Flow passage maintenance system and flow passage maintenance method

Abstract

[Problem] To inhibit scale formation on an inner wall of a flow passage, and / or corrosion of the inner wall of the flow passage. [Solution] A scale-inhibiting system 1 comprises: a piping 11 in which a hydrophilic liquid L1 flows; a storage unit 12 which is provided at an outflow port of the piping 11, and stores the hydrophilic liquid L1 and a hydrophobic liquid L2 having specific gravity different from that of the hydrophilic liquid L1; a circulation piping 13 having one end connected to a portion of the storage unit 12 where the hydrophobic liquid L2 is stored, and another end connected to the piping 11; and a pump 14 which is provided in the circulation piping 13, and generates multiphase flow of the hydrophilic liquid L1 and the hydrophobic liquid L2 in the piping 11 by injecting the hydrophobic liquid L2 stored in the storage unit 12 into the piping 11.

Description

Flow path maintenance system and flow path maintenance method

[0001] The present invention relates to a flow path maintenance system and a flow path maintenance method, and more particularly to a system and a method for suppressing the formation of scale that adheres to the inner wall of a flow path through which a hydrophilic liquid flows and / or corrosion of the inner wall of the flow path.

[0002] It is known that scale adheres to the inner walls of fluid flow passages. For example, scale adheres to the inner walls of pipes that carry hot spring water to a designated location or pipes that carry cooling water to a power plant. It is also known that scale adheres to the inner walls of flow passages in heat exchangers.

[0003] Scale is formed when substances contained in the fluid deposit on the inner walls of the flow path or when they precipitate from the fluid and adhere to the inner walls of the flow path. For example, the scale that adheres to the inner walls of a pipe carrying hot spring water is metal oxide formed when calcium and silica components in the fluid precipitate on the inner walls of the pipe.

[0004] Patent Document 1 describes a method for removing scale adhering to the inner surface of a heat transfer tube by adding particles to the liquid flowing inside the heat transfer tube and making the flow inside the tube a solid-gas-liquid three-phase flow of the particles, gas, and cooling water.

[0005] Patent Document 2 describes a method of suppressing scale buildup inside a pipe by mixing fine air bubbles into a liquid flowing inside the pipe and utilizing the fact that the negatively charged fine air bubbles attract positively charged calcium ions and the like.

[0006] Patent Document 3 describes a method for preventing scale buildup on pipes by adding water to areas where scale buildup is expected and diluting the filtrate obtained by washing incineration ash.

[0007] Patent Document 4 describes that scale adhesion to the inside of secondary heat exchange sections such as the piping and evaporator of a binary power generation system is prevented by supplying a heat medium that has exchanged heat with heat source water to the secondary heat exchange section so that the heat source water does not pass through the secondary heat exchange section of the binary power generation system.

[0008] Patent Document 5 describes a cleaning method capable of cleaning the inner wall of a flow pipe. In this method, a liquid-liquid interface is moved while being in contact with the inner wall, thereby peeling off the material to be removed from the inner wall.

[0009] Japanese Patent Laid-Open No. 5-180594 Japanese Patent Laid-Open No. 2012-81370 Japanese Patent Laid-Open No. 2015-123395 Japanese Patent Laid-Open No. 2019-196854 Japanese Patent Laid-Open No. 2020-179337

[0010] An object of the present invention is to provide a flow path maintenance system and a flow path maintenance method that can suppress the formation of scale on the inner wall of a flow path and / or the corrosion of the inner wall of a flow path.

[0011] A flow path maintenance system according to one aspect of the present invention comprises: a flow path through which a hydrophilic liquid flows; a storage section provided at an outlet of the flow path and storing the hydrophilic liquid and a hydrophobic liquid having a specific gravity different from that of the hydrophilic liquid; a circulation flow path having one end connected to the section of the storage section where the hydrophobic liquid is stored and the other end connected to the flow path; and a pump provided in the circulation flow path and configured to generate a multiphase flow of the hydrophilic liquid and the hydrophobic liquid within the flow path by injecting the hydrophobic liquid stored in the storage section into the flow path.

[0012] In the flow path maintenance system, at least one of the liquid phases of the hydrophilic liquid and the hydrophobic liquid may be distributed continuously in the multiphase flow.

[0013] In addition, in the flow path maintenance system, the hydrophilic liquid may be a thermal fluid, a heat exchanger may be provided in the flow path, and the circulation flow path may be connected to the flow path via a connection part upstream of the heat exchanger.

[0014] The flow path maintenance system may further include a discharge pipe that discharges the hydrophilic liquid stored in the storage section.

[0015] Furthermore, in the flow path maintenance system, when the specific gravity of the hydrophobic liquid is greater than that of the hydrophilic liquid, the circulation flow path may be connected to the lower part of the storage section and the discharge pipe may be connected to the upper part of the storage section, and when the specific gravity of the hydrophobic liquid is less than that of the hydrophilic liquid, the circulation flow path may be connected to the upper part of the storage section and the discharge pipe may be connected to the lower part of the storage section.

[0016] The flow path maintenance system may further include a stirring means provided in the flow path for stirring the mixture of the hydrophilic liquid and the hydrophobic liquid.

[0017] In the flow path maintenance system, the hydrophobic liquid may be a non-polar solvent.

[0018] In the flow path maintenance system, the hydrophilic liquid may be a corrosive solution, and the flow path may be made of a corrosive material.

[0019] In the flow path maintenance system, the flow path may be made of a hydrophobic material, or an inner wall of the flow path may be coated with a hydrophobic material.

[0020] A flow path maintenance method according to one aspect of the present invention involves injecting a hydrophobic liquid having a different specific gravity from a hydrophilic liquid into a flow path through which the hydrophilic liquid flows, thereby forming a multiphase flow of the hydrophilic liquid and the hydrophobic liquid within the flow path.

[0021] In the flow path maintaining method, at least one of the hydrophilic liquid and the hydrophobic liquid may be continuously distributed in the multiphase flow.

[0022] In addition, in the flow path maintenance method, the mixed liquid of the hydrophilic liquid and the hydrophobic liquid flowing out of the flow path may be separated into the hydrophilic liquid and the hydrophobic liquid, and the separated hydrophobic liquid may be re-injected into the flow path.

[0023] In the flow path maintaining method, the mixed liquid of the hydrophilic liquid and the hydrophobic liquid flowing in the flow path may be agitated.

[0024] In the flow path maintaining method, the hydrophobic liquid may be a non-polar solvent.

[0025] In the flow path maintaining method, the hydrophilic liquid may be a thermal fluid, and the thermal fluid may flow in a heat exchanger provided in the flow path.

[0026] According to the present invention, it is possible to provide a flow path maintenance system and a flow path maintenance method that can suppress the formation of scale on the inner wall of the flow path and / or the corrosion of the inner wall of the flow path.

[0027] FIG. 1 is a diagram showing a schematic configuration of a scale inhibition system (flow path maintenance system) according to a first embodiment; FIG. 2 is an SEM image of the inner wall of a silicon tube; FIG. 3 is a diagram showing a schematic configuration of a scale inhibition system (flow path maintenance system) according to a second embodiment; FIG. 4 is a flowchart for explaining an example of a scale inhibition method (flow path maintenance method) according to an embodiment; and FIG. 5 is an example of a photograph taken of a multiphase flow (turbulent flow) flowing inside a transparent pipe.

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] First Embodiment A scale inhibition system 1 according to this embodiment will be described with reference to Fig. 1. The scale inhibition system 1 is configured as a flow path maintenance system that maintains the flow path by suppressing the formation of scale that adheres to the inner wall of a pipe 11 through which a hydrophilic liquid flows and by suppressing corrosion of the inner wall of the pipe 11.

[0030] The scale inhibition system 1 includes a pipe 11, a storage section 12, a circulation pipe 13, a pump 14, a discharge pipe 15, a heat exchanger 16, and a connection section 17. Each component will be described in detail below.

[0031] The pipe 11 is a flow path through which the hydrophilic liquid L1 flows. In this embodiment, the hydrophilic liquid L1 is a thermal fluid, for example, thermal source water such as hot spring water pumped from a thermal fluid source. The hydrophilic liquid L1 may also be a corrosive solution. The material of the pipe 11 is not particularly limited, but may be made of carbon steel, for example. The pipe 11 may also be a heat transfer pipe. The pipe 11 may also be a tube made of resin or the like, or a flexible pipe that can be bent freely. The pipe 11 is an example of a flow path within the scope of the claims.

[0032] The pipe 11 is provided with a heat exchanger 16 that utilizes a thermal fluid. The type of the heat exchanger 16 is not particularly limited, and may be, for example, a shell-and-tube heat exchanger, a plate heat exchanger, a spiral heat exchanger, or the like. The heat exchanger 16 is not an essential component, and the pipe 11 does not necessarily need to be provided with the heat exchanger 16. The flow path within the heat exchanger 16 is an example of a flow path in the claims.

[0033] The reservoir 12 is provided at the outlet of the pipe 11, and receives the liquid that has flowed through the pipe 11. The liquid that flows into the reservoir 12 is a mixture of a hydrophilic liquid L1 and a hydrophobic liquid L2. Note that the mixture in the present application does not include an emulsified liquid.

[0034] The hydrophobic liquid L2 has a different specific gravity from the hydrophilic liquid L1. Therefore, the mixed liquid that flows from the pipe 11 into the reservoir 12 separates into the hydrophilic liquid L1 and the hydrophobic liquid L2. In this embodiment, the specific gravity of the hydrophobic liquid L2 is greater than the specific gravity of the hydrophilic liquid L1.

[0035] 1 , the pipe 11 is connected to the top surface (lid) of the storage unit 12. The pipe 11 may also be connected to the side surface of the storage unit 12. Furthermore, if the storage unit 12 does not have a lid, the pipe 11 may not be connected to the storage unit 12, and the outlet of the pipe 11 may be located above the storage unit 12.

[0036] A hydrophilic liquid L1 and a hydrophobic liquid L2 having a larger specific gravity than the hydrophilic liquid L1 are stored in the reservoir 12. Due to the difference in specific gravity, the hydrophobic liquid L2 is stored in the lower part of the reservoir 12.

[0037] The hydrophobic liquid L2 is not particularly limited as long as it is a hydrophobic liquid. For example, the hydrophobic liquid L2 is a non-polar solvent such as silicone oil, a hydrocarbon compound, an aromatic hydrocarbon, an aromatic compound, a heterocyclic compound, a fluorine-based solvent, a chlorine-based solvent, or a bromine-based solvent. Specific examples of the hydrophobic liquid L2 include Novec (registered trademark), Fluorinert, paraffinic base oil, naphthenic base oil, trichloroethylene, dichloromethane, perchloroethylene, and 1-bromopropane. Note that when the hydrophilic liquid L1 is a thermal fluid, the hydrophobic liquid L2 may be a non-flammable or flame-retardant liquid.

[0038] The circulation pipe 13 is a flow path having one end connected to the storage section 12 and the other end connected to the pipe 11. Specifically, one end of the circulation pipe 13 is connected to a portion of the storage section 12 where the hydrophobic liquid L2 is stored so that the hydrophobic liquid L2 flows in. In this embodiment, the circulation pipe 13 is connected to the lower part of the storage section 12 (the lower side or bottom surface of the storage section 12). The other end of the circulation pipe 13 is connected to the pipe 11 via a connection part 17 upstream of the heat exchanger 16. The circulation pipe 13 may be a tube made of resin or the like, a flexible pipe that can be bent freely, or the like. The circulation pipe 13 is an example of a circulation flow path as defined in the claims. The connection part 17 is, for example, a branch joint.

[0039] Pump 14 is provided in circulation pipe 13 and injects hydrophobic liquid L2 stored in reservoir 12 into pipe 11. That is, when pump 14 is operated, hydrophobic liquid L2 stored in reservoir 12 is injected into pipe 11 through circulation pipe 13. As a result, a multiphase flow (liquid-liquid two-phase flow) of hydrophilic liquid L1 and hydrophobic liquid L2 is formed in pipe 11. In this multiphase flow, it is desirable that the distribution of at least one of the liquid phases, hydrophilic liquid L1 and hydrophobic liquid L2, is continuous. That is, in the multiphase flow of the present application, it is desirable that the distribution of both liquid phases (distribution in the longitudinal direction of pipe 11) is such that both liquid phases are continuous, or that one liquid phase is continuous and the other liquid phase is discontinuous. Such a multiphase flow can ensure contact between the hydrophobic liquid L2 and the inner wall of the pipe 11 and / or increase the surface area of ​​the interface between the two liquids where scale particles are likely to accumulate, thereby improving the effect of suppressing scale formation and / or corrosion. Furthermore, since the hydrophobic liquid L2 injected into the pipe 11 is efficiently heated by the thermal fluid of the hydrophilic liquid L1, a decrease in the efficiency of the heat exchanger 16 due to the injection of the hydrophobic liquid L2 can be suppressed. Note that the multiphase flow may be a three-phase flow including a gas phase. For example, if the hydrophilic liquid L1 is heat source water, the multiphase flow in the pipe 11 may include both the liquid phases of the hydrophilic liquid L1 and the hydrophobic liquid L2, as well as the vapor (gas phase) of the hydrophilic liquid L1.

[0040] The multiphase flow may be a laminar flow or a turbulent flow. In the case of a laminar flow, it is desirable that the hydrophobic liquid L2 has a spiral shape. In the case of a large-diameter pipe 11, it is desirable that the multiphase flow be a turbulent flow so that the hydrophobic liquid L2 can sufficiently contact the inner wall of the pipe 11.

[0041] Figure 5 shows an example of a photograph of a multiphase flow flowing through a polycarbonate pipe 11 in an evaluation system installed in a laboratory. The pipe 11 is a transparent tube with an inner diameter of approximately 100 mm. As can be seen from this photograph, turbulent flow is formed within the transparent tube. In this example, the hydrophilic liquid L1 is hot spring water, the hydrophobic liquid L2 is Fluorinert FC3283, and the ratio of the hydrophilic liquid L1 to the hydrophobic liquid L2 is 1:3.

[0042] The pump 14 does not need to be constantly operating, but may be operated intermittently or only when the pipe 11 is being cleaned. If the liquid in the reservoir 12 has not yet separated into the hydrophilic liquid L1 and the hydrophobic liquid L2, the pump 14 may be stopped until the liquid is separated. If the hydrophilic liquid L1 and the hydrophobic liquid L2 are to be emulsified, a salt may be added to the reservoir 12 or the like to promote separation of the two liquids from the emulsified state.

[0043] In addition, if it is necessary to prevent the hydrophobic liquid L2 injected into the piping 11 by the pump 14 from flowing back upstream of the piping 11, a pump or check valve may be provided upstream of the connection part 17 of the piping 11.

[0044] The discharge pipe 15 is a pipe for discharging the hydrophilic liquid L1 that has flowed through the pipe 11 into a drain or the like. The discharge pipe 15 discharges the hydrophilic liquid L1 stored in the storage section 12. The discharge pipe 15 is connected to the portion of the storage section 12 where the hydrophilic liquid L1 is stored so that the hydrophilic liquid L1 can flow in. In this embodiment, the discharge pipe 15 is connected to the upper part of the storage section 12. The discharge pipe 15 is not an essential component. For example, a discharge hole may be provided in the lid of the storage section 12, and the hydrophilic liquid L1 may be discharged to the outside through the hole.

[0045] The hydrophobic liquid L2 may be a liquid having a lower specific gravity than the hydrophilic liquid L1, such as silicone oil, paraffinic oil, naphthenic oil, etc. In this case, the circulation pipe 13 is connected to the upper part of the reservoir 12, and the discharge pipe 15 is connected to the lower part of the reservoir 12.

[0046] As described above, according to this embodiment, the hydrophobic liquid L2 is injected into the pipe 11 through which the hydrophilic liquid L1 flows, and a multiphase flow of the hydrophilic liquid L1 and the hydrophobic liquid L2 is formed in the pipe 11. The multiphase flow flows through the pipe 11 toward the reservoir 12. This reduces contact of the hydrophilic liquid L1 with the inner wall of the pipe 11, thereby suppressing the formation of scale on the inner wall of the pipe 11. Furthermore, it is possible to suppress the formation of scale over almost the entire pipe 11, rather than just a portion of the pipe 11.

[0047] Furthermore, according to this embodiment, the hydrophobic liquid L2, which has a relatively large specific gravity, strips off scale adhering to the inner walls of the pipe 11, thereby cleaning the pipe 11. Also, the hydrophobic liquid L2 strips off scale adhering to the inner walls of the flow paths of the heat exchanger 16, thereby cleaning the flow paths within the heat exchanger 16. In this embodiment, the hydrophobic liquid L2 contained in the mixed liquid is constantly in contact with the inner walls of the flow paths, thereby constantly providing the function of stripping off scale. Another advantage is that there is no need to stop the flow of the hydrophilic liquid, such as heat source water, in order to fill the flow paths with the cleaning liquid.

[0048] Furthermore, according to this embodiment, it is not necessary to stop the flow of the hydrophilic liquid L1, so the availability of the heat exchanger 16 can be improved.

[0049] Furthermore, according to this embodiment, the mixed liquid that has flowed through the pipe 11 is stored in the reservoir 12, and the hydrophobic liquid L2 that has separated from the mixed liquid due to the difference in specific gravity is re-injected into the pipe 11. Since the hydrophobic liquid L2 is recovered and reused in this manner, it is possible to reduce the running costs of the scale inhibition system 1. Furthermore, since the hydrophobic liquid L2 is prevented from leaking out of the scale inhibition system 1, it is possible to increase the tolerance for using a liquid that has a relatively large environmental impact as the hydrophobic liquid L2.

[0050] Furthermore, the flow path maintenance system of this embodiment can be constructed without making major changes to an existing flow path. For example, if the piping 11 is already installed, the flow path maintenance system can be constructed easily and at low cost by adding the reservoir 12, the circulation piping 13, and the pump 14.

[0051] Furthermore, according to this embodiment, the hydrophobic liquid L2 comes into contact with the inner wall of the pipe 11, thereby suppressing corrosion of the pipe 11. Furthermore, the hydrophobic liquid L2 comes into contact with the inner wall of the flow path of the heat exchanger 16, thereby suppressing corrosion of the inner wall of the flow path of the heat exchanger 16.

[0052] From the viewpoint of pipe maintenance effect, it is preferable that the multiphase flow flowing through pipe 11 is a spiral laminar flow (spiral flow) or a turbulent flow. To make the multiphase flow turbulent, the ratio of the hydrophobic liquid L2 in the mixture of hydrophilic liquid L1 and hydrophobic liquid L2 may be higher than that of the hydrophilic liquid L1. For example, the ratio of the hydrophilic liquid L1 to the hydrophobic liquid L2 is set to 1:3. By increasing the ratio of the hydrophobic liquid L2, it is possible to ensure contact between the hydrophobic liquid L2 and the inner wall of pipe 11 and / or increase the surface area of ​​the interface between the two liquids where scale particles are likely to accumulate, and an improved suppression effect can be expected.

[0053] The pipe 11 may be made of a hydrophobic material, or the inner wall of the pipe 11 may be coated with a hydrophobic material. This allows the hydrophobic liquid L2 to easily come into contact with the inner wall of the pipe 11, thereby further suppressing the formation of scale on the inner wall of the flow path and / or the corrosion of the inner wall of the flow path. Examples of hydrophobic materials include silicone, fluorine compounds, paraffin, polypropylene, etc. Furthermore, if the hydrophilic liquid L1 is a corrosive solution or if the hydrophobic liquid L2 contains scale components, a hydrophilic material may be used for the material of the pipe 11 and / or the coating of the inner wall.

[0054] <Experimental Results 1> Here, the results of an experiment investigating the scale inhibition effect in an evaluation system will be described. In the evaluation system, a heat-resistant silicone tube (diameter 4 mm) was used as the piping 11, hot spring water was used as the hydrophilic liquid L1, and Novec 7300 was used as the hydrophobic liquid L2. The hot spring water was allowed to flow through the silicone tube at room temperature for approximately one day.

[0055] Figure 2 shows the experimental results, showing images of the inner wall of a silicon tube cut open and observed with a scanning electron microscope (SEM) for the cases where hydrophobic liquid L2 was injected (right) and where hydrophobic liquid L2 was not injected (left). Figure 2 clearly shows that less scale S adhered to the inner wall was observed for the case where hydrophobic liquid L2 was injected.

[0056] <Experimental Results 2> Next, the results of an experiment investigating the corrosion suppression effect of a pipe in an evaluation system will be described. In the evaluation system, a carbon steel pipe (SGP black steel pipe, size 10A) made of a corrosive material was used as the pipe 11, a corrosive solution (a 3% hydrogen chloride solution) was used as the hydrophilic liquid L1, and Fluorinert (FC3283) was used as the hydrophobic liquid L2. The hydrophilic liquid L1 and the hydrophobic liquid L2 were mixed in a 1:1 ratio and allowed to flow (circulate) within the carbon steel pipe at room temperature for 90 hours. The weight of the carbon steel pipe was then measured, and the difference (loss) from the weight before the experiment was determined.

[0057] The experimental results are shown in Table 1. In Table 1, "Conventional" indicates the results when the hydrophobic liquid L2 was not flowed, and "Embodiment" indicates the results when the hydrophobic liquid L2 was flowed together with the hydrophilic liquid L1. From these results, it can be seen that the weight loss due to corrosion was significantly reduced in the embodiment compared to the conventional example. In this way, by flowing a mixture of the hydrophilic liquid (corrosive solution) and the hydrophobic liquid, the time that the corrosive solution is in contact with the surface of the pipe is reduced, thereby suppressing corrosion of the pipe.

[0058]

[0059] Second Embodiment Next, a scale prevention system 1A according to a second embodiment will be described with reference to Fig. 3. As in the first embodiment, the scale prevention system 1A is configured as a flow path maintenance system. In Fig. 3, components having the same functions as those in the first embodiment are denoted by the same reference numerals as in Fig. 1.

[0060] The difference between the first embodiment and the second embodiment is that in the second embodiment, a pump for stirring the mixed liquid is provided in the pipe 11. The second embodiment will be described below, focusing on the difference.

[0061] The scale inhibition system 1A includes a pipe 11, a storage section 12, a circulation pipe 13, a pump 14, a discharge pipe 15, a heat exchanger 16, a connection section 17, and a pump 18. The configuration other than the pump 18 is the same as that of the first embodiment.

[0062] The pump 18 is provided in the pipe 11. More specifically, the pump 18 is provided between the heat exchanger 16 and the connection part 17, and agitates the mixture of the hydrophilic liquid L1 and the hydrophobic liquid L2 flowing in the pipe 11. The pump 18 is an example of the agitation means in the claims.

[0063] By stirring the mixed liquid with pump 18, hydrophobic liquid L2 is dispersed and becomes more likely to come into contact with the inner wall of pipe 11. As a result, it is possible to further suppress the formation of scale on the inner wall of pipe 11 and / or corrosion of the inner wall of pipe 11. Furthermore, according to the second embodiment, even when the diameter of pipe 11 is relatively large, contact between hydrophobic liquid L2 and the inner wall of pipe 11 is more easily ensured and / or the surface area of ​​the interface between the two liquids is increased, thereby effectively suppressing the formation of scale and / or corrosion of the pipe.

[0064] It should be noted that pump 18 need not be provided as long as the means is capable of stirring the mixed liquid. For example, the mixed liquid may be stirred by rotating a plate-shaped, propeller-shaped, or other stirring bar within pipe 11. Also, a baffle plate that blocks the flow of the mixed liquid may be provided at connection portion 17 or the like. Such a stirring bar is an example of stirring means within the scope of the claims.

[0065] In addition, a pump or a check valve may be provided upstream of the connection part 17 of the pipe 11 to prevent the mixed liquid stirred by the pump 18 from flowing back upstream of the pipe 11 .

[0066] <Flow Path Maintenance Method> Next, an example of a flow path maintenance method according to this embodiment will be described with reference to the flowchart of FIG.

[0067] Step S1: A hydrophobic liquid is injected into a flow path such as a pipe through which a hydrophilic liquid flows, and a mixture of the hydrophilic liquid and the hydrophobic liquid is caused to flow within the flow path. Specifically, in the scale inhibition system 1, the pump 14 is operated to draw the hydrophobic liquid L2 stored in the reservoir 12 into the circulation pipe 13, and the hydrophobic liquid L2 is injected into the pipe 11 through the connection part 17. As a result, a mixture of the hydrophilic liquid L1 and the hydrophobic liquid L2 flows within the pipe 11.

[0068] Step S2: The mixed liquid that has passed through the flow path is separated into a hydrophilic liquid and a hydrophobic liquid. Specifically, in the scale inhibition system 1, the mixed liquid that has flowed out from the pipe 11 is allowed to stand in the storage section 12 and separated into a hydrophilic liquid L1 and a hydrophobic liquid L2. In this embodiment, since the hydrophobic liquid L2 has a larger specific gravity than the hydrophilic liquid L1, the hydrophobic liquid L2 accumulates in the lower part of the storage section 12 when the mixed liquid is allowed to stand.

[0069] Step S3: Reinject the separated hydrophobic liquid into the flow path. Specifically, in the scale prevention system 1, the hydrophobic liquid L2 separated from the hydrophilic liquid L1 in the storage section 12 is reinjected into the pipe 11 via the circulation pipe 13.

[0070] The above method is merely an example, and various modifications are possible. For example, in step S2, scale that has flowed from pipe 11 may accumulate near the boundary between hydrophilic liquid L1 and hydrophobic liquid L2 stored in reservoir 12. A step of removing this scale may be provided.

[0071] Alternatively, step S2 may be omitted. That is, the hydrophobic liquid L2 may be injected into the pipe 11 before the mixed liquid that has flowed into the reservoir 12 separates into the hydrophilic liquid L1 and the hydrophobic liquid L2. If the capacity of the reservoir 12 is sufficiently large compared to the amount of liquid flowing out of the pipe 11, or if the circulation pipe 13 is connected to the bottom surface of the reservoir 12, and the inlet of the circulation pipe 13 is always in contact with the hydrophobic liquid L2, it is possible to draw the hydrophobic liquid L2 into the circulation pipe 13 without waiting for the mixed liquid that has flowed into the reservoir 12 to separate into the hydrophilic liquid L1 and the hydrophobic liquid L2.

[0072] In step S1, the mixed liquid of the hydrophilic liquid L1 and the hydrophobic liquid L2 may be stirred. In this case, in the scale prevention system 1A, the mixed liquid is stirred by a pump 18 provided in the piping 11. Note that the mixed liquid may also be stirred by a stirring means other than a pump.

[0073] Based on the above description, a person skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the above-described embodiments. Various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and spirit of the present invention, which is derived from the content defined in the claims and their equivalents.

[0074] 1, 1A Scale suppression system 11 Piping 12 Storage section 13 Circulation piping 14, 18 Pump 15 Discharge pipe 16 Heat exchanger 17 Connection section L1 Hydrophilic liquid L2 Hydrophobic liquid

Claims

1. A channel through which a hydrophilic liquid flows, A storage section is provided at the outlet of the aforementioned flow path, where the hydrophilic liquid and a hydrophobic liquid with a specific gravity different from that of the hydrophilic liquid are stored. A circulation channel is provided, with one end connected to the portion of the storage section where the hydrophobic liquid is stored, and the other end connected to the flow channel. A pump provided in the circulation channel, which generates a multiphase flow of the hydrophilic liquid and the hydrophobic liquid in the channel by injecting the hydrophobic liquid stored in the storage section into the channel, A flow path maintenance system equipped with the following features.

2. The system according to claim 1, wherein in the multiphase flow, the distribution of at least one of the two liquid phases, the hydrophilic liquid and the hydrophobic liquid, is continuous.

3. The system according to claim 1, wherein the hydrophilic liquid is a thermal fluid, a heat exchanger is provided in the flow path, and the circulating flow path is connected to the flow path via a connection upstream of the heat exchanger.

4. The system according to claim 1, further comprising a discharge pipe for discharging the hydrophilic liquid stored in the storage section.

5. If the specific gravity of the hydrophobic liquid is greater than that of the hydrophilic liquid, the circulation channel is connected to the lower part of the storage section, and the discharge pipe is connected to the upper part of the storage section. The system according to claim 4, wherein, when the specific gravity of the hydrophobic liquid is less than that of the hydrophilic liquid, the circulation channel is connected to the upper part of the storage section and the discharge pipe is connected to the lower part of the storage section.

6. The system according to any one of claims 1 to 5, further comprising a stirring means provided in the flow path for stirring a mixture of the hydrophilic liquid and the hydrophobic liquid.

7. The system according to claim 1, wherein the hydrophobic liquid is a nonpolar solvent.

8. The system according to claim 1, wherein the hydrophilic liquid is a corrosive solution and the material of the channel is a corrosive material.

9. The system according to claim 1, wherein the channel is made of a hydrophobic material, or the inner wall of the channel is coated with a hydrophobic material.

10. A method for maintaining a flow path, comprising injecting a hydrophobic liquid with a different specific gravity from the hydrophilic liquid into a flow path through which a hydrophilic liquid flows, thereby forming a multiphase flow of the hydrophilic liquid and the hydrophobic liquid.

11. The method according to claim 10, wherein in the multiphase flow, the distribution of at least one of the two liquid phases, the hydrophilic liquid and the hydrophobic liquid, is continuous.

12. The method according to claim 10, wherein the mixture of the hydrophilic liquid and the hydrophobic liquid discharged from the channel is separated into the hydrophilic liquid and the hydrophobic liquid, and the separated hydrophobic liquid is reinjected into the channel.

13. The method according to claim 10, wherein a mixture of the hydrophilic liquid and the hydrophobic liquid flowing in the channel is stirred.

14. The method according to claim 10, wherein the hydrophobic liquid is a nonpolar solvent.

15. The method according to any one of claims 10 to 14, wherein the hydrophilic liquid is a thermal fluid, and the thermal fluid flows within a heat exchanger provided in the flow path.