Non-condensable gas reinjection system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-08-06
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025028017_13082026_PF_FP_ABST
Abstract
Description
Non-condensable gas reduction system
[0001] The present disclosure relates to a non-condensable gas reduction system.
[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 on the downstream side of a steam turbine is injected into a reduction well for hot water reduction, and is reduced underground together with the reduction 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.
[0004] Japanese Patent Laid-Open No. 9-177507 Japanese Patent Laid-Open No. 2018-017188
[0005] In geothermal power generation, when non-condensable gas such as carbon dioxide or hydrogen sulfide is contained, gas accumulates in the upper part of the evaporator, the liquid contact area in the evaporator decreases, and the heat exchange efficiency decreases. In order to prevent the decrease in heat exchange efficiency, the non-condensable gas is removed by an extraction path or an extractor using its own pressure. For example, it is sent from the evaporator to the cooling tower, mixed with air, and released into the atmosphere.
[0006] The present disclosure provides a non-condensable gas reduction system that returns non-condensable gas contained in a geothermal fluid with high maintainability to a reduction well.
[0007] This disclosure provides a non-condensable gas reduction system for use in a geothermal power plant, comprising: a gas-liquid separator for separating geothermal fluid flowing from a production well into a first gas and a first liquid; an evaporator for heat exchange between the first gas and a working medium; a turbine rotated by the working medium discharged from the evaporator; and a condenser for cooling the working medium that has rotated the turbine and for condensing the working medium into a liquid, wherein the system further comprises: a pump for pressurizing a third liquid sent to a reduction well; and an ejector driven by the third liquid for inducing non-condensable gas contained in the first gas that remains uncondensed in the evaporator, and for discharging a fourth liquid in which the third liquid and the non-condensable gas are mixed, thereby providing a non-condensable gas reduction system in which the first liquid and the fourth liquid are mixed and sent to the reduction well.
[0008] This disclosure provides a non-condensable gas reduction system that returns non-condensable gases contained in geothermal fluids to a reinjection well, which is highly maintainable.
[0009] 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 is a schematic diagram of the configuration of an ejector equipped with a non-condensable gas reduction system according to the first embodiment. Figure 3 is a schematic diagram of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the second embodiment. Figure 4 is a schematic diagram of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the third embodiment. Figure 5 is a schematic diagram of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the fourth embodiment. Figure 6 is a diagram illustrating the determination of dissolution of non-condensable gas in a non-condensable gas reduction system according to an embodiment of this disclosure. Figure 7 is a diagram illustrating the determination of dissolution of non-condensable gas in a non-condensable gas reduction system according to an embodiment of this disclosure. Figure 8 is a diagram illustrating a first example of processing when non-condensable gas is not dissolved in a non-condensable gas reduction system according to an embodiment of this disclosure. Figure 9 is a diagram illustrating a second example of processing when non-condensable gas is not dissolved in a non-condensable gas reduction system according to an embodiment of this disclosure. Figure 10 is a diagram illustrating a third example of processing when non-condensable gas is not dissolved in a non-condensable gas reduction system according to an embodiment of this disclosure. Figure 11 is a schematic diagram showing the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the fifth embodiment.
[0010] Embodiments will be described below with reference to the accompanying drawings. However, this disclosure is not limited to these examples, and is intended to include all modifications within the meaning and scope of 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] ≪First Embodiment≫ The non-condensable gas reduction system according to the first embodiment will now be described. The non-condensable gas reduction system according to the first embodiment is used in a geothermal power plant. The geothermal power plant using the non-condensable gas reduction system according to the first embodiment includes a gas-liquid separator that separates the geothermal fluid gushing from the 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 using the non-condensable gas reduction system according to the first embodiment also includes 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. Furthermore, the non-condensable gas reduction system according to the first embodiment includes a pump that pressurizes the 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, induces non-condensable gas contained in the first gas that remains uncondensed in the evaporator, and discharges a fourth liquid which is a mixture of the third liquid and the non-condensable gas. 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 reduction well. Also, in the non-condensable gas reduction system according to the first embodiment, the third liquid is the condensate obtained by condensing the first gas in the evaporator.
[0013] Next, with reference to the drawings, the non-condensable gas reduction system according to the first embodiment will be described in detail. Figure 1 is a schematic diagram of the configuration of a 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.
[0014] The geothermal power plant 1 comprises 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 geothermal power generation system. The geothermal power plant 1 also comprises valves 81 and 82, and pumps 91 and 93.
[0015] [Gas-Liquid Separator 10] The gas-liquid separator 10 separates the 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 allowed to flow or is blocked by the valve 81. The steam ST discharged from the gas-liquid separator 10 is sent to the evaporator 35. The hot water HW discharged from the gas-liquid separator 10 is discharged into the reinjection well RWL. The pressure gauge 71, described later, measures the pressure of the hot water HW.
[0016] Here, steam ST is not pure water vapor, but includes gases emitted from the production well PWL, such as carbon dioxide and hydrogen sulfide.
[0017] [Power Generation Unit 20] The power generation unit 20 generates electricity using a working medium RF that has been heated by steam ST and turned into a gas. The power generation unit 20 comprises a turbine 21 and a generator 22. The turbine 21 is rotated by the working medium RF. More specifically, the turbine 21 rotates due to the pressure difference between the working medium RF, which has been heated from liquid to gas in the evaporator 35 by heat exchange with steam ST, and the working medium RF, which has been cooled from gas to liquid in the condenser 30 by the coolant CW1. 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] The working medium RF is a medium with a lower boiling point than water, such as ammonia, pentane, or a fluorocarbon alternative. The working medium RF condenses from a gas to a liquid when cooled in the condenser 30. The working medium RF also evaporates from a liquid to a gas when heated in the evaporator 35. The working medium RF is circulated by the pump 91 in the order of evaporator 35, turbine 21, and condenser 30.
[0019] [Condenser 30] The condenser 30 cools the working medium RF discharged from the turbine 21 with coolant CW1 supplied from the cooling unit 40. The working medium RF condenses in the condenser 30, changing from a gas to a liquid. The condenser 30 is, for example, a multi-tube heat exchanger, a plate heat exchanger, etc.
[0020] [Evaporator 35] The evaporator 35 heats the working medium RF with steam ST supplied from the gas-liquid separator 10. As the evaporator 35 heats the working medium RF, the working medium RF evaporates and changes from liquid to gas. The evaporator 35 is, for example, a multi-tube heat exchanger. In the evaporator 35, heat exchange occurs between the steam ST and the working medium RF, causing the steam ST to cool. When the steam ST is cooled, it condenses into a condensate HWa.
[0021] Non-condensable gases (NCG) such as carbon dioxide and hydrogen sulfide contained in the steam ST accumulate at the top of the evaporator 35. When non-condensable gases NCG accumulate, the liquid level of the condensate HWa formed from the condensation of steam ST in the evaporator 35 decreases. When the liquid level of the condensate HWa formed from the condensation of steam ST in the evaporator 35 decreases, the heat exchange efficiency between steam ST and the working medium RF in the evaporator 35 decreases. Therefore, it is desirable to discharge the non-condensable gases NCG accumulated in the evaporator 35 from the evaporator 35.
[0022] In the geothermal power plant 1, the non-condensable gas NCG that accumulates in the evaporator 35 is drawn in by the non-condensable gas reduction system 50 and discharged into the reinjection well RWL.
[0023] A level gauge 84 is provided in the evaporator 35. The level gauge 84 measures the liquid level of the condensate HWa that has condensed in the evaporator 35. For example, if non-condensable gas NCG accumulates in the evaporator 35, the liquid level measured by the level gauge 84 will decrease.
[0024] [Cooling section 40] The cooling section 40 supplies coolant CW to cool the working medium RF in the condenser 30. The cooling section 40 is, for example, a cooling tower. The coolant CW1 cooled in the cooling section 40 is sent to the condenser 30 by the pump 93. In the condenser 30, the coolant CW2 whose temperature has risen due to heat exchange with the steam ST is returned to the cooling section 40 and cooled.
[0025] [Non-condensable gas reduction system 50] The non-condensable gas reduction system 50 induces and discharges 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 condensate HWa condensed in the evaporator 35. The condensate HWa is pumped by the pump 92. The ejector 54 discharges a mixture MW, which is a mixture of non-condensable gas NCG and condensate HWa.
[0026] The mixed liquid MW discharged from the ejector 54 is mixed with hot water HW and sent to the reinjection well RWL. The mixed liquid MW and hot water HW sent to the reinjection well RWL are either allowed to flow or blocked by the valve 82.
[0027] 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 a noncondensable gas reduction system 50, which is an example of a noncondensable gas reduction system according to the first embodiment.
[0028] The ejector 54 comprises an induction section 51, a drive nozzle 52, and an expanding 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 condensate HWa is supplied to the drive port 52a of the drive nozzle 52 by the pump 92. As the high-speed condensate HWa 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 condensate HWa. As the non-condensable gas NCG is discharged, the ejector 54 draws in the non-condensable gas NCG.
[0029] The ejector 54 mixes the non-condensable gas NCG and the condensate HW, and discharges the mixed liquid MW through the expanded pipe section 53.
[0030] In ejector 54, the non-condensable gas NCG and condensate HW are mixed and discharged. The resulting mixture MW is then mixed with hot water HW and sent to the reinjection well RWL.
[0031] The ejector 54 is installed on the ground. Installing the ejector 54 on the ground makes maintenance of the ejector 54 easier.
[0032] The control device 58 is primarily composed of a computer, which includes, for example, a processor, a memory or other storage device, an auxiliary storage device, 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).
[0033] When the liquid level measured by the level gauge 84 drops, the control device 58 assumes that non-condensable gas NCG is accumulating in the evaporator 35, opens the valve 83, operates the pump 92, and discharges the non-condensable gas NCG from the ejector 54.
[0034] Specifically, the level gauge 84 measures the liquid level of the condensate HWa formed from the condensation of steam ST in the evaporator 35. The control device 58 then 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 condensate HWa in the evaporator 35, as measured by the level gauge 84, falls below a predetermined 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. Also, when the liquid level of the condensate HWa in the evaporator 35, as measured by the level gauge 84, rises above a predetermined 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] 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 evaporator 35. The valve 83 is located in the flow path of non-condensable gas NCG between the evaporator 35 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 92.
[0036] The control device 58 may also monitor the pressure of the non-condensable gas NCG using the pressure gauge 72.
[0037] [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.
[0038] The control unit 60 controls pumps 91 and 93 respectively. When generating power, the control unit 60 controls pumps 91 and 93 to start. When stopping power generation, the control unit 60 controls pumps 91 and 93 to stop.
[0039] Geothermal power generation emits carbon dioxide as a non-condensable gas, though the amount is far less than that emitted by thermal power generation. For example, 90% of the non-condensable gas contained in the geothermal fluid discharged from production wells is carbon dioxide. In other countries, such as New Zealand, a carbon tax is already imposed on carbon dioxide emissions from geothermal power generation. Similarly, in Japan, the carbon dioxide contained in non-condensable gases could increase the cost of geothermal power generation.
[0040] According to the non-condensable gas reduction system of the first embodiment, by returning the non-condensable gas to the reduction well, it is possible to reduce non-condensable gases such as carbon dioxide emitted into the atmosphere from geothermal power generation.
[0041] Further, according to the non-condensable gas reduction system according to the first embodiment, by using an ejector that is driven by the condensate in which the first gas is condensed in the evaporator to attract the non-condensable gas, for example, the toxicity of hydrogen sulfide contained in the non-condensable gas to the human body and the impact on the natural environment such as the pollution of surrounding plants and soil can be reduced.
[0042] Note that the pressure gauge 71 is an example of the first pressure gauge, the pressure gauge 73 is an example of the second pressure gauge, and the level gauge 84 is an example of the second level gauge.
[0043] <<Second Embodiment>> The non-condensable gas reduction system according to the second embodiment will be described. The non-condensable gas reduction system according to the second embodiment is different from the non-condensable gas reduction system according to the first embodiment in that the third liquid is a part of the coolant sent to the condenser instead of being the condensate in which the first gas is condensed in the evaporator.
[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 a schematic configuration of a geothermal power plant 2 including 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] In the geothermal power plant 2, for the components common to the geothermal power plant 1, the description of the geothermal power plant 1 will be referred to, and the detailed description will be omitted here.
[0047] The non-condensable gas reduction system 150 pressurizes a part of the cooling liquid CW, i.e., the cooling liquid CWa, by a pump 92 and supplies it 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. Also, the control device 158 has the same functions and configuration as the control device 58.
[0048] The ejector 154 is driven by the cooling liquid CWa which is a part of the cooling liquid CW. The cooling liquid CWa is pumped by a pump 92. The ejector 154 discharges a mixed liquid MW obtained by mixing the non-condensable gas NCG and the cooling liquid CWa.
[0049] [[ID=_{6}]]The ejector 154 mixes the non-condensable gas NCG and the cooling liquid CWa and discharges the mixed liquid MW. The mixed liquid MW in which the non-condensable gas NCG and the cooling liquid CWa are mixed and discharged in the ejector 154 is mixed with the hot water HW and the condensate HWa and sent to the reduction well RWL.
[0050] According to the non-condensable gas reduction system according to the second embodiment, similar to the non-condensable gas reduction system according to the first embodiment, by returning the non-condensable gas to the reduction well, non-condensable gases such as carbon dioxide discharged from the geothermal power generation to the atmosphere can be reduced.
[0051] <<Third Embodiment>> The 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, in the non-condensable gas reduction system according to the first embodiment, instead of the third liquid being the condensate in which the first gas condenses in the evaporator, the third liquid is a part of the first liquid.
[0052] Next, the non-condensable gas reduction system according to the third embodiment will be described in detail while referring to the drawings. FIG. 4 is a diagram showing a schematic configuration of a geothermal power plant 3 including 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 comprises 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 comprises valves 81 and 82, and pumps 91 and 93. The control unit 260 has the same functions as the control unit 60.
[0054] For geothermal power plant 3, the configurations common to geothermal power plant 1 should be referred to in the description of geothermal power plant 1, and a detailed explanation will be omitted here.
[0055] The non-condensable gas reduction system 250 pressurizes the hot water HWb, which is part of the hot water HW discharged from the gas-liquid separator 10, using a pump 92 and supplies it to the 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 functions and configuration as the control device 58.
[0056] The ejector 254 is driven by hot water HWb, which is 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 mixture MW, which is a mixture of non-condensable gas NCG and hot water HWb.
[0057] Ejector 254 mixes non-condensable gas NCG with hot water HWb and discharges the mixed liquid MW. The mixed liquid MW, which is discharged after mixing non-condensable gas NCG and hot water HWb in ejector 254, is mixed with hot water HW and condensate HWa and sent to the reinjection well RWL.
[0058] According to the non-condensable gas reduction system of the third embodiment, similar to 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 now be described. The geothermal power plant equipped with the non-condensable gas reduction system according to the fourth embodiment further comprises 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 portion of the first liquid stored in the reduction pit, instead of the third liquid being the condensate obtained by condensing the first gas in the evaporator in the non-condensable gas reduction system according to the first embodiment.
[0060] Next, with reference to the drawings, the non-condensable gas reduction system according to the fourth embodiment will be described in detail. Figure 5 is a schematic diagram of the configuration of a geothermal power plant 4 equipped with a non-condensable gas reduction system 350, which is an example of a non-condensable gas reduction system according to the fourth embodiment.
[0061] The geothermal power plant 4 comprises 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 comprises valves 81 and 82, pumps 91 and 93. Furthermore, the geothermal power plant 4 comprises a reduction pit 311 and a pump 393. The control unit 360 has the same functions as the control unit 60.
[0062] For geothermal power plant 4, the configurations common to geothermal power plant 1 should be referred to in the description of geothermal power plant 1, and a detailed explanation will be omitted here.
[0063] The geothermal power plant 4 is equipped with a reduction pit 311 for storing 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 portion 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] Ejector 354 mixes non-condensable gas NCG with hot water HWc and discharges the mixed liquid MW. The mixed liquid MW, which is discharged after mixing non-condensable gas NCG and hot water HWc in ejector 354, is mixed with hot water HW and sent to the reinjection well RWL.
[0065] The non-condensable gas reduction system 350 pressurizes the hot water HWc, which is part of the hot water HW stored in the reduction pit 311, using a pump 92 and supplies it to the ejector 354. The non-condensable gas reduction system 350 includes an ejector 354, a control device 358, pressure gauges 371, 72 and 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 a pressure gauge 371 instead of a 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 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 mixture MW, which is a mixture of noncondensable gas NCG and hot water HWc.
[0067] Ejector 354 mixes non-condensable gas NCG with hot water HWc and discharges the mixed liquid MW. The mixed liquid MW, which is discharged after mixing non-condensable gas NCG and hot water HWc in ejector 354, is mixed with hot water HW and sent to the reinjection well RWL.
[0068] According to the non-condensable gas reduction system of the fourth embodiment, similar to 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 a non-condensable gas reduction system according to an embodiment of the present disclosure, the determination of the dissolution of non-condensable gas 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 be 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] Figures 6 and 7 illustrate the determination of the dissolution of a noncondensable gas in a noncondensable gas reduction system according to an embodiment of this disclosure. The following description will use ejector 54. The same applies if ejector 154, ejector 254, or ejector 354 is used instead of ejector 54.
[0071] A tank 455 is provided downstream of the ejector 54. A level meter 474 is installed in the tank 455. The level meter 474 measures the level of the liquid stored in the tank 455. The measured result is output to the control device 458. The control device 458 performs a dissolution determination of the non-condensable gas NCG.
[0072] As shown in Figure 7(A), if the non-condensable gas NCG is completely dissolved in the mixed liquid MW, the inside of the tank 455 will be filled with the mixed liquid MW. On the other hand, as shown in Figure 7(B), if the non-condensable gas NCG is not completely dissolved in the mixed liquid MW, the non-condensable gas NCG will accumulate at the top of the tank. Therefore, when the non-condensable gas NCG accumulates, the height measured by the level gauge 474 will decrease by a height ΔL. Thus, by measuring the level of the mixed liquid MW in the tank 455 using the level gauge 474, it is possible to determine whether the non-condensable gas NCG is dissolved in the mixed liquid MW.
[0073] Here, we will describe the process when the non-condensable gas NCG is not dissolved. Figure 8 is a diagram illustrating a first example of the process when the non-condensable gas is not dissolved in a non-condensable gas reduction system according to an embodiment of this disclosure. If the control device 558 determines, based on the level measurement result from the level gauge 474, that the non-condensable gas NCG is not dissolved, it opens a valve 556 provided in the piping connecting the tank 455 and the ejector 54. By opening the valve 556, the non-condensable gas NCG is drawn in from the ejector 54.
[0074] Another example will be described. Figure 9 illustrates a second example of processing when the noncondensable gas is not dissolved in the noncondensable gas reduction system according to the embodiment of this disclosure. In the second example, an additional ejector 650 is provided. A pump 657 is provided to supply a drive flow to the ejector 650. The noncondensable gas NCG accumulated in the tank 455 is discharged from an ejector 650 separate from the ejector 54. If the control device 658 determines, based on the level measurement result from the level gauge 474, that the noncondensable gas NCG is not dissolved, it opens the valve 656 and starts the pump 657 to suck the noncondensable gas NCG from the tank 455 using the ejector 650. The ejector 650 discharges a mixed liquid MW containing the noncondensable gas NCG into the reduction well RWL.
[0075] Furthermore, another example will be described. Figure 10 illustrates a third example of processing when the noncondensable gas is not dissolved in a noncondensable gas reduction system according to an embodiment of the present disclosure. In the third example, a tank 756 for storing a chemical agent is provided. The chemical agent is, for example, an alkaline agent. If the control device 758 determines, based on the level measurement result from the level gauge 474, that the noncondensable gas NCG is not dissolved, it opens the valve 759 between tank 455 and tank 756 and injects the chemical agent into tank 455. The chemical agent is injected, for example, by spraying or pouring it from the top of tank 455.
[0076] The above examples may be combined as appropriate in each of the non-condensable gas reduction systems according to the first to fourth embodiments.
[0077] Furthermore, control devices 458, 558, 658, and 758 have the functions of control devices in the non-condensable gas reduction system according to the first to fourth embodiments.
[0078] Note that 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 now be described. The non-condensable gas reduction system according to the fifth embodiment is equipped with a plurality of ejectors in addition to the non-condensable gas reduction system according to the first embodiment.
[0080] Next, with reference to the drawings, the non-condensable gas reduction system according to the fifth embodiment will be described in detail. Figure 11 is a schematic diagram of the configuration of a geothermal power plant 5 equipped with a non-condensable gas reduction system 850, which is an example of a non-condensable gas reduction system according to the fifth embodiment.
[0081] The geothermal power plant 5 comprises 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 comprises valves 81 and 82, and pumps 91 and 93.
[0082] For geothermal power plant 5, the configurations common to geothermal power plant 1 should be referred to in the description of geothermal power plant 1, and a detailed explanation 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. By having a plurality of ejectors 54, the non-condensable gas reduction system 850 has multiple parallel lines including ejectors 54. By having multiple parallel lines including ejectors 54, maintenance of the ejectors 54 can be performed on some of the lines without stopping the entire non-condensable gas reduction system 850.
[0084] According to the non-condensable gas reduction system of the fifth embodiment, similar to 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. Furthermore, according to the non-condensable gas reduction system of the fifth embodiment, maintainability can be improved by providing multiple ejectors, for example, by switching between them during operation.
[0085] In the example shown in Figure 11, a geothermal power plant 5 having a similar configuration to 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, was used as an example for explanation. However, the explanation is not limited to the non-condensable gas reduction system according to the first embodiment. A geothermal power plant equipped with a non-condensable gas reduction system according to any of the second to fourth embodiments may also be equipped with multiple lines including ejectors. Furthermore, in the non-condensable gas reduction system according to the fifth embodiment, processing may be performed when the non-condensable gas described above is not dissolved.
[0086] 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.
[0087] This application claims priority to Basic Patent Application No. 2025-018086, filed with the Japan Patent Office on February 6, 2025, the entire contents of which are incorporated herein by reference.
[0088] 1, 2, 3, 4, 5 Geothermal power plant 10 Gas-liquid separator 20 Power generation section 21 Turbine 22 Generator 30 Condenser 35 Evaporator 40 Cooling section 50, 150, 250, 350, 850 Non-condensable gas reduction system 51 Induction section 51a Induction port 52 Drive nozzle 52a Drive port 53 Expanding section 54, 154, 254, 354, 650 Ejector 58, 158, 258, 358, 458, 558, 658, 758, 858 Control device 60, 160, 260, 360, 860 Control unit 71, 72, 73, 371 Pressure gauge 81, 82, 83, 556, 656, 759 Valve 91, 92, 93, 393, 657 Pumps 311 Reduction pits 455, 756 Tanks 84, 474 Level gauges CW, CW1, CW2, CWa Coolant GF Geothermal fluid HWa Condenser HW, HWb, HWc Hot water MW Mixture NCG Non-condensable gas PWL Production well RWL Reduction well ST Steam
Claims
1. A non-condensable gas reduction system for use in a geothermal power plant, comprising: a gas-liquid separator for separating geothermal fluid gushing from a production well into a first gas and a first liquid; an evaporator for heat exchange between the first gas and a working medium; a turbine rotated by the working medium discharged from the evaporator; and a condenser for cooling the working medium that has rotated the turbine and for condensing the working medium into a liquid, wherein the system further comprises: a pump for pressurizing a third liquid sent to a reduction well; and an ejector driven by the third liquid for inducing non-condensable gas contained in the first gas that remains uncondensed in the evaporator, and for discharging a fourth liquid in which the third liquid and the non-condensable gas are mixed, the first liquid and the fourth liquid being mixed and sent to the reduction well.
2. The non-condensable gas reduction system according to claim 1, wherein the third liquid is a condensate obtained by condensing the first gas in the evaporator.
3. The non-condensable gas reduction system according to claim 1, wherein the third liquid is part of the coolant supplied to the condenser.
4. The non-condensable gas reduction system according to claim 1, wherein the third liquid is a part of the first liquid.
5. The non-condensable gas reduction system according to claim 1, wherein the geothermal power plant further comprises a reduction pit for storing the first liquid, and the third liquid is a portion of the first liquid stored in the reduction pit.
6. The ejector is installed on the ground in the non-condensable gas reduction system according to any one of claims 1 to 5.
7. A noncondensable gas reduction system according to any one of claims 1 to 5, further comprising: a tank connected downstream of the ejector; a first level meter for measuring the level of the liquid stored in the tank; and a control device, wherein the control device performs a determination of the dissolution of the noncondensable gas in the fourth liquid according to the level measured by the first level meter.
8. The noncondensable gas reduction system according to claim 7, wherein the control device determines that the noncondensable gas is not dissolved in the fourth liquid, and controls the discharge of the noncondensable gas accumulated in the tank from the ejector.
9. The noncondensable gas reduction system according to claim 7, wherein the control device determines that the noncondensable gas is not dissolved in the fourth liquid, and controls the discharge of the noncondensable gas accumulated in the tank to the reduction well from an ejector different from the ejector.
10. The non-condensable gas reduction system according to claim 7, wherein the control device controls the injection of a chemical agent into the tank when it determines that the non-condensable gas is not dissolved in the fourth liquid.
11. A non-condensable gas reduction system according to any one of claims 1 to 5, further comprising: a first pressure gauge for measuring the pressure of the first liquid; a second pressure gauge for measuring the pressure of the third liquid; a valve provided in the flow path between the evaporator and the ejector; and a control device, wherein the control device shuts off the valve when the pressure of the first liquid measured by the first pressure gauge is higher than the pressure of the third liquid measured by the second pressure gauge.
12. A non-condensable gas reduction system according to any one of claims 1 to 5, further comprising: a second level meter for measuring the liquid level of the condensate obtained by condensing the first gas in the evaporator; a valve provided in the flow path between the evaporator and the ejector; and a control device, wherein the control device controls the opening and closing of the valve according to the level measured by the second level meter.