Complex iron desulfurizer for MDEA desulfurized analytical gas and its preparation method and use method

Abstract

The invention discloses a complex iron desulfurizer for MDEA desulfurization gas, comprising 15-20 parts of soluble iron salt, 25-30 parts of complexing agent, 1.6-3 parts of dispersant, 0.5-1.0 parts of promoter, 0.5-1.0 parts of sulfur modifier, 3-5 parts of stabilizer, 10-15 parts of alkali and water, and the iron ion concentration in the complex iron desulfurizer is required to reach 40000-45000ppm. The complex iron desulfurizer of the invention is suitable for removing high-content hydrogen sulfide in gas, and is particularly suitable for desulfurization treatment of MDEA desulfurization gas, which can solve the problems that the current desulfurizer cannot meet the desulfurization standard due to high hydrogen sulfide content in the desulfurization process of MDEA desulfurization gas, and is prone to slow regeneration speed and FeS precipitation.

Description

Technical Field

[0001] The invention relates to the technical field of desulfurizing agents, in particular to a complex iron desulfurizing agent suitable for desulfurizing MDEA desulfurized analytical gas, as well as the preparation and application of the complex iron desulfurizing agent. Background Art

[0002] As a green and clean energy, natural gas has attracted more and more attention for its development and utilization as global industrial development and energy demand increase, and has gradually become a necessity for sustainable development of energy and environment. Industrial development of natural gas must be purified, especially to remove sulfides in natural gas to reduce pollution from the source, so as to solve the problems of natural gas transportation, storage and harmless utilization.

[0003] The methyldiethanolamine (MDEA) method is currently widely used for natural gas desulfurization. It uses a 25% to 50% MDEA solution by mass to react with H2S in natural gas at an extremely fast rate to remove H2S. It is also called chemical absorption. The MDEA desulfurization process mainly includes absorption, flash evaporation, heat exchange and regeneration steps. The natural gas containing H2S, CO2 and other acidic components enters the bottom of the absorption tower after the liquid and solid impurities are removed through the inlet separator. It contacts with the MDEA solution from bottom to top in countercurrent to remove H2S, CO2, etc. The purified natural gas is removed from the tower after the MDEA droplets carried by it are removed through the outlet separator. The MDEA solution that absorbs H2S (usually called desulfurized rich liquid) flows out of the bottom of the absorption tower and passes through a flash tank to a certain pressure to separate the hydrocarbon impurities absorbed in the desulfurized rich liquid. The desulfurized rich liquid then passes through a filter. It enters the heat exchanger, is heated and then enters the regeneration tower operated at low pressure; in the regeneration tower, the desulfurized rich liquid flows from top to bottom and contacts with the gas (mainly water vapor) heated and vaporized in the reboiler, and the H2S and other substances in the solution are stripped out to obtain regenerated desulfurized lean liquid (the desulfurized lean liquid contains only a small amount of residual acid gas); the hot desulfurized lean liquid leaving the regeneration tower enters the heat exchanger, and the heat is recovered for heating the desulfurized rich liquid. The desulfurized lean liquid after heat exchange is cooled to an appropriate temperature by a cooler and sent to the absorption tower for recycling by a circulation pump.

[0004] The H2S, CO2 gas, acidic components and water vapor analyzed and stripped in the regeneration tower enter the cooler, and the acid gas and condensate are separated by condensation. The condensate is refluxed back to the top of the regeneration tower to recover the alcohol amine vapor brought out by the acid gas. The acid gas is the gas analyzed after the MDEA desulfurization regeneration, which is sent to the sulfur recovery device or other gas treatment facilities for further treatment, completely solving the H2S pollution problem.

[0005] The gas composition analyzed after the MDEA desulfurization regeneration is relatively simple, mainly H2S and CO2, wherein the hydrogen sulfide content is very high, usually reaching more than 40%. When the existing complex iron desulfurizer is used for treatment, FeS precipitation is easily generated due to the excessively high local hydrogen sulfide concentration (but the complex iron desulfurization process requires the generation of elemental sulfur rather than FeS), and is directly filtered out of the system with the desulfurization product elemental sulfur (commonly known as sulfur paste, sulfur), causing the iron ion content to drop rapidly and the desulfurization effect to deteriorate. When the iron ion content drops and the aeration volume remains unchanged, it is easy to cause overoxidation, further causing the consumption of reagents. In order to reduce FeS precipitation, although the ratio of iron ions to hydrogen sulfide can be increased by increasing the iron content concentration in the desulfurization liquid to reduce the generation of FeS, the dosage of the reagent will be increased and the investment cost will be increased, and the entrainment of the desulfurization liquid with the sulfur paste will also increase the reagent consumption. At the same time, the high iron ion concentration will also lead to the accelerated decomposition rate of the complexing agent, making the operating cost higher than the operation with the normal iron content concentration. Based on this situation, in view of the high hydrogen sulfide content in the desulfurized gas obtained by the MDEA method, a new complex iron desulfurizer needs to be developed for application in the field of desulfurization with high hydrogen sulfide content. Summary of the invention

[0006] In order to solve the problems that the current complex iron desulfurizer is difficult to meet the desulfurization requirements of high-content hydrogen sulfide, and is prone to slow regeneration and FeS precipitation, the present invention provides a complex iron desulfurizer that is particularly suitable for desulfurizing MDEA desulfurized analysis gas.

[0007] To achieve the above-mentioned purpose, the present invention provides a complex iron desulfurizer for MDEA desulfurization gas, which comprises the following raw material components by weight: 15-20 parts of soluble iron salt, 25-30 parts of complexing agent, 1.6-3 parts of dispersant, 0.5-1.0 parts of promoter, 0.5-1.0 parts of sulfur modifier, 3-5 parts of stabilizer, 10-15 parts of alkali and water, and the iron ion concentration in the complex iron desulfurizer is required to reach 40000-45000ppm;

[0008] Wherein, the complexing agent includes tetrasodium 3-hydroxy-2,2′-iminodisuccinate and sodium α-glucoheptonate;

[0009] The dispersant includes a combination of acrylic acid-maleic anhydride copolymer, p-toluenesulfonic acid and sodium styrenesulfonate;

[0010] The promoter is selected from at least one of a soluble copper salt, a soluble manganese salt, and a soluble cobalt salt;

[0011] The sulfur modifier is selected from at least one of polyacrylamide, polyether siloxane and fatty alcohol polyoxyethylene ether;

[0012] The stabilizer includes a combination of sorbitol, an antioxidant and a bactericide; the antioxidant includes an aromatic amine antioxidant and / or a hindered phenol antioxidant, wherein the aromatic amine antioxidant is selected from at least one of diphenylamine, diphenylamine derivatives, p-phenylenediamine, p-phenylenediamine derivatives, dihydroquinoline, and dihydroquinoline derivatives; the hindered phenol antioxidant is selected from at least one of antioxidant 2246, antioxidant 425, and antioxidant 330; the bactericide is selected from at least one of 1,2,3-triazine, 1,3,4-triazine, and 1,3,5-triazine.

[0013] The complex iron desulfurizer of the present invention, on the basis of utilizing complexing agent to play stable complexing action on the iron ion and ferrous ion of desulfurization main component, i.e., soluble iron salt, the uniform dispersion degree of desulfurization liquid is enhanced by the dispersant of specific combination with complexing agent, so as to significantly enhance the contact of iron ion with hydrogen sulfide and sulfur settling speed. In addition, in order to comprehensively improve desulfurization efficiency, not only the contact of iron ion with hydrogen sulfide is to be enhanced, the regeneration capacity of desulfurization rate and desulfurizer further needs to be improved, for this reason, the complex iron desulfurizer of the present invention, under the joint action of complexing agent and dispersant to soluble iron salt, further increases the co-catalyst to activate iron ion, reduces the ferric iron reaction barrier of desulfurization process, promotes its reaction with hydrogen sulfide ion (i.e., iron ion and hydrogen sulfide ion undergo redox reaction, iron ion is converted into ferrous ion, sulfide ion is converted into sulfur element), accelerates desulfurization speed, realizes rapid desulfurization. By the coordination of above-mentioned complexing agent, dispersant and co-catalyst, the high-efficiency desulfurization requirement of high hydrogen sulfide content gas can be met in the case of low desulfurizer holding amount.

[0014] In order to further maintain the stability, high-efficiency desulfurization effect and regeneration capacity of the desulfurizer in the recycling process and reduce the loss of the agent in the desulfurization process, a stabilizer and a sulfur modifier are also added to the complex iron desulfurizer of the present invention. Through the antioxidant effect of the stabilizer, the free radicals generated by the Fenton-like reaction between divalent iron and oxygen in the regeneration process of trivalent iron are captured, and the decomposition loss of the complexing agent caused by the destruction of organic matter such as the component complexing agent by the free radicals is avoided. The hydrophilic and hydrophobic groups of the sulfur modifier are evenly distributed between the suspended sulfur, the desulfurization liquid (referring to the desulfurization solution obtained by diluting the desulfurizer according to the iron ion concentration requirements used in the desulfurization process) and the bubbles, reducing the surface tension of the sulfur foam and reducing the coating of the sulfur foam; at the same time, the effects of the complexing agent and the dispersant are combined to accelerate the flocculation and sedimentation of the suspended sulfur, reduce the suspended sulfur in the desulfurization liquid, and increase the regeneration speed; and the flocculation and sedimentation of the suspended sulfur also leave space for the sedimentation of the newly generated sulfur foam, promoting the stable and continuous operation of the desulfurization system.

[0015] The complexing agent in the component is a mixture of tetrasodium 3-hydroxy-2,2'-iminodisuccinate and sodium α-glucoheptonic acid. The ability to complex iron and ferrous ions is not only significantly stronger than conventional complexing agents such as EDTA and NTA, but also can maintain high complexing ability and stability under strong alkaline conditions, and has the characteristics of environmental protection, non-toxicity and easy degradation. The dosage ratio of the complexing agent to the iron ion in the complex iron desulfurizer needs to be greater than 1:1, which can significantly increase the complexing ability for ferrous ions and effectively avoid the ferrous ions generated in the desulfurization process from being decomplexed to form ferrous sulfide or ferrous hydroxide due to insufficient complexing agent, thereby causing a large amount of reagent loss and a sharp decline in the desulfurization agent effect.

[0016] In the component, the dispersant uses acrylic acid-maleic anhydride copolymer to be compounded with p-toluenesulfonic acid and sodium styrenesulfonate, wherein the acrylic acid-maleic anhydride copolymer is conducive to the dispersion of complexed iron (i.e. the reaction product of the complexing agent and soluble iron salt) and sulfur particles, improves the uniformity of the effective ingredients in the desulfurization liquid and the aggregation speed of sulfur particles, but because the acrylic acid-maleic anhydride copolymer has viscosity, it will affect the separation effect of sulfur, and compounding with p-toluenesulfonic acid and sodium styrenesulfonate, the obtained mixed solution can produce synergistic results in terms of improving desulfurization efficiency, promoting sulfur sedimentation and reducing the foaming degree. In addition, because the α-glucoheptonic acid sodium selected by the complexing agent has a certain foaming property, the foaming degree of α-glucoheptonic acid sodium can be significantly offset by the dispersant, and the sulfur sedimentation speed is improved. And the acrylic acid-maleic anhydride copolymer can also control the carbonate content to be stable within a certain range, has obvious adaptability for the carbon dioxide in the MDEA analytical gas, will not affect the carbonate content due to the fluctuation of carbon dioxide in the MDEA analytical gas, and has a buffering effect on the pH value of the desulfurization liquid.

[0017] The stabilizer in the components includes triazine fungicides, which have strong inhibitory and killing power against various Gram-positive or Gram-negative bacteria, molds and yeasts. It can prevent the presence of excessive organic matter in the desulfurizer from providing a nutritional environment for microorganisms, leading to massive microbial reproduction and decomposition of various organic components in the desulfurizer, thereby ensuring the stable use of the desulfurizer and the long-term operation of the desulfurization system, reducing agent losses and reducing operating costs.

[0018] As a limitation of the above technical solution, the soluble iron salt is selected from at least one of iron sulfate, iron nitrate, and ammonium sulfate iron salt.

[0019] As a limitation of the above technical solution, the mass ratio of tetrasodium 3-hydroxy-2,2′-iminodisuccinate to sodium α-glucoheptonate in the complexing agent is (3-5):1.

[0020] As a limitation of the above technical solution, the mass ratio of acrylic acid-maleic anhydride copolymer, p-toluenesulfonic acid and sodium styrene sulfonate in the dispersant is 10:(1-2):(10-20).

[0021] As a limitation of the above technical solution, the mass ratio of the complexing agent to the dispersant in the complex iron desulfurizing agent is (9-15): 1

[0022] As a limitation of the above technical solution, the mass ratio of sorbitol, antioxidant and bactericide in the stabilizer is 10:(1-5):(1-3).

[0023] As a limitation of the above technical solution, the alkali is selected from at least one of sodium hydroxide solution, potassium hydroxide solution and ammonia water, wherein the sodium hydroxide solution and potassium hydroxide solution are generally selected with a mass concentration of 28-32%.

[0024] The main function of the alkali in the complex iron desulfurizer of this application is to adjust the pH value of the agent to facilitate the absorption of acidic H2S gas and enhance the reaction between complex iron and HS - However, the alkali should not be excessive, as excessive alkali will lead to precipitation of iron ions and reduce the effect.

[0025] The preferred proportions and preferred substances in each raw material component are further defined to improve and optimize the desulfurization effect of the complex iron desulfurizer of the present invention.

[0026] At the same time, the present invention provides a method for preparing the complex iron desulfurizer for desulfurized gas by the MDEA method as described above, comprising the following preparation steps:

[0027] The acrylic acid-maleic anhydride copolymer is dissolved in water, p-toluenesulfonic acid and sodium styrenesulfonate are added, the temperature is raised to 80-90°C, stirred for 3-5 hours and then cooled to 60-70°C, and then a soluble iron salt and a promoter are added. After they are completely dissolved, a complexing agent is added and dissolved until clear, and then the mixed solution is concentrated to obtain crystals, the crystals are collected by filtration, and water is added to dissolve, and finally a sulfur modifier, a stabilizer and an alkali are added, and the mixture is evenly mixed to obtain a red liquid complex iron desulfurizer.

[0028] The complex iron desulfurizer of the present invention can achieve a significant improvement in the desulfurization effect by simply mixing the various component raw materials. In order to further optimize the product and adapt to application requirements, the present invention also develops a specific preparation method to improve product performance, storage and transportation methods, and use effects.

[0029] In the preparation process of the complex iron desulfurizer, p-toluenesulfonic acid and sodium styrenesulfonate are used to react and modify the acrylic acid-maleic anhydride copolymer to form a mixture of different polymers to improve stability and functional diversity. After adding soluble iron salts, co-catalysts, and complexing agents, other impurities introduced into the desulfurizer during the preparation and feeding process are reduced through concentration and crystallization, which plays a purification role and optimizes product performance.

[0030] As a limitation of the above technical solution, the mixed solution is concentrated by reduced pressure evaporation at a pressure of -80 to -85 kPa and a temperature of 60 to 70° C. The concentration process makes the volume of the remaining solution reach 13 to 17% of the volume of the original solution.

[0031] In addition, the present invention also provides a method for using the complex iron desulfurizer for MDEA desulfurized analytical gas as described above, which is to contact the complex iron desulfurizer with the MDEA desulfurized analytical gas to react with H2S in the analytical gas to produce elemental S; and / or,

[0032] The H2S content in the MDEA desulfurized gas to be treated is not less than 40%, and the desulfurized gas flow rate in the desulfurization tower is 400-500m 3 / h, desulfurization tower lean liquid circulation volume 150~200m 3 / h, under the desulfurization conditions of iron ion concentration of 800-1000ppm, the hydrogen sulfide content in the desulfurized gas is less than 20mg / m 3 .

[0033] In summary, the complex iron desulfurizer of the present invention utilizes the compound of complexing agent, dispersant and co-catalyst in the components, and at the same time improves the desulfurization amount, desulfurization speed and sulfur sedimentation speed of hydrogen sulfide, so as to achieve the high efficiency desulfurization requirements of high hydrogen sulfide content gas under the condition of low desulfurizer holding amount; and further coordinates stabilizer and sulfur modifier to keep the desulfurizer stable and efficient desulfurization and regeneration ability during the recycling process, and promotes the stable and continuous operation of the desulfurization system. Using the desulfurizer of the present invention, not only the desulfurization efficiency is high and the desulfurization operation is stable, but also the consumption of reagents can be significantly reduced, the operating cost is saved, and the quality of sulfur paste is greatly improved, and the value of by-products in the desulfurization process is improved. The complex iron desulfurizer of the present invention can also further improve the product performance and use effect through a specific preparation method, and improve the system operation value on the basis of meeting the hydrogen sulfide emission standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 , a photo of the initial stage of concentration of the complex iron desulfurizer of Example 4 during the preparation process;

[0035] Figure 2 , sample photos of the complex iron desulfurizer obtained in Example 4;

[0036] Figure 3 , pH value measurement photo of the complex iron desulfurizer obtained in Example 4;

[0037] Figure 4 , a photo of the mass measurement of a 50 mL sample of the complex iron desulfurizer obtained in Example 4;

[0038] Figure 5 , Photographs showing the absorbance measurement of the iron ion content in the complex iron desulfurizer obtained in Example 4;

[0039] Figure 6 , the standard curve of absorbance and ferrous mass used to calculate the iron ion concentration in the complex iron desulfurizer. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The chemical raw materials involved in the following examples are all typical products purchased from the market.

[0042] Example

[0043] The following examples relate to the complex iron desulfurizing agent of the present invention and its preparation.

[0044] Example 1

[0045] A complex iron desulfurizer comprises the following raw material components:

[0046] 21.3kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 6.2kg of sodium α-glucoheptonic acid, 0.8kg of acrylic acid-maleic anhydride copolymer, 0.1kg of p-toluenesulfonic acid, 1.0kg of sodium styrene sulfonate, 16kg of ferrous sulfate, 0.9kg of manganese chloride, 0.85kg of polyether siloxane, 2.8kg of sorbitol, 1.2kg of antioxidant 2246, 0.4kg of 1,3,5-triazine, 13.5kg of sodium hydroxide solution (mass concentration 30%), and 40kg of water.

[0047] The preparation process is as follows: according to the ratio of raw material dosage, acrylic acid-maleic anhydride copolymer is first dissolved in water, and then p-toluenesulfonic acid, sodium styrene sulfonate, ferric sulfate, and manganese chloride are added in sequence, stirred to dissolve, and then 3-hydroxy-2,2′-iminodisuccinic acid tetrasodium and α-glucoheptonic acid sodium are added. After complete dissolution, polyether siloxane, sorbitol, antioxidant 2246, and 1,3,5-triazine are added in sequence, and finally sodium hydroxide solution is added and mixed evenly to obtain 105.05 kg of complex iron desulfurizer.

[0048] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 10.27 and a density of 1.29 g / cm 3 , iron ion concentration 42346ppm.

[0049] Example 2

[0050] The complex iron desulfurizer of this embodiment has the same raw material components as those of Example 1, except that the desulfurizer is prepared. The specific preparation steps are as follows:

[0051] The acrylic acid-maleic anhydride copolymer is first dissolved in 100 kg of water (the 100 kg of water used here is not included in the raw material components of the desulfurizer), p-toluenesulfonic acid and sodium styrenesulfonate are added, the temperature is raised to 80°C, stirred for 4 hours, cooled to 60°C, ferric sulfate and manganese chloride are added, and after complete dissolution, 3-hydroxy-2,2'-iminodisuccinic acid tetrasodium and α-glucoheptonic acid sodium are added in sequence, and then concentrated under a pressure of -85 kPa and 60°C. The remaining liquid is concentrated to 14% of the volume of the original solution and then filtered, and the wet solid is dissolved in water (the water used here is the water amount in the formula), and finally polyether siloxane, sorbitol, antioxidant 2246, 1,3,5-triazine and sodium hydroxide solution are added and mixed evenly to obtain 92.14 kg of complex iron desulfurizer.

[0052] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 10.42 and a density of 1.18 g / cm 3 , iron ion concentration 41127ppm.

[0053] Embodiment 3:

[0054] A complex iron desulfurizer comprises the following raw material components:

[0055] 21kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 5kg of sodium α-glucoheptonic acid, 0.9kg of acrylic acid-maleic anhydride copolymer, 0.16kg of p-toluenesulfonic acid, 1.64kg of sodium styrene sulfonate, 3kg of ferric sulfate, 14.5kg of ferric nitrate, 0.6kg of cobalt chloride, 0.6kg of polyacrylamide, 2.4kg of sorbitol, 0.5kg of antioxidant 3300, 0.6kg of 1,2,3-triazine, 11kg of potassium hydroxide solution (mass concentration 30%), and 30kg of water.

[0056] The preparation method of the above catalyst comprises at least the following steps:

[0057] The acrylic acid-maleic anhydride copolymer is dissolved in water (100 kg of water is used here, which is not included in the desulfurizer component), p-toluenesulfonic acid and sodium styrenesulfonate are added, the temperature is raised to 85°C, stirred for 3.5 hours, cooled to 70°C, ferric sulfate, ferric nitrate and cobalt chloride are added, and after complete dissolution, 3-hydroxy-2,2′-iminodisuccinic acid tetrasodium and α-glucoheptonic acid sodium are added in sequence, and then the residual liquid is concentrated to 15% of the volume of the original solution under -80 kPa pressure and 70°C, and then filtered, the wet solid is dissolved in water (the water used here is the water amount in the formula), and finally polyacrylamide, sorbitol, antioxidant 330, 1,2,3-triazine and potassium hydroxide solution are added and mixed evenly to obtain 82.33 kg of complex iron desulfurizer.

[0058] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 9.87 and a density of 1.21 g / cm 3 , iron ion concentration 42802ppm.

[0059] Example 4

[0060] A complex iron desulfurizer comprises the following raw material components:

[0061] 24kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 5kg of sodium α-glucoheptonic acid, 0.8kg of acrylic acid-maleic anhydride copolymer, 0.12kg of p-toluenesulfonic acid, 1.28kg of sodium styrene sulfonate, 10kg of ammonium ferric sulfate, 5kg of ferric nitrate, 4kg of ferric sulfate, 0.2kg of copper nitrate, 0.3kg of manganese sulfate, 0.4kg of cobalt chloride, 0.2kg of fatty alcohol polyoxyethylene ether, 0.15kg of polyacrylamide, 0.4kg of polyether siloxane, 2.6kg of sorbitol, 0.8kg of antioxidant 425, 0.5kg of 1,3,4-triazine, 12.5kg of ammonia water (mass concentration 20%), and 30kg of water.

[0062] The preparation method of the above catalyst comprises at least the following steps:

[0063] The acrylic acid-maleic anhydride copolymer was dissolved in water (100 kg of water was used here, which was not included in the desulfurizer component), p-toluenesulfonic acid and sodium styrenesulfonate were added, the temperature was raised to 90°C, stirred for 4.5 hours, and the temperature was lowered to 68°C, and ferric sulfate, ferric nitrate, ammonium ferric sulfate, copper nitrate, manganese sulfate, and cobalt chloride were added. After they were completely dissolved, tetrasodium 3-hydroxy-2,2′-iminodisuccinate and sodium α-glucoheptonic acid were added in sequence, and then concentrated under a pressure of -82 kPa and 68°C. The initial photo of the concentration is shown in the attached figure. Figure 1, the remaining liquid is concentrated to 14% of the volume of the original solution and then filtered (most of the impurity salts are in the solution, and most of the main components of the complex iron are precipitated) to obtain a wet solid (crystals containing about 20-30% water). Water (the water used here is the amount of water in the formula) is added to dissolve it, and finally fatty alcohol polyoxyethylene ether, polyacrylamide, polyether siloxane, sorbitol, antioxidant 425, 1,3,4-triazine and ammonia water are added and mixed evenly to obtain 87.73 kg of complex iron desulfurizer.

[0064] The obtained complex iron desulfurizer is a wine red transparent liquid, see the attached figure Figure 2 ; The pH of the complex iron desulfurizer was determined to be 9.99 and the density was 1.20 g / cm 3 , pH measurement photos and 50mL sample mass determination photos are shown in the attached figures Figure 3 , 4 The iron ion concentration in the complex iron desulfurizer was determined by o-phenanthroline colorimetry to be 42172ppm (50606.57mg / L), and the absorbance result of the iron ion content is shown in the attached photo. Figure 5 (Phenanthroline colorimetry is used, wavelength is 510nm, desulfurizer is diluted 250 times, phenanthroline only reacts with ferrous ions, when measuring trivalent iron, a reducing agent is added to convert it into ferrous iron for measurement, the masses of iron in the two valence states are the same, so the calculation results are the same), the standard curve of absorbance and ferrous iron mass used for calculation is shown in the attached figure Figure 6 .

[0065] Comparative Example

[0066] The following comparative examples involve the comparison of different complex iron desulfurizers with the complex iron desulfurizer of the present invention.

[0067] Comparative Example 1

[0068] This comparative example is a complex iron desulfurization liquid with excellent desulfurization effect used in the industry, and its specific composition is as follows:

[0069] 100 kg of aspartic acid, 63 kg of maleic anhydride, 55 kg of iron powder, 0.61 kg of chromium chloride and 180 kg of water are added to a reactor, stirred evenly, and then heated to 100° C. 15 kg of 20% ammonia water and 400 kg of saturated ammonium chloride aqueous solution are mixed evenly and then slowly added to the reactor for 5 hours. After the addition, the temperature is raised to 135° C., and the reaction is kept warm for 2 hours. Nitrogen is passed through for 10 minutes, and the mixture is filtered. 0.9 kg of sodium molybdate and 1.7 kg of polyethylene glycol are added to the obtained filtrate, and the temperature is raised to 60° C. and air is bubbled for 35 minutes. The mixture is concentrated until the feed liquid becomes viscous, filtered, dried and crushed to obtain a polyaspartic acid complex iron desulfurizer.

[0070] The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was detected by high performance liquid chromatography and was less than 1%. The iron ion content in the polyaspartic acid complex iron was detected by spectrophotometry and was 28.70%.

[0071] Comparative Example 2

[0072] The complex iron desulfurizer of this comparative example is different from the raw material components of the present invention (specifically comparative example 4) in that no sulfur modifier and stabilizer are used to reflect the influence of the sulfur modifier and stabilizer on the desulfurization performance.

[0073] A complex iron desulfurizer comprises the following raw material components:

[0074] 24kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 5kg of sodium α-glucoheptonic acid, 0.8kg of acrylic acid-maleic anhydride copolymer, 0.12kg of p-toluenesulfonic acid, 1.28kg of sodium styrenesulfonate, 10kg of ammonium ferric sulfate, 5kg of ferric nitrate, 4kg of ferric sulfate, 0.2kg of copper nitrate, 0.3kg of manganese sulfate, 0.4kg of cobalt chloride, 12.5kg of ammonia water (mass concentration 20%), and 34.65kg of water.

[0075] The preparation method of the above catalyst comprises at least the following steps:

[0076] The acrylic acid-maleic anhydride copolymer is dissolved in water (100 kg of water is used here, which is not included in the desulfurizer component), p-toluenesulfonic acid and sodium styrenesulfonate are added, the temperature is raised to 90°C, stirred for 4.5 hours, cooled to 68°C, ferric sulfate, ferric nitrate, ammonium ferric sulfate, copper nitrate, manganese sulfate, and cobalt chloride are added, and after complete dissolution, 3-hydroxy-2,2′-iminodisuccinic acid tetrasodium and α-glucoheptonic acid sodium are added in sequence, and then concentrated to 14% of the original solution volume under -82 kPa pressure and 68°C conditions, and then filtered, the wet solid is dissolved in water (the water used here is the water amount in the formula), and finally ammonia water is added and mixed evenly to obtain 87.70 kg of complex iron desulfurizer.

[0077] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 10.08 and a density of 1.17 g / cm 3 , iron ion concentration 42159ppm.

[0078] Comparative Example 3

[0079] The complex iron desulfurizer of this comparative example is different from the raw material components of the present invention (specifically comparative example 4) in the selection of the dispersant to reflect the influence of the dispersant on the desulfurization performance.

[0080] Comparative Example 3-1

[0081] A complex iron desulfurizer comprises the following raw material components:

[0082] 24kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 5kg of sodium α-glucoheptonic acid, 2.2kg of sodium styrene sulfonate, 10kg of ammonium ferric sulfate, 5kg of ferric nitrate, 4kg of ferric sulfate, 0.2kg of copper nitrate, 0.3kg of manganese sulfate, 0.4kg of cobalt chloride, 0.2kg of fatty alcohol polyoxyethylene ether, 0.15kg of polyacrylamide, 0.4kg of polyether siloxane, 2.6kg of sorbitol, 0.8kg of antioxidant 425, 0.5kg of 1,3,4-triazine, 12.5kg of ammonia water (mass concentration 20%), and 30kg of water.

[0083] The preparation method of the above catalyst comprises at least the following steps:

[0084] Sodium styrene sulfonate is dissolved in water (100 kg of water is used here, which is not included in the desulfurizer component), heated to 90°C, stirred for 4.5 hours, cooled to 68°C, and ferric sulfate, ferric nitrate, ammonium ferric sulfate, copper nitrate, manganese sulfate, and cobalt chloride are added. After complete dissolution, tetrasodium 3-hydroxy-2,2′-iminodisuccinate and sodium α-glucoheptonic acid are added in sequence. Then, the solution is concentrated to 14% of the original solution volume at a pressure of -82 kPa and 68°C, and then filtered. The wet solid is dissolved in water (the water used here is the amount of water in the formula), and finally, fatty alcohol polyoxyethylene ether, polyacrylamide, polyether siloxane, sorbitol, antioxidant 425, 1,3,4-triazine and ammonia water are added and mixed evenly to obtain 87.75 kg of complex iron desulfurizer.

[0085] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 10.16 and a density of 1.20 g / cm 3 , iron ion concentration 42188ppm.

[0086] Comparative Example 3-2

[0087] A complex iron desulfurizer comprises the following raw material components:

[0088] 24kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 5kg of sodium α-glucoheptonic acid, 2.2kg of sodium pyrophosphate, 10kg of ammonium ferric sulfate, 5kg of ferric nitrate, 4kg of ferric sulfate, 0.2kg of copper nitrate, 0.3kg of manganese sulfate, 0.4kg of cobalt chloride, 0.2kg of fatty alcohol polyoxyethylene ether, 0.15kg of polyacrylamide, 0.4kg of polyether siloxane, 2.6kg of sorbitol, 0.8kg of antioxidant 425, 0.5kg of 1,3,4-triazine, 12.5kg of ammonia water (mass concentration 20%), and 30kg of water.

[0089] The preparation method of the above catalyst comprises at least the following steps:

[0090] Sodium pyrophosphate was dissolved in water (100 kg of water was used here, which was not included in the desulfurizer component), heated to 90°C, stirred for 4.5 hours, cooled to 68°C, and ferric sulfate, ferric nitrate, ammonium ferric sulfate, copper nitrate, manganese sulfate, and cobalt chloride were added. After complete dissolution, tetrasodium 3-hydroxy-2,2′-iminodisuccinate and sodium α-glucoheptonic acid were added in sequence. Then, the solution was concentrated to 14% of the original solution volume at a pressure of -82 kPa and 68°C, and then filtered. The wet solid was dissolved in water (the water used here is the amount of water in the formula), and finally, fatty alcohol polyoxyethylene ether, polyacrylamide, polyether siloxane, sorbitol, antioxidant 425, 1,3,4-triazine and ammonia water were added and mixed evenly to obtain 87.71 kg of complex iron desulfurizer.

[0091] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 10.14 and a density of 1.20 g / cm 3 , iron ion concentration 42151ppm.

[0092] Comparative Example 4

[0093] The complex iron desulfurizer of this comparative example is different from the raw material components of the present invention (specifically comparative example 4) in the selection of the sulfur modifier and the stabilizer to reflect the influence of the sulfur modifier and the stabilizer on the desulfurization performance.

[0094] A complex iron desulfurizer comprises the following raw material components:

[0095] 24kg of tetrasodium 3-hydroxy-2,2′-iminodisuccinate, 5kg of sodium α-glucoheptonic acid, 0.8kg of acrylic acid-maleic anhydride copolymer, 0.12kg of p-toluenesulfonic acid, 1.28kg of sodium styrene sulfonate, 10kg of ammonium ferric sulfate, 5kg of ferric nitrate, 4kg of ferric sulfate, 0.2kg of copper nitrate, 0.3kg of manganese sulfate, 0.4kg of cobalt chloride, 0.75kg of polyethylene glycol ether, 2.6kg of maltose, 0.8kg of sodium dodecyl sulfonate, 0.5kg of 1,3,4-triazine, 12.5kg of ammonia water (mass concentration 20%), and 30kg of water.

[0096] The preparation method of the above catalyst comprises at least the following steps:

[0097] The acrylic acid-maleic anhydride copolymer is dissolved in water (100 kg of water is used here, which is not included in the desulfurizer component), p-toluenesulfonic acid and sodium styrenesulfonate are added, the temperature is raised to 90°C, stirred for 4.5 hours, cooled to 68°C, ferric sulfate, ferric nitrate, ammonium ferric sulfate, copper nitrate, manganese sulfate, and cobalt chloride are added, and after complete dissolution, 3-hydroxy-2,2'-iminodisuccinic acid tetrasodium and sodium α-glucoheptonic acid are added in sequence, and then concentrated to 14% of the original solution volume under -82 kPa pressure and 68°C, and then filtered, the wet solid is dissolved in water (the water used here is the water amount in the formula), and finally polyethylene glycol ether, maltose, sodium dodecyl sulfate, 1,3,4-triazine and ammonia water are added and mixed evenly to obtain 87.73 kg of complex iron desulfurizer.

[0098] The obtained complex iron desulfurizer is a wine red transparent liquid with a pH of 10.12 and a density of 1.20 g / cm 3 , iron ion concentration 42204ppm.

[0099] Effect verification:

[0100] The hydrogen sulfide gas source is the desulfurized gas obtained by desulfurizing and regenerating natural gas by MDEA method (hereinafter referred to as natural gas desulfurized desulfurized gas), in which the H2S content is 51.25% (777.902g / m 3 ), add a branch pipe from the atmospheric pressure analytical gas pipeline to lead out a stream of analytical gas for the experiment.

[0101] In the filtrate tank, each complex iron desulfurizer prepared in the embodiment and the comparative example was added into water to prepare 60L desulfurization liquid with an iron ion concentration of 800ppm, and the pH was adjusted to 9.0. The desulfurized analytical gas of the natural gas was introduced into the desulfurization tower from the bottom at a rate of 400L / h, and the adjusted desulfurization liquid was sprayed into the desulfurization tower from the top of the desulfurization tower. The feeding rate of the desulfurization liquid was controlled to be 150L / h, and the temperature of the desulfurization liquid was controlled to be 28-32°C. When the desulfurization liquid was emptied (empty, that is, all the adjusted desulfurization liquid was pumped into the desulfurization tower through the pump, the liquid level of the filtrate tank was 0, that is, the liquid level of the tank storing the desulfurization liquid was about to reach the lowest, and if the pump continued to run, it would trip due to idling without material), the analytical gas was stopped, and the hydrogen sulfide content in the purified gas one second before the desulfurization liquid was emptied was recorded. The desulfurized rich liquid (desulfurized rich liquid refers to the liquid after the reaction of desulfurized liquid and H2S, and the rich liquid basically cannot continue to absorb H2S) is pumped into the regeneration tower from the bottom of the tower through the rich liquid pump, and regenerated by air aeration. The air flow rate is 2m 3 / h, the temperature of the regeneration tower is controlled at 50-55°C by steam, and the desulfurized lean liquid is obtained after regeneration for 15 minutes (the desulfurized lean liquid refers to the newly prepared desulfurized liquid in the filtrate tank or the desulfurized liquid after regeneration and aeration in the regeneration tower. The desulfurized lean liquid has the ability to remove H2S). The desulfurized lean liquid is pumped into the plate and frame filter through the lean liquid pump for filtration to obtain a sulfur filter cake (referred to as sulfur paste). The weight of the sulfur paste is recorded, and the filter cake is sampled to detect the sulfur content, and the sulfur yield is converted (the sulfur content detection method is GB / T2449.1-2021).

[0102] Desulfurization and regeneration 10 times operation process: Add several complex iron desulfurizers to water in the filtrate tank to prepare 60L desulfurization liquid with an iron ion concentration of 800ppm, adjust the pH to 9.0, and pass the desulfurized and analyzed gas of natural gas from the bottom to the desulfurization tower at a rate of 400L / h. Spray the adjusted desulfurized liquid into the desulfurization tower from the top of the desulfurization tower, control the desulfurization liquid feed rate to 150L / h, and control the temperature of the desulfurization liquid at 28-32°C. Stop passing the analysis gas when the desulfurization solution is emptied, and record the hydrogen sulfide content in the purified gas one second before the desulfurization liquid is emptied. Pump all the desulfurized rich liquid from the bottom of the tower into the regeneration tower through the rich liquid pump, and regenerate by air aeration. The air flow rate is 2m 3 / h, the temperature of the regeneration tower is controlled at 50-55℃ by steam, regeneration is carried out for 30 minutes, the regenerated desulfurized lean liquid is pumped into the plate-frame filter through the lean liquid pump for filtration to obtain sulfur paste, and the filtrate is pumped into the filtrate tank for storage. The filtrate is pumped into the desulfurization tower again, and the air is desulfurized at the same time, and the above desulfurization and regeneration operations are repeated 9 times each before stopping desulfurization (a total of 10 desulfurization operations, 10 regeneration and sulfur separation operations).

[0103] The comparison results of desulfurization effects of various desulfurizers are shown in the following table:

[0104]

[0105] From the results in the above table, it can be seen that when the existing complex iron desulfurizer is used to treat the desulfurized gas with high hydrogen sulfide content, the H2S content increases significantly after desulfurization, and far exceeds the national standard requirement of 20mg / m 3 , which increases the corrosion of subsequent processing equipment and significantly increases the danger of the desulfurization section. However, the use of the complex iron desulfurizer of the present invention improves the desulfurization efficiency, greatly reduces the H2S content after desulfurization, and the reduction rate exceeds 99%, and the iron ion loss rate is reduced by more than 90%, which reduces the loss of the desulfurizer, thereby reducing the operating cost of the desulfurization system, the pH value of the desulfurization process is more stable, and the consumption of alkali sources is also reduced.

[0106] According to the above results, it can be seen that in the raw material composition of the complex iron desulfurizer of the present invention, the specific dispersant increases the sulfur sedimentation rate by more than 5%, which can effectively shorten the regeneration time in actual production, thereby improving the desulfurization efficiency, making the sulfur sedimentation rate faster, and at the same time alleviating the pH value drop rate, which is particularly suitable for treating natural gas desulfurization and analysis gas containing high concentrations of hydrogen sulfide. For other dispersants, the hydrogen sulfide content increases by more than 10 times after desulfurization, and the sulfur sedimentation rate, pH value drop rate, etc. are reduced by about 5%.

[0107] In summary, the complex iron desulfurizer of the present invention can solve the technical problem that the current complex iron desulfurizer is difficult to meet the desulfurization requirements of gases with high hydrogen sulfide content, and is particularly suitable for the desulfurization treatment of MDEA desulfurized analytical gas. It can effectively avoid the problems of slow regeneration speed and FeS precipitation that are prone to occur in the desulfurization process of MDEA desulfurized analytical gas, making the desulfurization of MDEA desulfurized analytical gas more efficient, safer and more valuable.

Claims

1. A complex iron desulfurizer for MDEA desulfurized gas, characterized in that: The invention comprises the following raw material components in parts by weight: 15-20 parts of soluble iron salt, 25-30 parts of complexing agent, 1.6-3 parts of dispersant, 0.5-1.0 parts of promoter, 0.5-1.0 parts of sulfur modifier, 3-5 parts of stabilizer, 10-15 parts of alkali and water. The iron ion concentration in the complex iron desulfurizer is required to reach 40000-45000ppm; Wherein, the complexing agent includes tetrasodium 3-hydroxy-2,2′-iminodisuccinate and sodium α-glucoheptonate; The dispersant includes a combination of acrylic acid-maleic anhydride copolymer, p-toluenesulfonic acid and sodium styrenesulfonate; The mass ratio of acrylic acid-maleic anhydride copolymer, p-toluenesulfonic acid and sodium styrene sulfonate in the dispersant is 10: (1-2): (10-20); The mass ratio of complexing agent to dispersant is (9-15):1; The promoter is selected from at least one of a soluble copper salt, a soluble manganese salt, and a soluble cobalt salt; The sulfur modifier is selected from at least one of polyacrylamide, polyether siloxane and fatty alcohol polyoxyethylene ether; The stabilizer includes a combination of sorbitol, an antioxidant and a bactericide; the antioxidant includes an aromatic amine antioxidant and / or a hindered phenol antioxidant, wherein the aromatic amine antioxidant is selected from at least one of diphenylamine, diphenylamine derivatives, p-phenylenediamine, p-phenylenediamine derivatives, dihydroquinoline, and dihydroquinoline derivatives; the hindered phenol antioxidant is selected from at least one of antioxidant 2246, antioxidant 425, and antioxidant 330; the bactericide is selected from at least one of 1,2,3-triazine, 1,3,4-triazine, and 1,3,5-triazine.

2. The chelated iron desulfurizer for desulfurized gas by MDEA method according to claim 1, characterized in that: The soluble iron salt is selected from at least one of iron sulfate, iron nitrate, and ammonium sulfate iron salt.

3. The complex iron desulfurizer for desulfurized gas by MDEA method according to claim 1, characterized in that: The mass ratio of tetrasodium 3-hydroxy-2,2′-iminodisuccinate to sodium α-glucoheptonic acid in the complexing agent is (3-5):

1.

4. The complex iron desulfurizer for desulfurized gas by MDEA method according to claim 1, characterized in that: The mass ratio of sorbitol, antioxidant and bactericide in the stabilizer is 10:(1-5):(1-3).

5. The complex iron desulfurizer for desulfurized gas by MDEA method according to claim 1, characterized in that: The alkali is selected from at least one of sodium hydroxide solution, potassium hydroxide solution and ammonia water.

6. A method for preparing a complex iron desulfurizer for MDEA desulfurized gas as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following preparation steps: Dissolve acrylic acid-maleic anhydride copolymer in water, add p-toluenesulfonic acid and sodium styrenesulfonate, heat to 80-90°C, stir for 3-5 hours and then cool to 60-70°C, then add soluble iron salt and promoter, add complexing agent after complete dissolution and dissolve until clear, then concentrate the mixed solution to obtain crystals, collect the crystals by filtration, add water to dissolve, finally add sulfur modifier, stabilizer and alkali, mix well to obtain red liquid complex iron desulfurizer.

7. The method for preparing the complex iron desulfurizer for MDEA desulfurized gas according to claim 6, characterized in that: The concentration treatment adopts reduced pressure evaporation concentration, the pressure is -80~-85kPa, the temperature is 60~70℃, and the concentration makes the residual solution volume reach 13~17% of the original solution volume.

8. A method for using the complex iron desulfurizer for desulfurized gas by MDEA as claimed in any one of claims 1 to 5, characterized in that: The complex iron desulfurizer is contacted with the MDEA desulfurized analytical gas to react with H2S in the analytical gas to produce elemental S; and / or, The H2S content in the MDEA desulfurized gas to be treated is not less than 40%, and the desulfurized gas flow rate in the desulfurization tower is 400~500m 3 / h, desulfurization tower lean liquid circulation volume 150~200m 3 / h, under the desulfurization conditions of iron ion concentration of 800~1000ppm, the hydrogen sulfide content in the desulfurized gas is less than 20mg / m 3 .

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