JP2023093168A - Marine power generation system - Google Patents

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 comprising a steam generation part 30 such as a boiler or an exhaust gas economizer, and comprises: a steam expander power generator 50 for generating power by converting expansion of steam generated by the steam generation part 30, into turning force; and a steam binary power generator 60 for generating power by using steam S4 used in the steam expander power generator 50, as heat source fluid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a marine power generation system.

Conventionally, marine power generation systems are known. For example, Patent Literature 1 discloses a marine power generation system having an air cooler that uses air to preheat feed water and a waste heat boiler that uses exhaust gas to vaporize the preheated water. .

JP-A-55-25590

In the marine power generation system of Patent Document 1, steam generated by the waste heat boiler can be used to rotate a steam turbine to generate power. However, it cannot be said that the marine power generation system of Cited Document 1 makes effective use of the energy generated in the ship.

SUMMARY OF THE INVENTION An object of the present invention is to provide a marine power generation system capable of effectively utilizing energy generated in a ship.

The present invention provides a marine power generation system (for example, a marine power generation system 1) for use in a ship including a steam generator (for example, a steam generator 30), wherein expansion of steam generated by the steam generator is A steam expander power generator (e.g., steam expander power generator 50) that converts to rotational force to generate power, and steam (e.g., steam S4) after use in the steam expander power generator is used as a heat source fluid to generate power. and a binary steam generator (eg, binary steam generator 60).

In addition, the steam binary generator includes an evaporator (eg, evaporator 61 ).

In addition, the steam generation unit includes a boiler (eg, boiler 32) that generates steam (eg, steam S2) using the boil-off gas of the liquefied fuel gas as fuel, and the steam expander generator is generated by the boiler. It is preferable that the steam binary generator converts the expanded steam into rotational force to generate power, and the steam binary generator generates power using the steam (for example, steam S4) used in the steam expander generator as a heat source fluid.

In addition, the steam generation unit includes an exhaust gas economizer (eg, exhaust gas economizer 31) that generates steam (eg, steam S1) using exhaust gas (eg, exhaust gas E1) from an internal combustion engine (eg, internal combustion engine 11) of the ship. wherein the steam expander generator converts the expansion of the steam generated by the exhaust gas economizer into rotational force to generate power, and the steam binary generator converts the steam used in the steam expander generator to a rotational force Power generation is preferably performed using (for example, steam S4) as the heat source fluid.

ADVANTAGE OF THE INVENTION According to this invention, the power generation system for ships which can utilize the energy which generate|occur|produces in a ship effectively can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the marine power generation system of embodiment of this invention.

Hereinafter, a marine power generation system 1 according to an embodiment of the present invention will be described with reference to the drawings. The term "line" used herein is a general term for lines through which fluid can flow, such as channels, routes, and pipelines.

FIG. 1 is a schematic diagram showing a ship S equipped with a marine power generation system 1 of this embodiment. A marine power generation system 1 of the present embodiment is a power generation system 1 used in a ship S having a steam generator 30 . 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 carburetor 22, a compressor 25 , a generator 26 , a steam generator 30 , a steam header 33 , and a binary generator 40 .

The internal combustion engine 11 is, for example, a main engine for obtaining power for propelling a ship. The internal combustion engine 11 of this embodiment is a well-known diesel engine in which a cylinder is held in a main machine box (not shown) and a piston is fitted in the cylinder so as to be able to move back and forth. The internal combustion engine 11 sucks supercharged air A1 (compressed air A1) sent from an air line LA1 into a cylinder, compresses it with a piston, and injects fuel into the high-pressure air to cause explosive combustion, thereby causing the piston to ignite. Drive 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 .

The internal combustion engine 11 of this embodiment uses liquefied fuel gas as fuel. Liquefied fuel gas is supplied from a fuel tank 20, which will be 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 this embodiment, LNG is used.

The supercharger 12 is an exhaust turbine type turbocharger and feeds supercharged air A<b>1 to the internal combustion engine 11 . The supercharger 12 takes in the air A1 by the rotational force of the exhaust turbine that rotates due to the flow of the exhaust gas E1 discharged from the internal combustion engine 11, and compresses the air A1. Compressed supercharged air A1 is sent to internal combustion engine 11 through air line LA1.

The intercooler 13 cools the supercharged air A<b>1 sent to the internal combustion engine 11 . The intercooler may be water-cooled or air-cooled. In the case of a water-cooled system, seawater may be used as the coolant. In this embodiment, supercharged air A1 supplied from the supercharger 12 is cooled by a first evaporator 41A, which will be described later, and then supplied to the intercooler 13 and further cooled.

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.

The high-pressure pump 21 pressurizes the LNG stored in the fuel tank 20 while it is in a liquid state, and supplies the LNG to the vaporizer 22 .

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

Here, the liquefied fuel gas, which is in a liquid state within the fuel tank 20, is vaporized within the fuel tank 20 by natural heat input from the outside. As a result, boil off gas (BOG) is generated in the fuel tank 20 . When BOG occurs, the internal pressure of the fuel tank 20 rises. Therefore, to protect the fuel tank 20, the BOG needs to be treated. This BOG is preferably not simply incinerated, but effectively utilized as energy generated by the ship. BOG is supplied to the compressor 25 through the first BOG line LB1.

The compressor 25 compresses the BOG supplied from the fuel tank 20 to raise the pressure.

The generator 26 generates power using the BOG compressed by the compressor 25 . The generator 26 may be, for example, a generator driven by a gas-fired engine, and generates electric power using power obtained by burning the supplied BOG. The power generated by generator 26 is supplied to onboard loads that require power.

The steam generator 30 includes an exhaust gas economizer 31 and a boiler 32 .

The exhaust gas economizer 31 is a steam generator that uses exhaust gas to generate steam. The exhaust gas economizer 31 recovers heat from the exhaust gas E1 from the internal combustion engine 11 to generate steam S1. More specifically, the exhaust gas economizer 31 generates steam S1 by exchanging heat between the exhaust gas E1 supplied through the exhaust gas line LE1 and water. The exhaust gas E1 whose temperature has been lowered after being heat-exchanged by the exhaust gas economizer 31 is supplied to the second evaporator 41B of the binary generator 40, which will be described later.

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

The second BOG line LB2 is a free flow line through which BOG that has not been compressed by the compressor is supplied to the boiler 32 . That is, the second BOG line LB<b>2 is a line for releasing the pressure inside the fuel tank 20 that has increased due to the generation of BOG, and is connected to the boiler 32 . The boiler 32 burns the BOG supplied through the second BOG line LB2 to generate steam S2. This makes it possible to effectively utilize the BOG as energy generated in the ship.

It should be noted that surplus BOG may be supplied to the boiler 32 in situations such as when the amount of power generated by the generator 26 is sufficient. For example, the valve 27 provided in the first BOG line LB<b>1 may control the supply destination of the BOG compressed by the compressor 25 and all or part of the BOG may be supplied to the boiler 32 . Thereby, the boiler 32 can generate more steam S2. In this way, the BOG as energy generated in the ship can be appropriately distributed and effectively utilized according to the required amount of electric power and the required amount of steam.

Steam header 33 is connected to exhaust gas economizer 31 via steam line LS1. Also, the steam header 33 is connected to the boiler 32 via a steam line LS2. In the steam header 33, the steam S1 generated by the exhaust gas economizer 31 and the steam S2 generated by the boiler 32 gather. For example, the steam S1 and the steam S2 are gathered in the steam header 33, and the steam S3, which is the combined steam of these steams, is supplied to the steam expander generator 50 and the like, which will be described later.

The binary power generator 40 is a power generator that recovers thermal energy through the circulating working medium R1 and uses the expansion of the working medium R1 to generate power. More specifically, the binary power generator 40 of this embodiment heats and evaporates the working medium R1, which is a high-molecular-weight organic working medium with a low boiling point, with the heat source fluid, and the steam rotates the turbine to generate power. , an organic Rankine cycle (ORC) generator. In the ORC, evaporation and condensation of the working medium R1 are repeated.

The binary generator 40 includes an evaporator 41 that heats and vaporizes a 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 feeds the working medium R1 from the condenser 43 to the evaporator 41, the evaporator 41, the expander 42, the condenser 43, and and a working medium line LR1 through which the working medium R1 that flows through the circulation pump 44 circulates. Here, a generator 45 is connected to the expander 42 . The generator 45 generates electric power as the expander 42 rotates.

The evaporator 41 includes a first evaporator 41A and a second evaporator 41B.

The first evaporator 41A heats the working medium R1 by heat exchange between the supercharged air A1 from the supercharger 12 and the working medium R1. Supercharged air A1 is supplied to the first evaporator 41A through an air line LA1.

The second evaporator 41B heats the working medium R1 by 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 being heat-exchanged by the exhaust gas economizer 31 .

The expander 42 generates power using the working medium R1 heated and vaporized by the first evaporator 41A and the second evaporator 41B as a power source. The expander 42 of this embodiment is a screw type expander. The screw rotor is rotated by the heated and vaporized high-pressure working medium R1, and the generator 45 generates electric power accordingly. Note that the expander 42 is not limited to the screw type. For example, it may be a scroll type or a turbine type.

The condenser 43 cools and condenses the low pressure working medium R1 from the expander 42 . The condenser 43 exchanges heat between the coolant W1 sent through the coolant line LW1 and the working medium R1 to cool the working medium R1. As the coolant W1, for example, seawater or cooling water in the ship may be used. In the latter case, a cooler (not shown) that cools fresh water with sea water may be used.

The circulation pump 44 feeds the working medium R1 from the condenser 43 to the evaporator 41 .

As the working medium R1 circulating in the working medium line LR1, a polymer organic compound having a boiling point lower than that of water is used. The working medium R1 may be a flon-based medium such as HFC-245fa (chemical name: 1,1,1,3,3-pentafluoropropane, boiling point at 1 atmosphere: 15.3° C.). In addition, a non-fluorocarbon medium such as isopentane (boiling point at 1 atmosphere: 27.8° C.) or pentane (boiling point at 1 atmosphere: 36.1° C.) may be used. Furthermore, a natural medium such as 25% aqueous ammonia (boiling point at 1 atm: 38° C.) may be used instead of the polymer organic compound.

The ORC of the binary generator 40 in the present embodiment is, for example, when the saturated steam pressure at the inlet of the expander 42 is 2 MPa and seawater of about 25 to 30° C. is used as the cooling water W1, the outlet of the condenser 43 is It is designed to have a saturated steam pressure of 0.2 to 0.3 MPa. When HFC-245fa is used as the working medium R1, the outlet temperature of the condenser 43 is approximately in the range of 30 to 40.degree.

The supply flow rate of each fluid as a heat source fluid that exchanges heat with the working medium R1 may be adjusted by controlling a flow rate adjusting mechanism such as a valve (not shown). For example, a sensor that detects the temperature and pressure of the working medium R1 may be provided at the outlet of the evaporator 41 and the condenser 43, and the flow rate of the heat source fluid may be adjusted based on the detection result of the sensor.

Next, the power generation system 1 of this embodiment will be described. The power generation system 1 includes a steam expander generator 50 that converts the expansion of steam generated by the steam generator 30 into rotational force to generate power, and the steam that has been used by the steam expander generator 50 to generate power as a heat source fluid. and a steam binary generator 60 that performs

The steam expander power generator 50 is a power generator that converts expansion of steam into rotational force to generate power. The steam expander generator 50 may have, for example, a twin-screw expansion mechanism. In this case, the steam expander generator 50 is configured by 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. A pair of screw rotors arranged in a rotor casing (not shown) rotates. This rotational power is transmitted to the generator shaft to generate electric power.

The steam expander generator 50 basically does not recover thermal energy from the steam S3, but recovers the pressure energy of the steam S3 to generate electric power. Therefore, the steam S4 discharged from the steam expander power generator 50 has a lower pressure than the steam S3 flowing into the steam expander power generator 50, and has a saturated steam temperature corresponding to the pressure after the pressure drop. The steam S3 that has flowed into the intake port of the steam expander generator 50 becomes decompressed steam S4, is discharged from the exhaust port of the steam expander generator 50, and is supplied to the steam binary generator 60. Thus, the steam expander generator 50 also functions as a decompression device.

The steam expander power generator 50 generates power using steam S1 generated by the exhaust gas economizer 31 and steam S2 generated by the boiler 32, for example. However, the steam to be used is not limited to this.

The steam binary power generator 60 is a binary power generator that recovers thermal energy from steam as a heat source fluid via a circulating working medium R2 and generates power based on expansion of the working medium R2. More specifically, the steam binary power generator 60 of the present embodiment heats and vaporizes the working medium R2, which is a high-molecular-weight organic working medium with a low boiling point, with steam as a heat source fluid, and the working fluid generated by the vaporization It is an organic Rankine cycle (ORC) generator that rotates a screw rotor with the steam of medium R2 to generate power. The steam binary power generator 60 of the present embodiment generates power using the decompressed steam S4 after being used in the steam expander power generator 50 as a heat source fluid.

The steam binary generator 60 includes an evaporator 61 that heats and vaporizes a working medium R2 using steam S4, and 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 feeds the working medium R2 from the condenser 63 to the evaporator 61, the evaporator 61, the expander 62, the condenser 63, and a working medium line LR2 through which the working medium R2 flowing through the circulation pump 64 circulates. Here, a generator 65 is connected to the expander 62 . The generator 65 generates electric power as the expander 62 rotates.

The evaporator 61 heats the working medium R2 by heat exchange between the decompressed steam S4 after use in the steam expander generator 50 and the working medium R2. Steam S4 is supplied to evaporator 61 through steam line LS4.

The expander 62 generates power using the working medium R2 heated and vaporized by the evaporator 61 as a power source. The expander 62 of this embodiment is a screw type expander. The screw rotor is rotated by the heated and vaporized high-pressure working medium R2, and the generator 65 generates electric power accordingly. Note that the expander 62 is not limited to the screw type. For example, it may be a scroll type or a turbine type.

The condenser 63 cools and condenses the low pressure working medium R2 from the expander 62 . The condenser 63 exchanges heat between the coolant W2 sent through the coolant line LW2 and the working medium R2 to cool the working medium R2. As the coolant W2, for example, seawater or cooling water in the ship may be used. In this embodiment, a cooler 71 that cools the coolant W2 with seawater is provided, and the cooler 71 circulates the coolant W2 with the condenser 63 .

A circulation pump 64 feeds the working medium R2 from the condenser 63 to the evaporator 61 .

As the working medium R2 circulating in the working medium line LR2, a polymeric organic working medium having a boiling point lower than that of water is used. The working medium R2 may be, for example, a Freon-based medium such as HFC-245fa. However, the working medium R2 is not limited to this. For example, isopentane, pentane, or 25% aqueous ammonia may be used.

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

Steam generated by the steam generator 30 is supplied to the steam expander generator 50 and the steam binary generator 60 via the steam header 33 .

Here, the steam expander generator 50 may use the steam S1 generated by the exhaust gas economizer 31 or the steam S2 generated by the boiler 32 as the steam for obtaining power. Also, as shown in this embodiment, steam S3, which includes steam S1 and steam S2, may be used.

Note that the steam used in the steam expander generator 50 is not limited to this, as long as it is steam generated in a ship. For example, the steam used in the steam expander generator 50 may be steam generated by an auxiliary boiler (not shown). The fuel of the auxiliary boiler may be gas fuel or oil fuel.

Part of the steam S1 generated by the exhaust gas economizer 31 and the steam S2 generated by the boiler 32 is supplied to the steam expander generator 50 through the steam line LS3C, and part of the steam is supplied to the ship through the steam line LS3B. It may be supplied to a demand destination D (heating of fuel oil or lubricating oil, heating of air conditioning, etc.). The amount of steam supplied to each supply destination is adjusted by a valve 36, a valve 35, or the like as supply amount adjusting means.

The steam line may 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.

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 the present embodiment, the internal combustion engine 11, and the like so that the energy generated in the ship can be effectively utilized. For example, the control unit 100 may control valves and the like provided in each line based on detection results of sensors attached to each unit.

Next, the flow of each fluid flowing through each line will be described.

First, the flow of LNG as liquefied fuel gas will be described. LNG flowing through the fuel line LF1 is supplied from the fuel tank 20 and flows through the high-pressure pump 21, the carburetor 22, and the internal combustion engine 11 in this order. A fuel line LF1 is a line that connects the fuel tank 20, the high-pressure pump 21, the carburetor 22 and the internal combustion engine 11 together.

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

Next, the flow of air A1 will be described. Air A1 flowing through air line LA1 is compressed by supercharger 12 and flows through first evaporator 41A, intercooler 13, and internal combustion engine 11 in this order. Air line LA<b>1 is a line that connects supercharger 12 , first evaporator 41</b>A, intercooler 13 and internal combustion engine 11 .

The air A1 taken into the supercharger 12 is compressed and supplied to the first evaporator 41A as supercharged air A1. The supercharged air A1, which has been compressed to a high temperature, exchanges heat with the working medium R1 in the first evaporator 41A to heat the working medium R1. The supercharged air A<b>1 whose temperature has been lowered by heat exchange is further cooled to a predetermined temperature in the intercooler 13 and sent to the internal combustion engine 11 .

The temperature of the supercharged air A1 flowing into the first evaporator 41A may be, for example, 50° C. or higher and 250° C. or lower, and the temperature of the supercharged air A1 sent into the internal combustion engine 11 may be, for example, 40° C. or higher and 50° C. or higher. °C or lower. The temperature of the supercharged air A1 flowing into the first evaporator 41A may be about 150° C., for example.

Note that if the supercharged air A1 is supplied to the internal combustion engine 11 at a high temperature, the heat load of the internal combustion engine 11 increases. Also, the amount of charged air is reduced, and the output is also reduced. 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 first used as the heat source fluid of the first evaporator 41A without immediately being exhausted by the intercooler 13. there is Thus, by recovering the heat of compression of the supercharged air A1 by the first evaporator 41A, the energy generated in the ship can be effectively utilized.

Next, the flow of exhaust gas E1 will be described. The exhaust gas E1 flowing through the exhaust gas line LE1 is discharged from the internal combustion engine 11 and flows through the exhaust turbine, which is the driving source of the supercharger 12, the exhaust gas economizer 31, and the second evaporator 41B in this order. The exhaust gas line LE1 is a line that connects the internal combustion engine 11, the turbocharger 12, the exhaust gas economizer 31, and the second evaporator 41B.

Exhaust gas E1 discharged from the internal combustion engine 11 drives an exhaust turbine in the supercharger 12 . The exhaust gas E1 is supplied to the exhaust gas economizer 31 in a state in which the exhaust pressure is recovered by being used as a driving force for the exhaust turbine. The exhaust gas E1 exchanges heat with water in the exhaust gas economizer 31 to generate steam S1. The exhaust gas E1 whose temperature has been lowered by heat exchange in the exhaust gas economizer 31 is supplied to the second evaporator 41B. The exhaust gas E1 exchanges heat with the working medium R1 to heat the working medium R1. The exhaust gas E1 whose temperature has been further lowered by performing heat exchange in the second evaporator 41B is discharged from the second evaporator 41B.

The temperature of the exhaust gas E1 flowing into the exhaust gas economizer 31 may be, for example, 180° C. or higher and 400° C. or lower, and the temperature of the exhaust gas E1 flowing into the second evaporator 41B may be, for example, 150° C. or higher and 300° C. or lower. may The temperature of the exhaust gas E1 flowing into the second evaporator 41B may be, for example, about 170°C.

When the internal combustion engine 11 is operated, exhaust gas E1 is generated. As shown in this embodiment, while the exhaust pressure of the exhaust gas E1 is recovered by driving the supercharger 12, the exhaust heat of the exhaust gas E1 is primarily recovered by the exhaust gas economizer 31, and further recovered secondarily by the second evaporator 41B. By doing so, the energy generated in the ship can be efficiently and effectively utilized.

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

The BOG flowing through the first BOG line LB<b>1 is compressed by the compressor 25 to a pressure required by the generator 26 and supplied to the generator 26 . The BOG is combusted in generator 26 to produce electrical power.

BOG flowing through the first BOG line LB1 is also supplied to the boiler 32 by controlling the valve 27 . Also, the BOG generated in the fuel tank 20 is supplied to the boiler 32 through the second BOG line LB2. BOG is combusted in a boiler to produce steam S2.

Next, the flow of steam S1, steam S2, steam S3, and steam S4 will be described.

The 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. Steam S1 and steam S2 collected in the steam header are supplied as steam S3 to steam expander generator 50 through steam line LS3C. In addition, the steam S3 is supplied to the steam demand destination D on the ship through the steam line LS3B. The supply amount of the steam S3 to each supply destination is adjusted by a valve 36, a valve 35, etc. as supply amount adjustment means.

The steam S3 is pressure-recovered by the steam expander generator 50 and supplied to the steam binary generator 60 through the steam line LS4 as decompressed steam S4.

Note that the steam S3 may be supplied to the steam binary power generator 60 through the steam line LS3D when power generation by the steam expander power generator 50 is unnecessary. In this case, the steam S3 is decompressed by the decompression valve 37 and supplied to the steam binary generator 60 as decompressed steam S4.

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, the pressure P3 is 0.4 MPa or more and 0.95 MPa or less, and the pressure P4 is 0.1 MPa or more and 0.35 MPa or less. Note that 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, the temperature T3 is 152° C. or higher and 182° C. or lower, and the temperature T4 is 100° C. or higher and 148° C. or lower. However, the drop in temperature of the steam 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 .

Next, the flow of the working medium R1 of the binary generator 40 will be explained. The working medium R1 circulates through a working medium line LR1 that connects the evaporator 41, the expander 42, the condenser 43, and the circulation pump 44.

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 to drive the generator 45 . The low-pressure working medium R1 that has passed through the turbine of the expander 42 is cooled by the condenser 43 and condensed. The condensed working medium R1 is sent again to the evaporator 41 by the circulation pump 44 . Thus, the working medium R1 repeats evaporation and condensation while circulating through the working medium line LR1.

In this embodiment, as described above, the evaporator 41 has the first evaporator 41A and the second evaporator 41B. Therefore, the working medium R1 flows through the first evaporator 41A and the second evaporator 41B in this order. The working medium R1 undergoes heat exchange with the supercharged air A1 in the first evaporator 41A, and its temperature rises. The working medium R1 undergoes heat exchange with the exhaust gas E1 in the second evaporator 41B, and its temperature further rises. By providing a plurality of evaporators in this manner, a plurality of different heat source fluids generated in the ship can be effectively used as energy to heat the working medium R1 in stages.

The temperature of the working medium R1 flowing out of the second evaporator 41B may be, for example, about 120.degree. C., and the temperature of the working medium R1 flowing out of the condenser 43 may be, for example, about 40.degree.

Next, the flow of the working medium R2 in the steam binary generator 60 will be described. The working medium R2 circulates through a working medium line LR2 that connects the evaporator 61, the expander 62, the condenser 63, and the circulation pump 64.

The working medium R2 is heated by the steam S4 in the evaporator 61 and vaporized. The vaporized high-pressure working medium R2 drives the screw rotor of the expander 62 to generate electric power. The low-pressure working medium R2 that has passed through the screw rotor of the expander 62 is cooled by the condenser 63 and condensed. The condensed working medium R2 is re-fed to the evaporator 61 by the circulation pump 64 . Thus, the working medium R2 repeats evaporation and condensation while circulating through the working medium line LR2.

<Modification>
Since unused thermal energy often remains in the steam S3 after being used at the demand destination D, it is desirable to make effective use of this thermal energy. Specifically, the steam S3 after use at the demand destination D is collected and reused as the heat source fluid of the binary generator (binary generator 40 or steam binary generator 60). If the binary generator 40 recycles the steam S3, a third evaporator is added to the ORC through which the working medium R1 circulates. The third evaporator is connected between the second evaporator 41B and the expander 42, for example. Further, when the steam S3 is reused in the steam binary generator 60, a second evaporator is added to the ORC through which the second working medium circulates. The second evaporator is connected between the evaporator 61 and the expander 62, for example. The steam S3 after being used as a heat source fluid is recovered as condensed drain by cooling with seawater in a condenser. This condensed drain can be reused as feed water for the exhaust gas economizer 31 and the boiler 32 .

According to the marine power generation system 1 of this embodiment described above, the following effects can be obtained.

(1) The marine power generation system 1 of the present embodiment is a marine power generation system 1 that is used in a ship that includes a steam generator 30, and converts expansion of steam generated by the steam generator 30 into rotational force. and a steam binary generator 60 that generates power using the steam used by the steam expander generator 50 as a heat source fluid. Accordingly, it is possible to provide the ship power generation system 1 that can effectively utilize the energy generated in the ship.

In this way, by performing the steam cascade type power generation using the steam expander power generator 50 and the steam binary power generator 60, the steam generated in the ship can be effectively utilized. In the steam binary generator 60, the steam that exchanges heat with the working medium R2 may be low-pressure steam. On the other hand, the steam used in the steam expander generator 50 is required to have a medium pressure or higher. Therefore, the steam expander power generator 50 generates power using the steam of intermediate pressure or higher pressure generated in the ship, and then the steam binary power generator 60 is used in the steam expander power generator 50. By generating power using the depressurized steam, the steam generated in the ship can be effectively used and power can be generated efficiently.

(2) The steam binary power generator 60 of the present embodiment has an evaporator 61 that heats the working medium R2 by heat exchange between the steam S4 and the working medium R2 that have been used in the steam expander power generator 50 . Thereby, heat exchange between the steam S4 after being used in the steam expander power generator 50 and the working medium R2 circulating in the steam binary power generator 60 is properly performed.

(3) The steam generator 30 of the present embodiment includes a boiler 32 that generates steam S2 using the boil-off gas of the liquefied fuel gas as fuel, and the steam expander generator 50 expands the steam generated by the boiler 32. The steam binary generator 60 generates power by using the steam S4 used by the steam expander generator 50 as a heat source fluid. Thus, using the steam S2 generated by the boiler 32 that uses the boil-off gas of the liquefied fuel gas used in the internal combustion engine 11 as fuel, power generation is performed by the steam expander power generator 50 and power generation by the steam binary power generator 60. Therefore, the energy generated by the ship is used more effectively.

(4) The steam generator 30 of the present embodiment includes an exhaust gas economizer 31 that generates steam S1 using exhaust gas E1 from the ship's internal combustion engine 11, and the steam expander generator 50 is generated by the exhaust gas economizer 31. The steam binary power generator 60 generates power by using the steam S4 used by the steam expander power generator 50 as a heat source fluid. Using the steam S1 generated by the exhaust gas economizer 31 that uses the exhaust gas E1 from the internal combustion engine 11 in this way, the steam expander generator 50 and the steam binary generator 60 generate power. The energy generated is used more effectively.

Although preferred embodiments of the marine power generation system of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be modified as appropriate.

S ship 1 ship power generation system 11 internal combustion engine (main engine)
12 Turbocharger 13 Intercooler 20 Fuel Tank 30 Steam Generator 31 Exhaust Gas Economizer 32 Boiler 40 Binary Generator 50 Steam Expander Generator 60 Steam Binary Generator 61 Evaporator 62 Expander 63 Condenser 64 Circulation Pump 65 Generator R1 , R2 refrigerant A1 air, supercharged air (compressed air)
E1 Exhaust gas LNG Liquefied natural gas S1, S2, S3, S4 Steam

Claims (4)

A marine power generation system for use in a ship equipped with a steam generator,
a steam expander generator that converts the expansion of the steam generated by the steam generator into rotational force to generate power;
and a steam binary power generator that generates power using the steam used by the steam expander power generator as a heat source fluid. 2. The marine power generation system of claim 1, wherein the steam binary generator comprises an evaporator that heats the working medium by heat exchange between the steam and the working medium after use in the steam expander generator. The steam generating unit includes a boiler that generates steam using the boil-off gas of the liquefied fuel gas as fuel,
The steam expander generator converts expansion of steam generated in the boiler into rotational force to generate power,
3. The marine power generation system according to claim 1, wherein said steam binary power generator generates power using steam used by said steam expander power generator as a heat source fluid. The steam generator includes an exhaust gas economizer that generates steam using exhaust gas from an internal combustion engine of the ship,
The steam expander generator converts the expansion of the steam generated by the exhaust gas economizer into rotational force to generate power,
3. The marine power generation system according to claim 1, wherein said steam binary power generator generates power using steam used by said steam expander power generator as a heat source fluid.

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