E1 discharged from the internal combustion engine 11 drives the exhaust turbine in the supercharger 12. The exhaust gas E1, with its exhaust pressure recovered by being used as the driving force for the exhaust turbine, is supplied to the exhaust gas economizer 31. In the exhaust gas economizer 31, the exhaust gas E1 undergoes heat exchange with water to generate steam S1. The exhaust gas E1, whose temperature has decreased due to the heat exchange in the exhaust gas economizer 31, is supplied to the second evaporator 41B. The exhaust gas E1 undergoes heat exchange with the working medium R1, heating the working medium R1. The exhaust gas E1, whose temperature has decreased further due to the heat exchange in the second evaporator 41B, is discharged from the second evaporator 41B.

[0059] The temperature of the exhaust gas E1 flowing into the exhaust gas economizer 31 may be, for example, between 180°C and 400°C, and the temperature of the exhaust gas E1 flowing into the second evaporator 41B may be, for example, between 150°C and 300°C. The temperature of the exhaust gas E1 flowing into the second evaporator 41B may be, for example, around 170°C.

[0060] When the internal combustion engine 11 is operated, exhaust gas E1 is generated. As shown in this embodiment, the exhaust pressure of the exhaust gas E1 is recovered by driving the turbocharger 12, the waste heat of the exhaust gas E1 is first recovered by the exhaust gas economizer 31, and then secondarily recovered by the second evaporator 41B, thereby enabling efficient and effective utilization of the energy generated in the ship.

[0061] Next, the flow of BOG will be explained. BOG flowing through the first BOG line LB1 is discharged from the fuel tank 20 and supplied to the generator 26 and boiler 32 via the compressor 25. BOG flowing through the second BOG line LB2 is supplied directly from the fuel tank 20 to the boiler 32. The first BOG line LB1 connects the fuel tank 20 and the compressor 25, and branches off from there to connect to the generator 26 and boiler 32. The second BOG line LB2 is a line that directly connects the fuel tank 20 and the boiler 32.

[0062] The BOG flowing through the first BOG line LB1 is pressurized by the compressor 25 until it reaches the pressure required by the generator 26, and then supplied to the generator 26. The BOG is burned in the generator 26, thereby generating electricity.

[0063] The BOG flowing through the first BOG line LB1 is supplied to the boiler 32 through the control of valve 27. In addition, the BOG generated in the fuel tank 20 is supplied to the boiler 32 through the second BOG line LB2. The BOG is burned in the boiler, thereby generating steam S2.

[0064] Next, we will explain the flow of steam S1, steam S2, and steam S3.

[0065] Steam S1 generated by the exhaust gas economizer 31 is supplied to the steam header 33 through the steam line LS1. Steam S2 generated by the boiler 32 is supplied to the steam header 33 through the steam line LS2. The steam S1 and steam S2 collected in the steam header are supplied as steam S3 to the third evaporator 41C through the steam line LS3A. Steam S3 is also supplied to the steam demand destinations D on the ship through the steam line LS3B. The amount of steam S3 supplied to each destination is adjusted by valves 34, 35, etc., which serve as supply adjustment means. Furthermore, the temperature of the steam S3 that flows into the third evaporator 41C and exchanges heat with the working medium R1 is preferably 100°C or higher.

[0066] Next, the flow of the working fluid R1 will be explained. The working fluid R1 circulates through the working fluid line LR1, which connects the evaporator 41, the expander 42, the condenser 43, and the circulation pump 44.

[0067] The working medium R1 is heated and vaporized in the evaporator 41. The vaporized high-pressure working medium R1 rotates the screw rotor of the expander 42, driving the generator 45. The low-pressure working medium R1 that has passed through the screw rotor of the expander 42 is cooled and condensed in the condenser 43. The condensed working medium R1 is sent back to the evaporator 41 by the circulation pump 44. In this way, the working medium R1 repeatedly evaporates and condenses while circulating through the working medium line LR1.

[0068] In this embodiment, as described above, the evaporator 41 includes a first evaporator 41A, a second evaporator 41B, and a third evaporator 41C. Therefore, the working fluid R1 flows in the order of the first evaporator 41A, the second evaporator 41B, and the third evaporator 41C. In the first evaporator 41A, the working fluid R1 undergoes heat exchange with the supercharged air A1, and its temperature rises. In the second evaporator 41B, the working fluid R1 undergoes heat exchange with the exhaust gas E1, and its temperature rises further. In the third evaporator 41C, the working fluid R1 undergoes heat exchange with steam, and its temperature rises further. In this way, by providing multiple evaporators, multiple different heat source fluids generated in the ship can be effectively utilized as energy, and the working fluid R1 can be heated in stages.

[0069] Furthermore, the temperature of the working medium R1 flowing out from the third evaporator 41C may be, for example, around 120°C, and the temperature of the working medium R1 flowing out from the condenser 43 may be, for example, around 40°C.

[0070] The steam S3, after being used as the heat source fluid for the third evaporator 41C, is cooled with seawater in the condenser and recovered as condensate. This condensate can be reused as feedwater for the exhaust gas economizer 31 and boiler 32.

[0071] <Example 1> Since unused thermal energy often remains in the steam S3 after use at customer D, it is desirable to make effective use of this thermal energy. Specifically, the steam S3 after use at customer D is collected and reused as a heat source fluid for the binary generator 40. In this case, a fourth evaporator is added to the ORC through which the working fluid R1 circulates. The fourth evaporator is connected, for example, between the third evaporator 41C and the expander 42. After use as a heat source fluid in the fourth evaporator, the steam S3 is cooled in a condenser, recovered as condensate drain, and reused as feedwater for the exhaust gas economizer 31 and boiler 32.

[0072] <Modification 2> When seawater is used as the coolant W1 in the condenser 43 of the binary generator 40, considering the high seawater temperature, the outlet temperature of the working fluid R1 in the condenser 43 is limited to around 30-40°C. Lowering the outlet temperature of the working fluid R1 below this temperature increases the amount of heat absorbed in the evaporator 41, thereby increasing the amount of power generated. For example, lowering the outlet temperature of the working fluid R1 to around 10-20°C, or by 20°C, increases the amount of power generated by approximately 20-30%.

[0073] Therefore, it is preferable to install a supercooler to increase the amount of heat dissipated by the working medium R1. Specifically, a supercooler is connected between the condenser 43 and the circulation pump 44 to exchange heat between the working medium R1 and the LNG supplied from the high-pressure pump 21. By utilizing the amount of heat contained in the working medium R1 after passing through the condenser 43 as vaporization energy for the LNG, the temperature of the working medium R1 flowing into the evaporator 41 can be lowered. At the same time, the thermal energy consumed by heaters and other devices in the vaporizer 22 will be reduced compared to before the supercooler was installed.

[0074] The heat lost due to the temperature reduction of the working fluid R1 in the supercooler can be recovered in the fourth evaporator in Modification 1. Furthermore, if additional heat recovery is possible, a fifth evaporator may be added to the ORC. The fifth evaporator is connected, for example, between the fourth evaporator and the expander 42. As the heat source fluid for the fifth evaporator, for example, warm wastewater used as jacket cooling water for the internal combustion engine 11 can be utilized.

[0075] <Variation 3> In this embodiment, binary power generation is performed by recovering the waste heat from multiple heat source fluids (supercharged air A1, exhaust gas E1) generated when the internal combustion engine 11, which serves as the main engine, is in operation. However, when the ship is at anchor or sailing at low speed, these heat source fluids become insufficient. When the ship is at anchor or sailing at low speed, the amount of steam used on board tends to decrease, so it is not a problem if the amount of steam S1 generated by the exhaust gas economizer 31 decreases. On the other hand, when liquefied fuel gas is used in the internal combustion engine 11, a boiler 32 is installed to process the BOG that is generated on a regular basis. However, when the ship is at anchor or sailing at low speed, the steam S2 generated by the boiler 32 becomes surplus.

[0076] Therefore, when the ship is at anchor or sailing at low speed, it is preferable to switch the evaporator 41 being used and recover heat with the binary generator 40. Specifically, the supply of supercharged air A1 to the first evaporator 41A is bypassed, and the supply of exhaust gas E1 to the second evaporator 41B is also bypassed. Then, only the steam S2 generated in the boiler 32 is supplied to the third evaporator 41C to operate the binary generator 40. This makes it possible to effectively utilize the energy generated on the ship.

[0077] Furthermore, valve 34 of steam line LS3A may be used as an excess steam control valve to control the supply of excess steam to the third evaporator 41C. The control unit 100 may control the excess steam control valve based on information indicating conditions such as when the ship is anchored or sailing at low speed.

[0078] <Modification 4> In this embodiment, the exhaust gas economizer 31 recovers heat from the exhaust gas E1 and generates steam S1. However, the exhaust gas E1 from the internal combustion engine 11, which serves as the main engine, is hot and has a large gas volume. Since the amount of steam used on board during normal ship navigation fluctuates, if the amount of heat recovered by the exhaust gas economizer 31 is too large, the generated steam S1 tends to become surplus. Furthermore, if the emergency fuel of the dual-fuel internal combustion engine 11 is switched from heavy fuel oil to light fuel oil (marine gas oil), fuel heating becomes unnecessary, and the surplus steam increases.

[0079] Therefore, it is preferable to adjust the amount of heat recovered in the exhaust gas economizer 31 and the amount of heat recovered in the second evaporator 41B. Specifically, a bypass line to the exhaust gas economizer 31 is connected to the exhaust gas line LE1. Then, the amount of exhaust gas E1 supplied to the exhaust gas economizer 31 and the bypass amount are adjusted so that the inlet temperature of the exhaust gas E1 supplied to the second evaporator 41B becomes the set temperature Ti. This makes it possible to appropriately adjust the amount of steam generated by the exhaust gas economizer 31 and the amount of electricity generated by the binary generator 40.

[0080] In this case, the set temperature Ti may be changed each time based on the amount of steam required on board, and the amount of exhaust gas E1 supplied to the exhaust gas economizer 31 and the bypass amount may be increased or decreased. If the set temperature Ti is fixed, excess steam may be generated due to fluctuations in the amount of steam used on board. In this case, the excess steam may be introduced into the third evaporator 41C to recover heat and increase the amount of electricity generated by the binary generator 40.

[0081] <Modification 5> The heavy fuel oil (e.g., C heavy oil) used as emergency fuel for the dual-fuel internal combustion engine 11 has a high sulfur content. When using fuel with a high sulfur content, corrosion of the exhaust gas economizer 31 and the second evaporator 41B becomes a problem. In particular, if corrosion of the second evaporator 41B causes leakage of the working fluid R1, the binary generator 40 will become inoperable.

[0082] Therefore, it is preferable to take measures to prevent corrosion of the exhaust gas economizer 31 and the second evaporator 41B. Specifically, the exhaust gas temperature at the outlet of the exhaust gas economizer 31 is detected, and the flow rate of the feedwater is adjusted so that this temperature is equal to or higher than the set temperature To1 (for example, 200°C). For example, the rotation speed of the feedwater pump (not shown) is increased to reduce the amount of heat absorbed by the feedwater, thereby ensuring that the temperature of the exhaust gas E1 inside the exhaust gas economizer 31 does not fall below the acid dew point.

[0083] Furthermore, the outlet exhaust gas temperature of the second evaporator 41B is detected, and the flow rate of the working medium R1 is adjusted so that this temperature is equal to or higher than the set temperature To2 (for example, 150°C). For example, the rotational speed of the circulation pump 44 is increased to reduce the amount of heat absorbed by the working medium R1, thereby ensuring that the temperature of the exhaust gas E1 inside the second evaporator 41B does not fall below the acid dew point. In this operation, the set temperature To2 is set to 150°C when using fuel oil with a sulfur content of 3.5%, 130°C when using fuel oil with a sulfur content of 0.5%, and 120°C when using fuel oil with a sulfur content of 0.1%.

[0084] The ship power generation system 1 of this embodiment, as described above, provides the following effects.

[0085] (1) The ship power generation system 1 of this embodiment is a ship power generation system 1 used in a ship S which is equipped with an internal combustion engine 11 and an exhaust turbine type supercharger 12 which supplies supercharged air A1 to the internal combustion engine 11, and comprises an exhaust gas economizer 31 which generates steam S1 using exhaust gas E1 from the internal combustion engine 11, and a binary generator 40 which recovers thermal energy via a circulating working medium R1 and generates electricity based on the expansion of the working medium R1, and the binary generator 40 has a first evaporator 41A which heats the working medium R1 by heat exchange between the supercharged air A1 from the supercharger 12 and the working medium R1, and a second evaporator 41B which heats the working medium R1 by heat exchange between the exhaust gas E1 from the internal combustion engine 11 and the working medium R1, and the exhaust gas E1 from the internal combustion engine 11 flows in the order of exhaust turbine, which is the driving source of the supercharger 12, exhaust gas economizer 31, and second evaporator 41B.

[0086] More specifically, in the first evaporator 41A, the working medium R1 is heated by heat exchange between the supercharged air A1 from the supercharger 12 and the working medium R1, and further in the second evaporator 41B, the working medium R1 is heated by heat exchange between the exhaust gas E1 from the internal combustion engine 11 and the working medium R1, thereby efficiently recovering the thermal energy of the supercharged air A1 and exhaust gas E1 in the binary generator 40. Furthermore, since the exhaust gas economizer 31 generates steam S1 using the still-high-temperature exhaust gas E1 after it has passed through the supercharger 12 but before it flows into the second evaporator 41B, the energy generated on the ship can be effectively utilized.

[0087] In binary power generation, the working fluid typically used is one with a lower boiling point than water. Therefore, even with exhaust gas E1 whose temperature has decreased after heat exchange in the exhaust gas economizer 31, the second evaporator 41B can still heat the working fluid R1. Thus, the energy generated on the ship can be efficiently and effectively utilized.

[0088] (2) The binary generator 40 of the ship power generation system 1 of this embodiment further has a third evaporator 41C, which heats the working medium R1 through heat exchange between the steam S1 generated by the exhaust gas economizer 31 and the working medium R1. In this way, in the third evaporator 41C, the working medium R1 is heated through heat exchange between the steam S1 generated by the exhaust gas economizer 31 which utilizes the exhaust gas E1 from the internal combustion engine 11 and the working medium R1, so that the energy generated on the ship is recovered more efficiently in the binary generator 40.

[0089] (3) The internal combustion engine 11 of the ship power generation system 1 of this embodiment is an internal combustion engine that uses liquefied fuel gas as fuel, and further comprises a boiler 32 that generates steam S2 using boil-off gas (BOG) of liquefied fuel gas as fuel, and the binary generator 40 further comprises a third evaporator 41C, which heats the working medium R1 by heat exchange between the steam S2 generated in the boiler 32 and the working medium R1. In this way, in the third evaporator 41C, the working medium R1 is heated by heat exchange between the steam S2 generated by the boiler 32 that uses BOG of liquefied fuel gas used in the internal combustion engine 11 and the working medium R2, so that the energy generated on the ship is recovered more efficiently in the binary generator 40.

[0090] <Second Embodiment> Next, a second embodiment will be described with reference to the drawings. Note that the same configuration as in the first embodiment will not be described. Figure 2 is a diagram showing an overview of the shipboard power generation system 1 according to the second embodiment of the present invention.

[0091] As shown in Figure 2, the ship power generation system 1 of this embodiment further comprises a steam expander generator 50 and a steam binary generator 60. In this embodiment, the evaporator 41 of the binary generator 40 is composed of a first evaporator 41A and a second evaporator 41B. However, the evaporator 41 of the binary generator 40 may also have a third evaporator 41C, as in the first embodiment.

[0092] The steam expander generator 50 is a generator that generates electricity by converting the expansion of steam into rotational force. The steam expander generator 50 may have, for example, a twin-screw type expansion mechanism. In this case, the differential pressure between the supply pressure of the steam flowing into the supply port of the steam expander generator 50 and the exhaust pressure on the exhaust port side of the steam expander generator 50 causes a pair of screw rotors arranged inside the rotor casing to rotate. This rotational power is transmitted to the generator shaft to generate electricity.

[0093] This steam expander generator 50 basically generates electricity by recovering the pressure energy of steam S3, rather than recovering thermal energy from the steam S3. Therefore, the steam S4 discharged from the steam expander generator 50 has a lower pressure than the steam S3 that flowed into the steam expander generator 50, and its saturated steam temperature is corresponding to the reduced pressure. The steam S3 that flows into the intake port of the steam expander generator 50 becomes depressurized steam S4, which is discharged from the exhaust port of the steam expander generator 50 and supplied to the steam binary generator 60. In this way, the steam expander generator 50 also functions as a pressure reducing device.

[0094] The steam expander generator 50 generates electricity using, for example, steam S1 produced by the exhaust gas economizer 31 or steam S2 produced by the boiler 32. However, the steam used is not limited to these.

[0095] The steam binary generator 60 is a binary generator that recovers thermal energy from steam as a heat source fluid via a circulating working medium R2 and generates electricity based on the expansion of the working medium R2. More specifically, the steam binary generator 60 in this embodiment is an organic Rankine cycle (ORC) type generator that generates electricity by heating and vaporizing the working medium R2, which is a low-boiling-point polymer organic working medium, with steam as a heat source fluid, and rotating a screw rotor with the vapor of the working medium R2 produced by vaporization. The steam binary generator 60 in this embodiment generates electricity using depressurized steam S4 after use in the steam expander generator 50 as a heat source fluid.

[0096] The steam binary generator 60 comprises an evaporator 61 that heats and vaporizes the working medium R2 using steam S4, an expander 62 that generates power using the working medium R2 heated and vaporized by the evaporator 61 as a power source, a condenser 63 that cools and condenses the working medium R2 from the expander 62, a circulation pump 64 that sends the working medium R2 from the condenser 63 to the evaporator 61, and a working medium line LR2 through which the working medium R2 flowing through the evaporator 61, expander 62, condenser 63, and circulation pump 64 circulates. Here, a generator 65 is connected to the expander 62. The generator 65 generates electricity in conjunction with the rotation of the expander 62.

[0097] The evaporator 61 heats the working fluid R2 through heat exchange between the depressurized steam S4 used by the steam expander generator 50 and the working fluid R2. The steam S4 is supplied to the evaporator 61 through the steam line LS4.

[0098] The expander 62 generates power using the working medium R2, which is heated and vaporized by the evaporator 61, as its power source. In this embodiment, the expander 62 is a screw-type expander. The high-pressure working medium R2, which has been heated and vaporized, rotates the screw rotor, and the generator 65 generates electricity in conjunction with this rotation. Note that the expander 62 is not limited to a screw type. For example, it may be a scroll type or a turbine type.

[0099] The condenser 63 cools and condenses the low-pressure working fluid R2 from the expander 62. The condenser 63 cools the working fluid R2 by exchanging heat with the coolant W2 supplied through the coolant line LW2. For the coolant W2, for example, seawater or the cooling water on board the ship may be used. In this embodiment, a cooler 71 is provided that cools the coolant W2 with seawater, and this cooler 71 circulates the coolant W2 between itself and the condenser 63.

[0100] The circulation pump 64 sends the working medium R2 from the condenser 63 to the evaporator 61.

[0101] Furthermore, a polymeric organic compound with a lower boiling point than water is used as the working fluid R1 circulating in the working fluid line LR1. The working fluid R1 may be 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 natural medium such as 25% aqueous ammonia (boiling point at 1 atm: 38°C) may be used instead of the polymeric organic compound.

[0102] The flow rates of the steam S4 and coolant W2 that exchange heat with the working medium R2 may be adjusted by controlling a flow rate adjustment mechanism such as a valve (not shown). For example, sensors for detecting the temperature and pressure of the working medium R2 may be provided at the outlets of the evaporator 61 and condenser 63, and the flow rates of these fluids may be adjusted based on the detection results of the sensors.

[0103] The steam header 33 is connected to the exhaust gas economizer 31 via the steam line LS1. The steam header 33 is also connected to the boiler 32 via the steam line LS2. Within the steam header 33, the steam S1 generated by the exhaust gas economizer 31 and the steam S2 generated by the boiler 32 are combined. For example, steam S1 and steam S2 are combined within the steam header 33, and the combined steam S3 is supplied to the steam expander generator 50, etc., via the steam line LS3C.

[0104] Here, the steam expander generator 50 may use steam S1 generated by the exhaust gas economizer 31 or steam S2 generated by the boiler 32 as the steam to obtain power. Alternatively, as shown in this embodiment, steam S3 containing steam S1 and steam S2 may be used.

[0105] The steam used in the steam expander generator 50 is not limited to this; any steam generated on a ship is acceptable. For example, the steam used in the steam expander generator 50 may be steam generated by an auxiliary boiler (not shown). The fuel for the auxiliary boiler may be gaseous fuel or oil fuel.

[0106] Furthermore, some of the steam S1 generated by the exhaust gas economizer 31 and the steam S2 generated by the boiler 32 may be supplied to the steam expander generator 50 via the steam line LS3C, and some may be supplied to the steam demand destinations D on the ship (heating of fuel oil and lubricating oil, heating of air conditioning, etc.) via the steam line LS3B. The amount of steam supplied to each destination is adjusted by valves 36, 35, etc., which serve as supply amount adjustment means.

[0107] The steam line may also include a steam line LS3D for supplying steam to the steam binary generator 60 without going through the steam expander generator 50. In this case, a pressure reducing valve 37 is provided in the steam line LS3D.

[0108] Next, we will explain the flow of steam S1, steam S2, steam S3, and steam S4.

[0109] Steam S1 generated by the exhaust gas economizer 31 is supplied to the steam header 33 through the steam line LS1. Steam S2 generated by the boiler 32 is supplied to the steam header 33 through the steam line LS2. The steam S1 and steam S2 collected in the steam header are supplied as steam S3 to the steam expander generator 50 through the steam line LS3C. Steam S3 is also supplied to the steam demand destinations D on the ship through the steam line LS3B. The amount of steam S3 supplied to each destination is adjusted by valves 36, 35, etc., which serve as supply adjustment means.

[0110] The steam S3 is pressure-recovered in the steam expander generator 50 and supplied to the steam binary generator 60 through the steam line LS4 as depressurized steam S4.

[0111] In cases where power generation by the steam expander generator 50 is not required, the steam S3 may be supplied to the steam binary generator 60 through the steam line LS3D. In this case, the steam S3 is depressurized by the pressure reducing valve 37 and supplied to the steam binary generator 60 as depressurized steam S4.

[0112] Furthermore, the pressure P4 of the steam S4 flowing into the evaporator 61 of the steam binary generator 60 is lower than the pressure P3 of the steam S3 flowing into the steam expander generator 50. For example, pressure P3 is between 0.4 MPa and 0.95 MPa, and pressure P4 is between 0.1 MPa and 0.35 MPa. Furthermore, the temperature T4 of the steam S4 flowing into the evaporator 61 of the steam binary generator 60 is lower than the temperature T3 of the steam S3 flowing into the steam expander generator 50. For example, temperature T3 is between 152°C and 182°C, and temperature T4 is between 100°C and 148°C. However, the decrease in steam temperature due to passing through the steam binary generator 60 is limited, and the thermal energy of this steam can be fully utilized in the steam binary generator 60.

[0113] Next, the flow of the working fluid R2 will be explained. The working fluid R2 circulates through the working fluid line LR2, which connects the evaporator 61, the expander 62, the condenser 63, and the circulation pump 64.

[0114] The working medium R2 is heated by steam S4 in the evaporator 61 and vaporizes. The vaporized high-pressure working medium R2 drives the screw rotor of the expander 62 to generate electricity. The low-pressure working medium R2 that has passed through the screw rotor of the expander 62 is cooled and condensed in the condenser 63. The condensed working medium R2 is sent back to the evaporator 61 by the circulation pump 64. In this way, the working medium R2 repeatedly evaporates and condenses while circulating in the working medium line LR2.

[0115] Furthermore, the above-described modifications 1 to 5 can also be applied to this embodiment.

[0116] <Variation 6> The steam S3 used at customer D may be reused as the heat source fluid for the steam binary generator 60. In this case, a second evaporator is added to the ORC through which the working fluid R2 circulates. The second evaporator is connected, for example, between the evaporator 61 and the expander 62. The steam S3 used as the heat source fluid for the second evaporator can be recovered as condensate drain, as in Modification 1, and reused as feedwater for the exhaust gas economizer 31 or boiler 32.

[0117] According to the ship power generation system 1 of this embodiment described above, in addition to the above-mentioned (1) to (3), the following effects are achieved.

[0118] (4) The shipboard power generation system 1 of this embodiment further comprises a steam expander generator 50 that generates electricity by converting the expansion of steam into rotational force, and the steam expander generator 50 generates electricity using steam S1 generated by the exhaust gas economizer 31. In this way, since the steam expander generator 50 generates electricity using steam S1 generated by the exhaust gas economizer 31 which utilizes exhaust gas E1 from the internal combustion engine 11, the energy generated on the ship is utilized more effectively.

[0119] (5) The internal combustion engine 11 of the ship's power generation system 1 of this embodiment is an internal combustion engine that uses liquefied fuel gas as fuel, and further comprises a boiler 32 that generates steam S2 using boil-off gas (BOG) of liquefied fuel gas as fuel, and a steam expander generator 50 that generates electricity by converting the expansion of steam into rotational force, the steam expander generator 50 generating electricity using the steam S2 generated by the boiler 32. In this way, the steam expander generator 50 generates electricity using the steam S2 generated by the boiler 32 that uses BOG of liquefied fuel gas used in the internal combustion engine 11 as fuel, so that the energy generated on the ship is utilized more effectively.

[0120] (6) The shipboard power generation system 1 of this embodiment further includes a steam binary generator 60 that generates electricity using the steam S4 used in the steam expander generator 50 as a heat source fluid. In this way, by performing steam cascade power generation using the steam expander generator 50 and the steam binary generator 60, the steam generated on the ship can be effectively utilized. In the steam binary generator 60, the steam that exchanges heat with the working fluid R2 may be low-pressure steam. On the other hand, the steam used in the steam expander generator 50 is required to be at a medium pressure or higher. Therefore, the steam expander generator 50 generates electricity using steam at a medium pressure or higher that is generated on the ship, and then the steam binary generator 60 generates electricity using the reduced-pressure steam after it has been used in the steam expander generator 50, thereby effectively utilizing the steam generated on the ship and performing efficient power generation.

[0121] (7) The steam binary generator 60 of the ship power generation system 1 of this embodiment has an evaporator 61 that heats the working medium R2 by heat exchange between the steam S4 used in the steam expander generator 50 and the working medium R2. This ensures that heat exchange is properly performed between the steam S4 used in the steam expander generator 50 and the working medium R2 circulating in the steam binary generator 60.

[0122] Although preferred embodiments of the shipboard power generation system of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate. Furthermore, it is possible to combine multiple embodiments. [Explanation of Symbols]

[0123] S ship 1. Shipboard power generation system 11. Internal combustion engine (main engine) 12 Supercharger 13 Intercooler 20 fuel tanks 31 Exhaust gas economizer 32 Boilers 40 Binary Generators 41 Evaporator 41A First Evaporator 41B Second Evaporator 41C Third Evaporator 42 Expander 43 Condenser 44 Circulation pump 45 Generators 50 Steam Expander Generator 60 Steam Binary Generator 61 Evaporator 62 Expander 63 Condenser 64 Circulation pump 65 Generators R1, R2 refrigerants A1 Air, supercharged air (compressed air) E1 exhaust gas LNG (Liquefied Natural Gas) S1, S2, S3, S4 Steam

Claims

1. A ship power generation system for use in a ship comprising an internal combustion engine, an exhaust turbine type supercharger that supplies supercharged air to the internal combustion engine, and an exhaust gas economizer that generates steam using exhaust gas from the internal combustion engine, The system includes a binary generator that recovers thermal energy through a circulating working medium and generates electricity based on the expansion of the working medium, The aforementioned binary generator, A first evaporator that heats the working medium by heat exchange between the supercharged air from the supercharger and the working medium, It has a second evaporator that heats the working medium by heat exchange between the exhaust gas from the internal combustion engine and the working medium, The exhaust gas from the internal combustion engine flows in the following order: the exhaust turbine, which is the driving source for the supercharger; the exhaust gas economizer; and the second evaporator. A shipboard power generation system in which the heating of the working medium is performed in the order of heating in the first evaporator and then heating in the second evaporator.

2. The binary generator further comprises a third evaporator, The ship power generation system according to claim 1, wherein the third evaporator heats the working medium by heat exchange between the steam generated in the exhaust gas economizer and the working medium.

3. The internal combustion engine uses liquefied fuel gas as fuel, and the ship is equipped with a boiler that generates steam using the boil-off gas of the liquefied fuel gas as fuel. The binary generator further comprises a third evaporator, The ship power generation system according to claim 1, wherein the third evaporator heats the working medium by heat exchange between the steam generated in the boiler and the working medium.

4. It is further equipped with a steam expander generator that converts the expansion of steam into rotational force to generate electricity. The ship's power generation system according to any one of claims 1 to 3, wherein the steam expander generator generates electricity using steam produced by the exhaust gas economizer.

5. The internal combustion engine uses liquefied fuel gas as fuel, and the ship is equipped with a boiler that generates steam using the boil-off gas of the liquefied fuel gas as fuel. It is further equipped with a steam expander generator that converts the expansion of steam into rotational force to generate electricity. The ship's power generation system according to any one of claims 1 to 3, wherein the steam expander generator generates electricity using steam produced in the boiler.

6. The shipboard power generation system according to claim 4 or 5, further comprising a steam binary generator that generates electricity using the steam used in the steam expander generator as a heat source fluid.

7. The shipboard power generation system according to claim 6, wherein the steam binary generator has an evaporator that heats the working medium circulating in the steam binary generator by heat exchange between the steam used in the steam expander generator and the working medium circulating in the steam binary generator.

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