Liquid sulfur removal agent and preparation method thereof

Abstract

The invention provides a liquid sulfur removal agent and a preparation method thereof, and belongs to the technical field of natural gas hydrogen sulfide removal treatment.The liquid sulfur removal agent comprises, by weight, 36-66% of s-triazine derivatives, 5-8% of sulfolane, 2-5% of a pH control agent, 10-12% of a stabilizer, 5-8% of a scale inhibitor, 1-2% of a bactericide and the balance deionized water; wherein the s-triazine derivative is selected from a mixture of hexahydro-1, 3, 5-triacetyl-hexahydros-triazine, 1, 3, 5-triacetyl-hexahydros-triazine and 1, 3, 5-triazinane-2, 4-diketone, and the structural formula of the s-triazine derivative is shown in the description. The liquid sulfur removal agent is high in sulfur removal efficiency, good in corrosion inhibition and sterilization performance and not prone to scaling.

Description

Technical Field

[0001] This invention relates to the field of natural gas desulfurization and hydrogen sulfide treatment technology, specifically to a liquid desulfurizing agent and its preparation method. Background Technology

[0002] Currently, commonly used desulfurizing agents for hydrogen sulfide removal from natural gas include calcium carbonate salts, alkanolamine desulfurizers, and triazine desulfurizers. Among these, water-soluble triazine desulfurizers synthesized from alkanolamines and aldehydes offer superior desulfurization efficiency compared to conventional alkanolamine desulfurizers. They are easy to prepare industrially, the products are water-soluble, low in toxicity, and possess bactericidal properties, reducing equipment corrosion and are environmentally friendly. They also have advantages such as low equipment requirements, ease of operation, and low cost during industrial use. However, water-soluble triazine desulfurizers synthesized from alkanolamines and aldehydes are prone to hydrolysis in low pH environments and precipitation at high hydrogen sulfide concentrations. The formation of precipitates leads to decreased sulfur removal efficiency and may clog pipelines, affecting normal production. Early applications in gas storage facilities such as the Suqiao Gas Storage Facility and the Sichuan-Chongqing Gas Field have shown instances of calcium and magnesium ions in the produced fluid combining with the triazine desulfurizer to form precipitates and clog pipelines, indicating poor process adaptability.

[0003] To address the aforementioned issues, those skilled in the art urgently need to provide a desulfurizing agent that is highly efficient and does not easily form scale. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid desulfurizing agent to solve the problems of precipitates and poor process adaptability under conditions of high calcium and magnesium concentrations and high hydrogen sulfide content.

[0005] This invention provides a method for preparing a liquid desulfurizing agent, which can solve the above-mentioned technical problems.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] This invention provides a liquid desulfurizing agent, comprising by weight percentage: 36-66% triazine derivatives, 5-8% sulfolane, 2-5% pH control agent, 10-12% stabilizer, 5-8% scale inhibitor, 1-2% bactericide, and the balance being deionized water;

[0008] Among them, the triazine derivatives are selected as a mixture of hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine and 1,3,5-triazine-2,4-dione.

[0009] The liquid desulfurizing agent as described above, wherein, by weight percentage, 16-30% hydroxyethyl hexahydrotriazine, 10-18% 1,3,5-triacetyl hexahydrotriazine, and 10-18% 1,3,5-triazine-2,4-dione.

[0010] The liquid desulfurizer as described above contains 24-30% hydroxyethyl hexahydrotriazine, 12-15% 1,3,5-triacetyl hexahydrotriazine, and 12-15% 1,3,5-triazine-2,4-dione.

[0011] The liquid desulfurizing agent as described above, wherein the pH control agent makes the pH value of the liquid desulfurizing agent 8-10.

[0012] The liquid desulfurizing agent described above contains a pH control agent that is either disodium hydrogen phosphate or sodium bicarbonate.

[0013] The liquid desulfurizer described above, wherein the stabilizer is at least one of diethyl methylphosphonate and diethyl ethylphosphonate.

[0014] The liquid desulfurizing agent as described above, wherein the scale inhibitor is at least one of sodium polymethacrylate and potassium polymethacrylate.

[0015] The liquid desulfurizing agent described above contains a bactericide selected from allylthiazole, sodium cresol, and sodium hypochlorite.

[0016] The present invention also provides a method for preparing a liquid desulfurizing agent, wherein the steps are as follows: weigh the above raw materials, mix and stir evenly to obtain a liquid desulfurizing agent.

[0017] The preparation method of the liquid desulfurizing agent as described above includes the following steps:

[0018] S1. Deionized water, scale inhibitor and pH control agent are added to the reaction vessel in sequence, stirred evenly and cooled to room temperature.

[0019] S2, 1,3,5-triazine-2,4-dione is slowly added to the above aqueous solution under stirring. After complete dissolution, hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine and sulfolane are added slowly in sequence, and stirring is continued until homogeneous.

[0020] S3, add the stabilizer and bactericide to the above reaction vessel, mix and stir to obtain the liquid desulfurizer;

[0021] The stirring time in S1 is 10-30 min, followed by cooling for 2 h; the mixing time in S2 is 20-30 min; and the mixing time in S3 is 25-35 min.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] This invention utilizes a mixture of hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine, and 1,3,5-triazine-2,4-dione as a desulfurizing agent, combined with sulfolane, pH control agents, and scale inhibitors, to obtain a liquid desulfurizing agent. This agent can operate without producing precipitates under conditions of high calcium, high magnesium concentrations, and high hydrogen sulfide content. It also exhibits excellent corrosion inhibition and bactericidal functions, avoiding the hydrolysis of triazine caused by low pH environments. Simultaneously, it maintains high hydrogen sulfide removal efficiency, with a fast reaction rate and high selectivity. Compared to traditional triazine desulfurizing agents, it has stronger process adaptability and can be used for pipeline injection and spray injection to remove hydrogen sulfide and organic sulfur. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] On the one hand, the present invention provides a liquid desulfurizing agent, comprising by weight percentage: 36-66% triazine derivatives, 5-8% sulfolane, 2-5% pH control agent, 10-12% stabilizer, 5-8% scale inhibitor, 1-2% bactericide, and the balance being deionized water;

[0026] Among them, the triazine derivatives are selected as a mixture of hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine and 1,3,5-triazine-2,4-dione.

[0027] This invention utilizes a mixture of hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine, and 1,3,5-triazine-2,4-dione as a desulfurizing agent, combined with sulfolane, pH control agents, scale inhibitors, etc., to obtain a liquid desulfurizing agent. This agent can operate without producing precipitates under conditions of high calcium, high magnesium concentrations, and high hydrogen sulfide content. It also exhibits excellent corrosion inhibition and bactericidal functions, avoids the hydrolysis of triazine caused by low pH environments, maintains high hydrogen sulfide removal efficiency, has a fast reaction rate, high selectivity, and stronger process adaptability.

[0028] Specifically, in the liquid desulfurizer, by weight percentage, there are 16-30% hydroxyethyl hexahydrotriazine, 10-18% 1,3,5-triacetyl hexahydrotriazine, and 10-18% 1,3,5-triazine-2,4-dione.

[0029] In the natural gas desulfurizer market, triazine desulfurizer is one of the main liquid desulfurizers. Triazine derivatives belong to a type of cyclic amine. Triazine molecules can react rapidly with H2S to form thiadiazine, and thiadiazine can further react slowly with another H2S molecule to form dithiazine. The removal of hydrogen sulfide by triazine desulfurizers is a chemical reaction that is irreversible. They are mainly suitable for the removal of low concentrations of H2S, typically less than 200 mg / L. Compared with conventional alkanolamine desulfurizers, triazine desulfurizers have good desulfurization efficiency, are easy to prepare industrially, the product is water-soluble, low in toxicity, has bactericidal properties, is environmentally friendly, and has low equipment requirements, is easy to operate, and is inexpensive in industrial use. However, triazine desulfurizers are prone to hydrolysis in low pH environments, and precipitation is likely to occur in environments with high divalent cation content. Under certain operating conditions with high hydrogen sulfide content, a large amount of white precipitate may also form.

[0030] Hydroxyethyl hexahydrotriazine exhibits specificity for rapid absorption of hydrogen sulfide, with a fast reaction rate that allows for immediate reaction upon contact at suitable concentrations. 1,3,5-Triacetyl hexahydrotriazine demonstrates strong absorption capacity for hydrogen sulfide and is less prone to scaling, but its reaction rate is lower than that of hydroxyethyl hexahydrotriazine. 1,3,5-Triazine-2,4-dione exhibits good high-temperature resistance and oxidation resistance. The synergistic effect of these three components ensures high desulfurization efficiency while reducing the risks of scaling and high-temperature hydrolysis, thus improving the desulfurizer's process adaptability.

[0031] By introducing 1,3,5-triacetylhexahydrotriazine, the risk of scaling due to localized overheating caused by the reaction of the desulfurizing agent with hydrogen sulfide is reduced. Furthermore, the addition of polymethacrylate inhibits the scaling risk of calcium and magnesium scale salts, thus enabling the absence of precipitates under conditions of high calcium, high magnesium concentrations, and high hydrogen sulfide content.

[0032] Hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine, and 1,3,5-triazine-2,4-dione all possess bactericidal properties and can even be used alone as bactericides in certain environments. When combined with other bactericides, their bactericidal and adaptability properties are greatly improved. Furthermore, hydroxyethyl hexahydrotriazine and 1,3,5-triacetyl hexahydrotriazine exhibit good corrosion inhibition properties under stable conditions, as reported in the literature and further demonstrated in subsequent experimental examples.

[0033] In field applications, for sulfur-containing raw gas with a certain pipeline length (usually greater than 400m), the desulfurizing agent can be directly added to the pipeline, using the pipeline itself as a desulfurization reactor. The advantages are that it increases equipment investment costs almost entirely, does not increase land occupation, and has low desulfurization costs. For some single wells without external pipelines, where there is not enough pipeline length to serve as a desulfurization reactor, a desulfurization reaction device needs to be built on-site for desulfurization via spraying. The desulfurizing agent provided by this invention is characterized by its resistance to scaling, good temperature resistance, and high desulfurization efficiency, offering better process adaptability compared to traditional triazine desulfurizing agents.

[0034] Specifically, 24-30% hydroxyethyl hexahydrotriazine, 12-15% 1,3,5-triacetyl hexahydrotriazine, and 12-15% 1,3,5-triazine-2,4-dione.

[0035] Based on the above weight percentages, the main component of the desulfurizing agent is ensured to be within a highly efficient reaction concentration range. At the same time, 24-30% hydroxyethyl hexahydrotriazine and 12-15% 1,3,5-triacetyl hexahydrotriazine ensure high desulfurization efficiency and reduce the risk of scaling. 12-15% 1,3,5-triazine-2,4-dione is also included. Too high a concentration will affect its solubility and desulfurization efficiency, while too low a concentration will reduce the thermal stability of the desulfurizing agent, making the main component prone to hydrolysis and affecting its high-temperature desulfurization performance.

[0036] Specifically, the pH control agent keeps the pH of the liquid desulfurizer at 8-10.

[0037] Specifically, the pH control agent is disodium hydrogen phosphate or sodium bicarbonate.

[0038] Using a pH control agent to stabilize the pH value at 8-10 can prevent excessively high pH values ​​from causing more scaling, and also prevent excessively low pH values ​​from causing triazine hydrolysis, thus ensuring that the desulfurizing agent has better process adaptability.

[0039] Specifically, the stabilizer is at least one of diethyl methylphosphonate and diethyl ethylphosphonate.

[0040] Diethyl methylphosphonate and diethyl ethylphosphonate have good chemical stability, which effectively prevents unnecessary chemical reactions from occurring during the storage and use of triazine desulfurizers, ensuring the stability of the desulfurization effect. At the same time, when diethyl methylphosphonate and diethyl ethylphosphonate are used in combination with triazine desulfurizers, a synergistic effect is produced. This synergistic effect stems from the complementarity of their chemical properties, making the desulfurization process more efficient and thorough.

[0041] Specifically, the scale inhibitor is at least one of sodium polymethacrylate and potassium polymethacrylate.

[0042] Sodium polymethacrylate and potassium polymethacrylate have a strong inhibitory effect on the formation of calcium and magnesium scale. When used in this invention, they mainly inhibit the scaling of calcium and magnesium ions, but have no synergistic effect on desulfurization.

[0043] Specifically, the bactericide is one of allylthiazole, sodium cresol, or sodium hypochlorite.

[0044] The selected bactericide has a synergistic effect with triazine. Under the combined effect, sulfate-reducing bacteria, iron bacteria, saprophytic bacteria and other bacteria are less likely to develop resistance to the desulfurizer. After adding the desulfurizer of the present invention, bacterial corrosion is less likely to occur in the desulfurization system, thus enhancing the process adaptability of the desulfurizer of the present invention.

[0045] On the other hand, the present invention also provides a method for preparing a liquid desulfurizing agent, the steps of which are as follows: weigh the above raw materials, mix and stir evenly to obtain a liquid desulfurizing agent.

[0046] Specifically, the steps are as follows:

[0047] S1. Deionized water, scale inhibitor and pH control agent are added to the reactor in sequence, mixed evenly and cooled to room temperature.

[0048] S2, 1,3,5-triazine-2,4-dione is slowly added to the above aqueous solution under stirring. After complete dissolution, hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine and sulfolane are added slowly in sequence, and stirring is continued until homogeneous.

[0049] S3, add stabilizer and bactericide to the above reaction vessel, mix and stir to obtain the liquid desulfurizer;

[0050] The stirring time in S1 is 10-30 min, followed by cooling for 2 h; the mixing time in S2 is 20-30 min; and the mixing time in S3 is 25-35 min.

[0051] Alkaline pH adjusters generate heat when dissolved in water, and at higher temperatures, triazine undergoes hydrolysis. The above method involves dissolving the pH adjuster first, allowing the solution to cool, and then adding the desulfurization agent to prevent hydrolysis of the agent and its impact on desulfurization efficiency. Adding sulfolane serves two purposes: firstly, it absorbs organic sulfur from the feed gas, reducing the total sulfur content in the natural gas; secondly, it absorbs CO2, reducing the impact of CO2 on triazine desulfurization. Furthermore, sulfolane itself has a strong ability to remove hydrogen sulfide.

[0052] The liquid desulfurizer prepared by this invention is a homogeneous and transparent solution with a pH of 8-10. The preparation method of this invention is simple and safe. The prepared liquid desulfurizer can produce no precipitates under conditions of high calcium, high magnesium concentrations, and high hydrogen sulfide content, and has good corrosion inhibition and bactericidal functions. Simultaneously, it maintains high hydrogen sulfide removal efficiency, exhibits rapid reaction speed, high selectivity, and stronger process adaptability.

[0053] Specifically, the liquid desulfurizer prepared by this invention can be used for pipeline injection and spray injection to remove hydrogen sulfide and organic sulfur.

[0054] In one possible implementation, a liquid desulfurizing agent is added to a sulfur-containing natural gas pipeline for desulfurization, at a hydrogen sulfide content of 300 mg / m³. 3 In an application scenario where the pipeline length is 1 km and the transport medium temperature is 30°C, the desulfurizing agent of this invention is added to the pipeline at a weight ratio of 10:1 to hydrogen sulfide. After adding the desulfurizing agent for 30 minutes, hydrogen sulfide in the natural gas is detected at the end of the pipeline. No hydrogen sulfide is detected, and the desulfurization rate has reached 100%.

[0055] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, materials and instruments, all of which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthetic methods.

[0056] Example 1

[0057] This embodiment provides a liquid desulfurizing agent and its preparation method. The weight percentages of each component in the obtained liquid desulfurizing agent are as follows:

[0058] Hydroxyethyl hexahydrotriazine 26%, 1,3,5-triacetyl hexahydrotriazine 12%, 1,3,5-triazine-2,4-dione 12%, sulfolane 5%, sodium bicarbonate 2%, diethyl methylphosphonate 10%, sodium polymethacrylate 5%, allylthiazole 1%, deionized water 27%.

[0059] The method for preparing the above-mentioned liquid desulfurizing agent is as follows: Deionized water, sodium polymethacrylate, and sodium bicarbonate are added sequentially to a reaction vessel, mixed evenly, and cooled to room temperature; 1,3,5-triazine-2,4-dione is slowly added to the above aqueous solution under stirring, and after complete dissolution, hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine, and sulfolane are added sequentially and stirred for 30 minutes; diethyl methylphosphonate and allylthiazole are added to the above reaction vessel and stirred for 30 minutes to obtain the liquid desulfurizing agent.

[0060] Example 2

[0061] This embodiment provides a liquid desulfurizing agent, and the weight percentage of each component of the obtained liquid desulfurizing agent is as follows:

[0062] Hydroxyethyl hexahydrotriazine 30%, 1,3,5-triacetyl hexahydrotriazine 15%, 1,3,5-triazine-2,4-dione 15%, sulfolane 8%, disodium hydrogen phosphate 5%, diethyl methylphosphonate 12%, sodium polymethacrylate 8%, allylthiazole 2%, deionized water 5%.

[0063] The above-mentioned liquid desulfurizer was prepared using the same method as in Example 1.

[0064] Example 3

[0065] This embodiment provides a liquid desulfurizing agent, and the weight percentage of each component of the obtained liquid desulfurizing agent is as follows:

[0066] Hydroxyethyl hexahydrotriazine 28%, 1,3,5-triacetyl hexahydrotriazine 13%, 1,3,5-triazine-2,4-dione 13%, sulfolane 6%, sodium bicarbonate 3%, diethyl methylphosphonate 10%, sodium polymethacrylate 6%, allylthiazole 2%, deionized water 19%.

[0067] The above-mentioned liquid desulfurizer was prepared using the same method as in Example 1.

[0068] Example 4

[0069] This embodiment provides a liquid desulfurizing agent and its preparation method. The weight percentages of the components of the obtained liquid desulfurizing agent are as follows: 28% hydroxyethyl hexahydrotriazine, 13% 1,3,5-triacetyl hexahydrotriazine, 13% 1,3,5-triazine-2,4-dione, 6% sulfolane, 3% sodium bicarbonate, 10% diethyl ethylphosphonate, 6% sodium polymethacrylate, 1% sodium cresol, and 20% deionized water.

[0070] The method for preparing the above-mentioned liquid desulfurizing agent is as follows: Deionized water, sodium polymethacrylate, and sodium bicarbonate are added to a reaction vessel in sequence, mixed evenly, and cooled to room temperature. Then, 1,3,5-triazine-2,4-dione is slowly added to the aqueous solution under stirring. After complete dissolution, hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine, and sulfolane are added in sequence and stirred for 25 minutes. Then, diethyl ethylphosphonate and sodium cresol are added to the reaction vessel and mixed and stirred for 30 minutes to obtain the liquid desulfurizing agent.

[0071] Comparative Example 1

[0072] The commercially available hydroxyethyl triazine desulfurizer THT was selected as the desulfurizer to be used.

[0073] Comparative Example 2

[0074] Imported triazine desulfurizer SC78 was selected as the desulfurizer used.

[0075] Comparative Example 3

[0076] This embodiment provides a liquid desulfurizing agent, and the weight percentage of each component of the obtained liquid desulfurizing agent is as follows:

[0077] 12% 1,3,5-Triacetylhexahydrotriazine, 12% 1,3,5-triazine-2,4-dione, 5% sulfolane, 2% sodium bicarbonate, 10% diethyl methylphosphonate, 5% sodium polymethacrylate, 1% allylthiazole, with the balance being deionized water.

[0078] The above-mentioned liquid desulfurizer was prepared using the same method as in Example 1.

[0079] Comparative Example 4

[0080] This embodiment provides a liquid desulfurizing agent, and the weight percentage of each component of the obtained liquid desulfurizing agent is as follows:

[0081] Hydroxyethyl hexahydrotriazine 26%, 1,3,5-triazine-2,4-dione 12%, sulfolane 5%, sodium bicarbonate 2%, diethyl methylphosphonate 10%, sodium polymethacrylate 5%, allylthiazole 1%, balance deionized water.

[0082] The above-mentioned liquid desulfurizer was prepared using the same method as in Example 1.

[0083] Comparative Example 5

[0084] This embodiment provides a liquid desulfurizing agent, and the weight percentage of each component of the obtained liquid desulfurizing agent is as follows:

[0085] Hydroxyethyl hexahydrotriazine 26%, 1,3,5-triacetyl hexahydrotriazine 12%, sulfolane 5%, sodium hydroxide 2%, diethyl methylphosphonate 10%, sodium polymethacrylate 5%, allylthiazole 1%, and the balance being deionized water.

[0086] The above-mentioned liquid desulfurizer was prepared using the same method as in Example 1.

[0087] Test case

[0088] 1. Sterilization performance evaluation experiment

[0089] Produced water from a gas field in Sichuan was used as a water sample. The corresponding culture medium was prepared according to the "Standard for Bacterial Analysis Methods of Injected Water in Oil and Gas Fields - Extinction Dilution Method" (SY / T 0532-2012). The number of sulfate-reducing bacteria in the water sample was determined to be 6.2 × 10⁻⁶ using the extinction dilution method. 4 CFU / mL, saprophytic bacteria 3.5 × 10⁻⁶ 3 Iron bacteria count / mL: 2.4 × 10⁶ cells / mL3 CFU / mL, total bacterial count 6.79 × 10⁻⁶ 4 per mL.

[0090] The liquid desulfurizing agents obtained in Examples 1-4, at a concentration of 300 mg / L, were injected into produced water samples at room temperature for bactericidal performance tests. The bacterial test results are shown in Table 1.

[0091] Table 1 Results of the bactericidal test

[0092]

[0093] Evaluation results show that when the concentration of the desulfurizing agent of this invention is 300 mg / L, bacteria in the produced water of the gas field are effectively controlled and almost completely killed. Comparative Examples 1 and 2, which did not contain any additional bactericides, showed lower bactericidal and bacteriostatic performance than the desulfurizing agent of this invention. Comparative Examples 3, 4, and 5, which all contained bactericides, exhibited similar bactericidal effects to the desulfurizing agent of this invention. Therefore, the desulfurizing agent provided by this invention has better bactericidal performance.

[0094] 2. Corrosion Inhibition Performance Evaluation Experiment

[0095] The liquid desulfurizing agent obtained in Examples 1-4, with a concentration of 500 mg / L, was used to conduct corrosion tests on L245N carbon steel samples under normal temperature and pressure. The test water was prepared water containing 30,000 mg / L sodium chloride and 1.5% CO2. 2 0.2% H2S, the results are shown in Table 2:

[0096] Table 2 Results of corrosion inhibition test

[0097]

[0098] Evaluation results show that the corrosion inhibition performance of the desulfurizer decreased after removing part of the main agent in the comparative example, especially after removing hydroxyethyl hexahydrotriazine, the corrosion inhibition performance of the desulfurizer decreased more significantly. In contrast, the present invention exhibits better corrosion inhibition performance compared to the comparative example. Therefore, the liquid desulfurizer provided by the present invention has better corrosion inhibition performance.

[0099] 3. Desulfurization rate evaluation experiment at 30℃

[0100] The liquid desulfurizing agents obtained in Examples 1-4 and Comparative Examples 1-5 were added to different reaction flasks, while no desulfurizing agent was injected into the blank flask. The static desulfurization efficiency of the desulfurizing agents was evaluated, and the steps are as follows:

[0101] (1) Accurately weigh 6.28g of sodium sulfide nonahydrate, dissolve it in distilled water and dilute it to 1000ml to prepare a sodium sulfide solution of 2.0g / L.

[0102] (2) Accurately measure 240 ml of 37% hydrochloric acid, dilute it with distilled water to 1000 mL, and prepare a 10% hydrochloric acid solution.

[0103] (3) Accurately weigh 100.00g of desulfurizing agent, dissolve it in distilled water and dilute it to 1000mL to prepare a desulfurizing agent solution of 100.0g / L.

[0104] (4) In a fume hood, add 3 mL of prepared 2.0 g / L sodium sulfide solution, 14 mL of distilled water, and 6 mL of prepared 100.0 g / L desulfurizing agent solution to the Erlenmeyer flask in sequence. Finally, add 3 mL of 10% hydrochloric acid solution. Immediately stopper the flask with a rubber stopper and shake it back and forth 100 times (to ensure that the gas and liquid in the flask are fully mixed). Let it stand in a 30°C water bath for 20 minutes. Connect the long glass tube inserted into the Erlenmeyer flask to a portable pump-type hydrogen sulfide detector through a silicone tube. At the same time, open the water stop clamps at both ends of the inlet and outlet. Measure the residual H2S concentration after adding the desulfurizing agent. Pump continuously for 30 seconds and read the highest value M on the detector.

[0105] (5) Perform a blank test according to the steps in (4), in which 6 mL of the prepared 100.0 g / L desulfurizing agent solution is replaced with 6 mL of distilled water, that is, the hydrogen sulfide concentration M1 is not obtained without the addition of desulfurizing agent.

[0106] (6) Desulfurization rate calculation:

[0107] S = ((M1-M) / M1) × 100%

[0108] In the formula:

[0109] M1┈┈H2S concentration measured without desulfurizing agent, mg / L

[0110] The H2S concentration measured after adding the desulfurizing agent (mg / L) is given.

[0111] S┈┈Desulfurization rate, %

[0112] Table 3. Results of sulfur removal efficiency test

[0113] Desulfurizer Desulfurization rate % Example 1 100 Example 2 99.2 Example 3 99.4 Example 4 98.5 Comparative Example 1 97.5 Comparative Example 2 98.7 Comparative Example 3 65.6 Comparative Example 4 55.4 Comparative Example 5 97.2

[0114] Evaluation results show that after removing 13% of hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine, and 1,3,5-triazine-2,4-dione from Comparative Examples 3, 4, and 5, respectively, the desulfurization efficiency of Comparative Examples 3 and 4 was significantly reduced, while the reduction in desulfurization rate of Comparative Example 5 was smaller. Comparative Examples 1 and 2, using only hydroxyethyl hexahydrotriazine as the desulfurizing agent, also achieved high desulfurization rates, but not as high as those of Examples 1-4. Compared to the comparative examples, the present invention can remove almost all the generated hydrogen sulfide, with a desulfurization rate approaching 100%. The liquid desulfurizing agent provided by the present invention has the same desulfurization efficiency as the commercially available hydroxyethyl hexahydrotriazine.

[0115] 4. Desulfurization rate evaluation experiment at 80℃

[0116] The evaluation method is the same as in Experiment 3, and the evaluation temperature is 80℃.

[0117] Table 4. Results of sulfur removal efficiency test

[0118] Desulfurizer Desulfurization rate % Example 1 98.8 Example 2 99.0 Example 3 98.9 Example 4 97.9 Comparative Example 1 64.6 Comparative Example 2 68.2 Comparative Example 3 58.2 Comparative Example 4 54.1 Comparative Example 5 37.2

[0119] Evaluation results show that the desulfurization rates of Comparative Examples 1, 2, and 5 decreased significantly at 80℃, while the desulfurization rates of Comparative Examples 3 and 4 were close to those measured at 30℃. In contrast, the desulfurization rates of Examples 1-4 showed relatively small changes. The liquid desulfurizer provided by this invention maintained a high desulfurization rate at 80℃, demonstrating good temperature resistance.

[0120] 5. Evaluation experiment on scale inhibition under high hydrogen sulfide content conditions

[0121] The scaling and scale inhibition performance of the liquid desulfurizing agents obtained in Examples 1-4 and the desulfurizing agents in Comparative Examples 1-5 under high hydrogen sulfide content conditions was evaluated, and the steps are as follows:

[0122] (1) At room temperature, add 300 mL of desulfurizing agent to a stoppered reaction flask.

[0123] (2) High-purity hydrogen sulfide gas is continuously pumped in through a gas distributor for 24 hours.

[0124] (3) After the experiment, observe whether there is any precipitate in the reaction bottle. After replacing the hydrogen sulfide with nitrogen, filter the solution with precipitate, dry it and weigh it to calculate the weight of the scale sample.

[0125] The experimental results are shown in Table 5:

[0126] Table 5. Results of scaling and scale inhibition tests conducted with high-purity hydrogen sulfide gas.

[0127]

[0128] The results of Comparative Examples 1 and 2 show that commercially available hydroxyethyl hexahydrotriazine desulfurizers react with hydrogen sulfide during the desulfurization process to produce precipitation. The results of Comparative Example 4 show that the addition of 1,3,5-triacetyl hexahydrotriazine can reduce the amount of precipitation. Compared to Comparative Examples 1, 2, and 4, the desulfurizer provided by this invention exhibits excellent scale-inhibiting properties under high-concentration hydrogen sulfide conditions, compared to commonly used hydroxyethyl hexahydrotriazine.

[0129] 6. Evaluation experiment on scale inhibition under high calcium chloride and high magnesium chloride concentration conditions

[0130] The descaling effects of the liquid desulfurizing agents obtained in Examples 1-4 and the desulfurizing agents in Comparative Examples 1-5 under conditions of high calcium chloride and high magnesium chloride concentrations were tested. The experimental steps are as follows:

[0131] (1) In a 500mL Erlenmeyer flask, prepare a total of 300mL of calcium chloride solution with a concentration of 2000mg / L and magnesium chloride solution with a concentration of 2000mg / L. Filter the solution using a glass frit funnel to remove insoluble impurities. Pour the filtered solution into a new 500mL Erlenmeyer flask.

[0132] (2) Add 30 mL of desulfurizing agent to the reaction flask;

[0133] (3) After shaking well, let stand for 4 hours, observe whether there is any precipitate in the reaction bottle, filter the solution with precipitate, dry it and weigh it, and calculate the weight of the scale sample.

[0134] The experimental results are shown in Table 6:

[0135] Table 6. Scaling test results under high calcium chloride and high magnesium chloride concentrations.

[0136]

[0137] Evaluation results show that, compared with the commonly used hydroxyethyltriazine in the market, the desulfurizer provided by this invention has excellent scale inhibition function in high concentration calcium chloride and magnesium chloride environments, as compared with comparative examples 1 and 2.

[0138] In summary, the desulfurizing agent of the present invention has the characteristics of high desulfurization rate, good corrosion inhibition and bactericidal properties, ability to inhibit scaling, and good high temperature resistance. It has strong process adaptability and can be used for pipeline injection and spray injection to remove hydrogen sulfide and organic sulfur.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid desulfurizing agent, characterized in that, By weight percentage: 36-66% triazine derivatives, 5-8% sulfolane, 2-5% pH control agent, 10-12% stabilizer, 5-8% scale inhibitor, 1-2% bactericide, and the balance being deionized water; Among them, the triazine derivatives are selected as a mixture of hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine and 1,3,5-triazine-2,4-dione.

2. The liquid desulfurizing agent according to claim 1, characterized in that, In the liquid desulfurizer, by weight percentage, there are 16-30% hydroxyethyl hexahydrotriazine, 10-18% 1,3,5-triacetyl hexahydrotriazine, and 10-18% 1,3,5-triazine-2,4-dione.

3. The liquid desulfurizing agent according to claim 2, characterized in that, Hydroxyethyl hexahydrotriazine 24-30%, 1,3,5-triacetyl hexahydrotriazine 12-15%, 1,3,5-triazine-2,4-dione 12-15%.

4. The liquid desulfurizing agent according to any one of claims 1-3, characterized in that, pH control agents maintain the pH value of the liquid desulfurizer at 8-10.

5. The liquid desulfurizing agent according to claim 4, characterized in that, The pH control agent is disodium hydrogen phosphate or sodium bicarbonate.

6. The liquid desulfurizing agent according to claim 5, characterized in that, The stabilizer is at least one of diethyl methylphosphonate and diethyl ethylphosphonate.

7. The liquid desulfurizing agent according to claim 6, characterized in that, The scale inhibitor is at least one of sodium polymethacrylate and potassium polymethacrylate.

8. The liquid desulfurizing agent according to claim 7, characterized in that, The bactericide is one of allylthiazole, sodium cresol, and sodium hypochlorite.

9. A method for preparing the liquid desulfurizing agent according to any one of claims 5-8, characterized in that, The steps are as follows: Weigh the above raw materials, mix and stir evenly to obtain liquid desulfurizer.

10. The method for preparing the liquid desulfurizing agent according to claim 9, characterized in that, The steps are as follows: S1. Deionized water, scale inhibitor and pH control agent are added to the reaction vessel in sequence, stirred evenly and cooled to room temperature. S2, 1,3,5-triazine-2,4-dione is slowly added to the above aqueous solution under stirring. After complete dissolution, hydroxyethyl hexahydrotriazine, 1,3,5-triacetyl hexahydrotriazine and sulfolane are added slowly in sequence, and stirring is continued until homogeneous. S3, add the stabilizer and bactericide to the above reaction vessel, mix and stir to obtain the liquid desulfurizer; The stirring time in S1 is 10-30 min, followed by cooling for 2 h; the mixing time in S2 is 20-30 min; and the mixing time in S3 is 25-35 min.

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