Cold ORC power generator and operation method of the same

Abstract

To provide a cold ORC power generator which can generate electric power efficiently even if a flow rate of a refrigerant serving as a cold source changes.SOLUTION: A cold ORC power generator 1 includes: an LNG vaporizer passage 12 which causes LNG to circulate to be vaporized; a condenser 3 which causes the LNG flowing in the LNG vaporizer passage 12 and a working fluid which is propane to exchange heat to heat and condense the working fluid; a liquid pump 5 which transports the working fluid condensed by the condenser 3; an evaporator 9 which causes the working fluid guided from the liquid pump 5 and sea water SW to exchange heat to evaporate the working fluid; a plurality of power generation turbines 11A, 11B which are driven by the working fluid guided from the evaporator 9 to generate electric power and arranged parallel to each other; and a control unit which controls the number of the operating power generation turbines 11A, 11B according to a heat exchange amount of the condenser 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a cold ORC power generation device and an operating method thereof. [Background technology]

[0002] A cold ORC (Organic Rankine Cycle) power generation system that uses a cold heat source such as LNG is known (for example, Patent Document 1). Such a cold ORC power generation system uses an organic fluid such as propane as a working fluid for performing the Rankine cycle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-542136 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Patent Document 1, one turbine is generally provided for one Rankine cycle. However, the amount of circulation of the working fluid varies depending on the flow rate of the refrigerant that serves as the cold heat source, and the operating point of the turbine varies accordingly. If the operating point of the turbine varies and deviates from the range in which the turbine can operate efficiently, the turbine efficiency deteriorates, which in turn reduces the power generation efficiency and, in some cases, the turbine cannot operate.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide a cold-heat ORC power generation device and an operating method thereof that can generate power efficiently even when the flow rate of the refrigerant that serves as the cold heat source fluctuates. [Means for solving the problem]

[0006] A cold-energy ORC power generation apparatus according to one embodiment of the present disclosure includes a refrigerant vaporization path through which a liquefied refrigerant is circulated to vaporize it, a condenser that exchanges heat between the liquefied refrigerant flowing through the refrigerant vaporization path and a working fluid that has been made into an organic fluid, heating the liquefied refrigerant and condensing the working fluid, a liquid pump that transports the working fluid condensed in the condenser, an evaporator that evaporates the working fluid guided from the liquid pump by heat exchange with a heat source, a plurality of power generation turbines that are driven by the working fluid guided from the evaporator to generate power and are arranged in parallel with each other, and a control unit that controls the number of power generation turbines in operation depending on the amount of heat exchange in the condenser.

[0007] A method for operating a cold-energy ORC power generation system according to one embodiment of the present disclosure includes a refrigerant vaporization flow path that circulates a liquefied refrigerant to vaporize it, a condenser that exchanges heat between the liquefied refrigerant flowing through the refrigerant vaporization flow path and a working fluid that has been made into an organic fluid to heat the liquefied refrigerant and condense the working fluid, a liquid pump that transports the working fluid condensed in the condenser, an evaporator that evaporates the working fluid guided from the liquid pump by heat exchange with a heat source, and a plurality of power generation turbines that are driven by the working fluid guided from the evaporator to generate power and are arranged in parallel with each other, and the number of power generation turbines in operation is controlled according to the amount of heat exchange in the condenser. Effect of the Invention

[0008] Even if the flow rate of the refrigerant that serves as the cold heat source fluctuates, power generation can be performed efficiently. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram illustrating a cold ORC power generation device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a vertical cross-sectional view of the power generating turbine of FIG. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 1 is a schematic diagram showing a configuration in which three power generating turbines are provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings. 1 shows a cold ORC (Organic Rankine Cycle) power generation system 1 according to this embodiment. The cold ORC power generation system 1 uses LNG (Liquefied Natural Gas) as a refrigerant that serves as a cold source. In addition to LNG, LPG (Liquefied Petroleum Gas), liquefied ammonia, etc. can be used as the refrigerant.

[0011] In the cold ORC power generation system 1 of this embodiment, propane (organic fluid) is used as the working fluid. Note that other organic fluids may be used as the working fluid, such as low molecular weight hydrocarbons such as isopentane and butane, and R134a and R245fa, which are used as refrigerants for air conditioners, etc.

[0012] The cold ORC power generation system 1 includes a condenser 3, a circulation pump (liquid pump) 5, an outlet valve (liquid pump outlet valve) 7, an evaporator 9, and a power generation turbine 11. The condenser 3, the circulation pump 5, the outlet valve 7, the evaporator 9, and the power generation turbine 11 are connected to a circulation path 13 through which propane, which is a working fluid, circulates.

[0013] The condenser 3 exchanges heat between LNG supplied through an LNG supply valve 15 passing through an LNG vaporization flow path (refrigerant vaporization flow path) 12 and propane supplied from the power generation turbine 11 through a circulation path 13. In the condenser 3, the LNG removes heat of condensation from the propane, condensing and liquefying the propane.

[0014] The condenser 3 is a plate type heat exchanger housed inside a pressure vessel. The plate type heat exchanger is made up of a plurality of stacked plates, e.g., disk-shaped plates, which are press-molded to form flow paths, and unlike a shell-and-tube heat exchanger, does not have a volume for storing liquefied fluid. For this reason, it has a more compact structure than a shell-and-tube heat exchanger, i.e., it has a larger heat transfer area per unit volume of equipment. The condenser 3 is constructed by housing the entire plate type heat exchanger in a vessel, e.g., a cylindrical vessel.

[0015] The LNG heated by absorbing heat from the propane in the condenser 3 is heated to a predetermined temperature by the trim heater 17 with seawater SW, and then is led to a supply destination as vaporized NG (natural gas).

[0016] The propane condensed and liquefied in the condenser 3 is guided to the drain tank 19. The drain tank 19 is a sealed container having a predetermined volume. A predetermined amount of liquefied propane is temporarily stored in the drain tank 19. Vaporized propane exists as a gas phase above the drain tank 19. A portion of the liquefied propane stored in the drain tank 19 is vaporized by heat that inevitably enters from the outside, and remains in the gas phase of the drain tank 19.

[0017] A pressure sensor 21 for detecting the pressure of the gas phase is provided on the upper part of the drain tank 19. The output of the pressure sensor 21 is transmitted to a control unit (not shown).

[0018] A circulation pump 5 is connected to the downstream side of the flow of liquefied propane in the drain tank 19. The circulation pump 5 supplies the liquefied propane temporarily stored in the drain tank 19 to the downstream side.

[0019] A mini-flow circulation flow path 28 equipped with a mini-flow valve 25 is provided downstream of the circulation pump 5. The mini-flow valve 25 is controlled by the control unit. The mini-flow circulation flow path 28 connects the outlet of the circulation pump 5 to the drain tank 19. By controlling the flow rate through the mini-flow circulation flow path 28, a minimum flow rate (mini-flow) through the circulation pump 5 is ensured. The circulation pump 5 is flow-controlled by the outlet valve 7 and the mini-flow valve.

[0020] The outlet valve 7 is provided downstream of the circulation pump 5, and controls the flow rate of the working fluid (liquefied propane) supplied to the evaporator 9. The outlet valve 7 is controlled by a control unit (not shown).

[0021] The evaporator 9 is provided downstream of the outlet valve 7, and evaporates and gasifies the liquefied propane by exchanging heat with seawater SW, which is a heat source. The evaporator 9 is a plate-type heat exchanger housed inside a pressure vessel. The plate-type heat exchanger is made up of a plurality of stacked plates, for example, disk-shaped plates, which are press-molded to form flow paths, and unlike the shell-and-tube heat exchanger, does not have a volume for storing liquefied fluid. For this reason, it has a more compact structure than the shell-and-tube heat exchanger. The evaporator 9 is constructed by housing the entire plate-type heat exchanger in a vessel, for example, cylindrical.

[0022] A superheat sensor 29 is provided on the outlet side of the evaporator 9 to obtain the degree of superheat of the vaporized propane. The output of the superheat sensor 29 is sent to the control unit. The superheat sensor 29 includes, for example, a temperature sensor and a pressure sensor. The control unit calculates the degree of superheat from the saturation temperature at the gas pressure obtained by the pressure sensor and the gas temperature obtained by the temperature sensor. The control unit controls the opening of the outlet valve 7 based on the degree of superheat obtained by using the superheat sensor 29.

[0023] A turbine flow rate control valve 31 is provided downstream of the superheat sensor 29. The turbine flow rate control valve 31 is controlled by the control unit based on the output of a pressure sensor 21 provided in the drain tank 19.

[0024] The power generation turbine 11 is provided downstream of the turbine flow rate control valve 31 via a turbine inlet valve 33. The opening degree of the turbine inlet valve 33 is controlled by the control unit. In this embodiment, two power generation turbines 11 are provided in parallel. Two power generation turbines 11 may be provided in parallel as in this embodiment, but three or more power generation turbines 11 may also be provided in parallel.

[0025] For example, as shown in Fig. 4, three power generation turbines, a first power generation turbine 11A, a second power generation turbine 11B, and a third power generation turbine 11C, may be provided in parallel. Fig. 4 shows a configuration in which the control unit PIC controls the opening degree of each turbine inlet valve 33A, 33B, and 33C based on the measurement value of a pressure sensor 21 that measures the internal pressure (pressure of the gas phase) of the drain tank 19 (see Fig. 1).

[0026] In this embodiment, one of the power generation turbines 11 is referred to as a first power generation turbine 11A, and the other is referred to as a second power generation turbine 11B. Additionally, the turbine inlet valve 33 corresponding to the first power generation turbine 11A is referred to as a first turbine inlet valve 33A, and the turbine inlet valve 33 corresponding to the second power generation turbine 11B is referred to as a second turbine inlet valve 33B. However, when there is no need to distinguish between them, they will simply be referred to as the power generation turbine 11 and the turbine inlet valve 33.

[0027] The power generation turbine 11 is rotated and generates power by a working fluid (vaporized propane) supplied via a turbine inlet valve 33. A specific configuration of the power generation turbine 11 will be described later.

[0028] A bypass path 35 is provided so as to bypass the turbine flow rate control valve 31, the turbine inlet valve 33, and the power generation turbine 11. The bypass path 35 is provided with a bypass flow rate control valve 37. The bypass flow rate control valve 37 is controlled by the control unit based on the output of a pressure sensor 21 provided in the drain tank 19.

[0029] The control unit is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads this program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, may be provided in a state stored in a computer-readable storage medium, or may be distributed via a wired or wireless communication means. The computer-readable storage medium may be a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

[0030] <Power generating turbine> The power generation turbines 11A, 11B described above are integrated power generation turbines in which a turbine section and a power generation section are integrated, and have the same configuration. Therefore, in the following, the power generation turbines 11A, 11B will be denoted by the reference numeral 11, and the common configuration will be described.

[0031] 2 shows a longitudinal section of the power generating turbine 11. FIG 3 shows a cross section taken along line AA of FIG 2.

[0032] Hereinafter, the upstream side in the flow direction of the working fluid in the power generation turbine 11 may be simply referred to as the upstream side, and the downstream side in the flow direction of the working fluid in the power generation turbine 11 may be simply referred to as the downstream side. Furthermore, the radial direction of the power generation turbine 11 may be simply referred to as the radial direction, and the circumferential direction of the power generation turbine 11 may be simply referred to as the circumferential direction. Furthermore, the direction along the axis CA of the power generation turbine 11 may be simply referred to as the axial direction.

[0033] 2, the power generation turbine 11 includes a rotor shaft 16, a casing 6, a generator 8, a first-stage axial turbine 23, a second-stage axial turbine 24, and a working fluid flow path 63. The first-stage axial turbine 23 is composed of a first-stage rotor blade 23B and a first-stage stator blade 23A. The second-stage axial turbine 24 is composed of a second-stage rotor blade 24B and a second-stage stator blade 24A.

[0034] The rotor shaft 16 includes a shaft portion 111 having a longitudinal direction along the axis CA of the power generation turbine 11, a one-side disk portion 113A protruding radially outward in a circular plate shape from an outer surface 112A on one side (upstream side) of the shaft portion 111, and an other-side disk portion 113B protruding radially outward in a circular plate shape from an outer surface 112B on the other side (downstream side) of the shaft portion 111.

[0035] The axis CA of the power generation turbine 11 coincides with the axis of the rotor shaft 16 and the axis of the casing 6 .

[0036] At one end of the shaft portion 111 in the axial direction, a one-side protruding portion 114A is formed, which protrudes outward in the axial direction from an inner casing member 61A described later. At the other end of the shaft portion 111 in the axial direction, a other-side protruding portion 114B is formed, which protrudes outward in the axial direction from the inner casing member 61A. The one-side protruding portion 114A and the other-side protruding portion 114B are formed to have a smaller diameter than other parts of the shaft portion 111. The one-side disk portion 113A described above is attached to the outer surface 112A of the one-side protruding portion 114A. Similarly, the other-side disk portion 113B described above is attached to the outer surface 112B of the other-side protruding portion 114B. At one side of the one-side disk portion 113A in the one-side protruding portion 114A, a one-side nut 115A is screwed, thereby fixing the one-side disk portion 113A to the shaft portion 111. Similarly, a second-side nut 115B is screwed onto the second-side protrusion 114B on the other side of the second-side disk portion 113B, thereby fixing the second-side disk portion 113B to the shaft portion 111.

[0037] The casing 6 is composed of an inner casing 61 that rotatably houses the rotor shaft 16 and an outer casing 62 that is disposed on the outer periphery of the inner casing 61 . The inner casing 61 includes an inner casing member 61A, a one-side cover member 61B arranged on one axial side (upstream side) of the inner casing member 61A, and an other-side cover member 61C arranged on the other axial side (downstream side) of the inner casing member 61A.

[0038] The inner casing member 61A has a longitudinal direction along the axial direction of the power generation turbine 11, and is disposed between the first stage rotor blades 23B and the second stage rotor blades 24B in the axial direction of the power generation turbine 11. A space 610 is formed inside the inner casing member 61A, and houses the shaft portion 111 and a generator 8 (in the illustrated example, a generator rotor 81 and a generator stator 82) described below.

[0039] The one-side cover member 61B is arranged on one side of the inner casing member 61A so as to cover one end of the shaft portion 111, including the one-side protrusion 114A and the one-side nut 115A screwed thereto, on one axial side of the first stage rotor blade 23B.

[0040] The other side cover member 61C is positioned on the other side of the inner casing member 61A so as to cover the other side end of the shaft portion 111, including the other side protrusion 114B and the other side nut 115B screwed thereto, on the other axial side of the second stage rotor blade 24B.

[0041] The generator 8 is configured to include a generator rotor 81 including permanent magnets formed on the outer circumferential surface of the rotor shaft 16 , and a generator stator 82 supported on the inner circumferential surface 611 of the inner casing 61 .

[0042] The generator rotor 81 is integrally formed on the outer circumferential surface of the rotor shaft 16, and the two have an integral structure. However, the generator rotor 81 and the rotor shaft 16 may be formed separately, and the generator rotor 81 may be supported on the outer circumferential surface of the rotor shaft. The generator stator 82 is supported on the inner circumferential surface 611 of the inner casing member 61A, and is disposed radially outward of the generator rotor 81. The generator rotor 81 and the generator stator 82 are disposed on the other side of a one-side radial bearing 103A (described later) and on the one side of a other-side radial bearing 103B in the axial direction of the rotor shaft 16. That is, the generator rotor 81 and the generator stator 82 are located between the one-side radial bearing 103A and the other-side radial bearing 103B in the axial direction of the rotor shaft 16.

[0043] The first stage rotor blades 23B are provided on one side of the rotor shaft 16 relative to the generator rotor 81. In addition, the first stage stator vanes 23A are supported by an inner circumferential surface 621 of the outer casing 62 or an outer circumferential surface 612 of the inner casing 61 on one side of the rotor shaft 16 relative to the first stage rotor blades 23B.

[0044] The first stage rotor blades 23B are attached to the outer peripheral surface of the one-side disk portion 113A described above with a gap therebetween in the circumferential direction. The first stage stator vanes 23A are supported by the inner peripheral surface 621 of the outer casing 62 and are provided on the inner peripheral surface 621 with a gap therebetween in the circumferential direction. In another embodiment, the first stage stator vanes 23A may be supported by the outer peripheral surface 612 (the outer peripheral surface 612B of the one-side cover member 61B) of the inner casing 61 and provided on the outer peripheral surface 612 (the outer peripheral surface 612B) with a gap therebetween in the circumferential direction, or may be supported by both the inner peripheral surface 621 of the outer casing 62 and the outer peripheral surface 612 of the inner casing 61 (the outer peripheral surface 612B of the one-side cover member 61B).

[0045] The second stage stator vane 24A is supported by an inner circumferential surface 621 of the outer casing 62 or an outer circumferential surface 612 of the inner casing 61 on the other side of the rotor shaft 16 relative to the generator rotor 81. In addition, the second stage rotor blade 24B is provided on the other side of the rotor shaft 16 relative to the second stage stator vane 24A.

[0046] The second stage rotor blades 24B are attached to the outer peripheral surface of the above-mentioned other-side disk portion 113B with a gap therebetween in the circumferential direction. The second stage stator vanes 24A are supported by the inner peripheral surface 621 of the outer casing 62 and are provided on the inner peripheral surface 621 with a gap therebetween in the circumferential direction. In another embodiment, the second stage stator vanes 24A may be supported by the outer peripheral surface 612 (the outer peripheral surface 612A of the inner casing member 61A) of the inner casing 61 and provided on the outer peripheral surface 612 (the outer peripheral surface 612A) with a gap therebetween in the circumferential direction, or may be supported by both the inner peripheral surface 621 of the outer casing 62 and the outer peripheral surface 612 of the inner casing 61 (the outer peripheral surface 612A of the inner casing member 61A).

[0047] The working fluid flow path 63 is defined between the outer peripheral surface 612 of the inner casing 61 and the inner peripheral surface 621 of the outer casing 62, and is configured to extend along the axial direction of the rotor shaft 16 from upstream of the first stage stator vane 23A to downstream of the second stage rotor blade 24B.

[0048] The working fluid flow passage 63 has a longitudinal direction along the axial direction of the power generation turbine 11 and has an annular cross section surrounding the periphery of the inner casing member 61A. The working fluid flow passage 63 is configured to guide the working fluid from one side to the other side between the outer casing 62 and the inner casing 61.

[0049] A one-side introduction passage 64A is formed on one side of the working fluid flow passage 63 for introducing the working fluid from one side along the axial direction into the working fluid flow passage 63. The one-side introduction passage 64A is defined by an inner surface 630A of an inlet casing 65A connected to one side of the outer casing 62, on one axial side of the one-side cover member 61B.

[0050] A second-side discharge passage 64B is formed on the other side of the working fluid flow passage 63 for discharging the working fluid in the axial direction from the working fluid flow passage 63 to the other side. The second-side discharge passage 64B is defined by an inner surface 630B of an outlet casing 65B connected to the other side of the outer casing 62, on the other axial side of the other-side cover member 61C.

[0051] The working fluid introduced from the one-side introduction passage 64A into the working fluid passage 63 passes through the first-stage stator vane 23A, and then acts on the first-stage rotor blade 23B to impart a rotational force to the shaft portion 111, thereby driving the first-stage axial turbine 23. The working fluid that has passed through the first-stage rotor blade 23B exchanges heat with heat generated in the generator 8 (generator rotor 81, generator stator 82) housed in the space 610 formed inside the inner casing member 61A while flowing through the working fluid passage 63. In other words, the working fluid flowing through the working fluid passage 63 absorbs the heat generated in the generator 8. As a result, the generator 8 is cooled, and the working fluid flowing through the working fluid passage 63 is heated.

[0052] The heated working fluid passes through the second-stage stator vanes 24A, and then acts on the second-stage rotor blades 24B to impart a rotational force to the shaft portion 111, thereby driving the second-stage axial turbine 24. In other words, the working fluid heated by heat exchange with the generator 8 in the working fluid passage 63 flows into the second-stage axial turbine 24, and this heated working fluid drives the second-stage axial turbine 24. The working fluid that has flowed through the second-stage axial turbine 24 is discharged from the working fluid passage 63 to the other-side discharge passage 64B, and flows out to the outside of the power-generating turbine 11.

[0053] The power generation turbine 11 configured as above has a structure in which the first stage axial turbine 23 consisting of the first stage rotor blades 23B and the first stage stator vanes 23A is provided on one side of the generator rotor 81, and the second stage axial turbine 24 consisting of the second stage rotor blades 24B and the second stage stator vanes 24A is provided on the other side. In other words, axial turbines are provided on both ends of the generator rotor 81. An axial turbine does not require a large scroll (casing) as in a radial turbine, making it possible to miniaturize the entire power generation turbine.

[0054] The working fluid flows through a working fluid flow path 63 defined between an outer peripheral surface 612 of the inner casing 61 and an inner peripheral surface 621 of the outer casing 62, in the order of the first stage rotor blades 23B, the first stage stator vanes 23A, the second stage rotor blades 24B, and the second stage stator vanes 24A. In other words, the working fluid that has passed through the first stage axial turbine 23 absorbs heat of the generator 8 generated in the generator rotor 81 and the generator stator 82 while flowing through the working fluid flow path 63, and then flows into the second stage axial turbine 24. With this configuration, the generator 8 can be cooled using the working fluid, making it unnecessary or possible to reduce the size of additional cooling mechanisms such as equipment required for cooling or cooling channels, thereby preventing the device from becoming larger.

[0055] The working fluid recovers the exhaust heat from the generator 8, thereby increasing the temperature of the working fluid at the inlet of the second-stage axial turbine 24, thereby improving the efficiency of the second-stage axial turbine 24. In other words, it is possible to achieve both cooling of the generator 8 and exhaust heat recovery.

[0056] Since axial flow turbines are provided on both ends of the rotor shaft 16, the weight is well balanced and no counterweight is required.

[0057] A space 610 formed inside the inner casing member 61A accommodates a first radial bearing 103A and an second radial bearing 103B which rotatably support the shaft portion 111. The first radial bearing 103A is disposed on one side of the generator rotor 81, and the second radial bearing 103B is disposed on the other side of the generator rotor 81. The one-side radial bearing 103A and the other-side radial bearing 103B are disposed so as to contact, at their respective inner peripheries, the outer periphery of the bearing 103A with the outer periphery of the shaft portion 111 of the rotor shaft 16 and rotatably support the shaft portion 111. The one-side radial bearing 103A and the other-side radial bearing 103B are also supported, at their respective outer peripheries, by the inner periphery 611 of the inner casing member 61A. In the following description, a device including the one-side radial bearing 103A and the other-side radial bearing 103B may be simply referred to as radial bearing device 103.

[0058] A space 610 formed inside the inner casing member 61A accommodates a thrust collar 101, a one-side thrust bearing 102A arranged facing the thrust collar 101 on one axial side of the thrust collar 101, and an other-side thrust bearing 102B arranged facing the thrust collar 101 on the other axial side of the thrust collar 101. In the following description, a device including the one-side thrust bearing 102A and the other-side thrust bearing 102B may be simply referred to as thrust bearing device 102.

[0059] The one-side radial bearing 103A, the other-side radial bearing 103B, the one-side thrust bearing 102A, and the other-side thrust bearing 102B may be configured by magnetic bearings.

[0060] With magnetic bearings, there is no need to use lubricating oil, and there is no need to create a device for supplying lubricating oil, so the size of the device can be suppressed. In addition, since no lubricating oil is used, it is possible to prevent oil (lubricating oil) from mixing with the working fluid.

[0061] The thrust collar 101 and the thrust bearing device 102 are disposed on the other side of the one-side radial bearing 103A and on one side of the generator rotor 81. That is, the generator rotor 81 and the generator stator 82 are disposed along the axial direction of the rotor shaft 16 between the thrust bearing device 102 and the other-side radial bearing 103B.

[0062] The blade height of the first stage stator vanes 23A is smaller than that of the second stage stator vanes 24A, and the blade height of the first stage rotor blades 23B is smaller than that of the second stage rotor blades 24B. Therefore, an inner circumferential surface 621 of an outer casing 62 accommodating the first stage axial turbine 23 and the second stage axial turbine 24 is formed so as to make the working fluid flow passage 63 wider in the radial direction at the position where the second stage axial turbine 24 is disposed than at the position where the first stage axial turbine 23 is disposed.

[0063] The above-mentioned power generation turbine 11 further includes a one-side seal portion 26A that seals between the rotor shaft 16 and the inner casing 61 on the other side (downstream side) of the first stage rotor blades 23B and on one side (upstream side) of the generator rotor 81.

[0064] The one-side seal portion 26A seals a gap between an inner circumferential surface 611 of the inner casing member 61A and an outer circumferential surface of the shaft portion 111 of the rotor shaft 16 in a space 610 formed inside the inner casing member 61A. The one-side seal portion 26A is disposed on one side of the one-side radial bearing 103A in the axial direction of the power generation turbine 11.

[0065] A ball bearing 27A is disposed between one side seal portion 26A and one side radial bearing 103A. Similarly, a ball bearing 27B is disposed between the other side seal portion 26B and the other side radial bearing 103B. When the power generation turbine 11 stops or trips due to a problem, these ball bearings 27A and 27B support the rotor shaft 16, thereby preventing contact between the radial bearing 103, which is a magnetic bearing, and the rotor shaft 16.

[0066] The one-side seal portion 26A may include a mechanical seal, or may include a labyrinth seal provided by machining the shaft portion 111 or the inner casing member 61A to have projections and recesses.

[0067] According to such a configuration, leakage of the working fluid that has passed through the first-stage rotor blades 23B into the inner casing 61 can be suppressed, and therefore a reduction in the working fluid flowing through the working fluid passage 63 can be suppressed compared to when the seal member 26 is not provided. As a result, compared to when the seal member is not provided, more of the generator heat generated in the generator rotor 81 and the generator stator 82 can be recovered, and the inlet temperature of the second-stage axial turbine 24 can be increased, and the efficiency of the second-stage axial turbine 24 can be improved.

[0068] In addition, since the working fluid leaking into the inner casing 61 between the high pressure region on the first stage axial turbine 23 side and the low pressure region on the second stage axial turbine 24 side can be sealed, the pressure inside the inner casing 61 can be kept low compared to a case where no seal member is provided. This makes it possible to reduce the thrust force acting on the rotor shaft 16 and the windage loss (loss) occurring inside the inner casing 61.

[0069] The power generation turbine 11 described above further includes an other-side seal portion 26B that seals between the rotor shaft 16 and the inner casing 61 on one side of the second stage rotor blades 24B and on the other side of the generator rotor 81. The other-side seal portion 26B seals a gap between an inner circumferential surface 611 of the inner casing member 61A and an outer circumferential surface of the shaft portion 111 of the rotor shaft 16 in a space 610 formed inside the inner casing member 61A. The other-side seal portion 26B is disposed on the other side of the other-side radial bearing 103B in the axial direction of the power generation turbine 11.

[0070] The one-side seal portion 26A may include a mechanical seal, or may include a labyrinth seal provided by machining the shaft portion 111 or the inner casing member 61A to have projections and recesses.

[0071] According to such a configuration, it is possible to reduce the amount of working fluid that has flowed from the working fluid flow path 63 into the inner casing 61 (inner casing member 61A) flowing out from between the second stage stator vanes 24A and the second stage rotor blades 24B into the working fluid flow path 63, and to suppress the generation of vortex flows in the working fluid passing through the second stage axial turbine 24. This makes it possible to improve the performance of the second stage axial turbine 24.

[0072] As shown in FIGS. 2 and 3, the power generation turbine 11 further includes a bypass line 40 that communicates between the inside of the inner casing 61 and a position in the working fluid flow passage 63 downstream of the second stage rotor blades 24B.

[0073] At one end of the bypass line 40, on one side of the second stage rotor blade 24B in the axial direction of the rotor shaft 16, an inlet side opening 40A is formed so as to open into a space 610 formed inside the inner casing member 61A.

[0074] The bypass line 40 passes through the axially extending portion 61A1 on the bottom side of the inner casing member 61A, below the vertical direction of the power generation turbine 11. The inlet side opening 40A is located below the bottom surface of the shaft portion 111 and near the inner surface of the axially extending portion 61A1. The axially extending portion 61A1 is a side portion that extends along the axial direction of the inner casing member 61A and is provided so that the distance from the axis CA is constant in the radial direction, and is a bottom side surface on the vertically lower side where the working fluid that has leaked into the inside of the inner casing 61 is likely to accumulate. By providing the inlet side opening 40A near the axially extending portion 61A1, it is possible to make it easier for the working fluid to flow into the inlet side opening 40A.

[0075] An inlet side opening 40A at the end of the bypass line 40 is connected to a radially extending introduction portion 40B of the bypass line 40, and the working fluid that has leaked into the inside of the inner casing member 61A passes through the inlet side opening 40A and flows through the radially extending introduction portion 40B of the bypass line 40. The radially extending introduction portion 40B is provided so as to penetrate the inner casing member 61A, the working fluid flow path 63, and the outer casing 62 along the radial direction, and extend to the outside of the outer casing 62.

[0076] The radially extending introduction portion 40B is connected to the axially extending portion 40C, and the working fluid that flows through the radially extending introduction portion 40B flows into the axially extending portion 40C. The axially extending portion 40C is provided outside the outer casing 62 along the axial direction of the rotor shaft 16.

[0077] The axially extending portion 40C is connected to the radially extending discharge portion 40D, and the working fluid that has flowed through the axially extending portion 40C flows into the radially extending discharge portion 40D. The radially extending discharge portion 40D is provided to penetrate the outer casing 62 and the working fluid flow path 63 along the radial direction. In addition, an outlet side opening 40E is formed at the other end of the bypass line 40 on the other side of the second stage rotor blade 24B in the axial direction of the rotor shaft 16 so as to open into the working fluid flow path 63. The radially extending discharge portion 40D is connected to the outlet side opening 40E, and the working fluid that has flowed through the radially extending discharge portion 40D is discharged to the outside of the bypass line 40 from the outlet side opening 40E.

[0078] According to this configuration, the working fluid flowing inside the inner casing 61 can be made to flow to the other side (downstream side) of the second stage rotor blade 24B in the working fluid flow path 63, thereby preventing the working fluid from accumulating inside the inner casing 61.

[0079] In addition, it is possible to reduce the amount of the working fluid flowing inside the inner casing 61 flowing out from between the second stage stator vanes 24A and the second stage rotor blades 24B into the working fluid flow passage 63, thereby suppressing the generation of vortex flows in the working fluid passing through the second stage axial turbine 24. This makes it possible to improve the performance of the second stage axial turbine 24.

[0080] The power generation turbine 11 is provided with both the other-side seal portion 26B and the bypass line 40. In the power generation turbine 11 provided with the other-side seal portion 26B and not the bypass line 40, the working fluid that has flowed into the space 610 inside the inner casing 61 can be reduced from flowing out from between the second-stage stator vane 24A and the second-stage rotor blade 24B into the working fluid flow passage 63. However, since the other-side seal portion 26B is provided, there is no discharge destination for the working fluid that has leaked into the inner casing member 61A, and the working fluid continues to accumulate inside the inner casing member 61A. However, by providing the other-side seal portion 26B and the bypass line 40, the working fluid that has leaked into the inner casing member 61A can be discharged to the outside of the inner casing member 61A, so that the accumulation of the working fluid inside the inner casing member 61A can be suppressed.

[0081] The power generation turbine 11 further includes at least one support 30 extending in the working fluid flow path 63 along the radial direction of the rotor shaft 16. One end of the support 30 is connected to an inner circumferential surface 621 of the outer casing 62, and the other end is connected to an outer circumferential surface 612 of the inner casing 61. The inner casing 61 is supported by the outer casing 62 by the support 30 described above. In the illustrated embodiment, the inner casing member 61A of the inner casing 61 is supported by the support 30.

[0082] The support part 30 is provided in the working fluid flow path 63 and is connected to the outer peripheral surface 612 of the inner casing 61 (the outer peripheral surface 612A of the inner casing member 61A), thereby also functioning as a cooling fin to promote cooling of the generator 8.

[0083] It is sufficient that at least one support portion 30 is arranged along the axial direction of the power generation turbine 11, and that at least one support portion 30 is also arranged in the circumferential direction of the outer circumferential surface 612 of the inner casing 61. In the embodiment shown in Fig. 3, eight support portions 30 are arranged at equal intervals in the circumferential direction.

[0084] The upstream end of the support portion 30 is located on one side (upstream side) of the generator stator 82 in the axial direction of the rotor shaft 16. Moreover, the downstream end of the support portion 30 is located on the other side (downstream side) of the generator stator 82 in the axial direction of the rotor shaft 16. With this configuration, the generator stator 82 can be effectively cooled by the support portion 30.

[0085] A portion of the bypass line 40 is formed inside the support part 30. In the illustrated embodiment, a through-hole 40B1 that penetrates the support part 30 along the radial direction is formed inside the support part 30. A portion of the bypass line 40 is composed of this through-hole 40B1. Also, a portion of the bypass line 40 may be composed of a pipe inserted into this through-hole 40B1.

[0086] According to this configuration, the bypass line 40 is provided inside the support part 30 that supports the inner casing 61. Therefore, compared to a case in which the bypass line 40 is not provided inside the support part 30 but is provided so as to extend inside the working fluid flow path 63 outside the support part 30, it is possible to suppress the occurrence of new flow path loss.

[0087] <Operation of cold ORC power generation device 1> Next, the operation of the cold ORC power generation device 1 having the above configuration will be described.

[0088] Vaporized propane guided from the exhaust side of the power generation turbine 11 passes through a circulation path 13 and is guided to a condenser 3. In the condenser 3, the vaporized propane is condensed and liquefied by the cold heat of the LNG. The propane liquefied in the condenser 3 is guided to a drain tank 19 and temporarily stored there.

[0089] The liquefied propane stored in the drain tank 19 is sucked out of the drain tank 19 by the operation of the circulation pump 5, and is guided to the outlet valve 7 via the circulation pump 5. At the outlet valve 7, the opening degree is controlled by the control unit so that a predetermined degree of superheat is maintained by the superheat sensor 29.

[0090] The liquefied propane that leaves the outlet valve 7 is guided to the evaporator 9, where it is evaporated by seawater SW and becomes vaporized propane. The vaporized propane that leaves the evaporator 9 has its flow rate adjusted by the turbine flow control valve 31, and is then guided to the power generation turbine 11 via the turbine inlet valve 33. Meanwhile, a portion of the vaporized propane bypasses the power generation turbine 11 by the bypass flow control valve 37 and is guided to the condenser 3.

[0091] The opening degree of the turbine flow rate control valve 31 and the bypass flow rate control valve 37 is controlled by the control unit based on the output of the pressure sensor 21 provided in the drain tank 19. Specifically, when the flow rate of LNG passing through the condenser 3 changes, the amount of heat exchanged in the condenser 3 changes, and so the amount of condensation of propane changes. This change is more noticeable because a plate type heat exchanger is used as the condenser 3, as compared to a shell-and-tube type heat exchanger. Fluctuations in the amount of condensation of propane appear as pressure fluctuations in the drain tank 19. The control unit controls the opening degree of the turbine flow rate control valve 31 so as to suppress these pressure fluctuations. After controlling the turbine flow rate control valve 31 to be fully open, the bypass flow rate control valve 37, which was fully closed, is opened and controlled.

[0092] For example, when the flow rate of LNG increases, the amount of condensation in the condenser 3 increases, the liquid level in the drain tank rises, and the pressure detected by the pressure sensor 21 decreases. In this case, the opening degree of the turbine flow control valve 31 is increased so as to increase the flow rate of propane flowing from the power generation turbine 11 to the condenser 3. Then, after the turbine flow control valve 31 is fully opened, the bypass flow control valve 37 is changed from fully closed to open, and the opening degree is adjusted by the control unit.

[0093] When the vaporized propane flows into the power generating turbine 11 through the turbine inlet valve 33, the vaporized propane rotates the turbine, driving a generator to generate electricity. The vaporized propane that has passed through the power generation turbine 11 is directed to the condenser 3 .

[0094] <Number control> Next, the control of the number of the two power generation turbines 11A, 11B will be described. The number of power generation turbines 11 is controlled by the control unit, and is determined by the flow rate of vaporized propane supplied from the turbine flow rate control valve 31. For example, the number is controlled based on the opening degree of the turbine flow rate control valve 31, and when the opening degree of the turbine flow rate control valve 31 is small, only the first power generation turbine 11A is operated (single operation), and when the opening degree of the turbine flow rate control valve 31 is large, both the first power generation turbine 11A and the second power generation turbine 11B are operated (two operation).

[0095] Specifically, as the opening degree of the turbine flow control valve 31 increases from zero, the opening degree of the first turbine inlet valve 33A is increased. This starts the first power generating turbine 11A and gradually increases the rotation speed and power generation amount. At this time, the second turbine inlet valve 33B is fully closed and the second power generating turbine 11B is not started (single operation).

[0096] Then, when the opening degree of the first turbine inlet valve 33A exceeds a predetermined value, the opening degree of the second turbine inlet valve 33B is gradually increased from fully closed to start the second power generation turbine 11B. When both power generation turbines 11A, 11B are in operation (two-unit operation), the opening degree of each turbine inlet valve 33A, 33B is controlled by a command from the control unit so that they operate at an operating point with high power generation efficiency.

[0097] When the opening of the turbine flow control valve 31 decreases and the flow rate of vaporized propane supplied to the power generation turbine 11 falls below a predetermined value, the control unit commands the second turbine inlet valve 33B to be closed, and the system transitions to single operation of only the first power generation turbine 11A.

[0098] The opening degree of the turbine inlet valve 33 may be controlled in response to the internal pressure of the drain tank 19, as shown in FIG.

[0099] The effects of the present embodiment described above are as follows. When the flow rate of LNG flowing through the LNG vaporization passage 12 changes, the amount of heat exchange in the condenser 3 changes. Therefore, two power generation turbines 11 are provided in parallel, and the number of power generation turbines 11 in operation is controlled according to the amount of heat exchange in the condenser 3. In this way, by operating each power generation turbine 11 at an operating point with good power generation efficiency according to the flow rate of LNG, power generation can be performed efficiently even when the flow rate of LNG fluctuates.

[0100] The amount of heat exchange in the condenser 3 changes according to the flow rate of LNG flowing through the LNG vaporization passage 12. Furthermore, the internal pressure of the drain tank 19, which temporarily stores the working fluid condensed in the condenser 3, changes according to the change in the amount of heat exchange in the condenser 3. Therefore, the amount of heat exchange in the condenser 3 may be obtained based on the flow rate of LNG flowing through the LNG vaporization passage 12 and / or the internal pressure of the drain tank 19. In this way, by controlling the opening degree of the turbine inlet valve 33 based on the flow rate of LNG and the internal pressure of the drain tank 19, each power generation turbine 11 can be operated in a region with good efficiency.

[0101] When the opening degree of the turbine inlet valve 33 of an operating power generation turbine 11 exceeds a predetermined value, the number of operating power generation turbines 11 can be easily controlled.

[0102] The power generation turbine 11 is configured as an integrated unit, and includes a rotor shaft 16, rotor blades 23B, 24B attached to the rotor shaft 16, a generator rotor 81 that rotates together with the rotor shaft 16, and a generator stator 82 disposed opposite the generator rotor 81. This allows the power generation turbine 11 to be started and stopped in a short time, and the number of units can be controlled in response to fluctuations in the LNG flow rate.

[0103] The cold ORC power generation apparatus and the operating method thereof described in each of the above-described embodiments can be understood, for example, as follows.

[0104] The cold-energy ORC power generation apparatus (1) according to the first aspect of the present disclosure includes a refrigerant vaporization flow path (12) through which a liquefied refrigerant (LNG) flows and vaporizes it, a condenser (3) that exchanges heat between the liquefied refrigerant (LNG) flowing through the refrigerant vaporization flow path and a working fluid that has been converted into an organic fluid (propane) to heat the liquefied refrigerant and condense the working fluid (propane), a liquid pump (5) that transports the working fluid (propane) condensed in the condenser, an evaporator (9) that evaporates the working fluid (propane) guided from the liquid pump by heat exchange with a heat source (SW), a plurality of power generation turbines (11) that are driven by the working fluid (propane) guided from the evaporator to generate power and are arranged in parallel with each other, and a control unit that controls the number of power generation turbines (11) in operation depending on the amount of heat exchange in the condenser (3).

[0105] When the flow rate of the liquefied refrigerant flowing through the refrigerant vaporization passage changes, the amount of heat exchange in the condenser changes. Therefore, multiple power generation turbines are provided in parallel, and the number of power generation turbines in operation is controlled according to the amount of heat exchange in the condenser. This allows each power generation turbine to operate at an operating point with good power generation efficiency according to the flow rate of the liquefied refrigerant, making it possible to generate power efficiently even when the flow rate of the liquefied refrigerant fluctuates.

[0106] In the cold-energy ORC power generation device (1) according to the second aspect of the present disclosure, in the above-mentioned first aspect, the control unit obtains the heat exchange amount of the condenser (3) based on the flow rate of the liquefied refrigerant flowing through the refrigerant vaporization passage and / or the internal pressure of a drain tank (19) that temporarily stores the working fluid condensed in the condenser (3).

[0107] The amount of heat exchange in the condenser changes depending on the flow rate of the liquefied refrigerant flowing through the refrigerant vaporization passage. Also, the internal pressure of the drain tank (19), which temporarily stores the working fluid condensed in the condenser (3), changes depending on the change in the amount of heat exchange in the condenser. Therefore, the amount of heat exchange in the condenser is obtained based on the flow rate of the liquefied refrigerant flowing through the refrigerant vaporization passage and / or the internal pressure of the drain tank.

[0108] The cold ORC power generation apparatus (1) according to the third aspect of the present disclosure, in the first or second aspect described above, includes a turbine inlet valve (33) provided on the inlet side of each of the power generation turbines (11) for adjusting the flow rate of the inflowing working fluid, and the control unit starts the second power generation turbine (11B) that is stopped when the opening degree of the first turbine inlet valve (33A) of the first power generation turbine (11A) in operation exceeds a predetermined value.

[0109] When the opening degree of the turbine inlet valve of an operating power generation turbine exceeds a predetermined value, the number of operating power generation turbines is increased, thereby making it possible to easily control the number of turbines.

[0110] A cold-energy ORC power generation apparatus (1) according to a fourth aspect of the present disclosure is any one of the first to third aspects, in which the power generation turbine (11) includes a rotor shaft (16), rotor blades (23B, 24B) attached to the rotor shaft (16), a generator rotor (81) rotating together with the rotor shaft (16), and a generator stator (82) arranged opposite the generator rotor (81).

[0111] The power generating turbine is configured as an integrated unit that includes a rotor shaft, rotor blades attached to the rotor shaft, a generator rotor that rotates together with the rotor shaft, and a generator stator disposed opposite the generator rotor. This allows the power generating turbine to be started and stopped in a short time, and the number of turbines can be controlled in response to fluctuations in the refrigerant flow rate.

[0112] A method for operating a cold-energy ORC power generation system (1) according to a first aspect of the present disclosure is a method for operating a cold-energy ORC power generation system (1) including a refrigerant vaporization flow path (12) through which a liquefied refrigerant (LNG) flows and vaporizes it, a condenser (3) that exchanges heat between the liquefied refrigerant (LNG) flowing through the refrigerant vaporization flow path and a working fluid that has been converted into an organic fluid (propane) to heat the liquefied refrigerant and condense the working fluid (propane), a liquid pump (5) that transports the working fluid (propane) condensed in the condenser, an evaporator (9) that exchanges heat with a heat source (SW) to evaporate the working fluid (propane) guided from the liquid pump, and a plurality of power generation turbines (11) that are driven by the working fluid (propane) guided from the evaporator to generate power and are arranged in parallel with each other, and the number of power generation turbines (11) in operation is controlled according to the amount of heat exchange in the condenser (3). [Explanation of symbols]

[0113] 1 Cold ORC power generator 3. Condenser 5 Circulation pump (liquid pump) 6 Casing 7 Outlet valve (liquid pump outlet valve) 8. Generator 9. Evaporator 11 Power generating turbines 11A First generating turbine 11B No. 2 power generating turbine 11C 3rd power generating turbine 12 LNG vaporization path (refrigerant vaporization path) 13 Circulation route (organic fluid circulation system) 15 LNG supply valve 16 rotor shaft 17 Trim heater 19 Drain tank 21 Pressure Sensor 23 First stage axial flow turbine 23A 1st stage stator vane 23B 1st stage rotor blade 24 Second stage axial flow turbine 24A 2nd stage stator vane 24B 2nd stage rotor blade 25 Mini Flow Valve 26 Sealing material 26A One side seal 26B Other side seal part 27A Ball Bearing 27B Ball Bearing 28 Miniflow Circulation Channel 29 Superheat Sensor 30 Support part 31 Turbine flow control valve 33 Turbine inlet valve 33A First turbine inlet valve 33B No. 2 turbine inlet valve 33C 3rd turbine inlet valve 35 Bypass Route 37 Bypass flow control valve 40 Bypass Line 40A Inlet opening 40B Radial extension lead-in section 40B1 penetration part 40C Axial extension 40D radially extending discharge section 40E Exit side opening 61 Inner casing 61A Inner casing member 61A1 axial extension part 61B One side cover member 61C other side cover member 62 Outer casing 63 Working fluid flow path 64A One-side lead-in 64B Other side discharge path 65A Inlet Casing 65B Outlet casing 81 Generator rotor 82 Generator stator 101 Thrust collar 102 Thrust bearing device 102A One-sided thrust bearing 102B other side thrust bearing 103 Radial bearing 103A One-sided radial bearing 103B other side radial bearing 111 Shaft section 112A external surface 112B external surface 113A One side disk part 113B other side disk part 114A One side protrusion 114B Other side protrusion 115A One-side nut 115B other side nut 610 Space 611 Inner surface 612 Outer surface 612A outer surface 612B outer surface 621 Inner surface 630A inner surface 630B inner surface CA axis

Claims

1. a refrigerant vaporization flow path through which a liquefied refrigerant flows and vaporizes; a condenser that exchanges heat between the liquefied refrigerant flowing through the refrigerant vaporization flow path and the working fluid that has been converted into an organic fluid, thereby heating the liquefied refrigerant and condensing the working fluid; a liquid pump for transporting the working fluid condensed in the condenser; an evaporator that evaporates the working fluid guided from the liquid pump by heat exchange with a heat source; a plurality of power generating turbines arranged in parallel to each other, the power generating turbines being driven by the working fluid guided from the evaporator to generate power; a control unit that controls the number of the power generation turbines in operation in accordance with a heat exchange amount of the condenser; A cold ORC power generation device equipped with the above.

2. The cold-energy ORC power generation device of claim 1, wherein the control unit obtains the heat exchange amount of the condenser based on the flow rate of liquefied refrigerant flowing through the refrigerant vaporization passage and / or the internal pressure of a drain tank that temporarily stores the working fluid condensed in the condenser.

3. a turbine inlet valve provided on an inlet side of each of the power generation turbines to adjust a flow rate of the inflowing working fluid; The cold ORC power generation system according to claim 2 , wherein the control unit starts the second power generation turbine that is stopped when the opening degree of the first turbine inlet valve of the first power generation turbine that is in operation exceeds a predetermined value.

4. 2. The cold ORC power generation system according to claim 1, wherein the power generation turbine comprises a rotor shaft, rotor blades attached to the rotor shaft, a generator rotor rotating together with the rotor shaft, and a generator stator arranged opposite the generator rotor.

5. a refrigerant vaporization flow path through which a liquefied refrigerant flows and vaporizes; a condenser that exchanges heat between the liquefied refrigerant flowing through the refrigerant vaporization flow path and the working fluid that has been converted into an organic fluid, thereby heating the liquefied refrigerant and condensing the working fluid; a liquid pump for transporting the working fluid condensed in the condenser; an evaporator that evaporates the working fluid guided from the liquid pump by heat exchange with a heat source; a plurality of power generating turbines arranged in parallel to each other, the power generating turbines being driven by the working fluid guided from the evaporator to generate power; A method for operating a cold ORC power generation system comprising: A method for operating a cold ORC power generation system, comprising controlling the number of power generation turbines in operation according to the amount of heat exchanged in the condenser.

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