Organic rankine cycle power plant

Abstract

To provide an organic Rankine cycle power generation plant capable of suppressing deterioration of internal efficiency of a turbine even when the turbine is operated at a partial load.SOLUTION: An organic rankine cycle power generation plant includes a circulation line through which an organic medium circulates, an evaporator provided in the circulation line and configured to evaporate the organic medium by heat exchange with a heat medium, at least one turbine generator including a turbine driven by the organic medium evaporated by the evaporator and a generator connected to the turbine, a condenser configured to condense the organic medium discharged from the turbine by heat exchange with liquefied natural gas, a pressure ratio information acquisition unit configured to acquire pressure ratio information indicating a pressure ratio of the turbine, and a turbine control unit configured to control a rotational speed of the turbine on the basis of the pressure ratio information acquired by the pressure ratio information acquisition unit.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to organic Rankine cycle power plants. [Background technology]

[0002] Patent Document 1 discloses a Rankine cycle turbine plant equipped with a turbine with a variable nozzle. Patent Document 2 discloses a Rankine cycle device equipped with a pump, an evaporator, an expander, and a condenser provided on a working fluid circuit. In this Rankine cycle device, a generator is connected to the expander, and the generator output when the target pressure difference between the inlet pressure and outlet pressure of the expander is increased by a predetermined value and the generator output when the target pressure difference is decreased by a predetermined value are stored, and the target pressure difference is updated to the target pressure difference that maximizes the power generation output. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 60-013903 [Patent Document 2] Patent Publication No. 2021-095852 Summary of the Invention [Problem to be solved by the invention]

[0004] The turbine with a variable nozzle described in Patent Document 1 can suppress efficiency decline by using the variable nozzle, but in turbines without a variable nozzle, the internal efficiency of the turbine decreases with fluctuations in the turbine's pressure ratio. Also, when the expander in the configuration of Patent Document 2 is a turbine, the internal efficiency of the turbine decreases as the speed ratio U / C0, which is the ratio of the turbine blade peripheral speed U to the fluid velocity C0, deviates from the optimal speed ratio. Therefore, when the turbine is operating at partial load, even if the turbine rotation speed is changed in accordance with the pressure difference between the turbine's inlet pressure and outlet pressure, as in the method described in Patent Document 2, the effect of suppressing declines in the turbine's internal efficiency is limited.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide an organic Rankine cycle power plant configured to drive a turbine connected to a generator with an organic heat medium, which is capable of suppressing a decrease in the internal efficiency of the turbine even when the turbine is operated at a partial load. [Means for solving the problem]

[0006] In order to achieve the above object, an organic Rankine cycle power plant according to at least one embodiment of the present disclosure comprises: a circulation line through which the organic medium circulates; an evaporator provided in the circulation line for evaporating the organic medium by heat exchange with a heat medium; at least one turbine generator including a turbine driven by the organic medium evaporated in the evaporator and a generator connected to the turbine; a condenser for condensing the organic medium leaving the turbine by heat exchange with liquefied natural gas; a pressure ratio information acquisition unit configured to acquire pressure ratio information indicating a pressure ratio of the turbine; a turbine control unit configured to control a rotation speed of the turbine based on the pressure ratio information acquired by the pressure ratio information acquisition unit; Equipped with. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, there is provided an organic Rankine cycle power plant configured to drive a turbine connected to a generator using an organic heat medium, the organic Rankine cycle power plant being capable of suppressing a decrease in the internal efficiency of the turbine even when the turbine is operated at a partial load. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of an organic Rankine cycle power plant 2 according to an embodiment. [Figure 2] 2 is a diagram showing an example of a detailed configuration of a plurality of turbine generators 10 and their surroundings in the plant 2 shown in FIG. 1. FIG. [Figure 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control device 90. [Figure 4] FIG. 2 is a block diagram showing an example of the functional configuration of a control device 90. [Figure 5A] FIG. 10 is a diagram showing the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of the plant 2 is 100%. [Figure 5B] FIG. 10 is a diagram showing the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of the plant 2 is 75%. [Figure 5C] FIG. 10 is a diagram showing the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of the plant 2 is 60%. [Figure 5D] FIG. 10 is a diagram showing the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of the plant 2 is 50%. [Figure 5E] FIG. 10 is a diagram showing the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of the plant 2 is 30%. [Figure 6] 10 is a diagram showing an example of correlation information T indicating the correlation between the operating load of the plant 2, the pressure ratio of the turbine 30, and the rotation speed of the turbine 30 for each of a plurality of turbine generators 10A, 10B, and 10C. [Figure 7] FIG. 2 is a diagram showing the relationship between the load of a turbine generator and the internal efficiency of the turbine. [Figure 8] FIG. 10 is a diagram showing the relationship between the operating load of the plant 2 and the internal efficiency of the turbine during operation. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0010] FIG. 1 is a diagram showing a schematic configuration of an organic Rankine cycle power plant 2 (hereinafter simply referred to as "plant 2") according to one embodiment. As shown in FIG. 1 , the plant 2 includes a circulation line 4, a pump 6, an organic medium evaporator 8, a plurality of turbine generators 10, an organic medium condenser 12, a seawater line 14, an LNG tank 16, an LNG line 18, and a trim heater 20.

[0011] The circulation line 4 is composed of piping, and an organic medium as a working fluid circulates through the circulation line 4. As the organic medium, a low-boiling-point medium having a boiling point lower than that of water is used. The type of organic medium is not particularly limited, but may be, for example, the following substances. Alkanes such as butane, propane, pentane, hexane, heptane, octane, and decane Cyclic alkanes such as cyclopentane and cyclohexane Refrigerants such as R1234zee, R1234yf, R134a, and R245fa A combination of the above

[0012] The pump 6 is provided between the organic medium condenser 12 and the organic medium evaporator 8 in the circulation line 4 , and is configured to pump the organic medium condensed in the organic medium condenser 12 to the organic medium evaporator 8 .

[0013] The organic medium evaporator 8 is provided downstream of the pump 6 in the circulation line 4. The organic medium evaporator 8 is a heat exchanger configured to heat and evaporate the organic medium flowing through the circulation line 4 by heat exchange between the organic medium flowing through the circulation line 4 and seawater as a heat medium flowing through the seawater line 14. The seawater flowing through the seawater line 14 is cooled by heat exchange with the organic medium in the organic medium evaporator 8 and is discharged from the organic medium evaporator 8 as wastewater.

[0014] The multiple turbine generators 10 are arranged in parallel on the circulation line 4. The circulation line 4 branches into multiple lines downstream of the organic medium evaporator 8, each passing through a multiple number of turbine generators 10, and then joins together upstream of the organic medium condenser 12.

[0015] In the illustrated example, the multiple turbine generators 10 are three turbine generators 10A, 10B, and 10C. The circulation line 4 branches into three branch lines 4a, 4a, and 4c downstream of the organic medium evaporator 8, with the turbine generator 10A provided in the branch line 4a, the turbine generator 10B provided in the branch line 4b, and the turbine generator 10B provided in the branch line 4c. The three branch lines 4a, 4b, and 4c join together upstream of the organic medium condenser 12.

[0016] In the illustrated example, the circulation line 4 is provided with a bypass line 5 that bypasses the three turbine generators 10, and the bypass line 5 is provided with a bypass valve 22.

[0017] The organic media that have exited the turbines (described later) in each of the plurality of turbine generators 10 A, 10 B, and 10 C join together upstream of the organic media condenser 12 and are supplied to the organic media condenser 12 .

[0018] The organic medium condenser 12 is provided in the circulation line 4 between the multiple turbine generators 10 and the pump 6. The organic medium condenser 12 is a heat exchanger configured to cool and condense the organic medium by heat exchange between the organic medium flowing through the circulation line 4 (the organic medium exiting the turbines described below in each of the multiple turbine generators 10A, 10B, and 10C) and LNG (liquefied natural gas) supplied from an LNG tank 16 as a cold heat source. The LNG flowing through the LNG line 18 is heated and evaporated by heat exchange with the organic medium in the organic medium condenser 12, becoming natural gas, which is supplied to the trim heater 20. The natural gas supplied to the trim heater 20 is further heated by heat exchange with seawater supplied from a branch line 15 branching off from the seawater line 14, and is used as fuel, etc.

[0019] 1 , a flow control valve 19 for adjusting the flow rate of LNG in the LNG line 18 is provided in the LNG line 18 at a position between the LNG tank 16 and the organic medium condenser 12. In addition, a flow meter 45 for measuring the flow rate of LNG in the LNG line 18 is provided in the LNG line 18 at a position between the LNG tank 16 and the organic medium condenser 12.

[0020] FIG. 2 is a diagram showing an example of a detailed configuration of the plurality of turbine generators 10 and their surroundings in the plant 2 shown in FIG. 2 , each of the plurality of turbine generators 10A, 10B, 10C includes a turbine 30 and a generator 32 connected to the turbine 30. An inverter device 34 is connected to the generator 32 of each of the turbine generators 10A, 10B, 10C. The inverter device 34 includes a converter 36 that converts the AC current output from the generator 32 into DC current, and an inverter 38 that converts the DC current output from the converter 36 into AC current, and converts the frequency of the output of the generator 32 and outputs it to the outside of the plant 2.

[0021] As shown in FIG. 2, the plant 2 includes a pressure gauge 40A that measures the inlet pressure of the turbine 30 of the turbine generator 10A, a pressure gauge 42A that measures the outlet pressure of the turbine 30 of the turbine generator 10A, a pressure gauge 40B that measures the inlet pressure of the turbine 30 of the turbine generator 10B, a pressure gauge 42B that measures the outlet pressure of the turbine 30 of the turbine generator 10B, a pressure gauge 40C that measures the inlet pressure of the turbine 30 of the turbine generator 10C, and a pressure gauge 42C that measures the outlet pressure of the turbine 30 of the turbine generator 10C.

[0022] 2, the plant 2 includes a control device 90 for controlling the rotation speed of the turbine 30 and the rotation speed of the generator 32 in each of the multiple turbine generators 10A, 10B, and 10C. The control device 90 controls the rotation speed of the turbine 30 and the generator 32 via the inverter device 34 for each of the multiple turbine generators 10A, 10B, and 10C.

[0023] Fig. 3 is a diagram showing an example of the hardware configuration of the control device 90. Fig. 4 is a block diagram showing an example of the functional configuration of the control device 90. 3, the control device 90 is configured using a computer including, for example, a processor 91, a RAM (Random Access Memory) 92, a ROM (Read Only Memory) 93, an HDD (Hard Disk Drive) 94, an input I / F 96, and an output I / F 98, all of which are connected to one another via a bus 95. The control device 90 is also configured by the computer executing a program that realizes each function of the control device 90. The functions of each part of the control device 90 described below are realized, for example, by loading a program stored in ROM 93 into RAM 92 and executing it with the processor 91, as well as by reading and writing data from and to the RAM 92 and ROM 93. The hardware that makes up the control device 90 may be concentrated in one location or may be distributed across multiple locations.

[0024] As shown in FIG. 4, the control device 90 includes an operating load information acquisition unit 50, a pressure ratio information acquisition unit 52, and a turbine control unit . The operating load information acquisition unit 50 acquires operating load information S L Here, the operating load information acquiring unit 50 acquires, for example, the ratio F1 / Fmax between the flow rate F1 of LNG measured by the flow meter 45 (see FIG. 1) and the maximum flow rate Fmax set in advance, as the operating load information S L Alternatively, the ratio F2 / Fmax of the control command value F2 of the LNG flow rate for the flow rate adjustment valve 19 (see FIG. 1) and the preset maximum flow rate Fmax may be acquired as the operating load information S L It may be obtained as.

[0025] The pressure ratio information acquisition unit 52 acquires pressure ratio information S indicating the pressure ratio of the turbine 30 for each of the turbine generators 10A, 10B, and 10C. PSpecifically, the pressure ratio information acquisition unit 52 acquires the inlet pressure PAi of the turbine 30 of the turbine generator 10A measured by the pressure gauge 40A and the outlet pressure PAo of the turbine 30 of the turbine generator 10A measured by the pressure gauge 42A, and calculates the ratio PAi / PAo of the inlet pressure PAi to the outlet pressure PAo as the pressure ratio of the turbine 30 of the turbine generator 10A, thereby obtaining pressure ratio information S P Furthermore, the pressure ratio information acquisition unit 52 acquires the inlet pressure PBi of the turbine 30 of the turbine generator 10B measured by the pressure gauge 40B and the outlet pressure PBo of the turbine 30 of the turbine generator 10B measured by the pressure gauge 42B, and calculates the ratio PBi / PBo of the inlet pressure PBi and the outlet pressure PBo as the pressure ratio of the turbine 30 of the turbine generator 10B, thereby obtaining pressure ratio information S of the turbine 30 of the turbine generator 10B. P Furthermore, the pressure ratio information acquisition unit 52 acquires the inlet pressure PCi of the turbine 30 of the turbine generator 10C measured by the pressure gauge 40C and the outlet pressure PCo of the turbine 30 of the turbine generator 10C measured by the pressure gauge 42C, and calculates the ratio PCi / PCo of the inlet pressure PCi and the outlet pressure PCo as the pressure ratio of the turbine 30 of the turbine generator 10C, thereby obtaining pressure ratio information S P Obtain the ratio PCi / PCo as:

[0026] The turbine control unit 54 includes an operating unit number determination unit 56, a correlation information reference unit 58, and a rotation speed determination unit 60. Hereinafter, a method for determining the number of operating turbine generators 10 by the operating unit number determination unit 56 will be described with reference to Figures 5A to 5E.

[0027] The operating vehicle number determination unit 56 determines the number of vehicles in operation based on the operating load information S L The number of operating turbine generators 10 is determined according to the operating load of the plant 2 indicated by the symbol . Here, the number of operating turbine generators 10 refers to the number of operating turbine generators 10 among the plurality of turbine generators 10A, 10B, and 10C.

[0028] The operating number determination unit 56 is configured to be able to execute a continuous operating number mode in which the number of operating turbine generators 10 is continuously changed according to the operating load of the plant 2, and a skip operating number mode in which the number of operating turbine generators 10 is discontinuously changed according to the operating load of the plant 2.

[0029] 5A to 5E, the load (%) of each of the multiple turbine generators 10A, 10B, and 10C in the continuous operating number mode is shown by a solid bar graph, and the load (%) of each of the multiple turbine generators 10A, 10B, and 10C in the skip operating number mode is shown by a dotted bar graph. Note that the open bars represent the case where variable speed control (described below) of the turbine 30 is performed, and the hatched bars represent the case where fixed speed control of the turbine 30 is performed (comparative form). That is, the open solid bar represents the case where continuous operating number mode and variable speed control of the turbine 30 are performed, the open dotted bar represents the case where skip operating number mode and variable speed control of the turbine 30 are performed, and the hatched solid bar represents the case where continuous operating number mode and fixed speed control of the turbine 30 are performed.

[0030] FIG. 5A shows the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of plant 2 is 100%. FIG. 5B shows the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of plant 2 is 75%. FIG. 5C shows the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of plant 2 is 60%. FIG. 5D shows the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of plant 2 is 50%. FIG. 5E shows the number of operating turbine generators 10 and the load (%) of each of the turbine generators 10A, 10B, and 10C when the operating load of plant 2 is 30%.

[0031] First, the continuous operating unit number mode will be described. 5A and 5B, in the continuous operating unit number mode, when the operating load of the plant 2 is between 100% (the maximum load of the plant 2) and a predetermined first predetermined load L1 (e.g., 70%), the operating unit number determination unit 56 determines the number of operating turbine generators 10 to be three (i.e., the total number of turbine generators 10 included in the plant 2), and uniformly reduces the loads of the multiple turbine generators 10A, 10B, and 10C as the operating load of the plant 2 decreases. For example, when the operating load of the plant 2 is 100% as shown in FIG. 5A, the load of each of the multiple turbine generators 10A, 10B, and 10C is 100%, whereas when the operating load of the plant 2 is 75% as shown in FIG. 5B, the load of each of the multiple turbine generators 10A, 10B, and 10C is 75%, and the loads of the multiple turbine generators 10A, 10B, and 10C are uniformly reduced by 25% from 100%.

[0032] 5C , in the continuous operating number mode, when the operating load of the plant 2 is between the first predetermined load L1 and a predetermined second predetermined load L2 (e.g., 30%), the operating number determination unit 56 determines the number of operating turbine generators 10 to be two (i.e., the total number of turbine generators 10 included in the plant 2 minus one). In the example shown in FIG. 5C , of the three turbine generators 10A, 10B, and 10C, two turbine generators (the turbine generators 10A and 10B in the example shown in FIG. 5C ) continue to operate, while the operation of one turbine generator 10C is suspended. Therefore, when the operating load of the plant 2 is 60%, the load on the turbine generators 10A and 10B is greater than when the operating load of the plant 2 is 75% (see FIG. 5B ).

[0033] 5C and 5D, in the continuous operating unit number mode, when the operating load of the plant 2 is between the first predetermined load L1 and the second predetermined load L2, the loads of the turbine generators 10A, 10B are uniformly reduced as the operating load of the plant 2 decreases. For example, when the operating load of the plant 2 is 60% as shown in Fig. 5C, the loads of each of the turbine generators 10A, 10B are 90%, whereas when the operating load of the plant 2 is 50% as shown in Fig. 5D, the loads of each of the turbine generators 10A, 10B are 75%, and the loads of the turbine generators 10A, 10B are uniformly reduced by 15% from 90%.

[0034] As shown in Fig. 5E, in the continuous operating number mode, when the operating load of the plant 2 becomes equal to or less than the second predetermined load L2, the operating number determination unit 56 determines the number of operating turbine generators 10 to be one. In the example shown in Fig. 5E, one of the three turbine generators 10A, 10B, and 10C (in the example shown in Fig. 5E, the turbine generator 10A) continues to operate, and the operation of the other two turbine generators 10B and 10C is suspended. Therefore, when the operating load of the plant 2 is 30%, the load on the turbine generator 10A is greater than when the operating load of the plant 2 is 50% (see Fig. 5D).

[0035] In this way, in a first case where the operating load of the plant 2 is a load between the maximum load and the first predetermined load L1, the turbine control unit 54 uniformly reduces the loads of the multiple turbine generators 10A, 10B, 10C as the operating load of the plant 2 decreases, and in a second case where the operating load of the plant 2 is equal to or less than the first predetermined load L1, the turbine control unit 54 reduces the number of operating turbine generators 10 less than in the first case. Furthermore, in the continuous operating number mode, when the operating load of the plant 2 is a load between the first predetermined load L1 and the second predetermined load L2, the turbine control unit 54 uniformly reduces the loads of the multiple turbine generators 10A, 10B as the operating load of the plant 2 decreases, and when the operating load of the plant 2 is equal to or less than the second predetermined load L2, the turbine control unit 54 reduces the number of operating turbine generators 10 less than in a case where the operating load of the plant 2 is a load between the first predetermined load L1 and the second predetermined load L2.

[0036] Next, the operating unit number skip mode will be described. 5A and 5B, in the operating-unit-number-skip mode, when the operating load of the plant 2 is between 100% (maximum load) and a predetermined third predetermined load L3 (e.g., 30%), the operating-unit-number determination unit 56 determines the number of operating turbine generators 10 to be three (i.e., the total number of turbine generators 10 included in the plant 2), and uniformly reduces the loads of the multiple turbine generators 10A, 10B, and 10C as the operating load of the plant 2 decreases. For example, when the operating load of the plant 2 is 100% as shown in FIG. 5A, the load of each of the multiple turbine generators 10A, 10B, and 10C is 100%, whereas when the operating load of the plant 2 is 75% as shown in FIG. 5B, the load of each of the multiple turbine generators 10A, 10B, and 10C is 75%, and the loads of the multiple turbine generators 10A, 10B, and 10C are uniformly reduced from 100% by 25%. 5C, when the operating load of the plant 2 is 60%, the load of each of the multiple turbine generators 10A, 10B, and 10C is 60%, and the loads of the multiple turbine generators 10A, 10B, and 10C are uniformly reduced by 40% from 100%. Also, as shown in FIG. 5D, when the operating load of the plant 2 is 50%, the load of each of the multiple turbine generators 10A, 10B, and 10C is 50%, and the loads of the multiple turbine generators 10A, 10B, and 10C are uniformly reduced by 50% from 100%.

[0037] As shown in Fig. 5E, in the operating-unit-number-skip mode, when the operating load of the plant 2 becomes equal to or less than the third predetermined load L3, the operating-unit-number determination unit 56 determines the number of operating turbine generators 10 to be one. In the example shown in Fig. 5E, one of the three turbine generators 10A, 10B, and 10C (in the example shown in Fig. 5E, the turbine generator 10A) continues to operate, and the operation of the other two turbine generators 10B and 10C is suspended. Therefore, when the operating load of the plant 2 is 30%, the load on the turbine generator 10A is greater than when the operating load of the plant 2 is 50% (see Fig. 5D).

[0038] In this way, in the first case where the operating load of the plant 2 is a load between the maximum load and the third predetermined load L3, the turbine control unit 54 uniformly reduces the loads of the multiple turbine generators 10A, 10B, 10C as the operating load of the plant 2 decreases, and in the second case where the operating load of the plant 2 is equal to or less than the third predetermined load L3, the turbine control unit 54 reduces the number of operating turbine generators 10 by two compared to the first case.

[0039] Furthermore, in order to suppress a decrease in the internal efficiency of the turbine 30 when each of the multiple turbine generators 10A, 10B, 10C is operating at partial load, the turbine control unit 54 performs variable speed control of the turbine 30 for each of the multiple turbine generators 10A, 10B, 10C as described below.

[0040] FIG. 6 shows an example of correlation information T indicating the correlation between the operating load of the plant 2, the pressure ratio of the turbine 30, and the rotation speed of the turbine 30 for each of the multiple turbine generators 10A, 10B, and 10C. Here, the correlation information R common to the three turbine generators 10A, 10B, and 10C will be described using an example in which the three turbine generators 10A, 10B, and 10C have the same configuration. That is, the correlation information T shown in FIG. 6 is used to determine the rotation speed of the turbine 30 for each of the multiple turbine generators 10A, 10B, and 10C. The correlation information T shown in FIG. 6 indicates the relationship between the range of the pressure ratio of the turbine 30 and the rotation speed of the turbine 30 for each operating load of the plant 2. The correlation information T indicates that the rotation speed of the turbine 30 decreases as the operating load of the plant 2 decreases, and indicates that the rotation speed of the turbine 30 decreases as the pressure ratio of the turbine 30 decreases for each operating load of the plant 2. In the illustrated example, the number of operating turbines 30 is shown together with the rotation speed of the turbine 30, but the number of operating turbines 30 is determined by the operating number determination unit 56 as described above.

[0041] The correlation information reference unit 58 shown in Fig. 4 references the correlation information T shown in Fig. 6. The rotation speed determination unit 60 shown in Fig. 4 uses the operating load information S acquired by the operating load information acquisition unit 50 for each of the plurality of turbine generators 10A, 10B, and 10C. L and the pressure ratio information S acquired by the pressure ratio information acquisition unit 52. P and correlation information T referenced by the correlation information reference unit 58. The turbine control unit 54 also controls the rotation speed of the turbine 30 of each of the plurality of turbine generators 10A, 10B, 10C to the rotation speed determined by the rotation speed determination unit 60. A specific example of a method for determining the rotation speed of the turbine 30 for each of the plurality of turbine generators 10A, 10B, 10C using the correlation information T shown in Fig. 6 will be described below.

[0042] For example, the driving load information S acquired by the driving load information acquisition unit 50 L The operating load of the plant 2 indicated by is 100%, and the pressure ratio information S of the turbine 30 of the turbine generator 10A acquired by the pressure ratio information acquisition unit 52 is P When the pressure ratio indicated by (i.e., the above-mentioned ratio PAi / PAo) is within the range of 4 to 5, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10A to be 10,000 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 100% and the pressure ratio of 4 to 5 in the correlation information T referenced by the correlation information reference unit 58. Also, when the operating load information S L The operating load of the plant 2 indicated by is 100%, and the pressure ratio information S of the turbine 30 of the turbine generator 10B acquired by the pressure ratio information acquisition unit 52 is P When the pressure ratio indicated by (i.e., the above-mentioned ratio PBi / PBo) is within the range of 4 to 5, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10B to be 10,000 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 100% and the pressure ratio of 4 to 5 in the correlation information T referenced by the correlation information reference unit 58. Also, when the operating load information S LThe operating load of the plant 2 indicated by is 100%, and the pressure ratio information S of the turbine 30 of the turbine generator 10C acquired by the pressure ratio information acquisition unit 52 is P If the pressure ratio indicated by (i.e., the above-mentioned ratio PCi / PCo) is a value within the range of 4 to 5, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10C to be 10,000 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 100% and the pressure ratio of 4 to 5 in the correlation information T referenced by the correlation information reference unit 58.

[0043] In addition, for example, in the operating vehicle number continuous mode described with reference to FIGS. 5A to 5E, the operating load information S L The operating load of the plant 2 indicated by is 60%, and the pressure ratio information S of the turbine 30 of the turbine generator 10A acquired by the pressure ratio information acquisition unit 52 is P When the pressure ratio indicated by (i.e., the above-mentioned ratio PAi / PAo) is a value within the range of 4 to 5, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10A to be 9700 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 60% and the pressure ratio of 4 to 5 in the correlation information T referenced by the correlation information reference unit 58. Also, in the continuous number of operating units mode described with reference to Figs. 5A to 5E, the operating load information S L The operating load of the plant 2 indicated by is 60%, and the pressure ratio information S of the turbine 30 of the turbine generator 10B acquired by the pressure ratio information acquisition unit 52 is P When the pressure ratio indicated by (i.e., the above-mentioned ratio PBi / PBo) is within the range of 4 to 5, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10B to be 9700 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 60% in the correlation information T referenced by the correlation information reference unit 58 and the pressure ratio of 4 to 5. Note that in the continuous operating unit number mode described with reference to FIGS. 5A to 5E, the operating load information S acquired by the operating load information acquisition unit 50 L When the operating load of the plant 2 indicated by is 60%, the operation of the turbine generator 10C is stopped.

[0044] In addition, for example, in the operating vehicle number skip mode described with reference to FIGS. 5A to 5E, the driving load information S L The operating load of the plant 2 indicated by is 60%, and the pressure ratio information S of the turbine 30 of the turbine generator 10A acquired by the pressure ratio information acquisition unit 52 is P When the pressure ratio indicated by (i.e., the above-mentioned ratio PAi / PAo) is a value within the range of 3 to 4, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10A to be 8500 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 60% and the pressure ratio of 3 to 4 in the correlation information T referenced by the correlation information reference unit 58. Also, in the operating unit number skip mode described with reference to Figs. 5A to 5E, L The operating load of the plant 2 indicated by is 60%, and the pressure ratio information S of the turbine 30 of the turbine generator 10B acquired by the pressure ratio information acquisition unit 52 is P When the pressure ratio indicated by (i.e., the above-mentioned ratio PBi / PBo) is within the range of 3 to 4, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10B to be 8500 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 60% and the pressure ratio of 3 to 4 in the correlation information T referenced by the correlation information reference unit 58. Also, in the operating unit number skip mode described with reference to Figs. 5A to 5E, L The operating load of the plant 2 indicated by is 60%, and the pressure ratio information S of the turbine 30 of the turbine generator 10C acquired by the pressure ratio information acquisition unit 52 is P If the pressure ratio indicated by (i.e., the above-mentioned ratio PCi / PCo) is a value within the range of 3 to 4, the rotation speed determination unit 60 determines the rotation speed of the turbine 30 of the turbine generator 10C to be 8500 (rpm), which is the rotation speed of the turbine 30 determined by the operating load of 60% and the pressure ratio of 3 to 4 in the correlation information T referenced by the correlation information reference unit 58.

[0045] The effects of the plant 2 will be described below with reference to Figures 7 and 8. Figure 7 is a diagram showing the relationship between the load on the turbine generator and the internal efficiency of the turbine, with the solid line graph showing the case where the turbine is operated at variable speed (where the turbine speed is reduced as the turbine pressure ratio decreases), and the dashed line graph showing the case where the turbine is operated at fixed speed (where the turbine speed is controlled to a constant value regardless of the turbine pressure ratio).

[0046] As shown in FIG. 7, when the turbine is operated at variable speed, it is possible to suppress the deterioration of turbine performance due to a decrease in the turbine pressure ratio (a decrease in the load on the turbine generator) even when the turbine is operated at partial load, compared to when the turbine is operated at fixed speed, and it is also possible to suppress the deterioration of the turbine's internal efficiency.

[0047] Furthermore, the internal efficiency of the turbine increases as the speed ratio U / C0, which is the ratio between the peripheral speed U of the turbine rotor blades and the fluid velocity C0 of the fluid flowing into the turbine rotor blades, approaches the optimal speed ratio (a preset design speed ratio). However, the fluid velocity C0 decreases as the turbine pressure ratio decreases. Meanwhile, there is no fixed correlation between the speed ratio U / C0 and the pressure difference across the turbine. Therefore, by controlling the rotation speed of the turbine 30 based on pressure ratio information of the turbine 30, as in the plant 2, the rotation speed of the turbine 30 can be controlled so that the speed ratio U / C0 approaches the optimal speed ratio (design speed ratio), compared to the Rankine cycle system described in Patent Document 2, in which the turbine rotation speed is changed in accordance with the pressure difference between the inlet and outlet pressures of the turbine. Therefore, compared to the configuration described in Patent Document 1, the decrease in the internal efficiency of the turbine 30 can be suppressed even when the turbine 30 is operated at partial load.

[0048] As an additional effect, variable speed operation of the turbine 30 allows the turbine generator 10 to maintain power generation even at a smaller pressure ratio in the turbine 30, thereby expanding the operable range of the turbine generator 10 and enabling it to be put into service (start providing power) sooner. Furthermore, lowering the rotational speed of the turbine 30 when operating the turbine 30 at partial load is also effective in reducing windage loss, which contributes to reducing losses (improving performance) associated with partial load operation of the turbine 30. Furthermore, starting the turbine generator 10 at a rotational speed lower than conventionally reduces losses due to windage loss, thereby reducing the starting power of the turbine generator 10.

[0049] Furthermore, in the plant 2, the number of operating turbine generators 10 changes depending on the operating load of the plant 2, so the fluid velocity C0 changes not only depending on the pressure ratio of the turbine 30 but also on the operating load of the plant 2. For this reason, as described above, the operating load information S L and the pressure ratio information S acquired by the pressure ratio information acquisition unit 52. P Based on this, by controlling the rotation speed of the turbine 30 of each of the plurality of turbine generators 10A, 10B, 10C so that the speed ratio U / C0 approaches the optimum speed ratio (design speed ratio), it is possible to suppress a decrease in turbine performance even if the operating load of the plant 2 and the pressure ratio of each of the turbines 30 of the plurality of turbine generators 10A, 10B, 10C change, and it is also possible to suppress a decrease in the internal efficiency of the turbine 30.

[0050] Furthermore, by using the correlation information T that associates the pressure ratio range of the turbine 30 with the rotation speed of the turbine 30 for each operating load of the plant 2 as the correlation information T, simpler control can be performed without continuously changing the rotation speed of the turbine 30. Furthermore, hunting can be suppressed.

[0051] In addition, in a first case where the operating load of the plant 2 is between the maximum load and a first predetermined load L1, the turbine control unit 54 uniformly reduces the loads of the plurality of turbine generators 10A, 10B, 10C as the operating load of the plant 2 decreases, and in a second case where the operating load of the plant 2 is equal to or less than the first predetermined load L1, the turbine control unit 54 reduces the number of operating turbine generators 10 compared to the first case. P Since the efficiency reduction associated with partial load operation of the turbine 30 can be suppressed by controlling the rotation speed of the turbine 30 based on the above, it is possible to continue operating all of the turbine generators 10 until the load of the plant 2 reaches a lower load range (without reducing the number of operating turbine generators 10) compared to the case of fixed-speed operation in which the rotation speed of the turbine 30 is fixed. This reduces the frequency of changes in the number of operating turbine generators 10. This reduces the burden on the operator for controlling the number of operating turbine generators 10, and also reduces the risk of plant fluctuations associated with changes in the number of operating turbine generators 10 (for example, the risk of fluctuations in the amount of LNG evaporated in the organic medium condenser 12).

[0052] Figure 8 is a diagram showing the relationship between the operating load of the plant 2 and the internal efficiency of the turbine 30 during operation, with the solid line graph representing the case where variable speed operation of each turbine 30 of the multiple turbine generators 10A, 10B, and 10C is performed in the above-mentioned continuous operating unit mode (where the rotation speed of the turbine 30 is reduced as the pressure ratio of the turbine 30 decreases), the dashed line graph representing the case where variable speed operation of each turbine 30 of the multiple turbine generators 10A, 10B, and 10C is performed in the above-mentioned skip operating unit mode (where the rotation speed of the turbine 30 is reduced as the pressure ratio of the turbine decreases), and the dashed line graph representing the case where fixed speed operation of each turbine 30 of the multiple turbine generators 10A, 10B, and 10C is performed as a comparative example.

[0053] In the example shown in Fig. 8, the first predetermined load L1 that determines the timing at which the number of operating turbine generators 10 is changed from three to two in the continuous number of operating units mode is the same as the load that determines the timing at which the number of operating turbine generators 10 is changed from three to two when the turbine 30 is operated at a fixed speed (comparative example). In addition, the second predetermined load L2 that determines the timing at which the number of operating turbine generators 10 is changed from two to one in the continuous number of operating units mode is the same as the load that determines the timing at which the number of operating turbine generators 10 is changed from two to one when the turbine 30 is operated at a fixed speed (comparative example). In the example shown in Fig. 8, the third predetermined load L3 that determines the timing at which the number of operating turbine generators 10 is changed from three to one in the skip number of operating units mode is the same as the second predetermined load L2 that determines the timing at which the number of operating turbine generators 10 is changed from two to one in the continuous number of operating units mode.

[0054] As shown in Fig. 8, in both the continuous number of operating units mode and the skip number of operating units mode, for each of the multiple turbine generators 10A, 10B, 10C, variable speed operation of the turbine 30 is performed so that the rotation speed of the turbine 30 decreases as the pressure ratio of the turbine 30 decreases, which makes it possible to suppress a decrease in the internal efficiency of the operating turbine 30 in the process of reducing the load on the plant 2, compared to the comparative example in which fixed speed operation of the turbine 30 is performed. Furthermore, the continuous number of operating units mode can more effectively suppress a decrease in the internal efficiency of the operating turbine 30 in the intermediate load range of the plant 2 than the skip number of operating units mode.

[0055] On the other hand, in plant 2, in order to ensure the stability and economy of the amount of LNG evaporated (the amount of natural gas supplied) in the organic medium condenser 12, plant 2 is basically operated at a high load, and therefore operation at an intermediate load is performed relatively infrequently. For this reason, by operating plant 2 in the operating unit number skip mode, it is possible to suppress a decrease in the power generation efficiency of the turbine generator 10 while ensuring the stability of the amount of LNG evaporated (the amount of natural gas supplied). Furthermore, the operating unit number skip mode reduces the frequency of changes in the number of operating turbine generators 10, thereby reducing the burden on the operator for controlling the number of operating turbine generators 10 and reducing the risk of plant fluctuations associated with changes in the number of operating turbine generators 10 (for example, the risk of fluctuations in the amount of LNG evaporated in the organic medium condenser 12).

[0056] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0057] For example, in the above-described embodiment, the plant 2 is provided with three turbine generators 10A, 10B, and 10C, but the number of turbine generators 10 provided in the plant 2 is not limited, and it is sufficient that the plant 2 is provided with at least one turbine generator 10. Furthermore, when the number of turbine generators 10 provided in the plant 2 is one, the rotation speed determination unit 60 uses the operating load information S indicating the operating load of the plant 2 to determine the rotation speed of the turbine 30. L When the plant 2 includes one turbine generator 10, correlation information U indicating the correlation between the pressure ratio of the turbine 30 in the turbine generator 10 and the rotation speed of the turbine 30 may be used instead of correlation information T used when the plant 2 includes a plurality of turbine generators 10, and the rotation speed determination unit 60 may be configured to determine the rotation speed of the turbine 30 based on the pressure ratio information of the turbine 30 acquired by the pressure ratio information acquisition unit 52 and the correlation information U referenced by the correlation information reference unit 58.

[0058] In addition, the operating number determination unit 56 may be configured to be able to change each of the first predetermined load L1, the second predetermined load L2, and the third predetermined load L3 that determine the timing for changing the number of operating turbine generators 10, and these loads L1, L2, and L3 may be changed in accordance with, for example, deterioration of the turbine generators 10 over time, the season, changes in the operating method of the organic medium condenser 12, etc.

[0059] Furthermore, in a case where the plant 2 is equipped with a plurality of turbine generators 10, and the number of turbine generators 10 equipped in the plant 2 is n (where n is an integer greater than or equal to 2), the turbine control unit 54 may, in the continuous operating number mode, operate n turbine generators 10 in a first case where the operating load of the plant 2 is a load between the maximum load and a first predetermined load L1, and when the operating load of the plant 2 changes from the first case to a second case where the operating load is greater than a second predetermined load L2 but less than or equal to the first predetermined load L1, continue operating (n-1) turbine generators 10 and suspend operation of one turbine generator 10.

[0060] Furthermore, in the case where the plant 2 is equipped with a plurality of turbine generators 10, the number of turbine generators 10 equipped in the plant 2 is defined as n (where n is an integer greater than or equal to 2), and m is defined as an integer greater than or equal to 2, and in the operating unit number skip mode, the turbine control unit 54 may operate n turbine generators 10 when the operating load of the plant 2 is between the maximum load and a third predetermined load L3, and may continue operating (nm) turbine generators 10 and suspend operation of m turbine generators 10 when the operating load of the plant 2 becomes equal to or less than the third predetermined load L3.

[0061] Furthermore, although the operating number determination unit 56 is configured to be able to execute the continuous operating number mode and the skip operating number mode, the operating number determination unit 56 may be configured to be able to execute only one of the continuous operating number mode and the skip operating number mode (only the continuous operating number mode or only the skip operating number mode).

[0062] Furthermore, since a change in the temperature of the seawater flowing through the seawater line 14 affects the outlet pressure of the turbine 30, the turbine control unit 54 L and pressure ratio information S of the plurality of turbine generators 10 P In addition, the number of operating turbine generators 10 and the rotation speed of the turbine 30 may be determined taking into consideration the temperature of the seawater flowing through the seawater line 14 as well.

[0063] The contents described in each of the above embodiments can be understood, for example, as follows.

[0064] [1] An organic Rankine cycle power plant according to at least one embodiment of the present disclosure (e.g., the organic Rankine cycle power plant 2 described above) includes: a circulation line (for example, the above-mentioned circulation line 4) through which the organic medium circulates; an evaporator (for example, the organic medium evaporator 8 described above) that is provided in the circulation line and evaporates the organic medium by heat exchange with a heat medium; at least one turbine generator (e.g., the above-mentioned turbine generator 10) including a turbine (e.g., the above-mentioned turbine 30) driven by the organic medium evaporated in the evaporator and a generator (e.g., the above-mentioned generator 32) coupled to the turbine; a condenser (e.g., the organic medium condenser 12 described above) that condenses the organic medium leaving the turbine by heat exchange with liquefied natural gas; a pressure ratio information acquisition unit (for example, the above-mentioned pressure ratio information acquisition unit 52) ​​configured to acquire pressure ratio information indicating a pressure ratio of the turbine; a turbine control unit (for example, the above-described turbine control unit 54) configured to control the rotation speed of the turbine based on the pressure ratio information acquired by the pressure ratio information acquisition unit; Equipped with.

[0065] According to the organic Rankine cycle power plant described in [1] above, compared to a case where the turbine rotation speed is controlled to a constant value (e.g., rated rotation speed) regardless of the turbine pressure ratio, the deterioration of turbine performance due to changes in the turbine pressure ratio can be suppressed even when the turbine is operated at a partial load, thereby suppressing a decrease in the turbine's internal efficiency. Furthermore, the turbine's internal efficiency increases as the speed ratio U / C0, which is the ratio between the turbine blade peripheral speed U and the fluid velocity C0 of the fluid flowing into the turbine blade, approaches the optimal speed ratio (design speed ratio). However, the fluid velocity C0 is affected by the turbine pressure ratio, and decreases as the turbine pressure ratio decreases. Meanwhile, there is no fixed correlation between the speed ratio U / C0 and the turbine pressure difference. Therefore, by controlling the turbine rotation speed based on the turbine pressure ratio information as described in (1) above, the turbine rotation speed can be controlled so that the speed ratio U / C0 approaches the optimal speed ratio (design speed ratio), compared to a case where the turbine rotation speed is changed according to the pressure difference between the turbine's inlet pressure and its outlet pressure, as in the Rankine cycle system described in Patent Document 2. Therefore, compared to the configuration described in Patent Document 1, it is possible to suppress a decrease in the internal efficiency of the turbine even when the turbine is operated at a partial load.

[0066] In addition to the above effects, the turbine generator can maintain power generation even at a smaller pressure ratio in the turbine, thereby expanding the operational range of the turbine generator and enabling it to be put into service sooner (start providing power). Furthermore, lowering the rotational speed when operating the turbine at partial load also has the effect of reducing windage loss, which contributes to reducing losses (improving performance) associated with partial load operation of the turbine. Furthermore, starting the turbine generator at a lower rotational speed than before reduces losses due to windage loss, thereby reducing the starting power of the turbine generator.

[0067] [2] In some embodiments, in the organic Rankine cycle power plant according to [1] above, The organic Rankine cycle power generation plant further includes an operating load information acquisition unit (for example, the operating load information acquisition unit 50) configured to acquire operating load information indicating an operating load of the organic Rankine cycle power generation plant, the at least one turbogenerator is a plurality of turbogenerators (e.g., the plurality of turbogenerators 10A, 10B, and 10C described above); The turbine control unit is configured to control the rotation speed of the turbine of each of the plurality of turbine generators based on the operating load information acquired by the operating load information acquisition unit and the pressure ratio information acquired by the pressure ratio information acquisition unit.

[0068] When an organic Rankine cycle power plant includes a plurality of turbine generators, the number of operating turbine generators among the plurality of turbine generators changes depending on the operating load of the plant, and therefore the fluid velocity C0 changes depending not only on the turbine pressure ratio but also on the operating load of the plant. Therefore, as described in [2] above, by controlling the rotation speed of each turbine of the plurality of turbine generators so that the speed ratio U / C0 approaches an optimal speed ratio (design speed ratio) based on the operating load information acquired by the operating load information acquisition unit and the pressure ratio information acquired by the pressure ratio information acquisition unit, it is possible to suppress a decrease in turbine performance even if the operating load of the plant and the turbine pressure ratio change, and it is possible to suppress a decrease in the internal efficiency of the turbine.

[0069] [3] In some embodiments, in the organic Rankine cycle power plant described in [2] above, The turbine control unit a correlation information reference unit (for example, the above-mentioned correlation information reference unit 58) configured to reference correlation information indicating a correlation between the operating load, the pressure ratio of the turbine, and the rotation speed of the turbine for each of the plurality of turbine generators; a rotation speed determination unit (for example, the above-described rotation speed determination unit 60) configured to determine a rotation speed of the turbine for each of the plurality of turbine generators based on the operating load information acquired by the operating load information acquisition unit, the pressure ratio information acquired by the pressure ratio information acquisition unit, and the correlation information referenced by the correlation information reference unit, The turbine control unit is configured to control the rotation speed of the turbine of each of the plurality of turbine generators to the rotation speed determined by the rotation speed determination unit.

[0070] According to the organic Rankine cycle power plant described in [3] above, by using correlation information that associates the range of the turbine pressure ratio with the turbine rotation speed for each operating load of the plant as the correlation information, it is possible to perform simpler control without continuously changing the turbine rotation speed, and also to suppress hunting.

[0071] [4] In some embodiments, in the organic Rankine cycle power plant according to any one of [1] to [3] above, The turbine control unit is configured to uniformly reduce the loads of the plurality of turbine generators as the operating load decreases in a first case in which the operating load of the organic Rankine cycle power generation plant is a load between a maximum load and a predetermined load, and to reduce the number of operating turbine generators of the plurality of turbine generators compared to the first case in a second case in which the operating load is equal to or less than the predetermined load.

[0072] According to the organic Rankine cycle power plant described in [4] above, the efficiency decrease due to partial load operation of the turbine can be suppressed by controlling the turbine rotation speed based on the turbine pressure ratio information. Therefore, compared to when the turbine rotation speed is fixed, it is possible to continue operating all the turbine generators until the plant load reaches a lower range (without reducing the number of operating turbine generators). This reduces the frequency of changes in the number of operating turbine generators. Therefore, it is possible to reduce the burden on operators for controlling the number of operating turbine generators and also to reduce the risk of plant fluctuations in the organic Rankine cycle power plant due to changes in the number of operating turbine generators (for example, the risk of fluctuations in the amount of evaporation of liquefied natural gas in the condenser).

[0073] [5] In some embodiments, in the organic Rankine cycle power plant described in [4] above, the plurality of turbine generators is n turbine generators, The turbine control unit is configured to operate n of the turbine generators in the first case, and when the first case changes to the second case, to continue operating (n-1) of the turbine generators and to suspend operation of one of the turbine generators.

[0074] According to the organic Rankine cycle power generation plant described in [5] above, the load reduction of the (n-1) turbine generators that continue to operate can be suppressed by the amount of the turbine generators that have been suspended, and therefore the reduction in the internal efficiency of the turbines of the (n-1) turbine generators that continue to operate can be suppressed.

[0075] [6] In some embodiments, in the organic Rankine cycle power plant described in [4] above, the plurality of turbine generators is n turbine generators, When an integer m greater than or equal to 2 is defined, the turbine control unit is configured to operate n of the turbine generators in the first case, and when the first case changes to the second case, to continue operating (nm) of the turbine generators and to suspend operation of m of the turbine generators.

[0076] In an organic Rankine cycle power plant that uses the cold energy of liquefied natural gas, in order to ensure the stability and economy of the evaporation rate of liquefied natural gas (natural gas supply rate), the plant is generally operated at a high load all the time, with moderate load operation being relatively rare. Therefore, as described in [6] above, when the situation changes from the first case to the second case, the operation of (nm) turbine generators is continued and the operation of m turbine generators is suspended, thereby ensuring the stability of the evaporation rate of liquefied natural gas (natural gas supply rate) and suppressing a decrease in the power generation efficiency of the turbine generators. [Explanation of symbols]

[0077] 2. Organic Rankine cycle power plant 4 Circulation Line 4a, 4b, 4c branch lines 5. Bypass Line 6. Pump 8. Evaporator 10, 10A, 10B, 10C Turbine Generator 12 Condenser 14 Seawater Line 15 Branch Line 16 Tank 18 LNG lines 19 Flow control valve 20 Trim heater 22 Bypass valve 30 Turbine 32 Generator 34 Inverter device 36 Converter 38 Inverter 40A, 40B, 40C, 42A, 42B, 42C pressure gauges 45 Flow meter 50 Driving load information acquisition unit 52 Pressure ratio information acquisition unit 54 Turbine control section 56 Operational Unit Number Determination Department 58 Correlation information reference section 60 Rotation speed determination unit 90 Control device 91 processors 92 RAM 93 ROM 94 HDD 95 Bus 96 Input I / F 98 Output I / F

Claims

1. 1. An organic Rankine cycle power plant comprising: a circulation line through which the organic medium circulates; an evaporator provided in the circulation line for evaporating the organic medium by heat exchange with a heat medium; at least one turbine generator including a turbine driven by the organic medium evaporated in the evaporator and a generator connected to the turbine; a condenser for condensing the organic medium leaving the turbine by heat exchange with liquefied natural gas; a pressure ratio information acquisition unit configured to acquire pressure ratio information indicating a pressure ratio of the turbine; a turbine control unit configured to control a rotation speed of the turbine based on the pressure ratio information acquired by the pressure ratio information acquisition unit; An organic Rankine cycle power plant comprising:

2. an operating load information acquisition unit configured to acquire operating load information indicating an operating load of the organic Rankine cycle power generation plant; the at least one turbo-generator is a plurality of turbo-generators; 2. The organic Rankine cycle power generation plant according to claim 1, wherein the turbine control unit is configured to control a rotation speed of the turbine of each of the plurality of turbine generators based on the operating load information acquired by the operating load information acquisition unit and the pressure ratio information acquired by the pressure ratio information acquisition unit.

3. The turbine control unit a correlation information reference unit configured to reference correlation information indicating a correlation between the operating load, the pressure ratio of the turbine, and the rotation speed of the turbine for each of the plurality of turbine generators; a rotation speed determination unit configured to determine a rotation speed of the turbine for each of the plurality of turbine generators based on the operating load information acquired by the operating load information acquisition unit, the pressure ratio information acquired by the pressure ratio information acquisition unit, and the correlation information referenced by the correlation information reference unit; Including, The organic Rankine cycle power plant according to claim 2 , wherein the turbine control unit is configured to control the rotation speed of the turbine of each of the plurality of turbine generators to the rotation speed determined by the rotation speed determination unit.

4. 3. The organic Rankine cycle power plant according to claim 2, wherein the turbine control unit is configured to uniformly reduce the loads of the plurality of turbine generators as the operating load decreases in a first case in which the operating load of the organic Rankine cycle power plant is a load between a maximum load and a predetermined load, and to reduce the number of operating turbine generators of the plurality of turbine generators compared to the first case in a second case in which the operating load is equal to or less than the predetermined load.

5. the plurality of turbine generators is n turbine generators, 5. The organic Rankine cycle power plant according to claim 4, wherein the turbine control unit is configured to operate n of the turbine generators in the first case, and when the first case changes to the second case, to continue operation of (n-1) of the turbine generators and to suspend operation of one of the turbine generators.

6. the plurality of turbine generators is n turbine generators, 5. The organic Rankine cycle power plant according to claim 4, wherein, when m is defined as an integer equal to or greater than 2, the turbine control unit operates n of the turbine generators in the first case, and, when the first case changes to the second case, continues operation of (n-m) of the turbine generators and suspends operation of m of the turbine generators.

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