Non-condensable gas reduction system

Abstract

This disclosure provides a non-condensable gas reduction system that efficiently processes non-condensable gases when the amount of non-condensable gases emitted from a geothermal power plant fluctuates. [Solution] A non-condensable gas reduction system for a geothermal power plant, which returns non-condensable gas that remains uncondensed when cooled in a condenser in a first gas contained in the geothermal fluid that springs from a production well back to a reinjection well, comprising: a pump that pressurizes a first liquid sent to the reinjection well; an ejector driven by the first liquid that induces the non-condensable gas and discharges a second liquid which is a mixture of the first liquid and the non-condensable gas; and a compressor that pressurizes the non-condensable gas supplied from the condenser to the ejector.

Description

Technical Field

[0001] The present disclosure relates to a non-condensable gas reduction system.

Background Art

[0002] Patent Document 1 discloses a method for disposing of non-condensable gas generated in a geothermal power generation facility, in which the non-condensable gas generated in a condenser provided downstream of a steam turbine is injected into a reduction well for hot water reduction, and is reduced underground together with the reduced hot water.

[0003] Patent Document 2 discloses a geothermal power generation plant including a reduction water flow path for transporting reduction water to a reduction well, a gas extraction device for extracting gas from a condenser, and a gas flow path for supplying the gas extracted from the condenser to the reduction water flow path and mixing it into the reduction water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As disclosed in Patent Document 1 and Patent Document 2, in geothermal power generation, non-condensable gases such as carbon dioxide or hydrogen sulfide are reduced to a reduction well. The discharge amount of non-condensable gas in a geothermal power generation plant varies due to influences such as planned changes in power generation amount or attenuation of steam production during long-term operation. It is required to process in response to fluctuations in the discharge amount of non-condensable gas in a geothermal power generation plant.

[0006] The present disclosure provides a non-condensable gas reduction system that efficiently processes non-condensable gas when the discharge amount of non-condensable gas in a geothermal power generation plant fluctuates. [Means for solving the problem]

[0007] This disclosure provides a non-condensable gas reduction system for a geothermal power plant, which returns non-condensable gas, which remains uncondensed when cooled in a condenser, to a reinjection well in a first gas contained in the geothermal fluid that springs from a production well, the system comprising: a pump for pressurizing a first liquid sent to the reinjection well; an ejector driven by the first liquid for inducing the non-condensable gas and for discharging a second liquid which is a mixture of the first liquid and the non-condensable gas; and a compressor for pressurizing the non-condensable gas supplied from the condenser to the ejector. [Effects of the Invention]

[0008] According to the non-condensable gas reduction system disclosed herein, non-condensable gases can be efficiently processed when the amount of non-condensable gases emitted from a geothermal power plant fluctuates. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram showing the configuration of the ejector in the non-condensable gas reduction system according to the first embodiment. [Figure 3] Figure 3 is a schematic diagram showing the configuration of the compression section of the non-condensable gas reduction system according to the first embodiment. [Figure 4] Figure 4 is a flowchart illustrating the processing of the non-condensable gas reduction system according to the first embodiment. [Figure 5] Figure 5 is a diagram illustrating the processing of the non-condensable gas reduction system according to the first embodiment. [Figure 6] Figure 6 is a schematic diagram showing the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the second embodiment. [Figure 7] Figure 7 is a flowchart illustrating the processing of the non-condensable gas reduction system according to the second embodiment. [Figure 8] Figure 8 illustrates a first example of the processing of a non-condensable gas reduction system according to the second embodiment. [Figure 9] Figure 9 illustrates the processing of the non-condensable gas reduction system in the first reference example. [Figure 10] Figure 10 illustrates a second example of the processing of the non-condensable gas reduction system according to the second embodiment. [Figure 11] Figure 11 illustrates the processing of a non-condensable gas reduction system in the second reference example. [Figure 12] Figure 12 is a schematic diagram showing a modified configuration of the compression section of the noncondensable gas reduction system according to the present disclosure. [Figure 13] Figure 13 is a schematic diagram showing a modified configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the second embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the attached drawings. However, this disclosure is not limited to these examples, and all modifications are intended to be included in the meaning and scope equivalent to the claims, as indicated by the claims.

[0011] In addition, regarding the descriptions and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. Furthermore, for ease of understanding, the scale of each part in the drawings may differ from that of the actual parts.

[0012] The non-condensable gas reduction system according to an embodiment of the present disclosure will be described. The non-condensable gas reduction system according to an embodiment of the present disclosure is a non-condensable gas reduction system that returns, in a geothermal power plant, non-condensable gas remaining without being condensed when cooled in a condenser, in a first gas contained in geothermal fluid gushing out from a production well, to a reinjection well. The non-condensable gas reduction system according to an embodiment of the present disclosure includes a pump that pressurizes a first liquid sent to the reinjection well, and an ejector that is driven by the first liquid, attracts non-condensable gas, and discharges a second liquid in which the first liquid and the non-condensable gas are mixed. Further, the non-condensable gas reduction system according to an embodiment of the present disclosure further includes a compressor that pressurizes non-condensable gas supplied from the condenser to the ejector.

[0013] ≪First Embodiment≫ The non-condensable gas reduction system according to the first embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the configuration of a geothermal power plant 1 including a non-condensable gas reduction system 50 which is an example of the non-condensable gas reduction system according to the first embodiment.

[0014] The geothermal power plant 1 includes a gas-liquid separator 10, a power generation unit 20, a condenser 30, a cooling unit 40, a non-condensable gas reduction system 50, and a control unit 60. The geothermal power plant 1 is a geothermal power plant using a so-called flash-type geothermal power generation method. Further, the geothermal power plant 1 includes valves 81 and 82, and a pump 91.

[0015] [Gas-Liquid Separator 10] The gas-liquid separator 10 separates geothermal fluid GF ejected from the production well PWL into steam ST and hot water HW. The geothermal fluid GF ejected from the production well PWL is passed or blocked by the valve 81. The steam ST discharged from the gas-liquid separator 10 is sent to the power generation unit 20. The hot water HW discharged from the gas-liquid separator 10 is discharged to the reinjection well RWL. A pressure gauge 71 described later measures the pressure of the hot water HW.

[0016] Here, the steam ST is not pure water vapor, but contains gases discharged from the production well PWL, such as carbon dioxide, hydrogen sulfide, and the like.

[0017] [Power generation unit 20] The power generation unit 20 generates electricity using steam ST. The power generation unit 20 comprises a turbine 21 and a generator 22. The turbine 21 is rotated by the steam ST. More specifically, the turbine 21 rotates due to the pressure difference between the pressure from the steam ST and the pressure reduced by the condensation of water vapor contained in the steam ST in the condenser 30. The generator 22 is connected to the turbine 21. When the turbine 21 rotates, the rotating shaft of the generator 22 rotates and generates electricity. The electricity generated by the generator 22 is supplied to the outside.

[0018] [Condenser 30] The condenser 30 cools the steam ST discharged from the turbine 21 with coolant CW, more specifically coolant CW1, supplied from the cooling unit 40. The condenser 30 is a so-called surface contact condenser. The condenser 30 performs heat exchange between the coolant CW1 and the steam ST. By performing heat exchange between the coolant CW1 and the steam ST, the steam ST is cooled. As the steam ST is cooled in the condenser 30, it condenses into water. In the surface contact condenser 30, for example, the coolant CW1 flows inside the piping of the heat exchanger, so the coolant CW1 does not come into direct contact with the steam ST.

[0019] Non-condensable gases (NCGs) such as carbon dioxide and hydrogen sulfide contained in the steam ST accumulate at the top of the condenser 30. When non-condensable gases NCG accumulate, the pressure in the condenser 30 increases. When the pressure in the condenser 30 increases, the driving force for rotating the turbine 21 decreases. When the driving force for rotating the turbine 21 decreases, the power generation efficiency of the power generation unit 20 decreases. Therefore, it is desirable to discharge the non-condensable gases NCG accumulated in the condenser 30 from the condenser 30.

[0020] In geothermal power plant 1, the non-condensable gas (NCG) that accumulates in the condenser 30 is drawn in by the non-condensable gas reduction system 50 and discharged into the reinjection well (RWL).

[0021] [Cooling section 40] The cooling unit 40 supplies coolant CW to cool the steam ST in the condenser 30. The cooling unit 40 is, for example, a cooling tower. The coolant CW1 cooled in the cooling unit 40 is sent to the condenser 30 by the pump 91. In the condenser 30, the coolant CW2 whose temperature has risen due to heat exchange with the steam ST returns to the cooling unit 40 to be cooled.

[0022] For example, if the cooling unit 40 is a cooling tower, the coolant CW2 is cooled by heat exchange with the atmosphere. When cooling is performed by heat exchange between the coolant CW2 and the atmosphere, atmospheric components such as nitrogen and oxygen contained in the atmosphere are mixed into the coolant CW. The atmospheric components mixed into the coolant CW are then mixed into the coolant CW1 and the coolant CWa described later.

[0023] [Non-condensable gas reduction system 50] The non-condensable gas reduction system 50 draws in and discharges non-condensable gas NCG from the condenser 30. The non-condensable gas reduction system 50 comprises an ejector 54, a compression unit 56, a control device 58, pressure gauges 71, 72, and 73, a flow meter 75, a valve 83, and a pump 55. The ejector 54 is driven by coolant CW, more specifically coolant CWa, which is a part of coolant CW1. Coolant CWa is pumped by the pump 55. The ejector 54 discharges a mixture MW, which is a mixture of non-condensable gas NCG and coolant CWa.

[0024] (Ejector 54) The structure of the ejector 54 will now be described. Figure 2 is a schematic diagram of the configuration of the ejector 54 provided in the noncondensable gas reduction system 50, which is an example of a noncondensable gas reduction system according to the first embodiment.

[0025] The ejector 54 comprises an induction section 51, a drive nozzle 52, and an expansion section 53. The induction section 51 has an induction port 51a. Non-condensable gas NCG is drawn in from the induction port 51a. The drive nozzle 52 is inserted into the induction section 51. Pressurized coolant CWa is supplied to the drive port 52a of the drive nozzle 52 by the pump 55. As the high-speed coolant CWa is discharged from the tip of the drive nozzle 52, the non-condensable gas NCG present in the induction section 51 is discharged while mixing with the coolant CWa. As the non-condensable gas NCG is discharged, the ejector 54 draws in the non-condensable gas NCG.

[0026] The ejector 54 mixes the non-condensable gas NCG and the coolant CWa and discharges the mixed liquid MW through the expanded pipe section 53.

[0027] In ejector 54, the non-condensable gas NCG and coolant CWa are mixed and discharged, and the resulting mixture MW is sent to the reinjection well RWL.

[0028] The ejector 54 is installed on the ground. Installing the ejector 54 on the ground makes maintenance of the ejector 54 easier. Furthermore, by installing multiple ejectors, maintenance can be performed without shutting down the system.

[0029] (Compression section 56) The compression unit 56 pressurizes the non-condensable gas NCG supplied from the condenser 30 to the ejector 54. The compression unit 56 pressurizes the non-condensable gas NCG discharged from the condenser 30 and supplies it to the ejector 54.

[0030] The details of the compression section 56 will now be described. Figure 3 is a schematic diagram of the configuration of the compression section 56 included in a noncondensable gas reduction system 50, which is an example of a noncondensable gas reduction system according to the first embodiment.

[0031] The compression section 56 has a main flow path 56m and a bypass flow path 56n. The compression section 56 is equipped with a check valve 56a in the main flow path 56m. The check valve 56a causes the non-condensable gas NCG to flow in one direction, specifically from the condenser 30 to the ejector 54. The compression section 56 is also equipped with a compressor 56b in the bypass flow path 56n. The compressor 56b is, for example, a positive displacement or turbo compressor.

[0032] The rotational speed of the compressor 56b is controlled by the inverter 56c. The inverter 56c is controlled by the control device 58. By controlling the rotational speed of the compressor 56b, the flow rate of the non-condensable gas NCG discharged by the compressor 56b is controlled.

[0033] The non-condensable gas (NCG) discharged from the condenser 30 passes through the main channel 56m when the compressor 56b is stopped. When the compressor 56b is operating, the non-condensable gas (NCG) discharged from the condenser 30 passes through the main channel 56m and the bypass channel 56n. When the compressor 56b is operating, the non-condensable gas (NCG) discharged from the condenser 30 is pressurized and discharged to the ejector 54.

[0034] (Flowmeter 75) The flow meter 75 measures the flow rate (main steam flow rate) of steam ST discharged from the gas-liquid separator 10.

[0035] (Control device 58) The control device 58 is primarily composed of a computer, including, for example, a processor, memory or other storage devices, auxiliary storage devices, and an external input / output interface device. The processor is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an MPU (Micro Processing Unit). The control device 58 may also be, for example, a programmable logic controller (PLC).

[0036] During power generation, if the pressure P1 at the pressure gauge 71 becomes higher than the pressure P2 at the pressure gauge 73, the control device 58 controls the valve 83 to close in order to prevent hot water HW from flowing into the condenser 30. The valve 83 is located in the flow path of non-condensable gas NCG between the condenser 30 and the ejector 54. The pressure P1 at the pressure gauge 71 is the pressure of the hot water HW, and the pressure P2 at the pressure gauge 73 is the discharge pressure of the pump 55.

[0037] The control device 58 may also monitor the pressure of the non-condensable gas NCG using the pressure gauge 72.

[0038] The process performed by the control device 58 will now be described. The control device 58 controls the flow rate (first flow rate) of the non-condensable gas NCG supplied from the condenser 30 to the ejector 54. Figure 4 is a flowchart illustrating the process of a non-condensable gas reduction system 50, which is an example of a non-condensable gas reduction system according to the first embodiment.

[0039] (Step S1) The control device 58 obtains the flow rate (main steam flow rate) of steam ST discharged from the gas-liquid separator 10 from the flow meter 75. The control device 58 controls the flow meter 75 to measure the flow rate of steam ST discharged from the gas-liquid separator 10. Then, the control device 58 obtains the measured flow rate (main steam flow rate) of steam ST discharged from the gas-liquid separator 10 from the flow meter 75.

[0040] (Step S2) Next, the control device 58 calculates the non-condensable gas flow rate from the main steam flow rate obtained in step S1. The control device 58 calculates the non-condensable gas flow rate from the main steam flow rate using data on the relationship between the main steam flow rate and the non-condensable gas flow rate obtained, for example, during periodic inspections.

[0041] (Step S3) Next, the control device 58 calculates the non-condensable gas discharge rate from the non-condensable gas flow rate calculated in step S2. The non-condensable gas discharge rate is, for example, the ratio of the non-condensable gas flow rate calculated in step S2 to the maximum discharge rate of the non-condensable gas NCG designed for the non-condensable gas reduction system 50, which is set to 100%.

[0042] (Step S4) Next, the control device 58 controls the compression unit 56 to perform supercharging control based on the non-condensable gas discharge rate calculated in step S3. Figure 5 is a diagram illustrating the process of a non-condensable gas reduction system 50, which is an example of a non-condensable gas reduction system according to the first embodiment.

[0043] In Figure 5, the horizontal axis represents the non-condensable gas emission rate Qs calculated in step S3, and the vertical axis represents the actual treatment amount Qe, which corresponds to the actual flow rate of non-condensable gas NCG discharged. In Figure 5, the horizontal and vertical axes are shown with the design maximum discharge flow rate of non-condensable gas NCG of the non-condensable gas reduction system 50 set to 100%.

[0044] For example, the ejector 54 discharges non-condensable gas NCG at a flow rate corresponding to the discharge rate Q1 while the compression section 56 is not pressurized.

[0045] In Figure 5, range A1 represents the range in which non-condensable gas NCG is discharged by the ejector 54, and range E1 represents the range in which the flow rate of non-condensable gas NCG is increased by operating the compressor 56b. Line L1 represents the line in which the non-condensable gas discharge rate Qs calculated in step S3 is equal to the actual processing amount Qe, which corresponds to the actual flow rate of non-condensable gas NCG discharged. Above line L1 is an excess amount of non-condensable gas to be processed. Above line L1 is an excess supply of coolant CWa used for non-condensable gas processing. In other words, it indicates that the power of the pump 55 is excessive.

[0046] The control device 58 controls the compressor 56b to stop and discharge noncondensable gas NCG when the noncondensable gas discharge rate Qs is less than the discharge rate Q1. Furthermore, the control device 58 controls the compressor 56b to operate and discharge noncondensable gas NCG when the noncondensable gas discharge rate Qs is equal to or greater than the discharge rate Q1. Additionally, when operating the compressor 56b when the noncondensable gas discharge rate Qs is equal to or greater than the discharge rate Q1, the control device 58 increases the actual processing amount Qe according to the noncondensable gas discharge rate Qs.

[0047] The non-condensable gas reduction system 50, by comprising an ejector 54 and a compression unit 56, can process non-condensable gas NCG exceeding the capacity of the ejector 54 even if it is discharged in an amount exceeding the capacity of the ejector 54, thanks to the compressor 56b.

[0048] (Step S5) Next, the control device 58 determines whether the main steam flow rate is zero. If the main steam flow rate is zero (YES in step S5), the control device 58 terminates the process. If the main steam flow rate is not zero (NO in step S5), the control device 58 returns to step S1 and repeats the process.

[0049] [Control Unit 60] The control unit 60 controls the entire geothermal power plant 1. The control unit 60 is mainly composed of a computer including, for example, a processor, memory or other storage devices, auxiliary storage devices, and an input / output interface device for external communication. The processor is, for example, a CPU, GPU, or MPU. The control unit 60 may also be, for example, a programmable logic controller.

[0050] The control unit 60 controls the pump 91. When generating power, the control unit 60 controls the pump 91 to start. When stopping power generation, the control unit 60 controls the pump 91 to stop.

[0051] According to the non-condensable gas reduction system of the first embodiment, non-condensable gas can be efficiently processed when the amount of non-condensable gas discharged from a geothermal power plant fluctuates.

[0052] In the noncondensable gas reduction system 50, which is an example of a noncondensable gas reduction system according to the first embodiment, processing was performed based on the flow rate of the noncondensable gas NCG, but the control method is not limited to the example described above. For example, the pressure in the condenser 30 may be measured and the system may be controlled so that the measured pressure in the condenser 30 becomes a predetermined pressure.

[0053] ≪Second Embodiment≫ A non-condensable gas reduction system according to the second embodiment will now be described. The non-condensable gas reduction system according to the second embodiment includes a plurality of ejectors. In other words, the non-condensable gas reduction system according to the second embodiment includes a plurality of ejectors. The control device in the non-condensable gas reduction system according to the second embodiment controls the number of ejectors to be operated.

[0054] The non-condensable gas reduction system according to the second embodiment will be described in detail with reference to the drawings. Figure 6 is a schematic diagram of the configuration of a geothermal power plant 2 equipped with a non-condensable gas reduction system 150, which is an example of a non-condensable gas reduction system according to the second embodiment.

[0055] In the non-condensable gas reduction system 150, which is an example of a non-condensable gas reduction system according to the second embodiment, a detailed explanation of the configuration common to the non-condensable gas reduction system 50 will be omitted here, as it will be referred to in the description of the first embodiment. Similarly, for the geothermal power plant 2, a detailed explanation of the configuration common to the geothermal power plant 1 will be omitted here, as it will be referred to in the description of the first embodiment.

[0056] Geothermal power plant 2 is equipped with a non-condensable gas reduction system 150, replacing the non-condensable gas reduction system 50 in geothermal power plant 1.

[0057] [Non-condensable gas reduction system 150] The non-condensable gas reduction system 150 induces and discharges non-condensable gas (NCG) from the condenser 30. The non-condensable gas reduction system 150 includes ejectors 54a, 54b, and 54c, a compression unit 56, a control device 158, pressure gauges 71, 72a, 72b, 72c, and 73, a flow meter 75, and a pump 55.

[0058] Furthermore, the non-condensable gas reduction system 150 includes a valve 83a (an example of a first valve, the same applies hereinafter) provided in a passage (an example of a first passage, the same applies hereinafter) through which the non-condensable gas supplied to the ejector 54a flows. Furthermore, the non-condensable gas reduction system 150 includes a valve 84a (an example of a second valve, the same applies hereinafter) provided in a passage (an example of a second passage, the same applies hereinafter) through which the coolant CWa supplied to the ejector 54a flows. Similarly, the non-condensable gas reduction system 150 includes a valve 83b provided in a passage (an example of a first passage) through which the non-condensable gas supplied to the ejector 54b flows, and a valve 84b provided in a passage through which the coolant CWa supplied to the ejector 54b flows. Furthermore, the non-condensable gas reduction system 150 includes a valve 83c provided in a passage through which the non-condensable gas supplied to the ejector 54c flows, and a valve 84c provided in a passage through which the coolant CWa supplied to the ejector 54c flows.

[0059] The control device 158 controls the number of ejectors to be operated by opening and closing valves 83a, 83b, 83c, 84a, 84b, and 84c.

[0060] Each of the ejectors 54a, 54b, and 54c is driven by coolant CW, more specifically by coolant CWa, which is a part of coolant CW1. Coolant CWa is pumped by pump 55. Each of the ejectors 54a, 54b, and 54c discharges a mixture MW, which is a mixture of noncondensable gas NCG and coolant CWa.

[0061] Since the configurations of ejectors 54a, 54b, and 54c are the same as those of ejector 54, please refer to the description of ejector 54, and a detailed explanation will be omitted here.

[0062] Furthermore, since the control device 158 has the same configuration as the control device 58 except for the processing content, a detailed explanation will be omitted here.

[0063] The processes performed by the control device 158 will now be described. Figure 7 is a flowchart illustrating the processes of a non-condensable gas reduction system 150, which is an example of a non-condensable gas reduction system according to the second embodiment.

[0064] Steps S1, S2, S3, and S5 are the same as those performed by the control device 58, so a detailed explanation is omitted here.

[0065] (Step S14) The control device 158 controls the number of ejectors 54a, ejectors 54b, and ejectors 54c based on the non-condensable gas emission rate calculated in step S3, and also controls the compression unit 56 to perform supercharging control. Figure 8 is a diagram illustrating the processing of a non-condensable gas reduction system 150, which is an example of a non-condensable gas reduction system according to the second embodiment.

[0066] In Figure 8, the horizontal axis represents the non-condensable gas emission rate Qs calculated in step S3, and the vertical axis represents the actual treatment amount Qe, which corresponds to the actual flow rate of non-condensable gas NCG discharged. In Figure 8, the horizontal and vertical axes are shown with the design maximum discharge flow rate of non-condensable gas NCG of the non-condensable gas reduction system 50 set to 100%.

[0067] Ejectors 54a, 54b, and 54c are assumed to have the same processing capacity. For example, each of ejectors 54a, 54b, and 54c discharges non-condensable gas NCG at a maximum flow rate corresponding to the discharge rate Q21 when the compression unit 56 is not pressurized. When the non-condensable gas NCG is discharged by the three ejectors 54a, 54b, and 54c when the compression unit 56 is not pressurized, the non-condensable gas discharge rate Qs is defined as 100%.

[0068] In Figure 8, range A2 represents the range in which the non-condensable gas NCG is processed by ejector 54a, range B2 represents the range in which the non-condensable gas NCG is processed by ejector 54b, and range C2 represents the range in which the non-condensable gas NCG is processed by ejector 54c. Also in Figure 8, ranges E21 and E22 represent the ranges in which the flow rate of the non-condensable gas NCG is increased by operating compressor 56b.

[0069] (1) When the noncondensable gas emission rate Qs is less than the emission rate Q21 The control device 158 stops the compressor 56b and discharges noncondensable gas NCG from the ejector 54a. More specifically, the control device 158 controls the compressor 56b to stop, open valves 83a and 84a, and close valves 83b, 83c, 84b, and 84c.

[0070] (2) When the noncondensable gas emission rate Qs is Q21 or higher and less than Q22 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejector 54a. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83a and 84a, and closes valves 83b, 83c, 84b, and 84c.

[0071] (3) When the noncondensable gas emission rate Qs is Q22 or higher and less than Q23 The control device 158 stops the compressor 56b and discharges noncondensable gas NCG from the ejectors 54a and 54b. More specifically, the control device 158 controls the compressor 56b to stop, open valves 83a, 83b, 84a, and 84b, and close valves 83c and 84c.

[0072] (4) When the noncondensable gas emission rate Qs is Q23 or higher and less than Q24 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejectors 54a and 54b. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83a, 83b, 84a and 84b, and closes valves 83c and 84c.

[0073] (5) When the noncondensable gas emission rate Qs is equal to or greater than the emission rate Q24 The control device 158 stops the compressor 56b and discharges non-condensable gas (NCG) from the ejectors 54a, 54b, and 54c. More specifically, the control device 158 controls the compressor 56b to stop and open valves 83a, 83b, 83c, 84a, 84b, and 84c.

[0074] Furthermore, the non-condensable gas reduction system 150 may be configured to use the compressor 56b to process non-condensable gas NCG exceeding the capacity of the ejectors 54a, ejectors 54b, and ejectors 54c when NCG is discharged in excess of the ejectors' capacity. In other words, the compressor 56b may be activated when the non-condensable gas discharge rate Qs exceeds 100%.

[0075] For example, we will describe an example where ejectors 54a, 54b, and 54c are switched when each of them reaches its maximum capacity. Figure 9 is a diagram illustrating the processing of the non-condensable gas reduction system of the first reference example.

[0076] For example, when the ejectors 54a, 54b, and 54c are switched when they reach their respective maximum capacities, the operating ranges of ejectors 54a, 54b, and 54c become range A2z, range B2z, and range C2z, respectively, as shown in Figure 9. Comparing Figure 8 and Figure 9, the non-condensable gas reduction system 150 can reduce the exhaust of excess non-condensable gas (NCG) by the amount of range RD2 shown by the dot pattern. For example, in the first reference example non-condensable gas reduction system shown in Figure 9, the excess emissions were 33%, but with the non-condensable gas reduction system 150 shown in Figure 8, the excess emissions can be reduced to 16%.

[0077] Next, we will explain the case where ejectors 54a, 54b, and 54c have different processing capacities. Here, we will explain an example where ejectors 54a, 54b, and 54c each have different processing capacities, but it is sufficient that at least one of ejectors 54a, 54b, and 54c has a different capacity from the other ejectors. For example, we will explain the case where the processing capacities of ejectors 54a, 54b, and 54c are 2:3:4. For example, ejectors 54a, 54b, and 54c discharge non-condensable gas NCG at flow rates corresponding to discharge rates Q31, Q32, and Q33, respectively, when the compression section 56 is not pressurized. When the compression section 56 is not pressurized, the non-condensable gas NCG is discharged by the three ejectors 54a, 54b, and 54c, and this is defined as 100% of the non-condensable gas discharge rate Qs.

[0078] Figure 10 is a diagram illustrating the processing of a non-condensable gas reduction system, which is an example of a non-condensable gas reduction system according to the second embodiment. In Figure 10, ejectors 54a, 54b, and 54c are assumed to have different processing capacities.

[0079] In Figure 10, the horizontal axis represents the non-condensable gas emission rate Qs calculated in step S3, and the vertical axis represents the actual treatment amount Qe, which corresponds to the actual flow rate of non-condensable gas NCG discharged. In Figure 10, both the horizontal and vertical axes are shown with the design maximum discharge flow rate of non-condensable gas NCG of the non-condensable gas reduction system 150 set to 100%.

[0080] In Figure 10, range A3 represents the range in which non-condensable gas NCG is discharged by ejector 54a, range B3 represents the range in which non-condensable gas NCG is discharged by ejector 54b, and range C3 represents the range in which non-condensable gas NCG is discharged by ejector 54c. Also in Figure 10, ranges E31 to E36 each represent the range in which the flow rate of non-condensable gas NCG is increased by operating compressor 56b.

[0081] (1) When the noncondensable gas emission rate Qs is less than emission rate Q31 The control device 158 stops the compressor 56b and discharges noncondensable gas NCG from the ejector 54a. More specifically, the control device 158 controls the compressor 56b to stop, open valves 83a and 84a, and close valves 83b, 83c, 84b, and 84c.

[0082] (2) When the noncondensable gas emission rate Qs is Q31 or higher, and less than Q32 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejector 54a. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83a and 84a, and closes valves 83b, 83c, 84b, and 84c.

[0083] (3) When the noncondensable gas emission rate Qs is Q32 or higher and less than Q33 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejector 54b. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b, and controls it to open valves 83b and 84b and close valves 83a, 83c, 84a, and 84c.

[0084] (4) When the noncondensable gas emission rate Qs is Q33 or higher and less than Q34 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejector 54c. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83c and 84c, and closes valves 83a, 83b, 84a, and 84b.

[0085] (5) When the noncondensable gas emission rate Qs is Q34 or higher and less than Q35 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejectors 54a and 54b. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83a, 83b, 84a and 84b, and closes valves 83c and 84c.

[0086] (6) When the noncondensable gas emission rate Qs is Q35 or higher and less than Q36 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejectors 54a and 54c. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83a, 83c, 84a and 84c, and close valves 83b and 84b.

[0087] (7) When the noncondensable gas emission rate Qs is Q36 or higher and less than Q37 The control device 158 operates the compressor 56b to discharge non-condensable gas NCG from the ejectors 54b and 54c. More specifically, the control device 158 sets the rotational speed of the compressor 56b based on the non-condensable gas discharge rate Qs, operates the compressor 56b to open valves 83b, 83c, 84b, and 84c, and closes valves 83a and 84a.

[0088] (8) When the noncondensable gas emission rate Qs is equal to or greater than the emission rate Q37 The control device 158 stops the compressor 56b and discharges noncondensable gas NCG from the ejectors 54a, 54b, and 54c. More specifically, the control device 158 stops the compressor 56b and opens valves 83a, 83b, 83c, 84a, 84b, and 84c.

[0089] Furthermore, the non-condensable gas reduction system 150 may be configured to use the compressor 56b to process non-condensable gas NCG exceeding the capacity of the ejectors 54a, ejectors 54b, and ejectors 54c when NCG is discharged in excess of the ejectors' capacity. In other words, the compressor 56b may be activated when the non-condensable gas discharge rate Qs exceeds 100%.

[0090] For example, we will describe an example in which non-condensable gas NCG is exhausted using only ejectors 54a, 54b, and 54c. Figure 11 is a diagram illustrating the processing of the non-condensable gas reduction system in the second reference example.

[0091] For example, when exhausting non-condensable gas NCG using only ejectors 54a, 54b, and 54c, the operating ranges of ejectors 54a, 54b, and 54c are range A3z, range B3z, and range C3z, respectively, as shown in Figure 11. Comparing Figure 10 and Figure 11, the non-condensable gas reduction system 150 reduces the pump power required to pump the excess coolant CWa relative to the processing volume of surplus non-condensable gas NCG by the amount of range RD3 indicated by the dot pattern. For example, in the second reference example non-condensable gas reduction system shown in Figure 11, the excess pump power was 16%, but with the non-condensable gas reduction system 150 shown in Figure 10, the excess pump power can be reduced to 6%.

[0092] Next, a modified example of the compression section will be described. Figure 12 is a schematic diagram of the configuration of a compression section 156, which is a modified example of the compression section in the noncondensable gas reduction system according to the embodiment of this disclosure. The compression section 156 is provided in place of the compression section 56.

[0093] The compression section 156 controls the flow rate by so-called spillback control.

[0094] The compression unit 156 pressurizes the non-condensable gas NCG supplied from the condenser 30 to the ejector 54. The compression unit 156 pressurizes the non-condensable gas NCG discharged from the condenser 30 and supplies it to the ejector 54.

[0095] The compression section 156 has a main flow path 156m, a bypass flow path 156n, and a recycle flow path 156p. The compression section 156 is equipped with a check valve 156a in the main flow path 156m. The check valve 156a allows the non-condensable gas NCG to flow in one direction, specifically from the condenser 30 to the ejector 54. The compression section 156 is also equipped with a compressor 56b in the bypass flow path 156n. The compressor 156b is, for example, a positive displacement or turbo compressor.

[0096] The compression section 156 is equipped with a spillback valve 156c in the recycling passage 156p. The recycling passage 156p is provided to recycle non-condensable gas (NCG) from the discharge side to the suction side of the compressor 156b. The flow rate of non-condensable gas (NCG) discharged from the compression section 156 is controlled by adjusting the opening of the spillback valve 156c.

[0097] According to the non-condensable gas reduction system of the second embodiment, non-condensable gas can be efficiently processed when the amount of non-condensable gas discharged from a geothermal power plant fluctuates.

[0098] For example, the amount of non-condensable gases emitted from geothermal power plants fluctuates due to factors such as changes in planned power generation and the decline in steam production during long-term operation. Therefore, it is necessary to address these fluctuations in non-condensable gas emissions from geothermal power plants.

[0099] For example, when reducing non-condensable gases using ejectors, the number of ejectors is controlled accordingly. However, if non-condensable gases are reduced using only ejectors, there may be excess capacity, leading to decreased efficiency. Also, if non-condensable gases are reduced using only ejectors, and an excessive amount of non-condensable gas is attempted to be processed compared to the design, the ejector's operating point may not match, resulting in malfunction.

[0100] Another option is to process the entire amount of non-condensable gas using a compressor. However, processing the entire amount of non-condensable gas with a compressor may increase initial and running costs.

[0101] Therefore, according to the non-condensable gas reduction system of this disclosure, by combining a main ejector and a backup compressor, non-condensable gas can be efficiently processed when the amount of non-condensable gas discharged from a geothermal power plant fluctuates.

[0102] <Variation> In the example described above, a condenser 30, which is a surface contact type condenser, was used, but a direct contact type condenser may also be used as the condenser. A modified example using a direct contact type condenser in the non-condensable gas reduction system according to the second embodiment will be described.

[0103] Next, Figure 13 is a schematic diagram of the configuration of a geothermal power plant 3, which is a modified example of a geothermal power plant equipped with a non-condensable gas reduction system 150, which is an example of a non-condensable gas reduction system according to the second embodiment.

[0104] The geothermal power plant 3 comprises a gas-liquid separator 10, a power generation unit 20, a condenser 230, a cooling unit 240, a non-condensable gas reduction system 150, and a control unit 260. The geothermal power plant 3 also comprises valves 81 and 82, and pumps 91 and 232. The control unit 260 has the same functions as the control unit 60.

[0105] For geothermal power plant 3, the configurations common to geothermal power plant 1 or geothermal power plant 2 should be referred to in the description of geothermal power plant 1 or geothermal power plant 2, and detailed explanations will be omitted here.

[0106] [Condenser 230] The condenser 230 cools the steam ST discharged from the turbine 21 with coolant CWA, more specifically coolant CWA1, supplied from the cooling unit 240. The condenser 230 is a so-called direct-contact condenser. The condenser 230 is equipped with a nozzle section 231. The nozzle section 231 is equipped with multiple nozzles that spray the coolant CWA1 as a mist. The nozzle section 231 may be equipped with just one nozzle. The condenser 230 performs heat exchange with the steam ST by spraying the coolant CWA1 onto the steam ST and bringing it into direct contact. The steam ST is cooled by the heat exchange between the coolant CWA1 and the steam ST. The steam ST condenses into water as it is cooled in the condenser 230. In the condenser 230, which is a direct-contact condenser, the coolant CWA1 is in direct contact with the steam ST. The coolant CWA2 contains the water that has condensed from the steam ST.

[0107] [Cooling section 240] The cooling unit 240 supplies coolant CWA to cool the steam ST in the condenser 230. The cooling unit 240 is a cooling tower. Pump 232 sends the coolant CWA2, which has become hot after cooling the steam ST in the condenser 230, to the cooling unit 240. The cooling unit 240 cools the coolant CWA2. The coolant CWA cooled in the cooling unit 240 is sent to the condenser 230 by pump 91. In the condenser 230, the coolant CWA2, whose temperature has risen due to heat exchange with the steam ST, returns to the cooling unit 240 and is cooled.

[0108] The cooling unit 240 is a forced-air wet cooling tower. The cooling unit 240 is a so-called wet cooler. The cooling unit 240 brings the coolant CWA2 into direct contact with air. The cooling unit 240 cools the coolant CWA2 through the latent heat of vaporization and sensible heat transfer of the coolant CWA2 when it is in direct contact with air. The cooling unit 240 is a suction-type counterflow cooling tower.

[0109] The cooling unit 240 comprises a fan 241, a nozzle unit 242, and a packing material 243. The fan 241 discharges outside air drawn into the unit through the opening 240h. The nozzle unit 242 has multiple nozzles that spray the coolant CWA2 supplied from the condenser 230 as a mist onto the packing material 243. The nozzle unit 242 may have just one nozzle.

[0110] As air passes through the gaps in the filler material 243, the coolant CWA2 sprayed from the nozzle section 242 exchanges heat with the air.

[0111] The coolant CWA cooled in the cooling unit 240 is supplied to the condenser 230 by the pump 91.

[0112] In the example described above, the cooling section 240 is described as a suction-type counterflow cooling tower. However, the cooling section of the non-condensable gas reduction system according to this embodiment is not limited to a suction-type counterflow cooling tower. For example, the cooling section of the non-condensable gas reduction system according to this embodiment may be a forced-air counterflow cooling tower, a suction-type crossflow cooling tower, or a forced-air crossflow cooling tower. Furthermore, the cooling section of the non-condensable gas reduction system according to this embodiment may be a naturally ventilated cooling tower.

[0113] In the non-condensable gas reduction system 150, each of the ejectors 54a, 54b, and 54c is driven by coolant CWA, more specifically coolant CWAa, which is a part of coolant CWA1. Coolant CWAa is pumped by pump 55. Each of the ejectors 54a, 54b, and 54c discharges a mixed liquid MW, which is a mixture of non-condensable gas NCG and coolant CWAa.

[0114] In addition, in the geothermal power plant 1 equipped with a non-condensable gas reduction system 50, which is an example of a non-condensable gas reduction system according to the first embodiment, a direct-contact type condenser 230 may be used instead of the surface-contact type condenser 30.

[0115] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0116] 1, 2, 3 Geothermal power plants 10 Gas-liquid separator 20 Power Generation Department 30, 230 condenser 40, 240 Cooling section 50, 150 Non-condensable gas reduction system 54, 54a, 54b, 54c Ejectors 55 pumps 56, 156 Compression section 56b, 156b Compressors 58, 158 Control device 75 Flow meter 83, 83a, 83b, 83c, 84a, 84b, 84c valves 156c Spillback Valve GF geothermal fluid HW hot water MW mixture NCG (Non-condensable gas) PWL production well RWL Reinforcement Well ST Steam

Claims

1. In a geothermal power plant, a non-condensable gas reduction system returns the non-condensable gas that remains after cooling in the condenser in the first gas contained in the geothermal fluid that springs from the production well back to the reinjection well. A pump for pressurizing the first liquid sent to the injection well, An ejector driven by the first liquid, which attracts the non-condensable gas and discharges a second liquid which is a mixture of the first liquid and the non-condensable gas, A compressor that pressurizes the non-condensable gas supplied from the condenser to the ejector, Equipped with, Non-condensable gas reduction system.

2. The system includes a control device that controls the first flow rate of the non-condensable gas supplied from the condenser to the ejector, The control device controls the first flow rate based on the flow rate of the non-condensable gas contained in the first gas. The non-condensable gas reduction system according to claim 1.

3. The control device controls the rotational speed of the compressor. The non-condensable gas reduction system according to claim 2.

4. The control device controls the rotational speed so that the pressure in the condenser becomes a predetermined pressure. The non-condensable gas reduction system according to claim 3.

5. The control device controls the flow rate of the non-condensable gas recycled from the discharge side to the suction side of the compressor. The non-condensable gas reduction system according to claim 2.

6. The system comprises multiple ejectors, The control device further controls the number of ejectors to be operated. A non-condensable gas reduction system according to any one of claims 2 to 5.

7. At least one of the plurality of ejectors has a different capability from the other ejectors. The non-condensable gas reduction system according to claim 6.

8. The control device controls each of the plurality of ejectors to open and close a first valve provided in a first channel through which the supplied noncondensable gas flows, and a second valve provided in a second channel through which the supplied first liquid flows. The non-condensable gas reduction system according to claim 6.

Images