JP7852238B2 - Ship power generation system - Google Patents

Description

This invention relates to a power generation system for ships.

Conventional shipboard power generation systems are known. For example, Patent Document 1 discloses a shipboard power generation system having an air cooler that preheats feedwater using air, and a waste heat boiler that vaporizes the preheated water using exhaust gas.

Japanese Unexamined Patent Publication No. 55-25590

In the shipboard power generation system described in Patent Document 1, electricity can be generated by rotating a steam turbine using steam produced in a waste heat boiler. However, the shipboard power generation system described in Reference Document 1 cannot be said to fully utilize the energy generated on the ship.

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

The present invention relates to a shipboard power generation system (e.g., shipboard power generation system 1) used in a ship, comprising: an internal combustion engine (e.g., internal combustion engine 11); an exhaust turbine type supercharger (e.g., supercharger 12) that supplies supercharged air (e.g., supercharged air A1) to the internal combustion engine; and 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 the system is a binary generator (e.g., binary generator) that recovers thermal energy via a circulating working medium (e.g., working medium R1) and generates electricity based on the expansion of the working medium. The present invention relates to a shipboard power generation system comprising 40), wherein the binary generator has a first evaporator (e.g., first evaporator 41A) that heats the working medium by heat exchange between supercharged air from the supercharger and the working medium, and a second evaporator (e.g., second evaporator 41B) that heats the working medium by heat exchange between exhaust gas from the internal combustion engine and the working medium, wherein the exhaust gas from the internal combustion engine flows in the order of exhaust turbine, which is the driving source of the supercharger, the exhaust gas economizer, and the second evaporator, and the heating of the working medium is carried out in the order of heating in the first evaporator and heating in the second evaporator .

Furthermore, the binary generator preferably further includes a third evaporator (for example, a third evaporator 41C), and the third evaporator heats the working medium by heat exchange between the steam generated in the exhaust gas economizer and the working medium.

Furthermore, the internal combustion engine uses liquefied fuel gas as fuel, the ship is equipped with a boiler (e.g., boiler 32) that generates steam (e.g., steam S2) using the boil-off gas of the liquefied fuel gas as fuel, the binary generator further has a third evaporator (e.g., third evaporator 41C), and the third evaporator preferably heats the working medium by heat exchange between the steam generated in the boiler and the working medium.

Furthermore, it is preferable to further include a steam expander generator (for example, a steam expander generator 50) that converts the expansion of steam into rotational force to generate electricity, and that the steam expander generator generates electricity using the steam produced by the exhaust gas economizer.

Furthermore, the internal combustion engine uses liquefied fuel gas as fuel, and the ship is equipped with a boiler (for example, boiler 32) that generates steam (steam S2) using the boil-off gas of the liquefied fuel gas as fuel, and a steam expander generator (for example, steam expander generator 50) that converts the expansion of the steam into rotational force to generate electricity, wherein the steam expander generator preferably generates electricity using the steam generated by the boiler.

Furthermore, it is preferable to have a steam binary generator (e.g., steam binary generator 60) that generates electricity using the steam (e.g., steam S4) remaining after use in the steam expander generator as a heat source fluid.

Furthermore, it is preferable that the steam binary generator has an evaporator (e.g., evaporator 61) that heats the working medium (e.g., working medium R2) circulating in the steam binary generator through heat exchange between the steam used in the steam expander generator and the working medium circulating in the steam binary generator.

According to the present invention, it is possible to provide a shipboard power generation system that can effectively utilize the energy generated on a ship.

This is a schematic diagram showing a shipboard power generation system according to the first embodiment of the present invention. This is a schematic diagram showing a shipboard power generation system according to a second embodiment of the present invention.

<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, "line" refers to a general term for lines through which fluids can flow, such as channels, routes, and pipelines.

Figure 1 is a schematic diagram showing a ship S equipped with the ship power generation system 1 of this embodiment. The ship power generation system 1 of this embodiment is a power generation system 1 used in 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 this 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.

The internal combustion engine 11 is, for example, the main engine used to propel a ship. The internal combustion engine 11 in this embodiment is a well-known diesel engine in which a cylinder is held within a main engine box (not shown), and a piston is fitted into the cylinder so as to be able to move back and forth. The internal combustion engine 11 draws in supercharged air A1 (compressed air A1) supplied from the air line LA1 into the cylinder, compresses it with the piston, and drives the piston to generate rotational power by injecting fuel into the high-pressure air and causing explosive combustion. When the internal combustion engine 11 is operated, exhaust gas E1 is generated. The exhaust gas E1 is discharged through the 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 the fuel tank 20 (described later) through the fuel line LF1. Examples of liquefied fuel gas that may 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 type turbocharger that supplies supercharged air A1 to the internal combustion engine 11. The supercharger 12 draws in air A1 using the rotational force of an exhaust turbine, which is rotated 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 then supplied to the internal combustion engine 11 through the air line LA1.

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) before being supplied to the intercooler 13 for further cooling.

The fuel tank 20 is a tank that stores liquefied fuel gas 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 remains 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. 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.

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. The generation of BOG increases the internal pressure of the fuel tank 20. Therefore, to protect the fuel tank 20, the BOG needs to be treated. Preferably, this BOG is not simply incinerated, but effectively utilized as energy generated by the ship. The BOG is supplied to the compressor 25 through 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 compressed BOG (boiled gas) from the compressor 25. The generator 26 may be, for example, a gas-fired engine-driven generator, and it 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 power. Note that the power generation system 1 of this embodiment may include this generator 26.

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.

The exhaust gas economizer 31 is a steam generator that produces steam using exhaust gas. 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, described later.

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 then rotating a turbine with the resulting vapor. In the ORC, the evaporation and condensation of the working medium R1 are repeated.

The binary generator 40 comprises 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 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 in conjunction with the rotation of the expander 42.

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

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.

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 decreased after heat exchange in the exhaust gas economizer 31, to heat the working medium R1.

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, for example, the steam S1 generated in the exhaust gas economizer 31 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.

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. In this embodiment, the expander 42 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 accordingly. Note that the expander 42 is not limited to a screw type. For example, it may be a scroll type or a turbine type.

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.

The circulation pump 44 sends the working fluid R1 from the condenser 43 to the evaporator 41.

Furthermore, a polymeric organic compound with a lower boiling point than water is used as the working medium R1 circulating in the working medium line LR1. The working medium 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.

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 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.

Furthermore, the supply flow rate of the heat source fluid that performs heat exchange 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.

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.

The boiler 32 is a device that generates steam S2 using BOG (bubble over gas) of LNG as fuel; for example, a marine water-tube boiler is used. 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 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 rises due to BOG generation, and this line is connected to the boiler 32. The boiler 32 burns the BOG supplied through the second BOG line LB2 to generate steam S2. This allows for the effective utilization of BOG as energy generated in the ship.

Furthermore, in situations where the power generation from 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.

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 combine within the steam header 33, and this combined steam, steam S3, is supplied to the third evaporator 41C, etc., via the steam line LS3A.

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.

Furthermore, 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.

Furthermore, 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 third evaporator 41C via steam line LS3A, and partially supplied to the steam demand destinations D on the ship (heating of fuel oil and lubricating oil, air conditioning heating, etc.) via 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.

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 and the internal combustion engine 11, etc., to effectively utilize the energy generated on the ship. For example, the control unit 100 may control valves, etc., provided in each line based on the detection results of sensors attached to each part.

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

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 connecting fuel tank 20, high-pressure pump 21, vaporizer 22, and 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 then supplied to the internal combustion engine 11.

Next, the flow of air A1 will be explained. Air A1 circulating 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.

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 before being sent to the internal combustion engine 11.

Furthermore, 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 also be, for example, around 150°C.

Furthermore, if the supercharged air A1 is supplied to the internal combustion engine 11 while still at a high temperature, the heat load on the internal combustion engine 11 will increase. Also, the amount of air supplied 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 waste heat in the intercooler 13, but is first used as a heat source fluid for the first evaporator 41A. By recovering the heat of compression of the supercharged air A1 as waste heat in the first evaporator 41A in this way, 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 exhaust gas line LE1 is discharged from the internal combustion engine 11 and flows in the following order: exhaust turbine (the drive source for the turbocharger 12), exhaust gas economizer 31, and second evaporator 41B. Exhaust gas line LE1 is the line connecting the internal combustion engine 11, turbocharger 12, exhaust gas economizer 31, and second evaporator 41B.

The exhaust gas E1 discharged from the internal combustion engine 11 drives the exhaust turbine in the turbocharger 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 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 further decreased due to heat exchange in the second evaporator 41B, is discharged from the second evaporator 41B.

Furthermore, 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 also be, for example, around 170°C.

When the internal combustion engine 11 is operated, exhaust gas E1 is generated. As shown in this embodiment, by recovering the exhaust pressure of the exhaust gas E1 by driving the turbocharger 12, first recovering the waste heat of the exhaust gas E1 with the exhaust gas economizer 31, and then secondarily recovering it with the second evaporator 41B, the energy generated in the ship can be efficiently and effectively utilized.

Next, the flow of BOG (Boiler Overgrowth) 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 then branches off 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 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.

The BOG flowing through the first BOG line LB1 is supplied to the boiler 32 through the control of valve 27. Furthermore, 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.

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

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 amount 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.

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.

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 then 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.

In this embodiment, as described above, the evaporator 41 comprises 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, causing its temperature to rise. In the second evaporator 41B, the working fluid R1 undergoes heat exchange with the exhaust gas E1, causing its temperature to rise further. In the third evaporator 41C, the working fluid R1 undergoes heat exchange with steam, causing its temperature to rise even 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.

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.

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

<Variation 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.

<Modified Example 2>
When seawater is used as the coolant W1 in the condenser 43 of the binary power generator 40, considering the high seawater temperature, the outlet temperature of the working fluid R1 in the condenser 43 is limited to about 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, thus increasing the amount of power generated. For example, lowering the outlet temperature of the working fluid R1 to about 10-20°C, or by 20°C, increases the amount of power generated by approximately 20-30%.

Therefore, it is preferable to install a supercooler to increase the heat dissipation of the working medium R1. Specifically, a supercooler is connected between the condenser 43 and the circulation pump 44, allowing heat exchange between the working medium R1 and the LNG supplied from the high-pressure pump 21. By utilizing the 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, etc., in the vaporizer 22 will be reduced compared to before the supercooler was installed.

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 further 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 used.

<Example 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.

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 by the boiler 32 is supplied to the third evaporator 41C to operate the binary generator 40. This allows for the effective utilization of energy generated on the ship.

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 under low-speed navigation.

<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.

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 allows for appropriate adjustment of the amount of steam generated by the exhaust gas economizer 31 and the amount of electricity generated by the binary generator 40.

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. Note that if the set temperature Ti is fixed, surplus steam may be generated due to fluctuations in the amount of steam used on board. In this case, the surplus steam may be introduced into the third evaporator 41C for heat recovery, thereby increasing the amount of electricity generated by the binary generator 40.

<Example 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 the working fluid R1 leaks due to corrosion of the second evaporator 41B, the binary generator 40 will become inoperable.

Therefore, it is preferable to implement corrosion countermeasures for 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, by increasing the rotation speed of the feedwater pump (not shown) to reduce the amount of heat absorbed by the feedwater, the system is operated so that the temperature of the exhaust gas E1 inside the exhaust gas economizer 31 does not fall below the acid dew point.

Furthermore, the exhaust gas temperature at the outlet 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 above the set temperature To2 (for example, 150°C). For example, by increasing the rotational speed of the circulation pump 44 to reduce the amount of heat absorbed by the working medium R1, the system is operated to ensure 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%.

The shipboard power generation system 1 of this embodiment, as described above, provides the following advantages.

(1) The ship power generation system 1 of this embodiment is a ship power generation system 1 used in a ship S equipped with an internal combustion engine 11 and an exhaust turbine type supercharger 12 that supplies supercharged air A1 to the internal combustion engine 11, and comprises an exhaust gas economizer 31 that generates steam S1 using exhaust gas E1 from the internal combustion engine 11, and a binary generator 40 that recovers thermal energy via a circulating working medium R1 and generates electricity based on the expansion of the working medium R1, wherein the binary generator 40 has a first evaporator 41A that 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 that 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. This makes it possible to effectively utilize the energy generated in the ship.

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. Furthermore, 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. This efficiently recovers the thermal energy of the supercharged air A1 and exhaust gas E1 in the binary generator 40. Moreover, 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 and before it flows into the second evaporator 41B, the energy generated on the ship can be effectively utilized.

In binary power generation, the working fluid typically used has 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.

(2) The binary generator 40 of the shipboard power generation system 1 of this embodiment further includes 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, the working medium R1 is heated in the third evaporator 41C 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. Therefore, the binary generator 40 recovers the energy generated on the ship more efficiently.

(3) The internal combustion engine 11 of the ship's power generation system 1 in 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 the liquefied fuel gas as fuel. The binary generator 40 further comprises a third evaporator 41C, which heats the working medium R1 through 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 through heat exchange between the steam S2 generated by the boiler 32, which uses BOG of the 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.

<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.

As shown in Figure 2, the shipboard power generation system 1 of this embodiment further comprises a steam expander generator 50 and a steam binary generator 60. The evaporator 41 of the binary generator 40 in this embodiment 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, similar to the first embodiment.

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, for example, have a twin-screw type expansion mechanism. In this case, the differential pressure between the steam supply pressure 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 within the rotor casing to rotate. This rotational power is transmitted to the generator shaft, generating electricity.

This steam expander generator 50 basically generates electricity by recovering the pressure energy of the steam S3, rather than recovering the 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 generator, 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. Thus, the steam expander generator 50 also functions as a pressure reducing device.

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 type of 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 fluid R2 and generates electricity based on the expansion of the working fluid 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 fluid R2, which is a low-boiling-point polymer organic working fluid, with steam as a heat source fluid, and then rotating a screw rotor with the vapor of the working fluid R2 produced by vaporization. In this embodiment, the steam binary generator 60 generates electricity using depressurized steam S4 after use in the steam expander generator 50 as the heat source fluid.

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 heated and vaporized working medium R2 from 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 in conjunction with the rotation of the expander 62.

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.

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, heated and vaporized, rotates the screw rotor, and the generator 65 generates electricity accordingly. 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 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. The coolant W2 may be, for example, seawater or the ship's cooling water. In this embodiment, a cooler 71 is provided to cool the coolant W2 with seawater, and this cooler 71 circulates the coolant W2 between itself and the condenser 63.

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

Furthermore, a polymeric organic compound with a lower boiling point than water is used as the working medium R1 circulating in the working medium line LR1. The working medium 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.

Furthermore, 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 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 sensor detection results.

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 combine within the steam header 33, and this combined steam, steam S3, is supplied to the steam expander generator 50, etc., via the steam line LS3C.

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 both steam S1 and steam S2 may be used.

Furthermore, 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 or oil-based.

Furthermore, 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 the steam line LS3C, and partially supplied to the steam demand destinations D on the ship (heating of fuel oil and lubricating oil, air conditioning heating, 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.

Furthermore, the steam line may 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 in the steam line LS3D.

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

The steam S1 generated by the exhaust gas economizer 31 is supplied to the steam header 33 via the steam line LS1. The steam S2 generated by the boiler 32 is supplied to the steam header 33 via the steam line LS2. The steam S1 and S2 collected in the steam header are supplied as steam S3 to the steam expander generator 50 via the steam line LS3C. Furthermore, steam S3 is supplied to the steam demand destinations D on the ship via 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.

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

Furthermore, in cases where power generation by the steam expander generator 50 is unnecessary, 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.

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. Also, 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 temperature decrease 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, 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.

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 then sent back to the evaporator 61 by the circulation pump 64. In this way, the working medium R2 repeatedly evaporates and condenses while circulating through the working medium line LR2.

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

<Modification 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.

In addition to the above-described effects (1) to (3), the shipboard power generation system 1 of this embodiment provides the following benefits.

(4) The shipboard power generation system 1 of this embodiment further includes a steam expander generator 50 that generates electricity by converting the expansion of steam into rotational force. 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.

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

(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 by the steam expander generator 50 as a heat source fluid. By performing power generation using a steam cascade system with the steam expander generator 50 and the steam binary generator 60 in this way, 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 or higher pressure. Therefore, by having the steam expander generator 50 generate electricity using steam at a medium or higher pressure generated on the ship, and then the steam binary generator 60 generating electricity using the reduced-pressure steam after use in the steam expander generator 50, the steam generated on the ship can be effectively utilized, and power generation can be performed efficiently.

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

The above describes preferred embodiments of the shipboard power generation system of the present invention. However, 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.

S Ship 1 Ship power generation system 11 Internal combustion engine (main engine)
12 Supercharger 13 Intercooler 20 Fuel Tank 31 Exhaust Gas Economizer 32 Boiler 40 Binary Generator 41 Evaporator 41A First Evaporator 41B Second Evaporator 41C Third Evaporator 42 Expander 43 Condenser 44 Circulation Pump 45 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, Supercharger Air (Compressed Air)
E1 Exhaust gas LNG Liquefied natural gas S1, S2, S3, S4 Steam

Claims (7)

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 . 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. 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's 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. 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. 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. 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. 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.