A h2s concentration system

Abstract

The application discloses a H2S concentration system and belongs to the technical field of desulfurization equipment. The system comprises an acid gas classification absorption tower, rich-lean liquid heat exchangers, a carbon dioxide high-pressure regeneration tower, a gas-liquid heat exchanger, a hydrogen sulfide normal-pressure regeneration tower, a heater, an absorbent cooler, a regenerated gas cooler, a gas-liquid separator and a reflux pump. The acid gas classification absorption tower comprises a tower body and an inclined partition plate. The inclined partition plate is located in the tower body and divides the tower body into two cavities. The cavity above the inclined partition plate in the tower body is a carbon dioxide absorption cavity, and the cavity below the inclined partition plate in the tower body is a hydrogen sulfide absorption cavity. The combustible gas desulfurization regeneration system of the application realizes the process method of acid gas classification absorption classification treatment by improving the absorbent and combining with the acid gas classification absorption tower, and solves the problem of low H2S concentration of acid gas caused by CO2 co-absorption in the amine desulfurization.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of desulfurization equipment for natural gas, synthesis gas and refinery gas, in particular to an H2S concentration system. BACKGROUND

[0002] The amine method for removing H2S is widely used in the desulfurization process of natural gas, synthesis gas and refinery gas. However, the amine desulfurizer will absorb CO2 in the process gas while absorbing H2S, which leads to the decrease of H2S concentration in the regenerated acid gas, and the large amount of CO2 in the acid gas leads to the difficulty in the operation of the subsequent sulfur recovery process and the increase of investment. For the device with small H2S / CO2 in the process gas, two-stage absorption-two-stage regeneration process must be used to ensure that the H2S concentration in the regenerated acid gas meets the operation of CLAUS, or a large amount of gas is used for combustion to ensure the heat balance of the sulfur production device. Therefore, the existing H2S removal equipment by amine method needs to be improved to meet the requirements of energy saving and environmental protection. SUMMARY

[0003] The purpose of the present application is to provide an H2S concentration system which improves the H2S regeneration concentration in the acid gas.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is:

[0005] The application discloses an H2S concentration system, which comprises an acid gas classification absorption tower, a rich-lean liquid heat exchanger, a carbon dioxide high-pressure regeneration tower, a gas-liquid heat exchanger, a hydrogen sulfide normal-pressure regeneration tower, a heater, an absorbent cooler, a regeneration gas cooler, a gas-liquid separator and a reflux pump, wherein the acid gas classification absorption tower comprises a tower body and an inclined partition plate, the inclined partition plate is arranged in the tower body, the inclined partition plate divides the tower body into two cavities, the cavity above the inclined partition plate in the tower body is a carbon dioxide absorption cavity, the cavity below the inclined partition plate in the tower body is a hydrogen sulfide absorption cavity, the top of the tower body is provided with a treated gas discharge port, the bottom of the tower body is provided with a hydrogen sulfide rich liquid discharge port, a gas-liquid separation hydrophilic membrane is arranged in the hydrogen sulfide absorption cavity and close to the hydrogen sulfide rich liquid discharge port, the gas-liquid separation hydrophilic membrane is used for blocking gas and enabling the hydrogen sulfide rich liquid to pass through the gas-liquid separation hydrophilic membrane, a to-be-treated gas inlet is arranged on the side wall of the hydrogen sulfide absorption cavity and above the gas-liquid separation hydrophilic membrane, a plate-type micro-channel unit is arranged in the hydrogen sulfide absorption cavity and above the to-be-treated gas inlet, a hydrogen sulfide absorbent inlet is arranged on the side wall of the hydrogen sulfide absorption cavity and above the plate-type micro-channel unit, a desulfurization gas discharge port is arranged on the side wall of the hydrogen sulfide absorption cavity and close to the highest position of the plate surface of the inclined partition plate, a carbon dioxide rich liquid discharge port is arranged on the side wall of the carbon dioxide absorption cavity and close to the lowest position of the plate surface of the inclined partition plate, a desulfurization gas inlet is arranged on the side wall of the carbon dioxide absorption cavity and above the carbon dioxide rich liquid discharge port, the desulfurization gas inlet is communicated with the desulfurization gas discharge port through a desulfurization gas guide pipe, a baffle-type staggered plate group is arranged in the carbon dioxide absorption cavity and above the desulfurization gas inlet, a carbon dioxide absorbent inlet is arranged on the side wall of the carbon dioxide absorption cavity and above the baffle-type staggered plate group, a gas-liquid separation hydrophobic membrane is arranged in the carbon dioxide absorption cavity and above the carbon dioxide absorbent and below the treated gas discharge port, the hydrogen sulfide rich liquid in the hydrogen sulfide absorption cavity is discharged from the hydrogen sulfide rich liquid discharge port, under the action of a first conveying pump, the hydrogen sulfide rich liquid is heated by the gas-liquid heat exchanger and then flows into the hydrogen sulfide normal-pressure regeneration tower, the heater is used for heating the hydrogen sulfide rich liquid in the hydrogen sulfide normal-pressure regeneration tower, the high-temperature mixed gas of hydrogen sulfide regenerated from the hydrogen sulfide rich liquid in the hydrogen sulfide normal-pressure regeneration tower is discharged from the top of the hydrogen sulfide normal-pressure regeneration tower, the discharged high-temperature mixed gas flows through the gas-liquid heat exchanger to exchange heat with the hydrogen sulfide rich liquid, the heat-exchanged mixed gas is cooled by the regeneration gas cooler and then flows into the gas-liquid separator, the condensed liquid in the gas-liquid separator is refluxed into the hydrogen sulfide normal-pressure regeneration tower under the power of a reflux pump, and the hydrogen sulfide gas in the gas-liquid separator is discharged from the top of the gas-liquid separator.The high-temperature hydrogen sulfide absorbent after releasing hydrogen sulfide in the hydrogen sulfide atmospheric regeneration tower is discharged from the bottom of the hydrogen sulfide atmospheric regeneration tower, and flows through the rich-lean liquid heat exchanger to exchange heat with the carbon dioxide rich liquid. Under the action of the second delivery pump, the heat-exchanged hydrogen sulfide absorbent is cooled by the absorbent cooler and then flows into the hydrogen sulfide absorption cavity of the tower body through the hydrogen sulfide absorbent discharge port. The desulfurized gas in the hydrogen sulfide absorption cavity enters the carbon dioxide absorption cavity through the desulfurized gas discharge port, the desulfurized gas conduit and the desulfurized gas inlet in sequence. The carbon dioxide in the desulfurized gas is absorbed by the carbon dioxide absorbent in the carbon dioxide absorption cavity to form deacid gas. The deacid gas is separated into treated gas by the hydrophobic membrane gas-liquid separator. The treated gas is discharged from the treated gas discharge port at the top of the tower body. The carbon dioxide rich liquid in the carbon dioxide absorption cavity is discharged through the carbon dioxide rich liquid discharge port. Under the action of the third delivery pump, the carbon dioxide rich liquid is heated by the rich-lean liquid heat exchanger and then sent into the carbon dioxide high-pressure regeneration tower. The carbon dioxide gas regenerated from the carbon dioxide rich liquid in the carbon dioxide high-pressure regeneration tower is discharged from the top of the carbon dioxide high-pressure regeneration tower. The carbon dioxide absorbent after regeneration in the carbon dioxide high-pressure regeneration tower is discharged from the bottom of the carbon dioxide high-pressure regeneration tower. Under the action of the fourth delivery pump, the carbon dioxide absorbent flows into the carbon dioxide absorption cavity of the tower body through the carbon dioxide absorbent discharge port.

[0006] Further, the hydrogen sulfide absorbent is used to improve the absorption capacity for hydrogen sulfide gas and inhibit the absorption of carbon dioxide gas at the same time.

[0007] Further, the hydrogen sulfide absorbent comprises the following components in percentage by mass: 35-45% of main absorbent, 1-2% of complexing agent, and the balance of solvent. The main absorbent is modified tertiary amine, and the modified tertiary amine is trifluoromethyl modified tertiary amine (TF-MDEA).

[0008] Further, the trifluoromethyl modified tertiary amine (TF-MDEA) is a fluorine atom substitution modification of MDEA (methyl diethanolamine), in which the methyl group (-CH3) of MDEA (methyl diethanolamine) is replaced by a trifluoromethyl group (-CF3).

[0009] The mechanism of the modified tertiary amine is as follows: the strong electron-withdrawing effect (-I effect) of the trifluoromethyl group reduces the electron cloud density of the amine nitrogen, weakens the hydration catalytic ability of the stone and CO2 (inhibits CO2 absorption); but the strong acidity of H2S can still quickly undergo protonation reaction with the amine nitrogen (independent of catalysis), thus retaining the H2S absorption rate.

[0010] Further, the complexing agent is EDTA chelated Zn²⁺ ion (EDTA-Zn), and EDTA-Zn refers to a stable complex formed by ethylenediaminetetraacetic acid (EDTA) and zinc ion (Zn²⁺).

[0011] Chelation principle: EDTA is an important man-made organic polyacid complexing agent, also a six-coordinated chelating agent, each EDTA molecule can provide 4 oxygen atoms and 2 nitrogen atoms, can form 6 coordination bonds with a metal ion. Under the condition of high pH, complexation reaction occurs between zinc ions and EDTA, forming Zn(EDTA)²⁻ complex, which is a six-coordinated structure, zinc ions form coordination bonds with four carboxyl groups and two amino groups in EDTA molecules. The complex has high stability, which benefits from the multiple coordination bonds formed by EDTA and zinc ions and the ring structure, which makes the complex resistant to external interference and difficult to dissociate under certain conditions; it usually has good water solubility, which makes it uniformly dispersed in aqueous solution system, facilitating its application in various liquid environments.

[0012] Further, the solvent used is ethylene glycol dimethyl ether (DME). As an inert diluent, it can reduce the solubility of CO2 in the absorbent (the solubility of CO2 in DME is 1 / 3 of that in water), while not affecting the protonation reaction of H2S.

[0013] Further, the plate microchannel unit adopts a pull-out type modular plate microchannel, the tower body side wall is provided with a pull-out opening, the tower body inside and located on both sides of the pull-out opening is provided with a bearing guide rail, and the pull-out type modular plate microchannel is pulled out from the pull-out opening and supported on the bearing guide rail.

[0014] Further, the plate microchannel unit includes a square frame and a plurality of corrosion-resistant plates, the plurality of corrosion-resistant plates are stacked side by side in the square frame, the surface of the corrosion-resistant plate is provided with a row of vertical microchannels, the inner wall surface of the vertical microchannel is distributed with protrusions, the protrusions are used to break the gas-liquid boundary layer and increase the turbulence to improve the mass transfer coefficient, the outer side of the square frame is provided with a pull handle, and the two sides of the square frame are provided with rollers which are supported on the bearing guide rail and can roll along the bearing guide rail; the material of the corrosion-resistant plate is silicon carbide ceramic or PTFE material; the diameter of the vertical microchannel is 150-300 μm, and the length is 4-6 cm.

[0015] Further, the gas-liquid separation hydrophobic membrane adopts a pull-out type modular gas-liquid separation hydrophobic membrane, and the gas-liquid separation hydrophilic membrane adopts a pull-out type modular gas-liquid separation hydrophilic membrane, the tower body side wall is provided with an upper pull-out opening and a lower pull-out opening, the tower body inside and located on both sides of the upper pull-out opening is provided with an upper bearing guide rail, the tower body inside and located on both sides of the lower pull-out opening is provided with a lower bearing guide rail, the pull-out type modular gas-liquid separation hydrophobic membrane is pulled out from the upper pull-out opening and supported on the upper bearing guide rail, and the pull-out type modular gas-liquid separation hydrophilic membrane is pulled out from the lower pull-out opening and supported on the lower bearing guide rail.

[0016] Further, the gas-liquid separation hydrophobic membrane comprises a hydrophobic membrane body made of PTFE, and the surface of the hydrophobic membrane body is distributed with membrane holes with an inner diameter of 0.25-0.35 microns; the gas-liquid separation hydrophilic membrane comprises a hydrophilic membrane body made of PVDF, and the surface of the hydrophilic membrane body is distributed with membrane holes with an inner diameter of 0.55-0.65 microns.

[0017] The present application has the following beneficial effects:

[0018] The combustible gas desulfurization regeneration system of the present application realizes the process method of classified absorption and treatment of acid gas by improving the absorbent and combining with the acid gas classified absorption tower, and solves the problem of low H2S concentration of acid gas caused by CO2 co-absorption in the amine desulfurization method.

[0019] The selectivity coefficient (alpha) of the hydrogen sulfide absorbent in the present application to H2S is improved from 3.5 of the conventional MDEA to 12.6, greatly improving the selectivity to H2S; the co-absorption amount of the hydrogen sulfide absorbent to CO2 is reduced by more than 70% compared with the traditional MDEA method, greatly improving the regeneration concentration of H2S in acid gas. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Fig. 1 is a structural schematic diagram of the regeneration system of the present application;

[0021] Figure 2 Fig. 2 is a structural schematic diagram of the acid gas classified absorption tower shown in Fig. 1; Figure 1

[0022] Fig. 3 is a side view of the acid gas classified absorption tower shown in Fig. 2; Figure 3 Figure 2 Fig. 4 is a structural schematic diagram of the plate micro-channel unit shown in Fig. 1;

[0023] Figure 4 Figure 2 Fig. 5 is a structural schematic diagram of the corrosion-resistant plate shown in Fig. 1;

[0024] Figure 5 Fig. 6 is a structural schematic diagram of the corrosion-resistant plate shown in Fig. 1; Figure 4

[0025] Fig. 7 is a top view of the corrosion-resistant plate shown in Fig. 1. Figure 6 Figure 5

[0026] ​​​​In the diagram: 1. Acid gas classification and absorption tower; 2. Rich and lean liquid heat exchanger; 3. High-pressure carbon dioxide regeneration tower; 4. Gas-liquid heat exchanger; 5. Hydrogen sulfide atmospheric pressure regeneration tower; 6. Heater; 7. Absorbent cooler; 8. Regenerated gas cooler; 9. Gas-liquid separator; 10. Reflux pump; 11. Tower body; 12. Inclined partition plate; 13. Carbon dioxide absorption chamber; 14. Hydrogen sulfide absorption chamber; 15. Treated gas outlet; 16. Hydrogen sulfide rich liquid outlet; 17. Gas-liquid separation hydrophilic membrane; 18. Untreated gas inlet; 19. Plate microchannel unit; 20. Hydrogen sulfide absorbent inlet; 21. 1. Desulfurization gas outlet; 22. Carbon dioxide rich liquid outlet; 23. Desulfurization gas inlet; 24. Desulfurization gas conduit; 25. Baffle-type staggered plate assembly; 26. Carbon dioxide absorbent outlet; 27. Gas-liquid separation hydrophobic membrane; 28. First transfer pump; 29. ​​Second transfer pump; 30. Third transfer pump; 31. Upper pull-out port; 32. Lower pull-out port; 33. Upper load-bearing guide rail; 34. Lower load-bearing guide rail; 35. Fourth transfer pump; 36. Pull-out port; 37. Load-bearing guide rail; 38. Square frame; 39. Corrosion-resistant plate; 40. Vertical microchannel; 41. Protrusion; 42. Pull-out handle; 43. Roller. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper surface," "lower surface," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "forward," "reverse," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] like Figure 1 , Figure 2 , Figure 3As shown, a H2S concentration system includes an acid gas classification absorption tower 1, a rich-lean liquid heat exchanger 2, a carbon dioxide high-pressure regeneration tower 3, a gas-liquid heat exchanger 4, a hydrogen sulfide atmospheric regeneration tower 5, a heater 6, an absorbent cooler 7, a regenerated gas cooler 8, a gas-liquid separator 9 and a reflux pump 10. The acid gas classification absorption tower 1 includes a tower body 11 and an inclined partition plate 12 located in the tower body 11. The inclined partition plate 12 separates the tower body 11 into two cavities. The cavity above the inclined partition plate 12 is a carbon dioxide absorption cavity 13. The cavity below the inclined partition plate 12 is a hydrogen sulfide absorption cavity 14. The top of the tower body 11 is provided with a treated gas discharge outlet 15. The bottom of the tower body 11 is provided with a hydrogen sulfide rich liquid discharge outlet 16. The hydrogen sulfide absorption cavity 14 is provided with a gas-liquid separation hydrophilic membrane 17 near the hydrogen sulfide rich liquid discharge outlet 16. The gas-liquid separation hydrophilic membrane 17 prevents gas from being discharged from the hydrogen sulfide rich liquid discharge outlet 16. The hydrogen sulfide rich liquid can pass through the gas-liquid separation hydrophilic membrane 17 to be smoothly discharged from the hydrogen sulfide rich liquid discharge outlet 16, thereby preventing the carbon dioxide from reacting with the liquid for a long time. The side wall of the hydrogen sulfide absorption cavity 14 is provided with a treated gas discharge inlet 18 above the gas-liquid separation hydrophilic membrane 17. The hydrogen sulfide absorption cavity 14 is provided with a plate-type microchannel unit 19 above the treated gas discharge inlet 18. The side wall of the hydrogen sulfide absorption cavity 14 is provided with a hydrogen sulfide absorbent discharge inlet 20 above the plate-type microchannel unit 19. The side wall of the hydrogen sulfide absorption cavity 14 is provided with a desulfurized gas discharge outlet 21 near the highest part of the plate surface of the inclined partition plate 12. The side wall of the carbon dioxide absorption cavity 13 is provided with a carbon dioxide rich liquid discharge outlet 22 near the lowest part of the plate surface of the inclined partition plate 12. The side wall of the carbon dioxide absorption cavity 13 is provided with a desulfurized gas inlet 23 above the carbon dioxide rich liquid discharge outlet 22. The desulfurized gas inlet 23 communicates with the desulfurized gas discharge outlet 21 through a desulfurized gas guide pipe 24. The carbon dioxide absorption cavity 13 is provided with a baffle-type staggered plate group 25 above the desulfurized gas inlet 23. The side wall of the carbon dioxide absorption cavity 13 is provided with a carbon dioxide absorbent discharge inlet 26 above the baffle-type staggered plate group 25. The carbon dioxide absorption cavity 13 is provided with a gas-liquid separation hydrophobic membrane 27 above the carbon dioxide absorbent discharge inlet 26. The gas-liquid separation hydrophobic membrane 27 is below the treated gas discharge outlet 15.The hydrogen sulfide rich liquid in the hydrogen sulfide absorption cavity 14 is discharged from the hydrogen sulfide rich liquid discharge port 16, and under the action of the first delivery pump 28, the hydrogen sulfide rich liquid is heated by the gas-liquid heat exchanger 4 and then flows into the hydrogen sulfide atmospheric pressure regeneration tower 5, the heater 6 is used to heat the hydrogen sulfide rich liquid in the hydrogen sulfide atmospheric pressure regeneration tower 5, the high-temperature mixed gas in which hydrogen sulfide is regenerated from the hydrogen sulfide rich liquid in the hydrogen sulfide atmospheric pressure regeneration tower 5 is discharged from the top of the hydrogen sulfide atmospheric pressure regeneration tower 5, and after the discharge, the high-temperature mixed gas flows through the gas-liquid heat exchanger 4 and exchanges heat with the hydrogen sulfide rich liquid, and after the heat exchange, the mixed gas is cooled by the regeneration gas cooler 8 and then flows into the gas-liquid separator 9, the condensed liquid in the gas-liquid separator 9 flows back to the hydrogen sulfide atmospheric pressure regeneration tower 5 under the power of the reflux pump 10, and the hydrogen sulfide gas in the gas-liquid separator 9 is discharged from the top of the gas-liquid separator 9; the high-temperature hydrogen sulfide absorbent after releasing hydrogen sulfide in the hydrogen sulfide atmospheric pressure regeneration tower 5 is discharged from the bottom of the hydrogen sulfide atmospheric pressure regeneration tower 5, and the discharged high-temperature hydrogen sulfide absorbent flows through the rich-lean liquid heat exchanger 2 and exchanges heat with the carbon dioxide rich liquid, under the action of the second delivery pump 29, the heat-exchanged hydrogen sulfide absorbent is cooled by the absorbent cooler 7 and then flows back to the hydrogen sulfide absorption cavity 14 of the tower body 11 through the hydrogen sulfide absorbent discharge port 20, the desulfurized gas in the hydrogen sulfide absorption cavity 14 enters the carbon dioxide absorption cavity 13 in turn through the desulfurized gas discharge port 21, the desulfurized gas conduit 24 and the desulfurized gas inlet 23, the carbon dioxide in the desulfurized gas is absorbed by the carbon dioxide absorbent in the carbon dioxide absorption cavity 13 to form deacid gas, the deacid gas is separated by the gas-liquid separation hydrophobic membrane 27 to form treated gas, and the treated gas is discharged from the treated gas discharge port 15 at the top of the tower body 11; the carbon dioxide rich liquid in the carbon dioxide absorption cavity 13 is discharged from the carbon dioxide rich liquid discharge port 22, under the action of the third delivery pump 30, the carbon dioxide rich liquid is heated by the rich-lean liquid heat exchanger 2 and then sent into the carbon dioxide high-pressure regeneration tower 3, the carbon dioxide gas regenerated from the carbon dioxide rich liquid in the carbon dioxide high-pressure regeneration tower 3 is discharged from the top of the carbon dioxide high-pressure regeneration tower 3, and the carbon dioxide absorbent after the regeneration of carbon dioxide in the carbon dioxide high-pressure regeneration tower 3 is discharged from the bottom of the carbon dioxide high-pressure regeneration tower 3, under the action of the fourth delivery pump 35, the carbon dioxide absorbent flows back to the carbon dioxide absorption cavity 13 of the tower body 11 from the carbon dioxide absorbent discharge port 26.

[0030] The gas-liquid separation hydrophobic membrane 27 adopts a pull-out type modular gas-liquid separation hydrophobic membrane, and the gas-liquid separation hydrophilic membrane 17 adopts a pull-out type modular gas-liquid separation hydrophilic membrane. The side wall of the tower body 11 is provided with an upper pull-out opening 31 and a lower pull-out opening 32. The tower body 11 is internally provided with upper bearing guide rails 33 on both sides of the upper pull-out opening 31. The tower body 11 is internally provided with lower bearing guide rails 34 on both sides of the lower pull-out opening 32. The pull-out type modular gas-liquid separation hydrophobic membrane is pulled into the upper bearing guide rails 33 from the upper pull-out opening 31. The pull-out type modular gas-liquid separation hydrophilic membrane is pulled into the lower bearing guide rails 34 from the lower pull-out opening 32. The pull-out type modular design is adopted to facilitate the installation and replacement of the gas-liquid separation hydrophobic membrane 27 and the gas-liquid separation hydrophilic membrane 17, thereby greatly simplifying the later maintenance process.

[0031] The gas-liquid separation hydrophobic membrane 27 includes a hydrophobic membrane body made of PTFE. The surface of the hydrophobic membrane body is distributed with membrane holes with an inner diameter of 0.25-0.35 μm. The gas-liquid separation hydrophilic membrane 17 includes a hydrophilic membrane body made of PVDF. The surface of the hydrophilic membrane body is distributed with membrane holes with an inner diameter of 0.55-0.65 μm.

[0032] As shown in Figure 2 , the plate type microchannel unit 19 adopts a pull-out type modular plate type microchannel. The side wall of the tower body 11 is provided with a pull-out opening 36. The tower body 11 is internally provided with bearing guide rails 37 on both sides of the pull-out opening 36. The pull-out type modular plate type microchannel is pulled into the bearing guide rails 37 from the pull-out opening 36.

[0033] Specifically, as shown in Figure 4 , Figure 5 , Figure 6 , the plate type microchannel unit 19 includes a square frame 38 and a plurality of corrosion-resistant plates 39. The plurality of corrosion-resistant plates 39 are arranged side by side in the square frame 38. The surface of the corrosion-resistant plate 39 is provided with a row of vertical microchannels 40. The inner wall surface of the vertical microchannel 40 is distributed with protrusions 41. The protrusions 41 are used to break the gas-liquid boundary layer and increase the turbulence to improve the mass transfer coefficient. The outer side of the square frame 38 is provided with a pull handle 42. The two sides of the bottom of the square frame 38 are provided with rollers 43. The rollers 43 are supported on the bearing guide rails 37 and can roll along the bearing guide rails 37. The material of the corrosion-resistant plate 39 adopts silicon carbide ceramic or PTFE material. The diameter of the vertical microchannel is 150-300 μm, and the length is 4-6 cm.

[0034] The hydrogen sulfide absorbent is improved in this embodiment to improve the absorption capacity for hydrogen sulfide gas and simultaneously inhibit the absorption of carbon dioxide gas.

[0035] Specifically, the hydrogen sulfide absorber includes the following components by mass percentage: 35-45% of the main absorber, 1-2% of the complexing agent, and the balance of the solvent, wherein the main absorber is a modified tertiary amine, and the modified tertiary amine is a trifluoromethyl-modified tertiary amine (TF-MDEA).

[0036] The preparation method of the trifluoromethyl-modified tertiary amine (TF-MDEA) is as follows:

[0037] I. Reaction raw materials and reagents

[0038] • Raw material: A tertiary amine precursor with potential reaction sites can be selected, such as diphenylamine, N-ethyl aniline, N-methyl p-toluidine, etc.

[0039] • Trifluoromethylation reagent: such as (phen)Cu III (CF3)3, which is an effective trifluoromethylation reagent that can provide trifluoromethyl radicals.

[0040] • Base: such as anhydrous potassium carbonate, used to neutralize acidic substances produced in the reaction and promote the progress of the reaction.

[0041] • Solvent: such as N,N-dimethylformamide (DMF), used as a reaction medium to dissolve reactants and reagents.

[0042] II. Reaction parameters and conditions

[0043] • Reaction temperature: usually carried out at a higher temperature, usually 100°C, to promote the progress of the reaction.

[0044] • Reaction time: depending on the specific reaction and raw materials, the reaction time may vary, but generally takes about ten hours, such as 17 hours.

[0045] • Reaction atmosphere: carried out under the protection of inert gas (such as nitrogen) to avoid the influence of oxygen and water in the air on the reaction.

[0046] • Raw material ratio: adjust the ratio of raw materials according to the structure of the target product and the reaction mechanism. For example, the molar ratio of trifluoromethylation reagent, tertiary amine precursor and base is 1.3:1:2 or similar.

[0047] III. Reaction steps

[0048] 1. Prepare the reaction tube: place a stirrer in a 25mL Schlenk tube, then add an appropriate amount of trifluoromethylation reagent, base and solvent.

[0049] 2. Seal and vacuum: seal the tube opening with a rubber plug and sealing film, then perform three repeated vacuum and nitrogen filling operations to exclude air from the tube.

[0050] 3. Add tertiary amine precursor: Mix the tertiary amine precursor with a small amount of solvent, then slowly add it to the reaction tube with a syringe.

[0051] 4. Stir the reaction: Place the reaction tube in an oil bath and stir at the set temperature for a certain period of time.

[0052] 5. Post-processing: After the reaction is complete, cool the reaction tube to room temperature. Then add an appropriate amount of dichloromethane to dilute and filter the reaction solution. Add a small amount of silica gel to dry column chromatography to obtain the target product.

[0053] The trifluoromethyl-modified tertiary amine (TF-MDEA) is a modification of MDEA (methyl diethanolamine) by replacing the methyl group (-CH3) with a trifluoromethyl group (-CF3). The mechanism of modifying tertiary amine in this application: the strong electron-withdrawing effect of trifluoromethyl (-I effect) reduces the electron cloud density of amine nitrogen, weakening the hydration catalytic ability of the material and CO2 (inhibiting CO2 absorption); but the strong acidity of H2S can still quickly protonate with amine nitrogen, which does not depend on catalysis, thus improving the H2S absorption rate.

[0054] The complexing agent in this embodiment is EDTA-chelated Zn² + ion (EDTA-Zn), EDTA-Zn refers to a stable complex formed by ethylenediaminetetraacetic acid (EDTA) and zinc ion (Zn²⁺). Chelation principle: EDTA is an important artificial organic polyacid complexing agent and a six-coordinated chelating agent. Each EDTA molecule can provide 4 oxygen atoms and 2 nitrogen atoms, which can form 6 coordination bonds with a metal ion. Under conditions of high pH, complexation occurs between zinc ions and EDTA, forming a Zn(EDTA)²⁻ complex, which is a six-coordinated structure. The zinc ion forms coordination bonds with four carboxyl groups and two amino groups in the EDTA molecule. This complex has high stability, which is due to the multiple coordination bonds and ring structure formed by EDTA and zinc ions. This structure makes the complex resistant to external interference and difficult to dissociate under certain conditions; it usually has good water solubility, which allows it to disperse uniformly in aqueous solution systems, making it easy to apply in various liquid environments.

[0055] Trifluoromethyl-modified tertiary amine (TF-MDEA) is a basic substance, 35-45% of the main absorbent, which can adjust the pH value of the hydrogen sulfide absorbent to the range of 8-10, and adjust the temperature of the complexation reaction to 60-80°C. The reversible complexation reaction is as follows: EDTA-Zn 2+ + H2S ⇌ EDTA-Zn-SH − + H + .

[0056] The solvent of the present application is ethylene glycol dimethyl ether (DME). It acts as an inert diluent, which can reduce the solubility of CO2 in the absorbent (the solubility of CO2 in DME is 1 / 3 of that in water), while not affecting the protonation reaction of H2S.

[0057] Experimental data: Through comparison by experiment, the selectivity coefficient (a) of H2S is improved from 3.5 of conventional MDEA to 12.6, greatly improving the selectivity of H2S; the co-absorption amount of hydrogen sulfide absorbent of the present application to CO2 is reduced by more than 70% compared with the traditional MDEA method, greatly improving the regeneration concentration of H2S in acid gas.

[0058] Working principle: To solve the core problem of low H2S concentration in acid gas caused by CO2 co-absorption in amine desulfurization, it is necessary to break through from two dimensions of enhancing H2S absorption selectivity and optimizing acid gas separation efficiency.

[0059] The essential difference between amine absorption of H2S and CO2 is:

[0060] • H2S: can directly react with the basic site (-NH - / -N - ) of amine (no intermediate step);

[0061] • CO2: needs to be hydrated as H2CO3 first, and the reaction with tertiary amine (such as MDEA) needs hydration catalysis, characterized by slow rate and low equilibrium constant.

[0062] Therefore, the inventive concept of the present application is as follows:

[0063] Firstly, the absorbent is improved to achieve the following functions: 1. Strengthening the "targeted absorption" of H2S: through molecular modification and complexation, the selectivity of amine to H2S is improved; 2. Inhibiting the "ineffective absorption" of CO2: through solvent regulation or kinetic hindrance, the reaction of CO2 with amine is reduced.

[0064] Secondly, the absorption tower is improved, and an acid gas classification type absorption tower is designed. The acid gas classification type absorption tower utilizes the weaker binding force of H2S and amine to preferentially absorb H2S gas and then absorb CO2 gas, realizing the acid gas classification treatment of H2S gas and CO2 gas in natural gas, so as to solve the problem of low H2S concentration in acid gas caused by CO2 co-absorption in amine desulfurization.

[0065] For the improvement of the absorbent, the absorbent of the present application is composed of main absorbent (modified tertiary amine) + complexing agent (metal chelate) + solvent (inert diluent), and the core is to improve the selectivity of H2S through "molecular recognition + complexation enhancement". The complexing agent (metal chelate) is to use EDTA-Zn 2+Reversible complexation reaction with H2S to improve the selective binding ability of amines to H2S.

[0066] Finally, the present application uses a plate micro-channel unit in the hydrogen sulfide absorption cavity 14, the vertical micro-channel in the plate micro-channel unit has a diameter of 150-300 μm and a length of 4-6 cm. The design aims to shorten the contact time of natural gas (gas to be treated) and the absorbent. Since H2S reacts quickly and CO2 reacts slowly, the mechanism is that the short diffusion path length of the micro-channel is only 4-6 cm, thereby controlling the gas-liquid contact time within 50 ms. Within 50 ms, H2S has been completely absorbed by the absorbent, while the reaction time of CO2 needs 100 ms. CO2 is "trapped" in the gas phase due to the insufficient reaction time. On the basis of the plate micro-channel unit, the gas flow speed of the natural gas is controlled, thereby controlling the gas-liquid contact time within 50 ms, so that CO2 cannot react and be absorbed in the hydrogen sulfide absorption cavity 14. The CO2 in the gas phase is sent to the carbon dioxide absorption cavity 13 for absorption treatment, thereby achieving the purpose of classified treatment of acid gas.

[0067] In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. An H2S concentration system, characterized in that: The system includes an acid gas separation and absorption tower, a rich and lean liquid heat exchanger, a high-pressure carbon dioxide regeneration tower, a gas-liquid heat exchanger, a hydrogen sulfide atmospheric pressure regeneration tower, a heater, an absorbent cooler, a regenerated gas cooler, a gas-liquid separator, and a reflux pump. The acid gas separation and absorption tower comprises a tower body and an inclined partition plate located within the tower body. The inclined partition plate divides the tower body into upper and lower cavities. The cavity above the inclined partition plate is the carbon dioxide absorption cavity, and the cavity below the inclined partition plate is the hydrogen sulfide absorption cavity. The top of the tower body has a treated gas outlet, and the bottom of the tower body has a hydrogen sulfide rich liquid outlet. The hydrogen sulfide absorption cavity contains… A hydrophilic gas-liquid separation membrane is installed near the hydrogen sulfide-rich liquid outlet. This membrane blocks gas while allowing the hydrogen sulfide-rich liquid to pass through. A gas outlet for the untreated gas is located on the side wall of the hydrogen sulfide absorption chamber, above the hydrophilic gas-liquid separation membrane. A plate-type microchannel unit is located inside the hydrogen sulfide absorption chamber, above the gas outlet for the untreated gas. A hydrogen sulfide absorbent outlet is located on the side wall of the hydrogen sulfide absorption chamber, above the plate-type microchannel unit. A desulfurization gas outlet is located on the side wall of the hydrogen sulfide absorption chamber, near the highest point of the inclined partition plate. A carbon dioxide absorption chamber outlet is located on the side wall, near the lowest point of the inclined partition plate. A carbon dioxide-rich liquid outlet is located at the position of the absorption chamber. A desulfurization gas inlet is located on the side wall of the carbon dioxide absorption chamber, above the carbon dioxide-rich liquid outlet. The desulfurization gas inlet is connected to the desulfurization gas outlet via a desulfurization gas conduit. A baffle-type staggered plate assembly is located inside the carbon dioxide absorption chamber, above the desulfurization gas inlet. A carbon dioxide absorbent outlet is located on the side wall of the carbon dioxide absorption chamber, above the carbon dioxide absorbent. A gas-liquid separation hydrophobic membrane is located inside the carbon dioxide absorption chamber, above the carbon dioxide absorbent, and is positioned below the treated gas outlet. The hydrogen sulfide-rich liquid in the hydrogen sulfide absorption chamber is discharged from the hydrogen sulfide-rich liquid outlet. Under the action of the first delivery pump, the hydrogen sulfide-rich liquid is heated by the gas-liquid heat exchanger and flows into the hydrogen sulfide atmospheric pressure regeneration tower. The heater is used to heat the hydrogen sulfide-rich liquid in the hydrogen sulfide atmospheric pressure regeneration tower. The high-temperature mixed gas that regenerates hydrogen sulfide in the hydrogen sulfide-rich liquid in the hydrogen sulfide atmospheric pressure regeneration tower is discharged from the top of the hydrogen sulfide atmospheric pressure regeneration tower. The discharged high-temperature mixed gas flows through the gas-liquid heat exchanger and exchanges heat with the hydrogen sulfide-rich liquid. The mixed gas after heat exchange is cooled by the regeneration gas cooler and flows into the gas-liquid separator. The condensate in the gas-liquid separator is returned to the hydrogen sulfide atmospheric pressure regeneration tower under the power of the reflux pump. The hydrogen sulfide gas in the gas-liquid separator is discharged from the top of the gas-liquid separator.The high-temperature hydrogen sulfide absorbent, after releasing hydrogen sulfide in the atmospheric pressure hydrogen sulfide regeneration tower, is discharged from the bottom of the tower. The discharged high-temperature absorbent flows through a rich-lean liquid heat exchanger and exchanges heat with a carbon dioxide-rich liquid. Under the action of a second delivery pump, the heat-exchanged absorbent is cooled by an absorbent cooler and then flows back into the hydrogen sulfide absorption chamber of the tower body through the absorbent outlet. The desulfurized gas in the absorption chamber enters the carbon dioxide absorption chamber sequentially through the desulfurized gas outlet, desulfurized gas conduit, and desulfurized gas inlet. The carbon dioxide in the desulfurized gas is absorbed by the carbon dioxide absorbent in the absorption chamber, forming deacidified gas. The deacidified gas undergoes gas-liquid separation via a hydrophobic membrane. The treated gas is then formed and discharged from the treated gas outlet at the top of the tower. The carbon dioxide-rich liquid in the carbon dioxide absorption chamber is discharged through the carbon dioxide-rich liquid outlet. Under the action of the third transfer pump, the carbon dioxide-rich liquid is heated by the rich-lean liquid heat exchanger and sent into the carbon dioxide high-pressure regeneration tower. The carbon dioxide gas regenerated by the carbon dioxide-rich liquid in the carbon dioxide high-pressure regeneration tower is discharged from the top of the carbon dioxide high-pressure regeneration tower. The carbon dioxide absorbent after carbon dioxide regeneration in the carbon dioxide high-pressure regeneration tower is discharged from the bottom of the carbon dioxide high-pressure regeneration tower. Under the action of the fourth transfer pump, the carbon dioxide absorbent flows back into the carbon dioxide absorption chamber of the tower from the carbon dioxide absorbent outlet. The hydrogen sulfide absorbent is used to improve the absorption capacity of hydrogen sulfide gas and simultaneously inhibit the absorption of carbon dioxide gas. The hydrogen sulfide absorbent comprises the following components by mass percentage: 35-45% main absorbent, 1-2% complexing agent, and the balance being solvent. The main absorbent is a modified tertiary amine, which is a trifluoromethyl-modified tertiary amine. The trifluoromethyl-modified tertiary amine is a fluorine atom substitution modification of MDEA (methyldiethanolamine), replacing the methyl group (-CH3) of MDEA (methyldiethanolamine) with a trifluoromethyl group (-CF3).

2. The H2S concentration system according to claim 1, characterized in that: The complexing agent used is EDTA-chelated Zn²⁺ ions (EDTA-Zn), where EDTA-Zn refers to a stable complex formed by ethylenediaminetetraacetic acid (EDTA) and zinc ions (Zn²⁺).

3. The H2S concentration system according to claim 2, characterized in that: The solvent used is ethylene glycol dimethyl ether (DME).

4. The H2S concentration system according to claim 1, characterized in that: The plate-type microchannel unit adopts a pull-out modular plate-type microchannel. The tower body has a pull-out opening on its side wall. The tower body is equipped with load-bearing guide rails on both sides of the pull-out opening. The pull-out modular plate-type microchannel extends from the pull-out opening and is supported on the load-bearing guide rails.

5. The H2S concentration system according to claim 4, characterized in that: The plate-type microchannel unit includes a square frame and multiple corrosion-resistant plates stacked side-by-side in the square frame. Each corrosion-resistant plate has a row of vertical microchannels on its surface, and protrusions are distributed on the inner wall of each vertical microchannel to disrupt the gas-liquid boundary layer and increase turbulence. A pull-out handle is located on the outer side of the square frame, and rollers are located at the bottom of both sides of the square frame. These rollers are supported on a support rail and can roll along the support rail. The corrosion-resistant plates are made of silicon carbide ceramic or PTFE material. The diameter of each vertical microchannel is 150-300 μm, and its length is 4-6 cm.

6. The H2S concentration system according to claim 1, characterized in that: The gas-liquid separation hydrophobic membrane is a pull-out modular gas-liquid separation hydrophobic membrane, and the gas-liquid separation hydrophilic membrane is a pull-out modular gas-liquid separation hydrophilic membrane. The tower body has an upper pull-out port and a lower pull-out port on its side wall. The tower body has upper support guide rails on both sides of the upper pull-out port and lower support guide rails on both sides of the lower pull-out port. The pull-out modular gas-liquid separation hydrophobic membrane extends from the upper pull-out port and is supported on the upper support guide rail, and the pull-out modular gas-liquid separation hydrophilic membrane extends from the lower pull-out port and is supported on the lower support guide rail.

7. The H2S concentration system according to claim 6, characterized in that: The gas-liquid separation hydrophobic membrane includes a hydrophobic membrane body made of PTFE material, with membrane pores distributed on its surface, the inner diameter of which is 0.25-0.35 μm; the gas-liquid separation hydrophilic membrane includes a hydrophilic membrane body made of PVDF material, with membrane pores distributed on its surface, the inner diameter of which is 0.55-0.65 μm.

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