Composite sulfur scavenger and method for its preparation

Abstract

The present application relates to the technical field of crude oil hydrogen sulfide treatment, and is a composite sulfur removal agent and a preparation method thereof.The raw materials of the composite sulfur removal agent include, in terms of mass fraction, 35-42 parts of monoethanolamine, 20-25 parts of polyformaldehyde, 3-5 parts of ethanol, 2-8 parts of high-efficiency scale inhibitor, 2-8 parts of composite synergist, 2-8 parts of wetting dispersant, and 6-12 parts of hydrogen peroxide.The composite sulfur removal agent is prepared by one-pot method, the raw materials are easy to obtain, and the components have good compatibility, the reaction time is short, the permeability is good, and the hydrogen sulfide content in the produced liquid of the oil well can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen sulfide treatment of crude oil, and is a composite sulfur removal agent and a preparation method thereof. BACKGROUND

[0002] In recent years, due to the presence of hydrogen sulfide in the process of oil and gas well exploitation and transportation, corrosion will be caused to oil pipes, casings, pumps, oil gathering pipelines and other equipment, resulting in huge economic losses. Meanwhile, the presence of hydrogen sulfide brings huge safety hazards to construction workers, and the leakage of hydrogen sulfide directly threatens the life and property safety of construction workers. The sources of hydrogen sulfide in oil and gas well production are: first, the sulfides existing in the formation are dissolved in oil and gas and brought to the ground with oil and gas exploitation; second, due to the presence of sulfate-reducing bacteria, SO4 2- in the produced fluid of the formation is reduced to S 2- .

[0003] At present, the sulfur removal agent is used for sulfur removal construction of the produced fluid of oil and gas wells, which is a kind of technology widely used and effective in oilfields. Different types of sulfur removal agents have different sulfur removal mechanisms. Common sulfur removal agents include organic amine sulfur removal agents, heterocyclic sulfur removal agents and triazine sulfur removal agents. In the process of using the existing sulfur removal agents on site, the mixing degree of the sulfur removal agent and the produced fluid determines the effect of the agent reaction. The triazine sulfur removal agent has no special irritating odor, low toxicity, forms a soluble compound by reacting with hydrogen sulfide, and has excellent sulfur removal performance, so it is widely used. However, the triazine sulfur removal agent is easy to hydrolyze in a low-concentration and low-pH environment, the product is easy to scale, and the effect of the agent is obviously reduced. When used in the oil-casing annulus, the effect is different under different working conditions. In the self-flowing well and the pumping well, the mixing mode after adding the agent is different, and the final amount of the agent and the effect of the agent are obviously different. When used in the ground pipeline, the agent is not easy to mix uniformly due to the limitation of the adding conditions, the penetration and diffusion of the agent are slow, the reaction time is long, and the sulfur removal effect is not ideal. SUMMARY

[0004] The present application provides a composite sulfur removal agent and a preparation method thereof, which overcomes the shortcomings of the prior art and effectively solves the problems of slow penetration and diffusion of the existing sulfur removal agent, long reaction time and poor sulfur removal effect.

[0005] One of the technical solutions of the present application is realized by the following measures: a composite sulfur removal agent, raw materials including, by mass fraction: monoethanolamine 35-42 parts, polyformaldehyde 20-25 parts, ethanol 3-5 parts, high-efficiency scale inhibitor 2-8 parts, composite synergist 2-8 parts, wetting dispersant 2-8 parts, and hydrogen peroxide 6-12 parts.

[0006] The following are further optimizations and / or improvements to the above-mentioned technical solution:

[0007] The aforementioned high-efficiency scale inhibitors are organophosphate scale inhibitors, specifically aminotrimethylenephosphonic acid or hydroxyethylidene diphosphonic acid.

[0008] The aforementioned compound synergist is ammonium dodecylbenzenesulfonate.

[0009] The above wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0010] The above-mentioned composite desulfurizing agent is prepared by the following method:

[0011] First, after purging the air from the reactor, add a portion of monoethanolamine and the required amount of ethanol to the reactor under vacuum conditions, and stir to mix evenly.

[0012] The second step is to add the required amount of paraformaldehyde to the reactor and react it under the required conditions.

[0013] Third, after the reaction in the second step is completed, add the remaining amount of monoethanolamine into the reaction vessel again;

[0014] Fourth step: When the reactor temperature reaches the required temperature, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide to carry out the reaction. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0015] In the first step above, the amount of monoethanolamine added is 65% to 75% of the total amount.

[0016] In the second step above, the reaction conditions are a reaction temperature of 50°C to 55°C and a reaction time of 2 to 4 hours.

[0017] In the third step above, after the second step reaction is completed, when the reaction vessel cools down to 40°C to 45°C, the remaining amount of monoethanolamine is added to the reaction vessel again.

[0018] In the fourth step above, when the temperature of the reactor reaches 30°C to 45°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 25 to 35 minutes. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0019] The second technical solution of the present invention is achieved through the following measures: a method for preparing a composite desulfurizing agent, comprising the following steps:

[0020] First, after purging the air from the reactor, add a portion of monoethanolamine and the required amount of ethanol to the reactor under vacuum conditions, and stir to mix evenly.

[0021] The second step is to add the required amount of paraformaldehyde to the reactor and react it under the required conditions.

[0022] Third, after the reaction in the second step is completed, add the remaining amount of monoethanolamine into the reaction vessel again;

[0023] Fourth step: When the reactor temperature reaches the required temperature, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide to carry out the reaction. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0024] The composite desulfurizing agent of the present invention is prepared by a one-pot method. The raw materials are readily available and the components have good compatibility. The reaction time is short and the permeability is good, which can effectively reduce the hydrogen sulfide content in the produced fluid of oil wells. Detailed Implementation

[0025] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0026] The present invention will be further described below with reference to embodiments:

[0027] Example 1: The raw materials of the composite desulfurizing agent include, by mass parts: 35 to 42 parts monoethanolamine, 20 to 25 parts paraformaldehyde, 3 to 5 parts ethanol, 2 to 8 parts high-efficiency scale inhibitor, 2 to 8 parts composite synergist, 2 to 8 parts wetting and dispersing agent, and 6 to 12 parts hydrogen peroxide.

[0028] Example 2: As an optimization of the above example, the high-efficiency scale inhibitor is an organophosphate scale inhibitor, specifically aminotrimethylene phosphonic acid or hydroxyethylidene diphosphonic acid.

[0029] Example 3: As an optimization of the above examples, the composite synergist is ammonium dodecylbenzenesulfonate. Ammonium dodecylbenzenesulfonate has strong neutralizing ability, dispersing effect, corrosion inhibition effect, and additional degreasing effect.

[0030] Example 4: As an optimization of the above examples, the wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0031] Example 5: As an optimization of the above examples, the composite desulfurizer was prepared by the following method:

[0032] First, after purging the air from the reactor, add a portion of monoethanolamine and the required amount of ethanol to the reactor under vacuum conditions, and stir to mix evenly.

[0033] The second step is to add the required amount of paraformaldehyde to the reactor and react it under the required conditions.

[0034] Third, after the reaction in the second step is completed, add the remaining amount of monoethanolamine into the reaction vessel again;

[0035] Fourth step: When the reactor temperature reaches the required temperature, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide to carry out the reaction. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0036] Example 6: As an optimization of the above example, in the first step, the amount of monoethanolamine added is 65% to 75% of the total amount.

[0037] Example 7: As an optimization of the above example, in the second step, the reaction conditions are a reaction temperature of 50°C to 55°C and a reaction time of 2 hours to 4 hours.

[0038] Example 8: As an optimization of the above example, in the third step, after the reaction in the second step is completed, when the reaction vessel is cooled to 40°C to 45°C, the remaining amount of monoethanolamine is added to the reaction vessel again.

[0039] Example 9: As an optimization of the above example, in the fourth step, when the temperature of the reactor reaches 30°C to 45°C, the required amount of high-efficiency scale inhibitor and composite synergist are added to the reactor in sequence. After stirring and mixing evenly, hydrogen peroxide is added, and the reaction is carried out for 25 minutes to 35 minutes. After the reaction is completed, the required amount of wetting and dispersing agent is added, and the mixture is stirred and mixed evenly to obtain the composite desulfurizing agent.

[0040] The composite desulfurizing agent of this invention is prepared using a one-pot method. A preliminary desulfurizing agent is obtained by reacting monoethanolamine with paraformaldehyde, followed by the addition of other reagents to obtain the composite desulfurizing agent. Monoethanolamine in the raw materials contains hydroxyl and amino groups, thus enabling it to undergo reactions characteristic of alcohols and amines. Paraformaldehyde has a higher effective content than formaldehyde, and as a solid particle, it is more suitable for chemical synthesis in chemical and pharmaceutical industries and other industrial applications. This invention mainly utilizes its desulfurization properties and high purity. Ethanol in the raw materials is used to depolymerize paraformaldehyde and improves the permeability of the agent in the produced fluid, accelerating the reaction time. The highly efficient scale inhibitor is an organophosphate scale inhibitor, which has excellent dispersing and integrating effects on calcium carbonate, calcium sulfate, etc., in water, and can be used for scale inhibition in formations and pipelines during oil production, preventing blockages caused by scaling. The composite synergist is ammonium dodecylbenzenesulfonate, which utilizes its acid-base balance to increase the reaction rate. Wetting and dispersing agents facilitate rapid dispersion of reagent components in the oil or aqueous phase, reverse wetting, increase the desulfurization reaction rate, and ensure a more complete reaction. In the fourth step of the preparation method, adding hydrogen peroxide can improve product recovery. Hydrogen peroxide can also continue to react with unreacted formaldehyde, eliminating residual formaldehyde in the synthesized desulfurizing agent. Furthermore, hydrogen peroxide also has a certain bactericidal effect, effectively inhibiting sulfate-reducing bacteria and removing SO4 from the formation produced fluid. 2- Equal to S 2- The composite desulfurizing agent of this invention can solve the problem of uneven mixing of agents during the production process and can effectively shorten the desulfurization reaction time.

[0041] Example 10: The composite desulfurizing agent comprises, by weight, the following raw materials: 40 parts monoethanolamine, 25 parts paraformaldehyde, 4 parts ethanol, 8 parts high-efficiency scale inhibitor, 6 parts composite synergist, 5 parts wetting and dispersing agent, and 10 parts hydrogen peroxide. In this example, the high-efficiency scale inhibitor is aminotrimethylene phosphonic acid, the composite synergist is ammonium dodecylbenzenesulfonate, and the wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0042] The preparation process of this composite desulfurizing agent is as follows:

[0043] First, purge the reactor with nitrogen to remove all air, then dry the reactor. Under vacuum conditions, add 70% of the required total amount of monoethanolamine and the required amount of ethanol to the reactor and stir until homogeneous.

[0044] The second step involves slowly adding a measured amount of paraformaldehyde to the top of the reactor. The reactor temperature must not exceed 55°C. If the temperature rises too quickly, immediately stop adding the material. Slowly add the measured amount of paraformaldehyde while keeping the temperature below 55°C. After adding the paraformaldehyde, maintain the temperature between 50°C and 55°C for 2 hours.

[0045] The third step is to add the remaining amount of monoethanolamine to the reactor when the temperature drops to 45°C.

[0046] In the fourth step, when the temperature of the reactor reaches 40°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 30 minutes. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0047] Example 11: The composite desulfurizing agent comprises the following raw materials by mass: 42 parts monoethanolamine, 25 parts paraformaldehyde, 3 parts ethanol, 6 parts high-efficiency scale inhibitor, 4 parts composite synergist, 8 parts wetting and dispersing agent, and 12 parts hydrogen peroxide. In this example, the high-efficiency scale inhibitor is hydroxyethylidene diphosphonic acid, the composite synergist is ammonium dodecylbenzenesulfonate, and the wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0048] The preparation process of this composite desulfurizing agent is as follows:

[0049] First, purge the reactor with nitrogen to remove all air, then dry the reactor. Under vacuum conditions, add 70% of the required total amount of monoethanolamine and the required amount of ethanol to the reactor and stir until homogeneous.

[0050] The second step is to slowly add a metered amount of paraformaldehyde to the top of the reactor. The reactor temperature should not exceed 55°C. If the temperature rises too quickly, stop adding the material immediately. Slowly add the metered amount of paraformaldehyde while keeping the temperature below 55°C. After adding the paraformaldehyde, keep the temperature between 50°C and 55°C for 2.5 hours.

[0051] The third step is to add the remaining amount of monoethanolamine to the reactor when the temperature drops to 45°C.

[0052] In the fourth step, when the temperature of the reactor reaches 35°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 30 minutes. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0053] Example 12: The composite desulfurizing agent comprises, by weight, the following raw materials: 35 parts monoethanolamine, 20 parts paraformaldehyde, 5 parts ethanol, 8 parts high-efficiency scale inhibitor, 8 parts composite synergist, 8 parts wetting and dispersing agent, and 12 parts hydrogen peroxide. In this example, the high-efficiency scale inhibitor is aminotrimethylene phosphonic acid, the composite synergist is ammonium dodecylbenzenesulfonate, and the wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0054] The preparation process of this composite desulfurizing agent is as follows:

[0055] First, purge the reactor with nitrogen to remove all air, then dry the reactor. Under vacuum conditions, add 70% of the required total amount of monoethanolamine and the required amount of ethanol to the reactor and stir until homogeneous.

[0056] The second step is to slowly add a metered amount of paraformaldehyde to the top of the reactor. The reactor temperature should not exceed 55°C. If the temperature rises too quickly, stop adding the material immediately. Slowly add the metered amount of paraformaldehyde while keeping the temperature below 55°C. After adding the paraformaldehyde, keep the temperature between 50°C and 55°C for 2 hours.

[0057] The third step is to add the remaining amount of monoethanolamine to the reactor when the temperature drops to 45°C.

[0058] In the fourth step, when the temperature of the reactor reaches 35°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 30 minutes. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0059] Example 13: The composite desulfurizing agent comprises the following raw materials by mass percentage: 38 parts monoethanolamine, 25 parts paraformaldehyde, 5 parts ethanol, 8 parts high-efficiency scale inhibitor, 8 parts composite synergist, 5 parts wetting and dispersing agent, and 10 parts hydrogen peroxide. In this example, the high-efficiency scale inhibitor is hydroxyethylidene diphosphonic acid, the composite synergist is ammonium dodecylbenzenesulfonate, and the wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0060] The preparation process of this composite desulfurizing agent is as follows:

[0061] First, purge the reactor with nitrogen to remove all air, then dry the reactor. Under vacuum conditions, add 70% of the required total amount of monoethanolamine and the required amount of ethanol to the reactor and stir until homogeneous.

[0062] The second step is to slowly add a metered amount of paraformaldehyde to the top of the reactor. The reactor temperature should not exceed 55°C. If the temperature rises too quickly, stop adding the material immediately. Slowly add the metered amount of paraformaldehyde while keeping the temperature below 55°C. After adding the paraformaldehyde, keep the temperature between 50°C and 55°C for 3 hours.

[0063] The third step is to add the remaining amount of monoethanolamine to the reactor when the temperature drops to 45°C.

[0064] In the fourth step, when the temperature of the reactor reaches 35°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 30 minutes. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

[0065] Comparative Example 1: Chemicals used on-site at vehicle 510: Commercially available organic amine desulfurizer.

[0066] Comparative Example 2: Chemicals used on-site at Che89: Commercially available triazine desulfurizer.

[0067] Performance evaluation of composite desulfurizer 1:

[0068] The composite desulfurizing agents obtained in Examples 10 to 13 and the desulfurizing agents in Comparative Examples 1 and 2 were used to conduct desulfurization tests on sulfur-containing oil wells in Xinjiang Oilfield. The residual hydrogen sulfide concentration was measured at 5 min, 30 min, 60 min, and 90 min after desulfurization, and the experimental results are shown in Table 1. According to the technical specifications of "Q / SY XJ0294-2019 Technical Specification for Hydrogen Sulfide Treatment Agents for Oil and Gas Gathering and Transportation," the soluble sulfide removal rate and sulfur solubility technical indicators of the composite desulfurizing agents obtained in Examples 10 to 13 and Comparative Examples 1 and 2 were tested, and the test results are shown in Table 1. As shown in Table 1, the residual hydrogen sulfide concentration of the composite desulfurizing agent of the present invention at 30 min and 60 min after desulfurization is significantly lower than that of the on-site agent, indicating that the composite desulfurizing agent of the present invention has better permeability and diffusion than existing desulfurizing agents. The composite desulfurizing agent of the present invention has a higher hydrogen sulfide removal rate and higher sulfur solubility than the desulfurizing agents in Comparative Examples 1 and 2, indicating that the composite desulfurizing agent of the present invention has excellent desulfurization effect.

[0069] Performance evaluation of composite desulfurizer, part two:

[0070] The hydrogen sulfide removal rate was compared between the desulfurizing agent (triazine desulfurizing agent) used in the oilfield and the composite desulfurizing agent prepared in Example 10 of this invention.

[0071] Taking the Sixth Oil Production Area of ​​the No. 1 Oil Production Plant in Karamay Oilfield as an example, the concentration of hydrogen sulfide in the produced fluid in a single well can reach over 1000 ppm during oilfield development, which restricts crude oil extraction in this area. Experiments were conducted using the composite desulfurizing agent prepared in Example 10 of this invention, with the desulfurizing agent used in the production area as a reference. The hydrogen sulfide concentration in the produced fluid was over 1000 ppm, and the produced fluid temperature was around 70℃.

[0072] Referring to the People's Republic of China Petroleum and Natural Gas Industry Standard "Q / SY XJ0294-2019 Technical Specification for Hydrogen Sulfide Treatment Agent for Oil and Gas Gathering and Transportation" and the Xinkeao Enterprise Standard "Q / XKA 603-2021 Hydrogen Sulfide Treatment Agent for Oilfield Use", an evaluation test of the desulfurizing agent was conducted on the produced fluid of the Sixth Oil Production Area of ​​Karamay Oilfield No. 1 Plant at a temperature of 70℃. The experimental results are shown in Table 2. As can be seen from Table 2, the composite desulfurizing agent prepared in this invention has a better effect on removing hydrogen sulfide in the field at the Sixth Oil Production Area of ​​Karamay Oilfield No. 1 Plant than the desulfurizing agent used in the field.

[0073] Quality testing of composite desulfurizer:

[0074] The composite desulfurizing agent of this invention has excellent performance and meets the standard requirements of both "Q / SY XJ0294-2019 Technical Specification for Hydrogen Sulfide Treatment Agent for Oil and Gas Gathering and Transportation" and "Q / XKA 603-2021 Hydrogen Sulfide Treatment Agent for Oilfield Use". The test indicators are shown in Table 3.

[0075] The composite desulfurizing agent prepared by this invention has the characteristics of high desulfurization efficiency, low dosage, water solubility, good dispersibility, non-corrosiveness and non-scaling, and the ability to simultaneously inject the desulfurizing agent into oil pipelines to significantly remove H2S from the oil, gas and water phases of crude oil. The high H2S absorption capacity of the desulfurizing agent can effectively reduce environmental pollution and has broad application prospects in oil and gas field development.

[0076] In summary, the composite desulfurizing agent of this invention can effectively remove hydrogen sulfide from oil well produced fluid, with a short reaction time, good permeability, and good compatibility with produced fluid. It can effectively reduce the hydrogen sulfide content in oil well produced fluid. The raw materials of this invention are readily available and the components have good compatibility, resulting in a significant desulfurization effect.

[0077] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A composite desulfurizing agent, characterized in that... The raw materials, by mass parts, include: 35 to 42 parts monoethanolamine, 20 to 25 parts paraformaldehyde, 3 to 5 parts ethanol, 2 to 8 parts high-efficiency scale inhibitor, 2 to 8 parts compound synergist, 2 to 8 parts wetting and dispersing agent, and 6 to 12 parts hydrogen peroxide; wherein, the compound synergist is ammonium dodecylbenzenesulfonate. The composite desulfurizing agent is prepared according to the following method: First, after purging the air from the reactor, add a portion of monoethanolamine and the required amount of ethanol to the reactor under vacuum conditions, and stir to mix evenly. The second step is to add the required amount of paraformaldehyde to the reactor and react it under the required conditions. Third, after the reaction in the second step is completed, add the remaining amount of monoethanolamine into the reaction vessel again; Fourth step: When the reactor temperature reaches the required temperature, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide to carry out the reaction. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

2. The composite desulfurizing agent according to claim 1, characterized in that... Highly effective scale inhibitors are organophosphate scale inhibitors, specifically aminotrimethylene phosphonic acid or hydroxyethylidene diphosphonic acid.

3. The composite desulfurizing agent according to claim 1 or 2, characterized in that... The wetting and dispersing agent is dodecylbenzenesulfonic acid.

4. The composite desulfurizing agent according to claim 1, characterized in that... In the first step, the amount of monoethanolamine added is 65% to 75% of the total amount.

5. The composite desulfurizing agent according to claim 1 or 4, characterized in that... In the second step, the reaction conditions are a reaction temperature of 50°C to 55°C and a reaction time of 2 to 4 hours.

6. The composite desulfurizing agent according to claim 5, characterized in that... In the third step, after the reaction in the second step is completed, when the temperature of the reactor drops to 40°C to 45°C, the remaining amount of monoethanolamine is added to the reactor again.

7. The composite desulfurizing agent according to claim 1, 4, or 6, characterized in that... In the fourth step, when the temperature of the reactor reaches 30℃ to 45℃, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 25min to 35min. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

8. A method for preparing a composite desulfurizing agent according to any one of claims 1 to 7, characterized in that... Follow these steps: First, after purging the air from the reactor, add a portion of monoethanolamine and the required amount of ethanol to the reactor under vacuum conditions, and stir to mix evenly. The second step is to add the required amount of paraformaldehyde to the reactor and react it under the required conditions. Third, after the reaction in the second step is completed, add the remaining amount of monoethanolamine into the reaction vessel again; Fourth step: When the reactor temperature reaches the required temperature, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide to carry out the reaction. After the reaction is completed, add the required amount of wetting and dispersing agent, stir and mix evenly to obtain the composite desulfurizer.

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