JP7806483B2 - Marine Power Generation Systems - Google Patents

Description

The present invention relates to a marine power generation system.

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

Japanese Unexamined Patent Publication No. 55-25590

In the marine power generation system described in Patent Document 1, steam generated in a waste heat boiler is used to rotate a steam turbine, generating electricity. However, the marine power generation system described in Patent Document 1 cannot be said to fully utilize the energy generated on the ship.

The present invention aims to provide a marine power generation system that can effectively utilize the energy generated on board the ship.

The present invention relates to a marine power generation system (e.g., marine power generation system 1) used in a marine vessel (e.g., marine vessel S) including an internal combustion engine (e.g., internal combustion engine 11) fueled by liquefied fuel gas, 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, and a boiler (e.g., boiler 32) that generates steam ( e.g., steam S2) using boil-off gas of the liquefied fuel gas as fuel, the marine power generation system including a steam expander generator (e.g., steam expander generator 50) that converts the expansion of the steam into rotational force to generate power, and a steam boiler that generates power using the steam as a heat source fluid. the steam header (e.g., steam header 33) that collects steam generated in the exhaust gas economizer and steam generated in the boiler and is capable of supplying steam to each of a steam demand destination (e.g., demand destination D) in the ship and the steam expander generator, and the steam binary generator generates power while being supplied with steam (e.g., steam S4) used in the steam expander generator .

It is also preferable that the steam header is capable of supplying steam to the steam binary generator, and that the steam binary generator generates electricity in either a first power generation state in which steam used in the steam expander generator is supplied, or a second power generation state in which steam is supplied from the steam header without passing through the steam expander generator .

It is also preferable to provide a supply amount adjustment means (e.g., valves 35 and 36) that adjusts the amount of steam supplied from the steam header to the demand destination and the steam expander generator, and a control unit (e.g., control unit 100) that controls the supply amount adjustment means .

Preferably, the second binary generator is configured to generate electricity using supercharged air (for example, supercharged air A1) supplied to the internal combustion engine as a heat source fluid in addition to exhaust gas from the internal combustion engine .

The present invention provides a marine power generation system that can effectively utilize the energy generated on board a ship.

1 is a schematic diagram showing a marine power generation system according to an embodiment of the present invention;

A marine power generation system 1 according to an embodiment of the present invention will be described below with reference to the drawings. Note that in this specification, the term "line" is a general term for a line, such as a flow path, a pathway, or a conduit, through which a fluid can flow.

Figure 1 is a schematic diagram showing a ship S equipped with a ship power generation system 1 according to this embodiment. The ship power generation system 1 according to this embodiment is a power generation system 1 used on a ship S having a steam generating unit 30. Here, the ship S equipped with the power generation system 1 according to this embodiment includes an internal combustion engine 11, a turbocharger 12, an intercooler 13, a fuel tank 20, a high-pressure pump 21, a carburetor 22, a compressor 25, a generator 26, a steam generating unit 30, a steam header 33, and a binary generator 40.

The internal combustion engine 11 is, for example, a main engine that generates power to propel a ship. In this embodiment, the internal combustion engine 11 is a well-known diesel engine in which a cylinder is held in a main engine box (not shown) and a piston is fitted into the cylinder so that it can move back and forth. The internal combustion engine 11 draws supercharged air A1 (compressed air A1) sent from an air line LA1 into the cylinder and compresses it with the piston, and then injects fuel into the pressurized air, causing it to explode and burn, driving the piston and generating rotational power. When the internal combustion engine 11 is operating, 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. The liquefied fuel gas is supplied from a fuel tank 20 (described below) through a fuel line LF1. Examples of liquefied fuel gas that can be used include liquefied natural gas (LNG), liquefied petroleum gas (LPG), and ammonia. In this embodiment, LNG is used.

The supercharger 12 is an exhaust turbine turbocharger that sends supercharged air A1 to the internal combustion engine 11. The supercharger 12 takes in air A1 using the rotational force of the exhaust turbine, which is rotated by the flow of exhaust gas E1 emitted from the internal combustion engine 11, and compresses the air A1. The compressed supercharged air A1 is sent to the internal combustion engine 11 through an air line LA1.

The intercooler 13 cools the supercharged air A1 sent to the internal combustion engine 11. The intercooler may be water-cooled or air-cooled. If the intercooler is water-cooled, 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 below) and then supplied to the intercooler 13 for further cooling.

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 still in liquid form and supplies it to the vaporizer 22.

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 and vaporizes the LNG using the heater. Note that 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 via the fuel line LF1.

Here, the liquefied fuel gas in liquid form inside the fuel tank 20 vaporizes inside the fuel tank 20 due to natural heat input from the outside. This generates boil-off gas (BOG) inside the fuel tank 20. When BOG is generated, the internal pressure of the fuel tank 20 increases. Therefore, to protect the fuel tank 20, the BOG must be disposed of. It is preferable that this BOG is not simply incinerated, but is effectively utilized as energy generated on the ship. The BOG is supplied to the compressor 25 via the first BOG line LB1.

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

The generator 26 generates electricity using the 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 onboard loads that require power.

The steam generation unit 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 reduced 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.

The boiler 32 is a device that generates steam S2 using LNG BOG as liquefied fuel gas as fuel, and is, for example, a marine water-tube boiler. BOG generated in the fuel tank 20 is supplied to the boiler 32 via 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. In other words, the second BOG line LB2 is a line for releasing the pressure inside the fuel tank 20 that has increased due to the generation of BOG, and this line is connected to the boiler 32. The boiler 32 combusts the BOG supplied through the second BOG line LB2 to generate steam S2. This allows the BOG generated on the ship to be effectively utilized as energy.

In addition, 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, the destination of the BOG compressed by the compressor 25 may be controlled by a valve 27 provided on the first BOG line LB1, 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, the BOG generated on the ship as energy can be appropriately distributed and effectively utilized according to the required amount of electricity and steam.

The steam header 33 is connected to the exhaust gas economizer 31 via a steam line LS1. The steam header 33 is also connected to the boiler 32 via a steam line LS2. Within the steam header 33, steam S1 generated in the exhaust gas economizer 31 and steam S2 generated in 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, which will be described later, etc.

The binary generator 40 recovers thermal energy via the 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, a low-boiling-point high-molecular-weight organic working medium, using a heat source fluid, and using the resulting vapor to rotate a turbine. In an ORC, the working medium R1 repeatedly evaporates and condenses.

The binary generator 40 includes an evaporator 41 that uses a heat source fluid to heat and vaporize the working medium R1, 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 circulates through the evaporator 41, expander 42, condenser 43, and circulation pump 44. A generator 45 is connected to the expander 42. The generator 45 generates electricity as the expander 42 rotates.

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

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

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 uses the exhaust gas E1, whose temperature has been reduced after heat exchange in the exhaust gas economizer 31, to heat the working medium R1.

The expander 42 generates power using the working medium R1 heated and vaporized by the first evaporator 41A and second evaporator 41B as a power source. In this embodiment, the expander 42 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 electricity 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 working medium R1 and the coolant W1 sent through the coolant line LW1, thereby cooling the working medium R1. The coolant W1 may be, for example, seawater or shipboard cooling water. In the latter case, a cooler (not shown) that cools fresh water with seawater may be used.

The circulation pump 44 pumps the working medium R1 from the condenser 43 into the evaporator 41.

The working fluid R1 circulating through the working fluid line LR1 is a polymeric organic compound with a boiling point lower than that of water. 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 atmosphere: 15.3°C). Non-fluorocarbon-based mediums such as isopentane (boiling point at 1 atmosphere: 27.8°C) and pentane (boiling point at 1 atmosphere: 36.1°C) may also be used. Furthermore, instead of a polymeric organic compound, a natural medium such as 25% aqueous ammonia (boiling point at 1 atmosphere: 38°C) may also be used.

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

The supply flow rate of each fluid serving as a 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 that detect 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.

Next, the power generation system 1 of this embodiment will be described. The power generation system 1 includes a steam expander generator 50 that generates electricity by converting the expansion of steam generated by the steam generating unit 30 into rotational force, and a steam binary generator 60 that generates electricity using the steam used in the steam expander generator 50 as a heat source fluid.

The steam expander generator 50 is a generator that generates electricity by converting steam expansion into rotational force. The steam expander generator 50 may have, for example, a twin-screw expansion mechanism. In this case, the pressure difference 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 rotates a pair of screw rotors located within a rotor casing (not shown) that constitutes the steam expander generator 50. This rotational power is transmitted to the generator shaft, generating electricity.

This steam expander generator 50 does not generally recover thermal energy from the steam S3, but rather recovers the pressure energy of the steam S3 to generate electricity. 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 has a saturated steam temperature that corresponds 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.

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

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 of this embodiment is an organic Rankine cycle (ORC) type generator that generates electricity by heating and vaporizing the working medium R2, a low-boiling-point high-molecular-weight organic working medium, using steam as a heat source fluid, and then rotating a screw rotor with the vapor of the working medium R2 produced by the vaporization. The steam binary generator 60 of this embodiment generates electricity using decompressed steam S4 after use in the steam expander generator 50 as a heat source fluid.

The steam binary generator 60 includes an evaporator 61 that uses steam S4 to heat and vaporize the working medium R2, 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 circulates through the evaporator 61, expander 62, condenser 63, and circulation pump 64. A generator 65 is connected to the expander 62. The generator 65 generates electricity as the expander 62 rotates.

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

The expander 62 generates power using the working medium R2 heated and vaporized by the evaporator 61 as its power source. In this embodiment, the expander 62 is a screw-type expander. The screw rotor is rotated by the heated and vaporized high-pressure working medium R2, which in turn causes the generator 65 to generate electricity. Note that the expander 62 is not limited to a 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 working medium R2 and the cooling liquid W2 sent through the cooling liquid line LW2, thereby cooling the working medium R2. The cooling liquid W2 may be, for example, seawater or onboard cooling water. In this embodiment, a cooler 71 is provided that cools the cooling liquid W2 using seawater, and this cooler 71 circulates the cooling liquid W2 between the condenser 63 and the cooler 71.

The circulation pump 64 pumps the working medium R2 from the condenser 63 into the evaporator 61.

The working medium R2 circulating through the working medium line LR2 is a high-molecular-weight organic working medium with a boiling point lower than that of water. The working medium R2 may be, for example, a fluorocarbon-based medium such as HFC-245fa. However, the working medium R2 is not limited to this. For example, it may be isopentane, pentane, or 25% aqueous ammonia.

The supply flow rates of the steam S4 and coolant W2, which 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 that detect 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.

Steam generated by the steam generating unit 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 steam S1 generated by the exhaust gas economizer 31 or steam S2 generated by the boiler 32 as steam to generate power. Furthermore, as shown in this embodiment, steam S3 containing steam S1 and steam S2 may also be used.

However, the steam used in the steam expander generator 50 is not limited to this, and can be steam generated on the ship. 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 gas fuel or oil fuel.

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

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

The power generation system 1 of this embodiment is equipped with 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 as to effectively utilize the energy generated on the ship. The control unit 100 may, for example, control valves and the like installed on each line based on the detection results of sensors attached to each part.

Next, we will explain the flow of each fluid through each line.

First, we will explain the flow of LNG as liquefied fuel gas. LNG circulating through the fuel line LF1 is supplied from the fuel tank 20 and flows in this order through the high-pressure pump 21, the vaporizer 22, and the internal combustion engine 11. The fuel line LF1 is a line connecting the fuel tank 20, the high-pressure pump 21, the vaporizer 22, and the internal combustion engine 11.

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.

Next, the flow of air A1 will be explained. Air A1 flowing through the air line LA1 is compressed by the turbocharger 12 and flows through the first evaporator 41A, intercooler 13, and internal combustion engine 11 in that order. The air line LA1 is a line connecting the turbocharger 12, first evaporator 41A, intercooler 13, and internal combustion engine 11.

Air A1 taken in by the turbocharger 12 is compressed and supplied to the first evaporator 41A as supercharged air A1. The compressed, 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 been reduced by the 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 to the internal combustion engine 11 may be, for example, 40°C or higher and 50°C or lower. The temperature of the supercharged air A1 flowing into the first evaporator 41A may be, for example, approximately 150°C.

If the supercharged air A1 is supplied to the internal combustion engine 11 while still hot, the thermal load on the internal combustion engine 11 increases. Furthermore, the amount of charged air decreases, resulting in a decrease in output. 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 wasted in the intercooler 13, but is first used as a heat source fluid for the first evaporator 41A. In this way, by recovering the waste heat from the compression of the supercharged air A1 using the first evaporator 41A, the energy generated on the ship can be effectively utilized.

Next, the flow of exhaust gas E1 will be explained. Exhaust gas E1 flowing through the exhaust gas line LE1 is discharged from the internal combustion engine 11 and flows in the following order: the exhaust turbine that drives the turbocharger 12, the exhaust gas economizer 31, and the second evaporator 41B. The exhaust gas line LE1 is a line connecting the internal combustion engine 11, the turbocharger 12, the exhaust gas economizer 31, and the second evaporator 41B.

Exhaust gas E1 emitted from the internal combustion engine 11 drives the exhaust turbine in the turbocharger 12. The exhaust gas E1 is used to drive the exhaust turbine, recovering its exhaust pressure, and is then supplied to the exhaust gas economizer 31. 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 reduced by heat exchange in the exhaust gas economizer 31, is then supplied to the second evaporator 41B. The exhaust gas E1 exchanges heat with the working medium R1, heating the working medium R1. The exhaust gas E1, whose temperature has been further reduced by heat exchange in the second evaporator 41B, is then 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. The temperature of the exhaust gas E1 flowing into the second evaporator 41B may be, for example, around 170°C.

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, while the exhaust heat of the exhaust gas E1 is primarily 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 on the ship.

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 directly connects the fuel tank 20 and the boiler 32.

The BOG flowing through the first BOG line LB1 is compressed by the compressor 25 to the pressure required by the generator 26 and then supplied to the generator 26. The BOG is combusted in the generator 26, thereby generating electricity.

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

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

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

The steam S3 has its pressure recovered by the steam expander generator 50, and is supplied as reduced-pressure steam S4 to the steam binary generator 60 via steam line LS4.

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 via 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.

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 higher and 0.95 MPa or lower, and the pressure P4 is 0.1 MPa or higher and 0.35 MPa or lower. 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 decrease in the 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 by the steam binary generator 60.

Next, we will explain the flow of working medium R1 in the binary generator 40. 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, driving the generator 45. The low-pressure working medium R1 that passes through the turbine of the expander 42 is cooled and condensed in the condenser 43. The condensed working medium R1 is then pumped back into the evaporator 41 by the circulation pump 44. In this way, the working medium R1 repeatedly evaporates and condenses as it circulates through the working medium line LR1.

In this embodiment, as described above, the evaporator 41 has a first evaporator 41A and a second evaporator 41B. Therefore, the working medium R1 flows through the first evaporator 41A and then the second evaporator 41B. In the first evaporator 41A, the working medium R1 exchanges heat with the supercharged air A1, causing its temperature to rise. In the second evaporator 41B, the working medium R1 exchanges heat with the exhaust gas E1, causing its temperature to rise further. In this way, by providing multiple evaporators, it is possible to effectively use multiple different heat source fluids generated on the ship as energy and gradually heat the working medium R1.

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

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

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 passes through the screw rotor of the expander 62 is cooled and condensed in the condenser 63. The condensed working medium R2 is then pumped back into the evaporator 61 by the circulation pump 64. In this way, the working medium R2 repeatedly evaporates and condenses as it circulates through the working medium line LR2.

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

The marine power generation system 1 of this embodiment described above provides the following advantages:

(1) The marine vessel power generation system 1 of this embodiment is a marine vessel power generation system 1 used on a vessel equipped with a steam generating unit 30, and includes a steam expander generator 50 that generates electricity by converting the expansion of steam generated by the steam generating unit 30 into rotational force, and a steam binary generator 60 that generates electricity using steam used in the steam expander generator 50 as a heat source fluid. This makes it possible to provide a marine vessel power generation system 1 that can effectively utilize the energy generated on the vessel.

In this way, steam cascade power generation using the steam expander generator 50 and steam binary generator 60 allows for effective use of steam generated on board the ship. In the steam binary generator 60, the steam that exchanges heat with the working medium R2 can be low-pressure steam. On the other hand, the steam used in the steam expander generator 50 is required to be at medium pressure or higher. Therefore, the steam expander generator 50 generates power using steam at medium pressure or higher generated on board the ship, and then the steam binary generator 60 generates power using the reduced-pressure steam after use in the steam expander generator 50. This makes effective use of steam generated on board the ship and enables efficient power generation.

(2) The steam binary generator 60 of this embodiment has an evaporator 61 that heats the working medium R2 through heat exchange between the steam S4 after use in the steam expander generator 50 and the working medium R2. This allows for appropriate heat exchange between the steam S4 after use in the steam expander generator 50 and the working medium R2 circulating through the steam binary generator 60.

(3) In this embodiment, the steam generating unit 30 includes a boiler 32 that generates steam S2 using boil-off gas of liquefied fuel gas as fuel. The steam expander generator 50 generates electricity by converting the expansion of the steam generated in the boiler 32 into rotational force, and the steam binary generator 60 generates electricity using steam S4 used in the steam expander generator 50 as a heat source fluid. In this way, electricity is generated by the steam expander generator 50 and the steam binary generator 60 using steam S2 generated by the boiler 32 that uses boil-off gas of the liquefied fuel gas used in the internal combustion engine 11 as fuel, making more effective use of energy generated on the ship.

(4) In this embodiment, the steam generating unit 30 includes an exhaust gas economizer 31 that generates steam S1 using exhaust gas E1 from the ship's internal combustion engine 11. The steam expander generator 50 generates electricity by converting the expansion of the steam generated by the exhaust gas economizer 31 into rotational force, and the steam binary generator 60 generates electricity using steam S4 used by the steam expander generator 50 as a heat source fluid. In this way, electricity is generated by the steam expander generator 50 and the steam binary generator 60 using steam S1 generated by the exhaust gas economizer 31 that utilizes exhaust gas E1 from the internal combustion engine 11, making more effective use of energy generated on the ship.

The above describes a preferred embodiment of the marine power generation system of the present invention, but the present invention is not limited to the above embodiment 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 generating section 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, turbocharged air (compressed air)
E1 Exhaust gas LNG Liquefied natural gas S1, S2, S3, S4 Steam

Claims (4)

A marine power generation system for use on a marine vessel, the system comprising : an internal combustion engine fueled by liquefied fuel gas; an exhaust gas economizer that generates steam using exhaust gas from the internal combustion engine; and a boiler that generates steam using boil-off gas of the liquefied fuel gas as fuel ,
a steam expander generator that converts steam expansion into rotational force to generate electricity;
a steam binary generator that generates electricity using steam as a heat source fluid;
a second binary generator that generates electricity using exhaust gas from the internal combustion engine as a heat source fluid;
a steam header that collects steam generated by the exhaust gas economizer and steam generated by the boiler, the steam header being capable of supplying steam to each of a steam demand destination in the ship and the steam expander generator ,
the steam binary generator generates power in a state where steam used in the steam expander generator is supplied thereto;
Marine power generation systems. the steam header is capable of supplying steam to the steam binary generator;
2. The marine power generation system according to claim 1, wherein the steam binary generator generates power in either a first power generation state in which steam used in the steam expander generator is supplied, or a second power generation state in which steam is supplied from the steam header without passing through the steam expander generator. a supply amount adjusting means for adjusting the amount of steam supplied from the steam header to the demand destination and the steam expander generator;
3. The marine power generation system according to claim 1, further comprising: a control unit that controls the supply amount adjusting means . 3. The marine power generation system according to claim 1, wherein the second binary generator is configured to generate power using supercharged air to the internal combustion engine as a heat source fluid in addition to exhaust gas from the internal combustion engine .