Decarburization solvents, decarburization methods and systems for carbon-containing natural gas

Abstract

The present application relates to the field of natural gas decarburization, and discloses a decarburization solvent, a decarburization method and system of carbon-containing natural gas, the decarburization solvent comprising a main agent, an activator and an auxiliary agent; wherein the main agent is N-methyldiethanolamine, the activator comprises a primary amine and a secondary amine, and the auxiliary agent is selected from at least one of potassium sorbate, sodium sorbate and sodium sulfite.The decarburization solvent and the decarburization method provided by the present application can not only make the absorption and regeneration equipment flexible to follow the change of the CO2 content of the raw gas in the natural gas development process and expand, but also avoid the corrosion and foaming of the tower equipment in the conventional process; meanwhile, the absorption and regeneration performance of the decarburization solution can be improved under the condition of meeting the purification index, and the regeneration heat consumption and the power consumption for pressurization of the amine liquid circulation can be greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of natural gas decarburization, in particular to a decarburization solvent, a decarburization method and system for carbon-containing natural gas. BACKGROUND

[0002] Natural gas is a high-quality, efficient and clean low-carbon energy source, and plays an important role in the process of global carbon dioxide emission reduction. There are many natural gases containing carbon dioxide (CO2) or even high-carbon natural gases, that is, the molar fraction content of CO2 in these natural gases is at least more than 3%, the high-carbon natural gas is at least more than 10%, and even as high as 30%.

[0003] According to the standards of our country, the molar fraction content of CO2 in natural gas is regulated: no more than 3% for the first type of gas, and no more than 4% for the second type of gas. The natural gas entering the long-distance pipeline is considered as the first type of gas. Therefore, for the above-mentioned natural gas, it needs to be treated to meet the standard requirements so that it can be suitable for pipeline transportation.

[0004] There are many mature industrial processes for removing CO2 from natural gas, among which the chemical absorption method is the most widely used method, especially the absorption method using amine solvents. The decarburization method using amine solvents includes two aspects: one is the decarburization solvent, and the other is the use method of the decarburization solvent, that is, the decarburization process. The general amine solvent type decarburization solvent mainly includes monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) formula solvent. The decarburization solvent is generally carried out through an absorption tower and a regeneration tower, and no matter whether the tower internals are packing, trays or a mixed way of packing and trays, the decarburization requirement can be achieved. In the decarburization process, for the molar fraction content of CO2 in the raw material natural gas being 4% to 10%, the decarburization process is relatively simple, and the cost is not high; but when the molar fraction content of CO2 in the natural gas is higher than 10%, especially for high-carbon natural gas, the decarburization solution circulation amount is large, resulting in large power consumption and regeneration heat consumption, and the decarburization cost becomes challenging, and at the same time, the decarburization cost is also increased due to corrosion, foaming and other problems. Therefore, it is urgent to find a decarburization solvent and decarburization method for effectively separating CO2 in high-carbon natural gas. SUMMARY

[0005] The purpose of the present application is to overcome the low decarburization efficiency of the prior art for high-carbon natural gas, to realize a large decarburization solution circulation amount (i.e. low gas-liquid ratio) for a certain treatment load, and to provide a decarburization solvent, a decarburization method and system for carbon-containing natural gas.

[0006] In order to achieve the above object, the present application provides a decarburization solvent, which comprises a main agent, an activator and an auxiliary agent; the main agent is N-methyldiethanolamine, the activator comprises a primary amine and a secondary amine, and the auxiliary agent is at least one selected from potassium sorbate, sodium sorbate and sodium sulfite.

[0007] The present application provides a decarburization method of carbon-containing natural gas, which comprises the following steps:

[0008] (1) contacting lean amine solution with carbon-containing natural gas in the presence of hydrophilic hollow fiber membranes to perform absorption, to obtain rich amine solution and decarburized natural gas;

[0009] (2) desorbing the rich amine solution in the presence of hydrophobic hollow fiber membranes to obtain regenerated lean amine solution which is returned to step (1);

[0010] The CO2 content in the carbon-containing natural gas is 4-30 mol%.

[0011] The present application provides a decarburization system of carbon-containing natural gas, which comprises:

[0012] a pretreatment unit, an absorber, a purified gas separator, a regenerator and a CO2 separator; wherein,

[0013] The pretreatment unit is used for refining the carbon-containing natural gas to obtain refined carbon-containing natural gas.

[0014] The absorber is used for contacting and absorbing the refined carbon-containing natural gas and lean amine solution to obtain decarburized natural gas which enters the purified gas separator, and the lean amine solution absorbs CO2 to obtain rich amine solution.

[0015] The regenerator is used for desorbing CO2 from the rich amine solution to obtain regenerated lean amine solution which is fed into the absorber, and CO2 which enters the CO2 separator.

[0016] The absorber comprises m membrane absorbers, and the membrane absorbers are provided with hydrophilic hollow fiber membranes; the regenerator comprises n membrane regenerators, and the membrane regenerators are provided with hydrophobic hollow fiber membranes; wherein, m≥1 and n≥1.

[0017] Through the above technical solution, the decarburization solvent and the decarburization method provided by the present application can not only make the absorption and regeneration equipment flexible to follow the change of the CO2 content of the raw gas in the natural gas development process and expand, but also avoid the corrosion and foaming of the tower equipment in the conventional process; at the same time, the absorption and regeneration performance of the decarburization solution can be improved under the condition of meeting the purification index, and the regeneration heat consumption and the power consumption for boosting of the amine liquid circulation can be greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a decarbonization system for carbon-containing natural gas in an embodiment of the present application.

[0019] Reference Signs List

[0020] 1 Absorber 2 Regenerator 3 Multistage filter

[0021] 4 Purified gas separator 5 Rich liquid heat exchanger 6 Flash tank

[0022] 7 First rich liquid suction pump 8 Second rich liquid suction pump 9 First cooler

[0023] 10 Lean amine liquid pump 11 Second cooler 12 CO2 separator

[0024] 13 Agglomerated filter 14 Third cooler DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are provided as approximate descriptions of the ranges and are understood to be open-ended. Each range is a continuum of values between the upper and lower limits of that range and includes integers within that range. Discrete values can be derived from the continuum but the derived values are also included in the overall ranges. For example, the range of "1 to 5" is understood to include the values 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, and 5.5, etc. It will be further understood that the endpoints of the ranges are included in the range. Still further, a number of the ranges given herein are understood to be approximate such that slight variations of the upper and lower limits of the ranges are included in the ranges. It is also understood that it is within the scope to make substitutions to components of the compositions, methods and processes of the present application with like components.

[0026] The first aspect of the present application provides a decarbonization solvent, which comprises a main agent, an activator and an auxiliary agent; wherein the main agent is N-methyldiethanolamine, the activator comprises primary amine and secondary amine, and the auxiliary agent is selected from at least one of potassium sorbate, sodium sorbate and sodium sulfite.

[0027] For carbon-containing natural gas, especially high-carbon-content natural gas, in a conventional absorption process, the decarbonization solvent directly contacts with the carbon-containing natural gas and is easy to foam. The inventors of the present application found in experiments that the auxiliary agent in the present application is easy to dissolve and does not generate precipitate in actual use, which helps to maintain the stability of the decarbonization solution, reduce the generation of heat stable salts, and improve the rich liquid regeneration and defoaming performance in the use of traditional gas-liquid direct contact. In combination with MDEA and the activator, the efficiency of CO2 absorption and desorption can be further improved, the gas-liquid ratio is increased, and thus the overall reaction energy consumption is reduced.

[0028] According to a preferred embodiment of the present application, the primary amine is selected from hydroxyethyl diamine and / or 2-amino-2-methyl-1,3-propanediol.

[0029] According to a preferred embodiment of the present application, the secondary amine is selected from at least one of 2,5-dimethylolpiperazine, 3,6-dimethylolpiperazine, 2,3-dimethylolpiperazine, and 5,6-dimethylolpiperazine.

[0030] Through the above preferred embodiment, the absorption speed is improved while the regeneration is facilitated.

[0031] According to a preferred embodiment of the present application, the content of the main agent is 80-95% by mass, the content of the activating agent is 5-20% by mass, and the content of the auxiliary agent is 0.05-0.25% by mass, based on the total mass of the decarburization solvent; further preferably, the content of the main agent is 85-93% by mass, the content of the activating agent is 7-15% by mass, and the content of the auxiliary agent is 0.08-0.2% by mass. Under the above preferred embodiment, the comprehensive absorption and regeneration performance and stability of the decarburization solution are improved.

[0032] According to a preferred embodiment of the present application, the mass ratio of the primary amine to the secondary amine is 1:1-4, preferably 1:1.5-3. The ratio of the primary amine to the secondary amine affects the mass transfer absorption effect, and too little or too much primary amine can lead to reduced CO2 absorption / desorption efficiency.

[0033] The second aspect of the present application provides a decarburization method of carbon-containing natural gas, comprising the following steps:

[0034] (1) contacting lean amine solution with carbon-containing natural gas in the presence of hydrophilic hollow fiber membrane to perform absorption, to obtain rich amine solution and decarburized natural gas;

[0035] (2) desorbing the rich amine solution in the presence of hydrophobic hollow fiber membrane to obtain regenerated lean amine solution, which is returned to step (1);

[0036] Among them, the CO2 content in the carbon-containing natural gas is 4-30 mol%.

[0037] According to a preferred embodiment of the present application, the CO2 content in the carbon-containing natural gas is 8-25 mol%.

[0038] Through the above absorption and regeneration of different properties of hydrophilic hollow fiber membrane and hydrophobic hollow fiber membrane, the CO2 transfer efficiency from the gas to the lean amine solution and the CO2 regeneration efficiency in the rich amine solution can be greatly improved.

[0039] According to a preferred embodiment of the present application, the lean amine solution contains the decarburization solvent provided by the first aspect of the present application and water; preferably, the concentration of the decarburization solvent is 45-55% by mass based on the total mass of the lean amine solution. With the above preferred embodiment, the absorption and regeneration performance can be improved and the heat consumption of regeneration and the power consumption of circulating solution can be reduced.

[0040] According to a preferred embodiment of the present application, the contact angle of the inner and outer surfaces of the hydrophilic hollow fiber membrane to water is not more than 10 degrees; the contact angle of the inner and outer surfaces of the hydrophobic hollow fiber membrane to water is not less than 150 degrees, preferably more than 160 degrees.

[0041] In the present application, the material of the hydrophilic hollow fiber membrane is not particularly limited and can be obtained by commercial purchase or conventional preparation as long as the hydrophilicity requirement is met. Preferably, the hydrophilic hollow fiber membrane is a membrane material containing amine / amino functional groups or a coating layer with fixed amine / amino groups on the inner and outer surfaces.

[0042] According to a preferred embodiment of the present application, the outer diameter of the hydrophilic hollow fiber membrane or the hydrophobic hollow fiber membrane is 0.6-3 mm, preferably 0.8-2.5 mm, and the inner diameter is 0.3-2.6 mm, preferably 0.5-2 mm.

[0043] According to a preferred embodiment of the present application, the pore size of the hydrophilic hollow fiber membrane or the hydrophobic hollow fiber membrane is 0.05-3 μm, preferably 0.8-2.6 μm; the porosity is 40-85%, preferably 55-80%; and the pure water flux of the hydrophilic hollow fiber membrane or the hydrophobic hollow fiber membrane is 1000-5000 L / (m 2 ·h·bar) and the strength is ≥4 MPa. With the above preferred conditions, a better gas-liquid mass transfer interface can be provided and the mass transfer efficiency can be improved.

[0044] According to a preferred embodiment of the present application, the pressure of the carbon-containing natural gas is 2-8 MPa, preferably 3-6 MPa. With the above preferred pressure of the carbon-containing natural gas, the absorption efficiency can be ensured and the service life of the fiber membrane can be prolonged.

[0045] According to a preferred embodiment of the present application, the temperature of the lean amine solution is 40-75°C, preferably 50-65°C.

[0046] According to a preferred embodiment of the present application, the method further includes adjusting the temperature of the rich amine solution of step (1) and / or flashing to obtain an adjusted temperature rich amine solution and flash gas; and the flash gas is used as fuel gas.

[0047] According to a preferred embodiment of the present application, the temperature of the temperature-adjusted rich amine solution is 65-85℃, preferably 70-75℃.

[0048] According to a preferred embodiment of the present application, the pressure of the flashing is 0.5-0.8 MPa.

[0049] According to a preferred embodiment of the present application, the desorption of the rich amine solution in step (2) is performed by vacuum suction; the rich amine solution enters the hydrophobic hollow fiber membrane, and the regeneration of the rich amine solution to the lean amine solution is realized by vacuum suction.

[0050] In the present application, the desorption of the rich amine solution can be completed by using a lower vacuum degree. According to a preferred embodiment of the present application, the vacuum degree of the vacuum suction is 10-50 kPa, preferably 20-40 kPa.

[0051] The third aspect of the present application provides a decarbonization system of carbon-containing natural gas, wherein the decarbonization system comprises:

[0052] a pretreatment unit, an absorber, a purified gas separator, a regenerator and a CO2 separator; wherein,

[0053] The pretreatment unit is configured to refine the carbon-containing natural gas to obtain refined carbon-containing natural gas.

[0054] The absorber is configured to contact and absorb the refined carbon-containing natural gas and the lean amine solution to obtain decarbonized natural gas entering the purified gas separator, and the lean amine solution after absorbing CO2 to obtain the rich amine solution.

[0055] The regenerator is configured to desorb CO2 from the rich amine solution to obtain regenerated lean amine solution entering the absorber, and CO2 entering the CO2 separator.

[0056] The absorber comprises m membrane absorbers, and the membrane absorbers are provided with hydrophilic hollow fiber membranes; the regenerator comprises n membrane regenerators, and the membrane regenerators are provided with hydrophobic hollow fiber membranes; wherein m≥1 and n≥1.

[0057] According to a preferred embodiment of the present application, the decarbonization system further comprises a flasher, which is configured to flash the rich amine solution flowing out of the absorber and send it into the regenerator, and the flash gas is used as fuel gas. In the present application, the flasher can be set or not set according to the need, and those skilled in the art can understand that when the flasher is not set, the rich amine solution directly enters the regenerator from the absorber.

[0058] According to a preferred embodiment of the present application, the pre-treatment unit comprises a coalescence separator and / or a multi-stage filter, preferably, the coalescence separator has a removal rate of no less than 99% for liquid droplets of 1 μm or above, and the multi-stage filter has a removal rate of no less than 99% for solid particulate matter of 1 μm or above.

[0059] According to a preferred embodiment of the present application, the absorber comprises m membrane absorbers, wherein 1≤m≤5. In the present application, the refined carbon-containing natural gas enters the hydrophilic hollow fiber membrane in the membrane absorber, and the lean amine liquid membrane absorber shell is in countercurrent contact with the refined carbon-containing natural gas to absorb CO2. The bidirectional flow of the lean amine liquid and the refined carbon-containing natural gas allows the lean amine liquid to continuously update the contact surface with the membrane surface during the absorption process, which is beneficial to improve the mass transfer efficiency, increase the CO2 absorption efficiency, and improve the processing load, thereby meeting the industrialization requirements.

[0060] According to a preferred embodiment of the present application, the regenerator comprises n membrane regenerators, wherein 1≤n≤5.

[0061] According to a preferred embodiment of the present application, the membrane regenerators are in a vacuum atmosphere, preferably, the vacuum degree is 10-50 kPa. When n>1, the vacuum degree of each membrane regenerator increases in turn along the flow direction from upstream to downstream, and the pressure difference between adjacent two membrane regenerators is 5-10 kPa. The use of the above preferred embodiment is beneficial to save the regeneration energy consumption and improve the rich liquid regeneration effect.

[0062] According to a preferred embodiment of the present application, the lean amine liquid flowing out of the regenerator is cooled and then sent into the absorber through pressure regulation for repeated use. The pressure of the amine liquid circulating in the absorber and the regenerator only needs to meet the acid gas load and overcome the pressure loss of the conveying pipeline, the absorber and the regenerator. Compared with the absorption mode of the absorption tower in the traditional decarbonization process, the operation pressure is greatly reduced.

[0063] In the present application, the membrane absorber and the membrane regenerator can be selected from conventional membrane contactors, and the shell of the membrane contactor can be stainless steel, glass fiber reinforced plastic or high-strength fiber.

[0064] According to the present application, the types and ranges of the hydrophilic hollow fiber membrane and the hydrophobic hollow fiber membrane are the same as those described above, and will not be repeated here.

[0065] According to a preferred embodiment of the present application, the filling rate of the hydrophilic hollow fiber membrane in the membrane absorber is 60-95% by volume, preferably 75-85% by volume.

[0066] According to a preferred embodiment of the present application, the packing ratio of the hydrophobic hollow fiber membranes in the membrane regenerator is 60-95% by volume; preferably 75-85% by volume.

[0067] The present application will be described in detail below by way of examples.

[0068] In the following examples, the lean amine liquid circulation amount is the same, and the gas-liquid ratio is the ratio of the absorption tower processing gas amount to the lean amine liquid circulation amount. The higher the gas-liquid ratio, the greater the processing load of the absorption tower, and the less the absorption liquid circulation amount used for the same processing amount, and the less the energy consumption.

[0069] Example 1

[0070] The decarburization solvent composition is 93% by mass of MDEA, a total amount of 6.9% by mass of activator, wherein the mass ratio of 2-amino-2-methyl-1,3-propanediol and 2,5-dihydroxymethylpiperazine is 1:1.5, and 0.1% by mass of sodium sulfite. The decarburization solvent is diluted with desalted water to 50% by mass to obtain lean amine liquid, and the lean amine liquid is heated to 55°C and fed into the absorber.

[0071] The decarburization system used is as shown in Figure 1 The hydrophilic hollow fiber membrane packing ratio in the membrane absorber is 80%, the hollow fiber inner diameter is 1 mm, the outer diameter is 1.6 mm, the length is 1000 mm, the pore size on the surface of the hollow fiber is 0.06-1 μm, the porosity is 75%, the pure water flux is about 4000 L / (m 2 ·h·bar), the strength is 5.5 MPa, and the inner surface contact angle of the membrane absorber is 8.5 degrees.

[0072] The hydrophobic hollow fiber membrane packing ratio in the membrane regenerator is 80%, the hollow fiber inner diameter is 1.2 mm, the outer diameter is 1.7 mm, the length is 1000 mm, the pore size on the surface of the hollow fiber is 0.06-1 μm, the porosity is 75%, the pure water flux is about 3500 L / (m 2 ·h·bar), the strength is 5.5 MPa, and the inner surface contact angle of the membrane absorber is 163 degrees; the regenerator vacuum degree is 25 kPa.

[0073] The carbon-containing natural gas simulation gas pressure is 4 MPa at room temperature, wherein the CO2 content is 12% by mole, and the rest is N2.

[0074] The test results are shown in Table 1.

[0075] Example 2

[0076] The method in Example 1 is followed, except that the MDEA content in the decarburization solvent is 85% by mass, the total amount of the activator is 14.8% by mass, the mass ratio of 2-amino-2-methyl-1,3-propanediol and 3,6-dihydroxymethylpiperazine is 1:3, and the sodium sorbate content is 0.2% by mass.

[0077] The test results are shown in Table 1.

[0078] Example 3

[0079] The method in Example 1 is followed, except that the MDEA content in the decarburization solvent is 90% by mass, the total amount of the activator is 9.9% by mass, the mass ratio of 2-amino-2-methyl-1,3-propanediol and 3,6-dihydroxymethylpiperazine is 1:1.7, and the potassium sorbate content is 0.1% by mass.

[0080] The test results are shown in Table 1.

[0081] Example 4

[0082] The method in Example 3 is followed, except that the vacuum degree of the regenerator exhaust gas is 35 kPa.

[0083] The test results are shown in Table 1.

[0084] Example 5

[0085] The method in Example 4 is followed, except that the CO2 content in the carbon-containing natural gas is 20% by mole.

[0086] The test results are shown in Table 1.

[0087] Example 6

[0088] The method in Example 5 is followed, except that the lean amine solution is heated to 65°C before being fed into the absorber.

[0089] The test results are shown in Table 1.

[0090] Example 7

[0091] The method in Example 1 is followed, except that two membrane absorbers are provided in the absorber, and the two membrane absorbers have the same composition; two membrane regenerators are provided in the regenerator, and the two membrane regenerators have the same composition.

[0092] The test results are shown in Table 1.

[0093] Example 8

[0094] The method in Example 5 is followed, except that the rich amine solution is fed into the regenerator after passing through a flash vessel, and the flash vessel is operated at a pressure of 0.6 MPa.

[0095] The test results are shown in Table 1.

[0096] Comparative Example 1

[0097] The method of Example 3 was followed, except that the lean amine solution contained 45 mass% MDEA, 5 mass% piperazine, and the remainder water.

[0098] The test results are shown in Table 1.

[0099] Comparative Example 2

[0100] The method of Example 3 was followed, except that the mass ratio of 2-amino-2-methyl-1,3-propanediol to 3,6-dihydroxymethylpiperazine in the activator was 1:4.6.

[0101] The test results are shown in Table 1.

[0102] Comparative Example 3

[0103] The method of Example 3 was followed, except that the mass ratio of 2-amino-2-methyl-1,3-propanediol to 3,6-dihydroxymethylpiperazine in the activator was 1:0.56.

[0104] The test results are shown in Table 1.

[0105] Comparative Example 4

[0106] The method of Example 1 was followed, except that the total amount of activator was 6.6 mass%, and the amount of sodium sulfite was 0.4 mass%.

[0107] The test results are shown in Table 1.

[0108] Comparative Example 5

[0109] The method of Example 1 was followed, except that an absorption tower and a regeneration tower were used instead of an absorber and a regenerator. The absorption tower had a diameter of 50 mm and a packing height of 1000 mm, and the regeneration tower had a diameter of 80 mm and a packing height of 1000 mm. The temperature at the top of the regeneration tower was 95-100°C, and the temperature at the bottom of the regeneration tower was 105-110°C.

[0110] The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113]

[0114] From the examples and comparative examples and Table 1, it can be seen that the decarburization solvent and decarburization method of the present application can improve the efficiency of decarburization absorption, can obtain purified gas meeting the purification index at a higher gas-liquid ratio, and can greatly reduce the regeneration energy consumption under the same treatment capacity. As can be seen from Examples 5-6, 8, the decarburization solvent and decarburization method of the present application can also effectively purify and absorb natural gas with high carbon content, and the CO2 content in the purified gas meets the Class 1 gas standard. As can be seen from Example 1 and Comparative Example 5, the decarburization system provided by the present application can further reduce the gas-liquid ratio compared with the traditional decarburization system, and improve the decarburization efficiency. As can be seen from Examples 1 and 7, the device in the present application can flexibly adjust the number of membrane absorbers in the absorber and membrane regenerators in the regenerator, which is conducive to greatly improving the gas-liquid ratio and thus improving the treatment load.

[0115] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for decarburization of a carbon-containing natural gas, characterized by, The method comprises the following steps: (1) contacting lean amine solution with carbon-containing natural gas in the presence of hydrophilic hollow fiber membrane to perform absorption, to obtain rich amine solution and decarbonized natural gas; (2) desorbing the rich amine solution in the presence of hydrophobic hollow fiber membrane to obtain regenerated lean amine solution which is returned to step (1); The CO2 content in the carbon-containing natural gas is 4-30 mol%.

2. The method of claim 1, wherein, The lean amine solution contains decarbonization solvent and water, the decarbonization solvent comprises main agent, activating agent and auxiliary agent; the main agent is N-methyldiethanolamine, the activating agent comprises primary amine and secondary amine, and the auxiliary agent is selected from at least one of potassium sorbate, sodium sorbate and sodium sulfite.

3. The method of claim 2, wherein, The primary amine is selected from hydroxyethyl diamine and / or 2-amino-2-methyl-1,3-propanediol; And / or, the secondary amine is selected from at least one of 2,5-dihydroxymethylpiperazine, 3,6-dihydroxymethylpiperazine, 2,3-dihydroxymethylpiperazine and 5,6-dihydroxymethylpiperazine.

4. The method of claim 2, wherein, The content of the main agent is 80-95% by mass, the content of the activating agent is 5-15% by mass, and the content of the auxiliary agent is 0.05-0.25% by mass, based on the total mass of the decarbonization solvent; And / or, the mass ratio of the primary amine to the secondary amine is 1:1-4.

5. The method of claim 4, wherein, The mass ratio of the primary amine to the secondary amine is 1:1.5-3.

6. The method of claim 2, wherein, The concentration of the decarbonization solvent is 45-55% by mass, based on the total mass of the lean amine solution.

7. The method of claim 1, wherein, The contact angle of the inner and outer surfaces of the hydrophilic hollow fiber membrane to water is not greater than 10 degrees, and the contact angle of the inner and outer surfaces of the hydrophobic hollow fiber membrane to water is not less than 150 degrees.

8. The method of claim 1, wherein, The outer diameter of the hydrophilic hollow fiber membrane or the hydrophobic hollow fiber membrane is 0.6-3 mm, and the inner diameter is 0.3-2.6 mm. And / or, the pore size of the hydrophilic hollow fiber membrane or the hydrophobic hollow fiber membrane is 0.05-3 μm, and the porosity is 40-85%; the pure water flux of the hydrophilic hollow fiber membrane or the hydrophobic hollow fiber membrane is 1000-5000 L / (m 2 ·h·bar), intensity ≥ 4 MPa.

9. The method of claim 1, wherein, The pressure of the carbon-containing natural gas is 2-8 MPa; And / or, the temperature of the lean amine solution is 40-75℃.

10. The method of claim 9, wherein, The pressure of the carbon-containing natural gas is 3-6 MPa; And / or, the temperature of the lean amine solution is 50-65℃.

11. The method of claim 1, wherein, The method further comprises temperature adjusting and / or flash evaporation of the rich amine solution in step (1) to obtain temperature-adjusted rich amine solution and flash vapor; And / or, the temperature of the temperature-adjusted rich amine solution is 65-85℃; And / or, the pressure of the flash evaporation is 0.5-0.8 MPa.

12. The method of claim 11, wherein, The temperature of the temperature-adjusted rich amine solution is 70-75℃.

13. The method of claim 1, wherein, The rich amine solution in step (2) is desorbed by vacuum suction; And / or, the vacuum degree of the vacuum suction is 10-50 kPa.

14. A decarbonization system of carbon-containing natural gas, characterized by, The decarbonization system comprises: a pretreatment unit, an absorber, a purified gas separator, a regenerator and a CO2 separator; wherein, The pretreatment unit is used for refining the carbon-containing natural gas to obtain refined carbon-containing natural gas; The absorber is used for contacting and absorbing the refined carbon-containing natural gas and lean amine solution, and the obtained decarbonized natural gas enters the purified gas separator, and the lean amine solution after absorbing CO2 obtains rich amine solution; The regenerator is used for desorbing CO2 from the rich amine solution, and the obtained regenerated lean amine solution is sent into the absorber, and the obtained CO2 enters the CO2 separator; The absorber comprises m membrane absorbers, and the membrane absorbers are provided with hydrophilic hollow fiber membranes; the regenerator comprises n membrane regenerators, and the membrane regenerators are provided with hydrophobic hollow fiber membranes; wherein m≥1, and n≥1.

15. The system of claim 14, wherein, The filling rate of the hydrophilic hollow fiber membranes in the membrane absorber is 60-95% by volume. And / or, the filling rate of the hydrophobic hollow fiber membranes in the membrane regenerator is 60-95% by volume.

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