High calcium magnesium water quality antifouling agent and preparation method thereof

Abstract

This invention relates to the field of oilfield water treatment technology, and discloses a scale inhibitor for high-calcium and magnesium water and its preparation method. The scale inhibitor, by weight, is composed of polyepoxysuccinic acid, organic amine chelating agent, amino acid-modified polyaspartic acid, succinic acid ester, nonionic surfactant, pH adjuster, and deionized water. This invention is phosphorus-free and environmentally friendly, eliminating traditional phosphorus-containing components and avoiding the risk of eutrophication. Through the synergistic effect of multiple components, it possesses strong chelating, lattice distortion, and dispersing properties, exhibiting excellent scale inhibition rates for calcium carbonate and magnesium carbonate scale in high-calcium and magnesium oilfield reinjection water. It also has good corrosion inhibition and storage stability, solving the problems of poor resistance to high hardness and limited performance of traditional agents. It is suitable for scale prevention treatment of high-calcium and magnesium water in oilfields and industries.

Description

Technical Field

[0001] This invention relates to the field of oilfield water treatment technology, specifically to a scale inhibitor for high-calcium and magnesium water and its preparation method. Background Technology

[0002] High-calcium and magnesium water is widely found in groundwater, industrial circulating cooling water, boiler feedwater, oilfield reinjection water, and other applications. The calcium content in this water is high. 2+ Mg 2+ Total hardness often exceeds 1000 mg / L. When the temperature rises, the concentration factor increases, or the pH fluctuates, it readily combines with carbonate and hydroxide ions in the water to form insoluble scale such as calcium carbonate, magnesium carbonate, and magnesium hydroxide. This scale adheres to the inner walls of pipes, heat exchangers, and boilers, significantly reducing heat exchange efficiency, increasing equipment energy consumption, and even causing pipe blockages and equipment corrosion perforation, seriously affecting the safe and stable operation of industrial equipment.

[0003] Currently, scale inhibitors on the market are mainly divided into two categories: phosphorus-containing scale inhibitors and phosphorus-free scale inhibitors. While phosphorus-containing scale inhibitors have good scale inhibition effects, phosphorus can easily cause eutrophication of water bodies, leading to environmental pollution. Traditional phosphorus-free scale inhibitors suffer from poor resistance to high hardness and weak chelating ability, resulting in a significant decrease in scale inhibition rate in high-calcium and magnesium water, failing to meet the requirements of harsh operating conditions. Furthermore, some scale inhibitors have complex preparation processes, requiring high-temperature polymerization reactions, resulting in high energy consumption and production costs, which is not conducive to large-scale promotion. For example, Chinese patent application CN103319010A discloses a scale and corrosion inhibitor containing organophosphonates and inorganic scale and corrosion inhibitor components; however, phosphorus can easily cause eutrophication of water bodies, leading to environmental pollution.

[0004] Therefore, developing a phosphorus-free, environmentally friendly, high-calcium-magnesium-hardness-resistant, highly efficient scale inhibitor with a simple preparation process is an urgent technical problem to be solved in this field. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a high-calcium-magnesium water quality scale inhibitor and its preparation method, which has good scale inhibition and environmental protection effects.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a scale inhibitor for high-calcium and magnesium water quality, comprising the following components by weight: 10-20 parts of polyepoxysuccinic acid, 3-8 parts of organic amine chelating agent, 4-6 parts of amino acid-modified polyaspartic acid, 3-5 parts of succinic acid ester, 1-3 parts of nonionic surfactant, 0.5-2 parts of pH adjuster, and 40-60 parts of deionized water.

[0007] Furthermore, the organic amine chelating agent is either sodium diethylenetriaminepentaacetate or triethylenetetraminehexaacetate.

[0008] Furthermore, the nonionic surfactant is any one of fatty alcohol polyoxyethylene ether and decyl glucoside.

[0009] Furthermore, the pH adjuster is either a 30% sodium hydroxide solution or a 30% potassium hydroxide solution.

[0010] Further, the preparation method of the succinic acid ester is as follows: succinic acid, pentaerythritol and p-toluenesulfonic acid are added to a reaction flask, and cyclohexane is added as a dehydrating agent. The reaction is carried out at 165-170℃ for 2-4 hours. After the reaction is completed, the mixture is distilled under reduced pressure and washed with ethanol to obtain the succinic acid ester.

[0011] Furthermore, the ratio of succinic acid, pentaerythritol, p-toluenesulfonic acid, and cyclohexane is 0.12-0.15 mmol: 0.25-0.3 mmol: 0.02-0.03 g: 5-8 mL.

[0012] Furthermore, it includes the following steps: S1. Polyepoxysuccinic acid, organic amine chelating agent, amino acid modified polyaspartic acid, succinic acid ester, nonionic surfactant, and deionized water are added to a stirrer and stirred for 10-15 minutes to obtain a mixed base liquid. S2. Add a pH adjuster to the mixed base liquid to adjust the pH value of the system to 7.0~8.5, stir at a constant temperature, and obtain a high calcium magnesium water quality scale inhibitor.

[0013] Furthermore, in step S2, the constant temperature stirring time is 10~12 minutes.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: This invention combines polyepoxysuccinic acid with an organic amine chelating agent, whose molecules are rich in high-density carboxyl and amino active coordination groups, enabling it to react with Ca in water. 2+ Mg 2+ Directional chelation and complexation occur, forming stable water-soluble chelates that block the nucleation basis of calcium and magnesium salt scale, making it suitable for high-hardness water conditions. Amino acid-modified polyaspartic acid, with its comb-like polymer structure, can embed into scale crystal growth sites, disrupting the regular lattice arrangement of calcium carbonate and magnesium carbonate scale, causing scale crystals to become distorted and deformed, generating loose, non-adhesive amorphous microcrystals. This prevents the formation of a dense, hard scale layer on pipe and equipment surfaces, reducing the risk of scale adhesion and deposition.

[0015] Succinic acid esters possess both hydrophilic and hydrophobic ester groups, working synergistically with nonionic surfactants to enhance the solubility and dispersibility of the agent in high-salinity, oil-water coexisting oilfield water. This effectively disperses suspended microcrystalline particles, preventing scale aggregation and sedimentation. Simultaneously, it optimizes system compatibility, avoiding stratification and turbidity, and improving the long-term storage stability of the product. Amino acid-modified polyaspartic acid and succinic acid esters can form a dense adsorption protective film on the metal substrate surface, isolating corrosive ions in the water from contact with the metal surface. While achieving highly efficient scale inhibition, this also imparts excellent corrosion inhibition properties to the agent, preventing corrosion perforation caused by scale buildup and extending the service life of oilfield water treatment equipment. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Polyepoxysuccinic acid, with an effective content of 90%.

[0018] The preparation of amino acid-modified polyaspartic acid was carried out according to the paper "Synthesis and Performance Study of Environmentally Friendly Scale Inhibitors and Corrosion Inhibitors Containing Amino Acids". A certain amount of PSI (polysuccinimide) and deionized water were placed in a three-necked flask and magnetically stirred to form a suspension. Certain amounts of glycine and tryptophan were dissolved separately in a 15% NaOH solution. When the temperature reached 40℃, the resulting glycine and tryptophan solutions were slowly added dropwise to the PSI suspension, reacting for 3 hours. After naturally cooling to room temperature, the pH of the solution was adjusted to neutral with dilute HCl. Then, a large amount of ethanol solution was poured in, precipitating the product, which was then washed repeatedly with ethanol. Finally, the product was vacuum dried at 60℃ for 12 hours to obtain a reddish-brown solid amino acid-modified polyaspartic acid.

[0019] Example 1 10 parts polyepoxysuccinic acid, 3 parts sodium diethylenetriaminepentaacetate, 4 parts amino acid-modified polyaspartic acid, 3 parts succinic acid ester, 1 part fatty alcohol polyoxyethylene ether, 0.5 parts 30% sodium hydroxide solution, and 60 parts deionized water. The preparation method of the succinic acid ester is as follows: succinic acid, pentaerythritol and p-toluenesulfonic acid are added to a reaction flask, and cyclohexane is added as a dehydrating agent. The reaction is carried out at 165°C for 2 hours. After the reaction is completed, the mixture is distilled under reduced pressure and washed with ethanol to obtain the succinic acid ester.

[0020] The ratio of succinic acid, pentaerythritol, p-toluenesulfonic acid, and cyclohexane used is 0.12 mmol: 0.25 mmol: 0.02 g: 5 mL.

[0021] The preparation method of a scale inhibitor for high-calcium and magnesium water quality includes the following steps: S1. Polyepoxysuccinic acid, organic amine chelating agent, amino acid modified polyaspartic acid, succinic acid ester, nonionic surfactant, and deionized water are added to a stirrer and stirred for 10 minutes to obtain a mixed base liquid. S2. Add a pH adjuster to the mixed base liquid to adjust the pH value of the system to 7.0, stir at a constant temperature for 10 minutes to obtain a high calcium and magnesium water quality scale inhibitor.

[0022] Example 2 A high-calcium-magnesium water quality scale inhibitor is composed of the following raw materials in parts by weight: 15 parts polyepoxysuccinic acid, 5 parts triethylenetetraminehexaacetic acid, 5 parts amino acid-modified polyaspartic acid, 4 parts succinic acid ester, 2 parts decyl glucoside, 1 part 30% potassium hydroxide solution, and 50 parts deionized water. The preparation method of the succinic acid ester is as follows: succinic acid, pentaerythritol and p-toluenesulfonic acid are added to a reaction flask, and cyclohexane is added as a dehydrating agent. The reaction is carried out at 168°C for 3 hours. After the reaction is completed, the mixture is distilled under reduced pressure and washed with ethanol to obtain the succinic acid ester.

[0023] The ratio of succinic acid, pentaerythritol, p-toluenesulfonic acid, and cyclohexane used is 0.13 mmol: 0.28 mmol: 0.025 g: 6 mL.

[0024] The preparation method of a scale inhibitor for high-calcium and magnesium water quality includes the following steps: S1. Polyepoxysuccinic acid, organic amine chelating agent, amino acid modified polyaspartic acid, succinic acid ester, nonionic surfactant, and deionized water are added to a stirrer and stirred for 12 minutes to obtain a mixed base liquid. S2. Add pH adjuster to the mixed base liquid to adjust the pH value of the system to 8, stir at constant temperature for 11 minutes to obtain a high calcium and magnesium water quality scale inhibitor.

[0025] Example 3 A high-calcium-magnesium scale inhibitor for water quality is composed of the following raw materials in parts by weight: 20 parts of polyepoxysuccinic acid, 8 parts of sodium diethylenetriaminepentaacetate, 6 parts of amino acid-modified polyaspartic acid, 5 parts of succinic acid ester, 3 parts of decyl glucoside, 2 parts of 30% sodium hydroxide solution, and 40 parts of deionized water. The preparation method of the succinic acid ester is as follows: succinic acid, pentaerythritol and p-toluenesulfonic acid are added to a reaction flask, and cyclohexane is added as a dehydrating agent. The reaction is carried out at 170°C for 4 hours. After the reaction is completed, the mixture is distilled under reduced pressure and washed with ethanol to obtain the succinic acid ester.

[0026] The ratio of succinic acid, pentaerythritol, p-toluenesulfonic acid, and cyclohexane used is 0.15 mmol: 0.3 mmol: 0.03 g: 8 mL.

[0027] The preparation method of a scale inhibitor for high-calcium and magnesium water quality includes the following steps: S1. Polyepoxysuccinic acid, organic amine chelating agent, amino acid modified polyaspartic acid, succinic acid ester, nonionic surfactant, and deionized water are added to a stirrer and stirred for 15 minutes to obtain a mixed base liquid. S2. Add a pH adjuster to the mixed base liquid to adjust the pH value of the system to 8.5, stir at a constant temperature for 12 minutes to obtain a high calcium and magnesium water quality scale inhibitor.

[0028] Comparative Example 1 The difference between this comparative example and Example 3 is that glycine is used instead of amino acid-modified polyaspartic acid.

[0029] Comparative Example 2 The difference between this comparative example and Example 3 is that succinic acid is used instead of succinic acid alcohol ester.

[0030] Performance Tests and Results According to GB / T16632-2019 Calcium Carbonate Deposition Method and SY / T5673-2020 Oilfield Water Treatment Agent Evaluation Method, the agent dosage was 20 mg / L, and the temperature was kept constant at 80℃ for 10 h. The scale inhibition rate and carbon steel corrosion inhibition rate were tested, and the results are shown in Table 1:

[0031] As shown in Table 1, Comparative Example 1 uses glycine to replace amino acid-modified polyaspartic acid. Glycine is only a small-molecule monoaminocarboxylic acid with low chelating capacity and short molecular chains, lacking steric hindrance and lattice distortion capabilities. In contrast, the amino acid-modified polyaspartic acid used in this invention has a high-molecular-weight comb-like structure with numerous carboxyl, amide, and amino active sites on its molecular chains. This allows for the simultaneous achievement of calcium and magnesium ion chelation, scale crystal lattice distortion, and electrostatic dispersion of scale particles. Furthermore, its long-chain structure can form a dense adsorption film on the metal surface, enhancing corrosion inhibition. With the replacement of glycine with small-molecule glycine, the system loses its high-molecular-weight dispersion and film-forming capabilities, resulting in insufficient chelation capacity, rapid scale growth and deposition, and an incomplete adsorption film on the metal surface. Consequently, both scale inhibition and corrosion inhibition performance are significantly reduced, and the solution stability deteriorates, becoming prone to turbidity.

[0032] Comparative Example 2 used succinic acid instead of succinic acid alcohol ester. Succinic acid is a small-molecule dicarboxylic acid with strong water solubility but weak lipophilicity. In oilfield reinjection water where oil and water coexist, its interfacial activity is poor, and it cannot effectively penetrate to the scale interface and metal surface. The succinic acid alcohol ester introduced in this invention is an esterification-modified product with both hydrophilic carboxyl groups and hydrophobic ester groups. It has good surface activity and wetting and dispersibility, which can enhance the solubility and dispersibility of the agent in high-mineralization, high-calcium-magnesium water, inhibit scale particle aggregation and adhesion, and synergistically improve the chelation efficiency of organic amine chelating agents. At the same time, the ester groups can enhance metal surface adsorption and improve corrosion inhibition performance. Directly using succinic acid as a substitute results in insufficient interfacial activity, decreased agent dispersibility, easy aggregation and sedimentation of calcium and magnesium scale, and weakened adsorption on the metal surface. Therefore, the scale inhibition rate and corrosion inhibition rate are significantly reduced, and stability problems such as system stratification and flocculent formation occur.

[0033] It should be noted that, in this document, 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 a process, method, article, or apparatus. Without further limitation, 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 said element.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-calcium-magnesium scale inhibitor for water quality, characterized in that, It includes the following components by weight: 10-20 parts of polyepoxysuccinic acid, 3-8 parts of organic amine chelating agent, 4-6 parts of amino acid-modified polyaspartic acid, 3-5 parts of succinic acid ester, 1-3 parts of nonionic surfactant, 0.5-2 parts of pH adjuster, and 40-60 parts of deionized water.

2. The scale inhibitor for high-calcium and magnesium water quality according to claim 1, characterized in that, The organic amine chelating agent is either sodium diethylenetriaminepentaacetate or triethylenetetraminehexaacetate.

3. The scale inhibitor for high-calcium and magnesium water quality according to claim 1, characterized in that, The nonionic surfactant is any one of fatty alcohol polyoxyethylene ether and decyl glucoside.

4. The scale inhibitor for high-calcium and magnesium water quality according to claim 1, characterized in that, The pH adjuster is either a 30% sodium hydroxide solution or a 30% potassium hydroxide solution.

5. The scale inhibitor for high-calcium and magnesium water quality according to claim 1, characterized in that, The preparation method of the succinic acid ester is as follows: succinic acid, pentaerythritol and p-toluenesulfonic acid are added to a reaction flask, and cyclohexane is added as a dehydrating agent. The reaction is carried out at 165-170℃ for 2-4 hours. After the reaction is completed, the mixture is distilled under reduced pressure and washed with ethanol to obtain the succinic acid ester.

6. The scale inhibitor for high-calcium and magnesium water quality according to claim 5, characterized in that, The ratio of succinic acid, pentaerythritol, p-toluenesulfonic acid, and cyclohexane used is 0.12-0.15 mmol: 0.25-0.3 mmol: 0.02-0.03 g: 5-8 mL.

7. A method for preparing a high-calcium-magnesium scale inhibitor for water quality as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Polyepoxysuccinic acid, organic amine chelating agent, amino acid modified polyaspartic acid, succinic acid ester, nonionic surfactant, and deionized water are added to a stirrer and stirred for 10-15 minutes to obtain a mixed base liquid. S2. Add a pH adjuster to the mixed base liquid to adjust the pH value of the system to 7.0~8.5, stir at a constant temperature, and obtain a high calcium and magnesium water quality scale inhibitor.

8. The method for preparing the high-calcium-magnesium scale inhibitor for water quality according to claim 7, characterized in that, In step S2, the constant temperature stirring time is 10~12 minutes.

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