Compound scale inhibitor and preparation method and application thereof

Abstract

The application provides a compounded scale inhibitor, a preparation method and application thereof, and relates to the fields of water treatment and energy. The compounded scale inhibitor provided by the application is obtained by compounding ester fatty alcohol polyoxyethylene ether maleic acid monoester-methyl methacrylate sulfonic acid sodium salt-maleic acid ternary polymer and sodium gluconate; wherein the mass content ratio of the added sodium gluconate and the ternary polymer in the compounding system is (0.8-1.0):1. The compounded scale inhibitor provided by the application has good Ca 2+ compatibility, can adapt to working environments with different Ca 2+ concentrations, has high scale inhibition efficiency, can well solve the CaCO3 scaling problem in the exploitation process of the enhanced geothermal system, guarantees the safe and stable operation of the system, and ensures the sustainable exploitation of heat energy.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water treatment and energy, in particular to a compound scale inhibitor and a preparation method and application thereof. BACKGROUND

[0002] With the continuous high-speed development of the world economy, problems such as energy shortage, environmental pollution and ecological deterioration are becoming increasingly prominent. As a new type of clean and renewable geothermal energy, hot dry rock has attracted widespread attention from countries around the world. The utilization process of hot dry rock heat energy mainly includes: through hydraulic stimulation, fractures are created in low-permeability hot dry rock reservoirs, and the hot dry rock reservoir is transformed into an enhanced geothermal system (EGS). Then, low-temperature circulating water is injected into the hot dry rock reservoir along the fractures, and after the heat exchange between the circulating water and the hot dry rock is completed, high-temperature circulating water is obtained, which is then extracted from the production well for power generation and comprehensive utilization. However, in the practice of EGS, the exploitation mode of the enhanced geothermal system using circulating water as the heat energy carrier can lead to the dissolution of inorganic salt ions and the formation of calcium carbonate scale on the surface of the reservoir fractures, water outlet well and heat exchanger, which seriously affects the sustainable utilization of the hot dry rock reservoir and the heat energy exploitation equipment.

[0003] Adding a scale inhibitor is the main way to prevent CaCO3 precipitation in geothermal production. Currently, the scale inhibitors commonly used in geothermal production mainly include organic phosphonate, polyphosphate and polycarboxylate. Among them, organic phosphonate can be hydrolyzed to orthophosphate at high temperatures, losing the scale inhibition performance. Polyphosphate scale inhibitors have been widely used in solving the problem of geothermal circulating water scaling. However, the phosphorus element in the process of use can lead to eutrophication of water bodies, which does not meet the current green and environmental protection requirements. The weak acidity of the carboxyl group in the polycarboxylate scale inhibitor can promote the formation of gel of the polycarboxylate scale inhibitor at high Ca 2+ concentrations, reducing the scale inhibition efficiency. Therefore, it is urgent to develop a high-efficiency scale inhibitor suitable for EGS with compatibility for high temperature and high Ca 2+ concentration. SUMMARY

[0004] The present application provides a compound scale inhibitor and a preparation method and application thereof. The compound scale inhibitor has good Ca 2+ compatibility, can adapt to different Ca 2+ concentration working environments, has high scale inhibition efficiency, can well solve the CaCO3 scaling problem in the exploitation process of the enhanced geothermal system, and ensures the safe and stable operation of the system.

[0005] In order to achieve the above purpose, the present application provides a compound scale inhibitor, which is obtained by compounding ester aliphatic alcohol polyoxyethylene ether maleic acid monoester-sodium methallyl sulfonate-maleic acid terpolymer and sodium gluconate.

[0006] The mass ratio of sodium gluconate to ternary polymer in the compound system is (0.8-1.0):1.

[0007] In the above scheme, the purpose of compounding the ternary polymer with sodium gluconate is to improve the scale inhibitor's ability to react with Ca. 2+ The capture efficiency is improved, and the scale inhibitor and Ca are enhanced. 2+ The dispersibility of the complex. Specifically, when the sodium gluconate:terpolymer ratio in the compound scale inhibitor is 0, a large amount of Ca... 2+ The head containing the carboxyl group is concentrated, and the ternary polymer and Ca 2+ The resulting chelate molecules have a large configuration, leading to the reaction between the scale inhibitor and Ca. 2+ Co-precipitation leads to a decrease in scale inhibition efficiency. When the ratio of sodium gluconate to ternary polymer in the compound scale inhibitor is low (0.2–0.4), the carboxyl groups in sodium gluconate will replace some of the carboxyl groups in the ternary polymer and react with Ca. 2+ Chelation gradually reduces the chelation of carboxyl groups in the ternary polymer. 2+ The pressure, and through steric hindrance, causes the side chains of the ternary polymer molecules to gradually unfold from a spiral shape, increasing the number of active sites exposed in the water. Simultaneously, the formed ternary polymer -Ca... 2+ - Sodium gluconate chelates compared to ternary polymers - Ca 2+ The chelate molecule has a smaller conformation and better dispersibility. When the ratio of sodium gluconate to ternary polymer in the compound scale inhibitor is further increased (0.4–0.8), the degree of substitution of the carboxyl groups in the ternary polymer by the carboxyl groups in sodium gluconate further increases, the side chains of the ternary polymer molecule further expand, and the number of active sites exposed in the water further increases. The resulting scale inhibitor reacts with Ca... 2+ The chelate dispersion performance is further enhanced. When the ratio of sodium gluconate to ternary polymer in the compound scale inhibitor is high (0.8–1.0), the side chains of the ternary polymer molecules are fully extended, and the active sites are fully exposed in the water. Simultaneously, the scale inhibitor reacts with Ca... 2+ The chelate is sodium gluconate-Ca 2+ ternary polymer-Ca 2+ and sodium gluconate-Ca 2+ - The ternary polymer exists in three forms, thereby enhancing the effect of the compounded scale inhibitor on Ca in solution under different conditions. 2+ Its dispersion ability.

[0008] Table 1 shows the scale inhibition rates of the compound scale inhibitors with different sodium gluconate:terpolymer ratios, as follows:

[0009]

[0010]

[0011] As a preference, the molecular weight of the terpolymer is 2000-3000. It can be understood that the molecular weight of the terpolymer in the complex scale inhibitor obtained by the present application should be controlled within the above range, and the purpose is to maintain high scale inhibition efficiency. If the molecular weight is above 4000, the diffusion and dispersion performance of the polymer molecules is reduced, and the polymer and scale inhibitor chelate precipitate is easily generated.

[0012] As a preference, the ester fatty alcohol polyoxyethylene ether maleate monoester-sodium methallyl sulfonate-maleic acid terpolymer is prepared by the following steps:

[0013] The reaction container with stirring function is placed in a water bath to heat the system to 40-60°C, and then deionized water, maleic anhydride and sodium bisulfite are added and stirred and dissolved;

[0014] Then the system is heated to 70-90°C, and an aqueous solution of ammonium sulfite, sodium methallyl sulfonate and ester fatty alcohol polyoxyethylene ether maleate monoester is added dropwise into the reaction container, and the dropwise addition is completed within 25-40 min;

[0015] After the dropwise addition is completed, the temperature of the system is increased to 85-100°C, and the stirring is continued, and after 2-5 h of reaction, the pH value of the solution is adjusted to 6.5-8, methanol is added to precipitate the product, and after washing and drying, the ester fatty alcohol polyoxyethylene ether maleate monoester-sodium methallyl sulfonate-maleic acid terpolymer is obtained.

[0016] As a preference, when the terpolymer is synthesized, the mass content of the deionized water added is 49-59%; the mass content of the ester fatty alcohol polyoxyethylene ether maleate monoester added is 7-14%; the mass content of the sodium methallyl sulfonate added is 8-17%; and the mass content of the maleic acid added is 25-31%.

[0017] It can be understood that in the above scheme, the mass content of each component added should be strictly controlled, because the content has an important influence on the completeness of the polymerization reaction. Specifically, if the mass content of the ester fatty alcohol polyoxyethylene ether maleate monoester added is less than 7%, the molecular weight of the synthesized polymer is too low, and if it is higher than 14%, the molecular weight of the synthesized polymer is too high; if the mass content of the sodium methallyl sulfonate added is less than 8%, the molecular weight of the synthesized polymer is too low, and if it is higher than 17%, the molecular weight of the synthesized polymer is too high; and if the mass content of the maleic acid added is less than 25%, the molecular weight of the synthesized polymer is too low, and if it is higher than 31%, the molecular weight of the synthesized polymer is too high.

[0018] As preferred, when the ternary polymer is synthesized, both sodium bisulfite and ammonium sulfite are added as initiators, wherein the mass content of the added sodium bisulfite is 1% to 2%, the mass content of the added ammonium sulfite is 1% to 2%, and the sum of the two is 3% to 4% of the total mass of the reaction system.

[0019] It can be understood that in the above scheme, the added initiator has an important influence on the start of the polymerization reaction. Specifically, if the amount of the added initiator is less than 3% of the total mass, the polymerization reaction is incomplete and the polymerization degree of the polymer is low; if the amount of the added initiator is more than 4% of the total mass, the polymerization degree of the polymer is too high and is prone to cause violent polymerization.

[0020] As preferred, the ester fatty alcohol polyoxyethylene ether maleic acid monoester is prepared by the following steps:

[0021] The ester fatty alcohol polyoxyethylene ether and maleic anhydride are added to a reaction container provided with a stirrer and a thermometer, and an esterification reaction is carried out at 70°C to 85°C in a water bath for 1h to 3h. The reaction is stopped, and then 2.4% NaOH solution is quickly added to obtain a yellow translucent ester fatty alcohol polyoxyethylene ether maleic acid monoester.

[0022] It can be understood that in the above scheme, the inventors optimize the preparation method of the ester fatty alcohol polyoxyethylene ether monomer, which can effectively increase the reaction rate and degree of esterification reaction, increase the polymerization degree of the epoxy monomer in the polymerization reaction, increase the diffusion of the scale inhibitor molecules in the aqueous solution, and improve the scale inhibition efficiency. In addition, the double bond and carboxyl group can be introduced into the ester fatty alcohol polyoxyethylene ether through the esterification reaction, which aims to enable the ester fatty alcohol polyoxyethylene ether to participate in the polymerization reaction. At the same time, the ester fatty alcohol polyoxyethylene ether maleic acid monoester does not pollute the water body and can be biodegraded.

[0023] As preferred, the mass content ratio of the added ester fatty alcohol polyoxyethylene ether and maleic anhydride in the polymerization reaction system is (4.55 to 8.13):1.

[0024] The volume ratio of the added ester fatty alcohol polyoxyethylene ether and maleic anhydride is (2.66 to 3.22):1.

[0025] As preferred, the mass ratio of the 2.4% NaOH solution to the maleic anhydride is (1.41 to 1.56):1.

[0026] The application also provides a complex scale inhibitor according to any one of the above technical solutions in [CO3 2- ]>2300mg / L -1 , [Ca 2+ ]>2300mg / L -1Application in the circulating water of enhanced geothermal systems with a water temperature of 100℃~120℃.

[0027] Preferably, the dosage of the compound scale inhibitor is 12 mg / L. -1～ 20mg L -1 .

[0028] Preferably, the compound scale inhibitor is added at a dosage of 12 mg / L. -1 The scale inhibition efficiency reaches over 98.7% at a dosage of 20 mg / L. -1 The accuracy rate reached over 99.4%.

[0029] This invention also provides a method for treating circulating water in an enhanced geothermal system, the method comprising adding a scale inhibitor to the circulating water of the enhanced geothermal system according to any of the above technical solutions, wherein the enhanced geothermal system circulating water contains [CO3] 2- 2300mg / L -1 [Ca] 2+ 2300mg / L -1 Its temperature is 100℃~120℃.

[0030] Preferably, the dosage of the compound scale inhibitor is 12 mg / L. -1 ~20mg L -1 .

[0031] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0032] 1. The compound scale inhibitor provided by this invention has epoxy groups and carboxylic acid groups, and has high solubility and strong Ca2+ properties. 2+ Chelating force can rapidly chelate large amounts of Ca. 2+ Reduce free Ca in the system 2+ Concentration, reducing Ca 2+ The self-diffusion coefficient is high, thereby reducing the amount of CaCO3 precipitation caused by increased temperature and enhanced molecular thermal motion. Furthermore, the compound scale inhibitor of this invention also contains sulfonic acid groups, exhibiting strong dispersibility and can be used in high-Ca... 2+ At certain concentrations, the scale inhibitor and Ca formed 2+ The chelate exists stably in solution and can withstand high temperatures and high Ca2+. 2+ The concentration environment meets the needs of on-site production.

[0033] 2. The compound scale inhibitor provided by this invention is nitrogen-free, phosphorus-free, and non-toxic, making it environmentally friendly and not affecting subsequent work after application. Furthermore, this scale inhibitor has high economic value and broad application prospects.

[0034] 3. The compound scale inhibitor of the present invention can adapt to different [Ca]2+ The working environment of the application has high scale inhibition performance, and can well solve the CaCO3 scale problem in the process of enhanced geothermal system heat energy exploitation, and ensure the sustainable exploitation of heat energy. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0036] Embodiment 1

[0037] The ingredient preparation amount (mass parts) is as follows, calculated on the basis of producing 1000 mass parts of the fatty alcohol polyoxyethylene ether maleic acid monomer:

[0038] The reactor with stirring function is placed in a water bath to raise the system temperature to 50 DEG C, then 667 mass parts of the fatty alcohol polyoxyethylene ether and 145 mass parts of maleic anhydride are poured into the reaction container, and stirred and dissolved.

[0039] After dissolution, the system temperature is raised to 70 DEG C, and stirring is continued. After 1 h of reaction, 188 mass parts of 2.4% NaOH aqueous solution is quickly added, and a yellow translucent fatty alcohol polyoxyethylene ether maleic acid monomer is obtained.

[0040] Embodiment 2

[0041] The ingredient preparation amount (mass parts) is as follows, calculated on the basis of producing 1000 mass parts of the fatty alcohol polyoxyethylene ether maleic acid monomer:

[0042] The reactor with stirring function is placed in a water bath to raise the system temperature to 50 DEG C, then 714 mass parts of the fatty alcohol polyoxyethylene ether and 115 mass parts of maleic anhydride are poured into the reaction container, and stirred and dissolved.

[0043] After dissolution, the system temperature is raised to 78 DEG C, and stirring is continued. After 2 h of reaction, 171 mass parts of 2.4% NaOH aqueous solution is quickly added, and a yellow translucent fatty alcohol polyoxyethylene ether maleic acid monomer is obtained.

[0044] Embodiment 3

[0045] The ingredient preparation amount (mass parts) is as follows, calculated on the basis of producing 1000 mass parts of the fatty alcohol polyoxyethylene ether maleic acid monomer:

[0046] The reactor with stirring function was placed in a water bath to raise the system temperature to 50°C, then 761 parts by mass of fatty alcohol polyoxyethylene ether and 94 parts by mass of maleic anhydride were poured into the reaction vessel and stirred and dissolved.

[0047] After dissolution, the system temperature was raised to 85°C, stirring was continued, and after 3 hours of reaction, 145 parts by mass of 2.4% NaOH aqueous solution was quickly added, to obtain a yellow translucent fatty alcohol polyoxyethylene ether maleic acid monoester.

[0048] The fatty alcohol polyoxyethylene ether maleic acid monoester synthesized in Example 1 of the above Examples 1-3 was used to synthesize the terpolymers in the following examples and comparative examples.

[0049] Example 4

[0050] The amounts of each ingredient (parts by mass) were as follows, calculated on the basis of production of 1000 parts by mass of terpolymer:

[0051] The reaction vessel with stirring function was placed in a water bath to raise the system temperature to 50°C, then 550 parts by mass of deionized water, 253 parts by mass of maleic anhydride, and 13 parts by mass of sodium bisulfite were poured into the reaction vessel and stirred and dissolved;

[0052] After the system was raised to 80°C, 18 parts by mass of ammonium sulfite, 82 parts by mass of sodium methallyl sulfonate, and 84 parts by mass of ester fatty alcohol polyoxyethylene ether maleic acid monoester were added dropwise at the same time, and the dropwise addition was completed within 30 minutes;

[0053] After the dropwise addition was completed, the system temperature was raised to 90°C, stirring was continued, and after 3 hours of reaction, the solution pH was adjusted to 7, methanol was added to precipitate the product, and the product was repeatedly washed with 99.5% ethanol, and the washed product was dried at 50°C, to obtain a terpolymer with a molecular weight of 2840;

[0054] Example 5

[0055] The amounts of each ingredient (parts by mass) were as follows, calculated on the basis of production of 1000 parts by mass of terpolymer:

[0056] The reaction vessel with stirring function was placed in a water bath to raise the system temperature to 50°C, then 495 parts by mass of deionized water, 267 parts by mass of maleic anhydride, and 14 parts by mass of sodium bisulfite were poured into the reaction vessel and stirred and dissolved;

[0057] After the system was raised to 80°C, 19 parts by mass of ammonium sulfite, 94 parts by mass of sodium methallyl sulfonate, and 135 parts by mass of ester fatty alcohol polyoxyethylene ether maleic acid monoester were added dropwise at the same time, and the dropwise addition was completed within 30 minutes;

[0058] After the addition was complete, the system temperature was raised to 90℃ and stirred continuously. After reacting for 3 hours, the pH of the solution was adjusted to 7, methanol was added to precipitate the product, and the product was washed repeatedly with 99.5% ethanol. The washed product was dried at 50℃ to obtain the ternary polymer with a molecular weight of 2940.

[0059] Example 6

[0060] Based on the production of 1000 parts by weight of ternary polymer, the preparation quantities (parts by weight) of each component are as follows:

[0061] Place the reaction vessel with stirring function in a water bath to raise the system temperature to 50°C, then pour 511 parts by mass of deionized water, 264 parts by mass of maleic anhydride and 15 parts by mass of sodium bisulfite into the reaction vessel and stir to dissolve.

[0062] After heating the system to 80°C, 18 parts by mass of ammonium sulfite, 81 parts by mass of sodium methacrylate sulfonate and 111 parts by mass of fatty alcohol polyoxyethylene ether maleic acid monoester were added dropwise simultaneously and the addition was completed within 30 minutes.

[0063] After the addition was complete, the system temperature was raised to 90°C and stirred continuously. After 3 hours of reaction, the pH of the solution was adjusted to 7, methanol was added to precipitate the product, and the product was washed repeatedly with 99.5% ethanol. The washed product was dried at 50°C to obtain the ternary polymer with a molecular weight of 2917.

[0064] Example 7

[0065] Based on the production of 1000 parts by weight of the compound scale inhibitor, the preparation quantities (parts by weight) of each component are as follows:

[0066] 444 parts by weight of sodium gluconate and 556 parts by weight of the ternary polymer (0.80:1) were placed in a reaction vessel equipped with a stirring function and stirred until homogeneous to obtain the high-Ca content. 2+ Compatible scale inhibitor.

[0067] Example 8

[0068] Based on the production of 1000 parts by weight of the compound scale inhibitor, the preparation quantities (parts by weight) of each component are as follows:

[0069] 476 parts by weight of sodium gluconate and 524 parts by weight of the ternary polymer (0.91:1) were placed in a reaction vessel equipped with a stirring function and stirred until homogeneous to obtain the high-Ca content. 2+ Compatible scale inhibitor.

[0070] Example 9

[0071] Based on the production of 1000 parts by weight of the compound scale inhibitor, the preparation quantities (parts by weight) of each component are as follows:

[0072] Put 496 parts by mass of sodium gluconate and 504 parts by mass of the ternary polymer (0.98: 1) in a reaction vessel with stirring function to stir and dissolve uniformly, to obtain the high-Ca 2+ Compatible scale inhibitor.

[0073] Example 10

[0074] The amount of each ingredient (mass parts) is as follows, calculated on the basis of 1000 mass parts of the compounded scale inhibitor:

[0075] Put 500 parts by mass of sodium gluconate and 500 parts by mass of the ternary polymer (1.0: 1) in a reaction vessel with stirring function to stir and dissolve uniformly, to obtain the high-Ca 2+ Compatible scale inhibitor.

[0076] Comparative Example 1

[0077] The preparation method of the fatty alcohol polyoxyethylene ether maleic acid monomer is the same as that of Example 1, and the preparation method of the ternary polymer is the same as that of Example 4, except that the sodium bisulfite is added to 34 parts in the formula, the ammonium sulfite is adjusted to 27 parts, and the deionized water is adjusted to 520 parts. The molecular weight of the obtained ternary polymer is 5010. The high-Ca 2+ The preparation method of the compatible scale inhibitor is the same as that of Example 7.

[0078] Comparative Example 2

[0079] The preparation method of the fatty alcohol polyoxyethylene ether maleic acid monomer is the same as that of Example 2, and the preparation method of the ternary polymer is the same as that of Example 4, except that the temperature after the completion of the dropwise addition is adjusted to 70°C. The molecular weight of the obtained ternary polymer is 1325. The high-Ca 2+ The preparation method of the compatible scale inhibitor is the same as that of Example 7.

[0080] Comparative Example 3

[0081] The preparation method of the fatty alcohol polyoxyethylene ether maleic acid monomer is the same as that of Example 3, and the preparation method of the ternary polymer is the same as that of Example 5, except that no fatty alcohol polyoxyethylene ether maleic acid monomer is added in the formula, and the deionized water is adjusted to 630 parts. The molecular weight of the obtained ternary polymer is 1692. The high-Ca 2+ The preparation method of the compatible scale inhibitor is the same as that of Example 8.

[0082] Comparative Example 4

[0083] The preparation method of the fatty alcohol polyoxyethylene ether maleic acid monomer is the same as that of Example 1, and the preparation method of the ternary polymer is the same as that of Example 4. The high-Ca 2+The preparation method of the compatible scale inhibitor is the same as that of Example 8, except that the sodium gluconate in the formula is adjusted to 300 parts, and the terpolymer is adjusted to 700 parts. The molecular weight of the obtained terpolymer is 2871. High Ca 2+ The preparation method of the compatible scale inhibitor is the same as that of Example 9.

[0084] Comparative Example 5

[0085] The preparation method of the fatty alcohol polyoxyethylene ether maleic acid monomer is the same as that of Example 2, and the preparation method of the terpolymer is the same as that of Example 5. High Ca 2+ The preparation method of the compatible scale inhibitor is the same as that of Example 9, except that the sodium gluconate in the formula is adjusted to 700 parts, and the terpolymer is adjusted to 300 parts. The molecular weight of the obtained terpolymer is 2947. High Ca 2+ The preparation method of the compatible scale inhibitor is the same as that of Example 10.

[0086] Performance test

[0087] The scale inhibition tests of Examples 7-10, Comparative Examples 1-5, and commercially available products are carried out by using a static bottle scale inhibition method. The scale inhibition test is carried out at 2300mg / L -1 Ca 2+ , 2300mg / L -1 Test temperature: 120℃, test time: 10h, and the dosing concentrations of the agents are 12mg / L -1 , 18mg / L -1 , and 20mg / L -1 .

[0088] The specific test results are shown in Table 2 below:

[0089]

[0090]

[0091] As can be seen from Table 2 above, the scale inhibition effect of the compound scale inhibitor of the present application is excellent. When the dosing amount of the compound scale inhibitor is 12mg / L -1 , the scale inhibition efficiency is 98.7% or more, and when the dosing amount is 20mg / L -1 , the scale inhibition efficiency is 99.4% or more.

[0092] Comparing example 7 with comparative example 1, it can be found that the scale inhibition efficiency of example 7 is higher, which shows that the initiator has a great influence on the molecular weight of the terpolymer. Only the initiator with a proper amount can ensure the stability of the molecular weight of the polymer and improve the scale inhibition efficiency. Comparing example 7 with comparative example 2, it can be found that the scale inhibition efficiency of example 7 is higher, which shows that the decrease of the temperature weakens the degree of the polymerization reaction, resulting in the decrease of the molecular weight of the polymer. Therefore, the reaction temperature of the terpolymer should be controlled at 90-100℃. Comparing example 8 with comparative example 3, it can be found that the scale inhibition efficiency of example 8 is higher, which shows that the addition of the ester aliphatic alcohol polyoxyethylene ether maleic acid monoester is beneficial to the improvement of the scale inhibition efficiency of the polymer. Comparing example 9 with comparative example 4, it can be found that the scale inhibition efficiency of example 9 is higher, which shows that the low mass content of sodium gluconate in the compounded system is not conducive to the improvement of the scale inhibition efficiency of the compounded scale inhibitor. Comparing example 10 with comparative example 5, it can be found that the scale inhibition efficiency of example 10 is higher, which shows that the high mass content of sodium gluconate in the compounded system is not conducive to the improvement of the scale inhibition efficiency of the compounded scale inhibitor. Meanwhile, only when the mass content of sodium gluconate in the compounded system is within the range of the present application, the optimal effect can be achieved.

Claims

1. A compounded scale inhibitor, characterized in that, The ester aliphatic alcohol polyoxyethylene ether maleic acid monoester-sodium methacrylate sulfonate-maleic acid ternary polymer is compounded with sodium gluconate; The mass content ratio of the added sodium gluconate and the ternary polymer in the compound system is (0.8-1.0):1; The molecular weight of the ternary polymer is 2000-3000; The ester aliphatic alcohol polyoxyethylene ether maleic acid monoester is prepared by the following steps: The ester aliphatic alcohol polyoxyethylene ether and maleic anhydride are added into a reaction container provided with a stirrer and a thermometer, and esterification is carried out at 70-85 DEG C in a water bath for 1-3 hours, then 2.4% NaOH solution is quickly added to obtain yellow translucent ester aliphatic alcohol polyoxyethylene ether maleic acid monoester; The mass content ratio of the added ester aliphatic alcohol polyoxyethylene ether and maleic anhydride in the polymerization system is (4.55-8.13):1; The volume ratio of the added ester aliphatic alcohol polyoxyethylene ether and maleic anhydride is (2.66-3.22):1; The mass content ratio of the added 2.4% NaOH solution and maleic anhydride is 1:(1.41-1.56); The ester aliphatic alcohol polyoxyethylene ether maleic acid monoester-sodium methacrylate sulfonate-maleic acid ternary polymer is prepared by the following steps: The reaction container with stirring function is placed in a water bath to heat the system to 40-60 DEG C, then deionized water, maleic anhydride and sodium bisulfite are added and stirred to dissolve; Then the system is heated to 70-90 DEG C, and the aqueous solution of ammonium sulfite, sodium methacrylate sulfonate and ester aliphatic alcohol polyoxyethylene ether maleic acid monoester is added dropwise into the reaction container, and the dropping is completed within 25-40 minutes; After the dropping is completed, the temperature of the system is increased to 85-100 DEG C, and the stirring is continued, and after 2-5 hours of reaction, the pH value of the solution is adjusted to 6.5-8, methanol is added to precipitate the product, and after washing and drying, the ester aliphatic alcohol polyoxyethylene ether maleic acid monoester-sodium methacrylate sulfonate-maleic acid ternary polymer is obtained; When synthesizing the ternary polymer, the mass content of the added deionized water is 49-59%; the mass content of the added ester aliphatic alcohol polyoxyethylene ether maleic acid monoester is 7-14%; the mass content of the added sodium methacrylate sulfonate is 8-17%; and the mass content of the added maleic anhydride is 25-31%; When synthesizing the ternary polymer, the sodium bisulfite and ammonium sulfite are both initiators, wherein the mass content of the added sodium bisulfite is 1-2%, the mass content of the added ammonium sulfite is 1-2%, and the sum of the two is 3-4% of the total mass of the reaction system.

2. The compound scale inhibitor according to claim 1 in [CO3] 2- 2300 mg L -1 [Ca] 2+ 2300 mg L -1 Application in the circulating water of enhanced geothermal systems with a water temperature of 100℃~120℃.

3. Use according to claim 2, characterized in that, The complexing scale inhibitor is used in an amount of 12 mg / L -1 20 mg / L -1 .

4. Use according to claim 3, characterized in that, The complex antifouling agent has an antifouling efficiency of 98.7% or more when the dosage is 12 mg / L -1 and 99.4% or more when the dosage is 20 mg / L -1 The complex antifouling agent has an antifouling efficiency of 98.7% or more when the dosage is 12 mg / L -1 and 99.4% or more when the dosage is 20 mg / L -1 5. A method of treating enhanced geothermal system circulating water, characterized by, The method comprises adding the compound scale inhibitor of claim 1 into the enhanced geothermal system circulating water, wherein the concentration of [CO3 2- ]> 2300 mg / L -1 , [Ca 2+ ]> 2300 mg / L -1 , and the temperature is 100-120℃.

6. The processing method according to claim 5, characterized in that, The complexing scale inhibitor is used in an amount of 12 mg / L -1 20 mg / L -1 .

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