Geothermal power generation system

Abstract

A geothermal power generation system including a binary power generation device having a medium evaporator comprises: a gas-liquid separator that separates geothermal water from geothermal fluid ejected from a production well; first piping that sends the geothermal water separated by the gas-liquid separator to the medium evaporator; a first valve that is provided to the first piping and opens and closes a flow path of the first piping; second piping that sends the geothermal water from which heat has been recovered by the binary power generation device from the medium evaporator to a reinjection well; an analysis device into which the geothermal water flowing through the second piping flows and which analyzes components of scale included in the inflow geothermal water; and a control device that determines at least one type of cleaning agent from among a plurality of types of cleaning agent candidates on the basis of the analysis result of the analysis device, and performs control to supply the selected cleaning agent, wherein the first piping has a cleaning agent supply port to which the cleaning agent is supplied on the downstream side of the first valve.

Description

Geothermal Power Generation System

[0001] The present invention relates to a geothermal power generation system.

[0002] Geothermal power generation systems extract high-temperature geothermal fluids (hot water and geothermal steam) from production wells and generate electricity using the steam separated from the geothermal fluid. Geothermal fluids extracted from production wells contain more calcium and dissolved silica than well water or river water.

[0003] Dissolved silica in geothermal water collected from production wells is concentrated by reducing pressure in geothermal power generation systems, and is cooled as it flows through the pipes, reducing its solubility. When the silica and dissolved silica contained in the geothermal water become supersaturated, they polymerize to form calcium carbonate and amorphous silica, which precipitate as scale. The scale adheres to the inner walls of the pipes, potentially causing blockages and other problems, making scale deposition a problem in geothermal power generation systems.

[0004] In particular, binary geothermal power generation systems are required to thoroughly clean the scale. For example, Patent Document 1 discloses a binary geothermal power generation system in which hydrogen peroxide solution is supplied as an oxidizing agent to geothermal water upstream of the evaporator in the geothermal water outlet line to prevent the buildup of silica scale in the geothermal water system.

[0005] JP 2015-90147 A

[0006] However, the scale contained in geothermal water in geothermal power generation systems contains multiple components, such as silica, calcium, sludge, and iron filings, and its composition varies from power plant to power plant. Furthermore, even at the same power plant, the composition can change over long periods of operation. Therefore, while conventional geothermal power generation systems can clean scale primarily composed of silica, cleaning of scale primarily composed of other components is insufficient, resulting in poor cleaning.

[0007] One aspect of the present invention provides a geothermal power generation system that can remove scale regardless of the components of the scale.

[0008] One aspect of the present invention is a geothermal power generation system including a binary power generation device with a media evaporator, the system comprising: a gas-liquid separator that separates geothermal water from geothermal fluid gushes out from a production well; a first pipe that sends the geothermal water separated by the gas-liquid separator to the media evaporator; a first valve that is provided in the first pipe and opens and closes a flow path of the first pipe; a second pipe that sends the geothermal water that has undergone heat recovery by the binary power generation device from the media evaporator to an injection well; an analyzer that receives the geothermal water flowing through the second pipe and analyzes components of scale contained in the inflowing geothermal water; and a control device that determines at least one cleaning agent from multiple candidate cleaning agents based on analysis results of the analyzer and controls supply of the cleaning agent, and the first pipe has a cleaning agent supply port downstream of the first valve through which the cleaning agent is supplied.

[0009] According to a geothermal power generation system according to one aspect of the present invention, scale can be removed regardless of the components of the scale.

[0010] It is a schematic diagram of a geothermal power generation system according to one embodiment. It is a schematic diagram of a separation vessel. It is a flow chart for explaining a cleaning method according to one embodiment.

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a schematic diagram of a geothermal power generation system 1 according to one embodiment. As shown in FIG. 1 , the geothermal power generation system 1 includes a binary power generation unit 20 having a medium evaporator 21. The geothermal power generation system 1 also includes a gas-liquid separator 3, a first pipe L1 that sends geothermal water separated in the gas-liquid separator 3 to the medium evaporator 21, a first valve V1 that is provided in the first pipe L1 and that opens and closes the flow path of the first pipe L1, and a second pipe L2 that sends geothermal water that has undergone heat recovery in the binary power generation unit 20 from the medium evaporator 21 to a reinjection well 4. The geothermal power generation system 1 also includes an analyzer 30 and a controller 40. The first pipe L1 also includes a cleaning agent supply port 5, through which a cleaning agent is supplied, downstream of the first valve V1.

[0013] The geothermal power generation system 1 generates binary power in a binary power generation device 20 by utilizing the heat of the geothermal water separated in the gas-liquid separator 3. In the geothermal power generation system 1, geothermal fluid collected from the production well 2 is sent to the gas-liquid separator 3. The gas-liquid separator 3 separates the geothermal water from the geothermal fluid that gushes out from the production well 2. The geothermal water separated in the gas-liquid separator 3 is sent to the medium evaporator 21 via a first pipe L1, where it is heat exchanged to evaporate the low-boiling-point heat medium, and then returned to the reinjection well 4 via a second pipe L2.

[0014] The heat medium vaporized in the medium evaporator 21 is sent to a turbine 22 via a pipe, and electricity is generated by a generator 23. Furthermore, the heat medium that has passed through the turbine 22 is sent to a medium condenser 24 via a pipe, where it becomes a condensed liquid, and is returned to the medium evaporator 21 via a pipe having a pump 25 provided midway.

[0015] The heat medium used in the binary power generation device 20 is a low-boiling-point heat medium that can be vaporized using the heat of the geothermal water separated in the gas-liquid separator 3. The heat medium is not particularly limited, but examples thereof include normal heptane, isoheptane, normal pentane, isopentane, normal butane, isobutane, hydrofluoroether, 1,1,1,3,3-pentafluoropropane (R245fa), 1,1,1,2-tetrafluoroethane (R134a), chlorodifluoromethane (R22), difluoromethane, 1,1,1,2-pentafluoroethane, and a mixture of 1,1,1,2-tetrafluoroethane (R407c).

[0016] On the other hand, the geothermal steam separated by the gas-liquid separator 3 may be sent to a turbine (not shown) and electricity may be generated by a generator connected to the turbine. In this case, the gas-liquid separator 3 functions as a flasher that reduces the pressure of the geothermal water to extract geothermal steam. In other words, the geothermal power generation system 1 may include a flash power generation device (not shown) connected to the gas-liquid separator 3 and a binary power generation device 20.

[0017] The geothermal power generation system 1 may include a thirteenth pipe L13 that branches off from the first pipe L1 and connects to the reinjection well 4, and a bypass valve V11 provided midway between the thirteenth pipe L13 and the reinjection well 4.

[0018] The geothermal power generation system 1 may include: a second valve V2 provided in the second pipe L2 for opening and closing the flow path of the second pipe L2; a third pipe L3 connected to the second pipe L2 upstream of the second valve V2; and a branch unit 6 capable of branching the flow of geothermal water or cleaning agent flowing through the third pipe L3 into an analysis line L11 connected to the analysis device 30 and a cleaning agent supply line L12 connected to the cleaning agent supply port 5. The geothermal power generation system 1 may also include a cleaning agent addition device 50 that adds a cleaning agent to the geothermal water flowing through the third pipe L3. Note that FIG. 1 shows a state in which the first valve V1 and the second valve V2 are closed.

[0019] The inner diameter of the analysis line L11 is smaller than the inner diameter of the cleaning agent supply line L12. This allows geothermal water at a flow rate appropriate for analysis, which is smaller than the flow rate of the geothermal water flowing into the analysis line L11, to be introduced into the analysis device 30 via the analysis line L11, and allows the cleaning agent at a flow rate necessary for cleaning to be introduced into the cleaning agent supply line L12.

[0020] The geothermal power generation system 1 may include a circulation pump 12 provided in the first pipe L1 downstream of the cleaning agent supply port 5. The circulation pump 12 has a function of sending the geothermal water separated in the gas-liquid separator 3 to the second pipe L2 during normal operation (during power generation), and has a function of circulating the cleaning agent supplied from the cleaning agent supply port 5 together with the geothermal water through a flow path consisting of the first pipe L1, the second pipe L2, the third pipe L3, and the cleaning agent supply line L12 when cleaning is performed after normal operation is stopped (after power generation is stopped).

[0021] Preferably, the geothermal power generation system 1 further includes a third valve V3 that is provided in the cleaning agent supply line L12 and opens and closes the flow path of the cleaning agent supply line L12. Specifically, the cleaning agent supply line L12 has a first cleaning agent supply line L12a that branches off from the branching portion 6, and a second cleaning agent supply line L12b that has one end connected to the first cleaning agent supply line L12a and the other end connected to the cleaning agent supply port 5. The third valve V3 is provided in the first cleaning agent supply line L12a.

[0022] The geothermal power generation system 1 may be provided with a fourth pipe L4, one end of which is connected to the first outlet 34 of the analytical device 30 and the other end of which is connected to the second cleaning agent supply line L12b, for circulating the geothermal water discharged from the analytical device 30.

[0023] The analysis device 30 receives the geothermal water flowing through the second pipe L2 and analyzes the scale components contained in the geothermal water that has flowed in. Examples of scale components contained in the geothermal water include amorphous silica, calcium carbonate, soft mud containing organic matter, and iron rust.

[0024] As shown in Figure 2, the analysis device 30 may have a separation container 31 that separates the geothermal water that flows into the analysis device 30 into solids, liquids, or gases, a gas analyzer 32 that analyzes the gas separated from the separation container 31, and a liquid analyzer 33 that analyzes the liquid separated from the separation container 31.

[0025] The separation vessel 31 may generate a swirling flow therein to separate solids, liquids, or gases contained in the geothermal water. In Figure 2, the flow of solids, liquids, or gases contained in the geothermal water is indicated by arrows. Specifically, the separation vessel 31 may have a cylindrical shape and include a housing 311 arranged so that its axis 310 is at an angle of 0° or more and less than 90° with respect to the vertical direction, a geothermal water inlet 312 provided on the side of the housing 311 through which the geothermal water flows in, and a geothermal water outlet 313 through which the geothermal water is discharged.

[0026] The geothermal water inlet 312 is connected to the analytical line L11, and the geothermal water outlet 313 is connected to the fourth pipe L4. The geothermal power generation system 1 may include a fifth valve V5 provided in the analytical line L11 to open and close the flow path of the analytical line L11, and a sixth valve V6 provided in the fourth pipe L4 to open and close the flow path of the fourth pipe L4.

[0027] The geothermal power generation system 1 may include a flow meter 9 provided in the analysis line L11 to measure the flow rate of the geothermal water flowing into the analysis device 30.

[0028] The interior of the separation container 31 may be divided into three chambers. For example, the separation container 31 may have a first chamber R1, a second chamber R2, and a third chamber R3, which are arranged adjacent to each other in this order from the top in the vertical direction. The first chamber R1, the second chamber R2, and the third chamber R3 are connected at the center. Specifically, the separation container 31 includes two partitions 318 each having an opening 317 at the center, and the partitions 318 may be arranged spaced apart along an axis 310 inside the housing 311. The central axis of the opening 317 coincides with the axis 310 of the housing 311. The partitions 318 may be, for example, a baffle.

[0029] The first chamber R1 is provided on the top surface and has a gas outlet 314 for discharging separated gas. The second chamber R2 is provided on the side surface and has a first solid outlet 315 for discharging separated solids. The third chamber R3 is provided on the bottom surface of the separation vessel 31 and has a second solid outlet 319 for discharging separated solids and a liquid outlet 316 on the side surface and for discharging liquid.

[0030] The solids discharged from the first solid discharge outlet 315 are solids with a relatively large mass, such as rock fragments and iron rust, while the solids discharged from the second solid discharge outlet 319 are solids with a smaller mass than the solids discharged from the first solid discharge outlet 315, such as soft mud and colloids.

[0031] The geothermal water inlet 312 and the geothermal water outlet 313 are provided on the side of the second chamber R2, and the geothermal water inlet 312 is positioned vertically lower than the geothermal water outlet 313. With the above configuration, the separation vessel 31 can generate a swirling flow inside to separate solids, liquids, or gases contained in the geothermal water.

[0032] The gas analyzer 32 is connected to the gas outlet 314 of the separation vessel 31. The gas analyzer 32 measures, for example, the concentration of oxygen and the concentration of carbon dioxide.

[0033] The liquid analyzer 33 is connected to the liquid outlet 316 of the separation container 31. The liquid analyzer 33 measures, for example, pH, dielectric constant, and dissolved ion concentration.

[0034] As described above, the separation vessel 31 has the function of separating solids, liquids, or gases contained in the geothermal water, and also has the function of collecting or depositing scale for analysis within the separation vessel 31. Therefore, the separation vessel 31 may have a metal mesh, ceramic beads, or the like inside in order to accelerate the collection or deposition of scale within the separation vessel 31.

[0035] As shown in FIG. 1, the geothermal power generation system 1 may include a recovery tank 10 connected to the first solids outlet 315 (see FIG. 2) and the second solids outlet 319 (see FIG. 2) of the analysis device 30, and configured to store solids discharged from the first solids outlet 315 and the second solids outlet 319.

[0036] The geothermal power generation system 1 may include a fourth valve V4 provided in a flow path between the first solids discharge outlet 315 and the second solids discharge outlet 319 and the collection tank 10. Specifically, the geothermal power generation system 1 may include a fifth pipe L5 that connects the first solids discharge outlet 315 and the second solids discharge outlet 319 to an inlet of the collection tank 10, and a fourth valve V4 that is provided midway along the fifth pipe L5 and opens and closes the flow path of the fifth pipe L5. The solids discharged from the first solids discharge outlet 315 and the second solids discharge outlet 319 flow into the collection tank 10 via the fifth pipe L5 and are stored therein.

[0037] The recovery tank 10 may have a water level meter 11. This allows the amount of solids contained in the recovery tank 10 to be detected, and when the water level meter 11 reaches a specified value, the solids in the recovery tank 10 can be discarded.

[0038] The control device 40 determines at least one cleaning agent from the plurality of candidate cleaning agents based on the analysis results of the analysis device 30, and controls the supply of the cleaning agent. The plurality of candidate cleaning agents may include, for example, two or more agents selected from an acidic agent, a basic agent, a chelating agent, a hydrogen peroxide-based agent, a dispersant, and a catalase-based agent.

[0039] Acidic agents can be used to dissolve calcium-based scale. Examples of acidic agents include sulfuric acid, hydrochloric acid, acetic acid, and citric acid. Basic agents can be used to dissolve silica-based scale (amorphous silica). Examples of basic agents include sodium hydroxide, potassium hydroxide, and ammonium salts. Chelating agents can be used to mask dissolved metals in geothermal water by adjusting the pH before using other cleaning agents, thereby reducing the waste of other cleaning agents. Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), hydroxyethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), trimethanolamine, and sodium gluconate. Hydrogen peroxide-based agents can be used to dissolve soft mud. Examples of hydrogen peroxide-based agents include hydrogen peroxide solution. Dispersants can be used to disperse and remove scale adhering to the inner walls of pipes, etc. Examples of dispersants include sodium polyacrylate, various surfactants, etc. Catalase-based agents can be used to decompose hydrogen peroxide-based agents remaining in geothermal water after the use of hydrogen peroxide-based agents.

[0040] Specifically, the control device 40 determines at least one cleaning agent from among a plurality of candidate cleaning agents based on the gas analysis results of the analysis device 30, and controls the supply of the cleaning agent. For example, the control device 40 introduces a hydrogen peroxide-based chemical into the separation container 31 of the analysis device 30, and after causing the hydrogen peroxide-based chemical to react with the scale deposited in the separation container 31, determines that the main component of the scale is sludge if the concentration of oxygen detected by the gas analyzer 32 is equal to or higher than a specified value, and determines that the main component of the scale is calcium carbonate or amorphous silica if the concentration of oxygen detected by the gas analyzer 32 is equal to or lower than the specified value or zero. If it is determined that the main component of the scale is calcium carbonate or amorphous silica, an acidic agent is introduced into the separation container 31, and the acidic agent is reacted with the scale deposited in the separation container 31. If the concentration of carbon dioxide detected by the gas analyzer 32 is equal to or higher than a specified value, the main component of the scale is determined to be calcium carbonate, and if the concentration of carbon dioxide detected by the gas analyzer 32 is equal to or lower than the specified value or zero, the main component of the scale is determined to be amorphous silica or iron rust. At least one optimal cleaning agent is selected from multiple candidate cleaning agents for the main component of the scale determined as described above.

[0041] Before determining the cleaning agent, the control device 40 may introduce geothermal water into the analysis line L11 and the analysis device 30 while closing the fourth valve V4, collect the separated solids in the separation container 31, and then close the first valve V1, the second valve V2, and the third valve V3, and cause the cleaning agent addition device 50 to supply an acidic chemical or a hydrogen peroxide-based chemical to the analysis line L11, and the analysis device 30 may analyze the gas generated by the chemical reaction between the solids and the acidic chemical or the hydrogen peroxide-based chemical. Furthermore, if the control device 40 determines that the main component of the scale is ooze, it may select the hydrogen peroxide-based chemical as the first cleaning agent to be used, and a cleaning agent other than the hydrogen peroxide-based chemical as the second cleaning agent to be used. Furthermore, if the control device 40 determines that the main component of the scale is calcium carbonate, it may select the acidic chemical as the first cleaning agent to be used, and a cleaning agent other than the acidic chemical as the second cleaning agent to be used.

[0042] The cleaning agent adding device 50 may include a plurality of chemical tanks 51 a, 51 b, and 51 c that respectively store a plurality of types of candidate cleaning agents, a chemical injection pump 52 that introduces the cleaning agent into the third pipe L3, a water tank 53 that is disposed upstream of the plurality of chemical tanks 51 a, 51 b, and 51 c and stores water, and a liquid feed pump 54 that introduces water into the third pipe L3. The number of chemical tanks 51 a, 51 b, and 51 c is three in the example shown in FIG. 1 , but is not limited to this and may be four or more depending on the number of candidate cleaning agents.

[0043] The water stored in the water tank 53 is water for rinsing out the previous cleaning agent remaining in the sixth pipe L6 when the type of cleaning agent introduced into the third pipe L3 is changed, and may be, for example, one type selected from tap water, river water, and distilled water.

[0044] The cleaning agent adding device 50 may include a sixth pipe L6 connecting the discharge port of the liquid feed pump 54 and the suction port of the chemical injection pump 52, a seventh pipe L7 branching from the sixth pipe L6 and connecting to the discharge port of the chemical tank 51 a, an eighth pipe L8 branching from the sixth pipe L6 and connecting to the discharge port of the chemical tank 51 b, and a ninth pipe L9 branching from the sixth pipe L6 and connecting to the discharge port of the chemical tank 51 c. The cleaning agent adding device 50 may also include a valve V8 a provided in the seventh pipe L7 for opening and closing the flow path of the seventh pipe L7, a valve V8 b provided in the eighth pipe L8 for opening and closing the flow path of the eighth pipe L8, and a valve V8 c provided in the ninth pipe L9 for opening and closing the flow path of the ninth pipe L9.

[0045] The cleaning agent addition device 50 may include a tenth pipe L10 connected to the cleaning agent inlet of the recovery tank 10 downstream of the seventh pipe L7, the eighth pipe L8, and the ninth pipe L9, and a seventh valve V7 provided midway along the tenth pipe L10 and configured to open and close the flow path of the tenth pipe L10. The cleaning agent addition device 50 can introduce the cleaning agent into the cleaning agent inlet of the recovery tank 10 via the tenth pipe L10. Introducing the cleaning agent into the cleaning agent inlet of the recovery tank 10 can dissolve solids contained in the recovery tank 10. The cleaning agent introduced into the cleaning agent inlet of the recovery tank 10 is preferably a cleaning agent capable of dissolving solids such as ooze and colloids. Examples of the cleaning agent introduced into the cleaning agent inlet of the recovery tank 10 include a hydrogen peroxide-based agent, a basic agent, a fluoride-based agent, and a mixture of a chelating agent and a basic agent. Basic agents and fluoride-based agents can be used to dissolve silica-based colloids. The basic agent can be the same as the candidate cleaning agent described above. The fluoride-based agent can be, for example, hydrofluoric acid. A mixture of a chelating agent and a basic agent can be used to dissolve calcium-based colloids. The chelating agent can be the same as the candidate cleaning agent described above.

[0046] The recovery tank 10 may have a function for adjusting pressure. Specifically, when excessive pressure equal to or greater than a specified value is applied to the chemical injection pump 52 by the cleaning agent or water flowing through the sixth pipe L6, the control device 40 sends a signal to the seventh valve V7 to open the seventh valve V7. This allows the cleaning agent or water flowing through the sixth pipe L6 to flow into the recovery tank 10 via the tenth pipe L10, thereby reducing the pressure on the chemical injection pump 52.

[0047] From the viewpoint of improving the effect of the cleaning agent by raising the temperature of the fluid when, for example, the temperature of the geothermal water to which the cleaning agent is added drops, the geothermal power generation system 1 preferably includes a heater, a heat exchanger, or the like. The heater or the heat exchanger may be provided, for example, midway along the first pipe L1 downstream of the cleaning agent supply port 5.

[0048] The control device 40 may be capable of determining the cleaning state based on the analysis results of components contained in the fluid analyzed by the analysis device 30 after the fluid, in which the cleaning agent is added to the geothermal water flowing through the third pipe L3 by the cleaning agent addition device 50, is circulated through the cleaning agent supply line L12, the first pipe L1, the second pipe L2, and the third pipe L3. As the cleaning progresses, the inner walls of the pipes become more exposed, and iron constituting the pipes dissolves into the fluid, increasing the concentration of iron ions contained in the fluid. Therefore, the analysis results of the components contained in the fluid analyzed by the analysis device 30 may be the concentration of iron ions. For example, the control device 40 may determine that cleaning is complete when the concentration of iron ions reaches 100 ppm. The analysis results of the components contained in the fluid analyzed by the analysis device 30 may be the dielectric constant.

[0049] The geothermal power generation system 1 includes a pressure gauge 14 provided in the second cleaning agent supply line L12b and a pressure gauge 15 provided in the third pipe L3, and the control device 40 may determine that cleaning is complete when the differential pressure between the pressure detected by the pressure gauge 14 and the pressure detected by the pressure gauge 15 becomes equal to or less than a specified value. When scale adheres to the inner walls of the first pipe L1 and the second pipe L2, the cross-sectional area of ​​the flow path of the first pipe L1 and the second pipe L2 decreases. Therefore, the cleaning status can be determined based on the differential pressure between the pressure detected by the pressure gauge 14 located upstream of the first pipe L1 and the second pipe L2 and the pressure gauge 15 located downstream of the first pipe L1 and the second pipe L2.

[0050] The geothermal power generation system 1 is equipped with a flow meter 13 installed in the first pipe L1 downstream of the circulation pump 12, and the control device 40 may determine that cleaning is complete when the flow rate detected by the flow meter 13 reaches the flow rate at the start of operation (start of power generation) or a specified flow rate.

[0051] The geothermal power generation system 1 may include a ninth valve V9 provided in the second cleaning agent supply line L12b and a tenth valve V10 provided in the third pipe L3. The ninth valve V9 and the tenth valve V10 may be flow control valves.

[0052] The control device 40 is capable of controlling each of the first to seventh valves V1 to V7, valve V8a, valve V8b, valve V8c, ninth valve V9, tenth valve V10, and bypass valve V11, and can switch the flow paths in the geothermal power generation system 1 or control the flow rate of the fluid flowing through the flow paths.

[0053] As shown in FIG. 3 , the method for cleaning scale in geothermal power generation system 1 includes a step of performing normal operation (step S1), a step of introducing geothermal water into analyzer 30 after the normal operation (step S2), a step of analyzing components of scale contained in the introduced geothermal water in analyzer 30 (step S3), a step of determining at least one cleaning agent from among multiple candidate cleaning agents based on the analysis results of analyzer 30 (step S4), and a step of supplying the determined cleaning agent from cleaning agent supply port 5 to clean first pipe L1 and second pipe L2 (step S5).

[0054] In the method of cleaning scale in the geothermal power generation system 1, it is preferable to start step S3 two to three weeks after the start of step S2, in order to collect or deposit the scale required for analysis in step S3 inside the analysis device 30.

[0055] The method for cleaning scale in the geothermal power generation system 1 further includes a step (step S6) of introducing the fluid (including geothermal water and cleaning agent) after cleaning the first pipe L1 and the second pipe L2 into the analysis device 30, analyzing the components contained in the introduced fluid in the analysis device 30, and determining whether or not the cleaning is complete (cleaning status) based on the analysis results of the analysis device 30.If it is determined that the cleaning is complete (step S6: YES), a step (step S7) of performing residue and wastewater treatment is carried out, and the process returns to the step of performing normal operation (step S1).If it is determined that the cleaning is not complete (step S6: NO), the process returns to step S5 again, and steps S5 and S6 may be repeated until it is determined that the cleaning is complete.

[0056] In the residue and wastewater treatment process in the geothermal power generation system 1, before discharging the fluid after the residue removal, residues such as rock fragments and iron rust in the fluid are collected, and the residue is disposed of as industrial waste. Furthermore, it is preferable to add an acidic or basic agent to the fluid after the residue removal to adjust the pH of the fluid to the same as the pH of the geothermal water before the removal, and then discharging the fluid. If organic precipitates are formed when adjusting the pH of the fluid to the same as the pH of the geothermal water before the removal, it is preferable to add a hydrogen peroxide-based agent to decompose the precipitates before discharging the fluid. If organic solvents remain in the fluid after the residue removal and the fluid after the removal and the drainage, it is preferable to distill the fluid and then drain the fluid.

[0057] The geothermal power generation system 1 is a geothermal power generation system equipped with a binary power generation device 20 having a medium evaporator 21, and is equipped with a gas-liquid separator 3, a first pipe L1, a first valve V1, a second pipe L2, an analytical device 30, and a control device 40, and the first pipe L1 has a cleaning agent supply port 5.

[0058] With this configuration, the geothermal power generation system 1 can supply an optimum cleaning agent according to the components of the scale from the cleaning agent supply port 5 and circulate the cleaning agent through the first pipe L1 and the second pipe L2, to which scale is particularly likely to adhere, while the first valve V1 is closed to stop power generation and the geothermal power generation system 1 is maintained as a closed system without being opened or disassembled. Therefore, the geothermal power generation system 1 can remove scale regardless of the components of the scale. Furthermore, the geothermal power generation system 1 can add a cleaning agent to geothermal water that is at a relatively high temperature after power generation is stopped and circulate the water through the first pipe L1 and the second pipe L2, thereby improving the effectiveness of the cleaning agent.

[0059] The geothermal power generation system 1 includes a second valve V2, a third pipe L3, a branching section 6 that can branch into an analysis line L11 and a cleaning agent supply line L12, and a cleaning agent addition device 50.

[0060] With this configuration, the geothermal power generation system 1 can introduce the geothermal water flowing through the second pipe L2 into the analysis device 30 via the analysis line L11 while maintaining the geothermal power generation system 1 as a closed system without opening or disassembling the geothermal power generation system 1. Furthermore, by closing the first valve V1 and the second valve V2, an optimum cleaning agent depending on the components of the scale can be added to the geothermal water flowing through the third pipe L3, and the added cleaning agent can be circulated from the cleaning agent supply port 5 through the cleaning agent supply line L12 to the first pipe L1 and the second pipe L2, thereby cleaning the first pipe L1 and the second pipe L2.

[0061] Geothermal power generation system 1 includes a third valve. With this, third valve V3 can be closed and the geothermal water or cleaning agent flowing through third pipe L3 can be circulated only through analysis line L11. Therefore, before the cleaning agent is circulated through cleaning agent supply line L12, the scale components contained in the geothermal water can be analyzed by analysis device 30.

[0062] The geothermal power generation system 1 includes a fourth pipe L4. This allows geothermal water discharged from the first outlet 34 of the analyzer 30 to be supplied to the first pipe L1 from the cleaning agent supply port 5 via the cleaning agent supply line L12, and used for binary power generation.

[0063] The geothermal power generation system 1 includes a flow meter 9, and the analysis device 30 includes a separation container 31, a gas analyzer 32, and a liquid analyzer 33. As a result, the geothermal power generation system 1 can adjust the flow rate of geothermal water flowing into the analysis line L11 to be smaller than the flow rate of geothermal water flowing into the cleaning agent supply line L12, separate the geothermal water into solids, liquids, or gases in the separation container 31, and analyze the separated gases or liquids using the gas analyzer 32 or liquid analyzer 33, respectively. Thus, the analysis device 30 can determine the optimal cleaning agent depending on the components of scale contained in the geothermal water.

[0064] In geothermal power generation system 1, control device 40 determines at least one cleaning agent from among multiple candidate cleaning agent types based on the gas analysis results of analyzer 30, and controls the supply of the cleaning agent. With this configuration, the cleaning agent is introduced into separation container 31 of analyzer 30, and the cleaning agent is allowed to react with scale accumulated in separation container 31. Then, the components contained in the scale can be determined based on the analysis results of the generated gas. Thus, analyzer 30 can determine the optimal cleaning agent according to the scale components contained in the geothermal water.

[0065] In the geothermal power generation system 1, the gas analyzer 32 measures the oxygen concentration and the carbon dioxide concentration. This allows the control device 40 to introduce a hydrogen peroxide-based chemical or an acidic chemical into the separation container 31 of the analysis device 30, react the hydrogen peroxide-based chemical or the acidic chemical with the scale accumulated in the separation container 31, and then determine whether the components contained in the scale are ooze, calcium carbonate, amorphous silica, or iron rust based on the concentrations of oxygen and carbon dioxide generated. This allows the control device 40 to determine the optimal cleaning agent depending on the components of the scale contained in the geothermal water.

[0066] In the geothermal power generation system 1, the liquid analyzer 33 measures pH, dielectric constant, and dissolved ion concentration. The control device 40 then controls the liquid analyzer 33 to detect the pH of the fluid introduced into the analyzer 30 and, based on the detected pH, controls the supply of an acidic or basic chemical to the fluid to achieve a pH necessary for dissolving the scale, thereby removing the scale. When a chelating agent is used as a cleaning agent, the liquid analyzer 33 detects the pH and controls the supply of an acidic or basic chemical to the fluid to achieve an appropriate pH based on the detected pH, thereby adjusting the pH of the fluid. The control device 40 also controls the liquid analyzer 33 to detect the dielectric constant or ion concentration of the fluid introduced into the analyzer 30 and can determine the cleaning state based on the detected dielectric constant or dissolved ion concentration. As described above, the geothermal power generation system 1 is able to sufficiently remove scale regardless of the scale's composition.

[0067] In the geothermal power generation system 1, the separation vessel 31 generates a swirling flow inside to separate the solid, liquid, or gas contained in the geothermal water, thereby enabling the analysis device 30 in the geothermal power generation system 1 to efficiently analyze the scale components contained in the geothermal water.

[0068] In the geothermal power generation system 1, the separation vessel 31 has a cylindrical shape and includes a housing 311, a geothermal water inlet 312, a geothermal water outlet 313, a first chamber R1, a second chamber R2, and a third chamber R3. The first chamber R1, the second chamber R2, and the third chamber R3 are connected at the center, the first chamber R1 has a gas outlet 314, the second chamber R2 has a first solid outlet 315, and the third chamber R3 has a second solid outlet 319 and a liquid outlet 316. The geothermal water inlet 312 is positioned vertically below the geothermal water outlet 313.

[0069] With the above configuration, the separation vessel 31 generates a swirling flow inside, allowing the separation vessel 31 to efficiently separate the solid, liquid, or gas contained in the geothermal water. Therefore, the geothermal power generation system 1 can efficiently analyze the scale components contained in the geothermal water using the analysis device 30.

[0070] The geothermal power generation system 1 includes a collection tank 10. This allows the geothermal power generation system 1 to remove solids that are not required for analysis by the analysis device 30.

[0071] In geothermal power generation system 1, cleaning agent addition device 50 includes multiple chemical tanks 51a, 51b, and 51c, a chemical injection pump 52, a water tank 53, and a liquid feed pump 54. Thus, geothermal power generation system 1 can supply an optimal cleaning agent from multiple candidate cleaning agents according to the components of the scale through cleaning agent supply port 5. Thus, geothermal power generation system 1 can remove scale regardless of the components of the scale.

[0072] In geothermal power generation system 1, the multiple types of candidate cleaning agents include two or more selected from an acidic agent, a basic agent, a chelating agent, a hydrogen peroxide-based agent, a dispersant, and a catalase-based agent. This allows geothermal power generation system 1 to supply from cleaning agent supply port 5 a cleaning agent that is optimal for each of soft mud, calcium carbonate, amorphous silica, and iron rust contained in the scale.

[0073] The geothermal power generation system 1 is equipped with a fourth valve V4, and before determining the cleaning agent, the control device 40 closes the fourth valve V4 and introduces geothermal water into the analysis line L11 and the analysis device 30, collects the separated solids in the separation container 31, and then closes the first valve V1, the second valve V2, and the third valve V3, and supplies an acidic chemical or a hydrogen peroxide-based chemical to the analysis line L11 using the cleaning agent addition device 50, and the analysis device 30 analyzes the gas generated by the chemical reaction between the solids and the acidic chemical or the hydrogen peroxide-based chemical.

[0074] In the geothermal power generation system 1, the control device 40 circulates a fluid, in which a cleaning agent has been added to geothermal water flowing through the third pipe L3 by the cleaning agent addition device 50, through the cleaning agent supply line L12, the first pipe L1, the second pipe L2, and the third pipe L3, and then determines the cleaning state based on the analysis results of the components contained in the fluid analyzed by the analysis device 30. Thus, the geothermal power generation system 1 can sufficiently remove scale regardless of the scale components.

[0075] In the geothermal power generation system 1, the water stored in the water tank is one type selected from tap water, river water, and distilled water. As a result, even if the geothermal water in the first pipe L1 and the second pipe L2 is drained before cleaning, the geothermal power generation system 1 can introduce the water stored in the water tank together with the cleaning agent into the third pipe L3 and supply it to the first pipe L1 from the cleaning agent supply port 5 via the cleaning agent supply line L12.

[0076] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

[0077] This international application claims priority to Japanese Patent Application No. 2023-117849, filed on July 19, 2023, the entire contents of which are incorporated herein by reference.

[0078] REFERENCE SIGNS LIST 1 Geothermal power generation system 2 Production well 3 Gas-liquid separator 4 Reinjection well 5 Cleaning agent supply port 6 Branching section 9 Flow meter 10 Recovery tank 20 Binary power generation device 21 Media evaporator 30 Analytical device 31 Separation vessel 310 Shaft 311 Housing 312 Geothermal water inlet 313 Geothermal water outlet 314 Gas outlet 315 First solid outlet 319 Second solid outlet 32 ​​Gas analyzer 33 Liquid analyzer 34 First outlet 40 Control device 50 Cleaning agent addition device 51a, 51b, 51c Chemical tank 52 Chemical injection pump 53 Water tank 54 Liquid transfer pump L1 First pipe L2 Second pipe L3 Third pipe L4 Fourth pipe L11 Analysis line L12 Cleaning agent supply line V1 First valve V2 Second valve V3 Third valve V4 Fourth valve R1 First chamber R2 Second chamber R3 Third chamber

Claims

1. A geothermal power generation system equipped with a binary power generation unit having a media evaporator, comprising: a gas-liquid separator that separates geothermal water from geothermal fluid sprayed from a production well; a first pipe that sends the geothermal water separated by the gas-liquid separator to the media evaporator; a first valve that is provided in the first pipe and opens and closes a flow path of the first pipe; a second pipe that sends the geothermal water whose heat has been recovered by the binary power generation unit from the media evaporator to a reinjection well; an analyzer that introduces the geothermal water flowing through the second pipe and analyzes the components of scale contained in the geothermal water that has flowed in; and a control unit that determines at least one type of cleaning agent from a plurality of candidate cleaning agent types based on the analysis results of the analyzer and controls the supply of the cleaning agent, wherein the first pipe has a cleaning agent supply port downstream of the first valve through which the cleaning agent is supplied.

2. A geothermal power generation system as described in claim 1, comprising: a second valve provided in the second piping for opening and closing the flow path of the second piping; a third piping connected to the second piping upstream of the second valve; a branching section capable of branching the flow of the geothermal water or the cleaning agent flowing through the third piping into an analysis line connected to the analysis device and a cleaning agent supply line connected to the cleaning agent supply port; and a cleaning agent addition device for adding the cleaning agent to the geothermal water flowing through the third piping.

3. A geothermal power generation system as described in claim 2, further comprising a third valve provided in the cleaning agent supply line for opening and closing the flow path of the cleaning agent supply line.

4. A geothermal power generation system as described in claim 3, comprising a fourth pipe having one end connected to the first outlet of the analytical device and the other end connected to the cleaning agent supply line, for circulating the geothermal water discharged from the analytical device.

5. A geothermal power generation system as described in claim 4, further comprising a flow meter provided in the analysis line for measuring the flow rate of the geothermal water flowing into the analysis device, the analysis device having a separation container for separating the geothermal water flowing into the analysis device into solids, liquids, or gases, a gas analyzer for analyzing the gas separated from the separation container, and a liquid analyzer for analyzing the liquid separated from the separation container.

6. The geothermal power generation system described in claim 5, wherein the control device determines at least one type of cleaning agent from among the plurality of candidate cleaning agents based on the gas analysis results of the analysis device, and controls the supply of the cleaning agent.

7. The geothermal power generation system according to claim 6, wherein the gas analyzer measures the concentration of oxygen and the concentration of carbon dioxide.

8. The geothermal power generation system according to claim 7, wherein the liquid analyzer measures pH, dielectric constant, and dissolved ion concentration.

9. A geothermal power generation system according to claim 8, wherein the separation vessel generates a swirling flow therein to separate solids, liquids, or gases contained in the geothermal water.

10. The separation vessel has a cylindrical casing arranged such that its axis is at least 0° and less than 90° to the vertical direction, a geothermal water inlet provided on the side of the casing through which the geothermal water flows in, a geothermal water outlet from which the geothermal water is discharged, and a first chamber, a second chamber, and a third chamber arranged adjacent to each other in this order from the top in the vertical direction, the first chamber, the second chamber, and the third chamber are connected at the center, the first chamber is provided on the upper surface and has a gas outlet from which separated gas is discharged, the second chamber is provided on the side and has a first solid outlet from which separated solids are discharged, the third chamber is provided on the lower surface and has a second solid outlet from which separated solids are discharged, and a liquid outlet provided on the side and for discharging liquid, 10. The geothermal power generation system of claim 9, wherein the geothermal water inlet and the geothermal water outlet are provided on a side surface of the second chamber, and the geothermal water inlet is positioned vertically below the geothermal water outlet.

11. The geothermal power generation system of claim 10, further comprising a recovery tank connected to the first solids discharge outlet and the second solids discharge outlet for storing solids discharged from the first solids discharge outlet and the second solids discharge outlet.

12. The geothermal power generation system described in claim 11, wherein the cleaning agent addition device comprises a plurality of chemical tanks each containing one of the plurality of candidate cleaning agents, a chemical injection pump that introduces the cleaning agent into the third piping, a water tank arranged upstream of the plurality of chemical tanks and containing water, and a liquid delivery pump that introduces the water into the third piping.

13. The geothermal power generation system of claim 12, wherein the plurality of candidate cleaning agents include two or more selected from acidic agents, basic agents, chelating agents, hydrogen peroxide-based agents, dispersants, and catalase-based agents.

14. A geothermal power generation system as described in claim 13, further comprising a fourth valve provided in a flow path between the first solid discharge outlet and the second solid discharge outlet and the recovery tank, wherein the control device, before determining the cleaning agent, introduces the geothermal water into the analysis line and the analysis device with the fourth valve closed, and after collecting the separated solids in the separation container, closes the first valve, the second valve, and the third valve, and supplies an acidic agent or a hydrogen peroxide-based agent to the analysis line by the cleaning agent addition device, and the analysis device analyzes the gas generated by a chemical reaction between the solids and the acidic agent or the hydrogen peroxide-based agent.

15. The geothermal power generation system of claim 14, wherein the control device is capable of determining the cleaning state based on the analysis results of the components contained in the fluid analyzed by the analysis device after the fluid, in which the cleaning agent has been added to the geothermal water flowing through the third piping by the cleaning agent addition device, is circulated through the cleaning agent supply line, the first piping, the second piping, and the third piping.

16. The geothermal power generation system according to claim 15, wherein the water contained in the water tank is one type selected from tap water, river water, and distilled water.

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