How to select a scale dispersant

Abstract

A method for selecting a scale dispersant that conforms to characteristics of water being treated and generated scale. A method for selecting a scale dispersant, the method including a step for obtaining coordinates Cs of inherent physical property values based on Hansen solubility for scale being treated, a step for obtaining coordinates Cw of inherent physical property values based on Hansen solubility for water being treated, and a step for selecting a scale dispersant on the basis of the positional relationship between the coordinates Cs of the inherent physical property values for the scale being treated and the coordinates Cw of the inherent physical property values for the water being treated.

Description

[Technical Field]

[0001] The present invention relates to a method for selecting a scale dispersant. [Background technology]

[0002] BACKGROUND ART Conventionally, scale deposition has been a problem in systems that include fluid distribution systems, such as power plant systems, ship systems, boiler systems, and steel plant systems.

[0003] It is known that certain chemicals can be used to dissolve and remove scale that has already formed. Conventionally, in plant systems, such chemicals have been used based on empirical data, such as oxidizing agents such as hydrofluoric acid, acetic acid, sulfuric acid, and hydrochloric acid, and alkaline agents such as sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0004] For example, in geothermal power plants, a method is known in which an alkaline agent is injected to suppress silica precipitation in fluids with high calcium and dissolved silica concentrations without precipitating calcium silicate hydrate (CSH) (see, for example, Patent Document 1). Also known as a chemical is a scale inhibitor that contains an amidated (poly)alkylene polyamine or a derivative thereof (A) and a quaternary ammonium salt of an anionic group-containing polymer (B) with a degree of neutralization of 30 to 100 mol %, and has a water content of 10 to 80 mass % (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-196197 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-46679 Summary of the Invention [Problem to be solved by the invention]

[0006] Among various plant systems where scale deposition is a problem, in geothermal power plants, the high dissolved silica concentration makes it particularly susceptible to the deposition of scale such as amorphous silica, which is a particular problem. For example, while the silica concentration in cooling water at a typical plant is at most 150 ppm, the silica concentration in geothermal water distributed at geothermal power plants in Japan is approximately 450 to 900 ppm.

[0007] Furthermore, the silica-based scale components in geothermal power plants vary depending on the dissolved metal components contained in the geothermal water. As a result, different silica-based scale forms in different geothermal power plants. Therefore, it has been difficult to select the optimal chemical to suppress scale for each plant. In the past, known chemicals based on experience have been used, but the optimal chemical selection has not been implemented, which has led to unexpected deposits and other problems.

[0008] When silica-based scale precipitates, periodic overhaul inspections of turbines, steam separators, heat exchangers, and other components of geothermal power plants become necessary. Removing the scale requires the use of cleaning agents such as hydrofluoric acid, and the removed scale becomes industrial waste, increasing costs. Therefore, technology is needed to select the optimal anti-scale agents for geothermal power plants. [Means for solving the problem]

[0009] The inventors have considered using Hansen solubility parameter (HSP) technology to select chemicals appropriate for the properties of fluids containing scale-causing substances, such as geothermal water. In particular, they have come up with the idea of ​​selecting chemicals that can also accommodate differences in dissolved silica concentration, dissolved metal species, and concentrations, which vary from one geothermal power plant to another, based on the HSP coordinates between scale components and fluids containing scale-causing substances, and have completed the present invention.

[0010] According to one embodiment, the present invention provides a method for selecting a scale dispersant, which comprises: determining the coordinate C of the intrinsic physical property based on the Hansen solubility for the target scale; s and a process of obtaining the coordinate C of the intrinsic physical property value based on the Hansen solubility for the target water. w and a step of obtaining the coordinates C of the characteristic physical property values ​​of the target scale. s and the coordinates of the specific physical properties of the target water, C w and selecting a scale dispersant based on the positional relationship between the scale dispersant and the scale dispersant.

[0011] In the method for selecting a scale dispersant, the intrinsic physical property value is expressed by three-dimensional coordinates consisting of a dispersion force δD, a dipole-dipole force δP, and a hydrogen bonding force δH, and the coordinates C of the target scale s (δD s , δP s , δH s ), the coordinates of the target water C w (δD w , δP w , δH w ), coordinate C of the scale dispersant to be selected a (δD a , δP a , δH a ), the coordinates C of the characteristic physical property values ​​of the target scale s and the coordinates C of the specific physical properties of the target water w Distance R a When the scale dispersant is selected, The following formula (1): 4(δD a -δD w ) 2 +(δP a -δP w ) 2 +(δH a -δH w ) 2 ≦(R a ) 2 (1) The coordinate C satisfies a It is preferable to select a substance having the following structure as the scale dispersant.

[0012] In the method for selecting a scale dispersant, the intrinsic physical property value is expressed in two-dimensional coordinates consisting of a dispersion force δD and a dipole-dipole force δP, and the coordinates C of the target scale s (δD s , δP s ), the coordinates of the target water C w (δD w , δP w ), coordinate C of the scale dispersant to be selected a (δD a , δP a ), the step of selecting the scale dispersant is s ≧δP w In the case of δP a ≦δP w The coordinate C satisfies a (ii) a substance having δP is selected as a scale dispersant; s ≦δP w In the case of δP a ≧δP w The coordinate C satisfies a It is preferable to select a substance having the following structure as the scale dispersant.

[0013] In the method for selecting a scale dispersant, (ia) δP s ≧δP w and δD s ≧δD w In the case of δP a ≦δP w and δD a ≦δD w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant: (ib)δP s ≧δP w and δD s ≦δD w In the case of δP a ≦δP w and δD a ≧δD w The coordinate C satisfies a A substance having the following structure is selected as a scale dispersant: (iia)δP s ≦δP w and δD s ≦δD w In the case of δPa ≧δP w and δD a ≧δD w The coordinate C satisfies a A substance having the following structure is selected as a scale dispersant: (iib)δP s ≦δP w and δD s ≧δD w In the case of δP a ≧δP w and δD a ≦δD w The coordinate C satisfies a It is preferable to select a substance having the following structure as the scale dispersant.

[0014] In the method for selecting a scale dispersant, the intrinsic physical property value is expressed in two-dimensional coordinates consisting of a dispersion force δD and a dipole-dipole force δP, and the coordinates C of the target scale s (δD s , δP s ), the coordinates of the target water C w (δD w , δP w ), the coordinate C of the scale dispersant or its modifying group to be selected a (δD a , δP a ), coordinate C w and coordinate C s The distance between a When the scale dispersant is selected, the step of selecting the scale dispersant is a If is less than 9.5, δD a But (δD w -0.5)~(δD w +4.5) and δP a But (δP w -10)~(δP w +8) a (2) R a If is greater than 9.5, δD a (δD w +0.5)~(δD w +4.5) and δP a But (δP w -10)~(δP w+8) a It is preferable to select a substance having the following structure as the scale dispersant.

[0015] In the method for selecting a scale dispersant, the target water is preferably selected from tap water, sewage, well water, seawater, fresh water, river water, pure water, geothermal water, industrial water, and factory wastewater.

[0016] In the method for selecting a scale dispersant, it is preferable that the scale dispersant is selected from allylamine, diallylamine, maleic acid, ascorbic acid, nicotinic acid, acrylic acid, dimethyldiallylammonium chloride, difurfuryl disulfide, sulfur dioxide, or a polymer containing one or more of these as a monomer.

[0017] In the method for selecting a scale dispersant, the scale dispersant preferably contains a chelating agent.

[0018] According to another embodiment, the present invention relates to a method for producing a scale dispersant, the method comprising the steps of selecting a scale dispersant or a modifying group having predetermined coordinates based on any of the methods for selecting a scale dispersant described above, and preparing a scale dispersant based on the selected scale dispersant or modifying group.

[0019] According to yet another embodiment, the present invention relates to a method for inhibiting scale deposition in a geothermal power generation system, (I) a step of selecting a scale dispersant by any of the methods for selecting a scale dispersant described above; (II) adding the selected scale dispersant to the geothermal water of the geothermal power generation system; Including, In the selection process, the coordinates C of the intrinsic physical property values ​​of the geothermal water w The present invention relates to a method comprising the step of obtaining

[0020] In the method for inhibiting scale adhesion, the coordinates C of the intrinsic physical properties of geothermal water derived from two or more different production wells are wand preferably includes a step of selecting a scale dispersant corresponding to the geothermal water derived from each production well. [Effects of the Invention]

[0021] The method for selecting a scale dispersant according to the present invention makes it possible to select a suitable scale dispersant that corresponds to the target water and the target scale components. By using a dispersant selected by the method for selecting a scale dispersant according to the present invention, it is possible to suppress the precipitation and growth of scale, shorten the plant maintenance cycle, and reduce industrial waste caused by scale. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating an example of a method for selecting a dispersant according to the first aspect of the first embodiment of the present invention, and is a diagram illustrating a method for selecting intrinsic physical property values ​​on three-dimensional coordinates based on the Hansen solubility. [Figure 2] FIG. 2 is a diagram illustrating an example of a method for selecting a dispersant according to the second aspect of the first embodiment of the present invention, and is a diagram illustrating a selection method that does not depend on the δH axis of the intrinsic physical property value based on the Hansen solubility. [Figure 3] Figure 3 is a diagram of the three-dimensional coordinate system shown in Figure 2 projected onto a two-dimensional coordinate system consisting of the δD axis and the δP axis, and explains the first quadrant Q1, second quadrant Q2, third quadrant Q3, and fourth quadrant Q4 when the δDw axis and the δPw axis are set based on the coordinates of the target water. [Figure 4] FIG. 4 is a diagram for explaining an example of a method for selecting a scale dispersant according to the third aspect of the first embodiment of the present invention, and is a diagram showing the preferred ranges of the intrinsic physical property values ​​δDa and δPa based on the Hansen solubility of a substance suitable as a dispersant for scale that has good affinity with the target water. [Figure 5]FIG. 5 is a diagram for explaining an example of a method for selecting a scale dispersant according to the third aspect of the first embodiment of the present invention, and is a diagram showing the preferred ranges of the intrinsic physical property values ​​δDa and δPa based on the Hansen solubility of a substance suitable as a dispersant for scale that has poor affinity with the target water. [Figure 6] FIG. 6 is a diagram conceptually illustrating an example of a geothermal power generation system to which a method for inhibiting scale adhesion according to a third embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments described below.

[0024] [First embodiment: Method for selecting a scale dispersant] According to a first embodiment, the present invention relates to a method for selecting a scale dispersant. The selection method includes the following steps. (a) For the target scale, the coordinate C of the intrinsic physical property value based on the Hansen solubility s The process of obtaining (b) Coordinate C of the intrinsic physical property value based on the Hansen solubility for the target water w The process of obtaining (c) the coordinate C of the characteristic property value of the target scale s and the coordinates of the specific physical properties of the target water, C w A process of selecting a scale dispersant based on the positional relationship with

[0025] In the present invention, a scale dispersant is a substance that can be added to target water to inhibit the precipitation of scale precursors and / or inhibit the adhesion of new scale precursors to already formed scale, thereby reducing the amount of scale formation compared to when the scale dispersant is not used. The scale dispersant may be a low molecular weight compound or a high molecular weight compound. Furthermore, the scale dispersant may be composed of a single substance or a mixture of two or more substances. In this specification, the term scale dispersant may be omitted and simply referred to as a dispersant.

[0026] In the present invention, the target scale refers to scale on which a scale dispersant acts and whose adhesion is inhibited. The target scale may be any scale that may contain inorganic and organic compounds. More specifically, the target scale may be scale that is generated and adheres due to substances dissolved in the flowing fluid in power plant systems such as geothermal, thermal, nuclear, hydroelectric, or biomass power plants; ship systems such as marine exhaust gas cleaning systems (EGCS) and seawater desalination systems; boiler systems for factory heating sources and building heating and hot water supply systems; cooling water systems; and steel plant systems such as cleaning water systems. The type of target scale is not particularly limited. For example, in geothermal power plants, the target scale may be multi-component scale that forms in layers on substrates such as piping, heat exchangers, turbines, and drains that constitute the plant. An example of the target scale is silica-based scale.

[0027] In the present invention, the target water is a fluid containing a scale precursor and may be any aqueous fluid for which scale formation is a concern, including, but not limited to, tap water, sewage water, well water, seawater, fresh water, river water, pure water, geothermal water, industrial water, and factory wastewater.

[0028] The intrinsic physical property values ​​based on the Hansen solubility index may be dispersion force δD, dipole-dipole force δP, and hydrogen bonding force δH. In a first aspect of this embodiment, a selection method based on a three-dimensional coordinate space consisting of three intrinsic physical property values ​​may be used. The three-dimensional coordinates are preferably orthogonal three-dimensional coordinates. In a second or third aspect of this embodiment, a selection method based on a two-dimensional coordinate space consisting of two intrinsic physical property values, dispersion force δD and dipole-dipole force δP, may be used.

[0029] In step (a), the coordinates of the characteristic physical property values ​​based on the Hansen solubility are obtained for the target scale. s (δD s , δP s , δHs ) can generally be obtained by experimentation. For example, this involves steps of collecting target scale at a desired location in a target plant, analyzing the layer structure and components of the scale, and experimentally obtaining coordinates of characteristic physical property values ​​from the components.

[0030] Coordinate C of the characteristic physical property value of the target scale s can also be estimated from the composition ratio of components in the target water. This is useful when it is difficult to stop the operation of the plant system through which the target water flows, or when it is impossible to collect scale because it is severely adhered and therefore impossible to remove, or when it is necessary to obtain the scale composition simply. Since the composition of the target water flowing within the plant system varies depending on the location of the plant system, the target water can be collected at any desired location. For example, in a geothermal power plant, geothermal water flowing through production wells, reinjection wells, heat exchangers, etc. can be collected to determine the coordinates of the characteristic physical properties of the target scale.

[0031] The collected target water can be analyzed by any analytical method. The analytical method can be based on trace element analysis. For example, element analysis can be performed by a method using inductively coupled plasma (ICP-MS), more specifically, ICP-MS analysis can be used, but the method is not limited to a specific one.

[0032] The process of experimentally obtaining the coordinates of the intrinsic physical properties from actually collected scale components or from the results of elemental analysis of the target water can be carried out, for example, by the penetration rate method, in which a solvent is allowed to penetrate into the scale particles and the affinity is evaluated.

[0033] In step (b), similarly to step (a), the coordinates of the intrinsic physical property values ​​based on the Hansen solubility are obtained for the target water. w (δD w , δP w , δH w) can also be obtained experimentally. Alternatively, the coordinates of the intrinsic physical properties of the target water can be obtained from literature values ​​or databases. The coordinates of the intrinsic physical properties of the target water can also be obtained using the Hansen Solubility Parameter in Practice (HSPiP) software.

[0034] In step (c), the coordinates C of the characteristic physical property values ​​of the target scale s and the coordinates of the specific physical properties of the target water, C w A suitable scale dispersant is selected based on its positional relationship in coordinate space with the scale dispersant. There are several possible embodiments of the specific method and criteria for selection in step (c). Each embodiment of the selection step (c) will be described below.

[0035] [First mode: Selection in three-dimensional coordinates] According to the first aspect, the selection step (c) is a selection method in a three-dimensional coordinate space. The scale dispersant selection step (c) according to the first aspect is a selection method in a three-dimensional coordinate space. s (δD s , δP s , δH s ), the coordinates of the target water C w (δD w , δP w , δH w ), coordinate C of the scale dispersant to be selected a (δD a , δP a , δH a ), the coordinates C of the characteristic physical property values ​​of the target scale s and the coordinates C of the specific physical properties of the target water w Distance R a When The following formula (1): 4(δD a -δD w ) 2 +(δP a -δP w ) 2 +(δH a -δH w ) 2 ≦(R a ) 2 (1) The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant.

[0036] Referring to FIG. 1, in a three-dimensional coordinate space consisting of dispersion force δD, dipole-dipole force δP, and hydrogen bond force δH, the coordinates C of the target water molecule are w The center is R and the radius is a A sphere of R is shown, where R a is the coordinate of the target water C w and the coordinate C of the target scale s is the distance between R a is expressed by the following formula (2): R a = [4(δD s -δD w ) 2 +(δP s -δP w ) 2 +(δH s -δH w ) 2 ] 1 / 2 (2) is defined as:

[0037] In this embodiment, the coordinates C of the target water w The center is R and the radius is a On the surface of the sphere and inside the sphere, coordinate C a The substance having the coordinate C of the target water can be selected as a scale dispersant. w , and the coordinates of the target scale C s Substances having such a coordinate positional relationship with respect to the target scale and the target scale dispersant have good affinity with the target water, and therefore can be preferably used as dispersants. w Coordinate C is close to a is more preferred as a dispersant.

[0038] In the present invention, the coordinate C aThe substance having the coordinate C may be a compound that functions as a dispersant by itself. The compound may be a low molecular weight compound such as an acid or a chelating agent, or may be a polymer compound composed of one or more types of repeating units, and is not particularly limited. a The substance having the coordinate C may be a monomer constituting a repeating unit of a polymer compound or a single modifying group of a compound that functions as a dispersant. a (δD a , δP a , δH a Once the range of coordinates is determined, substances that satisfy these coordinates can be selected based on the information in the database. According to the present invention, not only compounds that function as dispersants by themselves, but also compound parts such as monomers and modifying groups can be considered as dispersants and can be used as selection targets. This advantageously makes it possible to select effective dispersants from a wider range of options.

[0039] Coordinate C a Examples of the main chain of a polymer compound that can be selected as a substance having the coordinate C include an allylamine polymer and a diallylamine polymer. a Examples of modifying groups of polymer compounds include maleic acid, ascorbic acid, nicotinic acid, acrylic acid, dimethyldiallylammonium chloride, difurfuryl disulfide, and sulfur dioxide, which can be polymerized with the monomers that make up the main chain. The chelating agent may be one that forms a complex or coordinates with substances such as calcium, iron, and aluminum that are commonly contained in the target scale. Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and hydroxyethylethylenediamine. Triacetic acid However, in the present invention, the compounds, monomers, or modifying groups that can be selected are not limited to these, and any compound having a coordinate C that satisfies a predetermined condition can be used. a (δD a , δP a , δH a ) is sufficient.

[0040] The selection process according to the first aspect selects dispersants in HSP based on the unprecedented concept of selecting substances whose coordinates are within a sphere of radius Ra, with water at the center, and the target scale. This has a significant advantage over conventional techniques in that it makes it possible to select dispersants that are highly effective.

[0041] [Second mode: Selection using the coordinates of the target water as the reference axis in two-dimensional coordinate space] According to the second aspect, the selection step (c) is a selection method in a two-dimensional coordinate space consisting of a dispersion force δD and a dipole-dipole force δP. The scale dispersant selection step according to the second aspect is performed by selecting a scale dispersant based on the coordinates C of the target scale. s (δD s , δP s ), the coordinates of the target water C w (δD w , δP w ), coordinate C of the scale dispersant to be selected a (δD a , δP a ), (i) δP s ≧δP w In the case of δP a ≦δP w The coordinate C satisfies a A substance having the following structure is selected as a scale dispersant, (ii) δP s ≦δP w In the case of δP a ≧δP w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant.

[0042] Referring to FIG. 2, in a three-dimensional coordinate space consisting of dispersion force δD, dipole-dipole force δP, and hydrogen bond force δH, the coordinates C of the target water molecule are w and the coordinate C of the target scale s is plotted. In Figure 2, the δH axis direction is represented by a dashed arrow. In this embodiment, a selection process is carried out that is independent of the δH axis. The reason why the hydrogen bonding strength δH does not need to be taken into consideration when selecting a dispersant is that experiments have shown that the δH term has little effect when considering affinity with the target water.

[0043] A selection method that does not depend on the δH axis can be considered in a two-dimensional coordinate space consisting of dispersion force δD and dipole-dipole force δP. Such a two-dimensional coordinate space is shown in Figure 3. In Figures 2 and 3, the coordinates C of the target water w (δD w , δP w ), and the δDw axis parallel to the δD axis and the δPw axis parallel to the δP axis are set. The δDw axis and the δPw axis are respectively indicated by dashed lines.

[0044] In this embodiment, the specific selection method is to select the coordinate C s In the coordinate region where the coordinate C exists, a A substance having the following formula is selected as a dispersant. This is because, when considering affinity with the target water, the D term, which is the London dispersion force of the target scale coordinate Cs, can be made closer to the target water coordinate Cw. In this embodiment and the third embodiment described later, the coordinate C a The definition of the substance having the coordinate C within a predetermined range may be the same as in the first embodiment. a (δD a , δP a ) can be selected as the dispersant.

[0045] In FIG. 3, the two-dimensional coordinate space is divided into a first quadrant Q1, a second quadrant Q2, a third quadrant Q3, and a fourth quadrant Q4 by the δDw axis and the δPw axis. For example, the coordinate C of the object scale s If it is in the fourth quadrant Q4 as shown in the figure, the coordinate C of the target scale s The coordinate regions symmetrical with respect to the δDw axis are the first quadrant Q1 and the second quadrant Q2. s If it is in the fourth quadrant Q4, then the coordinate C is in the first quadrant Q1 or the second quadrant Q2. a (δD a , δP a ) is selected as a dispersant. s Similarly, when it is in the third quadrant Q3, the coordinate C of the target scales The coordinate regions symmetrical with respect to the δDw axis are the first quadrant Q1 and the second quadrant Q2, and the coordinate C a (δD a , δP a ) is selected as a dispersant. In other words, the coordinates C of the target water w , coordinates of the target scale C s But δP s ≦δP w If δP a ≧δP w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant: δD a The value of is not particularly limited.

[0046] On the other hand, the coordinate C of the target scale s If it is in the first quadrant Q1 or the second quadrant Q2, the coordinate C of the target scale s The coordinate regions symmetrical with respect to the δDw axis are the third quadrant Q3 and the fourth quadrant Q4. Therefore, if the coordinate C a (δD a , δP a ) is selected as a dispersant. In other words, the coordinates C of the target water w , coordinates of the target scale C s But δP s ≧δP w If δP a ≦δP w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant: δD a The value of is not particularly limited.

[0047] In either case, the value of the hydrogen bonding strength δH term of the dispersant is not limited, and δH a can be any value.

[0048] Next, as a modification of the second embodiment, the coordinates C of the target water w For the coordinate C of the target scale s The coordinate region where coordinate C exists is located in the diagonal region.a (δD a , δP a Here, a certain region and a region diagonally opposite each other refer to two regions that include a vertical angle formed by the intersection of the δDw axis and the δPw axis.

[0049] According to a variant of the second aspect, the coordinates C of the object scale s is in the fourth quadrant Q4 as shown in the figure, the coordinate C is in the second quadrant Q2, which is the diagonal of the a (δD a , δP a ) is selected as a dispersant. s ≦δP w and δD s ≧δD w In the case of δP a ≧δP w and δD a ≦δD w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant.

[0050] Similarly, the coordinate C of the target scale s If is in the first quadrant Q1, then the coordinate C is in the third quadrant Q3, which is the diagonal of a (δD a , δP a ) is selected as a dispersant. s ≧δP w and δD s ≧δD w In the case of δP a ≦δP w and δD a ≦δD w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant.

[0051] Coordinate C of the target scale s If is in the second quadrant Q2, then the coordinate C is in the fourth quadrant Q4, which is the diagonal of a (δD a , δP a) is selected as a dispersant. s ≧δP w and δD s ≦δD w In the case of δP a ≦δP w and δD a ≧δD w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant.

[0052] Coordinate C of the target scale s If is in the third quadrant Q3, then the coordinate C is in the first quadrant Q1, which is the diagonal of a (δD a , δP a ) is selected as a dispersant. s ≦δP w and δD s ≦δD w In the case of δP a ≧δP w and δD a ≧δD w The coordinate C satisfies a A substance having the following properties is selected as a scale dispersant.

[0053] In this embodiment, the δH of the scale dispersant a The value of is not particularly limited.

[0054] The selection process according to the second embodiment and its variants is advantageous over the first embodiment in that it can further limit the effective dispersants.

[0055] [Third mode: Selection based on affinity with target water in two-dimensional coordinates] According to a third aspect, the selection step (c) is a selection method in a two-dimensional coordinate space consisting of a dispersion force δD and a dipole-dipole force δP. The scale dispersant selection step according to the third aspect is performed by selecting a scale dispersant based on the coordinates C s (δD s , δP s ), the coordinates of the target water C w (δD w , δP w), coordinate C of the scale dispersant to be selected a (δD a , δP a ), coordinate C w and coordinate C s The distance between a When (1)R a If is less than or equal to 9.5, δD a But (δD w -0.5)~(δD w +4.5) and δP a But (δP w -10)~(δP w +8) a A substance having the following structure is selected as a scale dispersant, (2)R a If is greater than 9.5, δD a (δD w +0.5)~(δD w +4.5) and δP a But (δP w -10)~(δP w +8) a A substance having the following properties is selected as a scale dispersant.

[0056] (1) Scale with good water affinity (R a ≦9.5) Referring to FIG. 4, in a two-dimensional coordinate space consisting of dispersion force δD and dipole-dipole force δP, the coordinates C of the target water w Centered at and radius R a The circle with the coordinate C of the target scale is shown. s If the scale is on or inside the circle, it is defined as a scale that has good affinity with the target water. In this case, δD a But (δD w -0.5)~(δD w +4.5) and δP a But (δP w -10)~(δP w +8) a A substance having the following structure can be selected as a scale dispersant.

[0057] In this embodiment, the hydrogen bonding strength of the dispersant does not need to be taken into consideration. a can be any value.

[0058] In Figure 4, the target water coordinate C when pure water is the target water w (δD w = 15.5, δP w = 16) based on the coordinate C of a scale dispersant with good affinity for water. a The preferred region where the above is located is indicated by a two-dot chain line. Figure 4 plots the coordinate values ​​of the target silica-based scale and geothermal silica-based scale actually obtained. It also plots the coordinate values ​​of various dispersants and substances used as dispersant modifying groups. In Figure 4, the target silica-based scale is the coordinate of the silica-based scale used in selection as the target scale in the selection method of this embodiment, and the geothermal silica-based scale is the coordinate of silica-based scale derived from a geothermal power plant in Japan. Also, in Figure 4, "good solubility," "semi-soluble," and "insoluble" indicate the dispersibility of the dispersant. Specifically, the dispersant was added to pure water at a concentration of 0.2 mass% and mixed in a bottle, and the evaluation results were based on the degree of turbidity. "Good solubility" indicates a highly dispersible dispersant, with more than half of the liquid in the bottle being turbid. "Semi-soluble" indicates a state in which half of the liquid in the bottle was turbid. "Insoluble" indicates a dispersant with low dispersibility, with precipitates forming in the liquid in the bottle or less than half being turbid.

[0059] (2) Scale with poor water affinity (R a >9.5) Next, referring to FIG. 5, similarly to FIG. 4, the coordinates C w Centered at and radius R a = 9.5 circle is shown, and the coordinate C of the target scale is s is outside the circle. This scale is defined as a scale with poor affinity with the target water. In this case, δD a (δD w +0.5)~(δD w +4.5) and δP aBut (δP w -10)~(δP w +8) a A substance having the following structure can be selected as a scale dispersant.

[0060] In Figure 5, the target water coordinate C when pure water is used as the target water. w (δD w = 15.5, δP w = 16) is selected based on the coordinate C of a dispersant suitable for scales with poor affinity for water. a The preferred region where the above is located is indicated by a two-dot chain line. Figure 5 plots the coordinate values ​​of the target silica-based scale and geothermal silica-based scale that were actually obtained. It also plots the coordinate values ​​of various dispersants and substances used as dispersant modifying groups.

[0061] The selection step according to the third embodiment is advantageous in that it allows for more effective drug selection compared to the first and second embodiments.

[0062] According to the first embodiment of the present invention, it is possible to select a scale dispersant that is suitable for the target water and target scale. Therefore, it becomes possible to select a scale dispersant for each plant system where scale adhesion is a concern, and it becomes possible to efficiently suppress scale adhesion.

[0063] [Second embodiment: Method for producing scale dispersant] According to a second embodiment, the present invention relates to a method for producing a scale dispersant. The method for producing a scale dispersant includes the following steps. A step of selecting a scale dispersant or a modifying group having predetermined coordinates based on the method for selecting a scale dispersant described in the first embodiment. A step of preparing a scale dispersant based on the selected scale dispersant or modifying group.

[0064] The first step of this embodiment can be carried out by the method described in the first embodiment, so a description thereof will be omitted here. In the second step, the scale dispersant can be prepared by synthesizing a polymer compound or modifying the main chain with a modifying group using the dispersant, compound, monomer, or modifying group selected in the first step, as necessary. Two or more dispersants selected in the first step can also be combined to form a scale dispersant. For example, a scale dispersant can be formed by combining a chelating agent selected in the first step with a polymer compound having a modifying group also selected in the first step.

[0065] According to this embodiment, a scale dispersant can be produced that is suited to the components of the target water and the target scale, and the scale dispersant can be used to inhibit the adhesion of scale.

[0066] [Third embodiment: method for inhibiting scale adhesion] According to a third embodiment, the present invention relates to a method for inhibiting adhesion of scale. The method for inhibiting adhesion of scale includes the following steps. (I) A step of selecting a scale dispersant by the method for selecting a scale dispersant described in the first embodiment (II) adding the selected scale dispersant to the geothermal water of the geothermal power generation system. In the selection process, the coordinates C of the intrinsic physical property values ​​of the geothermal water w The method includes the step of obtaining:

[0067] Step (I) of this embodiment can be carried out by the method described in the first embodiment. In this embodiment, the target scale is scale generated in a geothermal power generation system, and the target water is geothermal water at the location where the scale dispersant is added. Therefore, in the method for inhibiting scale adhesion of this embodiment, a scale dispersant can be selected so as to be compatible with the target water of the target geothermal power generation system.

[0068] For example, in a geothermal power generation system that obtains geothermal water from two or more production wells, the composition of the geothermal water obtained from each production well may differ, and the coordinates C of the characteristic physical properties based on HSP w In this case, in step (I) of this embodiment, the coordinates C of the intrinsic physical properties of the geothermal water derived from two or more different production wells may be different. w and preferably includes a step of selecting a scale dispersant suitable for the geothermal water derived from each production well. For example, it is preferable to separately select a first scale dispersant suitable for the first target water obtained from a first production well and a second scale dispersant suitable for the second target water obtained from a second production well.

[0069] In step (II), the scale dispersant selected in step (I) is prepared and added to the target water. The addition may be intermittent or continuous. The amount of scale dispersant to be added can also be determined appropriately by those skilled in the art.

[0070] Next, a geothermal power generation system and the addition of a scale dispersant will be described with reference to Figure 6. Figure 6 is a conceptual flow diagram showing an example of a binary cycle geothermal power generation system. The geothermal power generation system can be composed of a production well 1, a first steam separator 2, a first turbine / generator 3, a hot water tank 4, a second steam separator 5, an evaporator 6, a separator 7, a second turbine / generator 8, a feedwater heater 9, an air-cooled condenser 10, a preheater 11, a flash tank 12, a hot water pit 13, a reinjection pump 14, and a reinjection well 15. Optionally, a facility 16 for downstream heat utilization may also be included. In Figure 6, the flow of geothermal water is indicated by solid arrows, and the flow of a low-boiling-point medium is indicated by dashed arrows. The area surrounded by a dashed line indicates the flash power generation area.

[0071] A brief description of the flow of materials in a geothermal power generation system follows. The production well 1 is a well that delivers hot water, steam, or a mixture of these (geothermal water) from the underground geothermal reservoir to the surface. The geothermal water delivered from the production well 1 is separated into gaseous steam and liquid hot water in the first steam separator 2. The separated steam is directed to the first turbine / generator 3, where it is used to rotate the turbine and generate electricity. The steam that passes through the first turbine / generator 3 is cooled in a condenser (not shown) and directed to the reinjection well 15 through piping (not shown). Meanwhile, the hot water separated in the first steam separator 2 is directed to the second steam separator 5 via the hot water tank 4. The gaseous components separated in the second steam separator 5 are directed to the evaporator 6, where they are used to heat a low-boiling-point solvent. The hot water, re-liquefied by heating the low-boiling-point solvent, is then directed to the flash tank 12. The liquid component separated in the second steam separator 5 is guided to a preheater 11 to heat the low-boiling-point medium, and then to a flash tank 12. In the flash tank 12, the hot water is depressurized, and the generated steam is released into the atmosphere. The liquid component remaining after depressurization is guided to a hot water pit 13, and a portion is returned to a reinjection well 15 by a reinjection pump 14, while the remaining portion is guided to a facility 16 for downstream heat utilization, such as a hot spring facility.

[0072] 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 evaporator 6, and the two-phase low boiling point medium is separated into gas and liquid phases in separator 7, with the gas phase low boiling point medium being led to second turbine / generator 8. The low boiling point medium used to rotate the turbine is condensed and liquefied in feed heater 9, has its heat dissipated in air-cooled condenser 10, and is led to preheater 11. In preheater 11, the liquefied low boiling point medium is heated again by geothermal water and circulated to evaporator 6.

[0073] In this embodiment, the scale dispersant is preferably added at one or more of the following locations: arrow a immediately after the production well is released; arrow b leading to the second steam separator 5 via the first steam separator 2; arrow c leading to the preheater 11 via the second steam separator 5; arrow d leading from the hot water pit 13 to the return pump 14; or arrow e leading to the facility 16 for downstream heat utilization via the return pump 14. Adding the scale dispersant at the location indicated by arrow a has the effect of dispersing silica adhering to steam pipes, heat exchangers, steam separators, valves, etc. The type of scale dispersant added at each location may be the same or different. When the geothermal water flowing through the addition locations has different compositions, selecting and adding a scale dispersant compatible with each composition is the optimal method for inhibiting scale buildup.

[0074] The geothermal power generation system in which the method for inhibiting scale deposition according to this embodiment is implemented is not limited to the binary cycle geothermal power generation system shown in the figure, but can be applied to any geothermal power generation system.

[0075] According to the method for inhibiting scale deposition of this embodiment, it is possible to effectively and economically inhibit scale deposition by using a dispersant selected according to the target water and target scale of the geothermal power generation system. [Industrial Applicability]

[0076] The method for selecting a scale dispersant, the method for producing a scale dispersant, and the scale inhibition method according to the present invention can be applied to inhibiting scale buildup in various plant systems. [Explanation of symbols]

[0077] C s Coordinates of the target scale, C w Target water coordinates Q1 1st quadrant, Q2 2nd quadrant, Q3 3rd quadrant, Q4 4th quadrant

Claims

1. A process of obtaining coordinates Cs of intrinsic physical properties based on the Hansen solubility for a target scale; A step of obtaining coordinates Cw of the intrinsic physical property value based on the Hansen solubility for the target water; selecting a scale dispersant based on the positional relationship between the coordinate C s of the characteristic physical property value of the target scale and the coordinate C w of the characteristic physical property value of the target water; A method for selecting a scale dispersant, comprising: The intrinsic physical property value is expressed by three-dimensional coordinates consisting of dispersion force δD, dipole-dipole force δP, and hydrogen bonding force δH, Coordinate C of the target scale ｓ (δD ｓ , δP ｓ , δH ｓ ), The coordinates C of the target water ｗ (δD ｗ , δP ｗ , δH ｗ ), Coordinate C of the scale dispersant to be selected ａ (δD ａ , δP ａ , δH ａ ), Coordinates C of the inherent physical property values ​​of the target scale ｓ and the coordinates C of the inherent physical property values ​​of the target water ｗ Distance R ａ When The step of selecting the scale dispersant includes: The following formula (1): 4(δD ａ -δD ｗ ) ２ +(δP ａ -δP ｗ ) ２ +(δH ａ -δH ｗ ) ２ ≦(R ａ ) ２ (1) Coordinate C satisfies ａ A selection method for selecting a substance having the above formula as a scale dispersant.

2. A process of obtaining coordinates Cs of intrinsic physical properties based on the Hansen solubility for the target scale; A step of obtaining coordinates Cw of the intrinsic physical property value based on the Hansen solubility for the target water; selecting a scale dispersant based on the positional relationship between the coordinate C s of the characteristic physical property value of the target scale and the coordinate C w of the characteristic physical property value of the target water; A method for selecting a scale dispersant, comprising: The intrinsic physical property value is expressed by two-dimensional coordinates consisting of dispersion force δD and dipole-dipole force δP, Coordinate C of the target scale ｓ (δD ｓ , δP ｓ ), The coordinates C of the target water ｗ (δD ｗ , δP ｗ ), Coordinate C of the scale dispersant to be selected ａ (δD ａ , δP ａ ) and The step of selecting the scale dispersant includes: (i) δP ｓ ≧δP ｗ In the case of δP ａ ≦δP ｗ Coordinate C satisfies ａ A substance having the following structure is selected as a scale dispersant, (ii) δP ｓ ≦δP ｗ In the case of δP ａ ≧δP ｗ Coordinate C satisfies ａ A selection method for selecting a substance having the above formula as a scale dispersant.

3. (ia) δP ｓ ≧δP ｗ and δD ｓ ≧δD ｗ in the case of, δP ａ ≦δP ｗ and δD ａ ≦δD ｗ Coordinate C satisfies ａ A substance having the following structure is selected as a scale dispersant, (ib) δP ｓ ≧δP ｗ and δD ｓ ≦δD ｗ in the case of, δP ａ ≦δP ｗ and δD ａ ≧δD ｗ Coordinate C satisfies ａ A substance having the following structure is selected as a scale dispersant, (iia) δP ｓ ≦δP ｗ and δD ｓ ≦δD ｗ in the case of, δP ａ ≧δP ｗ and δD ａ ≧δD ｗ Coordinate C satisfies ａ A substance having the following structure is selected as a scale dispersant, (iib) δP ｓ ≦δP ｗ and δD ｓ ≧δD ｗ in the case of, δP ａ ≧δP ｗ and δD ａ ≦δD ｗ Coordinate C satisfies ａ The selection method according to claim 2, wherein a substance having the following formula is selected as a scale dispersant.

4. A step of obtaining coordinates Cs of intrinsic physical properties based on the Hansen solubility for the target scale; A step of obtaining coordinates Cw of the intrinsic physical property value based on the Hansen solubility for the target water; selecting a scale dispersant based on the positional relationship between the coordinate C s of the characteristic physical property value of the target scale and the coordinate C w of the characteristic physical property value of the target water; A method for selecting a scale dispersant, comprising: The intrinsic physical property value is expressed by two-dimensional coordinates consisting of dispersion force δD and dipole-dipole force δP, Coordinate C of the target scale ｓ (δD ｓ , δP ｓ ), The coordinates C of the target water ｗ (δD ｗ , δP ｗ ), Coordinate C of the scale dispersant or its modifying group to be selected ａ (δD ａ , δP ａ ), Coordinate C ｗ and coordinate C ｓ The distance between ａ When The step of selecting the scale dispersant includes: (1) R ａ If is less than or equal to 9.5, δD ａ (δD ｗ -0.5) to (δD ｗ +4.5), and δP ａ (δP ｗ -10) to (δP ｗ +8) ａ A substance having the following structure is selected as a scale dispersant, (2) R ａ If is greater than 9.5, δD ａ (δD ｗ +0.5) to (δD ｗ +4.5), and δP ａ (δP ｗ -10) to (δP ｗ +8) ａ A selection method for selecting a substance having the above formula as a scale dispersant.

5. The selection method according to any one of claims 1 to 4, wherein the target water is selected from tap water, sewage, well water, seawater, fresh water, river water, pure water, geothermal water, industrial water, and factory wastewater.

6. The selection method according to any one of claims 1 to 4, wherein the scale dispersant is selected from allylamine, diallylamine, maleic acid, ascorbic acid, nicotinic acid, acrylic acid, dimethyldiallylammonium chloride, difurfuryl disulfide, sulfur dioxide, or a polymer containing one or more of these as a monomer.

7. The selection method according to claim 6 , wherein the scale dispersant includes a chelating agent.

8. A method for inhibiting scale deposition in a geothermal power generation system, comprising: (I) a step of selecting a scale dispersant by the method for selecting a scale dispersant according to any one of claims 1 to 4; (II) adding the selected scale dispersant to the geothermal water of the geothermal power generation system; Including, In the selection step, the coordinate C of the inherent physical property value of the geothermal water ｗ The method includes the step of obtaining

9. Coordinate C of the characteristic physical properties of geothermal water derived from two or more different production wells ｗ The method of claim 8, further comprising the step of obtaining a scale dispersant corresponding to the geothermal water derived from each production well.

Images