Selective desulfurizer and method for removing acid gas in gas

Abstract

The invention provides a selective desulfurizer and a method for removing acid gas in gas. The selective desulfurizer comprises the following components in percentage by mass: 30-40% of organic amine A, 10-20% of organic amine B, 5-10% of an additive and 30-55% of water, the organic amine A comprises first organic amine and second organic amine, the first organic amine is methyldiethanolamine, and the second organic amine is monoethanolamine and / or diethanolamine; the mass ratio of the first organic amine to the second organic amine is (1-5): 1; the organic amine B comprises one or a combination of more than two of secondary amine 1, secondary amine 2 and secondary amine 3; the additive comprises one or a combination of more than two of phosphorous acid, hypophosphorous acid, metaphosphoric acid and pyrophosphoric acid. According to the technical scheme, carbonyl sulfide in the raw material natural gas can be selectively removed, carbon dioxide meeting the national standard is reserved, the defects of an existing process are overcome, and an efficient and green novel method is provided for natural gas purification.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas purification, and particularly relates to a selective desulfurizer and a method for removing acid gas from gas. Background Art

[0002] Industrial gases such as coal chemical industry, petrochemical industry, coke oven gas, natural gas and tail gas purification all contain organic sulfur, among which carbonyl sulfide (COS) is the most common. The existence of organic sulfur, on the one hand, will cause corrosion of instruments and equipment, poisoning and deactivation of catalysts, deterioration of chemical product quality and affect the utilization of tail gas in the chemical process. On the other hand, the untreated organic sulfur discharged into the atmosphere will form sulfur dioxide and further form acid rain. At the same time, the formed sulfate aerosol will cause the consumption of ozone in the atmosphere under the action of photochemical reaction, exacerbate the global warming effect, resulting in atmospheric environmental pollution, ecological environment damage and damage to human health. Therefore, the deep removal of organic sulfur is an important problem to be solved in related industries.

[0003] At present, the main methods for removing organic sulfur gas can be divided into wet method and dry method. The wet method is suitable for the situation of high organic sulfur concentration and large flue gas volume. Due to the poor activity of carbonyl sulfide, the conventional solvent method cannot meet the requirements of fine desulfurization. The net refinery usually uses a full-removal type desulfurization solvent to achieve this. Typical solvents include Sulfinol-X of Shell and HS-103 of Dow Chemical. Typical domestic ones include CT8-24 and CT8-28 solvents of Southwest Oil and Gas Field Company of PetroChina. Dry desulfurization is a treatment method that adsorbs or converts COS through an adsorbent or catalyst, and can achieve deep purification of organic sulfur. The catalytic hydrolysis method converts COS into H2S that is easier to purify after catalytic hydrolysis, and has the advantages of high conversion rate and low reaction temperature. However, the disadvantage of dry desulfurization technology is that it will increase the process of the entire purification process, require an external hydrolysis device, resulting in an increase in construction cost and operating cost.

[0004] In the field of natural gas purification, the full-removal type solvent can ensure that the product gas meets the standards smoothly. However, these solvents will remove all the CO2 in the raw material gas while removing carbonyl sulfide, resulting in a decrease in the commercial rate of the product gas, and an increase in energy consumption and flash vapor volume in the entire purification process, bringing pressure to the subsequent recovery device. Therefore, developing a new desulfurization technology system for selective removal of carbonyl sulfide is of great significance for related fields in terms of technological progress and economic benefits. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a selective desulfurizer and a method for removing acid gas from gas.

[0006] To achieve the above object, the present invention provides a selective desulfurizer. By mass percentage, the selective desulfurizer comprises the following components: 30-40% of organic amine A, 10-20% of organic amine B, 5-10% of additive, and 30-55% of water; the sum of the mass percentages of each component is 100%.

[0007] Among them, the organic amine A includes a first organic amine and a second organic amine. The first organic amine is methyldiethanolamine (MDEA), and the second organic amine is monoethanolamine (MEA) and / or diethanolamine (DEA); the mass ratio of the first organic amine to the second organic amine is 1-5:1.

[0008] The organic amine B includes one or a combination of two or more of secondary amine 1, secondary amine 2, and secondary amine 3.

[0009] The structural formulas of the secondary amine 1, secondary amine 2, and secondary amine 3 are shown in Formula I, Formula II, and Formula III respectively.

[0010]

[0011] The additive includes one or a combination of two or more of phosphorous acid, hypophosphorous acid, metaphosphoric acid, and pyrophosphoric acid.

[0012] In the above selective desulfurizer, preferably, the organic amine A is a combination of methyldiethanolamine and monoethanolamine with a mass ratio of 1.6-4:1, or a combination of methyldiethanolamine and diethanolamine with a mass ratio of 2.3-4:1.

[0013] According to a specific embodiment of the present invention, preferably, by mass percentage, the selective desulfurizer comprises the following components: 25-32% of methyldiethanolamine, 8-15% of monoethanolamine and / or diethanolamine, 10-18% of organic amine B, 5-9% of additive, and 36-45% of deionized water; the sum of the mass percentages of each component is 100%.

[0014] The selective desulfurizer of the present invention is a carbonyl sulfide desulfurizer. It uses a macrocyclic secondary amine and a tertiary amine such as MDEA for compounding as the main formula of the carbonyl sulfide removal solvent. Both compounds contain an N atom rich electron center. Among them, MDEA contains a hydrophilic functional group of hydroxyl. Through the intermolecular hydrogen bond interaction of the two compounds, the solvation effect of the compounded solution is promoted. The cyclic structure of the macrocyclic secondary amine plays a role in selectively removing carbonyl sulfide with more obvious molecular polarization degree in space.

[0015] The selective desulfurizer of the present invention can improve the stability of the alkalinity of the system by adding an additive, providing a guarantee for the long-term operation of the system.

[0016] The preparation method of the selective desulfurizer provided by the present invention may include the following steps: according to the mass percentages of each component, add organic amine A, organic amine B, and an additive to deionized water, and after mixing evenly, obtain the selective desulfurizer.

[0017] The present invention also provides a method for removing acid gas from a gas, which uses the above-mentioned selective desulfurizer.

[0018] In the above method, preferably, the gas is sour sulfur-containing natural gas.

[0019] In the above method, preferably, the acid gas includes one or a combination of two or more of hydrogen sulfide, carbonyl sulfide, carbon disulfide, mercaptan, and carbon dioxide.

[0020] In the above method, preferably, the content of carbonyl sulfide in the gas is 50 - 500 mg / m 3 .

[0021] In the method for removing carbonyl sulfide from a gas according to the present invention, by adjusting the additive in the carbonyl sulfide scavenger, the compound solution can have better desulfurization selectivity, efficiently and targetedly remove the difficult-to-remove carbonyl sulfide component in the raw material gas, and by adjusting the additive, a certain content of carbon dioxide can be selectively retained, improving the commercial rate of the product gas.

[0022] In the above method, preferably, the product gas obtained after removing the acid gas still contains carbon dioxide.

[0023] In the above method, preferably, the content of carbon dioxide in the product gas obtained after removing the acid gas is 0.5 v% - 2.5 v%.

[0024] In the above method, preferably, the method further includes a step of heating and regenerating the selective desulfurizer after absorbing the acid gas.

[0025] The present invention can selectively remove carbonyl sulfide from the raw material natural gas and retain carbon dioxide meeting the national standards through a technology for selectively removing carbonyl sulfide, can solve the deficiencies of the existing process, and provides an efficient and green new method for natural gas purification.

[0026] The technical solution provided by the present invention has the following beneficial effects:

[0027] (1) By adding organic amine B and an additive, the selective desulfurizer of the present invention can improve the selective desulfurization ability of the selective desulfurizer for carbonyl sulfide.

[0028] (2) The selective desulfurizer of the present invention exhibits good selectivity in the reaction of absorbing acid gas. In particular, it has a good effect on the absorption of carbonyl sulfide. It can retain less than 3% of CO2 content on the premise of ensuring qualified gas quality, which provides the possibility to improve the commercial rate of the product gas in the natural gas purification process.

[0029] (3) The selective desulfurizer provided by the present invention has good regeneration effect. It can be regenerated by heating to restore the function of absorbing acid gas for recycling. After being recycled 100 times in the laboratory, it still maintains good absorption performance. The selective desulfurizer of the present invention has the advantages of convenient use method and being suitable for large-scale applications with a treatment volume of more than one million cubic meters per day. Detailed implementation manners

[0030] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0031] Example 1

[0032] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0033] By mass percentage, the selective desulfurizer of this example includes the following components: MDEA 25% + MEA 15%, secondary amine 1 10%, phosphorous acid 5%, deionized water 45%.

[0034] Test method: Load the selective desulfurizer (lean liquid) into the absorption reactor (2L), and introduce the raw gas from the bottom of the absorption reactor to make the raw gas contact with the selective desulfurizer for acid gas absorption reaction;

[0035] Discharge the purified gas from the top of the absorption reactor, and detect the remaining components in the purified gas after cooling; Stop introducing the raw gas when the acid gas concentration in the purified gas reaches the set value;

[0036] During the reaction, the reacted selective desulfurizer enters the regeneration tower for heating regeneration, and the regenerated selective desulfurizer returns to the absorption reactor to participate in the reaction.

[0037] Among them, the packing height of the selective desulfurizer, the temperature of the lean liquid, and the flow rate of the raw gas are shown in Table 1;

[0038] The circulation amount of the selective desulfurizer is controlled by the flow rate of the circulation pump between the absorption reactor and the regeneration tower, as shown in Table 1 specifically.

[0039] The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 1.

[0040] Table 1

[0041]

[0042] Example 2

[0043] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0044] By mass percentage, the selective desulfurizer of this example includes the following components: MDEA 25% + MEA 15%, secondary amine 2 10%, phosphorous acid 5%, deionized water 45%.

[0045] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer of this example for removing CO2 and COS are shown in Table 2.

[0046] Table 2

[0047]

[0048] Example 3

[0049] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0050] By mass percentage, the selective desulfurizer of this example includes the following components: MDEA 25% + MEA 15%, secondary amine 3 10%, phosphorous acid 5%, deionized water 45%.

[0051] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer of this example for removing CO2 and COS are shown in Table 3.

[0052] Table 3

[0053]

[0054] It can be seen from the above data that when the proportion of each component of the solvent is fixed, secondary amine 1 is the most preferred under the current proportion. The content of sulfur-containing gas (hydrogen sulfide + carbonyl sulfide) in the purified gas is the lowest, and the carbon dioxide content is the highest, meeting the purpose of the present invention. Further, the components are further optimized in subsequent examples.

[0055] Example 4

[0056] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0057] By mass percentage, the selective desulfurizer of this example includes the following components: MDEA 25% + MEA 10%, secondary amine 1 15%, hypophosphorous acid 5%, deionized water 45%.

[0058] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 4.

[0059] Table 4

[0060]

[0061] Example 5

[0062] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0063] By mass percentage, the selective desulfurizer in this example includes the following components: MDEA 28% + MEA 10%, secondary amine 1 15%, metaphosphoric acid 5%, deionized water 42%.

[0064] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 5.

[0065] Table 5

[0066]

[0067] Example 6

[0068] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0069] By mass percentage, the selective desulfurizer in this example includes the following components: MDEA 32% + DEA 8%, secondary amine 1 18%, pyrophosphoric acid 5%, deionized water 37%.

[0070] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 6.

[0071] Table 6

[0072]

[0073] Example 7

[0074] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0075] By mass percentage, the selective desulfurizer in this example includes the following components: MDEA 28% + DEA 12%, secondary amine 1 15%, pyrophosphoric acid 9%, deionized water 36%.

[0076] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 7.

[0077] Table 7

[0078]

[0079] Example 8

[0080] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0081] By mass percentage, the selective desulfurizer in this example comprises the following components: MDEA 32% + MEA 8%, secondary amine 1 15%, pyrophosphoric acid 7%, deionized water 38%.

[0082] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 8.

[0083] Table 8

[0084]

[0085] Example 9

[0086] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0087] By mass percentage, the selective desulfurizer in this example comprises the following components: MDEA 30% + DEA 10%, secondary amine 1 14%, pyrophosphoric acid 8%, deionized water 38%.

[0088] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 9.

[0089] Table 9

[0090]

[0091] Example 10

[0092] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0093] By mass percentage, the selective desulfurizer in this example comprises the following components: MDEA 30% + MEA 10%, secondary amine 1 16%, phosphorous acid 8%, deionized water 36%.

[0094] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 10.

[0095] Table 10

[0096]

[0097] Example 11

[0098] This example provides a selective desulfurizer and a method for removing carbonyl sulfide from gas by using the same, which are as follows:

[0099] By mass percentage, the selective desulfurizer of this example includes the following components: MDEA 28% + DEA 10%, secondary amine 1 12%, metaphosphoric acid 6%, deionized water 44%.

[0100] The test method of this example is the same as that of Example 1. The test data of the selective desulfurizer in this example for removing CO2 and COS are shown in Table 11.

[0101] Table 11

[0102]

[0103] Comparative Example 1

[0104] In this comparative example, MDEA, MEA, and DEA aqueous solutions were respectively used to remove carbonyl sulfide from gas. The specific process parameters are as follows: packing height 1.0 m, lean liquid temperature 39 °C, raw gas flow rate 300 L / h, circulation rate 3.0 L / h.

[0105] By mass percentage, this comparative example respectively includes the following components: 1. MDEA 50%, deionized water 50%; 2. MEA 50%, deionized water 50%; 3. DEA 50%, deionized water 50%.

[0106] The test method of this comparative example is the same as that of Example 1. The test data of the solvents selected in this comparative example for removing CO2 and COS are shown in Table 12.

[0107] Table 12

[0108]

[0109] Comparative Example 2

[0110] In this comparative example, aqueous solutions of secondary amine 1, secondary amine 2, and secondary amine 3 were separately used to remove carbonyl sulfide from gas. The specific process parameters are as follows: packing height 1.0 m, lean liquid temperature 39 °C, raw gas flow rate 300 L / h, circulation rate 3.0 L / h.

[0111] By mass percentage, this comparative example includes the following components: 1. Secondary amine 1: 50%, deionized water: 50%; 2. Secondary amine 2: 50%, deionized water: 50%; 3. Secondary amine 3: 50%, deionized water: 50%.

[0112] The test method of this comparative example is the same as that of Example 1. The test data of the solvent used in this comparative example for removing CO2 and COS are shown in Table 13.

[0113] Table 13

[0114]

[0115] Comparative Example 3 (compared with Example 1, the solvent component reduces secondary amine 1)

[0116] This comparative example provides a desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0117] By mass percentage, the desulfurizer of this comparative example includes the following components: MDEA 25% + MEA 15%, phosphorous acid 5%, deionized water 55%.

[0118] The test method of this comparative example is the same as that of Example 1. The test data of the desulfurizer of this comparative example for removing CO2 and COS are shown in Table 14.

[0119] Table 14

[0120]

[0121] Comparative Example 4 (compared with Example 1, the solvent component reduces phosphorous acid)

[0122] This comparative example provides a desulfurizer and a method for removing carbonyl sulfide from gas, which are as follows:

[0123] By mass percentage, the selective desulfurizer of this example includes the following components: MDEA 25% + MEA 15%, secondary amine 1 10%, deionized water 50%.

[0124] The test method of this comparative example is the same as that of Example 1. The test data of the desulfurizer of this comparative example for removing CO2 and COS are shown in Table 15.

[0125] Table 15

[0126]

[0127] It can be seen from the test data in Tables 4 - 15 that: compared with the conventional desulfurization solvent, the selective desulfurizer of the present invention can improve the purification degree of raw natural gas, and can reduce the carbon dioxide removal rate while deeply removing carbonyl sulfide, improve the acid gas quality, and increase the product gas commercial rate.

[0128] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A selective desulfurizer, by mass percentage, the selective desulfurizer comprises the following components: 30-40% of organic amine A, 10-20% of organic amine B, 5-10% of additive, and 30-55% of water; Among them, The organic amine A comprises a first organic amine and a second organic amine, wherein the first organic amine is methyldiethanolamine, and the second organic amine is monoethanolamine and / or diethanolamine; the mass ratio of the first organic amine to the second organic amine is 1-5:1; The organic amine B comprises one or a combination of two or more of secondary amine 1, secondary amine 2, and secondary amine 3; The structural formulas of the secondary amine 1, secondary amine 2, and secondary amine 3 are respectively shown as Formula I, Formula II, and Formula III: The additive comprises one or a combination of two or more of phosphorous acid, hypophosphorous acid, metaphosphoric acid, and pyrophosphoric acid.

2. The selective desulfurizer according to claim 1, wherein The organic amine A is a combination of methyldiethanolamine and monoethanolamine with a mass ratio of 1.6-4:1, or a combination of methyldiethanolamine and diethanolamine with a mass ratio of 2.3-4:

1.

3. The selective desulfurizer according to claim 1 or 2, wherein, By mass percentage, the selective desulfurizer comprises the following components: 25-32% of methyldiethanolamine, 8-15% of monoethanolamine and / or diethanolamine, 10-18% of organic amine B, 5-9% of additive, and 36-45% of deionized water.

4. A method for removing acid gas from a gas, which is carried out by using the selective desulfurizer according to any one of claims 1-3.

5. The method according to claim 4, wherein, The gas is sour sulfur-containing natural gas.

6. The method according to claim 4, wherein The acid gas comprises one or a combination of two or more of hydrogen sulfide, carbonyl sulfide, carbon disulfide, mercaptan, and carbon dioxide.

7. The method according to claim 6, wherein The content of carbonyl sulfide in the gas is 50 - 500 mg / m 3 .

8. The method according to claim 4, wherein The product gas obtained after removing the acid gas still contains carbon dioxide.

9. The method according to claim 8, wherein, The content of carbon dioxide in the product gas obtained after removing the acid gas is 0.5v%-2.5v%.

10. The method according to claim 4, wherein, The method further comprises a step of heating and regenerating the selective desulfurizer after absorbing the acid gas.

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