Non-condensable gas reduction 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 JP2025028018_13082026_PF_FP_ABST
Abstract
Description
Non-condensable Gas Reduction System
[0001] The present disclosure relates to a non-condensable gas reduction system.
[0002] In Patent Document 1, a method for disposing of non-condensable gas generated in a geothermal power generation facility is disclosed, 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 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 Application Laid-Open No. 9-177507 Japanese Patent Application 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 condenser or evaporator directly below the turbine, causing a decrease in the degree of vacuum and a decrease in heat exchange efficiency. In order to prevent a decrease in the degree of vacuum and a decrease in heat exchange efficiency, the non-condensable gas is removed by an extractor or the like. The extracted non-condensable gas is sent from, for example, the condenser or evaporator to a cooling tower, mixed with air, and discharged 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] The present disclosure is a non-condensable gas reduction system used in a geothermal power plant including a gas-liquid separator that separates geothermal fluid gushing out from a production well into a first gas and a first liquid, a turbine rotated by the first gas, and a condenser that cools the first gas rotated by the turbine and condenses steam contained in the first gas into a second liquid, and includes a pump that pressurizes a third liquid sent to a reduction well, and an ejector that is driven by the third liquid, attracts non-condensable gas contained in the first gas and remaining uncondensed in the condenser, and discharges a fourth liquid in which the third liquid and the non-condensable gas are mixed, and provides 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 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 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 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 8 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 9 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 10 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 11 is a schematic diagram of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the fifth embodiment. Figure 12 is a schematic diagram of the configuration of a geothermal power plant equipped with a non-condensable gas reduction system according to the sixth 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 a turbine that rotates with respect to the first gas. The geothermal power plant using the non-condensable gas reduction system according to the first embodiment also includes a condenser that cools the first gas that has rotated the turbine and condenses the steam contained in the first gas into a second liquid. 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 condenser, and discharges a fourth liquid which is a mixture of the third liquid and the non-condensable gas. 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 part of the coolant sent to the condenser.
[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, 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 flash-type geothermal power plant. The geothermal power plant 1 also comprises valves 81 and 82 and a pump 91.
[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 power generation unit 20. The hot water HW discharged from the gas-liquid separator 10 is discharged to 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 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 in the condenser 30 by the condensation of water vapor contained in the steam ST. 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 supplied from the cooling unit 40, more specifically, with coolant CW1. The condenser 30 is a so-called surface contact type 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 (second liquid). In the condenser 30, which is a surface contact type condenser, 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 (NCGs) 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 (NCGs) accumulated in the condenser 30 from the condenser 30.
[0020] In the 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 section 40 supplies coolant CW to cool the steam ST 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 91. In the condenser 30, the coolant CW2 whose temperature has risen due to heat exchange with the steam ST returns to the cooling section 40 and is cooled.
[0022] [Non-condensable gas reduction system 50] The non-condensable gas reduction system 50 induces and discharges non-condensable gas NCG from the condenser 30. 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 coolant CW, more specifically by coolant CWa, which is a part of coolant CW1. Coolant CWa is pumped by the pump 92. The ejector 54 discharges a mixture MW, which is a mixture of non-condensable gas NCG and coolant CWa.
[0023] 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.
[0024] 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.
[0025] 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 coolant CWa is supplied to the drive port 52a of the drive nozzle 52 by the pump 92. 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 CW are mixed and discharged. The resulting mixture MW is then mixed with hot water HW and 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.
[0029] 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).
[0030] 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 92.
[0031] The control device 58 may also monitor the pressure of the non-condensable gas NCG using the pressure gauge 72.
[0032] [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.
[0033] 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.
[0034] Geothermal power generation emits carbon dioxide as a non-condensable gas, though far less than 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 the carbon dioxide emitted from geothermal power generation. Similarly, in Japan, the carbon dioxide contained in non-condensable gases could increase the cost of geothermal power generation.
[0035] 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.
[0036] Furthermore, according to the non-condensable gas reduction system of the first embodiment, by using an ejector driven by a coolant to induce non-condensable gases, it is possible to reduce the impact on the natural environment, such as the toxicity of hydrogen sulfide contained in the non-condensable gases to the human body and the contamination of surrounding plants and soil.
[0037] Note that pressure gauge 71 is an example of a first pressure gauge, and pressure gauge 73 is an example of a second pressure gauge.
[0038] ≪Second Embodiment≫ A non-condensable gas reduction system according to the second embodiment will now be described. In the non-condensable gas reduction system according to the second embodiment, the third liquid is a part of the first liquid, instead of being a part of the coolant sent to the condenser in the non-condensable gas reduction system according to the first embodiment.
[0039] Next, with reference to the drawings, the non-condensable gas reduction system according to the second embodiment will be described in detail. Figure 3 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.
[0040] The geothermal power plant 2 comprises a gas-liquid separator 10, a power generation unit 20, a condenser 30, a cooling unit 40, a non-condensable gas reduction system 150, and a control unit 160. The geothermal power plant 2 also comprises valves 81 and 82, and a pump 91. The control unit 160 has the same functions as the control unit 60.
[0041] Regarding the configuration of geothermal power plant 2 that is common to geothermal power plant 1, please refer to the description of geothermal power plant 1, and a detailed explanation will be omitted here.
[0042] The non-condensable gas reduction system 150 pressurizes the hot water HWa, 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 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 functions and configuration as the control device 58.
[0043] The ejector 154 is driven by the hot water HWa, which is a part of the hot water HW discharged from the gas-liquid separator 10. The hot water HWa is pumped by the pump 92. The ejector 154 discharges a mixed liquid MW obtained by mixing the non-condensable gas NCG and the hot water HWa.
[0044] The ejector 154 mixes the non-condensable gas NCG and the hot water HWa and discharges the mixed liquid MW. The mixed liquid MW in which the non-condensable gas NCG and the hot water HWa are mixed and discharged in the ejector 154 is mixed with the hot water HW and sent to the reinjection well RWL.
[0045] 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 reinjection well, non-condensable gases such as carbon dioxide discharged from geothermal power generation to the atmosphere can be reduced.
[0046] ≪Third Embodiment≫ A non-condensable gas reduction system according to the third embodiment will be described. A geothermal power plant equipped with the non-condensable gas reduction system according to the third embodiment further includes a reduction pit for storing the first liquid. And the non-condensable gas reduction system according to the third embodiment is a part of the first liquid stored in the reduction pit, instead of a part of the coolant in which the third liquid is sent to the condenser in the non-condensable gas reduction system according to the first embodiment.
[0047] Next, with reference to the drawings, the non-condensable gas reduction system according to the third embodiment will be described in detail. FIG. 4 is a diagram showing an outline of the configuration in 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.
[0048] The geothermal power plant 3 includes a gas-liquid separator 10, a power generation unit 20, a condenser 30, 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, pumps 91 and 293, and a reduction pit 211. The control unit 260 has the same functions as the control unit 60.
[0049] 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.
[0050] The geothermal power plant 3 is equipped with a reduction pit 211 for storing hot water HW discharged from the gas-liquid separator 10. The hot water HW stored in the reduction pit 211 is sent to the reduction well RWL by a pump 293. In addition, hot water HWb, which is a portion of the hot water HW stored in the reduction pit 211, is pressurized by a pump 92 and supplied to the ejector 254. The reduction pit 211 may be a tank or a pool.
[0051] The non-condensable gas reduction system 250 includes an ejector 254, a control device 258, pressure gauges 271, 72, and 73, a valve 83, and a pump 92. The non-condensable gas reduction system 250 measures the pressure P1 of the hot water HW using the pressure gauge 271, instead of the pressure gauge 71 in the non-condensable gas reduction system 50. 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. The non-condensable gas reduction system 250 pressurizes the hot water HWb, which is part of the hot water HW stored in the reduction pit 211, with the pump 92 and supplies it to the ejector 254.
[0052] The ejector 254 is driven by hot water HWb, which is part of the hot water HW stored in the reduction pit 211. The hot water HWb is pumped by the pump 92. The ejector 254 discharges a mixture MW, which is a mixture of noncondensable gas NCG and hot water HWb.
[0053] 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 sent to the reinjection well RWL.
[0054] 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.
[0055] ≪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.
[0056] Figures 5 and 6 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 as an example. The same applies if ejector 154 or ejector 254 is used instead of ejector 54.
[0057] A tank 355 is provided downstream of the ejector 54. A level gauge 374 is installed in the tank 355. The level gauge 374 measures the level of the liquid stored in the tank 355. The measured result is output to the control device 358. The control device 358 performs a dissolution determination of the non-condensable gas NCG.
[0058] As shown in Figure 6(A), if the non-condensable gas NCG is completely dissolved in the mixed liquid MW, the inside of the tank 355 will be filled with the mixed liquid MW. On the other hand, as shown in Figure 6(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 374 will decrease by a height ΔL. Thus, by measuring the level of the mixed liquid MW in the tank 355 using the level gauge 374, it is possible to determine whether the non-condensable gas NCG is dissolved in the mixed liquid MW.
[0059] Here, we will describe the process when the non-condensable gas NCG is not dissolved. Figure 7 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 458 determines, based on the level measurement result from the level gauge 374, that the non-condensable gas NCG is not dissolved, it opens a valve 356 provided in the piping connecting the tank 355 and the ejector 54. By opening the valve 356, the non-condensable gas NCG is drawn in from the ejector 54.
[0060] Another example will be described. Figure 8 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 550 is provided. A pump 557 is provided to supply a drive flow to the ejector 550. The noncondensable gas NCG accumulated in the tank 355 is discharged from an ejector 550 separate from the ejector 54. If the control device 558 determines, based on the level measurement result from the level gauge 374, that the noncondensable gas NCG is not dissolved, it opens the valve 556 and starts the pump 557 to suck the noncondensable gas NCG from the tank 355 using the ejector 550. The ejector 550 discharges a mixed liquid MW containing the noncondensable gas NCG into the reduction well RWL.
[0061] Furthermore, another example will be described. Figure 9 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 656 for storing a chemical agent is provided. The chemical agent is, for example, an alkaline agent. If the control device 658 determines, based on the level measurement result from the level gauge 374, that the noncondensable gas NCG is not dissolved, it opens the valve 659 between tank 355 and tank 656 and injects the chemical agent into tank 355. The chemical agent is injected, for example, by spraying or pouring it from the top of tank 355.
[0062] The above examples may be combined as appropriate in each of the non-condensable gas reduction systems according to the first to third embodiments.
[0063] Control devices 358, 458, 558, and 658 have the functions of control devices in the non-condensable gas reduction system according to the first to third embodiments.
[0064] <Fourth Embodiment> A non-condensable gas reduction system according to the fourth embodiment will now be described. The non-condensable gas reduction system according to the fourth embodiment is equipped with a plurality of ejectors in addition to the non-condensable gas reduction system according to the first embodiment.
[0065] Next, with reference to the drawings, the non-condensable gas reduction system according to the fourth embodiment will be described in detail. Figure 10 is a schematic diagram of the configuration of a geothermal power plant 4 equipped with a non-condensable gas reduction system 750, which is an example of a non-condensable gas reduction system according to the fourth embodiment.
[0066] The geothermal power plant 4 comprises a gas-liquid separator 10, a power generation unit 20, a condenser 30, a cooling unit 40, a non-condensable gas reduction system 750, a control unit 760, and a pump 91.
[0067] 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.
[0068] The non-condensable gas reduction system 750 includes a plurality of ejectors 54, a control device 758, 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 750 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 750.
[0069] 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. Furthermore, according to the non-condensable gas reduction system of the fourth embodiment, maintainability can be improved by providing multiple ejectors, for example, by switching between them during operation.
[0070] In the example shown in Figure 10, a geothermal power plant 4 having a configuration similar to that of 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 the second or third embodiment may also be equipped with multiple lines including ejectors. Furthermore, in the non-condensable gas reduction system according to the fourth embodiment, processing may be performed when the non-condensable gas described above is not dissolved. The same applies to the following embodiments.
[0071] <Fifth Embodiment> A non-condensable gas reduction system according to the fifth embodiment will now be described. In the non-condensable gas reduction system according to the fifth embodiment, the third liquid is a liquid containing the second liquid, instead of the third liquid being a part of the coolant sent to the condenser in the non-condensable gas reduction system according to the first embodiment.
[0072] 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.
[0073] The geothermal power plant 5 comprises a gas-liquid separator 10, a power generation unit 20, a condenser 30, 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 a pump 91. The control unit 860 has the same functions as the control unit 60.
[0074] 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.
[0075] The non-condensable gas reduction system 850 pressurizes the condensate HWc (second liquid) of the steam ST condensed in the condenser 30 using a pump 92 and supplies it to the ejector 854. The non-condensable gas reduction system 850 includes an ejector 854, a control device 858, pressure gauges 71, 72, and 73, a valve 83, and a pump 92. The ejector 854 has the same configuration as the ejector 54. The control device 858 has the same functions and configuration as the control device 58.
[0076] The ejector 854 is driven by the condensate HWc of the steam ST condensed in the condenser 30. The condensate HWc is pumped by the pump 92. The ejector 854 discharges a mixture MW, which is a mixture of non-condensable gas NCG and condensate HWc.
[0077] Ejector 854 mixes the non-condensable gas NCG with the condensate HWc and discharges the mixed liquid MW. The mixed liquid MW, which is discharged after mixing the non-condensable gas NCG and the condensate HWc in ejector 854, is mixed with hot water HW and sent to the reinjection well RWL.
[0078] 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.
[0079] <<Sixth Embodiment>> A non-condensable gas reduction system according to the sixth embodiment will now be described. In the non-condensable gas reduction system according to the sixth embodiment, the third liquid is a part of the coolant sent to the condenser, whereas in the non-condensable gas reduction system according to the first embodiment the third liquid is a part of the coolant sent to the condenser.
[0080] Next, with reference to the drawings, the non-condensable gas reduction system according to the sixth embodiment will be described in detail. Figure 12 is a schematic diagram of the configuration of a geothermal power plant 6 equipped with a non-condensable gas reduction system 950, which is an example of a non-condensable gas reduction system according to the sixth embodiment.
[0081] The geothermal power plant 6 comprises a gas-liquid separator 10, a power generation unit 20, a condenser 930, a cooling unit 940, a non-condensable gas reduction system 950, and a control unit 960. The geothermal power plant 6 also comprises valves 81 and 82, and pumps 91 and 932. The control unit 960 has the same functions as the control unit 60.
[0082] For geothermal power plant 6, 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] [Condenser 930] The condenser 930 cools the steam ST discharged from the turbine 21 with coolant CWA supplied from the cooling unit 940, more specifically, coolant CWA1. The condenser 930 is a so-called direct-contact condenser. The condenser 930 is equipped with a nozzle section 931. The nozzle section 931 is equipped with multiple nozzles that spray the coolant CWA1 as a mist. The nozzle section 931 may be equipped with just one nozzle. The condenser 930 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 (second liquid) as it is cooled in the condenser 930. In the condenser 930, which is a direct-contact condenser, the coolant CWA1 is in direct contact with the steam ST. The coolant CWA2 contains water (second liquid) formed from condensed vapor ST.
[0084] [Cooling section 940] The cooling section 940 supplies the coolant CWA to cool the steam ST in the condenser 930. The cooling section 940 is a cooling tower. Pump 932 sends the coolant CWA2, which has become hot after cooling the steam ST in the condenser 930, to the cooling section 940. The cooling section 940 cools the coolant CWA2. The coolant CWA cooled in the cooling section 940 is sent to the condenser 930 by pump 91. In the condenser 930, the coolant CWA2, whose temperature has risen due to heat exchange with the steam ST, returns to the cooling section 940 and is cooled.
[0085] The cooling section 940 is a forced-air wet cooling tower. The cooling section 940 brings the coolant CWA2 into direct contact with air. The cooling section 940 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 section 940 is a suction-type counterflow cooling tower.
[0086] The cooling unit 940 comprises a fan 941, a nozzle unit 942, and a packing material 943. The fan 941 discharges outside air taken into the interior through the opening 940h. The nozzle unit 942 has multiple nozzles that spray the coolant CWA2 sent from the condenser 930 as a mist onto the packing material 943. The nozzle unit 942 may have just one nozzle.
[0087] As air passes through the gaps in the filler material 943, the coolant CWA2 sprayed from the nozzle 942 exchanges heat with the air.
[0088] The coolant CWA cooled in the cooling unit 940 is supplied to the condenser 930 by the pump 91.
[0089] In the example described above, the cooling section 940 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.
[0090] [Non-condensable gas reduction system 950] The non-condensable gas reduction system 950 induces and discharges non-condensable gas NCG from the condenser 930. The non-condensable gas reduction system 950 is driven by coolant CWA, more specifically coolant CWAa, which is a part of coolant CWA1. Coolant CWAa is pumped by pump 92. The ejector 954 discharges a mixed liquid MW, which is a mixture of non-condensable gas NCG and coolant CWAa. The non-condensable gas reduction system 950 comprises the ejector 954, a control device 958, pressure gauges 71, 72, and 73, a valve 83, and a pump 92. The ejector 954 has the same configuration as the ejector 54. The control device 958 has the same function and configuration as the control device 58.
[0091] The ejector 954 is driven by coolant CWAa, which is part of the coolant CWA1. Coolant CWAa contains water (second liquid) condensed from steam ST in the condenser 930. Coolant CWAa is pumped by pump 92. The ejector 954 discharges a mixture MW, which is a mixture of non-condensable gas NCG and coolant CWAa.
[0092] Ejector 954 mixes non-condensable gas NCG with coolant CWAa and discharges the mixed liquid MW. The mixed liquid MW, which is discharged after mixing non-condensable gas NCG and coolant CWAa in ejector 954, is mixed with hot water HW and sent to the reinjection well RWL.
[0093] According to the non-condensable gas reduction system of the sixth 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.
[0094] 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.
[0095] This application claims priority to Basic Patent Application No. 2025-018146, filed with the Japan Patent Office on February 6, 2025, the entire contents of which are incorporated herein by reference.
[0096] 1, 2, 3, 4, 5, 6 Geothermal power plant 10 Gas-liquid separator 20 Power generation section 21 Turbine 22 Generator 30, 930 Condenser 40, 940 Cooling section 50, 150, 250, 750, 850, 950 Non-condensable gas reduction system 51 Induction section 51a Induction port 52 Drive nozzle 52a Drive port 53 Pipe expansion section 54, 154, 254, 550, 854, 954 Ejector 58, 158, 258, 358, 458, 558, 658, 758, 858, 958 Control device 60, 160, 260, 760, 860, 960 Control unit 71, 72, 73, 271 Pressure gauge 81, 82, 83, 356, 556, 659 Valves 91, 92, 293, 557, 932 Pumps 211 Reduction pits 355, 656 Tanks 374 Level gauges CW, CW1, CW2, CWa, CWA, CWA1, CWA2, CWAa Coolant GF Geothermal fluid HW, HWa, HWb Hot water HWc Condenser 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; a turbine rotated by the first gas; and a condenser for cooling the first gas that has rotated the turbine and for condensing the steam contained in the first gas into a second liquid, wherein the system comprises: a pump for pressurizing a third liquid sent to a reinjection well; and an ejector driven by the third liquid for inducing non-condensable gas contained in the first gas that remains uncondensed in the condenser, and for discharging 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.
2. The non-condensable gas reduction system according to claim 1, wherein the third liquid is part of the coolant supplied to the condenser.
3. The non-condensable gas reduction system according to claim 1, wherein the third liquid is a part of the first liquid.
4. 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.
5. The non-condensable gas reduction system according to claim 1, wherein the third liquid includes the second liquid.
6. The non-condensable gas reduction system according to claim 1, wherein the third liquid is part of the coolant supplied to the condenser containing the second liquid.
7. The ejector is installed on the ground in the non-condensable gas reduction system according to any one of claims 1 to 6.
8. A noncondensable gas reduction system according to any one of claims 1 to 6, further comprising: a tank connected downstream of the ejector; a 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 level meter.
9. The noncondensable gas reduction system according to claim 8, wherein the control device determines that the noncondensable gas is not dissolved in the fourth liquid, and controls the ejector to discharge the noncondensable gas accumulated in the tank.
10. The noncondensable gas reduction system according to claim 8, 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.
11. The non-condensable gas reduction system according to claim 8, 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.
12. A non-condensable gas reduction system according to any one of claims 1 to 6, 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 condenser 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.