How to select a descaling agent

Abstract

The purpose of the present invention is to provide a method for selecting a chemical agent for scale removal use which is suitable for scales and a base material. Provided is a method for selecting a chemical agent for scale removal use, the method comprising: a step for obtaining a coordinate A of an inherent physical value based on a Hansen solubility parameter for the whole of a target scale; a step for obtaining a coordinate B of an inherent physical value based on a Hansen solubility parameter for a base material-side surface of the target scale; a step for obtaining a coordinate C of an inherent physical value based on a Hansen solubility parameter for a target base material; a step for selecting a penetrating agent having a coordinate D of an inherent physical value based on a Hansen solubility parameter, on the basis of an interaction radius Ra of the target scale which is centered on the coordinate A; a step for selecting a peeling agent having a coordinate E of an inherent physical value based on a Hansen solubility parameter, on the basis of the positional relationship between the coordinate B and the coordinate C; and a step for selecting an inducing agent having a coordinate F of an inherent physical value based on a Hansen solubility parameter, on the basis of the positional relationship between the coordinate D and the coordinate E.

Description

[Technical field]

[0001] The present invention relates to a method for selecting a descaling agent and a method for removing scale. [Background technology]

[0002] 2. Description of the Related Art Conventionally, scale deposition has been a problem in systems that include a fluid distribution system, such as power plant systems, ship systems, boiler systems, and steel plant systems.

[0003] Various chemicals and devices have been used to remove scale. For example, oxidizing agents such as hydrofluoric acid, acetic acid, sulfuric acid, and hydrochloric acid, as well as alkaline agents such as sodium hydroxide, sodium carbonate, and sodium bicarbonate, have been used in geothermal power generation to dissolve and clean silica scale. These agents have been used by chemically reacting with the compounds that form the scale, dissolving it from the surface layer.

[0004] A scale removing device for a geothermal power generation steam turbine is known, which is configured to inject steam pressurized to a predetermined pressure toward the surface of a nozzle and / or blade arranged in the geothermal power generation steam turbine (see, for example, Patent Document 1). Also known is a scale remover that contains tropolones and optionally contains at least one of hydrochloric acid, sulfuric acid, and nitric acid, and has a pH adjusted to 1 to 2 (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-220850 A [Patent Document 2] JP 2013-202424 A Summary of the Invention [Problem to be solved by the invention]

[0006] Among plant systems where scale is an issue, geothermal power plants have a high concentration of dissolved silica in the geothermal water that flows through them. For example, while the dissolved silica concentration in cooling water is a maximum of about 150 ppm, the dissolved silica concentration in geothermal water in Japan is as high as 450 to 900 ppm. This has led to the problem that scale such as amorphous silica is easily precipitated.

[0007] In addition, silica-based scale components vary greatly depending on the power plant. This is thought to be due to differences in the dissolved metals contained in the geothermal water, but it has been difficult to select the optimal scale inhibitor for each power plant.

[0008] Conventionally, the widely used method of removing scale using oxidizing agents or alkaline agents involves chemical reactions. This has led to problems such as the generation of unexpected deposits (reaction products), poor cleaning, and the generation of harmful gases. It is desirable to select the most suitable agent for the scale components of each plant. [Means for solving the problem]

[0009] The inventors of the present invention have investigated the selection of scale removal agents based on the Hansen solubility parameter (HSP) and the Hansen solubility sphere in order to select an agent for removing scale according to the components of the scale. In particular, they have focused on not only the surface scale composition but also the scale composition in the area in contact with the base material and the composition of the base material, and have come up with the idea of ​​selecting a scale removal agent from the viewpoint of weakening the adhesive force at the adhesion interface of the scale, thus completing the present invention.

[0010] That is, according to one embodiment, the present invention provides a method for selecting a scale removing agent, comprising the steps of: A step of obtaining a coordinate A of an intrinsic property value based on the Hansen solubility parameters of the entire target scale; A step of obtaining coordinates B of intrinsic physical property values ​​based on the Hansen solubility parameters of the surface of the target scale on the base material side; A step of obtaining a coordinate C of an intrinsic property value based on the Hansen solubility parameter of the target base material; A step of selecting a penetrant having a coordinate D of an intrinsic property value based on the Hansen solubility parameters based on the interaction radius Ra of the target scale centered on the coordinate A; A step of selecting a stripping agent having a coordinate E of an intrinsic physical property value based on the Hansen solubility parameters based on the positional relationship between the coordinate B and the coordinate C; A step of selecting an inducer having a coordinate F of an intrinsic physical property value based on the Hansen solubility parameters based on the positional relationship between the coordinate D and the coordinate E; The present invention relates to a method for selecting a scale removing agent, comprising:

[0011] In the method for selecting a scale removing agent, when the coordinates of the intrinsic physical property values ​​are expressed as three-dimensional coordinates consisting of a dispersion force δD, a dipole-dipole force δP, and a hydrogen bond force δH, the coordinate A is (δDA, δPA, δHA), the coordinate D is (δDD, δPD, δHD), and the interaction radius is Ra, the step of selecting the penetrant is carried out by using the following formula (I): 4(δDA-δDD)^2+(δPA-δPD)^2+(δHA-δHD)^2 ≦ (Ra)^2 (I) It is preferable to select a substance having a coordinate D that satisfies the following formula as the penetrant:

[0012] In the method for selecting a scale removing agent, when the coordinate B is (δDB, δPB, δHB), the coordinate C is (δDC, δPC, δHC), the coordinate E is (δDE, δPE, δHE), and the interaction radius is Ra, the step of selecting the stripping agent is performed by selecting, based on the Hansen sphere method, a coordinate E that is within a region represented by a locus of a sphere whose center is on a line segment BC and whose radius is Ra, and which satisfies the following formula (II): (δDB, δPB, δHB) ≦(δDE, δPE, δHE) ≦(δDC, δPC, δHC) or (δDB, δPB, δHB) > (δDE, δPE, δHE) > (δDC, δPC, δHC) (II) It is preferable to select a substance having a coordinate E that satisfies the following formula as the release agent.

[0013] In the method for selecting a scale removal agent, when the coordinate F is (δDF, δPF, δHF) and the interaction radius is Ra, the step of selecting an inducer includes a step of selecting an inducer based on the Hansen sphere method, in which the coordinate F is within a region represented by a locus of a sphere whose center is on a line segment DE and whose radius is Ra, and which satisfies the following formula (III): (δDD, δPD, δHD) ≦(δDF, δPF, δHF) ≦(δDE, δPE, δHE) or (δDD, δPD, δHD) > (δDF, δPF, δHF) > (δDE, δPE, δHE) (III) It is preferable to select a substance having a coordinate F that satisfies the following formula as the inducer.

[0014] According to another embodiment, the present invention relates to a method for descaling, comprising: Selecting a penetrating agent, a guide agent, and a stripping agent based on the selection method described in any one of the above; applying the penetrant, inducer, and stripper selected in the selecting step to the target scale in that order or substantially simultaneously; The present invention relates to a method for removing scale comprising the steps of:

[0015] The scale removal method preferably further comprises the step of applying a physical force to the target scale and / or the step of applying a corrosion inhibitor to the target scale.

[0016] According to yet another embodiment, the present invention relates to a method for descaling a geothermal power generation system, comprising: A step of selecting a penetrating agent, a guide agent, and a stripping agent for a plurality of devices constituting a geothermal power generation system based on the selection method described in any one of the above, for the devices; applying the penetrant, inducer, and stripper selected in the selecting step to the target scale in this order or substantially simultaneously for each of the plurality of devices; The present invention relates to a method for removing scale comprising the steps of: Effect of the Invention

[0017] According to the method for selecting a scale removing agent of the present invention, it is possible to select a combination of agents having generally different functions, namely a penetrant, an inducer, and a stripper, by using the HSP technique, taking into consideration the target scale, the base material to which the scale adheres, and the scale composition at the interface with the base material. Therefore, it is possible to select an optimal combination of agents for a plant where scale adhesion is a problem, and / or an optimal combination of agents for a scale adhesion site within the same plant. The selection method of the present invention focuses on the adhesive force at the interface, and can decompose and remove scale without substantially causing chemical changes, thereby suppressing the generation of precipitates and poor cleaning. As a result, it is possible to shorten the mechanical cleaning period in the subsequent process. In addition, since the HSP technique can be used to select a combination of agents from multiple options, it is also possible to exclude dangerous agents such as hydrofluoric acid that have been commonly used. Therefore, it is possible to avoid the risk of generating toxic gases and simplify the treatment of industrial waste. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram for explaining an example of a method for selecting a scale removal agent according to a first embodiment of the present invention, and is a diagram conceptually showing the coordinates of intrinsic physical property values ​​based on the Hansen solubility parameters for the entire scale, the surface of the scale base material, the base material, the penetrating agent, the inducer, and the stripping agent. [Diagram 2] FIG. 2 is a conceptual diagram showing a cylinder that serves as a selection region when selecting a stripping agent based on the surface of the scale base material and the coordinates of the base material. [Diagram 3]FIG. 3 is a diagram conceptually showing the mechanism of scale removal when a penetrating agent, an inducer, and a stripping agent are applied to the scale and base material in this order in a scale removal method according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a diagram conceptually illustrating an example of a geothermal power generation system to which a scale removal method according to a fourth embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment described below.

[0020] [First embodiment: Method for selecting scale removal agent] According to a first embodiment, the present invention relates to a method for selecting a scale removing agent. The selection method includes the following steps. (1) A process of obtaining the coordinate A of the intrinsic physical property value based on the Hansen solubility parameters of the entire target scale (2) A process of obtaining coordinate B of the intrinsic physical property value based on the Hansen solubility parameters of the surface of the target scale on the base metal side (3) A process of obtaining the coordinate C of the intrinsic physical property value based on the Hansen solubility parameter of the target base material (4) A step of selecting a penetrant having a coordinate D of an intrinsic physical property value based on the Hansen solubility parameters based on the interaction radius Ra of the target scale centered on the coordinate A. (5) A step of selecting a stripping agent having a coordinate E of an intrinsic physical property value based on the Hansen solubility parameters based on the positional relationship between the coordinate B and the coordinate C. (6) A step of selecting an inducer having a coordinate F of an intrinsic physical property value based on the Hansen solubility parameters based on the positional relationship between the coordinate D and the coordinate E.

[0021] The scale removing agent in the present invention is selected for the purpose of removing specific scale that has adhered to a specific base material in a facility such as a plant where adhesion of scale is a concern. Hereinafter, in this specification, a specific area where scale adheres and requires removal is referred to as an adhesion area. In addition, in the facility, the material of the surface to which scale adheres, such as equipment, is referred to as the target base material, and the attached scale is referred to as the target scale.

[0022] In the present invention, the scale removal agent refers to an agent used to remove scale, and typically refers to a combination of agents consisting of three types of agents selected by the method of this embodiment: a penetrating agent, an inducer, and a stripping agent. The penetrating agent penetrates the entire scale, forms cracks in the scale, and functions to promote the formation of a path from the surface of the scale through the inside of the scale to the interface with the base material. The inducer functions to promote the introduction of the stripping agent using the path to the interface formed by the penetrating agent. The stripping agent is an agent that has high affinity with the scale adhesion surface, and functions to reduce the adhesion of the scale to the base material by penetrating the adhesion part. In general, the penetrating agent, inducer, and stripping agent that constitute the scale removal agent are selected as separate and different agents. However, depending on the composition of the scale and the base material, the scale removal agent may be selected such that two or all of the penetrating agent, inducer, and stripping agent are the same substance.

[0023] The penetrating agent, the inducing agent, and the stripping agent may be a drug composed of one kind of substance, or may be a mixture of two or more kinds of substances. In this specification, a penetrating agent composed of a single substance is also referred to as a single penetrating agent. Also, a penetrating agent composed of a mixture of two or more kinds of substances is also referred to as a mixed penetrating agent. Similarly, the inducing agent may be a single inducing agent or a mixed inducing agent, and the stripping agent may be a single stripping agent or a mixed stripping agent.

[0024] The target scale may be any scale that may contain inorganic compounds and organic compounds. More specifically, the target scale may be scale that is generated and adhered to a fluid substance such as flowing water in a power plant system such as geothermal, thermal, atomic, hydroelectric, or biomass power plant system, a ship system such as an exhaust gas cleaning system (EGCS) or a seawater desalination system, a factory heating heat source, a boiler system for heating and hot water supply in a building, a cooling water system, a cleaning water system, or other steel plant system, and the like, and the type of the scale is not particularly limited. For example, in a geothermal power plant, the target scale may be scale that is formed in layers on a substrate such as a pipe, a heat exchanger, a turbine, or a drain that constitutes the plant, and is made of multiple components.

[0025] The intrinsic physical property values ​​based on the Hansen solubility parameters are based on three-dimensional coordinates consisting of three intrinsic physical property values: dispersion force δD, dipole-dipole force δP, and hydrogen bond force δH. Hereinafter, the coordinates of the intrinsic physical property values ​​based on the Hansen solubility parameters will be abbreviated as HSP coordinates.

[0026] (1) A process for obtaining HSP coordinate A of the entire target scale In the first step, the HSP coordinate A of the entire target scale is obtained. The "HSP coordinate A of the entire target scale" refers to the HSP coordinate that reflects the characteristics of the averaged composition of the scale, which is generally a natural product or by-product in which various compounds are unevenly layered. The HSP coordinate A of the entire target scale can generally be obtained by a scale dissolution experiment, although values ​​reported in databases or literature may be used.

[0027] For example, a scale dissolution experiment can be carried out as follows. The scale used in the dissolution experiment can be collected from the target site of a plant or the like where the selected agent is applied. When collecting the scale, it is preferable to maintain the shape of the scale from the fluid contact surface to the base material contact surface. For example, it is preferable to collect a scale of 50 g or more in dry weight for analysis. However, even if the shape is distorted, each interface part can be distinguished by microscopic observation, and even if the weight is small, it is possible to perform an analysis to obtain the HSP coordinates of the entire target scale by combining with composition analysis. Next, multiple solvents with known HSP coordinates are prepared, and a specified amount of the collected scale is added to each solvent to confirm whether the scale dissolves in the solvent. The criteria for determining whether the scale dissolves in the solvent are preferably a particle size distribution meter, the weight of the residue after filtration, or differential thermogravimetric analysis (TG-DTA) for the solvent after adding the scale, but it can also be judged visually. The Hansen solubility parameters of chemical substances such as solvents can be obtained from a database. Furthermore, if the structure of a substance is known, the Hansen solubility parameters of the substance can be obtained using the Hansen Solubility Parameter software HSPiP (Hansen Solubility Parameter in Practice). The HSP coordinates of multiple solvents determined to dissolve the scale are then plotted in a three-dimensional coordinate space, and the coordinates of the center of the sphere formed by these coordinates can be set as the HSP coordinate A (δDA, δPA, δHA) of the entire target scale. The process of extrapolating the sphere based on multiple coordinate data and determining the center coordinates can be performed using commercially available software, for example, the same HSPiP as above.

[0028] (2) A process for obtaining the HSP coordinate B of the surface of the target scale on the base material side In the second step, the HSP coordinate B of the base metal side surface of the target scale is obtained. The base metal side surface of the target scale refers to the part of the target scale that corresponds to the interface that contacts the base metal. The HSP coordinate B of the base metal side surface of the target scale can be obtained by an analytical experiment of the scale interface.

[0029] An analysis experiment of the scale interface can be carried out, for example, as follows. A scale is grown on a test piece made of the same material as the target base material, using a fluid with the same composition as the fluid flowing through the adhesion site of the target scale. Then, a cross section of the scale grown on the test piece is observed by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) to identify the interface (local) composition. The local composition of the interface refers to a region with a depth of about tens to hundreds of nm, for example, about 10 nm to 900 nm, from the interface. Once the local composition of the interface is identified, the coordinates B (δDB, δPB, δHB) can be identified by checking against a separately constructed inorganic HSP database. More specifically, elements and their composition ratios are obtained by SEM-EDX, and compounds and their composition ratios are estimated. Next, the HSP coordinates of each compound are obtained by referring to the database, and the HSP coordinates B of the base material side surface of the target scale can be obtained according to the method of determining the HSP coordinates of a mixture described later.

[0030] (3) A process to obtain the HSP coordinate C of the target base material In the third step, the HSP coordinate C of the target base material is obtained. The HSP coordinate C of the target base material is the HSP coordinate of the outermost surface of the base material. Therefore, even if the scale adhesion site is a pipe and the pipe itself is made of steel, if a coating is provided on the surface, the HSP coordinate of the coating surface is obtained. The HSP coordinate C of the target base material can sometimes use values ​​reported in databases or literature, but can generally be obtained by analyzing the HSP of the base material surface using the contact angle method.

[0031] In the contact angle method, multiple solvents with known HSP coordinates are prepared as in the first step. These solvents are titrated onto the target base material to measure the contact angle (wettability). The criteria for determining whether the wettability is good or bad differ depending on the material, and the criteria can be appropriately determined by a person skilled in the art depending on the material. For example, for metal-based materials, wettability can be determined as good when the contact angle θ is 20° or less, and as bad when it exceeds this. Next, the HSP coordinates of multiple solvents determined to have good wettability are plotted on a three-dimensional coordinate space, and the coordinates of the center of the sphere formed by these coordinates can be set as the HSP coordinates C (δDC, δPC, δHC) of the target base material.

[0032] Although the above steps (1) to (3) are referred to as the first, second and third steps for the sake of convenience, these steps can be carried out independently in any order.

[0033] (4) A step of selecting a penetrant having HSP coordinate D. The fourth step is a step of selecting a penetrant having an HSP coordinate D, and is a step of selecting a penetrant based on the HSP coordinate A of the entire target scale. A substance having a high affinity with the entire target scale is selected as the penetrant. More specifically, if the coordinate D of the penetrant is (δDD, δPD, δHD) and the interaction radius is Ra, a substance having the coordinate D that satisfies the following formula (I) in relation to the coordinate A obtained in the first step is selected as the penetrant. 4(δDA-δDD)^2+(δPA-δPD)^2+(δHA-δHD)^2 ≦ (Ra)^2 (I)

[0034] Here, the interaction radius Ra is a value that indicates the range of substances that have affinity for a given HSP coordinate, and the interaction radius Ra can be determined according to the purpose and application. It can be said that the smaller the interaction radius Ra of a substance is for a given HSP coordinate, the stronger the interaction is. It is preferable that the upper limit of Ra is small, but it can be set to, for example, 5 (MPa) depending on the target specifications. 1 / 2 ) and may be 4.5, 4, 3.5, 3, 2.5, or 2 or less.

[0035] FIG. 1 is a diagram conceptually showing an HSP three-dimensional coordinate space in which the selection method according to this embodiment is implemented. In the figure, A represents the HSP coordinates of the entire target scale, and a sphere having an interaction radius Ra is represented by a virtual line with the coordinate A as its center. In this case, the penetrant is a substance having coordinate D, and can be said to be a substance having coordinates on the sphere and inside the sphere. When there are multiple applicable candidate substances, it is preferable to select a substance having coordinates closer to coordinate A as the penetrant. However, the penetrant can also be selected taking into consideration not only the distance between the coordinates A and D, but also the ease of handling and price of the substance.

[0036] Here, the term "substance" is not limited to substances that exist as simple compounds, but also includes monomers (repeating units) that can form polymers and compound parts such as modifying groups. The HSP coordinates of such single compounds and substances containing monomers and modifying groups can be selected from known substances in databases, literature, etc. In conventional techniques, agents for removing scale were selected from known compounds, but the use of HSP technology has the advantage of making it possible to select a more appropriate substance from a wider range of options including monomers and functional groups.

[0037] A mixed penetrant consisting of two or more substances can also be selected. The HSP coordinates of a mixture can generally be expressed as the sum of the molar fractions of the HSP coordinates of its constituent substances. For example, the HSP coordinates of a mixture in which the first substance is mixed at x (mol%) and the second substance is mixed at y (mol%) are expressed as the HSP coordinates of the first substance m 1 (δDm 1 , δPm 1 , δHm 1 ), the HSP coordinate of the second material m 2 (δDm 2 , δPm 2 , δHm 2 ), it can be expressed as follows, where x+y=100(mol%). {(δDm 1 ×x / 100+δDm 2 ×y / 100), (δPm 1×x / 100+δPm 2 ×y / 100), (δHm 1 ×x / 100+δHm 2 ×y / 100)} Therefore, if the HSP coordinates of such a mixture satisfy the above formula (I), the mixed penetrant can be treated and selected in the same way as a single-substance penetrant. The HPS coordinates of a mixture of three or more substances can be obtained in the same way by summing the values ​​obtained by multiplying the HSP coordinates of each component by the molar fraction.

[0038] The fourth step can be performed once the coordinate A of the first step is determined, and can be performed in any order, regardless of the second and third steps. It can also be performed independently of the fifth step, which will be described later, in any order.

[0039] (5) A step of selecting a release agent having HSP coordinate E. The fifth step is to select a stripping agent having an HSP coordinate E based on the positional relationship between the coordinate B and coordinate C. The stripping agent can be selected from substances having an HSP that is intermediate between the HSP of the surface of the scale on the base material side and the HSP of the target base material. Specifically, if the coordinate E of the stripping agent is (δDE, δPE, δHE) and the interaction radius is Ra, then, in relation to the coordinate B obtained in the second step and the coordinate C obtained in the third step, a substance is selected that has coordinate E within a region represented by the locus of a sphere whose center is on the line segment BC and whose radius is Ra, and that satisfies the following formula (II): (δDB, δPB, δHB) ≦(δDE, δPE, δHE) ≦(δDC, δPC, δHC) or (δDB, δPB, δHB) > (δDE, δPE, δHE) > (δDC, δPC, δHC) (II)

[0040] The selection of the coordinate E that satisfies the above conditions and formula (II) will be further explained with reference to Fig. 1 and Fig. 2. In Fig. 1, B represents the HSP coordinate of the surface of the scale on the base material side, and C represents the HSP coordinate of the target base material. In this case, the coordinate E is selected from the area represented by the locus of a sphere with a radius of Ra, whose center is on the line segment connecting B and C. In other words, the coordinate E is selected from the surface and inside of the area in which a hemisphere with a radius of Ra is added to the two bottom surfaces of a cylinder with a radius of Ra, with the line segment BC as the central axis. Note that the area discussed under this condition is Hansen's three-dimensional space, and the ratio of the graph and the axis is different from that of a normal three-dimensional space, being D:P:H=1 / 2:1:1. Therefore, in the formula representing the sphere, a coefficient 2 is added to the axis ratio of the dispersion force δD term based on the Hansen sphere method. The selection area of ​​the release agent will be explained in more detail below using formulas.

[0041] Figure 2 is a conceptual diagram of the region assumed in the HSP three-dimensional coordinate space when selecting a stripping agent. In Figure 2, B and C represent the coordinates B and C, respectively, and the assumed region is shown by a virtual line. Ra is the radius of a cylinder with the line segment BC as its central axis, and the star marks represent substances with coordinates around the cylinder. Here, the coordinate E on the line segment BC 0 can be expressed by the following formula (a). (δDE 0 , δPE 0 , δH 0 ) = (δDB, δPB, δHB) + t 1 {(δDC - δDB), (δPC - δPB), (δHC - δHB)} (a) In formula (a), 0≦t 1 ≦1. Here, based on the Hansen sphere method, the coordinate E 0 with a radius of R a The coordinates on the surface of the sphere or inside the sphere can be expressed by the following equation (b). Ra^2≧4(δDE 0 -δDE)^2+(δPE 0 -δPE)^2+(δHE 0 -δHE)^2 (b) In formula (a), t 1Since varies from 0 to 1, the area in which the coordinate E of the release agent can be selected is represented by the locus of a sphere with a radius Ra.

[0042] At coordinate n (δDn, δPn, δHn) in the region, E 0 If the distance from the target point is R(n), then R(n) / Ra=RED (relative energy difference), and the coordinate n is selected so that RED is 1 or less. For Ra, the value used in formula (I) in the fourth step can be adopted. When there are multiple candidate substances for the coordinate E of the stripping agent that satisfies the above formula (b), t 1 It is preferable to select a material with R(n) close to 0.5 and R(n) close to 0. 1 Even if the values ​​of R(n) and R(n) satisfy the conditions, a specific substance may be excluded from selection from the viewpoint of cost or safety of the selected substance.

[0043] Next, we will explain the specific selection procedure. 1 The coordinates of the release agent where E = 0.5 are the recommended coordinates, and the E 0 Next, the sphere is searched for based on the following formula (c). R(n)^2=4(δDE 0 -δDn)^2+(δPE 0 -δPn)^2+(δHE 0 -δHn)^2 (c) By comparing with the database values, extract the substance with coordinate n where RED is 1 or less. If there are multiple applicable substances, select the substance with the smaller RED value as the coordinate E of the stripping agent. If there is no applicable substance with coordinate n where RED is 1 or less, t 1 The value of t 1 = 0.5 ± Δ, and E 0is calculated, and the substance having the coordinate n is extracted based on formula (c) in the same manner as above. That is, a sphere having a center shifted by Δ toward the coordinate B side from the recommended coordinate, and a sphere having a center shifted by Δ toward the coordinate C side are searched, respectively. Δ can be set to, for example, 0.05, but is not limited to a specific value. If no corresponding substance is found, this operation is repeated, and finally, a region whose center is on the line segment connecting B and C and represented by the locus of a sphere with a radius of Ra can be searched. In addition, when selecting a stripping agent, a mixed stripping agent containing two or more substances can be selected based on the above-mentioned method for calculating the HSP coordinates of the mixture.

[0044] In formula (II), in general, for example, when the base material is a metal, the coordinates of the release agent can be selected so as to satisfy the relationship in the above formula, and when the base material is glass, the coordinates can be selected so as to satisfy the relationship in the following formula.

[0045] The fifth step can be carried out once the coordinates B and C of the second and third steps are determined, and can be carried out independently in any order, regardless of the first and fourth steps.

[0046] (6) A step of selecting an inducer having HSP coordinate F. The sixth step is a step of selecting an inducer having an HSP coordinate F based on the positional relationship between the coordinate D and coordinate E. The inducer is selected from substances that have a high affinity to both the penetrant and the stripping agent. Specifically, when the coordinate F of the inducer is (δDF, δPF, δHF) and the interaction radius is Ra, the inducer is selected from substances that have coordinate F within a region represented by the locus of a sphere whose center is on the line segment DE and whose radius is Ra, in relation to the coordinate D obtained in the fourth step and the coordinate E obtained in the fifth step, and that satisfy the condition of the following formula (III). (δDD, δPD, δHD) ≦(δDF, δPF, δHF) ≦(δDE, δPE, δHE) or (δDD, δPD, δHD) > (δDF, δPF, δHF) > (δDE, δPE, δHE) (III)

[0047] The step of selecting the coordinate F that satisfies the above conditions and formula (III) is substantially the same as the fifth step. It will be further explained with reference to FIG. 1. In FIG. 1, D represents the HSP coordinate of the penetrant, and E represents the HSP coordinate of the stripping agent. In this case, the coordinate F is selected from a region whose center is on the line segment connecting D and E and is represented by the locus of a sphere with a radius of Ra. In other words, the coordinate F is selected from the surface and inside of a region in which a hemisphere with a radius of Ra is added to the two bases of a cylinder with a radius of Ra and the central axis is the line segment DE.

[0048] In this step, a selection area can be assumed in the HSP three-dimensional coordinate space in the same manner as in FIG. 2 (not shown). Here, the coordinates F of a point on the line segment DE are 0 can be expressed by the following formula (d). (δDF 0 , δPF 0 , δH 0 ) = (δDD, δPD, δHD) + t 2 {(δDE -δDD), (δPE - δPD), (δHE -δHD)} (d) In formula (d), 0≦t 2 ≦1. Here, based on the Hansen sphere method, the coordinate F 0 with a radius of R a The coordinate F on the surface of the sphere or inside the sphere can be expressed by the following equation (e). Ra^2≧4(δDF 0 -δDF)^2+(δPF 0 -δPF)^2+(δHF 0 -δHF)^2 (e) In formula (d), t 2 Since varies from 0 to 1, the region in which the coordinate F of the inducer can be selected is represented by the locus of a sphere with radius Ra.

[0049] As in the fifth step, at coordinate n (δDn, δPn, δHn) in the region, F 0 If the distance from is R(n), the coordinate n is selected such that RED is 1 or less. For Ra, the value used in formula (I) can be adopted. When there are multiple candidate substances as the coordinate F of the inducer that satisfies the above formula (d), t2 It is preferable to select a substance with t close to 0.5 and R(n) close to 0. The inducer also has t 2 It is possible to select the material taking into consideration not only the value of R(n) but also the cost and safety of the material.

[0050] The specific selection procedure is substantially the same as in the fifth step. 2 The coordinates of the inducer where F = 0.5 are the recommended coordinates, and the F 0 Next, the sphere is searched for based on the following formula (f). R(n)^2=4(δDF 0 -δDn)^2+(δPF 0 -δPn)^2+(δHF 0 -δHn)^2 (f) The coordinate extraction method can be performed in the same manner as in step 5. If there is no corresponding substance with coordinate n where RED is 1 or less, t 2 For = 0.5 ± ΔF 0 Then, the substance having the coordinate n can be extracted based on the formula (f). Furthermore, when selecting an inducer, it is also possible to select a mixed inducer that is a mixture of two or more substances.

[0051] In this way, by carrying out steps 1 to 6, three types of chemicals, a penetrating agent, a stripping agent, and an inducer, can be selected, and using these, efficient removal of scale is possible.

[0052] [Second embodiment: Method for producing scale removal agent] According to a second embodiment, the present invention relates to a method for producing a scale removing agent, the method including the following steps: (a) A step of selecting a descaling agent including a penetrating agent, an inducing agent, and a stripping agent. (b) preparing a penetrating agent, an inducing agent, and a stripping agent separately, or preparing a drug comprising a combination of two or more of the penetrating agent, the inducing agent, and the stripping agent;

[0053] Step (a) according to this embodiment corresponds to the selection method according to the first embodiment. Therefore, step (a) can be performed by carrying out steps 1 to 6 of the first embodiment.

[0054] In step (b) of this embodiment, the substances selected in step (a) are prepared for use. When the penetrant, inducer, and stripper are all compounds or mixtures and are used separately without being mixed, the penetrant, inducer, and stripper can be prepared separately and packaged separately. In this case, the scale removal agent is a combination of multiple agents and can be handled as a combination agent or agent kit.

[0055] When the penetrating agent, inducer, and release agent are all compounds or mixtures whose HSP coordinates are very close to each other, or when any two or more of them are the same substance, step (b) may be a step of mixing them and packaging them.

[0056] When any of the penetrating agent, the inducing agent, and the stripping agent is a monomer or a modifying group, step (b) may be a step of preparing a copolymer thereof, or a single compound having a modifying group.

[0057] According to the method for producing a scale removing agent of the second embodiment, an agent or a combination of agents in a suitable form can be produced depending on the properties and method of use of the penetrating agent, inducer, and stripping agent.

[0058] [Third embodiment: scale removal method] According to a third embodiment, the present invention relates to a method for removing scale. The method for removing scale includes the following steps. (I) selecting a penetrating agent, a guide agent, and a stripping agent based on the selection method of the first embodiment; (II) applying the penetrant, inducer, and stripper selected in the selecting step to the target scale in that order or substantially simultaneously;

[0059] As an optional step, the method may further include either or both of the following steps (III) and (IV). (III) applying a physical force to the target scale. (IV) applying a corrosion inhibitor to the target scale.

[0060] Step (I) in this embodiment can be carried out by the method described in the first embodiment, and therefore a description thereof will be omitted here.

[0061] In step (II), the penetrating agent, the inducer, and the stripping agent selected in step (I) are prepared. The penetrating agent, the inducer, and the stripping agent can be prepared by the method described in step (b) of the second embodiment.

[0062] When separate agents are used as the penetrating agent, the inducing agent, and the stripping agent, they are applied to the target scale in this order. The target scale may be a scale that is presumed to be the composition used to determine the coordinate A in the first embodiment.

[0063] Examples of the application method of each agent include, but are not limited to, a process of spraying each agent onto the target scale, a process of pouring each agent onto the equipment to which the target scale is attached, a process of contacting each agent with the target scale for a predetermined period of time, a process of spraying each agent onto the target scale, and a process of injecting each agent onto the target scale. Examples of the process of pouring each agent onto the equipment to which the target scale is attached include a method of filling the equipment with the agent and circulating the agent, a method of pouring the agent over the equipment with the equipment half open, and a method of injecting the agent with residual liquid. Examples of the process of contacting the agent include a method of immersing the equipment or a part thereof in the agent. Examples of the process of injecting each agent onto the target scale include a method of dripping the agent onto the scale.

[0064] The function of each agent and the mechanism of scale removal will be described with reference to FIG. 3. FIG. 3(a) is a schematic diagram of the first stage of the removal method, in which a penetrant D is applied to a scale 3 fixed on a base material 1. The penetrant D functions to penetrate the entire scale 3 and generate cracks. (b) is a schematic diagram of the second stage of the removal method, in which an inducer F is applied after the application of the penetrant D. The inducer F is preferably applied after a predetermined time has elapsed after the application of the penetrant D, and can be applied after 1 to 3 hours, but is not limited to a specific time. The inducer F promotes the development of the cracks generated by the penetrant D, and reaches the base material side surface 2 of the scale (the interface between the scale and the base material). (c) is a schematic diagram of the third stage of the removal method, in which a stripper E is applied after the application of the inducer F. The stripper E is preferably applied after a predetermined time has elapsed after the application of the inducer F, and can be applied after 0.5 to 2 hours, but is not limited to a specific time. The remover E acts directly on the base material side surface 2 of the scale, and because it has a high affinity with the base material 3, it reaches the base material 3. (d) is the fourth stage of the removal method, where the scale that was adhered together is decomposed by the cooperative action of the penetrant D, inducer F and remover E, and is peeled off from the surface of the base material 3, becoming small scale pieces 31, 32.

[0065] In another embodiment, when the penetrant, inducer, and stripper are prepared as a mixture, copolymer, or single compound, they can be applied to the scale substantially simultaneously, which may be advantageous because it reduces the labor of managing each agent individually and the cumbersome steps of applying each agent individually, and allows the target scale to be removed in a single step.

[0066] Step (III), which is an optional step, is a step of carrying out a method in which a physical force acts on the scale, and can be used in combination with the use of a penetrant, an inducer, and a stripping agent. In terms of time sequence, the physical method may be carried out before the application of the penetrant, or after the application of the stripping agent. Alternatively, the physical force can be applied substantially simultaneously during the use of any or all of the penetrant, inducer, and stripping agent. Preferably, the physical method can be carried out after the stripping agent is applied to the target scale.

[0067] An example of a specific physical method is a step of applying a temperature change to the target scale to generate a shear force. In this step, a temperature change is applied to the base material and the scale, and a shear force caused by the difference in linear expansion coefficient accompanying the temperature change causes cracks or fissures in the scale, making it easier to peel off. For example, a step of heating the scale and its surrounding members and a step of cooling the scale can be performed. Heating and cooling can be performed repeatedly. These operations are advantageous in that a temperature difference is applied to the scale and its surrounding members, and preferably the temperature difference is increased, thereby maximizing the thermal stress that is generated. For the heating step, one or more means selected from a heater, induction heating (IH), microwaves, burners, boiler steam, and hot air can be used. For the cooling step, one or more means selected from a chiller, river water, dry mist, and cold air can be used.

[0068] Another example of a specific physical method is a step of applying a mechanical force to the target scale. In this step, a tool or the like can be used to perform mechanical operations such as polishing, cutting, peeling, drilling, striking (jet cleaning or sandblasting), vibrating (vibrator or ultrasonic wave), cutting, peeling, and / or crushing on the target scale. A plurality of different physical methods can also be used in combination, and the physical method is not limited to the exemplified methods.

[0069] Step (IV), which is an optional step, is a step of applying a corrosion inhibitor to the target scale. The corrosion inhibitor is a chemical added mainly to prevent oxidation (rust generation) of the metal surface due to contact with oxygen, and may be a commercially available chemical. For example, a corrosion inhibitor such as a coating agent such as a silicate-based, phosphate-based, amine-based, or oxidizing agent-based corrosion inhibitor, or an oxygen absorber such as an organic substance based on iron powder or L-ascorbic acid (vitamin C) can be used. Chronologically, the corrosion inhibitor can be applied at any time during the removal method, and is more preferably applied after the completion of cleaning.

[0070] According to the scale removal method of this embodiment, by applying a combination of a penetrant, an inducer, and a stripper selected according to the target scale in a predetermined order, it is possible to reduce the adhesion of the scale and remove the scale effectively, economically, and safely. Conventional scale removal using oxidizing agents or alkaline agents generates harmful gases and is a dangerous operation, but in the present invention, scale removal is performed using a dissolution reaction that does not substantially involve a chemical reaction, making the operation safer.

[0071] [Fourth embodiment: Scale removal method for geothermal power generation system] According to a fourth embodiment, the present invention relates to a method for removing scale from a geothermal power generation system. The method for removing scale from a geothermal power generation system includes the following steps. (i) A step of selecting a penetrating agent, a guide agent, and a stripping agent for each of a plurality of devices constituting a geothermal power generation system based on the selection method of the first embodiment. (ii) applying the penetrant, inducer, and stripper selected in the selecting step to the target scale in this order or substantially simultaneously for each of the plurality of devices;

[0072] The selection in step (i) can be performed by the method described in the first embodiment. The multiple devices constituting the geothermal power generation system are not particularly limited and may be any devices in the system for which scaling is a concern or problem. The specific method and chronological order of application of the penetrant, inducer, and stripper in step (ii), the optional step of applying a physical force to the target scale, and the step of applying a corrosion inhibitor to the target scale can be performed by the method described in the third embodiment.

[0073] A plurality of devices constituting the geothermal power generation system in step (i) will be described with reference to FIG. 4. FIG. 4 is a conceptual flow diagram showing an example of a binary cycle type geothermal power generation system. The geothermal power generation system can be composed of a production well 11, a first steam separator 12, a first turbine / generator 13, a hot water tank 14, a second steam separator 15, an evaporator 16, a separator 17, a second turbine / generator 18, a feed heater 19, an air-cooled condenser 20, a preheater 21, a flash tank 22, a hot water pit 23, a reduction pump 24, and a reduction well 25. Optionally, a facility 26 for downstream heat utilization may be included. In FIG. 4, the flow of geothermal water is indicated by solid arrows, and the flow of the low boiling point medium is indicated by dashed arrows. The area surrounded by dashed lines indicates the flash power generation area.

[0074] The flow of materials in a geothermal power generation system will be briefly described. The production well 11 is a well that delivers hot water, steam, or a mixture thereof (geothermal water) from a geothermal reservoir underground to the surface. The geothermal water delivered from the production well 11 is separated into steam, which is a gas component, and hot water, which is a liquid component, in the first steam separator 12. The separated steam is delivered to the first turbine-generator 13, where it is used to rotate the turbine and generate electricity in the generator. The steam that has passed through the first turbine-generator 13 is cooled in a condenser (not shown) and delivered to the reinjection well 25 through a pipe (not shown). Meanwhile, the hot water separated in the first steam separator 12 is delivered to the second steam separator 15 via the hot water tank 14. The gas component separated in the second steam separator 15 is delivered to the evaporator 16, where it is used to heat a low boiling point solvent. The hot water reliquefied by heating the low boiling point solvent is then guided to a flash tank 22. The liquid component separated in the second brackish water separator 15 is guided to a preheater 21 to heat the low boiling point medium, and then guided to the flash tank 22. In the flash tank 22, the hot water is depressurized, and the generated water vapor is dissipated into the atmosphere. The liquid component remaining after depressurization is guided to a hot water pit 23, and a portion is returned to a reinjection well 25 by a reinjection pump 24, and a portion is guided to a facility 26 for downstream heat utilization, such as a hot spring facility.

[0075] Meanwhile, the low boiling point medium circulates within the facility as indicated by the dashed arrows. The low boiling point medium is heated by geothermal steam in the evaporator 16, and the two-phase flow of the low boiling point medium is separated into gas and liquid phases in the separator 17. The gas phase low boiling point medium is led to the second turbine / generator 18. The low boiling point medium used to rotate the second turbine / generator 18 is condensed and liquefied in the feed heater 19, has heat released in the condenser 20, and is led to the preheater 21. In the preheater 21, the liquefied low boiling point medium is heated again by geothermal water and circulated to the evaporator 16.

[0076] In selecting the scale removing agent in this embodiment, non-limiting examples of the adhesion site of the target scale are shown by arrows in FIG. 1. For example, the following may be mentioned: equipment at or near the position of arrow a immediately after the production well 11 is blown out; equipment at or near the position of arrow b going through the first steam separator 12 to the second steam separator 15; equipment at or near the position of arrow c going through the second steam separator 15 to the preheater 21; equipment at or near the position of arrow d going from the hot water pit 23 to the reduction pump 24; or equipment at or near the position of arrow e sent by the reduction pump 24 to the facility 26 for subsequent heat utilization. The equipment may include piping, valves, measuring instruments, tanks, heat exchangers, or any other equipment. Even within the same geothermal power generation system, the amount and composition of the scale that adheres to these parts may differ depending on the composition and temperature of the fluid in contact, the piping material, etc. Therefore, by determining the coordinates A, B, and C for each device and obtaining the optimal combination of penetrant, inducer, and stripping agent, it is possible to achieve the optimal scale removal method tailored to that device.

[0077] The scale removal method according to this embodiment can typically be performed when the geothermal power generation system is stopped, for example, during regular inspection of the geothermal power generation system. Alternatively, the scale removal method can also be performed when the dirt tolerance set for each piece of equipment such as the turbine constituting the geothermal power generation system is exceeded. Details of the removal method are as described in the third embodiment above, and the method can be performed by immersing the equipment in a chemical agent or spraying the chemical agent on the equipment.

[0078] The geothermal power generation system in which the method for inhibiting scale adhesion according to this embodiment is implemented is not limited to the binary cycle type geothermal power generation system shown in the figure, and can be applied to any geothermal power generation system.

[0079] According to the scale removal method of this embodiment, a combination of penetrating agent, inducer, and stripping agent selected according to the base material of the equipment that makes up the geothermal power generation system and the target scale is used, and the optimal agent can be selected not only in relation to the scale that is generated but also to the base material to which the scale adheres, making it possible to remove the adhered scale effectively, economically, and safely. EXAMPLES

[0080] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0081] In a model plant for a geothermal power generation system, the HSP coordinate A of the entire target scale, the HSP coordinate B of the base material side surface of the target scale, and the HSP coordinate C of the target base material were obtained according to the first to third steps of the first embodiment. The coordinates are shown in Table 1. Next, according to the fourth step, the calculation of formula (I) was performed with Ra=5 based on the HSP coordinate A below, and a corresponding compound was searched for using a database. As a result, acetone, which has the HSP coordinate D below, was selected as the penetrating agent. According to the fifth step, t 1 = 0.5, i.e., the recommended coordinates of the stripping agent that are the midpoint between HSP coordinates B and C were calculated. Based on the recommended coordinates, a search was made using the database to find a compound that satisfies the conditions for the stripping agent in the fifth step with Ra = 5. As a result, 2-(furan-2-ylmethyldisulfanylmethyl)furan, which has the following HSP coordinate E, was selected as the stripping agent in the sixth step. 2 = 0.5, that is, the recommended coordinates of the inducer that is the midpoint between HSP coordinates D and E were calculated. Based on this, a search was conducted using the database to find a compound that satisfies the conditions for the inducer in the sixth step with Ra = 5. As a result, dichloromethane, which has the following HSP coordinate F, was selected as the inducer.

[0082] [Table 1] [Industrial Applicability]

[0083] The method for selecting a scale removing agent and the scale removing method according to the present invention can be applied to the removal of scale from various plant systems, particularly from geothermal power generation systems. [Explanation of symbols]

[0084] A HSP coordinates of the entire target scale, B HSP coordinates of the base metal surface of the target scale C HSP coordinates of the target base material, D penetrant, E stripping agent, F inducer 1 Base material, 2 Base material surface of scale, 3 Scale, 31, 32 Scale strips

Claims

1. A step of obtaining a coordinate A of an intrinsic physical property value based on the Hansen solubility parameters of the entire target scale; A step of obtaining coordinates B of intrinsic physical property values ​​based on the Hansen solubility parameters of the surface of the target scale on the base material side; A step of obtaining a coordinate C of an intrinsic property value based on the Hansen solubility parameter of the target base material; A step of selecting a penetrant having a coordinate D of an intrinsic physical property value based on the Hansen solubility parameters based on an interaction radius Ra of the target scale centered on the coordinate A; A step of selecting a stripping agent having a coordinate E of an intrinsic physical property value based on the Hansen solubility parameters based on the positional relationship between the coordinate B and the coordinate C; A step of selecting an inducer having a coordinate F of an intrinsic physical property value based on the Hansen solubility parameters based on the positional relationship between the coordinate D and the coordinate E; A method for selecting a scale removal agent, comprising:

2. The coordinates of the intrinsic physical property values ​​are expressed in three-dimensional coordinates consisting of a dispersion force δD, a dipole-dipole force δP, and a hydrogen bond force δH, The coordinate A is (δDA, δPA, δHA), The coordinate D is (δDD, δPD, δHD), If the interaction radius is Ra, The step of selecting a penetrant comprises: The following formula (I): 4(δDA-δDD)^2+(δPA-δPD)^2+(δHA-δHD)^2 ≦ (Ra)^2 (I) The selection method according to claim 1, wherein a substance having a coordinate D satisfying the following formula is selected as the penetrant.

3. The coordinate B is (δDB, δPB, δHB), The coordinate C is (δDC, δPC, δHC), The coordinate E is (δDE, δPE, δHE), If the interaction radius is Ra, The step of selecting the release agent is based on the Hansen sphere method, and is performed by determining whether the release agent is a coordinate E within a region represented by a locus of a sphere having a center on a line segment BC and a radius Ra, and the coordinate E is expressed by the following formula (II): (δDB, δPB, δHB) ≦ (δDE, δPE, δHE) ≦ (δDC, δPC, δHC) or (δDB, δPB, δHB) > (δDE, δPE, δHE) > (δDC, δPC, δHC) (II) The method according to claim 1 or 2, wherein a substance having a coordinate E that satisfies the following formula is selected as the release agent.

4. The coordinate F is (δDF, δPF, δHF), If the interaction radius is Ra, The step of selecting the inducer is based on the Hansen sphere method, and is performed by determining whether the inducer is a coordinate F within a region represented by a locus of a sphere having a center on a line segment DE and a radius Ra, and the coordinate F is expressed by the following formula (III): (δDD, δPD, δHD) ≦ (δDF, δPF, δHF) ≦ (δDE, δPE, δHE) or (δDD, δPD, δHD) > (δDF, δPF, δHF) > (δDE, δPE, δHE) (III) The selection method according to claim 3, wherein a substance having a coordinate F that satisfies the following formula is selected as an inducer.

5. Selecting a penetrating agent, a guide agent, and a stripping agent based on the selection method of claim 1; applying the penetrant, inducer, and stripper selected in the selecting step to the target scale in that order or substantially simultaneously; A method for removing scale comprising:

6. The method for removing scales according to claim 5, further comprising the step of applying a physical force to the target scale and / or the step of applying a corrosion inhibitor to the target scale.

7. 1. A method for removing scale from a geothermal power generation system, comprising: A step of selecting a penetrating agent, a guide agent, and a stripping agent for each of a plurality of devices constituting a geothermal power generation system based on the selection method described in claim 1; applying the penetrant, inducer, and stripper selected in the selecting step to the target scale in this order or substantially simultaneously for each of the plurality of devices; A method for removing scale comprising:

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