Non-condensable gas reduction system

Abstract

The present disclosure provides a non-condensable gas reduction system that is easy to maintain and returns non-condensable gas contained in geothermal fluid to a reduction well. [Solution] A non-condensable gas reduction system for use in a geothermal power plant comprising a gas-liquid separator that separates geothermal fluid flowing from a production well into a first gas and a first liquid, an evaporator that performs heat exchange between the first gas and a working medium, a turbine that rotates by the working medium discharged from the evaporator, and a condenser that cools the working medium that rotates the turbine and condenses the working medium into a liquid, the non-condensable gas reduction system comprising: a pump that pressurizes a third liquid to be sent to a reinjection well; and an ejector driven by the third liquid, that attracts non-condensable gas contained in the first gas and remaining uncondensed in the evaporator, and discharges a fourth liquid which is a mixture of the third liquid and the non-condensable gas, wherein the first liquid and the fourth liquid are mixed and sent to the reinjection well.

Description

[Technical field]

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

[0002] Patent Document 1 discloses a method for disposing of non-condensable gases generated in geothermal power generation facilities, in which the non-condensable gases generated in a condenser installed downstream of a steam turbine are injected into a reinjection well for hot water reinjection, thereby reducing the gas underground together with the reduced hot water.

[0003] Patent Document 2 discloses a geothermal power plant that includes a reduced water flow path that transports reduced water to a reduced well, a gas extraction device that extracts gas from a condenser, and a gas flow path that supplies the gas extracted from the condenser to the reduced water flow path and mixes it with the reduced water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-177507 [Patent Document 2] JP 2018-017188 A Summary of the Invention [Problem to be solved by the invention]

[0005] In geothermal power generation, if non-condensable gases such as carbon dioxide or hydrogen sulfide are present, the gas accumulates at the top of the evaporator, reducing the liquid contact area inside the evaporator and lowering the heat exchange efficiency. To prevent this from decreasing, the non-condensable gases are removed using an extraction route or extractor that utilizes their own pressure. For example, they are sent from the evaporator to a cooling tower, mixed with air, and released into the atmosphere.

[0006] The present disclosure provides a non-condensable gas reduction system that is easy to maintain and returns non-condensable gas contained in geothermal fluid to a reduction well. [Means for solving the problem]

[0007] The present disclosure provides a non-condensable gas reduction system for use in a geothermal power plant, comprising: a gas-liquid separator that separates geothermal fluid flowing from a production well into a first gas and a first liquid; an evaporator that performs heat exchange between the first gas and a working medium; a turbine that rotates by the working medium discharged from the evaporator; and a condenser that cools the working medium that rotates the turbine and condenses the working medium into a liquid, the non-condensable gas reduction system comprising: a pump that pressurizes a third liquid sent to a reinjection well; and an ejector that is driven by the third liquid, attracts non-condensable gas contained in the first gas and remains uncondensed in the evaporator, and discharges a fourth liquid in which the third liquid and the non-condensable gas are mixed, and the first liquid and the fourth liquid are mixed and sent to the reinjection well. Effect of the Invention

[0008] The present disclosure provides a non-condensable gas reduction system that is easy to maintain and returns non-condensable gas contained in geothermal fluid to a reduction well. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing an outline of the configuration of the ejector included in the non-condensable gas reduction system according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing an outline of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the second embodiment. [Figure 4] FIG. 4 is a diagram showing an outline of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the third embodiment. [Diagram 5] FIG. 5 is a diagram showing an outline of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the fourth embodiment. [Figure 6]FIG. 6 is a diagram illustrating the determination of dissolution of non-condensable gas in the non-condensable gas reduction system according to the embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram illustrating the dissolution determination of non-condensable gas in the non-condensable gas reduction system according to the embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram illustrating a first example of a process performed in a non-condensable gas reduction system according to an embodiment of the present disclosure when the non-condensable gas is not dissolved. [Figure 9] FIG. 9 is a diagram illustrating a second example of processing in a case where the non-condensable gas is not dissolved in the non-condensable gas reduction system according to the embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram illustrating a third example of a process when the non-condensable gas is not dissolved in the non-condensable gas reduction system according to the embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram showing an outline of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0011] In addition, in the description of the specification and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals to avoid redundant explanation. In addition, in order to facilitate understanding, the scale of each part in the drawings may differ from the actual scale.

[0012] First Embodiment The non-condensable gas reduction system according to the first embodiment will be described. The non-condensable gas reduction system according to the first embodiment is used in a geothermal power plant. The geothermal power plant in which the non-condensable gas reduction system according to the first embodiment is used includes a gas-liquid separator that separates a geothermal fluid emerging from a production well into a first gas and a first liquid, and an evaporator that performs heat exchange between the first gas and a working medium. The geothermal power plant in which the non-condensable gas reduction system according to the first embodiment is used also includes a turbine that is rotated by the working medium discharged from the evaporator, and a condenser that cools the working medium that rotated the turbine and condenses the working medium into a liquid. The non-condensable gas reduction system according to the first embodiment also includes a pump that pressurizes a third liquid sent to the reduction well, and an ejector. The ejector in the non-condensable gas reduction system according to the first embodiment is driven by the third liquid, attracts the non-condensable gas contained in the first gas and remaining uncondensed in the evaporator, and discharges a fourth liquid in which the third liquid and the non-condensable gas are mixed. Furthermore, in the non-condensable gas reduction system according to the first embodiment, the first liquid and the fourth liquid are mixed and sent to the reinjection well. Also, in the non-condensable gas reduction system according to the first embodiment, the third liquid is a condensed liquid obtained by condensing the first gas in the evaporator.

[0013] Next, 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 equipped with 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, an evaporator 35, a cooling unit 40, a non-condensable gas reduction system 50, and a control unit 60. The geothermal power plant 1 is a so-called binary type geothermal power generation type geothermal power plant. The geothermal power plant 1 also includes valves 81 and 82, and pumps 91 and 93.

[0015] [Gas-liquid separator 10] The gas-liquid separator 10 separates the geothermal fluid GF spouting from the production well PWL into steam ST and hot water HW. The geothermal fluid GF spouting from the production well PWL is allowed to flow or blocked by a valve 81. The steam ST discharged from the gas-liquid separator 10 is sent to an evaporator 35. The hot water HW discharged from the gas-liquid separator 10 is discharged to a 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 steam, but contains gases discharged from the production well PWL, such as carbon dioxide and hydrogen sulfide.

[0017] [Power Generation Section 20] The power generation unit 20 generates power using the working medium RF that has been heated by the steam ST and turned into a gas. The power generation unit 20 includes a turbine 21 and a generator 22. The turbine 21 is rotated by the working medium RF. More specifically, the turbine 21 is rotated by the pressure difference between the working medium RF that has been converted from a liquid to a gas through heat exchange with the steam ST in the evaporator 35, and the working medium RF that has been cooled by the coolant CW1 in the condenser 30 and turned from a gas to a liquid. The generator 22 is connected to the turbine 21. When the turbine 21 rotates, the rotating shaft of the generator 22 rotates to generate power. The power generated by the generator 22 is supplied to the outside.

[0018] The working medium RF is a medium having a boiling point lower than that of water, such as ammonia, pentane, or a fluorocarbon substitute. The working medium RF is condensed from a gas state to a liquid state by being cooled in the condenser 30. The working medium RF is evaporated from a liquid state to a gas state by being heated in the evaporator 35. The working medium RF is circulated by the pump 91 through the evaporator 35, the turbine 21, and the condenser 30 in this order.

[0019] [Condenser 30] The condenser 30 cools the working medium RF discharged from the turbine 21 with the cooling liquid CW1 supplied from the cooling unit 40. The working medium RF is condensed and changes from a gas state to a liquid state by being cooled in the condenser 30. The condenser 30 is, for example, a shell-and-tube heat exchanger, a plate-type heat exchanger, or the like.

[0020] [Evaporator 35] The evaporator 35 heats the working medium RF with the steam ST supplied from the gas-liquid separator 10. When the evaporator 35 heats the working medium RF, the working medium RF evaporates and changes from a liquid to a gas. The evaporator 35 is, for example, a multi-tube heat exchanger. In the evaporator 35, heat is exchanged between the steam ST and the working medium RF, so that the steam ST is cooled. When the steam ST is cooled, the steam ST condenses to become a condensed liquid HWa.

[0021] Non-condensable gas NCG such as carbon dioxide and hydrogen sulfide contained in the steam ST accumulates in the upper part of the evaporator 35. When the non-condensable gas NCG accumulates, the liquid level of the condensed liquid HWa formed by condensing the steam ST in the evaporator 35 drops. When the liquid level of the condensed liquid HWa formed by condensing the steam ST in the evaporator 35 drops, the heat exchange efficiency between the steam ST and the working medium RF in the evaporator 35 decreases. Therefore, it is desirable to discharge the non-condensable gas NCG accumulated in the evaporator 35 from the evaporator 35.

[0022] In the geothermal power plant 1, the non-condensable gas NCG accumulated in the evaporator 35 is attracted by the non-condensable gas reduction system 50 and discharged to the reduction well RWL.

[0023] The evaporator 35 is provided with a level gauge 84. The level gauge 84 measures the liquid level of the condensed liquid HWa condensed in the evaporator 35. For example, when non-condensable gas NCG accumulates in the evaporator 35, the liquid level measured by the level gauge 84 drops.

[0024] [Cooling section 40] The cooling unit 40 supplies a cooling liquid CW to cool the working medium RF in the condenser 30. The cooling unit 40 is, for example, a cooling tower. The cooling liquid CW1 cooled in the cooling unit 40 is sent to the condenser 30 by a pump 93. The cooling liquid CW2 whose temperature has increased by heat exchange with the steam ST in the condenser 30 is returned to the cooling unit 40 and cooled.

[0025] [Non-condensable gas reduction system 50] The non-condensable gas reduction system 50 induces and discharges the non-condensable gas NCG from the evaporator 35. The non-condensable gas reduction system 50 includes an ejector 54, a control device 58, pressure gauges 71, 72, and 73, a valve 83, and a pump 92. The ejector 54 is driven by the condensed liquid HWa condensed in the evaporator 35. The condensed liquid HWa is pumped by the pump 92. The ejector 54 discharges a mixed liquid MW obtained by mixing the non-condensable gas NCG and the condensed liquid HWa.

[0026] The mixed liquid MW discharged from the ejector 54 is mixed with the hot water HW and sent to the reinjection well RWL. The mixed liquid MW and the hot water HW sent to the reinjection well RWL are allowed to flow or blocked by a valve 82.

[0027] The following describes the structure of the ejector 54. Fig. 2 is a diagram showing an outline of the configuration of the ejector 54 included in the non-condensable gas reduction system 50, which is an example of the non-condensable gas reduction system according to the first embodiment.

[0028] The ejector 54 includes 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 sucked in from the induction port 51a. The drive nozzle 52 is inserted into the induction section 51. The drive port 52a of the drive nozzle 52 is supplied with condensate HWa pressurized by the pump 92. The high-speed condensate HWa is discharged from the tip of the drive nozzle 52, and the non-condensable gas NCG present in the induction section 51 is discharged while being mixed with the condensate HWa. The ejector 54 sucks in the non-condensable gas NCG by discharging the non-condensable gas NCG.

[0029] The ejector 54 mixes the non-condensable gas NCG with the condensed liquid HWa, and discharges the mixed liquid MW through the expanded tube portion 53.

[0030] The non-condensable gas NCG and the condensed liquid HWa are mixed in the ejector 54 and discharged into the ejector 54. The mixed liquid MW is then mixed with hot water HW and sent to the reinjection well RWL.

[0031] The ejector 54 is provided on the ground. By providing the ejector 54 on the ground, maintenance of the ejector 54 can be facilitated.

[0032] The control device 58 is mainly configured with a computer including, for example, a processor, a storage device such as a memory, an auxiliary storage device, and an input / output interface device with the outside. The processor is, for example, a central processing unit (CPU), a graphics processing unit (GPU), or a micro processing unit (MPU). The control device 58 may be, for example, a programmable logic controller (PLC).

[0033] When the liquid level measured by the level gauge 84 drops, the control device 58 determines that the non-condensable gas NCG has accumulated in the evaporator 35, and opens the valve 83 and operates the pump 92 to discharge the non-condensable gas NCG from the ejector 54.

[0034] Specifically, the level gauge 84 measures the liquid level of the condensed liquid HWa formed by condensation of the steam ST in the evaporator 35. The control device 58 controls the opening and closing of the valve 83 according to the level measured by the level gauge 84. More specifically, when the liquid level of the condensed liquid HWa in the evaporator 35 measured by the level gauge 84 becomes lower than a predetermined liquid level, the control device 58 opens the valve 83 and starts the pump 92. By opening the valve 83 and starting the pump 92, the non-condensable gas NCG is discharged from the evaporator 35 by the ejector 54. Furthermore, when the liquid level of the condensed liquid HWa in the evaporator 35 measured by the level gauge 84 becomes higher than the predetermined liquid level, the control device 58 closes the valve 83 and stops the pump 92. By closing the valve 83 and stopping the pump 92, the discharge of the non-condensable gas NCG from the evaporator 35 is stopped.

[0035] When the pressure P1 on the pressure gauge 71 becomes higher than the pressure P2 on the pressure gauge 73 during power generation, the control device 58 controls the valve 83 to close in order to prevent the hot water HW from flowing to the evaporator 35. The valve 83 is provided in a flow path through which the non-condensable gas NCG flows between the evaporator 35 and the ejector 54. The pressure P1 on the pressure gauge 71 is the pressure of the hot water HW, and the pressure P2 on the pressure gauge 73 is the discharge pressure of the pump 92.

[0036] The controller 58 may also use a pressure gauge 72 to monitor the pressure of the non-condensable gas NCG.

[0037] [Control unit 60] The control unit 60 controls the entire geothermal power plant 1. The control unit 60 is mainly configured with a computer including, for example, a processor, a storage device such as a memory, an auxiliary storage device, and an input / output interface device with the outside. The processor is, for example, a CPU, a GPU, or an MPU. The control unit 60 may be, for example, a programmable logic controller.

[0038] The control unit 60 controls each of the pump 91 and the pump 93. When generating power, the control unit 60 controls each of the pumps 91 and 93 to start them. When stopping power generation, the control unit 60 controls each of the pumps 91 and 93 to stop them.

[0039] Geothermal power generation mainly emits carbon dioxide as a non-condensable gas, although the amount is much less than that of thermal power generation. For example, 90% of the non-condensable gas contained in the geothermal fluid discharged from production wells is carbon dioxide. Overseas, for example, New Zealand already imposes a carbon tax on carbon dioxide emitted from geothermal power generation. Similarly, in Japan, the cost of geothermal power generation may increase due to the carbon dioxide contained in non-condensable gas.

[0040] According to the non-condensable gas reduction system of the first embodiment, by returning non-condensable gas to the reinjection well, it is possible to reduce non-condensable gas such as carbon dioxide emitted into the atmosphere from geothermal power generation.

[0041] Furthermore, according to the non-condensable gas reduction system of the first embodiment, by using an ejector that is driven by the condensate formed by condensing the first gas in the evaporator and attracts the non-condensable gas, it is possible to reduce the impact on the natural environment, such as the toxicity of hydrogen sulfide contained in the non-condensable gas to the human body and the contamination of surrounding plants and soil.

[0042] The pressure gauge 71 is an example of a first pressure gauge, the pressure gauge 73 is an example of a second pressure gauge, and the level gauge 84 is an example of a second level gauge.

[0043] Second Embodiment A non-condensable gas reduction system according to the second embodiment will be described. In the non-condensable gas reduction system according to the second embodiment, the third liquid is a part of the cooling liquid sent to the condenser, instead of the third liquid being a condensed liquid obtained by condensing the first gas in the evaporator in the non-condensable gas reduction system according to the first embodiment.

[0044] Next, the non-condensable gas reduction system according to the second embodiment will be described in detail with reference to the drawings. Fig. 3 is a diagram showing an outline of the configuration of a geothermal power plant 2 equipped with a non-condensable gas reduction system 150, which is an example of the non-condensable gas reduction system according to the second embodiment.

[0045] The geothermal power plant 2 includes a gas-liquid separator 10, a power generation unit 20, a condenser 30, an evaporator 35, a cooling unit 40, a non-condensable gas reduction system 150, and a control unit 160. The geothermal power plant 2 also includes valves 81 and 82, and pumps 91 and 93. The control unit 160 has the same functions as the control unit 60.

[0046] Regarding the configuration of geothermal power plant 2 that is common to geothermal power plant 1, the description of geothermal power plant 1 should be referred to, and detailed description thereof will be omitted here.

[0047] The non-condensable gas reduction system 150 pressurizes the coolant CWa, which is a part of the coolant CW, using a pump 92, and supplies the pressurized coolant CWa to an ejector 154. The non-condensable gas reduction system 150 includes an ejector 154, a control device 158, pressure gauges 71, 72, and 73, a valve 83, and a pump 92. The ejector 154 has the same configuration as the ejector 54. The control device 158 has the same function and configuration as the control device 58.

[0048] The ejector 154 is driven by a cooling liquid CWa that is a part of the cooling liquid CW. The cooling liquid CWa is pumped by the pump 92. The ejector 154 ejects a mixed liquid MW that is a mixture of the non-condensable gas NCG and the cooling liquid CWa.

[0049] The ejector 154 mixes the non-condensable gas NCG and the cooling liquid CWa and discharges the mixed liquid MW. The mixed liquid MW, which is the mixture of the non-condensable gas NCG and the cooling liquid CWa and discharged in the ejector 154, is mixed with the hot water HW and the condensate HWa and sent to the reinjection well RWL.

[0050] According to the non-condensable gas reduction system of the second embodiment, as in the non-condensable gas reduction system of the first embodiment, non-condensable gases such as carbon dioxide emitted into the atmosphere from geothermal power generation can be reduced by returning the non-condensable gas to the reduction well.

[0051] Third Embodiment A non-condensable gas reduction system according to the third embodiment will be described. In the non-condensable gas reduction system according to the third embodiment, the third liquid is a part of the first liquid, instead of the third liquid being a condensate obtained by condensing the first gas in the evaporator in the non-condensable gas reduction system according to the first embodiment.

[0052] Next, the non-condensable gas reduction system according to the third embodiment will be described in detail with reference to the drawings. Fig. 4 is a diagram showing an outline of the configuration of a geothermal power plant 3 equipped with a non-condensable gas reduction system 250, which is an example of the non-condensable gas reduction system according to the third embodiment.

[0053] The geothermal power plant 3 includes a gas-liquid separator 10, a power generation unit 20, a condenser 30, an evaporator 35, a cooling unit 40, a non-condensable gas reduction system 250, and a control unit 260. The geothermal power plant 3 also includes valves 81 and 82, and pumps 91 and 93. The control unit 260 has the same functions as the control unit 60.

[0054] Regarding the configuration of geothermal power plant 3 that is common to geothermal power plant 1, the description of geothermal power plant 1 should be referred to, and detailed description thereof will be omitted here.

[0055] The non-condensable gas reduction system 250 pressurizes hot water HWb, which is a part of the hot water HW discharged from the gas-liquid separator 10, using a pump 92, and supplies the pressurized water to an ejector 254. The non-condensable gas reduction system 250 includes an ejector 254, a control device 258, pressure gauges 71, 72, and 73, a valve 83, and a pump 92. The ejector 254 has the same configuration as the ejector 54. The control device 258 has the same function and configuration as the control device 58.

[0056] The ejector 254 is driven by hot water HWb, which is a part of the hot water HW discharged from the gas-liquid separator 10. The hot water HWb is pumped by the pump 92. The ejector 254 discharges a mixed liquid MW obtained by mixing the non-condensable gas NCG and the hot water HWb.

[0057] The ejector 254 mixes the non-condensable gas NCG and the hot water HWb and discharges the mixed liquid MW. The mixed liquid MW, which is the mixture of the non-condensable gas NCG and the hot water HWb and discharged in the ejector 254, is mixed with the hot water HW and the condensed liquid HWa and sent to the reinjection well RWL.

[0058] According to the non-condensable gas reduction system of the third embodiment, as in the non-condensable gas reduction system of the first embodiment, non-condensable gases such as carbon dioxide emitted into the atmosphere from geothermal power generation can be reduced by returning the non-condensable gas to the reduction well.

[0059] Fourth Embodiment A non-condensable gas reduction system according to the fourth embodiment will be described. A geothermal power plant equipped with the non-condensable gas reduction system according to the fourth embodiment further includes a reduction pit for storing the first liquid. In the non-condensable gas reduction system according to the fourth embodiment, the third liquid is a part of the first liquid stored in the reduction pit, instead of the third liquid being a condensate formed by condensing the first gas in the evaporator in the non-condensable gas reduction system according to the first embodiment.

[0060] Next, the non-condensable gas reduction system according to the fourth embodiment will be described in detail with reference to the drawings. Fig. 5 is a diagram showing an outline of the configuration of a geothermal power plant 4 equipped with a non-condensable gas reduction system 350, which is an example of the non-condensable gas reduction system according to the fourth embodiment.

[0061] The geothermal power plant 4 includes a gas-liquid separator 10, a power generation unit 20, a condenser 30, an evaporator 35, a cooling unit 40, a non-condensable gas reduction system 350, and a control unit 360. The geothermal power plant 4 also includes valves 81 and 82, and pumps 91 and 93. The geothermal power plant 4 further includes a reduction pit 311 and a pump 393. The control unit 360 has the same functions as the control unit 60.

[0062] Regarding the configuration of geothermal power plant 4 that is common to geothermal power plant 1, the description of geothermal power plant 1 should be referred to, and detailed description thereof will be omitted here.

[0063] The geothermal power plant 4 includes a reduction pit 311 that stores the hot water HW discharged from the gas-liquid separator 10. The hot water HW stored in the reduction pit 311 is sent to the reduction well RWL by a pump 393. In addition, hot water HWc, which is a part of the hot water HW stored in the reduction pit 311, is pressurized by a pump 92 and supplied to the ejector 354. The reduction pit 311 may be a tank or a pool.

[0064] The ejector 354 mixes the non-condensable gas NCG and the hot water HWc and discharges the mixed liquid MW. The mixed liquid MW, which is the mixture of the non-condensable gas NCG and the hot water HWc and discharged in the ejector 354, is mixed with the hot water HW and sent to the reinjection well RWL.

[0065] The non-condensable gas reduction system 350 pressurizes hot water HWc, which is a part of the hot water HW stored in the reduction pit 311, using a pump 92, and supplies the pressurized water to an ejector 354. The non-condensable gas reduction system 350 includes an ejector 354, a control device 358, a pressure gauge 371, a pressure gauge 72, a pressure gauge 73, a valve 83, and a pump 92. The non-condensable gas reduction system 350 measures the pressure P1 of the hot water HW using the pressure gauge 371 instead of the pressure gauge 71 in the non-condensable gas reduction system 50. The ejector 354 has the same configuration as the ejector 54. The control device 358 has the same function and configuration as the control device 58.

[0066] The ejector 354 is driven by hot water HWc which is a part of the hot water HW stored in the reduction pit 311. The hot water HWc is pumped by the pump 92. The ejector 354 discharges a mixed liquid MW which is a mixture of the non-condensable gas NCG and the hot water HWc.

[0067] The ejector 354 mixes the non-condensable gas NCG and the hot water HWc and discharges the mixed liquid MW. The mixed liquid MW, which is the mixture of the non-condensable gas NCG and the hot water HWc and discharged in the ejector 354, is mixed with the hot water HW and sent to the reinjection well RWL.

[0068] According to the non-condensable gas reduction system of the fourth embodiment, as in the non-condensable gas reduction system of the first embodiment, non-condensable gases such as carbon dioxide emitted into the atmosphere from geothermal power generation can be reduced by returning the non-condensable gas to the reduction well.

[0069] <Determination of dissolution of non-condensable gas in a non-condensable gas reduction system according to an embodiment of the present disclosure> In the non-condensable gas reduction system according to the embodiment of the present disclosure, a method for determining whether the non-condensable gas is dissolved in the mixed liquid discharged by the ejector will be described. In the mixed liquid discharged from the ejector, it is desirable that the non-condensable gas is completely dissolved in the third liquid. Therefore, a method for determining whether the non-condensable gas is dissolved in the third liquid will be described.

[0070] 6 and 7 are diagrams for explaining the dissolution determination of non-condensable gas in the non-condensable gas reduction system according to the embodiment of the present disclosure. In the following explanation, the ejector 54 is used. The same applies when any of the ejector 154, ejector 254, and ejector 354 is used instead of the ejector 54.

[0071] A tank 455 is provided downstream of the ejector 54. A level gauge 474 is installed in the tank 455. The level gauge 474 measures the level of the liquid stored in the tank 455. The measurement result is output to the control device 458. The control device 458 executes a dissolution determination of the non-condensable gas NCG.

[0072] As shown in FIG. 7(A), if the non-condensable gas NCG is completely dissolved in the mixed liquid MW, the inside of the tank 455 is filled with the mixed liquid MW. On the other hand, as shown in FIG. 7(B), if the non-condensable gas NCG is not completely dissolved in the mixed liquid MW, the non-condensable gas NCG accumulates at the top of the tank. Therefore, when the non-condensable gas NCG accumulates, the height measured by the level meter 474 decreases by a height ΔL. Therefore, by measuring the level of the mixed liquid MW in the tank 455 using the level meter 474, it is possible to determine whether the non-condensable gas NCG is dissolved in the mixed liquid MW.

[0073] Here, a process when the non-condensable gas NCG is not dissolved will be described. FIG. 8 is a diagram for explaining a first example of a process when the non-condensable gas is not dissolved in the non-condensable gas reduction system according to the embodiment of the present disclosure. When the control device 558 determines that the non-condensable gas NCG is not dissolved based on the level measurement result of the level meter 474, the control device 558 opens a valve 556 provided in the pipe connecting the tank 455 and the ejector 54. By opening the valve 556, the non-condensable gas NCG is sucked from the ejector 54.

[0074] Another example will be described. FIG. 9 is a diagram for describing a second example of the process when the non-condensable gas is not dissolved in the non-condensable gas reduction system according to the embodiment of the present disclosure. In the second example, an additional ejector 650 is further provided. And, a pump 657 that supplies a driving flow to the ejector 650 is provided. The non-condensable gas NCG accumulated in the tank 455 is discharged from the ejector 650 other than the ejector 54. When the control device 658 determines that the non-condensable gas NCG is not dissolved based on the level measurement result of the level meter 474, it opens the valve 656, starts the pump 657, and uses the ejector 650 to suck the non-condensable gas NCG in the tank 455. The ejector 650 discharges the mixed liquid MW mixed with the non-condensable gas NCG into the reduction well RWL.

[0075] Further, another example will be described. FIG. 10 is a diagram for explaining a third example of a process when the non-condensable gas is not dissolved in the non-condensable gas reduction system according to the embodiment of the present disclosure. In the third example, a tank 756 for storing a chemical is provided. The chemical is, for example, an alkaline agent. When the control device 758 determines that the non-condensable gas NCG is not dissolved based on the level measurement result of the level meter 474, the control device 758 opens a valve 759 between the tank 455 and the tank 756 to inject the chemical into the tank 455. The chemical is injected, for example, by spraying or pouring from the top of the tank 455.

[0076] The above-mentioned examples may be appropriately combined in each of the non-condensable gas reduction systems according to the first to fourth embodiments.

[0077] Further, the control device 458, the control device 558, the control device 658, and the control device 758 have the function of the control device in the noncondensable gas reduction system according to the first to fourth embodiments.

[0078] The level gauge 474 is an example of a first level gauge.

[0079] Fifth embodiment A non-condensable gas reduction system according to the fifth embodiment will be described below. The non-condensable gas reduction system according to the fifth embodiment includes a plurality of ejectors in the non-condensable gas reduction system according to the first embodiment.

[0080] Next, the non-condensable gas reduction system according to the fifth embodiment will be described in detail with reference to the drawings. Fig. 11 is a diagram showing an outline of the configuration of a geothermal power plant 5 equipped with a non-condensable gas reduction system 850, which is an example of the non-condensable gas reduction system according to the fifth embodiment.

[0081] The geothermal power plant 5 includes a gas-liquid separator 10, a power generation unit 20, a condenser 30, an evaporator 35, a cooling unit 40, a non-condensable gas reduction system 850, and a control unit 860. The geothermal power plant 5 also includes a pump 91 and a pump 93.

[0082] Regarding the configuration of geothermal power plant 5 that is common to geothermal power plant 1, the description of geothermal power plant 1 should be referred to, and detailed description thereof will be omitted here.

[0083] The non-condensable gas reduction system 850 includes a plurality of ejectors 54, a control device 858, pressure gauges 71, 72, and 73, a valve 83, and a pump 92. The non-condensable gas reduction system 850 includes a plurality of ejectors 54, and thus includes a plurality of parallel lines including the ejectors 54. The non-condensable gas reduction system 850 includes a plurality of parallel lines including the ejectors 54, and thus can perform maintenance on the ejectors 54 without stopping the entire non-condensable gas reduction system 850 by operating some of the lines.

[0084] According to the non-condensable gas reduction system of the fifth embodiment, as in the non-condensable gas reduction system of the first embodiment, it is possible to reduce non-condensable gases such as carbon dioxide emitted into the atmosphere from geothermal power generation by returning the non-condensable gas to the reinjection well. Furthermore, according to the non-condensable gas reduction system of the fifth embodiment, by providing a plurality of ejectors, it is possible to improve maintainability, for example by switching between them during operation.

[0085] In the example of Fig. 11, a geothermal power plant 5 having a similar configuration to the geothermal power plant 1 equipped with a noncondensable gas reduction system 50, which is an example of the noncondensable gas reduction system according to the first embodiment, has been used as an example for explanation, but the noncondensable gas reduction system is not limited to the first embodiment. A geothermal power plant equipped with a noncondensable gas reduction system according to any of the second to fourth embodiments may also be provided with a plurality of lines including ejectors. In addition, in the noncondensable gas reduction system according to the fifth embodiment, the above-mentioned process for the case where the noncondensable gas is not dissolved may be performed.

[0086] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0087] 1, 2, 3, 4, 5 Geothermal power plant 10 Gas-liquid separator 20 Power Generation Division 21 Turbine 22 Generator 30 Condenser 35 Evaporator 40 Cooling section 50, 150, 250, 350, 850 Non-condensable gas reduction system 51 Attraction Section 51a Attraction Port 52 Driving Nozzle 52a Drive port 53 Expanded section 54, 154, 254, 354, 650 Ejector 58, 158, 258, 358, 458, 558, 658, 758, 858 Control Unit 60, 160, 260, 360, 860 Control unit 71, 72, 73, 371 Pressure gauge 81, 82, 83, 556, 656, 759 Valves 91, 92, 93, 393, 657 Pump 311 Reduction Pit 455, 756 Tank 84, 474 Level meter CW, CW1, CW2, CWa Coolant GF geothermal fluid HWa Condensate HW, HWb, HWc Hot water MW mixture NCG Non-condensable gas PWL Production well RWL Reinjection well ST Steam

Claims

1. A non-condensable gas reduction system for use in a geothermal power plant, comprising: a gas-liquid separator that separates a geothermal fluid emerging from a production well into a first gas and a first liquid; an evaporator that performs heat exchange between the first gas and a working medium; a turbine that is rotated by the working medium discharged from the evaporator; and a condenser that cools the working medium that has rotated the turbine and condenses the working medium into a liquid, A pump for pressurizing the third liquid sent to the reinjection well; an ejector that is driven by the third liquid, attracts non-condensable gas that is contained in the first gas and remains uncondensed in the evaporator, and ejects a fourth liquid that is a mixture of the third liquid and the non-condensable gas; Equipped with The first liquid and the fourth liquid are mixed and sent to the injection well. Non-condensable gas reduction system.

2. The third liquid is a condensed liquid obtained by condensing the first gas in the evaporator. The noncondensable gas reduction system of claim 1 .

3. The third liquid is a portion of the cooling liquid sent to the condenser. The noncondensable gas reduction system of claim 1 .

4. The third liquid is a part of the first liquid. The noncondensable gas reduction system of claim 1 .

5. The geothermal power plant further comprises a reduction pit for storing the first liquid; The third liquid is a portion of the first liquid stored in the reduction pit. The noncondensable gas reduction system of claim 1 .

6. The ejector is installed on the ground. The non-condensable gas reduction system according to any one of claims 1 to 5.

7. a tank connected downstream of the ejector; a first level meter for measuring the level of a liquid stored in the tank; A control device, The control device performs a determination of dissolution of the non-condensable gas in the fourth liquid according to the level measured by the first level meter. The non-condensable gas reduction system according to any one of claims 1 to 5.

8. When the control device determines that the non-condensable gas is not dissolved in the fourth liquid, the control device controls the ejector to discharge the non-condensable gas accumulated in the tank. The noncondensable gas reduction system of claim 7.

9. When the control device determines that the non-condensable gas is not dissolved in the fourth liquid, the control device controls the non-condensable gas accumulated in the tank to be discharged from another ejector different from the ejector to the reinjection well. The noncondensable gas reduction system of claim 7.

10. When the control device determines that the non-condensable gas is not dissolved in the fourth liquid, the control device controls to inject a chemical into the tank. The noncondensable gas reduction system of claim 7.

11. a first pressure gauge that measures a pressure of the first liquid; a second pressure gauge that measures the pressure of the third liquid; a valve provided in a flow path between the evaporator and the ejector; A control device, The control device closes the valve when a pressure of the first liquid measured by the first pressure gauge is higher than a pressure of the third liquid measured by the second pressure gauge. The non-condensable gas reduction system according to any one of claims 1 to 5.

12. a second level meter that measures a liquid level of a condensate formed by condensing the first gas in the evaporator; a valve provided in a flow path between the evaporator and the ejector; A control device, The control device controls opening and closing of the valve according to the level measured by the second level gauge. The non-condensable gas reduction system according to any one of claims 1 to 5.

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