Composite corrosion and scale inhibitors, their preparation methods and applications, and methods for corrosion and scale inhibition in geothermal water.

Abstract

The present application relates to geothermal water composite corrosion and scale inhibitor, the scale inhibitor contains the following components: long chain alkyl-dimethyl-polyethylene glycol ammonium sulfite, organic phosphine compound, organic alkali, water-soluble inorganic zinc salt and water.The composite corrosion and scale inhibitor provided by the present application has good corrosion and scale inhibition effect in the low-temperature, oxygen-containing environment geothermal water system.

Description

Technical Field

[0001] This invention relates to the field of geothermal corrosion and scale inhibition, specifically to composite corrosion and scale inhibitors, their preparation methods and applications, and methods for geothermal corrosion and scale inhibition. Background Technology

[0002] With the rapid depletion of non-renewable resources such as oil and natural gas, geothermal energy, as a new energy source with broad development prospects, is receiving increasing attention.

[0003] Geothermal energy is an energy source that can be used for various forms of industrial and agricultural applications, such as heating, power generation, cooling, medical treatment, bathing, and aquaculture. Geothermal fluids include geothermal water, two-phase mixtures of geothermal water and steam, and geothermal steam, among others.

[0004] The chemical composition of geothermal fluids is very complex, containing corrosive components such as dissolved oxygen and chloride ions, and scaling components such as calcium ions and silicates. This leads to corrosion and scaling problems in geothermal equipment, pipes, and fittings, hindering the efficient and economical utilization of geothermal energy. Besides the properties of the geothermal fluids, corrosion and scaling are also affected by operating conditions such as temperature and pressure, as well as the materials used in the equipment.

[0005] Currently, the main methods for controlling corrosion during the utilization of geothermal water are as follows:

[0006] (1) Select corrosion-resistant materials: In addition to non-metallic materials (such as PVC-U plastic pipes), high alloy stainless steel, nickel-based alloys, titanium alloys and zirconium materials can also be selected to increase the reliability of the geothermal system; (2) Modify the coating on the metal substrate: Apply a corrosion-resistant coating to the surface of inexpensive metals to increase the corrosion resistance of the metals. Currently, such coatings mainly include polyphenylene sulfide-based coatings, metal ceramic coatings, micro-nano SiO2 coatings, etc.; (3) Add chemical corrosion inhibitors: According to the working conditions of geothermal water, the main corrosion inhibitors developed are sodium tripolyphosphate and hydrolyzed polymaleic anhydride, etc.; (4) Cathodic protection: Use the sacrificial anode method to carry out electrochemical corrosion protection for the equipment; (5) Pre-treatment such as washing before geothermal utilization: Use pre-treatment processes such as washing to remove corrosive gases and corrosive ions in the geothermal fluid.

[0007] Currently, the main methods for scale inhibition in geothermal water utilization are as follows:

[0008] (1) Add chemical scale inhibitors; (2) Pre-treat and descale before geothermal utilization or reinjection; (3) Apply physical field to descale; (4) Use scale inhibitor coatings; (5) Use system pressurization method to inhibit scale.

[0009] Due to the high price of corrosion-resistant materials, the fact that coating corrosion prevention has not yet been well resolved due to the difference in yield stress between the metal substrate (such as carbon steel) and the coating (especially organic coating), resulting in poor bonding between the coating and the substrate, the need to limit the application of chemical agents from an environmental protection perspective, and issues related to electrode material selection and process operation, the corrosion and scaling problem in geothermal water utilization has not been well resolved, making the corrosion and scaling problem in geothermal systems a bottleneck in the development and utilization of geothermal resources.

[0010] Currently, in the field of geothermal water corrosion and scale inhibition, there are no environmentally friendly corrosion and scale inhibitors specifically designed for medium- and low-temperature (30–140℃) oxygen-containing environments. The corrosion and scaling problems in medium- and low-temperature, oxygen-containing geothermal systems are mainly characterized by high mineralization, the presence of a certain concentration of dissolved oxygen and carbon dioxide, and the presence of microorganisms such as sulfate-reducing bacteria, resulting in strong corrosion and scaling, making them more difficult to control.

[0011] Therefore, in order to solve the above-mentioned existing technical problems, it is necessary to develop environmentally friendly corrosion and scale inhibitors for geothermal water systems in medium-low temperature and oxygen-containing environments. Summary of the Invention

[0012] The first aspect of this invention is to overcome the shortcomings of existing methods and provide a geothermal corrosion and scale inhibitor suitable for medium-low temperature, oxygen-containing environments.

[0013] A second aspect of the present invention provides a method for preparing a composite corrosion and scale inhibitor.

[0014] The third aspect of this invention provides the application of the composite corrosion and scale inhibitor described in the first aspect in geothermal water corrosion and scale inhibition.

[0015] The fourth aspect of this invention provides a method for inhibiting corrosion and scale in geothermal water.

[0016] The inventors of this invention unexpectedly discovered during their research that using long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite can significantly improve the corrosion inhibition effect of geothermal water corrosion and scale inhibition technology. In view of this, the inventors have provided the solution of this invention.

[0017] To achieve the above objectives, the first aspect of the present invention provides a composite corrosion and scale inhibitor composition, which contains the following components: long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite, organophosphorus compound, organic base, water-soluble inorganic zinc salt and water.

[0018] In a preferred embodiment, the composite corrosion and scale inhibitor composition of the present invention further contains one or two of a polycarboxylated polymer and a gluconate.

[0019] Relative to 100 parts by weight of the composite corrosion and scale inhibitor composition, the content of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite is 5-15 parts by weight, the content of the polycarboxyl polymer is 0-15 parts by weight, the content of the gluconate is 0-15 parts by weight, the content of the organophosphorus compound is 2-10 parts by weight, the content of the organic base is 12-25 parts by weight, the content of the water-soluble inorganic zinc salt is 4-15 parts by weight, and the balance is mainly water.

[0020] The long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite has the structure shown in the following formula.

[0021]

[0022] In the formula, n is 2-6 and x is 6-30.

[0023] A second aspect of the present invention provides a method for preparing a composite corrosion and scale inhibitor, the method comprising: mixing the components in the composite corrosion and scale inhibitor composition described in the first aspect.

[0024] Preferably, the mixing conditions at least satisfy the following: temperature of 10-30℃, time of 0.5-1h, and stirring speed of 60-90rpm.

[0025] The third aspect of this invention provides the application of the composite corrosion and scale inhibitor described in the first aspect in geothermal water corrosion and scale inhibition.

[0026] The fourth aspect of the present invention provides a method for inhibiting corrosion and scale in geothermal water, the method comprising: adding the composite corrosion and scale inhibitor described in the first aspect to the geothermal water before the geothermal water is discharged from the well.

[0027] Compared with existing geothermal water corrosion and scale inhibition technologies, the composite corrosion and scale inhibitor provided by this invention has a good corrosion and scale inhibition effect in geothermal water systems with medium and low temperature and oxygen-containing environments.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0029] The specific embodiments of this application are described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0030] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0031] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0032] As previously stated, a first aspect of the present invention provides a composite corrosion and scale inhibitor comprising the following components: long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite, an organophosphorus compound, an organic base, a water-soluble inorganic zinc salt, and water.

[0033] In a preferred embodiment, the composite corrosion and scale inhibitor of the present invention further contains one or two of a polycarboxylated polymer and a gluconate.

[0034] In a preferred embodiment, relative to 100 parts by weight of the composite corrosion and scale inhibitor, the content of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite is 5-15 parts by weight, the content of the polycarboxyl polymer is 0-15 parts by weight, the content of the gluconate is 0-15 parts by weight, the content of the organophosphorus compound is 2-10 parts by weight, the content of the organic base is 12-25 parts by weight, the content of the water-soluble inorganic zinc salt is 4-15 parts by weight, and the balance is mainly water.

[0035] Preferably, relative to 100 parts by weight of the composite corrosion and scale inhibitor, the content of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite is 8-12 parts by weight, the content of the polycarboxyl polymer is 2-12 parts by weight, the content of the gluconate is 2-12 parts by weight, the content of the organophosphorus compound is 4-6 parts by weight, the content of the organic base is 15-22 parts by weight, the content of the water-soluble inorganic zinc salt is 8-12 parts by weight, and the content of water is 30-60 parts by weight.

[0036] According to the present invention, a low-phosphorus composite corrosion and scale inhibitor can be prepared by controlling the amount of organophosphorus compound in the composite corrosion and scale inhibitor, wherein the phosphate content is less than 2% by weight.

[0037] In this invention, the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite has the structure shown in formula (1).

[0038]

[0039] In the formula, n is 2-6, preferably 4, and x is 6-30, preferably 10-20.

[0040] The preparation method of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite includes: (1) contacting and reacting polyethylene glycol with thionyl chloride at 30℃-100℃ to obtain the intermediate ethylene sulfite; (2) contacting and reacting the long-chain alkyl-dimethyl tertiary amine with the intermediate ethylene sulfite in the presence of an organic solvent at 60℃-150℃ to obtain the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite.

[0041] In a preferred embodiment, the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite can be prepared by the following method:

[0042] (1) Add polyethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. Stir at medium speed and heat to a temperature range of 30℃-80℃. Add thionyl chloride dropwise using a dropping funnel at a rate of 10-50 drops / min. -1 After the thionamide is added dropwise, stir for 10 minutes, raise the temperature to 60℃-100℃ and react for 2-8 hours, then stop the reaction. Distill the obtained product under reduced pressure, and collect the distillate as the intermediate ethylene sulfite.

[0043] (2) Add long-chain alkyl dimethyl tertiary amine and dioxane solvent to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and reflux condenser. Stir at medium speed and add intermediate ethylene sulfite dropwise using a dropping funnel. Control the dropping temperature at 60℃~90℃ and the dropping rate at 5-30 drops·min. -1 After stirring for 10 minutes, the temperature was raised to 100-150℃, and the reaction was carried out for about 4-12 hours. The obtained product was subjected to vacuum distillation to remove the solvent, yielding long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite.

[0044] The molar ratio of polyethylene glycol to thionyl chloride is 1:1-3, preferably 1:1.

[0045] The molar ratio of the long-chain alkyl dimethyl tertiary amine to the intermediate ethylene sulfite is 1:1-3, preferably 1:1.

[0046] In this invention, the organophosphorus compound is selected from one or more of 2-hydroxyphosphonoacetic acid (HPAA), 2-phosphono-1,2,4-tricarboxylate butane (PBTC), and 1-hydroxyethyl-1,1-diphosphonic acid (HEDP).

[0047] In this invention, the water-soluble inorganic zinc salt is selected from at least one of zinc chloride, zinc nitrate, and zinc sulfate.

[0048] In this invention, the organic base is selected from at least one of ethanolamine, diethanolamine, and triethanolamine.

[0049] In this invention, the polycarboxylated polymer is selected from at least one of polyaspartic acid (PASP), polyepoxysuccinic acid (PESA), and hydrolyzed polymaleic anhydride (HPMA).

[0050] In this invention, the gluconate is selected from at least one of sodium gluconate, potassium gluconate, sodium D-gluconate, potassium D-gluconate, zinc gluconate, and manganese gluconate.

[0051] A second aspect of the present invention provides a method for preparing a composite corrosion and scale inhibitor, the method comprising: mixing the components of the composite corrosion and scale inhibitor described in the first aspect.

[0052] Preferably, the mixing conditions at least satisfy the following: temperature of 10-30℃, time of 0.5-1h, and stirring speed of 60-90rpm.

[0053] As previously stated, the third aspect of the present invention provides the application of the composite corrosion and scale inhibitor described in the first aspect in geothermal water corrosion and scale inhibition.

[0054] As mentioned above, a fourth aspect of the present invention provides a method for inhibiting corrosion and scale in geothermal water, the method comprising: adding the composite corrosion and scale inhibitor described in the first aspect to the geothermal water before the geothermal water is discharged from the well.

[0055] Preferably, the temperature of the geothermal water is >30°C. More preferably, the temperature of the geothermal water is 50-100°C.

[0056] Preferably, the mineralization of the geothermal water is 10,000-30,000 mg / L.

[0057] Preferably, the dissolved oxygen concentration of the geothermal water is >0.1 mg / L, and the dissolved oxygen concentration of the geothermal water is lower than the saturated dissolved oxygen concentration.

[0058] Preferably, based on the volume of the geothermal water, the amount of the composite corrosion and scale inhibitor added is 60-120 mg / L, more preferably 80-100 mg / L.

[0059] The present invention will be described in detail below through embodiments.

[0060] In the following examples, unless otherwise specified, all experimental instruments and raw materials involved are commercially available products.

[0061] Experimental instruments

[0062] Rotary wheel testing machine: SYZL-Ⅱ model, Gaoyou Qinyou Chemical Co., Ltd.;

[0063] raw material

[0064] Hexadecyl-dimethyl-tetraethylene glycol ammonium sulfite: self-made, the synthesis method is as follows: Add 0.2 mol of tetraethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and condenser, stir at medium speed, and add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min within a temperature range of 35-45℃. -1 After the thionyl chloride was added, the mixture was stirred for ten minutes, and the temperature was raised to 60-80℃ for 4 hours before the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of hexadecyl dimethyl tertiary amine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise using a dropping funnel at a temperature controlled at 60-70℃ and a dropping rate of 10 drops / min. -1 After stirring for ten minutes, the temperature was raised to 100-110℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding hexadecyl-dimethyl-tetraethylene glycol ammonium sulfite.

[0065] Hexadecyl-dimethyl-diethylene glycol ammonium sulfite: self-made, the synthesis method is as follows: Add 0.2 mol of diethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and a four-flow condenser, stir at medium speed, and add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min within a temperature range of 30-40°C. -1 After the thionyl chloride was added dropwise, the mixture was stirred for ten minutes. The temperature was then raised to 60-70℃ and the reaction was carried out for 4 hours, after which the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of hexadecyl dimethyl tertiary amine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise using a dropping funnel at a temperature controlled at 60-70℃ and a dropping rate of 10 drops / min. -1 After stirring for ten minutes, the temperature was raised to 100-110℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding hexadecyl-dimethyl-diethylene glycol ammonium sulfite.

[0066] Hexadecyl-dimethyl-hexaethylene glycol ammonium sulfite: self-made, the synthesis method is as follows: Add 0.2 mol of hexaethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and condenser, stir at medium speed, and add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min within a temperature range of 45-55℃. -1 After the thionyl chloride was added, the mixture was stirred for ten minutes, and the temperature was raised to 60-80℃ for 4 hours before the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of hexadecyl dimethyl tertiary amine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise using a dropping funnel at a temperature controlled at 60-80℃ and a dropping rate of 10 drops / min. -1 After stirring for ten minutes, the temperature was raised to 100-130℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding hexadecyl-dimethyl-hexaethylene glycol ammonium sulfite.

[0067] Hexaalkyl-dimethyl-tetraethylene glycol ammonium sulfite: self-made, the synthesis method is as follows: Add 0.2 mol of tetraethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and condenser, stir at medium speed, and add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min within a temperature range of 35-45℃. -1 After the thionyl chloride was added, the mixture was stirred for ten minutes, and the temperature was raised to 60-80℃ for 4 hours before the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of hexaalkyldimethyl tertiary amine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise using a dropping funnel at a temperature controlled at 60-70℃ and a dropping rate of 10 drops / min. -1 After stirring for ten minutes, the temperature was raised to 100-110℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding hexaalkyl-dimethyl-tetraethylene glycol ammonium sulfite.

[0068] Triacontyl-dimethyl-tetraethylene glycol ammonium sulfite: Prepared in-house, the synthesis method is as follows: Add 0.2 mol of tetraethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and a four-flow condenser. Stir at medium speed. At a temperature of 35–45°C, add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min. -1After the thionyl chloride was added, the mixture was stirred for ten minutes, and the temperature was raised to 60-80℃ for 4 hours before the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of triacontyl dimethyl tertiary amine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise through a dropping funnel at a temperature controlled at 60-70℃ at a dropping rate of 10 drops / min. -1 After stirring for ten minutes, the temperature was raised to 100-110℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding triacontyl-dimethyl-tetraethylene glycol ammonium sulfite.

[0069] Decyl-dimethyl-tetraethylene glycol ammonium sulfite: self-made, the synthesis method is as follows: Add 0.2 mol of tetraethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and a four-flow condenser, stir at medium speed, and add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min within a temperature range of 35–45°C. -1 After the thionyl chloride was added, the mixture was stirred for ten minutes, and the temperature was raised to 60-80℃ for 4 hours before the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of decaalkyldimethyl tertiary amine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise using a dropping funnel at a temperature controlled at 60-70℃ and a dropping rate of 10 drops / min. -1 After stirring for ten minutes, the temperature was raised to 100-110℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding decaalkyl-dimethyl-tetraethylene glycol ammonium sulfite.

[0070] Eicosyl-dimethyl-tetraethylene glycol ammonium sulfite: self-made, the synthesis method is as follows: Add 0.2 mol of tetraethylene glycol to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer and condenser, stir at medium speed, and add 0.2 mol of thionyl chloride dropwise using a dropping funnel at a rate of 25 drops / min within a temperature range of 35-45℃. -1 After the thionyl chloride was added, the mixture was stirred for ten minutes, and the temperature was raised to 60-80℃ for 4 hours before the reaction was stopped. The resulting product was subjected to vacuum distillation, and the fraction collected was the intermediate ethylene sulfite. 0.1 mol of eicosyldimethylamine and solvent were added to a dry four-necked flask equipped with a stirrer, dropping funnel, thermometer, and reflux condenser. The mixture was stirred at medium speed, and 0.1 mol of ethylene sulfite was added dropwise using a dropping funnel at a temperature controlled at 60-70℃ and a dropping rate of 10 drops / min.-1 After stirring for ten minutes, the temperature was raised to 100-110℃, and the reaction was carried out for 6 hours. The resulting product was then distilled under reduced pressure to remove the solvent, yielding eicosyl-dimethyl-tetraethylene glycol ammonium sulfite.

[0071] Cetyldimethyl(2-sulfite)ethylammonium: Ningbo Yinuo Chemical Co., Ltd.

[0072] Dodecyl dimethyl benzyl ammonium chloride: Shandong Taihe Water Treatment Technology Co., Ltd.;

[0073] Isothiazolinone: Shandong Taihe Water Treatment Technology Co., Ltd.;

[0074] Trichloroisocyanuric acid: Shandong Taihe Water Treatment Technology Co., Ltd.

[0075] PESA: Shandong Taihe Water Treatment Technology Co., Ltd.

[0076] HPMA: Shandong Taihe Water Treatment Technology Co., Ltd.

[0077] PASP: Shandong Taihe Water Treatment Technology Co., Ltd.

[0078] Sodium gluconate: Tianjin Damao Chemical Reagent Factory;

[0079] Potassium gluconate: Tianjin Damao Chemical Reagent Factory;

[0080] PBTC: Shandong Taihe Water Treatment Technology Co., Ltd.

[0081] HPAA: Shandong Taihe Water Treatment Technology Co., Ltd.

[0082] Ethanolamine: Tianjin Damao Chemical Reagent Factory;

[0083] Anhydrous zinc chloride: Tianjin Damao Chemical Reagent Factory;

[0084] Zinc sulfate: Tianjin Damao Chemical Reagent Factory;

[0085] Zinc nitrate: Tianjin Damao Chemical Reagent Factory.

[0086] In the following examples, the amounts of components are expressed in parts by weight. Unless otherwise specified, each part by weight represents 1g.

[0087] Examples 1-17

[0088] The formulation and process parameters of this embodiment are shown in Table 1, and the composite corrosion and scale inhibitors S1-S17 are prepared according to the method described below.

[0089] The method for preparing the composite corrosion and scale inhibitor includes the following steps:

[0090] At 25°C, the components of the composite corrosion and scale inhibitor composition were placed in a glass container and mixed for 1 hour at a rotation speed of 75 rpm to obtain composite corrosion and scale inhibitors S1-S17.

[0091] Unless otherwise specified, the remaining examples follow the same process as in Example 1, except that the formulation and process parameters of the composite corrosion and scale inhibitor composition are different, as detailed in Table 1.

[0092]

[0093] Comparative Examples 1-8

[0094] Comparative composite corrosion and scale inhibitors DS1-DS8 were prepared according to the formulation and process parameters in Table 2.

[0095] The SF0 structure is as follows:

[0096]

[0097] The structure of fungicide 1227 is as follows:

[0098]

[0099] The effective mass fraction of the bactericide in Table 2 is 10 parts.

[0100] Table 2

[0101]

[0102] Test Example 1

[0103] The performance of the composite corrosion and scale inhibitors obtained in each embodiment and comparative example was determined using the following test methods.

[0104] Dynamic corrosion tests were conducted using a rotary tester to simulate on-site conditions. The amount of composite corrosion and scale inhibitor added was 100 mg per liter of geothermal water. The test temperature was 70℃, the dissolved oxygen concentration was 1.0 mg / L, and the test time was 72 h.

[0105] The calcium hardness before and after the test was analyzed according to GB / T 16632-2019 "Determination of scale inhibition performance of water treatment agents - calcium carbonate deposition method" to calculate the calcium carbonate scale inhibition rate.

[0106] The formulas for calculating the corrosion inhibition rate and the calcium carbonate scale inhibition rate are as follows:

[0107]

[0108] In the formula, V0 represents the corrosion rate of the test piece without added corrosion and scale inhibitor, in mm / a.

[0109] V—Corrosion rate of the test piece after adding corrosion and scale inhibitor, mm / a.

[0110]

[0111] In the formula, ρ4 represents the Ca content of the test solution after adding scale and corrosion inhibitors. 2+ (Calculated as CaCO3) Mass concentration, mg / L;

[0112] ρ3—Ca after testing of the test solution without scale and corrosion inhibitors 2+ (Calculated as CaCO3) Mass concentration, mg / L;

[0113] ρ—Experimental water Ca 2+ (Calculated as CaCO3) Mass concentration, mg / L;

[0114] The test water was geothermal water from a region in Henan Province, with a temperature range of (50-100)℃ and a dissolved oxygen concentration >0.5mg / L. The water quality analysis results are shown in Table 3.

[0115] The performance test results of the composite corrosion and scale inhibitors in each embodiment and comparative example are shown in Table 4.

[0116] Table 3

[0117] project numerical values pH 7.03 Electrical conductivity (μS / cm) 20000 <![CDATA[Total alkalinity (calculated as CaCO3) / (mg / L)]]> 73.00 <![CDATA[Total hardness (calculated as CaCO3) / (mg / L)]]> 2625.00 <![CDATA[Calcium hardness (calculated as CaCO3) / (mg / L)]]> 2004.00 <![CDATA[Magnesium hardness (calculated as CaCO3) / (mg / L)]]> 621.00 <![CDATA[ρ(Cl - ) / (mg / L)]]> 11226.20 <![CDATA[ρ(SO4 2- ) / (mg / L)]]> 502.20 ρ(total iron) / (mg / L) 4.72 ρ(ammonia nitrogen, N) / (mg / L) 0.33 <![CDATA[ρ(Zn 2+ ) / (mg / L)]]> 0.85 <![CDATA[ρ(Soluble SiO2) / (mg / L)]]> 26.8

[0118] Table 4

[0119]

[0120]

[0121] The results above show that the composite corrosion and scale inhibitor provided by this invention has good corrosion and scale inhibition effects in geothermal water systems with medium and low temperature and oxygen-containing environments.

[0122] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite corrosion and scale inhibitor, comprising the following components: long-chain alkyl-dimethyl-polyethylene glycol sulfite, an organophosphorus compound, an organic base, a water-soluble inorganic zinc salt, and water, wherein, relative to 100 parts by weight of the composite corrosion and scale inhibitor, the content of the long-chain alkyl-dimethyl-polyethylene glycol sulfite is 5-15 parts by weight, the content of the organophosphorus compound is 2-10 parts by weight, the content of the organic base is 12-25 parts by weight, and the content of the water-soluble inorganic zinc salt is 4-15 parts by weight, wherein... The long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite has the structure shown in the following formula. In the formula, n is 2-6 and x is 6-30.

2. The composite corrosion and scale inhibitor according to claim 1, further comprising one or two of a polycarboxylated polymer and gluconate.

3. The composite corrosion and scale inhibitor according to claim 2, wherein, The content of the polycarboxylated polymer and the content of the gluconate are 0-15 parts by weight relative to 100 parts by weight of the composite corrosion and scale inhibitor.

4. The composite corrosion and scale inhibitor according to claim 2, wherein, Relative to 100 parts by weight of the composite corrosion and scale inhibitor, the content of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite is 8-12 parts by weight, the content of the polycarboxyl polymer is 2-12 parts by weight, the content of the gluconate is 2-12 parts by weight, the content of the organophosphorus compound is 4-6 parts by weight, the content of the organic base is 15-22 parts by weight, the content of the water-soluble inorganic zinc salt is 8-12 parts by weight, and the content of water is 30-60 parts by weight.

5. The composite corrosion and scale inhibitor according to claim 1 or 2, wherein, In the structural formula of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite, n is 4 and x is 10-20.

6. The composite corrosion and scale inhibitor according to claim 1, wherein, The preparation method of the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite includes: (1) contacting and reacting polyethylene glycol with thionyl chloride at 30℃-100℃ to obtain the intermediate ethylene sulfite; (2) contacting and reacting the long-chain alkyl-dimethyl tertiary amine with the intermediate ethylene sulfite in the presence of an organic solvent at 60℃-150℃ to obtain the long-chain alkyl-dimethyl-polyethylene glycol ammonium sulfite.

7. The composite corrosion and scale inhibitor according to claim 1 or 2, wherein, The organophosphorus compound is selected from one or more of 2-hydroxyphosphonoacetic acid, 2-phosphono-1,2,4-tricarboxylate butane, and 1-hydroxyethyl-1,1-diphosphonic acid.

8. The composite corrosion and scale inhibitor according to claim 1 or 2, wherein, The water-soluble inorganic zinc salt is selected from at least one of zinc chloride, zinc nitrate, and zinc sulfate.

9. The composite corrosion and scale inhibitor according to claim 1 or 2, wherein, The organic base is selected from at least one of ethanolamine, diethanolamine, and triethanolamine.

10. The composite corrosion and scale inhibitor according to claim 2, wherein, The polycarboxylated polymer is selected from at least one of polyaspartic acid, polyepoxysuccinic acid, and hydrolyzed polymaleic anhydride.

11. The composite corrosion and scale inhibitor according to claim 2, wherein, The gluconate is selected from at least one of sodium gluconate, potassium gluconate, sodium D-gluconate, potassium D-gluconate, zinc gluconate, and manganese gluconate.

12. A method for preparing a composite corrosion and scale inhibitor, the method comprising: The components of the composite corrosion and scale inhibitor described in claim 1 or 2 are mixed.

13. The application of the composite corrosion and scale inhibitor as described in claim 1 or 2 in geothermal water corrosion and scale inhibition.

14. A method for inhibiting corrosion and scale in geothermal water, comprising: Before the geothermal water is discharged from the well, the composite corrosion and scale inhibitor described in claim 1 or 2 is added to the geothermal water.

15. The method according to claim 14, wherein, Based on the volume of the geothermal water, the amount of the composite corrosion and scale inhibitor added is 60-120 mg / L.

16. The method according to claim 14, wherein, Based on the volume of the geothermal water, the amount of the composite corrosion and scale inhibitor added is 80-100 mg / L.

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