A kind of acid gas complex iron desulfurization process

Abstract

The present invention relates to the field of desulfurization technology, and proposes an acid gas complex iron desulfurization process, which includes the following steps: S1, after the hydrogen sulfide-containing gas is pressurized, it contacts with the desulfurizer from bottom to top in the desulfurization tower in reverse direction for desulfurization, and then is discharged from the top of the desulfurization tower; S2, after the desulfurization, the solution at the bottom of the desulfurization tower is oxidized in an oxidation regeneration tower, and then centrifuged to obtain sulfur; the desulfurizer includes the following raw materials in parts by weight: 15-20 parts of soluble iron salt, 50-60 parts of complexing agent, 0.8-1 part of corrosion inhibitor, 20-30 parts of alkaline substance, 0.5-1 part of sulfur precipitant, and 90-110 parts of water; the complexing agent is a carboxyl-containing compound; the sulfur precipitant is composed of sodium polystyrene sulfonate, lignin sulfonate, and polyoxyethylene ether. Through the above technical scheme, the problems of low sulfur capacity and high degradation rate of complex iron desulfurizer in the related technology are solved.

Description

Technical Field

[0001] The invention relates to the technical field of desulfurization, and in particular to an acid gas complex iron desulfurization process. Background Art

[0002] The complex iron desulfurization process is a method of removing hydrogen sulfide by wet oxidation using complex iron as a catalyst. The characteristic of this technology is that it can directly convert hydrogen sulfide in the gas into elemental S. The hydrogen sulfide content in the gas after desulfurization is usually less than 20ppm. It is a new desulfurization technology with simple process, high working sulfur capacity and environmental protection and non-toxicity. The complex iron desulfurization process can be widely used in the desulfurization of various sulfur-containing gases, including various hydrogen sulfide-containing waste gases, refinery gas, natural gas, amine method, low-temperature methanol washing, Selexol tail gas and Claus tail gas, as well as coal gasification units and synthetic ammonia plant process gases. The complex iron desulfurization technology has many advantages over the traditional desulfurization process. It overcomes the disadvantages of low sulfur capacity, complex desulfurization process, high secondary salt generation rate and serious environmental pollution in the traditional desulfurization process. At present, the complexing agents used more in the complex iron desulfurization process are ethylenediaminetetraacetic acid and N-hydroxyethylethylenediaminetriacetic acid, which have a high complexing ability for iron, but their sulfur capacity is low. Therefore, it is of great significance to develop a complex iron desulfurization process with high sulfur capacity. Summary of the invention

[0003] The invention provides an acid gas complex iron desulfurization process, which solves the problems of low sulfur capacity and high degradation rate of complex iron desulfurizer in the related art.

[0004] The technical solution of the present invention is as follows:

[0005] The present invention provides an acid gas complex iron desulfurization process, comprising the following steps:

[0006] S1, after the hydrogen sulfide gas is pressurized, it contacts the desulfurizer from bottom to top in the desulfurization tower in reverse direction for desulfurization, and then is discharged from the top of the desulfurization tower;

[0007] S2, after desulfurization, the bottom solution of the desulfurization tower is oxidized in an oxidation regeneration tower and then centrifuged to obtain sulfur;

[0008] The desulfurizer comprises the following raw materials in parts by weight: 15-20 parts of soluble iron salt, 50-60 parts of complexing agent, 0.8-1 parts of corrosion inhibitor, 20-30 parts of alkaline substance, 0.5-1 parts of sulfur precipitant, and 90-110 parts of water;

[0009] The complexing agent is a carboxyl-containing compound; the sulfur precipitating agent is composed of sodium polystyrene sulfonate, lignin sulfonate and polyoxyethylene ether.

[0010] As a further technical solution, the pressurization is performed by using a booster fan.

[0011] As a further technical solution, the hydrogen sulfide gas in S1 is pressurized by a booster fan, and then desulfurized by reverse contact with the desulfurizer from bottom to top in the desulfurization tower. The gas and water are separated by a demister at the top of the desulfurization tower, and the gas after the droplets are separated is discharged from the top of the desulfurization tower and enters the next gas use section.

[0012] As a further technical solution, the bottom solution of the desulfurization tower in S2 is oxidized in an oxidation regeneration tower, and the elemental sulfur is precipitated and separated by a filter press to obtain sulfur.

[0013] In the present invention, the solution at the bottom of the desulfurization tower is a divalent ferrous sulfur-containing rich liquid formed by the trivalent iron in the desulfurizer absorbing hydrogen sulfide in the hydrogen sulfide-containing gas. The divalent ferrous sulfur-containing rich liquid enters the oxidation regeneration tower. At the same time, the desulfurizer is pumped into the oxidation regeneration tower through the dosing system. The divalent ferrous sulfur-containing rich liquid undergoes an oxidation reaction with the air blown in by the oxidation blower under the catalytic action of the desulfurizer. The divalent ferrous sulfur-containing rich liquid is oxidized by the air blown in by the oxidation blower to become trivalent iron. At the same time, the oxidized elemental sulfur slowly settles to the bottom of the oxidation regeneration tower. When the sulfur solid content reaches about 15%, the bottom sulfur is pumped into a filter press for separation through a sulfur slurry pump. The upper solution after the sulfur is separated is transported to the desulfurization tower to continue to participate in the desulfurization process.

[0014] As a further technical solution, the carboxyl-containing compound includes one or more of tartaric acid, citric acid, butanetetracarboxylic acid, and 1,2,3,4-cyclobutanetetracarboxylic acid.

[0015] As a further technical solution, the complexing agent consists of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid.

[0016] In the present invention, by limiting the complexing agent to consist of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid, the sulfur capacity of the desulfurizing agent is further increased and the degradation rate is reduced.

[0017] As a further technical solution, the mass ratio of butanetetracarboxylic acid to 1,2,3,4-cyclobutanetetracarboxylic acid is 3-5:1.

[0018] In the present invention, by limiting the mass ratio of butanetetracarboxylic acid to 1,2,3,4-cyclobutanetetracarboxylic acid to 3-5:1, the sulfur capacity of the desulfurizer is further increased and the degradation rate is reduced.

[0019] As a further technical solution, the mass ratio of butanetetracarboxylic acid to 1,2,3,4-cyclobutanetetracarboxylic acid is 4:1.

[0020] As a further technical solution, the mass ratio of the sodium polystyrene sulfonate, lignin sulfonate and polyoxyethylene ether is 1:0.5:1-2.

[0021] In the present invention, by limiting the mass ratio of sodium polystyrene sulfonate, lignin sulfonate and polyoxyethylene ether to 1:0.5:1-2, the sulfur capacity of the desulfurizer is further increased and the degradation rate is reduced.

[0022] As a further technical solution, the mass ratio of the sodium polystyrene sulfonate, lignin sulfonate and polyoxyethylene ether is 1:0.5:1.5.

[0023] As a further technical solution, the molecular weight of the sodium polystyrene sulfonate is 80,000 to 100,000.

[0024] As a further technical solution, the polyoxyethylene ether includes one or more of octadecylamine polyoxyethylene ether, dodecylphenol polyoxyethylene ether, and oleyl alcohol polyoxyethylene ether.

[0025] As a further technical solution, the lignin sulfonate is calcium lignin sulfonate.

[0026] As a further technical solution, the soluble iron salt includes one or more of ferric chloride, ferric nitrate, and ferric sulfate.

[0027] As a further technical solution, the corrosion inhibitor is a molybdenum-based corrosion inhibitor.

[0028] As a further technical solution, the molybdenum-based corrosion inhibitor includes one or both of sodium molybdate and ammonium molybdate.

[0029] As a further technical solution, the alkaline substance includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0030] As a further technical solution, the preparation method of the desulfurizer comprises the following steps:

[0031] A1. Dissolving a soluble iron salt in water to obtain an iron salt solution;

[0032] A2. Add complexing agent, corrosion inhibitor and sulfur precipitant to the iron salt solution in sequence and stir, then add alkaline substance to obtain complex iron desulfurization agent.

[0033] The working principle and beneficial effects of the present invention are:

[0034] In the present invention, the desulfurization process adopts a complex iron desulfurizer with high sulfur capacity, which is not only suitable for the treatment of high-sulfur raw gas, but also has a small circulating liquid volume and can directly generate elemental sulfur. The complex iron desulfurizer can be recycled and reused, does not have the problem of secondary pollution, and can save resources. The complex iron desulfurizer is added with a complexing agent containing a carboxyl compound to complex with iron ions, thereby increasing the sulfur capacity of the complex iron desulfurizer and reducing the degradation rate; and the sulfur precipitant composed of sodium polystyrene sulfonate, lignin sulfonate and polyoxyethylene ether is added to further increase the sulfur capacity of the complex iron desulfurizer and reduce the degradation rate, thereby solving the problem of low sulfur capacity and high degradation rate of the complex iron desulfurizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] Figure 1 This is a schematic diagram of the process flow of complex iron desulfurization in Example 1 of the present invention;

[0037] In the figure, 1- desulfurization tower, 2- oxidation regeneration tower. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0039] In the following embodiments and comparative examples:

[0040] Sodium polystyrene sulfonate: model PSS30, molecular weight 80,000-100,000, purchased from Shandong Xinghai Chemical Co., Ltd.

[0041] Octadecenylamine polyoxyethylene ether, model NE-1815, purchased from Sangda Chemical (Nantong) Co., Ltd.;

[0042] Dodecylphenol polyoxyethylene ether, model 12D-9, purchased from Xingtai Xinlanxing Technology Co., Ltd.;

[0043] Oleyl alcohol polyoxyethylene ether, model 1605, was purchased from Yixing Jiateng Chemical Co., Ltd.

[0044] Example 1

[0045] like Figure 1 As shown, an acid gas complex iron desulfurization process comprises the following steps:

[0046] S1. After the hydrogen sulfide gas is pressurized by the booster fan, it contacts the desulfurizer from bottom to top in the desulfurization tower in reverse order for desulfurization, and then passes through the demister at the top of the desulfurization tower for gas-water separation. The gas after the droplets are separated is discharged from the top of the desulfurization tower and enters the next gas-using section;

[0047] S2. The sulfur-containing rich liquid in the bottom solution of the desulfurization tower enters the oxidation regeneration tower through the rich liquid pump. At the same time, the desulfurizer is pumped into the oxidation regeneration tower through the metering pump in the dosing system. The sulfur-containing rich liquid undergoes oxidation reaction with the air blown in by the oxidation blower under the catalytic action of the desulfurizer. At the same time, the oxidized elemental sulfur slowly settles to the bottom of the oxidation regeneration tower. When the sulfur solid content reaches about 15%, the bottom sulfur is pumped into the filter press for separation through the sulfur slurry pump. The upper solution after the sulfur is separated is transported to the desulfurization tower through the lean liquid pump to continue to participate in the desulfurization process.

[0048] The preparation method of the desulfurizer comprises the following steps:

[0049] A1. Dissolve 15 parts of ferric chloride in 90 parts of water to obtain an iron salt solution;

[0050] A2. Add 50 parts of tartaric acid, 0.8 parts of sodium molybdate, and 0.5 parts of sulfur precipitant to the iron salt solution in sequence, stir, and then add 20 parts of sodium hydroxide to obtain a complex iron desulfurizer.

[0051] The components of the sulfur precipitant include sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and octadeceneamine polyoxyethylene ether in a mass ratio of 1:0.5:3.

[0052] Example 2

[0053] An acid gas complex iron desulfurization process, same as Example 1.

[0054] The preparation method of the desulfurizer comprises the following steps:

[0055] A1. Dissolve 17 parts of ferric nitrate in 100 parts of water to obtain an iron salt solution;

[0056] A2. Add 55 parts of tartaric acid, 0.9 parts of ammonium molybdate, and 0.8 parts of sulfur precipitant to the iron salt solution in sequence, stir, and then add 25 parts of potassium hydroxide to obtain a complex iron desulfurizer.

[0057] The components of the sulfur precipitant include sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and dodecylphenol polyoxyethylene ether in a mass ratio of 1:0.5:3.

[0058] Example 3

[0059] An acid gas complex iron desulfurization process, same as Example 1.

[0060] The preparation method of the desulfurizer comprises the following steps:

[0061] A1. Dissolve 20 parts of ferric sulfate in 110 parts of water to obtain an iron salt solution;

[0062] A2. Add 60 parts of tartaric acid, 1 part of sodium molybdate, and 1 part of sulfur precipitant to the iron salt solution in sequence and stir, then add 30 parts of sodium carbonate to obtain a complex iron desulfurizer.

[0063] The components of the sulfur precipitant include sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and oleyl alcohol polyoxyethylene ether in a mass ratio of 1:0.5:3.

[0064] Example 4

[0065] The only difference between this embodiment and embodiment 3 is that the tartaric acid in the complexing agent is replaced by an equal amount of citric acid.

[0066] Example 5

[0067] The only difference between this embodiment and embodiment 3 is that the tartaric acid in the complexing agent is replaced by an equal amount of butanetetracarboxylic acid.

[0068] Example 6

[0069] The only difference between this embodiment and embodiment 3 is that the tartaric acid in the complexing agent is replaced by an equal amount of 1,2,3,4-cyclobutanetetracarboxylic acid.

[0070] Example 7

[0071] The only difference between this embodiment and embodiment 3 is that 60 parts of tartaric acid in the complexing agent are replaced by 30 parts of butanetetracarboxylic acid and 30 parts of 1,2,3,4-cyclobutanetetracarboxylic acid.

[0072] Example 8

[0073] The only difference between this embodiment and embodiment 7 is that the amount of butanetetracarboxylic acid added in the complexing agent is 55 parts, and the amount of 1,2,3,4-cyclobutanetetracarboxylic acid added is 5 parts.

[0074] Example 9

[0075] The only difference between this embodiment and embodiment 7 is that the amount of butanetetracarboxylic acid added in the complexing agent is 45 parts, and the amount of 1,2,3,4-cyclobutanetetracarboxylic acid added is 15 parts.

[0076] Example 10

[0077] The only difference between this embodiment and embodiment 7 is that the amount of butanetetracarboxylic acid added in the complexing agent is 48 parts, and the amount of 1,2,3,4-cyclobutanetetracarboxylic acid added is 12 parts.

[0078] Embodiment 11

[0079] The only difference between this embodiment and embodiment 7 is that the amount of butanetetracarboxylic acid added in the complexing agent is 50 parts, and the amount of 1,2,3,4-cyclobutanetetracarboxylic acid added is 10 parts.

[0080] Example 12

[0081] The only difference between this embodiment and embodiment 10 is that the components of the sulfur precipitant are composed of sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and oleyl alcohol polyoxyethylene ether in a mass ratio of 1:0.5:0.5.

[0082] Embodiment 13

[0083] The only difference between this embodiment and embodiment 12 is that the components of the sulfur precipitant are composed of sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and oleyl alcohol polyoxyethylene ether in a mass ratio of 1:0.5:1.

[0084] Embodiment 14

[0085] The only difference between this embodiment and embodiment 12 is that the components of the sulfur precipitant are composed of sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and oleyl alcohol polyoxyethylene ether in a mass ratio of 1:0.5:1.5.

[0086] Embodiment 15

[0087] The difference between this embodiment and embodiment 12 is that the components of the sulfur precipitant are composed of sodium polystyrene sulfonate (molecular weight 80,000-100,000), calcium lignin sulfonate, and oleyl alcohol polyoxyethylene ether in a mass ratio of 1:0.5:2.

[0088] Comparative Example 1

[0089] The only difference between this comparative example and Example 3 is that the sodium polystyrene sulfonate (molecular weight 8-10) is replaced by calcium lignin sulfonate and oleyl alcohol polyoxyethylene ether in a mass ratio of 0.5:3 in the sulfur precipitant.

[0090] Comparative Example 2

[0091] The only difference between this comparative example and Example 3 is that calcium lignin sulfonate is replaced by an equal amount of oleyl alcohol polyoxyethylene ether in the sulfur precipitant.

[0092] Comparative Example 3

[0093] The only difference between this comparative example and Example 3 is that the oleyl alcohol polyoxyethylene ether in the sulfur precipitant is replaced by an equal amount of calcium lignin sulfonate.

[0094] The test results of the sulfur capacity and degradation rate of the complex iron desulfurizer in Examples 1 to 15 and Comparative Examples 1 to 3 are shown in Table 1.

[0095] Sulfur capacity determination: the maximum mass of sulfur absorbed by a unit volume of desulfurizer;

[0096] The degradation rate after 50 cycles of desulfurization = (1-the content of iron ions in the desulfurizer after 50 cycles of desulfurization / the content of iron ions in the initial desulfurizer) × 100%.

[0097] Table 1 Test results of sulfur capacity and degradation rate of complex iron desulfurizers of Examples 1 to 15 and Comparative Examples 1 to 3

[0098]

[0099] Compared with Example 3, the sulfur capacity of the desulfurizer in Comparative Examples 1 to 3 is lower than that in Example 3, and the degradation rate is higher than that in Example 3, indicating that when the sulfur precipitating agent is composed of sodium polystyrene sulfonate, calcium lignin sulfonate, and oleyl alcohol polyoxyethylene ether, the sulfur capacity of the desulfurizer can be increased and the degradation rate can be reduced.

[0100] Compared with Example 3, the complexing agent in Example 4 is citric acid, the complexing agent in Example 5 is butanetetracarboxylic acid, the complexing agent in Example 6 is 1,2,3,4-cyclobutanetetracarboxylic acid, and the complexing agent in Example 7 is composed of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid. As a result, the sulfur capacity of the desulfurizer in Example 7 is higher than that in Examples 3 to 6, and the degradation rate is lower than that in Examples 3 to 6, indicating that when the complexing agent is composed of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid, the sulfur capacity of the desulfurizer can be further increased and the degradation rate can be reduced.

[0101] Compared with Example 7, Examples 8 to 11 change the mass ratio of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid in the complexing agent. As a result, the sulfur capacity of the desulfurizer in Examples 9 to 11 is higher than that in Examples 7 and 8, and the degradation rate is lower than that in Examples 7 and 8, indicating that when the mass ratio of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid is 3 to 5:1, the sulfur capacity of the desulfurizer can be further increased and the degradation rate can be reduced; by comparing Examples 9 to 11, it is found that the sulfur capacity of the desulfurizer in Example 10 is higher than that in Examples 9 and 11, and the degradation rate is lower than that in Examples 9 and 11, indicating that when the mass ratio of butanetetracarboxylic acid and 1,2,3,4-cyclobutanetetracarboxylic acid is 4:1, the obtained desulfurizer has the highest sulfur capacity and the lowest degradation rate.

[0102] Compared with Example 10, Examples 12 to 15 change the mass ratio of sodium polystyrene sulfonate (80,000 to 100,000), lignin sulfonate, and polyoxyethylene ether in the sulfur precipitant. As a result, the sulfur capacity of the desulfurizer in Examples 13 to 15 is higher than that in Examples 10 and 12, and the degradation rate is lower than that in Examples 10 and 12, indicating that when the mass ratio of sodium polystyrene sulfonate (80,000 to 100,000), lignin sulfonate, and polyoxyethylene ether is 1:0.5:1 to 2, the sulfur capacity of the desulfurizer can be further increased and the degradation rate can be reduced; by comparing Examples 13 to 15, it is found that the sulfur capacity of the desulfurizer in Example 14 is higher than that in Examples 13 and 15, and the degradation rate is lower than that in Examples 13 and 15, indicating that when the mass ratio of sodium polystyrene sulfonate (80,000 to 100,000), lignin sulfonate, and polyoxyethylene ether is 1:0.5:1.5, the obtained desulfurizer has the highest sulfur capacity and the lowest degradation rate.

[0103] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for desulfurization of acid gas complexed iron, characterized in that: The following steps are involved: S1, after the hydrogen sulfide gas is pressurized, it contacts the desulfurizer from bottom to top in the desulfurization tower in reverse direction for desulfurization, and then is discharged from the top of the desulfurization tower; S2, after desulfurization, the bottom solution of the desulfurization tower is oxidized in an oxidation regeneration tower and then centrifuged to obtain sulfur; The desulfurizer comprises the following raw materials in parts by weight: 15-20 parts of soluble iron salt, 50-60 parts of complexing agent, 0.8-1 parts of corrosion inhibitor, 20-30 parts of alkaline substance, 0.5-1 parts of sulfur precipitant, and 90-110 parts of water; The complexing agent is a carboxyl-containing compound; the sulfur precipitating agent is composed of sodium polystyrene sulfonate, lignin sulfonate, and polyoxyethylene ether; The complexing agent is composed of butane tetracarboxylic acid and 1,2,3,4-cyclobutane tetracarboxylic acid; The mass ratio of the butanetetracarboxylic acid to 1,2,3,4-cyclobutanetetracarboxylic acid is 3-5:

1.

2. The acid gas complex iron desulfurization process according to claim 1, characterized in that: The mass ratio of the sodium polystyrene sulfonate, lignin sulfonate and polyoxyethylene ether is 1:0.5:1-2.

3. The acid gas complex iron desulfurization process according to claim 1, characterized in that: The lignin sulfonate is calcium lignin sulfonate.

4. The acid gas complex iron desulfurization process according to claim 1, characterized in that: The polyoxyethylene ether includes one or more of octadecylamine polyoxyethylene ether, dodecylphenol polyoxyethylene ether, and oleyl alcohol polyoxyethylene ether.

5. The acid gas complex iron desulfurization process according to claim 1, characterized in that: The soluble iron salt includes one or more of ferric chloride, ferric nitrate and ferric sulfate.

6. The acid gas complex iron desulfurization process according to claim 1, characterized in that: The corrosion inhibitor is a molybdenum-based corrosion inhibitor.

7. The acid gas complex iron desulfurization process according to claim 1, characterized in that: The alkaline substance includes one or more of sodium hydroxide, potassium hydroxide and sodium carbonate.

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