Geothermal power generation system

Abstract

A geothermal power generation system according to one aspect of the present invention comprises: a gas-liquid separator; a power generation device; a retention tank; a reinjection line; a reinjection pump; a chemical injection port provided in the reinjection line between the retention tank and the reinjection pump; a first chemical addition device that injects a chemical into the chemical injection port; a branch part that is provided in the middle of the reinjection line on the downstream side of the reinjection pump and above a reinjection well in the vertical direction, and branches a flow of the geothermal water; a first liquid analyzer; a scale piece collector; a dissolving agent addition device; and a control device that, on the basis of the analysis result of the first liquid analyzer, switches between injecting of the chemical and stopping of injection by the first chemical addition device, and switches between injecting of the dissolving agent and stopping of injection by the dissolving agent addition device.

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 (geothermal water and geothermal steam) from production wells and generate electricity using the geothermal water or geothermal 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] In geothermal power generation systems, calcium and dissolved silica in geothermal water collected from production wells are concentrated by reducing pressure, and as they flow through the pipes, they are cooled and their solubility decreases. 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. Scale buildup is a problem in geothermal power generation systems because it can adhere to the inner walls of the pipes and cause blockages.

[0004] In particular, in geothermal power generation systems, scale tends to adhere to the reinjection line that returns geothermal water to the reinjection well, and it is therefore necessary to thoroughly clean the scale that has adhered to the reinjection line.For example, in the geothermal power generation system described in Patent Document 1, hydrogen peroxide solution is supplied as an oxidizing agent to the separated hot water downstream of the steam separator to prevent the buildup of silica scale in the geothermal water system.

[0005] JP 2015-90147 A

[0006] However, in a geothermal power generation system, the reduction line is usually installed over a long distance. Therefore, the cleaning agent supplied on the upstream side of the reduction line is diluted toward the downstream side. This causes a problem that scale adhered to the downstream piping cannot be sufficiently cleaned, resulting in poor cleaning.

[0007] One aspect of the present invention provides a geothermal power generation system that can sufficiently remove scale from the reduction line.

[0008] A geothermal power generation system according to one aspect of the present invention includes a gas-liquid separator that separates geothermal water and geothermal steam from geothermal fluid ejected from a production well, a power generation device that generates power using the geothermal water or the geothermal steam separated by the gas-liquid separator as a heat source, a retention tank that stores the geothermal water whose heat has been recovered by the power generation device, a reduction line that connects an outlet of the retention tank to a reduction well, a reduction pump that is provided in the reduction line and returns the geothermal water discharged from the retention tank to the reduction well, an agent injection port that is provided in the reduction line between the retention tank and the reduction pump, a first agent addition device that injects an agent into the agent injection port, and a second agent addition device that adds an agent to the reduction well. The system is equipped with a branching section that is located midway along the reinjection line, downstream of the pump and vertically above the reinjection well, and that branches the flow of the geothermal water; a first liquid analyzer connected vertically upward from the branching section; a scale fragment collector that is connected horizontally from the branching section and has a residue inlet, a dissolving agent inlet, and a residue outlet; a dissolving agent addition device that injects a dissolving agent into the dissolving agent inlet; and a control device that switches between injecting the chemical agent using the first chemical addition device and stopping injection, and switches between injecting the chemical agent using the dissolving agent addition device and stopping injection, based on the analysis results of the first liquid analyzer.

[0009] According to a geothermal power generation system according to one aspect of the present invention, scale can be sufficiently removed from the reduction line.

[0010] FIG. 1 is a schematic configuration diagram of a geothermal power generation system according to an embodiment; FIG. 2 is a time chart showing a cleaning operation in the geothermal power generation system according to an embodiment; FIG. 3 is a schematic configuration diagram showing another example of a geothermal power generation system according to an embodiment; FIG. 4 is an enlarged view of a main part of FIG. 3; FIG. 5 is an enlarged view (part 1) of a main part of FIG. 3 for explaining a cleaning operation in the other example of a geothermal power generation system according to an embodiment; FIG. 6 is an enlarged view (part 3) of a main part of FIG. 3 for explaining a cleaning operation in the other example of a geothermal power generation system according to an embodiment; FIG. 7 is an enlarged view (part 4) of a main part of FIG. 3 for explaining a cleaning operation in the other example of a geothermal power generation system according to an embodiment.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the geothermal power generation system 100 in which normal operation (power generation) is stopped and the reduction line L100 is cleaned will be described.

[0012] Figure 1 is a schematic diagram of a geothermal power generation system 100 according to one embodiment. As shown in Figure 1, the geothermal power generation system 100 includes a gas-liquid separator 3, a power generation device 101, a retention tank 102, a return line L100, a return pump 103, an agent injection port 104, a first agent addition device 130, and a control device 140. In Figure 1, arrows indicate the flow of fluid.

[0013] In the geothermal power generation system 100, geothermal fluid extracted from the production well 2 is sent to the gas-liquid separator 3. The gas-liquid separator 3 separates geothermal water and geothermal steam from the geothermal fluid ejected from the production well 2. The geothermal water and geothermal steam separated in the gas-liquid separator 3 are sent via piping to the power generation device 101, which generates power using the geothermal water or geothermal steam separated in the gas-liquid separator 3 as a heat source. The geothermal water whose heat has been recovered in the power generation device 101 is introduced into the retention tank 102 via piping.

[0014] In the example shown in Figure 1, the geothermal steam separated in the gas-liquid separator 3 is sent to a flash power generation system 101a, which generates electricity using the geothermal steam separated in the gas-liquid separator 3 as a heat source, and the geothermal water separated in the gas-liquid separator 3 is sent to a binary power generation system 101b, which generates electricity using the geothermal water separated in the gas-liquid separator 3 as a heat source.

[0015] The power generation device 101 is not particularly limited, and may include a flash power generation device 101a and a binary power generation device 101b, or may include either the flash power generation device 101a or the binary power generation device 101b.

[0016] The flash power generation system 101a includes a turbine that rotates when supplied with geothermal steam separated in the gas-liquid separator 3, a generator connected to the turbine, a condenser that condenses the geothermal steam discharged from the turbine, a cooling tower that cools the condensed water condensed in the condenser, etc. The binary power generation system 101b includes a medium evaporator that evaporates a low-boiling-point heat medium through heat exchange, a turbine that rotates when supplied with the vaporized heat medium, a generator, a medium condenser, etc.

[0017] The retention tank 102 stores the geothermal water whose heat has been recovered by the power generation device 101. The geothermal water is retained until a polymerization reaction of silica in the geothermal water progresses and the silica-based insoluble components are sufficiently coagulated and precipitated.

[0018] The reinjection line L100 is a line that connects the outlet of the retention tank 102 to the reinjection well 4.

[0019] The reduction pump 103 is provided midway along the reduction line L100 and returns the geothermal water discharged from the retention tank 102 to the reduction well 4. The geothermal water discharged from the retention tank 102 is returned to the reduction well 4 via the reduction line L100 by the reduction pump 103.

[0020] The chemical injection port 104 is provided in the reduction line L100 between the retention tank 102 and the reduction pump 103.

[0021] The first chemical addition device 130 is a device that injects a chemical into a chemical injection port, and may include multiple chemical tanks 131a, 131b, and 131c that store chemicals, and multiple chemical injection pumps 132a, 132b, and 132c that are connected to the multiple chemical tanks 131a, 131b, and 131c, respectively, and that discharge the chemicals toward the chemical injection port 104. The number of chemical tanks 131a, 131b, and 131c is three in the example shown in FIG. 1 , but is not limited to this and may be selected depending on the number of chemical types used, and may be four or more. The number of chemical injection pumps 132a, 132b, and 132c can be selected depending on the number of chemical tanks 131a, 131b, and 131c.

[0022] The multiple chemical tanks 131a, 131b, and 131c may contain a tracer reagent, a cleaning agent, and a corrosive agent that is corrosive to the metals that make up the reduction line L100, respectively. For example, the chemical tank 131a contains a tracer reagent, the chemical tank 131b contains a cleaning agent, and the chemical tank 131c contains a corrosive agent. Hereinafter, in this specification, the chemical injection pump connected to the chemical tank 131a containing the tracer reagent may be referred to as the tracer reagent injection pump 132a, the chemical injection pump connected to the chemical tank 131b containing the cleaning agent may be referred to as the cleaning agent injection pump 132b, and the chemical injection pump connected to the chemical tank 131c containing the corrosive agent may be referred to as the corrosive agent injection pump 132c.

[0023] The tracer reagent is an agent used to confirm that the cleaning agent has reached the downstream side of the reduction line L100. Examples of tracer reagents include halogens such as iodine and bromine, radioactive isotopes such as iodine-131, bromine-82, and tritium, aromatic sulfonates such as sodium benzoate, sodium toluenesulfonate, sodium xylenesulfonate, sodium benzenesulfonate, 1-naphthalenesulfonic acid, and 1,5-naphthalenedisulfonic acid, fluorescent dyes such as sodium fluorescein, rhodamine WT, and 2,6,8-naphthylaminedisulfonic acid (amino G acid), metal indicators, and benzoic acid. Among these, the tracer reagent is preferably an aromatic sulfonate.

[0024] The cleaning agent is a chemical agent for removing and cleaning scale adhering to the inside of the piping of the reduction line L100. The cleaning agent may be, for example, a chemical agent containing one or more selected from an acidic chemical agent, a basic chemical agent, a chelating agent, a hydrogen peroxide-based chemical agent, a dispersant, and a catalase-based chemical agent.

[0025] 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.

[0026] The corrosive agent is a chemical that is passed through the reduction line L100 after cleaning to elute metals constituting the piping of the reduction line L100, and the cleaning state is determined based on the concentration of the eluted metal ions. The corrosive agent may be, for example, one selected from sulfuric acid, hydrochloric acid, acetic acid, and citric acid.

[0027] The geothermal power generation system 100 may include a fourth pipe L104 connected to the chemical injection port 104 of the reduction line L100, and a fifth valve V105 provided midway along the fourth pipe L104 for opening and closing the flow path of the fourth pipe L104. The first chemical addition device 130 may also include a sixth pipe L106 branching from the fourth pipe L104 and connected to the outlet of the chemical injection pump 132a, a seventh pipe L107 branching from the fourth pipe L104 and connected to the outlet of the chemical injection pump 132b, and an eighth pipe L108 branching from the fourth pipe L104 and connected to the outlet of the chemical injection pump 132c.

[0028] Depending on the distance between the retention tank 102 and the reduction pump 103, etc., the geothermal power generation system 100 may include a temporary fifth pipe L105 that branches off from the fourth pipe L104 and extends to the inlet of the retention tank 102, as necessary. In this case, the chemical agent supplied from the first chemical addition device 130 is supplied to the reduction line L100 from the outlet of the retention tank 102 together with the geothermal water in the retention tank 102.

[0029] The geothermal power generation system 100 includes a branching section 110 that is provided midway along the reinjection line L100, downstream of the reinjection pump 103 and vertically above the reinjection well 4, and that branches the flow of geothermal water; a first liquid analyzer 111 that is connected vertically upward from the branching section 110; and a scale debris collector 113 that is connected horizontally to the branching section 110. The branching section 110 branches the flow of geothermal water in four directions and may be, for example, a four-way valve. The geothermal power generation system 100 may include a first valve V101 (reinjection valve) that is provided on the reinjection line L100 between the branching section 110 and the reinjection well 4 and that opens and closes the flow path between the branching section 110 and the reinjection well 4.

[0030] The first liquid analyzer 111 is connected to the third pipe L103 branching from the branching section 110. The first liquid analyzer 111 analyzes and detects components contained in the fluid. The first liquid analyzer 111 detects at least a tracer reagent. The first liquid analyzer 111 also measures pH, dielectric constant, or dissolved ion concentration. The first liquid analyzer 111 may be, for example, a high-performance liquid chromatograph.

[0031] The geothermal power generation system 100 may include a liquid delivery pump 112 provided midway along the third pipe L103 and discharging the fluid flowing through the reduction line L100 toward the inlet of the first liquid analyzer 111, and a fourth valve V104 provided in the third pipe L103 upstream of the liquid delivery pump 112 and opening and closing the flow path of the third pipe L103.

[0032] The scale debris collector 113 has a residue inlet 113a, a solvent inlet 113b, and a residue outlet 113c, and collects scale debris that flows through the return line L100 with a delay after cleaning of the return line L100 is completed. The geothermal power generation system 100 may include a first pipe L101 that connects the branching section 110 and the residue inlet 113a, and a second valve V102 that is provided in the first pipe L101 and opens and closes the flow path of the first pipe L101.

[0033] The geothermal power generation system 100 includes a dissolving agent addition device 150 that injects a dissolving agent into the dissolving agent inlet 113b of the scale fragment collector 113. The dissolving agent addition device 150 may include a dissolving agent tank 151 that stores the dissolving agent, and a dissolving agent injection pump 152 that is connected to the dissolving agent tank 151 and discharges the dissolving agent toward the dissolving agent inlet 113b. The dissolving agent is a chemical that dissolves the scale collected in the scale fragment collector 113, and may be, for example, one selected from a basic chemical, a fluoride-based chemical, and an acidic chemical.

[0034] The basic and acidic agents may be the same as those used in the cleaning agents described above. Examples of fluoride-based agents include hydrofluoric acid, hexafluorophosphoric acid, and ammonium fluoride.

[0035] The geothermal power generation system 100 may include a second pipe L102 that connects the solvent injection port 113b and the discharge port of the solvent injection pump 152, and a third valve V103 that is provided in the second pipe L102 and opens and closes the flow path of the second pipe L102.

[0036] Based on the analysis results of first liquid analyzer 111, control device 140 switches between injecting and stopping the drug by first drug addition device 130, and between injecting and stopping the dissolving agent by dissolving agent addition device 150. Specifically, based on the analysis results of first liquid analyzer 111, control device 140 controls multiple drug injection pumps 132a, 132b, 132c, dissolving agent injection pump 152, and first valve V101.

[0037] 2 is a time chart showing a cleaning operation in one embodiment of the geothermal power generation system 100. The control device 140 may perform the cleaning operation by causing the first chemical addition device 130 to supply the cleaning agent and simultaneously supplying the tracer reagent two or more times with an interval of five minutes or more between each supply, and then stopping the supply of the cleaning agent and closing the first valve V101 (reducing valve) after the first liquid analyzer 111 detects the tracer reagent the same number of times as the number of supplies.

[0038] As shown in FIG. 2 , at time t0, the control device 140, with the first valve V101 (reducing valve) open, sends a command to the tracer reagent injection pump 132a to discharge the tracer reagent at least twice with an interval of at least five minutes between each supply, and sends a command to the cleaning agent injection pump 132b to continuously discharge the tracer reagent. After receiving a signal from the first liquid analyzer 111 indicating that the tracer reagent has been detected the same number of times as the supply, the control device 140 sends a command to the cleaning agent injection pump 132b to stop discharging the tracer reagent at time t1, and simultaneously sends a command to the first valve V101 to close the tracer reagent injection pump 132b. By receiving the signal indicating that the tracer reagent has been detected the same number of times as the supply, the control device 140 can confirm that the cleaning agent has reached the downstream side of the reducing line L100. Time T1 is the time required for the cleaning agent to reach the downstream side of the reducing line L100.

[0039] The control device 140 opens the first valve V101 (reduction valve) two to three hours after it closes it, and then, with the first valve V101 open, causes the first chemical addition device 130 to supply a corrosive agent, and then determines the cleaning state based on the concentration of metal ions detected by the first liquid analyzer 111.

[0040] At time t2, two to three hours (time T2) after time t1, when the cleaning agent injection pump 132b stops and the first valve V101 (reduction valve) closes, the control device 140 simultaneously sends a command to the corrosive agent injection pump 132c to discharge and a command to the first valve V101 to open. Time T2 is the time required for the cleaning agent to be sufficiently brought into contact with the inner wall of the piping of the reduction line L100. Then, after time T3 has elapsed since the control device 140 received the measured value of the metal ion concentration from the first liquid analyzer 111, the control device 140 determines the cleaning state at time t3. Time T3 is the time required to confirm the cleaning state.

[0041] As cleaning progresses, the inner wall of the pipe becomes more exposed and the metal constituting the pipe dissolves into the fluid, increasing the concentration of metal ions contained in the fluid. The concentration of metal ions detected by the first liquid analyzer 111 may be the concentration of iron ions. For example, the control device 140 may determine that cleaning is complete when the concentration of iron ions reaches 100 ppm. The analysis result obtained by the first liquid analyzer 111 may be a dielectric constant.

[0042] If the concentration of metal ions detected by the first liquid analyzer 111 is less than the specified value, the control device 140 determines that cleaning is not complete and performs the cleaning operation again from time T1 to T3, repeating the cleaning operation from time T1 to T3 until the concentration of metal ions detected by the first liquid analyzer 111 reaches the specified value. Time T4 is the time for repeating the cleaning operation from time T1 to T3. The time chart showing the cleaning operation at time T4 is the same as that for times T1 to T3, and is therefore omitted from FIG. 2.

[0043] When the concentration of metal ions detected by the first liquid analyzer 111 reaches a specified value, the control device 140 determines that cleaning is complete at time t5, terminates the cleaning operation, and returns to normal operation. The time T5 from time t4 to time t5 is the final time of the time T3 for checking the cleaning state multiple times.

[0044] When the control device 140 determines that the concentration of metal ions detected by the first liquid analyzer 111 has reached a specified value and cleaning is complete, the control device 140 causes geothermal water to flow into the residue inlet 113a, causes the scale collector 113 to collect the scale, and then causes the solubilizing agent adding device 150 to inject a solubilizing agent into the solubilizing agent inlet 113b and closes the second valve V102 and the third valve V103. Specifically, when the control device 140 determines that the concentration of metal ions detected by the first liquid analyzer 111 has reached a specified value and cleaning is complete, it preferably first controls the control device 140 to open the second valve V102 and allow geothermal water to flow into the residue inlet 113a for one week or more. This allows the geothermal power generation system 100 to sufficiently collect the scale that flows through the reduction line L100 with a delay after cleaning in the scale collector 113. Next, the control device 140 injects a dissolving agent into the dissolving agent inlet 113b using the dissolving agent adding device 150, and if the dissolving agent is a basic chemical, closes the second valve V102 and the third valve V103 when the pH of the fluid in the scale debris collector 113 reaches a specified value. The pH of the fluid in the scale debris collector 113 can be detected, for example, by a pH meter (not shown) provided in the scale debris collector 113, and the control device 140 receives the measured pH value from the pH meter.

[0045] The scale fragment collector 113 is maintained at a high temperature by the sensible heat of the reinjection well 4, which improves the effect of the dissolving agent in the scale fragment collector 113 and promotes the dissolution of the scale fragments. From the viewpoint of promoting the dissolution of the scale fragments, it is preferable to position the scale fragment collector 113 so that the temperature inside the scale fragment collector 113 is maintained at 80°C or higher.

[0046] The control device 140 closes the second valve V102 and the third valve V103, leaves them as they are for 48 hours or more, and then opens the second valve V102, thereby controlling the sending of the fluid containing the dissolved scale particles in the scale particle collector 113 to the reinjection well 4 via the second pipe L102. Specifically, the control device 140 applies pressure to the inside of the scale particle collector 113 using a pressure device (not shown), thereby pushing back the geothermal water flowing in from the residue inlet 113a via the opened second valve V102, and controls the sending of the fluid containing the dissolved scale particles in the scale particle collector 113 to the reinjection well 4 via the second pipe L102.

[0047] The control device 140 then controls the discharge of scale particles, rock fragments, iron rust, etc. remaining in the scale particle collector 113 to the outside through the residue discharge port 113c.

[0048] The control device 140 may further control the reduction pump 103, the liquid feed pump 112, the fourth valve V104, the fifth valve V105, and the sixth valve V106.

[0049] Next, another example of the geothermal power generation system 100 will be described. This other example of the geothermal power generation system 100 is an embodiment of the geothermal power generation system 100 in which the reduction line L100 is cleaned during normal operation (during power generation). Figure 3 is a schematic configuration diagram showing another example of the geothermal power generation system 100 according to one embodiment, and Figure 4 is an enlarged view of a main part of Figure 3. In Figures 3 and 4, arrows indicate the flow of fluid.

[0050] 1 and 2 , the geothermal power generation system 100 may include, as shown in Figures 3 and 4 , a first bypass pipe L121 branching off from the return line L100 and connected to the return line L100 downstream of the return pump 103, and a second bypass pipe L122 branching off from the return line L100 and connected to the return line L100 downstream of the first bypass pipe L121. The geothermal power generation system 100 may also include a first switching valve V121 provided in the return line L100 and capable of switching the flow path of the return line L100 to the first bypass pipe L121, and a second switching valve V122 provided in the return line L100 and capable of switching the flow path of the return line L100 to the second bypass pipe L122.

[0051] Furthermore, as shown in Figure 4, the geothermal power generation system 100 may be equipped with a chemical adjustment section 115 provided in the first bypass piping L121, a first gate valve V123 provided in the first bypass piping L121 upstream of the chemical adjustment section 115, a second gate valve V124 provided in the first bypass piping L121 downstream of the chemical adjustment section 115, a second chemical addition device 170, and an air introduction device 116.

[0052] The drug adjustment section 115 is the first bypass pipe L121 between the first gate valve V123 and the second gate valve V124, and is a part for introducing air into the drug in the drug adjustment section 115 and adjusting the drug to be supplied to the return line L100.

[0053] The second chemical addition device 170 injects a chemical into the chemical preparation unit 115. The second chemical addition device 170 may include a chemical tank 171 that stores the chemical, and a chemical injection pump 172 that is connected to the chemical tank 171 and ejects the chemical toward the chemical preparation unit 115. While the number of chemical tanks 171 is one in the example shown in FIG. 4 , this is not limited to one, and may be selected according to the number of chemical types used, and may be multiple. The number of chemical injection pumps 172 may be selected according to the number of chemical tanks 171.

[0054] The chemical stored in the chemical tank 171 may be a cleaning agent, or a cleaning agent and a corrosive agent that is corrosive to the metal that constitutes the reduction line L100. There may be multiple chemical tanks 171, and when the chemical is a cleaning agent and a corrosive agent, the cleaning agent and the corrosive agent are stored in separate chemical tanks 171.

[0055] The cleaning agent is an agent for removing and cleaning scale adhering to the inside of the piping of the reduction line L100. As the cleaning agent, the same cleaning agent as in the embodiment shown in FIG. 1 can be used.

[0056] The corrosive agent is a chemical that is passed through the reduction line L100 after cleaning to dissolve metals that constitute the piping of the reduction line L100, and the cleaning state is determined based on the concentration of the dissolved metal ions. As the corrosive agent, the same corrosive agent as in the embodiment shown in FIG. 1 can be used.

[0057] The air introduction device 116 supplies air to the chemical in the chemical preparation unit 115. Examples of the air introduction device 116 include an air compressor and a blower. The geothermal power generation system 100 may include an air filter 117 provided upstream of the air introduction device 116 and a drainage pump 118 that drains the geothermal water in the chemical preparation unit 115.

[0058] The geothermal power generation system 100 may include a ninth pipe L123 connected to the chemical preparation unit 115, a tenth pipe L124 branching from the ninth pipe L123 and connected to the first bypass pipe L121 downstream of the second gate valve V124, an eleventh pipe L125 branching from the ninth pipe L123 and connected to the outlet of the air introduction device 116, and a twelfth pipe L126 branching from the eleventh pipe L125 and connected to the outlet of the chemical injection pump 172. The drainage pump 118 is provided in the tenth pipe L124.

[0059] The ninth pipe L123 extends vertically downward from the chemical preparation unit 115. The ninth pipe L123 sends the cleaning agent and air to the chemical preparation unit 115 and also sends the geothermal water discharged from the chemical preparation unit 115 to the tenth pipe L124. The geothermal power generation system 100 may include a thirteenth pipe L127 connected to the chemical preparation unit 115 and extending vertically upward from the chemical preparation unit 115. The thirteenth pipe L127 discharges air from the chemical preparation unit 115 to the outside and introduces air into the chemical preparation unit 115. The geothermal power generation system 100 may include a fifteenth valve V130 provided midway along the thirteenth pipe L127 and configured to open and close the flow path of the thirteenth pipe L127.

[0060] The geothermal power generation system 100 may include a seventh valve V125 provided midway along the ninth pipe L123 and opening and closing the flow path of the ninth pipe L123, an eighth valve V126 provided downstream of the drainage pump 118 in the tenth pipe L124 and opening and closing the flow path of the tenth pipe L124, a ninth valve V127 provided midway along the eleventh pipe L125 and opening and closing the flow path in the eleventh pipe L125 downstream of the branch point to the twelfth pipe L126, a tenth valve V129 that opens and closes the flow path upstream of the branch point to the twelfth pipe L126, and an eleventh valve V128 provided downstream of the chemical injection pump 172 in the twelfth pipe L126 and opening and closing the flow path of the twelfth pipe L126.

[0061] The geothermal power generation system 100 may include an air separation section 120 provided in the second bypass pipe L122, a third gate valve V131 provided in the second bypass pipe L122 upstream of the air separation section 120, a fourth gate valve V132 provided in the second bypass pipe L122 downstream of the air separation section 120, and a second liquid analyzer 121 connected to the air separation section 120.

[0062] The air separation unit 120 is a part for separating (degassing) air from the fluid (geothermal water and chemicals) in the air separation unit 120. The second liquid analyzer 121 measures, for example, pH, dielectric constant, or dissolved ion concentration.

[0063] The geothermal power generation system 100 may include a fourteenth pipe L128 connected to the air separation unit 120 and extending vertically upward, and a fifteenth pipe L129 connected to the air separation unit 120 and extending vertically downward. The fourteenth pipe L128 discharges air separated in the air separation unit 120 to the outside. The geothermal power generation system 100 may include an air vent valve V133 provided midway along the fourteenth pipe L128. The air vent valve V133 automatically discharges air that has accumulated in the air separation unit 120. The fifteenth pipe L129 connects the air separation unit 120 to the second liquid analyzer 121 and sends the fluid in the air separation unit 120 to the second liquid analyzer 121. The geothermal power generation system 100 may include a liquid delivery pump 122 that is provided midway along the 15th pipe L129 and discharges the fluid flowing through the 15th pipe L129 toward the inlet of the second liquid analyzer 121, and a 12th valve V134 that is provided on the 15th pipe L129 upstream of the liquid delivery pump 122 and opens and closes the flow path of the 15th pipe L129.

[0064] Based on the analysis results of the second liquid analyzer 121, the control device 140 may switch between injecting and stopping the drug using the second drug addition device 170, and between introducing and stopping the air using the air introduction device 116, and may also control the first switching valve V121, the second switching valve V122, and the first to fourth check valves V123, V124, V131, and V132.

[0065] Next, a detailed description will be given of the cleaning operation in another example of the geothermal power generation system 100. Figures 5A to 5D are enlarged views of the main parts of Figure 3 for explaining the cleaning operation in another example of the geothermal power generation system 100 according to one embodiment. In Figures 5A to 5D, open valves are shown in white, closed valves are shown in black, and arrows indicate the flow of fluid.

[0066] The control device 140 may repeat normal operation, a drainage operation to discharge the geothermal water in the chemical preparation unit 115 after the normal operation, a chemical injection operation to inject a chemical into the chemical preparation unit 115 from which the geothermal water has been discharged, an air introduction operation to introduce air into the chemical injected into the chemical preparation unit 115, and a cleaning operation to switch the flow path of the reduction line L100 to the first bypass pipe L121 and the second bypass pipe L122 and perform cleaning.

[0067] 5A, in normal operation, the control device 140 opens the first selector valve V121 and the second selector valve V122 and closes the first to fourth gate valves V123, V124, V131, and V132. In normal operation, the geothermal water flows through the reduction line L100 but does not flow through the first bypass pipe L121 or the second bypass pipe L122.

[0068] 5B , in a drainage operation to drain the geothermal water from the chemical preparation unit 115, the control device 140 opens the seventh valve V125 and the eighth valve V126 and operates the drain pump 118 to drain the geothermal water accumulated in the chemical preparation unit 115 and send it via the ninth pipe L123 and the tenth pipe L124 to the first bypass pipe L121 downstream of the second gate valve V124. At this time, the control device 140 opens the fifteenth valve V130, thereby draining the geothermal water accumulated in the chemical preparation unit 115 and introducing air into the chemical preparation unit 115 via the thirteenth pipe L127.

[0069] Next, as shown in Figure 5C, in the drug injection operation for injecting a drug into the drug preparation unit 115, the control device 140 closes the eighth valve V126, opens the seventh valve V125, as well as the ninth valve V127 and the eleventh valve V128, operates the drug injection pump 172, and starts the drug injection operation by the second drug addition device 170. At this time, the drug is injected into the drug preparation unit 115, and air inside the drug preparation unit 115 is discharged to the outside via the thirteenth pipe L127.

[0070] 5D, in the air introduction operation for introducing air into the medicine, the control device 140 closes the eleventh valve V128 and the fifteenth valve V130 and opens the seventh valve V125, the ninth valve V127, and the tenth valve V129. The control device 140 also stops the medicine injection pump 172 to stop the medicine injection by the second medicine addition device 170, and activates the air introduction device 116 to supply air to the medicine in the medicine preparation unit 115 via the ninth pipe L123 and the eleventh pipe L125.

[0071] Then, in the line switching operation in which the flow path of the reduction line L100 is switched to the first bypass pipe L121 and the second bypass pipe L122 and cleaning is started, the control device 140 opens the first to fourth gate valves V123, V124, V131, and V132, switches the flow path of the reduction line L100 to the first bypass pipe L121 and the second bypass pipe L122, and controls the flow of the drug containing air in the drug preparation unit 115 to the reduction line L100 and the second bypass pipe L122.

[0072] The air introduced into the chemical in the chemical preparation unit 115 is discharged to the outside via the air vent valve V133 and the fourteenth pipe L128 in the air separation unit 120. That is, the geothermal power generation system 100 separates the air from the fluid (fluid containing geothermal water, chemical, and air) in the air separation unit 120, and then circulates the fluid from which the air has been separated through the return line L100 downstream of the second bypass pipe L122.

[0073] After the line switching operation, the control device 140 repeats the normal operation, the drainage operation, the chemical injection operation, the air introduction operation, and the line switching operation again after a predetermined time has elapsed.

[0074] After performing the cleaning operation, the control device 140 may close the first selector valve V121 and the second selector valve V122 and open the first to fourth gate valves V123, V124, V131, and V132. After stopping the injection of chemicals by the second chemical addition device 170 and supplying a corrosive agent by the second chemical addition device 170, the control device 140 may determine the cleaning state based on the concentration of metal ions detected by the second liquid analyzer 121. The concentration of metal ions detected by the second liquid analyzer 121 may be the concentration of iron ions. For example, the control device 140 may determine that cleaning is complete when the concentration of iron ions reaches 100 ppm. The analysis result by the first liquid analyzer 111 may be a dielectric constant.

[0075] If the concentration of metal ions detected by the second liquid analyzer 121 is less than a specified value, the control device 140 determines that cleaning is not complete and may repeat normal operation, drainage operation, chemical injection operation, air introduction operation, and cleaning operation again.

[0076] When the concentration of metal ions detected by the second liquid analyzer 121 reaches a specified value, the control device 140 determines that cleaning is complete, performs normal operation, and terminates the subsequent chemical injection operation, air introduction operation, and cleaning operation.

[0077] The geothermal power generation system 100 includes a gas-liquid separator 3, a power generation device 101, a retention tank 102, a return line L100, a return pump 103, an agent injection port 104 provided in the return line L100 between the retention tank 102 and the return pump 103, and a first agent addition device 130. The geothermal power generation system 100 also includes a branching section 110, a first liquid analyzer 111, a scale fragment collector 113 having a residue inlet 113a, a dissolving agent injection port 113b, and a residue outlet 113c, a dissolving agent addition device 150, and a control device 140 that switches between starting and stopping the agent injection operation by the first agent addition device 130 and switching between starting and stopping the dissolving agent injection operation by the dissolving agent addition device 150 based on the analysis results of the first liquid analyzer 111.

[0078] With this configuration, the control device 140 confirms the arrival of the chemical agent based on the analysis results of the first liquid analyzer 111 provided downstream of the return line L100 and switches between injecting and stopping the chemical agent using the first chemical agent adding device 130. Therefore, the geothermal power generation system 100 can distribute the chemical agent throughout the entire return line L100 from the upstream side to the downstream side and clean the return line L100 without opening or disassembling the geothermal power generation system 100. Furthermore, even if scale particles flow through the return line L100 after cleaning the geothermal power generation system 100, the scale particles are collected using the scale particle collector 113, and the control device 140 switches between injecting and stopping the dissolving agent using the dissolving agent adding device 150. Therefore, the geothermal power generation system 100 can dissolve and remove scale particles flowing through the return line L100 after cleaning without opening or disassembling the geothermal power generation system 100. As a result, the geothermal power generation system 100 can sufficiently remove scale from the reduction line L100.

[0079] Specifically, geothermal power generation system 100 includes first valve V101, first chemical addition device 130 includes multiple chemical tanks 131a, 131b, and 131c and multiple chemical injection pumps 132a, 132b, and 132c, and dissolving agent addition device 150 includes dissolving agent tank 151 and dissolving agent injection pump 152. Furthermore, control device 140 controls multiple chemical injection pumps 132a, 132b, and 132c, dissolving agent injection pump 152, and first valve V101 based on the analysis results of first liquid analyzer 111.

[0080] With this configuration, the control device 140 selects a chemical appropriate for the purpose from among multiple chemicals based on the analysis results of the first liquid analyzer 111 and controls the chemical injection pump that discharges the selected chemical, thereby allowing the geothermal power generation system 100 to supply the chemical appropriate for the purpose to the return line L100. After the control device 140 distributes the chemical throughout the return line L100, the control device 140 closes the first valve V101, allowing the geothermal power generation system 100 to thoroughly contact the chemical with the inner wall of the return line L100 piping and enhance the cleaning effect. Furthermore, the control device 140 controls the solvent injection pump 152 based on the analysis results of the first liquid analyzer 111, allowing the geothermal power generation system 100 to thoroughly dissolve and remove scale particles circulating through the return line L100 after cleaning. As a result, the geothermal power generation system 100 can more thoroughly remove scale from the return line L100.

[0081] In the geothermal power generation system 100, multiple chemical tanks 131a, 131b, and 131c contain a tracer reagent, a cleaning agent, and a corrosive agent that is corrosive to the metals that make up the return line L100. By simultaneously supplying the tracer reagent and the cleaning agent to the return line L100, the geothermal power generation system 100 can confirm the arrival of the cleaning agent using the first liquid analyzer 111, and can spread the cleaning agent throughout the return line L100 from the upstream to downstream sides, thereby cleaning the return line L100. Furthermore, by supplying the corrosive agent to the return line L100, the geothermal power generation system 100 can dissolve metals that make up the piping of the return line L100 and determine the cleaning state based on the concentration of the eluted metal ions. Therefore, the geothermal power generation system 100 can more thoroughly remove scale from the return line L100.

[0082] In the geothermal power generation system 100, the tracer reagent is preferably an aromatic sulfonate. In the geothermal power generation system 100, by supplying the aromatic sulfonate as the tracer reagent to the reduction line L100 simultaneously with the cleaning agent, the tracer reagent can be easily detected by the first liquid analyzer 111, and the arrival of the cleaning agent can be easily confirmed.

[0083] In the geothermal power generation system 100, the cleaning agent includes one 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 the geothermal power generation system 100 to supply to the reduction line L100 the cleaning agent that is optimal for each of the soft mud, calcium carbonate, amorphous silica, iron rust, and the like contained in the scale.

[0084] In the geothermal power generation system 100, the corrosive agent is one selected from sulfuric acid, hydrochloric acid, acetic acid, and citric acid. The geothermal power generation system 100 supplies one selected from sulfuric acid, hydrochloric acid, acetic acid, and citric acid as the corrosive agent to the reduction line L100, thereby eluting iron constituting the piping of the reduction line L100, and the cleaning state can be determined based on the concentration of the eluted iron ions.

[0085] In the geothermal power generation system 100, the dissolving agent is one selected from a basic agent, a fluoride-based agent, and an acidic agent, thereby enabling the geothermal power generation system 100 to supply the scale fragment collector 113 with the most suitable dissolving agent for each of calcium carbonate, amorphous silica, and the like contained in the scale.

[0086] In the geothermal power generation system 100, the control device 140 causes the first chemical addition device 130 to supply the cleaning agent and at the same time supply the tracer reagent two or more times with an interval of five minutes or more between each supply, and after the first liquid analyzer 111 detects the tracer reagent the same number of times as the number of supplies, stops the supply of the cleaning agent and closes the first valve V101, thereby performing the cleaning operation.

[0087] As a result, the control device 140 confirms the arrival of the cleaning agent using the first liquid analyzer 111, and after the cleaning agent has spread throughout the entire return line L100, closes the first valve V101, allowing the geothermal power generation system 100 to bring the cleaning agent into sufficient contact with the inner wall of the piping of the return line L100, thereby improving the cleaning effect. Thus, the geothermal power generation system 100 can more sufficiently remove scale from the return line L100.

[0088] In the geothermal power generation system 100, the control device 140 opens the first valve V101 two to three hours after the first valve V101 is closed, causes the first chemical agent addition device 130 to supply a corrosive agent, and then determines the cleaning state based on the concentration of metal ions detected by the first liquid analyzer 111. This allows the geothermal power generation system 100 to clean the return line L100 according to the cleaning state, and more sufficiently removes scale from the return line L100.

[0089] In the geothermal power generation system 100, if the concentration of metal ions detected by the first liquid analyzer 111 is less than a specified value, the control device 140 determines that cleaning is not complete and performs the cleaning operation again, repeating the cleaning operation until the concentration of metal ions detected by the first liquid analyzer 111 reaches the specified value. This allows the geothermal power generation system 100 to prevent poor cleaning of the return line L100 and more thoroughly remove scale from the return line L100.

[0090] The geothermal power generation system 100 includes a second valve V102 and a third valve V103. When the control device 140 determines that the metal ion concentration detected by the first liquid analyzer 111 has reached a specified value and cleaning is complete, the control device 140 causes geothermal water to flow into the residue inlet 113a, causes the scale collector 113 to collect scale, and then causes the dissolving agent adding device 150 to inject a dissolving agent into the dissolving agent inlet 113b, and closes the second valve V102 and the third valve V103. As a result, when scale flows through the return line L100 after cleaning of the return line L100 is completed, the geothermal power generation system 100 can collect, dissolve, and remove the scale using the scale collector 113. Therefore, the geothermal power generation system 100 can sufficiently remove scale from the return line L100.

[0091] In the geothermal power generation system 100, the control device 140 closes the second valve V102 and the third valve V103, leaves them open for 48 hours or more, and then opens the second valve V102, thereby controlling the sending of a fluid containing dissolved scale particles in the scale particle collector to the reinjection well 4 via the second pipe L102. The control device 140 immerses the scale particles collected in the scale particle collector 113 in a dissolving agent in an environment maintained at a high temperature by receiving sensible heat from the reinjection well 4, thereby allowing the geothermal power generation system 100 to thoroughly dissolve and remove the scale particles. Thus, the geothermal power generation system 100 can more thoroughly remove scale from the reinjection line L100.

[0092] In the geothermal power generation system 100, the control device 140 controls the discharge of scale particles remaining in the scale particle collector 113 to the outside through the residue discharge port 113c, thereby enabling the control device 140 to remove the sparingly soluble scale particles that could not be dissolved by the solvent in the scale particle collector 113.

[0093] The geothermal power generation system 100 includes a first bypass pipe L121, a second bypass pipe L122, a first switching valve V121, a second switching valve V122, an agent preparation unit 115, a first gate valve V123, a second gate valve V124, a second agent addition device 170, an air introduction device 116, an air separation unit 120, a third gate valve V131, a fourth gate valve V132, and a second liquid analyzer 121. The control device 140 switches between injecting and stopping injection of agent by the second agent addition device 170 and between introducing and stopping air introduction by the air introduction device 116 based on the analysis results of the second liquid analyzer 121, and controls the first switching valve V121, the second switching valve V122, and the first to fourth gate valves V123, V124, V131, and V132.

[0094] This configuration allows the geothermal power generation system 100 to clean the return line L100 even during normal operation (power generation). The control device 140 controls the air introduction device 116 to introduce air into the chemical agent supplied by the second chemical agent addition device 170. The control device 140 then controls the first selector valve V121, the second selector valve V122, and the first through fourth gate valves V123, V124, V131, and V132 to switch the flow path of the return line L100 to the first bypass pipe L121 and the second bypass pipe L122, allowing the chemical agent with the introduced air to flow through the return line L100. This reduces the contact area between the chemical agent and the geothermal water and prevents dilution of the chemical agent while it flows through the return line L100. Furthermore, the control device 140 controls the second chemical agent addition device 170 to supply a corrosive agent, allowing the control device 140 to determine the cleaning state based on the concentration of metal ions detected by the second liquid analyzer 121. Therefore, the geothermal power generation system 100 can continue cleaning until the return line L100 is sufficiently cleaned. As described above, the geothermal power generation system 100 can sufficiently remove scale from the return line L100 even during normal operation.

[0095] In the geothermal power generation system 100, the control device 140 repeats the following operations: normal operation; after the normal operation, a drainage operation in which the geothermal water in the chemical preparation unit 115 is drained; a chemical injection operation in which a chemical is injected into the chemical preparation unit 115 from which the geothermal water has been drained; an air introduction operation in which air is introduced into the chemical injected into the chemical preparation unit 115; and a line switching operation in which the flow path of the return line L100 is switched to the first bypass pipe L121 and the second bypass pipe L122 to start cleaning. As a result, the chemical containing air is repeatedly supplied into the geothermal water in the return line L100, and the air surrounding the chemical acts as a barrier, making it difficult for the chemical to diffuse into the geothermal water. Therefore, the geothermal power generation system 100 can further suppress dilution of the chemical while it flows through the return line L100.

[0096] After separating air from the fluid in the air separation unit 120, the geothermal power generation system 100 circulates the fluid from which the air has been separated through the reinjection line L100 downstream of the second bypass pipe L122. This allows the geothermal power generation system 100 to maintain the permeability of the geothermal water that is returned to the reinjection well 4 via the reinjection line L100 downstream of the second bypass pipe L122.

[0097] 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.

[0098] This international application claims priority to Japanese Patent Application No. 2023-117850, filed on July 19, 2023, the entire contents of which are incorporated herein by reference.

[0099] 100 Geothermal power generation system 2 Production well 3 Gas-liquid separator 4 Reinjection well 101 Power generation device 102 Retention tank 103 Reinjection pump 104 Chemical injection port 110 Branching section 111 First liquid analyzer 113 Scale fragment collector 113a Residue inlet 113b Dissolving agent injection port 113c Residue discharge port 115 Chemical preparation section 116 Air introduction device 120 Air separation section 121 Second liquid analyzer 130 First chemical addition device 131a, 131b, 131c Chemical tank 132a, 132b, 132c Chemical injection pump 140 Control device 150 Dissolving agent addition device 151 Dissolving agent tank 152 Dissolving agent injection pump 170 Second chemical addition device L100 Reinjection line L101 First pipe L102 Second pipe V101 First valve V102 Second valve V103 Third valve L121 First bypass pipe L122 Second bypass pipe V121 First change-over valve V122 Second change-over valve V123 First gate valve V124 Second gate valve V131 Third gate valve V132 Fourth gate valve

Claims

1. A gas-liquid separator which separates geothermal water and geothermal steam from geothermal fluid spouted from a production well; a power generation device which generates power using the geothermal water or the geothermal steam separated by the gas-liquid separator as a heat source; a retention tank which stores the geothermal water whose heat has been recovered by the power generation device; a reduction line which connects the outlet of the retention tank to a reduction well; a reduction pump which is provided midway along the reduction line and which returns the geothermal water discharged from the retention tank to the reduction well; a chemical injection port which is provided on the reduction line between the retention tank and the reduction pump; a first chemical addition device which injects chemicals into the chemical injection port; a branching section which is provided midway along the reduction line downstream of the reduction pump and vertically above the reduction well and which branches the flow of the geothermal water; and a first liquid analyzer which is connected vertically upward from the branching section. A geothermal power generation system comprising: a scale fragment collector connected horizontally to the branching section and having a residue inlet, a dissolving agent inlet, and a residue discharge outlet; a dissolving agent addition device that injects a dissolving agent into the dissolving agent inlet; and a control device that switches between injecting the agent by the first chemical agent addition device and stopping injection, and switches between injecting the agent by the dissolving agent addition device and stopping injection, based on the analysis results of the first liquid analyzer.

2. A geothermal power generation system as described in claim 1, comprising: a first valve provided in the reinjection line between the branching portion and the reinjection well, opening and closing the flow path between the branching portion and the reinjection well; the first chemical addition device having a plurality of chemical tanks for storing the chemical, and a plurality of chemical injection pumps connected to each of the plurality of chemical tanks for discharging the chemical toward the chemical injection port; the dissolving agent addition device having a dissolving agent tank for storing the dissolving agent, and a dissolving agent injection pump connected to the dissolving agent tank for discharging the dissolving agent toward the dissolving agent injection port; and the control device controlling the plurality of chemical injection pumps, the dissolving agent injection pump, and the first valve based on the analysis results of the first liquid analyzer.

3. A geothermal power generation system as described in claim 2, wherein each of the multiple chemical tanks contains a tracer reagent, a cleaning agent, and a corrosive agent that is corrosive to the metals that make up the reduction line.

4. The geothermal power generation system according to claim 3, wherein the tracer reagent is an aromatic sulfonate.

5. The geothermal power generation system according to claim 3, wherein the cleaning agent includes one or more selected from an acidic agent, a basic agent, a chelating agent, a hydrogen peroxide-based agent, a dispersing agent, and a catalase-based agent.

6. The geothermal power generation system according to claim 3, wherein the corrosive agent is one selected from the group consisting of sulfuric acid, hydrochloric acid, acetic acid, and citric acid.

7. The geothermal power generation system according to claim 1, wherein the dissolving agent is one selected from the group consisting of a basic agent, a fluoride-based agent, and an acidic agent.

8. The geothermal power generation system of claim 3, wherein the control device causes the first chemical addition device to supply the cleaning agent and at the same time supplies the tracer reagent two or more times with an interval of five minutes or more between each supply, and after the first liquid analyzer detects the tracer reagent the same number of times as the number of supplies, stops the supply of the cleaning agent and closes the first valve, thereby performing a cleaning operation.

9. The geothermal power generation system of claim 8, wherein the control device opens the first valve 2 to 3 hours after the first valve is closed, causes the first chemical addition device to supply the corrosive agent, and then determines the cleaning condition based on the concentration of metal ions detected by the first liquid analyzer.

10. A geothermal power generation system as described in claim 9, wherein the control device determines that cleaning is not complete when the concentration of the metal ions detected by the first liquid analyzer is less than a specified value, and performs the cleaning operation again, repeating the cleaning operation until the concentration of the metal ions detected by the first liquid analyzer reaches a specified value.

11. A geothermal power generation system as described in claim 10, comprising: a second valve provided in a first pipe connecting the branching portion and the residue inlet, opening and closing the flow path of the first pipe; and a third valve provided in a second pipe connecting the dissolving agent inlet and the discharge outlet of the dissolving agent injection pump, opening and closing the flow path of the second pipe, wherein when the concentration of the metal ions detected by the first liquid analyzer reaches a specified value and it is determined that cleaning is complete, the control device causes the geothermal water to flow into the residue inlet, causes the scale pieces to be collected in the scale piece collector, and then causes the dissolving agent to be injected into the dissolving agent inlet by the dissolving agent addition device and closes the second valve and the third valve.

12. The geothermal power generation system described in claim 11, wherein the control device closes the second valve and the third valve, leaves them as they are for 48 hours or more, and then opens the second valve, thereby controlling the sending of fluid containing dissolved scale particles in the scale particle collector to the injection well via the second piping.

13. A geothermal power generation system as described in claim 12, wherein the control device controls the discharge of scale particles remaining in the scale particle collector to the outside through the residue discharge outlet.

14. A first bypass pipe branching off from the reduction line downstream of the reduction pump and connected to the reduction line; a second bypass pipe branching off from the reduction line downstream of the first bypass pipe and connected to the reduction line; a first changeover valve provided in the reduction line and capable of switching the flow path of the reduction line to the first bypass pipe; a second changeover valve provided in the reduction line and capable of switching the flow path of the reduction line to the second bypass pipe; a drug adjustment unit provided in the first bypass pipe, a first gate valve provided in the first bypass pipe upstream of the drug adjustment unit, and a second gate valve provided in the first bypass pipe downstream of the drug adjustment unit; a second drug addition device that injects a drug into the drug adjustment unit; and an air introduction device that supplies air to the drug in the drug adjustment unit. The geothermal power generation system of claim 1, comprising: an air separation section provided in the second bypass piping, a third gate valve provided in the second bypass piping upstream of the air separation section, and a fourth gate valve provided in the second bypass piping downstream of the air separation section; and a second liquid analyzer connected to the air separation section, wherein the control device switches between the injection operation and the stop of injection of the chemical by the second chemical addition device, and switches between the introduction operation and the stop of introduction of air by the air introduction device, based on the analysis results of the second liquid analyzer, and controls the first switching valve, the second switching valve, and the first to fourth gate valves.

15. The geothermal power generation system of claim 14, wherein the control device repeats normal operation, and after the normal operation, a drainage operation for discharging the geothermal water in the chemical preparation section, a chemical injection operation for injecting the chemical into the chemical preparation section from which the geothermal water has been discharged, an air introduction operation for introducing air into the chemical injected into the chemical preparation section, and a line switching operation for switching the flow path of the reduction line to the first bypass piping and the second bypass piping to begin cleaning.

16. A geothermal power generation system as described in claim 15, wherein after air is separated from the fluid in the air separation section, the fluid from which the air has been separated is circulated through the reduction line downstream of the second bypass piping.

Images