Performance evaluation method for coal gasification grey water scale inhibition dispersant

Abstract

The invention relates to the technical field of chemical industry, and discloses a coal gasification grey water scale inhibition dispersant performance evaluation method, which comprises: determining the normal temperature and pressure scale inhibition rate, the high temperature and high pressure scale inhibition rate, the dispersion performance and the phosphorus content of a to-be-evaluated scale inhibition dispersant, and calculating the score of the to-be-evaluated scale inhibition dispersant. According to the scheme, when the performance of the coal gasification grey water scale inhibition dispersant is evaluated, multiple aspects including the scale inhibition rate, the dispersion performance and the phosphorus content are considered, so that the evaluation is more comprehensive, and the performance of the coal gasification grey water scale inhibition dispersant can be more accurately evaluated.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and specifically to a method for evaluating the performance of scale inhibitors and dispersants in coal gasification ash water. Background Technology

[0002] Clean and efficient utilization of coal is an inevitable trend in energy development, and coal gasification technology is a key technology for clean and efficient utilization of coal, holding an important position in the field of clean coal technology.

[0003] During coal gasification, high-temperature, high-pressure crude syngas is washed and cooled to produce black water. After flash evaporation and flocculation sedimentation, the solid content of this black water is significantly reduced, forming coal gasification ash water, or simply ash water. Most of this ash water is returned to the coal gasification system for recycling. In this recycling process, scale inhibitors and dispersants play a crucial role and are the core element for achieving ash water reuse. Ash water typically has characteristics such as high pressure, high temperature, high turbidity, and high hardness, leading to frequent deposition and scaling of suspended solids during recycling in the coal gasification system, severely affecting the normal operation of the equipment. Scale inhibitors and dispersants can maintain the stable dispersion of solid particles in the ash water, preventing their deposition and scaling that could clog the equipment.

[0004] Therefore, accurate evaluation of the performance of scale inhibitors and dispersants in coal gasification ash water is crucial for obtaining ideal scale inhibitors and dispersants. However, the evaluation results provided by existing technologies are not accurate enough, resulting in unsatisfactory practical application effects of the obtained scale inhibitors and dispersants in coal gasification ash water. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that the existing technology has poor evaluation accuracy when evaluating the performance of scale inhibitors and dispersants in coal gasification ash water, resulting in unsatisfactory actual application effects of the obtained scale inhibitors and dispersants in coal gasification ash water, and to provide a method for evaluating the performance of scale inhibitors and dispersants in coal gasification ash water.

[0006] The performance evaluation method for the scale inhibitor and dispersant in coal gasification ash water includes: preparing a first blank sample based on coal gasification ash water, borax buffer solution, and sodium bicarbonate solution; preparing a first test sample based on coal gasification ash water, the scale inhibitor and dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution; and preparing a second test sample based on coal gasification ash water, the scale inhibitor and dispersant to be evaluated after pre-temperature and pressure treatment, borax buffer solution, and sodium bicarbonate solution. The first blank sample, the first test sample, and the second test sample are heated and then filtered. The filtrates from the first blank sample, the first test sample, and the first test sample are titrated. The titration volume is determined based on the amount of titrant consumed corresponding to the filtrate of the first blank sample and the amount of titrant consumed corresponding to the filtrate of the first test sample. The first scale inhibition rate of the scale inhibitor / dispersant to be evaluated was calculated based on the consumption of titrant corresponding to the filtrate of the first blank sample and the consumption of titrant corresponding to the filtrate of the second test sample. A second blank sample and a reference sample were prepared based on water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. A test sample was prepared based on water, calcium salt solution, the scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. The turbidity of the second blank sample was measured after heating and dispersion treatment. The turbidity of the reference sample and the test sample was measured after heating and dispersion treatment and settling treatment. The dispersion performance of the scale inhibitor / dispersant to be evaluated was calculated based on the turbidity of the second blank sample, the reference sample, and the test sample. The test sample was prepared based on the scale inhibitor and dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution, ammonium molybdate solution and ascorbic acid solution, and the absorbance was measured. The phosphorus content of the scale inhibitor and dispersant to be evaluated was calculated based on the absorbance. The score of the scale inhibitor / dispersant to be evaluated is calculated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

[0007] In this embodiment of the application, the scale inhibitor / dispersant to be evaluated after being subjected to a preset temperature and pressure treatment is obtained through the following process: The scale inhibitor and dispersant to be evaluated was placed in a reactor and kept at a pressure of 4.4MPa-4.6MPa and a temperature of 210℃-230℃ for 1-3 hours, and then the temperature and pressure were reduced.

[0008] In this embodiment of the application, the preparation of the first blank sample based on coal gasification ash water, borax buffer solution and sodium bicarbonate solution includes: adding coal gasification ash water, borax buffer solution and sodium bicarbonate solution to a volumetric flask in sequence, and then adding water to make up to the volume mark of the volumetric flask; The preparation of the first test sample based on coal gasification ash water, the scale inhibitor and dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution includes: Add coal gasification ash water, scale inhibitor and dispersant to be evaluated, borax buffer solution and sodium bicarbonate solution to the volumetric flask in sequence, and then add water to make up to the volume mark of the volumetric flask. The preparation of the second test sample based on coal gasification ash water, a scale inhibitor / dispersant to be evaluated after pre-treated at a preset temperature and pressure, borax buffer solution, and sodium bicarbonate solution includes: Add coal gasification ash water, the scale inhibitor and dispersant to be evaluated after pre-temperature and pressure treatment, borax buffer solution, and sodium bicarbonate solution to the volumetric flask in sequence, and then add water to make up to the volume mark of the volumetric flask.

[0009] In the embodiments of this application, during the preparation of the first blank sample, the first test sample and the second test sample, when adding sodium bicarbonate solution, the molar ratio of added bicarbonate ions to calcium ions in coal gasification ash water is controlled to be 1:(2.8~3.2).

[0010] In this embodiment of the application, the titration of the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample includes: First, dilute the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample. Then, add potassium hydroxide solution and calcium carboxylic acid indicator, and titrate with disodium ethylenediaminetetraacetate solution.

[0011] In this embodiment of the application, the step of calculating the first scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the first test sample, and calculating the second scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the second test sample, includes: The calcium ion concentration in the filtrate of the first blank sample is determined based on the amount of titrant consumed corresponding to the filtrate of the first test sample, the calcium ion concentration in the filtrate of the first test sample is determined based on the amount of titrant consumed corresponding to the filtrate of the first test sample, and the calcium ion concentration in the filtrate of the second test sample is determined based on the amount of titrant consumed corresponding to the filtrate of the second test sample. The first scale inhibition rate of the scale inhibitor to be evaluated is calculated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the first test sample, and the second scale inhibition rate of the scale inhibitor to be evaluated is calculated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the second test sample.

[0012] In this embodiment of the application, the preparation of the second blank sample and reference sample based on water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin includes: Add water, calcium salt solution, sodium tetraborate solution and sodium bicarbonate solution to the volumetric flask in sequence, and dilute with water to the volume mark of the volumetric flask. Transfer the solution in the volumetric flask to a mixing container, and then add kaolin. The test sample, prepared based on water, calcium salt solution, scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin, includes: Add water, calcium salt solution, scale inhibitor and dispersant to be evaluated, sodium tetraborate solution and sodium bicarbonate solution to the volumetric flask in sequence, and add water to make up to the volume mark of the volumetric flask. Transfer the solution in the volumetric flask to a mixing container, and then add kaolin.

[0013] In this embodiment of the application, the heating and dispersion treatment of the second blank sample includes: The second blank sample was ultrasonically vibrated at 39℃-41℃ for 18-22 minutes. The process of heating and dispersing the reference sample and the test sample, followed by a settling process, includes: The reference sample and the test sample were ultrasonically vibrated at 39℃-41℃ for 18min-22min, and then left to stand at 39℃-41℃ for 4h-6h.

[0014] In the embodiments of this application, the dispersion performance of the scale inhibitor dispersant to be evaluated is calculated based on the following formula; ; in, The dispersion performance of the scale inhibitor / dispersant to be evaluated; The turbidity of the test sample; The turbidity of the reference sample; The turbidity of the second blank sample.

[0015] In this embodiment of the application, the calculation of the score of the scale inhibitor / dispersant to be evaluated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content includes: The first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content were normalized. The score of the scale inhibitor / dispersant to be evaluated is calculated based on the normalized results of the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content, as well as the preset weights of the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

[0016] The above technical solution includes: preparing a first blank sample based on coal gasification ash water, borax buffer solution, and sodium bicarbonate solution; preparing a first test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution; and preparing a second test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated treated at a preset temperature and pressure, borax buffer solution, and sodium bicarbonate solution. The first blank sample, the first test sample, and the second test sample are heated and then filtered. The filtrate from the first blank sample, the first test sample, and the first test sample is titrated. The first scale inhibition rate of the scale inhibitor / dispersant to be evaluated is calculated based on the titration volume corresponding to the filtrate of the first blank sample and the titration volume corresponding to the filtrate of the first test sample. The first scale inhibition rate is calculated based on the titration volume corresponding to the filtrate of the first blank sample and the titration volume corresponding to the filtrate of the second test sample. The second scale inhibition rate of the scale inhibitor / dispersant to be evaluated was calculated based on the amount of liquid consumed. A second blank sample and a reference sample were prepared using water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. A test sample was prepared using water, calcium salt solution, the scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. The turbidity of the second blank sample was measured after heating and dispersion treatment. The turbidity of the reference sample and the test sample was measured after heating, dispersion treatment, and settling treatment. The dispersion performance of the scale inhibitor / dispersant to be evaluated was calculated based on the turbidity of the second blank sample, reference sample, and test sample. A test sample was prepared using the scale inhibitor / dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution, ammonium molybdate solution, and ascorbic acid solution, and the absorbance was measured. The phosphorus content of the scale inhibitor / dispersant to be evaluated was calculated based on the absorbance. The score of the scale inhibitor / dispersant to be evaluated was calculated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content. The solution provided in this application takes into account multiple aspects when evaluating the performance of scale inhibitors and dispersants in coal gasification ash water, including scale inhibition rate, dispersion performance, and phosphorus content, making the evaluation more comprehensive and enabling a more accurate evaluation of the performance of scale inhibitors and dispersants in coal gasification ash water.

[0017] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings: Figure 1 The illustration shows a schematic flowchart of a method for evaluating the performance of a scale inhibitor and dispersant in coal gasification ash water according to an embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0022] As described in the background section, the clean and efficient utilization of coal is an inevitable trend in energy development, and coal gasification technology is a key technology for the clean and efficient utilization of coal, holding an important position in the field of clean coal technology. During coal gasification, high-temperature, high-pressure crude syngas is washed and cooled to produce black water (high solid content and black in color, hence the name black water). After flash evaporation and flocculation sedimentation, the solid content of this black water is significantly reduced, forming coal gasification ash water, or simply ash water. Most of the ash water is returned to the coal gasification system for recycling. In this recycling process, scale inhibitors and dispersants play a crucial role and are the core element for achieving ash water reuse. Ash water typically has characteristics such as high pressure, high temperature, high turbidity, and high hardness, leading to frequent deposition and scaling of suspended solids in the ash water during recycling in the coal gasification system, seriously affecting the normal operation of the equipment. Scale inhibitors and dispersants can keep solid particles in a stable dispersed state in the ash water, preventing them from depositing and scaling, thus preventing equipment blockage. Therefore, accurate evaluation of the performance of scale inhibitors and dispersants in coal gasification ash water is crucial for obtaining ideal scale inhibitors and dispersants that can effectively slow down ash water scaling, extend production cycles, and reduce wastewater discharge. However, the evaluation methods provided in the existing technology have poor accuracy, resulting in less than ideal practical application effects of the obtained scale inhibitors and dispersants in coal gasification ash water.

[0023] To address this, one embodiment of this application provides a method for evaluating the performance of scale inhibitors and dispersants in coal gasification ash water, such as... Figure 1 As shown, the performance evaluation method for the scale inhibitor and dispersant in coal gasification ash water may include the following steps: Step 101: Prepare a first blank sample based on coal gasification ash water, borax buffer solution, and sodium bicarbonate solution; prepare a first test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution; and prepare a second test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated after pre-treated at a preset temperature and pressure, borax buffer solution, and sodium bicarbonate solution. After heating the first blank sample, the first test sample, and the second test sample, filter them separately. Titrate the filtrate from the first blank sample, the first test sample, and the first test sample. Calculate the first scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the first test sample. Calculate the second scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the second test sample.

[0024] That is, the first test sample contains the scale inhibitor and dispersant to be evaluated that has not been treated with the preset temperature and pressure, the second test sample contains the scale inhibitor and dispersant to be evaluated that has been treated with the preset temperature and pressure, and the first blank sample does not contain the scale inhibitor and dispersant to be evaluated. The other components in the three samples have the same composition and content.

[0025] In this embodiment, the scale inhibitor / dispersant to be evaluated after pre-treatment with preset temperature and pressure can specifically be a scale inhibitor / dispersant to be evaluated after high-temperature and high-pressure treatment. That is, the first test sample contains a scale inhibitor / dispersant to be evaluated at room temperature and pressure, while the second test sample contains a scale inhibitor / dispersant to be evaluated after high-temperature and high-pressure treatment. Therefore, the first scale inhibition rate can also be called the room temperature and pressure scale inhibition rate, and the second scale inhibition rate can also be called the high-temperature and high-pressure scale inhibition rate.

[0026] In practical applications, the scale inhibitor and dispersant to be evaluated can be placed in a reactor to simulate the working conditions of a coal gasification system. The reactor is maintained at a pressure of 4.4 MPa-4.6 MPa and a temperature of 210℃-230℃ for 1-3 hours. After cooling and depressurization, the scale inhibitor and dispersant treated at the preset temperature and pressure is obtained. More preferably, it is maintained at a pressure of 4.5 MPa and a temperature of 220℃ for 2 hours.

[0027] In this embodiment, preparing a first blank sample based on coal gasification ash water, borax buffer solution, and sodium bicarbonate solution may include: sequentially adding coal gasification ash water, borax buffer solution, and sodium bicarbonate solution to a volumetric flask, and then adding water to bring the volume to the mark. Preparing a first test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution may include: sequentially adding coal gasification ash water, the scale inhibitor / dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution to a volumetric flask, and then adding water to bring the volume to the mark. Preparing a second test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated after pre-temperature and pressure treatment, borax buffer solution, and sodium bicarbonate solution may include: sequentially adding coal gasification ash water, the scale inhibitor / dispersant to be evaluated after pre-temperature and pressure treatment, borax buffer solution, and sodium bicarbonate solution to a volumetric flask, and then adding water to bring the volume to the mark.

[0028] In the process of preparing the first blank sample, the first test sample, and the second test sample, borax buffer solution is added to provide a stable alkaline environment, maintain the pH value of the reaction system, promote the decomposition of calcium bicarbonate (Ca(HCO3)2) into calcium carbonate (CaCO3) during the subsequent precipitation process, thereby simulating the calcium carbonate deposition process in coal gasification ash water and ensuring the reproducibility and stability of the experimental results.

[0029] During the preparation of the first blank sample, the first test sample, and the second test sample, when adding sodium bicarbonate solution, the amount of calcium ions (Ca) in the coal gasification ash water can be determined based on the specific conditions. 2+ The amount of sodium bicarbonate solution to be added is determined by the content of bicarbonate ions (HCO3-). - ) and calcium ions in coal gasification ash water form Ca 2+ :HCO3 - A molar ratio of 1:(2.8~3.2) is preferred for forming Ca.2+ :HCO3 - A molar ratio of 1:3.05 was used to simulate calcium carbonate deposition conditions in a coal gasification system. Under these molar ratio conditions, a sufficient amount of bicarbonate ions can be decomposed to form calcium carbonate precipitate under heating conditions, allowing for a more accurate evaluation of scale inhibition performance.

[0030] During the preparation of the first and second test samples, when adding the scale inhibitor and dispersant to be evaluated, the amount of scale inhibitor and dispersant to be evaluated can be determined based on the actual amount of scale inhibitor and dispersant added during the operation of the coal gasification system.

[0031] In a specific example, the preparation process of the first blank sample, the first test sample, and the second test sample is as follows: 1 L of the scale inhibitor / dispersant to be evaluated is placed in a high-temperature, high-pressure reactor to simulate the working conditions of a coal gasification system. After maintaining the reactor at a pressure of 4.5 MPa and a temperature of 220 °C for 2 hours, the pressure and temperature are reduced to obtain the scale inhibitor / dispersant to be evaluated after high-temperature, high-pressure treatment. 250 mL of coal gasification ash water is added to a 500 mL volumetric flask, followed by 25 mL of borax buffer solution, and then sodium bicarbonate solution is added to bring the added bicarbonate ion concentration to 366 mg. The volume is then adjusted to 500 mL to obtain the first blank sample. 250 mL of coal gasification ash water and 60 ppm of the scale inhibitor / dispersant to be evaluated (without high-temperature, high-pressure treatment) are added to a 500 mL volumetric flask. After mixing thoroughly, 25 mL of borax buffer solution is added, followed by sodium bicarbonate solution to bring the added bicarbonate ion concentration to 366 mg. The volume is then adjusted to 500 mL to obtain the first test sample. Add 250 mL of coal gasification ash water and 60 ppm of the scale inhibitor and dispersant to be evaluated after high temperature and high pressure treatment to a 500 mL volumetric flask. After mixing evenly, add 25 mL of borax buffer solution, followed by sodium bicarbonate solution to make the amount of added bicarbonate ions 366 mg. Finally, make up to 500 mL to obtain the second test sample.

[0032] In this embodiment of the application, the heating treatment of the first blank sample, the first test sample, and the second test sample may include: placing the first blank sample, the first test sample, and the second test sample in a constant temperature water bath and maintaining them at 75℃-85℃ for 10h-18h. More preferably, placing the first blank sample, the first test sample, and the second test sample in a constant temperature water bath and maintaining them at 80℃ for 16h.

[0033] During the above-mentioned heat treatment, calcium carbonate precipitate can be generated in the first blank sample, the first test sample, and the second test sample. Filtering the first blank sample, the first test sample, and the second test sample can be used to remove the calcium carbonate precipitate.

[0034] When filtering the first blank sample, the first test sample, and the second test sample, medium-speed filter paper can be used and the filtration should be performed while the sample is still hot. Hot filtration allows the precipitate to be filtered out quickly before its crystal form changes (such as from amorphous to more stable calcite), avoiding the possibility that the precipitate may redissolve or undergo partial morphological changes after cooling, which could affect the accuracy of subsequent measurement results.

[0035] It is understandable that after filtering the first blank sample, the first test sample, and the second test sample, filtrates of the first blank sample, the first test sample, and the second test sample are obtained, respectively. The calcium ions contained in the filtrates are unprecipitated calcium ions. Among the unprecipitated calcium ions in the filtrates of the first and second test samples, some of the calcium ions are those successfully stabilized in the water by the scale inhibitor / dispersant to be evaluated.

[0036] In the embodiments of this application, titrating the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample may include: first diluting the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample, then adding potassium hydroxide solution and calcium carboxylic acid indicator, and titrating with disodium ethylenediaminetetraacetate (EDTA) solution. The titration endpoint is reached when the purple-red color turns into a bright blue color.

[0037] Diluting the filtrate increases its volume, making titration easier and allowing for observation of color changes, thus accurately determining the titration endpoint. It also reduces potential interference from other ions in the filtrate.

[0038] Adding potassium hydroxide solution can provide a strongly alkaline environment (pH≈12-13). Under this environment, the magnesium ions (Mg) in the filtrate... 2+ The calcium ion will be masked by the formation of magnesium hydroxide (Mg(OH)2) precipitate, thus no longer interfering with the titration of calcium ions by EDTA. Furthermore, the complexation reaction between EDTA and calcium ions requires alkaline conditions to proceed completely.

[0039] Calcium carboxylic acid indicator, which is blue in solution, reacts with Ca... 2+ The calcium ions combine to form a purplish-red calcium-indicator complex (Ca-In). EDTA is a stronger complexing agent. When titrating with EDTA solution, EDTA first combines with the free calcium ions in the filtrate. When the free calcium ions in the filtrate are almost completely complexed, if EDTA is added again, EDTA will capture the calcium ions in the calcium-indicator complex to form a more stable, colorless Ca-EDTA complex, releasing the calcium carboxylic acid indicator. The solution color changes from purplish-red to bright blue, indicating that the titration endpoint has been reached.

[0040] Following the example above, the specific process for titrating the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample can be as follows: Taking the filtrate of the first blank sample as an example, after the filtrate of the first blank sample has cooled, transfer 25 mL of the filtrate to a 250 mL Erlenmeyer flask, add 50 mL of distilled water for dilution, then add 7 mL of potassium hydroxide solution (100 g / L) and 0.1 g of calcium carboxylic acid indicator, and titrate with EDTA standard titration solution (concentration of 0.01 mol / L) until the purple-red color changes to bright blue, and record the amount of titrant consumed. The specific process for titrating the filtrate of the first test sample and the filtrate of the first test sample is the same as that for the first blank sample, and will not be repeated here.

[0041] In this embodiment, calculating the first scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the titrant consumption of the filtrate corresponding to the first blank sample and the titrant consumption of the filtrate corresponding to the first test sample, and calculating the second scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the titrant consumption of the filtrate corresponding to the first blank sample and the titrant consumption of the filtrate corresponding to the second test sample, may include: determining the calcium ion concentration in the filtrate of the first blank sample based on the titrant consumption of the filtrate corresponding to the first blank sample, determining the calcium ion concentration in the filtrate of the first test sample based on the titrant consumption of the filtrate corresponding to the first test sample, and determining the calcium ion concentration in the filtrate of the second test sample based on the titrant consumption of the filtrate corresponding to the second test sample; calculating the first scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the first test sample, and calculating the second scale inhibition rate of the scale inhibitor / dispersant to be evaluated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the second test sample.

[0042] The concentration of calcium ions in the filtrate of the first blank sample can be determined based on the amount of titrant consumed corresponding to the filtrate of the first blank sample, which can be done using the following formula (1): (1); In the above formula (1), The concentration of calcium ions in the filtrate of the first blank sample is expressed in mg / mL. This represents the volume of titrant consumed corresponding to the filtrate of the first blank sample, specifically EDTA standard titrant solution, in mL. The concentration of the titrant is expressed in mol / L. This represents the molar mass of calcium, expressed in g / mol. The volume of the filtrate of the first blank sample is in mL. For example, in the process described above, "transfer 25 mL of filtrate to a 250 mL conical flask and add 50 mL of distilled water for dilution", the volume of the filtrate of the first blank sample is 25 mL.

[0043] The concentration of calcium ions in the filtrate of the first test sample can be determined based on the amount of titrant consumed corresponding to the filtrate of the first test sample, using the following formula (2): (2); In the above formula (2), The concentration of calcium ions in the filtrate of the first test sample is expressed in mg / mL. This refers to the volume of titrant consumed corresponding to the filtrate of the first test sample, which can be EDTA standard titrant solution, in mL. The concentration of the titrant is expressed in mol / L. This represents the molar mass of calcium, expressed in g / mol. The volume of the filtrate from the first test sample is in mL.

[0044] The concentration of calcium ions in the filtrate of the second test sample can be determined based on the amount of titrant consumed corresponding to the filtrate of the second test sample, using the following formula (3): (2); In the above formula (2), The concentration of calcium ions in the filtrate of the second test sample is expressed in mg / mL. This refers to the volume of titrant consumed corresponding to the filtrate of the second test sample, which can be EDTA standard titrant solution, in mL. The concentration of the titrant is expressed in mol / L. This represents the molar mass of calcium, expressed in g / mol. This represents the volume of the filtrate from the second test sample, in mL.

[0045] Furthermore, the first scale inhibition rate of the scale inhibitor to be evaluated can be calculated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the first test sample, using the following formula (4). The second scale inhibition rate of the scale inhibitor to be evaluated can be calculated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the second test sample, using the following formula (5). (4); (5); In the above formulas (4) and (5), The first scale inhibition rate of the scale inhibitor / dispersant to be evaluated; The second scale inhibition rate of the scale inhibitor / dispersant to be evaluated; The calcium ion concentration in the first blank sample, the first test sample, or the second test sample before precipitation is considered to be the same. The unit is mg / mL.

[0046] The amount of calcium ions that can theoretically be stabilized (or scale inhibited) without the addition of the scale inhibitor to be evaluated is the amount of calcium carbonate precipitate in the first blank sample. The first test sample had a greater amount of stable (scale-inhibiting) calcium ions than the first blank sample after adding the scale inhibitor and dispersant to be evaluated at room temperature and pressure. To determine the amount of stable (scale-inhibiting) calcium ions in the second test sample compared to the first blank sample after adding the scale inhibitor and dispersant treated under high temperature and high pressure. First scale inhibition rate. This can be understood as the percentage of calcium carbonate precipitation actually inhibited by the scale inhibitor / dispersant under normal temperature and pressure, relative to the theoretically maximum inhibitable calcium carbonate precipitation. A higher percentage indicates better scale inhibition performance. Second scale inhibition rate. This can be understood as the percentage of calcium carbonate precipitation actually inhibited by the scale inhibitor and dispersant under high temperature and high pressure treatment relative to the theoretically maximum amount of calcium carbonate precipitation that can be inhibited. The higher the percentage, the better the scale inhibition performance.

[0047] Step 102: Prepare a second blank sample and a reference sample based on water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin; prepare a test sample based on water, calcium salt solution, the scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin; measure the turbidity of the second blank sample after heating and dispersing treatment; measure the turbidity of the reference sample and the test sample after heating and dispersing treatment and settling treatment; calculate the dispersion performance of the scale inhibitor / dispersant to be evaluated based on the turbidity of the second blank sample, the reference sample, and the test sample.

[0048] That is, the scale inhibitor and dispersant to be evaluated were not added to the second blank sample and the reference sample, while the scale inhibitor and dispersant to be evaluated were added to the test sample, and the composition and content of other components in the three samples were the same.

[0049] In this embodiment, preparing a second blank sample based on water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin may include: sequentially adding water, calcium salt solution, sodium tetraborate solution, and sodium bicarbonate solution to a volumetric flask, adding water to bring the volume to the mark, transferring the solution from the volumetric flask to a mixing container, and then adding kaolin. The process for preparing the reference sample is the same as that for preparing the second blank sample, and will not be described again here. Preparing a test sample based on water, calcium salt solution, scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin may include: sequentially adding water, calcium salt solution, scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, and sodium bicarbonate solution to a volumetric flask, adding water to bring the volume to the mark, transferring the solution from the volumetric flask to a mixing container, and then adding kaolin.

[0050] In the preparation of the second blank sample, reference sample, and test sample, a calcium salt solution is added to provide calcium ions (Ca).2+ Calcium ions are common hardness ions in natural water and industrial circulating water. They readily form scale with carbonate and phosphate ions or interact with suspended particles (such as kaolin), affecting the dispersion of suspended particles. By adding calcium ions, the hardness conditions of actual water bodies can be simulated, allowing for the testing of the scale inhibitor / dispersant's dispersion performance in high-hardness water. This more accurately reflects the scale inhibitor / dispersant's resistance to calcium interference and its dispersion effect.

[0051] In specific operations, the calcium salt solution can be selected from calcium chloride standard solution, calcium nitrate standard solution, calcium sulfate saturated solution or other soluble calcium salt standard solution, with calcium chloride standard solution being more preferred.

[0052] Adding sodium tetraborate solution during the preparation of the second blank sample, reference sample, and test sample serves three main purposes. First, it provides a stable, slightly alkaline environment (pH ≈ 8.0) close to the common operating conditions of industrial circulating cooling water. To prevent equipment corrosion, industrial circulating cooling water typically operates under slightly alkaline conditions. Adjusting the pH to around 8.0 allows the experimental results to more accurately reflect the performance of the scale inhibitor / dispersant being evaluated in practical applications. Second, it provides a buffer system. Sodium tetraborate (Na2B4O7) is a good buffer that can resist drastic pH changes caused by the subsequent addition of sodium bicarbonate or small amounts of acidic / alkaline substances that may be generated during the experiment. This ensures that the pH environment remains stable throughout the experiment (especially during the settling phase of the test and reference samples), thereby guaranteeing the reproducibility and comparability of the experimental results. Third, it helps control the scaling tendency. pH directly affects the solubility of calcium carbonate. Adjusting the pH to around 8.0 allows bicarbonate ions to have a sufficient tendency to convert into carbonate ions and combine with calcium ions (i.e., to form scale), but also prevents the reaction from happening too quickly. This allows for a more accurate determination of whether the scale inhibitor / dispersant being evaluated can inhibit scale formation and disperse suspended particles.

[0053] Sodium bicarbonate solution is added during the preparation of the second blank sample, reference sample, and test sample. Firstly, it provides scale-forming anions. Bicarbonate (HCO3-) 3- CO32 is the most common scale-forming anion in water. Under heating and weakly alkaline conditions, it decomposes to produce carbonate ions (CO32-). 2-The calcium carbonate ions combine with the previously added calcium ions to form calcium carbonate microcrystals or precipitates. Secondly, it can simulate the alkalinity of water, inducing the formation of calcium carbonate scale. Alkalinity is an important characteristic of water, representing its ability to accept protons. Adding bicarbonate ions can standardize the alkalinity of the system, ensuring that the alkalinity conditions are the same for each experiment, thus making the test results comparable. Thirdly, it can provide a supersaturated system. By providing excess calcium ions and bicarbonate ions, the system is in a supersaturated state, exhibiting a strong tendency to scale. Excellent scale inhibitors and dispersants often need to be able to inhibit the growth and deposition of these microcrystals (scale inhibition effect) and disperse already formed small scale particles and kaolin particles, preventing them from agglomerating and settling. Therefore, the dispersion performance of the scale inhibitors and dispersants to be evaluated can be more accurately assessed.

[0054] Kaolin was added during the preparation of the second blank sample, reference sample, and test sample. Firstly, it can simulate suspended matter in real water systems. In real industrial circulating cooling water, boiler water, or other water systems, various suspended particles inevitably exist, such as silt, clay, corrosion products (e.g., iron oxide particles), microbial communities and their metabolites, and other insoluble impurities. Kaolin is a natural clay mineral with relatively stable composition and particle size, and its properties are very similar to the aforementioned common suspended particles; therefore, it is used to represent and simulate suspended substances in water systems that need to be dispersed to prevent sedimentation. Secondly, it can serve as an "indicator" and "measuring scale" for dispersion effectiveness. Kaolin itself is an insoluble solid particle that naturally settles in water, leading to a decrease in turbidity. The better the dispersion performance of the scale inhibitor / dispersant, the more effectively it can divide, encapsulate, and adsorb kaolin particles, maintaining them in a dispersed and suspended state through electrostatic repulsion or steric hindrance effects, thereby slowing down or preventing sedimentation. Therefore, higher turbidity means more kaolin particles suspended in the solution, indicating better dispersion performance of the scale inhibitor / dispersant. If kaolin is not added, and the dispersion performance of the scale inhibitor / dispersant is evaluated solely by the trace amounts of calcium carbonate scale formed by calcium ions and bicarbonate ions, the turbidity signal generated is very weak due to the small number and fineness of the calcium carbonate scale particles, making it difficult to accurately measure and distinguish differences in the dispersion performance of the scale inhibitor / dispersant. Adding kaolin provides a strengthened, measurable turbidity signal, making the differences in dispersion effects obvious and quantifiable. Thirdly, it provides a unified testing standard. The composition, particle size, and shape of sludge or corrosion products from different sources vary greatly, leading to inconsistent and uncomparable experimental results. Kaolin's properties (such as particle size distribution and purity) are relatively stable and it can be commercially standardized for production; using kaolin ensures comparability of test results.

[0055] During the preparation of test samples, when adding the scale inhibitor and dispersant to be evaluated, the amount of scale inhibitor and dispersant to be evaluated can be determined based on the actual amount of scale inhibitor and dispersant added during the operation of the coal gasification system.

[0056] In a specific example, the preparation process for the second blank sample, reference sample, and test sample is as follows: Add 150 mL of distilled water to a 250 mL volumetric flask, and add calcium chloride standard solution to make the calcium ion addition 20 mg. After mixing thoroughly, add sodium tetraborate solution to the volumetric flask to adjust the pH to approximately 8.0. Then, add sodium bicarbonate solution to the volumetric flask to make the bicarbonate addition 61 mg. Add distilled water to bring the volume to 250 mL. Then, transfer the solution from the volumetric flask to a beaker and add 0.25 g of kaolin. Stir thoroughly to obtain the second blank sample. The preparation process for the reference sample is the same as that for the second blank sample and will not be repeated here. Add 150 mL of distilled water to a 250 mL volumetric flask, and add calcium chloride standard solution to make the calcium ion addition amount 20 mg. Then add 60 ppm of the scale inhibitor and dispersant to be evaluated to the volumetric flask, mix well, and then add sodium tetraborate solution to adjust the pH value to about 8.0. Continue to add sodium bicarbonate solution to the volumetric flask to make the bicarbonate addition amount 61 mg. Add distilled water to make up to 250 mL, then transfer the solution in the volumetric flask to a beaker and add 0.25 g of kaolin. Stir well to obtain the test sample.

[0057] In this embodiment, the heating and dispersion treatment of the second blank sample may include: ultrasonically vibrating the second blank sample at 39℃-41℃ for 18min-22min. The heating and dispersion treatment and settling treatment of the reference sample and test sample may include: ultrasonically vibrating the reference sample and test sample at 39℃-41℃ for 18min-22min, and then settling the reference sample and test sample at 39℃-41℃ for 4h-6h.

[0058] The 39℃-41℃ temperature range simulates real-world operating conditions, ensuring that subsequent test results more accurately reflect the true dispersion effect of the scale inhibitor / dispersant being evaluated. A 4-6 hour settling period provides sufficient reaction time. Scale formation (the formation and growth of calcium carbonate microcrystals) and particle sedimentation are relatively slow processes. This 4-6 hour settling time allows ample conditions for these physicochemical processes to occur, enabling calcium ions and bicarbonate ions to form calcium carbonate microcrystals and allowing kaolin particles time to exhibit dispersion or sedimentation trends under the influence of the scale inhibitor / dispersant being evaluated. This results in a more accurate reflection of the scale inhibitor / dispersant's dispersion performance. A 4-6 hour settling period at 39℃-41℃ can be considered an accelerated test. By appropriately increasing the temperature and extending the settling time, the deposition process can be accelerated, significantly amplifying the differences in dispersion performance between different scale inhibitors / dispersants being evaluated within a short time, facilitating rapid evaluation and comparison.

[0059] Following the example above, the specific process for heating and dispersing the second blank sample can be as follows: The second blank sample is ultrasonically vibrated at 40℃ for 20 minutes. After stirring, 40 mL of the turbid liquid is transferred from a 200 mL container. The transferred turbid liquid is then ultrasonically vibrated at 40℃ for 10 minutes, and the turbidity is measured. The specific process for heating and dispersing the reference sample and allowing it to stand is as follows: The reference sample is ultrasonically vibrated at 40℃ for 20 minutes, then allowed to stand at 40℃ for 5 hours. After stirring, 40 mL of the turbid liquid is transferred from a 200 mL container. The transferred turbid liquid is then ultrasonically vibrated at 40℃ for 10 minutes, and the turbidity is measured. The specific process for heating and dispersing the test sample and allowing it to stand is the same as that for the reference sample, and will not be repeated here.

[0060] By sampling in the upper and middle sections and then ultrasonically vibrating the liquid before turbidity testing, it is ensured that the turbidity measurement reflects truly dispersed particles, rather than large, randomly suspended aggregates. During settling, large, heavy particles preferentially settle to the bottom of the graduated cylinder, while the upper and middle sections mainly contain effectively dispersed fine particles or particles suspended due to Brownian motion. Sampling at the bottom would yield a large number of settled particles, failing to accurately reflect the dispersion effect; similarly, sampling at the top would result in too low a particle concentration, also failing to accurately reflect the dispersion effect. Ultrasonic vibration can break up weak, physically dispersed aggregates, allowing measurement only of chemically stable dispersed particles. After settling, some particles may temporarily aggregate not due to deposition, but due to weak van der Waals forces. Such aggregates are unstable, and ultrasound can break them up. Highly effective scale inhibitors and dispersants tightly coat the particle surface through chemical bonds (such as adsorption), providing strong electrostatic repulsion or steric hindrance. This chemical dispersion resists the impact of ultrasound. Therefore, the turbidity measured after ultrasonic treatment represents the amount of particles that are truly and stably dispersed by the scale inhibitor and dispersant, eliminating the interference of physical agglomeration, and the result is more reliable.

[0061] In this embodiment of the application, the dispersion performance of the scale inhibitor to be evaluated is calculated based on the turbidity of the second blank sample, the reference sample, and the test sample, which can be done based on the following formula (6): (6); In the above formula (6), The dispersion performance of the scale inhibitor / dispersant to be evaluated; The turbidity of the test sample; The turbidity of the reference sample; The turbidity of the second blank sample.

[0062] Among them, the turbidity of the reference sample This reflects the background turbidity after the particles have naturally settled in the absence of the scale inhibitor / dispersant being evaluated. This value is usually low because most particles have settled. (The turbidity of the test sample is also mentioned.) This value reflects how many particles remain suspended after the same standing time, even after adding the scale inhibitor / dispersant being evaluated. A higher value indicates a better dispersion effect of the scale inhibitor / dispersant. The turbidity of the second blank sample... This reflects the initial total amount of particles. The above formula (6) is obtained by subtracting the background turbidity after natural settling of particles from the turbidity of the test sample, and then dividing by the maximum turbidity theoretically achievable through dispersion. This can accurately reflect the dispersion performance of the scale inhibitor / dispersant being evaluated.

[0063] Step 103: Prepare a test sample based on the scale inhibitor and dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution, ammonium molybdate solution and ascorbic acid solution, and measure the absorbance. Calculate the phosphorus content of the scale inhibitor and dispersant to be evaluated based on the absorbance.

[0064] In this embodiment of the application, the preparation of the test sample based on the scale inhibitor and dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution, ammonium molybdate solution and ascorbic acid solution may include: mixing the scale inhibitor and dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution and water, heating the mixture for a preset time and then adding ammonium molybdate solution and ascorbic acid solution, and further diluting to obtain the test sample.

[0065] The addition of sulfuric acid solution provides an acidic environment, promoting hydrolysis and oxidation reactions. This allows the polyphosphates and organophosphate compounds in the scale inhibitor / dispersant being evaluated to be completely decomposed and converted into orthophosphates (PO4) under acidic conditions through the strong oxidizing effect of potassium persulfate. 3- Potassium persulfate, as an oxidizing agent, can decompose organic matter and polyphosphate under heating conditions, converting them into measurable orthophosphate ions.

[0066] Ammonium molybdate can react with converted orthophosphate to form yellow phosphomolybdic heteropolyacid. Ascorbic acid can reduce phosphomolybdic heteropolyacid to blue phosphomolybdic blue complex, enhancing absorbance so that absorbance can be measured by spectrophotometry.

[0067] In a specific example, the preparation process of the test sample is as follows: A certain mass of the scale inhibitor / dispersant to be evaluated is transferred into a beaker, followed by 1 mL of sulfuric acid solution (1 volume of concentrated sulfuric acid + 35 volumes of water) and 5 mL of potassium persulfate solution (40 g / L). Distilled water is added to approximately 40 mL, and the mixture is placed on an electric furnace and kept at a gentle boil for about 30 minutes. Water is added periodically to maintain the solution volume at 25 mL-30 mL. After cooling, the entire volume is transferred to a 50 mL volumetric flask, and then 2 mL of ammonium molybdate solution and 3 mL of ascorbic acid solution are added. The mixture is diluted with water to the mark and shaken well. It is then left to stand at room temperature for 10 minutes. Standing at room temperature for 10 minutes ensures complete colorimetric reaction and color stability.

[0068] In this embodiment of the application, measuring absorbance may include: measuring absorbance at a wavelength of 710 nm using a spectrophotometer.

[0069] Furthermore, calculating the phosphorus content of the scale inhibitor / dispersant to be evaluated based on absorbance can include: determining the phosphorus content of the scale inhibitor / dispersant to be evaluated based on the absorbance of the sample and the correlation between phosphorus content and absorbance. Specifically, a standard curve can be plotted with phosphate mass on the x-axis and absorbance on the y-axis, and then a regression equation can be fitted to obtain the correlation between phosphorus content and absorbance.

[0070] Step 104: Calculate the score of the scale inhibitor / dispersant to be evaluated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

[0071] In this embodiment of the application, the score of the scale inhibitor / dispersant to be evaluated is calculated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content. This may include steps one and two, as follows: Step 1: Normalize the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

[0072] Since higher values ​​for the first scale inhibition rate, second scale inhibition rate, and dispersion performance all indicate better performance of the scale inhibitor / dispersant being evaluated, these three metrics can be classified as positive indicators. Conversely, phosphorus content relates to environmental friendliness in emissions, and lower values ​​are better; therefore, phosphorus content can be classified as a negative indicator.

[0073] For positive indicators (first scale inhibition rate, second scale inhibition rate, and dispersion performance), normalization can be performed based on the following formula (7): Score_X i = (X i -X min )×100 / (X max -X min (7); In the above formula (7), Score_X iThe results of normalization treatment are the first scale inhibition rate, second scale inhibition rate, or dispersion performance of the scale inhibitor / dispersant to be evaluated; X i X represents the first scale inhibition rate, second scale inhibition rate, or dispersion performance of the scale inhibitor / dispersant to be evaluated. max X represents the maximum first scale inhibition rate, the maximum second scale inhibition rate, or the maximum dispersion performance. min The minimum first scale inhibition rate, minimum second scale inhibition rate, or minimum dispersion performance.

[0074] In practical applications, multiple scale inhibitors and dispersants to be evaluated can be tested for first scale inhibition rate, second scale inhibition rate, and dispersion performance, resulting in multiple first scale inhibition rates, multiple second scale inhibition rates, and multiple dispersion performances. The maximum first scale inhibition rate is the maximum value among the multiple first scale inhibition rates, and the minimum first scale inhibition rate is the minimum value among the multiple first scale inhibition rates. Similarly, the maximum second scale inhibition rate is the maximum value among the multiple second scale inhibition rates, and the minimum second scale inhibition rate is the minimum value among the multiple second scale inhibition rates. The maximum dispersion performance is the maximum value among the multiple dispersion performances, and the minimum second scale inhibition rate is the minimum value among the multiple dispersion performances.

[0075] For negative indicators (phosphorus content), normalization can be performed based on the following formula (8): Score_X i = (X max -X i )×100 / (X max -X min (8); In the above formula (8), Score_X i The result is the normalized phosphorus content of the scale inhibitor / dispersant to be evaluated; X i The phosphorus content of the scale inhibitor / dispersant to be evaluated; X max Maximum phosphorus content; X min This is the minimum phosphorus content.

[0076] Similarly, the phosphorus content can be tested for multiple scale inhibitors and dispersants to be evaluated, resulting in multiple phosphorus contents; the maximum phosphorus content is the highest value among the multiple phosphorus contents, and the minimum phosphorus content is the lowest value among the multiple phosphorus contents.

[0077] Step 2: Calculate the score of the scale inhibitor / dispersant to be evaluated based on the normalized results of the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content, as well as the preset weights of the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

[0078] Specifically, the score of the scale inhibitor / dispersant to be evaluated can be calculated based on the following formula (9): Final Score=(Score_X1×W1)+(Score_X2×W2)+(Score_X3×W3)+(Score_X4×W4)(9); In the above formula (9), Final Score is the score of the scale inhibitor / dispersant to be evaluated, and the higher the score, the better the performance; Score_X1 is the result of the first scale inhibition rate of the scale inhibitor / dispersant to be evaluated after normalization treatment; W1 is the preset weight of the first scale inhibition rate; Score_X2 is the result of the second scale inhibition rate of the scale inhibitor / dispersant to be evaluated after normalization treatment; W2 is the preset weight of the second scale inhibition rate; Score_X3 is the result of the dispersion performance of the scale inhibitor / dispersant to be evaluated after normalization treatment; W3 is the preset weight of the dispersion performance; Score_X4 is the result of the phosphorus content of the scale inhibitor / dispersant to be evaluated after normalization treatment; W4 is the preset weight of the phosphorus content.

[0079] In practical applications, for coal gasification ash water, the first scale inhibition rate is the basic performance, the second scale inhibition rate is more critical, the dispersion performance is crucial to prevent soft scale, and the phosphorus content can be regarded as an environmental protection indicator. Therefore, in accordance with the coal gasification ash water being treated, the preset weight of the first scale inhibition rate can be set to 0.2, the preset weight of the second scale inhibition rate to 0.35, the preset weight of the dispersion performance to 0.3, and the preset weight of the phosphorus content to 0.15.

[0080] It is understood that the performance evaluation method for scale inhibitors and dispersants in coal gasification ash water provided in this application includes: preparing a first blank sample based on coal gasification ash water, borax buffer solution, and sodium bicarbonate solution; preparing a first test sample based on coal gasification ash water, the scale inhibitor and dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution; and preparing a second test sample based on coal gasification ash water, the scale inhibitor and dispersant to be evaluated after pre-temperature and pressure treatment, borax buffer solution, and sodium bicarbonate solution; filtering the first blank sample, the first test sample, and the second test sample after heat treatment; titrating the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample; calculating the first scale inhibition rate of the scale inhibitor and dispersant to be evaluated based on the titrant consumption of the filtrate of the first blank sample and the titrant consumption of the filtrate of the first test sample; and calculating the first scale inhibition rate of the scale inhibitor and dispersant to be evaluated based on the titrant consumption of the filtrate of the first blank sample and the second test sample. The second scale inhibition rate of the scale inhibitor / dispersant to be evaluated is calculated based on the titrant consumption corresponding to the filtrate of the test sample. A second blank sample and a reference sample are prepared using water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. A test sample is prepared using water, calcium salt solution, the scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. The turbidity of the second blank sample is measured after heating and dispersion treatment. The turbidity of the reference sample and the test sample is measured after heating, dispersion treatment, and settling treatment. The dispersion performance of the scale inhibitor / dispersant to be evaluated is calculated based on the turbidity of the second blank sample, reference sample, and test sample. A test sample is prepared using the scale inhibitor / dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution, ammonium molybdate solution, and ascorbic acid solution, and its absorbance is measured. The phosphorus content of the scale inhibitor / dispersant to be evaluated is calculated based on the absorbance. The score of the scale inhibitor / dispersant to be evaluated is calculated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content. The solution provided in this application takes into account multiple aspects when evaluating the performance of scale inhibitors and dispersants in coal gasification ash water, including scale inhibition rate, dispersion performance, and phosphorus content, making the evaluation more comprehensive and enabling a more accurate evaluation of the performance of scale inhibitors and dispersants in coal gasification ash water.

[0081] It is understandable that by evaluating the performance of scale inhibitors and dispersants in coal gasification ash water and calculating their scores, a more ideal scale inhibitor and dispersant can be selected, or the formulation of the scale inhibitor and dispersant can be optimized based on the evaluation results.

[0082] Taking the optimization of the formulation of scale inhibitors and dispersants for coal gasification ash water as an example, the optimization rule is: the controlled variable method, fixing all other conditions and the proportions of other components in the formulation, and only changing one target variable (such as temperature, hardness, pH, or the dosage of a single agent). The formulation is optimized by comparing the scale inhibition rate under different variables. For example, a certain formulation has a scale inhibition rate of 95% at 60℃, but drops to 80% at 80℃, indicating that the high-temperature stability of the formulation is insufficient. Optimization directions could include: increasing the proportion of high-temperature resistant single agents (such as introducing dispersants with better high-temperature stability, such as sulfonic acid group copolymers or phosphonocarboxylic acids), or adjusting the ratio of corrosion inhibitors to dispersants to cope with the more severe deposition tendency at high temperatures.

[0083] The solution provided in this application will be described below with reference to specific embodiments. It should be understood that the following embodiments are only specific implementation methods and do not imply improper limitation on the solution of this application.

[0084] For scale inhibitors 1, 2, 3, 4, and 5, tests were conducted on their first scale inhibition rate (i.e., scale inhibition rate at room temperature and pressure), second scale inhibition rate (i.e., scale inhibition rate at high temperature and pressure, specifically resistance to 220℃), dispersibility, and phosphorus content. The dosage of each scale inhibitor was 60 ppm, and the experimental conditions were identical for each test. The test results are shown in Table 1. Table 1 Test Results

[0085] The scale inhibitor and dispersant 1 has the following normalized results for scale inhibition rate at room temperature and pressure (S1), scale inhibition rate at high temperature and pressure (S2), dispersion performance (S3), phosphorus content (S4), and evaluation scores: S1= (78.9 - 78.08)×100 / (82.5 - 78.08) =18.55; S2= (52.6 - 52.6)×100 / (61.6 - 52.6) =0.00; S3= (1.50 - 0.90)×100 / (20.02 - 0.90) = 3.14; S4= (7.24 - 4.86)×100 / (7.24 - 2.86) = 54.34; Final Score=(18.55×0.20) + (0.00×0.35) + (3.14×0.30) + (54.34×0.15) =12.80.

[0086] The scale inhibitor and dispersant 2 has the following results: normalized scale inhibition rate at room temperature and pressure (S1), normalized scale inhibition rate at high temperature and pressure (S2), normalized dispersibility (S3), normalized phosphorus content (S4), and evaluation scores: S1= (79.2 - 78.08)×100 / (82.5 - 78.08) =25.34; S2= (55.5 - 52.6)×100 / (61.6 - 52.6) =32.22; S3= (0.90 - 0.90)×100 / (20.02 - 0.90) =0.00; S4= (7.24 - 4.89)×100 / (7.24 - 2.86) = 53.65; Final Score=(25.34×0.20) + (32.22×0.35) + (0.00×0.30) + (53.65×0.15) = 24.40.

[0087] The scale inhibitor and dispersant 3 has the following results: normalized scale inhibition rate at room temperature and pressure (S1), normalized scale inhibition rate at high temperature and pressure (S2), normalized dispersibility (S3), normalized phosphorus content (S4), and evaluation scores: S1= (80.9 - 78.08)×100 / (82.5 - 78.08)=63.80; S2= (55.0 - 52.6)×100 / (61.6 - 52.6) =26.67; S3= (20.02 - 0.90)×100 / (20.02 - 0.90) =100.00; S4= (7.24 - 2.86)×100 / (7.24 - 2.86) =100.00; Final Score=(63.80×0.20) + (26.67×0.35) + (100.00×0.30) + (100.00×0.15) = 67.09.

[0088] The scale inhibitor and dispersant 4 has the following results: normalized scale inhibition rate at room temperature and pressure (S1), normalized scale inhibition rate at high temperature and pressure (S2), normalized dispersibility (S3), normalized phosphorus content (S4), and evaluation scores: S1= (82.5 - 78.08)×100 / (82.5 - 78.08) =100.00; S2= (61.6 - 52.6)×100 / (61.6 - 52.6) =100.00; S3= (19.91 - 0.90)×100 / (20.02 - 0.90) =99.42; S4= (7.24 - 2.92)×100 / (7.24 - 2.86) =98.63; Final Score=(100.00×0.20) + (100.00×0.35) + (99.42×0.30) + (98.63×0.15) =99.62.

[0089] The scale inhibitor and dispersant 5 has the following results: normalized scale inhibition rate at room temperature and pressure (S1), normalized scale inhibition rate at high temperature and pressure (S2), normalized dispersibility (S3), normalized phosphorus content (S4), and evaluation scores: S1= (78.08 - 78.08)×100 / (82.5 - 78.08) =0.00; S2= (60.21 - 52.6)×100 / (61.6 - 52.6) =84.56; S3= (15.55 - 0.90)×100 / (20.02 - 0.90)=76.62; S4= (7.24 - 7.24)×100 / (7.24 - 2.86) =0.00; Final Score=(0.00×0.20) + (84.56×0.35) + (76.62×0.30) + (0.00×0.15) = 52.59.

[0090] Based on the scores of each scale inhibitor and dispersant, scale inhibitor and dispersant 4 has the best performance.

[0091] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0092] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for evaluating the performance of scale inhibitors and dispersants in coal gasification ash water, characterized in that, The evaluation method includes: preparing a first blank sample based on coal gasification ash water, borax buffer solution, and sodium bicarbonate solution; preparing a first test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution; and preparing a second test sample based on coal gasification ash water, the scale inhibitor / dispersant to be evaluated treated at a preset temperature and pressure, borax buffer solution, and sodium bicarbonate solution. The first blank sample, the first test sample, and the second test sample are heated and then filtered. The filtrates from the first blank sample, the first test sample, and the first test sample are titrated. The amount of titrant consumed corresponding to the filtrate of the first blank sample and the first test sample is calculated based on the amount of titrant consumed. The scale inhibition rate of the scale inhibitor and dispersant to be evaluated was determined, and the second scale inhibition rate was calculated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the second test sample. A second blank sample and a reference sample were prepared using water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. A test sample was prepared using water, calcium salt solution, the scale inhibitor and dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin. The turbidity of the second blank sample was measured after heating and dispersion treatment. The turbidity of the reference sample and the test sample was measured after heating and dispersion treatment and settling treatment. The dispersion performance of the scale inhibitor and dispersant to be evaluated was calculated based on the turbidity of the second blank sample, the reference sample, and the test sample. The test sample was prepared based on the scale inhibitor and dispersant to be evaluated, sulfuric acid solution, potassium persulfate solution, ammonium molybdate solution and ascorbic acid solution, and the absorbance was measured. The phosphorus content of the scale inhibitor and dispersant to be evaluated was calculated based on the absorbance. The score of the scale inhibitor / dispersant to be evaluated is calculated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

2. The method for evaluating the performance of scale inhibitors and dispersants in coal gasification ash water according to claim 1, characterized in that, The scale inhibitor / dispersant to be evaluated after pre-temperature and pressure treatment is obtained through the following process: The scale inhibitor and dispersant to be evaluated was placed in a reactor and kept at a pressure of 4.4MPa-4.6MPa and a temperature of 210℃-230℃ for 1-3 hours, and then the temperature and pressure were reduced.

3. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The preparation of the first blank sample based on coal gasification ash water, borax buffer solution and sodium bicarbonate solution includes: adding coal gasification ash water, borax buffer solution and sodium bicarbonate solution to a volumetric flask in sequence, and then adding water to make up to the volume mark of the volumetric flask. The preparation of the first test sample based on coal gasification ash water, the scale inhibitor and dispersant to be evaluated, borax buffer solution, and sodium bicarbonate solution includes: Add coal gasification ash water, scale inhibitor and dispersant to be evaluated, borax buffer solution and sodium bicarbonate solution to the volumetric flask in sequence, and then add water to make up to the volume mark of the volumetric flask. The preparation of the second test sample based on coal gasification ash water, a scale inhibitor / dispersant to be evaluated after pre-treated at a preset temperature and pressure, borax buffer solution, and sodium bicarbonate solution includes: Add coal gasification ash water, the scale inhibitor and dispersant to be evaluated after pre-temperature and pressure treatment, borax buffer solution, and sodium bicarbonate solution to the volumetric flask in sequence, and then add water to make up to the volume mark of the volumetric flask.

4. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 3, characterized in that, During the preparation of the first blank sample, the first test sample, and the second test sample, when adding sodium bicarbonate solution, the molar ratio of added bicarbonate ions to calcium ions in coal gasification ash water was controlled to be 1:(2.8~3.2).

5. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The titration of the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample includes: First, dilute the filtrate of the first blank sample, the filtrate of the first test sample, and the filtrate of the first test sample. Then, add potassium hydroxide solution and calcium carboxylic acid indicator, and titrate with disodium ethylenediaminetetraacetate solution.

6. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The step of calculating the first scale inhibition rate of the scale inhibitor-dispersant to be evaluated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the first test sample, and calculating the second scale inhibition rate of the scale inhibitor-dispersant to be evaluated based on the titrant consumption corresponding to the filtrate of the first blank sample and the titrant consumption corresponding to the filtrate of the second test sample, includes: The calcium ion concentration in the filtrate of the first blank sample is determined based on the amount of titrant consumed corresponding to the filtrate of the first test sample, the calcium ion concentration in the filtrate of the first test sample is determined based on the amount of titrant consumed corresponding to the filtrate of the first test sample, and the calcium ion concentration in the filtrate of the second test sample is determined based on the amount of titrant consumed corresponding to the filtrate of the second test sample. The first scale inhibition rate of the scale inhibitor to be evaluated is calculated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the first test sample, and the second scale inhibition rate of the scale inhibitor to be evaluated is calculated based on the calcium ion concentration in the filtrate of the first blank sample and the calcium ion concentration in the filtrate of the second test sample.

7. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The preparation of the second blank sample and reference sample based on water, calcium salt solution, sodium tetraborate solution, sodium bicarbonate solution, and kaolin includes: Add water, calcium salt solution, sodium tetraborate solution and sodium bicarbonate solution to the volumetric flask in sequence, and dilute with water to the volume mark of the volumetric flask. Transfer the solution in the volumetric flask to a mixing container, and then add kaolin. The test sample, prepared based on water, calcium salt solution, scale inhibitor / dispersant to be evaluated, sodium tetraborate solution, sodium bicarbonate solution, and kaolin, includes: Add water, calcium salt solution, scale inhibitor and dispersant to be evaluated, sodium tetraborate solution and sodium bicarbonate solution to the volumetric flask in sequence, and add water to make up to the volume mark of the volumetric flask. Transfer the solution in the volumetric flask to a mixing container, and then add kaolin.

8. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The heating and dispersion treatment of the second blank sample includes: The second blank sample was ultrasonically vibrated at 39℃-41℃ for 18-22 minutes. The process of heating and dispersing the reference sample and the test sample, followed by a settling process, includes: The reference sample and the test sample were ultrasonically vibrated at 39℃-41℃ for 18min-22min, and then left to stand at 39℃-41℃ for 4h-6h.

9. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The dispersion performance of the scale inhibitor / dispersant to be evaluated is calculated based on the following formula; ; in, The dispersion performance of the scale inhibitor / dispersant to be evaluated; The turbidity of the test sample; The turbidity of the reference sample; The turbidity of the second blank sample.

10. The method for evaluating the performance of the scale inhibitor and dispersant in coal gasification ash water according to claim 1, characterized in that, The score of the scale inhibitor / dispersant to be evaluated is calculated based on the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content, including: The first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content were normalized. The score of the scale inhibitor / dispersant to be evaluated is calculated based on the normalized results of the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content, as well as the preset weights of the first scale inhibition rate, the second scale inhibition rate, the dispersion performance, and the phosphorus content.

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