Method and device for multi-stage absorption and recovery of light hydrocarbons

Abstract

The invention belongs to the field of oil refining and chemical engineering, and relates to a method and a device for recovering light hydrocarbon by multistage absorption. Compared with the prior art, the method has the following advantages: an atmospheric and vacuum distillation unit and a hydrocracking unit are not required to be independently provided with an absorption stabilizing system, so that the problem of secondary separation of key components is reduced; an H2 / C1 coarse separation facility is arranged in front of the absorption tower, so that the H2 partial pressure in the raw material gas is reduced, the reduction of the circulating volume, the absorption pressure or the absorption temperature of a C4 absorbent is facilitated, and meanwhile, the size of the absorption tower is reduced; crude hydrocarbon subjected to desulfurization and mercaptan removal and crude hydrocarbon condensed by a cooler at an outlet of a third raw material gas compressor are sent to a first absorption section of the multi-stage absorption tower, C3-C5 components contained in the raw materials are used as absorbents, the amount of circulating C4 is reduced, and energy consumption is reduced; the multi-stage absorption tower is arranged, and the absorbent enters different positions of the multi-stage absorption tower according to different contents of C3 and C4 in the absorbent, so that the absorption effect is improved.

Description

Technical Field

[0001] The present invention belongs to the field of oil refining and chemical industry, and more specifically, relates to a method and device for multi-stage absorption recovery of light hydrocarbons, and more specifically to a device and method for recovering saturated light hydrocarbons from the atmospheric and vacuum distillation, hydrocracking, hydrofining, aromatics reforming and other equipment in a refinery that is rich in saturated light hydrocarbons. Background Art

[0002] Saturated light hydrocarbons in refineries primarily come from top gas and mixed naphtha from atmospheric and vacuum units, rich gas and crude hydrocarbons from the top of the hydrogen sulfide stripping towers in various hydrocracking units, and fuel gas from various hydrotreating units. The recovery of light hydrocarbons from these materials is primarily achieved through atmospheric and vacuum light hydrocarbon recovery and various hydrocracking absorption and stabilization systems to recover liquefied gas components such as C3 and C4. C2 is used as fuel gas in dry gas. With the development of integrated refining and chemical processing, further recovery of C2 from dry gas to provide lightweight ethylene feed for ethylene units has gained attention. Chemical refineries with ethylene units typically construct new C2 recovery units to recover C2 from dry gas and send the ethane-rich gas to the cracking furnaces in the ethylene units as cracking feed, reducing external ethylene feed purchases and further improving the economic efficiency of the refinery.

[0003] The conventional process setup involves first recovering liquefied gas through absorption stabilization, and then recovering the C2 component through a C2 recovery unit that uses shallow cold oil absorption technology. Since the C2 recovery unit uses C4 as an absorbent to absorb the C2 component in the absorption tower, the C4 component and the C2 component are separated in advance in the upstream absorption and stabilization system. The C2 recovery unit needs to supplement with C4 as an absorbent to recover C2, thus creating a secondary separation of the C2 / C4 components. Meanwhile, for the hydrocracking unit, the C4 component and the naphtha component are separated in the debutanizer / hydrogen sulfide stripper. To achieve the separation of the C2 and C3 components in the absorption and stabilization system, naphtha is used as an absorbent and mixed again in the absorption tower. To obtain the liquefied gas product, they need to be separated again in the stabilization tower, which is the secondary separation of the C4 component and the naphtha component. The secondary separation of key components increases separation energy consumption and the number of equipment required. Since C2, C3 and C4 components can all be used as ethylene cracking materials, and C4 is also needed as an absorbent to recover C2 components, the necessity of setting up an absorption stabilization system is greatly reduced for chemical refineries that do not have C3 and C4 deep processing and comprehensive utilization equipment.

[0004] C4 absorbs C2 and above in the absorption tower. A higher partial pressure of the target component in the gaseous feedstock reduces the absorption pressure, lowering the pressure at the outlet of the feed gas compressor and reducing the amount of circulating absorbent, and vice versa. In currently implemented C2 recovery process designs, the feed gas enters the absorption tower directly, where it comes into countercurrent contact with the C4 absorbent. H2 separation facilities are not considered before the absorption tower to reduce H2 content. This greatly increases the difficulty of recovering C2 from materials with high H2 content.

[0005] Usually, carbon dioxide and above components are recovered by using one absorbent in the absorption tower and controlling the circulation volume to achieve a certain recovery rate. There is no multi-stage absorption according to the different absorbent components to increase the recovery effect.

[0006] The present invention is proposed in order to realize the full recovery of saturated light hydrocarbons in all units of the plant, provide lightweight ethylene materials for the ethylene unit, optimize the component separation sequence, simplify the separation process, and reduce investment and energy consumption. Summary of the Invention

[0007] The purpose of the present invention is to provide a light hydrocarbon separation device and method with a simple process flow and mild operating conditions. This method can achieve efficient separation and recovery of C2, C3 and C4 components. At the same time, the recovered dry gas contains fewer impurities, and hydrogen can be directly recovered by pressure swing adsorption.

[0008] In order to achieve the above object, a first aspect of the present invention provides a method for recovering light hydrocarbons by multi-stage absorption, the recovery method comprising the following steps:

[0009] (1) Gas phase pressurization I: The hydrotreated sulfur-rich gas is compressed and pressurized by the first feed gas compressor, cooled by the cooler I, and separated by the liquid separator I. The sulfur-rich and heavy component-rich gas is obtained at the top of the tank, and the sulfur-rich and heavy component crude hydrocarbons are obtained at the bottom of the tank;

[0010] (2) Naphtha stabilization in the whole plant: mixed naphtha, sulfur-containing and heavy component rich gas and sulfur-containing and heavy component crude hydrocarbon are sent to the stabilization tower for stabilization treatment. Stabilized naphtha is obtained at the bottom of the tower and divided into two parts. One part is used as the mixed naphtha product, and the other part is sent to the top of the reabsorption section of the multi-stage absorption tower as a reabsorbent. The top gas phase of the stabilization tower is obtained at the top of the tower, which is condensed in the condenser and sent to the stabilization tower reflux tank to obtain the rich gas at the top of the stabilization tower reflux tank and the liquid phase at the bottom of the stabilization tower reflux tank;

[0011] (3) Gas phase pressure boosting II: The rich gas at the top of the stabilization tower reflux tank is sent to the second raw gas compressor for compression and pressure boosting, cooled in cooler II, and separated in separator II to obtain the rich gas at the top of separator II and the liquid phase at the bottom of separator II;

[0012] (4) Rich gas desulfurization: The rich gas at the top of the separator tank II passes through the superheater and is sent to the gas phase desulfurization tower, where it comes into contact with the lean amine liquid in reverse flow to remove hydrogen sulfide and obtain sulfur-free rich gas;

[0013] (5) Crude hydrocarbon desulfurization: The liquid phase at the bottom of the stabilization tower reflux tank is pressurized by the stabilization tower reflux pump and then separated into two parts. One part enters the desulfurization and demercaptan tower, and the liquid phase at the bottom of the separator tank II is pumped out by the crude hydrocarbon pump II and sent to the desulfurization and demercaptan tower to remove hydrogen sulfide and mercaptan, thereby obtaining sulfur-free crude hydrocarbons. The crude hydrocarbons are cooled by the shallow cooler II and then sent to the top of the first absorption section of the multi-stage absorption tower as a first-stage absorbent.

[0014] (6) H2 / C1 coarse separation: The sulfur-free rich gas is subjected to H1 / C1 coarse separation to obtain a H2-rich gas phase after coarse separation and a rich gas after H2 / C1 coarse separation;

[0015] (7) Gas-liquid equilibrium: After the H2 / C1 coarse separation, the rich gas is cooled by the shallow cooler I and then enters the separator IV for separation, obtaining the gas phase at the top of the separator IV and the liquid phase at the bottom of the separator IV;

[0016] (8) C3 / C4 separation: the liquid phase at the bottom of the separator IV is sent to the demethanizer, and the gas phase at the top of the tower is mixed with the hydrofined sulfur-rich gas to undergo (1) gas phase pressurization I treatment. The liquid phase at the bottom of the demethanizer is sent to the deethanizer, and the ethane-rich gas product is obtained at the top of the tower. The liquid phase at the bottom of the tower is divided into two parts, one of which is sent to the top of the third absorption section of the multi-stage absorption tower as the third stage absorbent, and the other part is sent to the depropanizer. A part of the liquid phase at the top of the tower is sent to the top of the second absorption section of the multi-stage absorption tower as the second stage absorbent, and the remaining part is the liquid propane product. The liquid phase at the bottom of the tower is divided into two parts, one of which is used as a mixed C4 product, and the other part is sent to the top of the fourth absorption section of the multi-stage absorption tower as the fourth stage absorbent;

[0017] (9) Multi-stage absorption: The gas phase at the top of the separator IV tank is sent to the bottom of the first absorption section of the multi-stage absorption tower, and then passes through the first absorption section, the second absorption section, the third absorption section, the fourth absorption section and the reabsorption section for multi-stage absorption. Methane hydrogen dry gas is obtained at the top of the multi-stage absorption tower, and the liquid phase at the bottom of the reabsorption section is sent to the stabilization tower for (2) naphtha stabilization treatment of the whole plant.

[0018] In the present invention, the absorbents of the multi-stage absorption tower are, from bottom to top, crude hydrocarbons after desulfurization, C3-rich hydrocarbons at the top of the depropanizer, hydrocarbons at the bottom of the deethanizer, C4-rich hydrocarbons at the bottom of the depropanizer, and stabilized naphtha at the bottom of the stabilization tower. By adjusting the absorbent ratio of each absorption stage, the recovery of C2 and above components can be maximized without the need for additional absorbent supplementation outside the system.

[0019] According to the present invention, preferably, the H2 / C1 coarse separation includes one of the following two methods:

[0020] Method 1:

[0021] Membrane separation: The sulfur-free rich gas is purified into hydrogen through a membrane separation unit to obtain purified hydrogen and rich gas after H2 / C1 coarse separation. The rich gas after H2 / C1 coarse separation is sent to a gas-liquid equilibrium; the pressure loss of the membrane separation tail gas is 0.2-0.5 MPag;

[0022] Method 2:

[0023] Pressure swing adsorption: The sulfur-free rich gas passes through the pressure swing adsorption unit to obtain hydrogen and rich gas after H2 / C1 coarse separation. The rich gas after H2 / C1 coarse separation is pressurized by the pressure swing adsorption tail gas compressor and sent to the gas-liquid balance; the rich gas after H2 / C1 coarse separation is pressurized to 2.5~4.5MPag by the pressure swing adsorption tail gas compressor.

[0024] In the present invention, the H2 recovery rate is 60% to 85%. The purified hydrogen is sent to the downstream device through a hydrogen compressor for further hydrogen recovery, and the hydrogen obtained by the pressure swing adsorption unit is sent to the hydrogen pipeline network.

[0025] According to the present invention, preferably, the operating temperature of the top of the stabilization tower is 40-60° C., and the operating pressure is 0.8-1.2 MPaG.

[0026] According to the present invention, preferably, the temperature of the reflux tank of the stabilization tower is 30-45°C.

[0027] According to the present invention, preferably, the operating temperature of the gas phase desulfurization tower is 40-45° C., and the operating pressure is 2.5-4.5 MPaG.

[0028] According to the present invention, preferably, the operating temperature of the crude hydrocarbon desulfurization tower is 35-45° C., and the operating pressure is 3.0-5.0 MPaG.

[0029] According to the present invention, preferably, the outlet pressure of the first raw gas compressor is 2.5-4.5 MPaG, the crude hydrocarbon containing sulfur and heavy components is sent to the middle part of the stabilization tower, and the rich gas containing sulfur and heavy components is sent to the upper part of the stabilization tower.

[0030] In the present invention, the liquid phase at the bottom of the separator tank I is sent to the middle of the stabilization tower, and the gas phase at the top is sent to the upper part of the stabilization tower for stabilization, thereby separating the C5 and above components in the raw materials, reducing the impact on the desulfurization of the rich gas, and reducing the risk of foaming.

[0031] According to the present invention, preferably, the outlet pressure of the second raw gas compressor is 2.5-4.5 MPaG.

[0032] According to the present invention, preferably, another part of the liquid phase at the bottom of the stabilization tower reflux tank is sent to the upper part of the stabilization tower.

[0033] According to the present invention, preferably, the temperature of the shallow cooler I is 15-20° C., and the pressure is 2.0-4.0 MPag.

[0034] According to the present invention, preferably, the pressure of the multi-stage absorption tower is 2.0-4.0 MPag.

[0035] According to the present invention, preferably, the top pressure of the demethanizer is 1.0-1.5 MPag.

[0036] According to the present invention, preferably, the top pressure of the deethanizer is 1.5-2.5 MPag.

[0037] According to the present invention, preferably, the top pressure of the depropanizer is 1.4-2.0 MPag.

[0038] According to the present invention, preferably, the liquid phase at the bottom of the multi-stage absorption tower is mixed with the rich gas after the H2 / C1 coarse separation to perform (7) gas-liquid equilibrium treatment.

[0039] In the present invention, the liquid hydrocarbons at the bottom of the multi-stage absorption tower are sent to the gas-liquid balance, cooled together with the feed gas, further absorb C2 and above components in the gas phase, and then enter the liquid separator.

[0040] According to the present invention, preferably, the ratio of the total amount of absorbent in each section of the multi-stage absorption tower to the amount of gas phase entering the tower is controlled at 2-6.

[0041] A second aspect of the present invention provides a multi-stage absorption and light hydrocarbon recovery device, which includes: a mixed naphtha feed pipeline, a hydrorefining sulfur-rich gas feed pipeline, a stabilization tower, a first raw gas compressor, a cooler I, a liquid separator I, a second raw gas compressor, a cooler II, a liquid separator II, a crude hydrocarbon pump II, a superheater, a gas phase desulfurization tower, a desulfurization and demercaptan unit, an H2 / Cl coarse separation unit, a shallow cooler I, a shallow cooler II, a liquid separator IV, a multi-stage absorption tower, a demethanizer, a deethanizer, and a depropanizer; the multi-stage absorption tower includes, from bottom to top, a first absorption section, a second absorption section, a third absorption section, a fourth absorption section, and a reabsorption section;

[0042] Among them, the hydrofining sulfur-rich gas feed pipeline is connected to the first raw gas compressor, the cooler 1 and the separator 1 in sequence, and the separator 1 is provided with a separator 1 tank top discharge pipeline and a separator 1 tank bottom discharge pipeline;

[0043] The mixed naphtha feed pipeline, the separator tank 1 top discharge pipeline and the separator tank 1 bottom discharge pipeline are connected to the stabilization tower, the stabilization tower is provided with a stabilization tower top discharge pipeline and a stabilization tower bottom discharge pipeline, the stabilization tower bottom discharge pipeline is divided into two branches, one of which is used as a mixed petroleum naphtha product discharge pipeline, and the other is connected to the reabsorption section of the multi-stage absorption tower. The upper part of the stabilization tower is also provided with a condenser and a stabilization tower reflux tank, the stabilization tower top discharge pipeline is connected to the condenser and the stabilization tower reflux tank in sequence, and the stabilization tower reflux tank is provided with a stabilization tower reflux tank top discharge pipeline and a stabilization tower reflux tank bottom discharge pipeline;

[0044] The top discharge pipeline of the stabilization tower reflux tank is connected to the second raw gas compressor, cooler II and separator II in sequence, and the separator II is provided with a top discharge pipeline of the separator II tank and a bottom discharge pipeline of the separator II tank;

[0045] The discharge pipeline from the top of the separator tank II is connected to the superheater and the gas phase desulfurization tower in sequence, and the gas phase desulfurization tower is provided with a gas phase desulfurization tower discharge pipeline;

[0046] The discharging pipeline at the bottom of the stabilization tower reflux tank is connected to the stabilization tower reflux pump and is divided into two branches, one of which is connected to the desulfurization and sweetening tower. The discharging pipeline at the bottom of the separator tank II is connected to the crude hydrocarbon pump II and the desulfurization and sweetening tower in sequence. The desulfurization and sweetening tower is provided with a desulfurization and sweetening tower discharging pipeline.

[0047] The gas phase desulfurization tower discharge pipeline is connected to the H2 / C1 coarse separation unit, and the H2 / C1 coarse separation unit is provided with a hydrogen discharge pipeline and a H2 / C1 coarse separation rich gas discharge pipeline, and the H2 / C1 coarse separation rich gas discharge pipeline is sequentially connected to the shallow cooler I and the separator tank IV, and the separator tank IV is provided with a separator tank IV tank top discharge pipeline and a separator tank IV tank bottom discharge pipeline;

[0048] The bottom discharge pipeline of the liquid separator IV is connected to the demethanizer in sequence, and the demethanizer is provided with a demethanizer top discharge pipeline and a demethanizer bottom discharge pipeline, and the demethanizer top discharge pipeline is connected to the first raw gas compressor after merging with the hydrorefining sulfur-rich gas feed pipeline; the demethanizer bottom discharge pipeline is connected to the deethanizer, and the deethanizer is provided with a deethanizer top discharge pipeline and a deethanizer bottom discharge pipeline, and the deethanizer bottom discharge pipeline is divided into two branches, one of which is connected to the third absorption section of the multi-stage absorption tower, and the other is connected to the depropanizer; the depropanizer is provided with a depropanizer top discharge pipeline and a depropanizer bottom discharge pipeline, the depropanizer top discharge pipeline is connected to the second absorption section of the multi-stage absorption tower, and the depropanizer bottom discharge pipeline is divided into two branches, one of which is used as a mixed carbon four product discharge pipeline, and the other is connected to the fourth absorption section of the multi-stage absorption tower;

[0049] The top discharge pipeline of the liquid separator IV is connected to the bottom of the first absorption section of the multi-stage absorption tower. The multi-stage absorption tower is provided with a top discharge pipeline of the multi-stage absorption tower, a bottom discharge pipeline of the reabsorption section of the multi-stage absorption tower and a bottom discharge pipeline of the multi-stage absorption tower. The bottom discharge pipeline of the reabsorption section of the multi-stage absorption tower merges with the mixed naphtha feed pipeline.

[0050] In the present invention, an intermediate reboiler is arranged in the middle of the deethanizer, and a bottom reboiler is arranged at the bottom of the tower. The intermediate reboiler and the bottom reboiler use the high-temperature liquid hydrocarbon at the bottom of the depropanizer as heat source and do not require steam.

[0051] According to the present invention, preferably, the H2 / C1 coarse separation unit includes the following two connection modes:

[0052] Method 1:

[0053] The gas phase desulfurization tower discharge pipeline is connected to the membrane separation unit, and the membrane separation unit is provided with a membrane separation unit hydrogen discharge pipeline and a membrane separation unit H2 / C1 coarse separation rich gas discharge pipeline, and the membrane separation unit H2 / C1 coarse separation rich gas discharge pipeline is connected to the shallow cooler I;

[0054] Method 2:

[0055] The gas phase desulfurization tower discharge pipeline is connected to the pressure swing adsorption unit, and the pressure swing adsorption unit is provided with a pressure swing adsorption unit hydrogen discharge pipeline and a pressure swing adsorption unit H2 / C1 coarse separation rich gas discharge pipeline. The pressure swing adsorption unit H2 / C1 coarse separation rich gas discharge pipeline is connected to the pressure swing adsorption tail gas compressor and the shallow cooler I in sequence.

[0056] According to the present invention, preferably, the discharge line from the top of the liquid separator tank 1 is connected to the upper part of the stabilization tower, and the discharge line from the bottom of the liquid separator tank 1 is connected to the middle part of the stabilization tower.

[0057] According to the present invention, preferably, another stabilization tower reflux tank bottom discharge pipeline is connected to the upper part of the stabilization tower;

[0058] According to the present invention, preferably, the bottom discharge pipeline of the multi-stage absorption tower merges with the discharge pipeline of the gas phase desulfurization tower.

[0059] Compared with the prior art, the present invention has the following advantages:

[0060] (1) In the present invention, the naphtha-containing liquid phase after the atmospheric and vacuum unit, each hydrorefining unit and the sulfur-containing gas phase are pressurized and cooled is centralized and stabilized, thereby reducing the content of heavy components in the sulfur-containing rich gas and reducing the foaming risk of the gas phase desulfurization tower.

[0061] (2) The present invention no longer requires the atmospheric and vacuum unit and the hydrocracking unit to be equipped with a separate absorption stabilization system, thereby reducing the problem of secondary separation of key components.

[0062] (3) In the present invention, a H2 / C1 coarse separation facility is set in front of the absorption tower, which reduces the H2 partial pressure in the raw gas, is beneficial to reducing the circulation amount of the C4 absorbent, the absorption pressure or the absorption temperature, and at the same time reduces the size of the absorption tower.

[0063] (4) In the present invention, the crude hydrocarbons after desulfurization and demercaptanization and the crude hydrocarbons condensed by the cooler at the outlet of the third raw gas compressor are sent to the first absorption section of the multi-stage absorption tower. The C3 to C5 components contained in the raw materials themselves are used as absorbents, which reduces the amount of circulating C4 and helps reduce energy consumption.

[0064] (5) Set up a multi-stage absorption tower. According to the different contents of C3 and C4 in the absorbent, they enter different positions of the multi-stage absorption tower to improve the absorption effect.

[0065] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0067] Figure 1 The process flow chart of multi-stage absorption and recovery of light hydrocarbons in Example 1 of the present invention is shown.

[0068] Figure 2 The process flow chart of multi-stage absorption and recovery of light hydrocarbons in Example 2 of the present invention is shown.

[0069] Description of reference numerals:

[0070] 1. Stabilization tower; 2. Stabilization tower reflux tank; 3. Stabilization tower reflux pump; 4. Second feed gas compressor; 5. Cooler II; 6. Separator II; 7. Crude hydrocarbon pump II; 8. Superheater; 9. Gas phase desulfurization tower; 10. First feed gas compressor; 11. Cooler I; 12. Separator I; 17. Shallow cooler I; 18. Shallow cooler II; 19. Desulfurization and demercaptan tower; 20. Membrane separation unit or pressure swing adsorption unit; 22. Pressure swing adsorption tail gas compressor; 23. Separator IV; 24. Multi-stage absorption tower; 25. Demethanizer; 26. Depropanizer; 27. Deethanizer

[0071] S-1, mixed naphtha; S-2, sulfur-containing and heavy component rich gas; S-3, sulfur-containing and heavy component crude hydrocarbons; S-4, hydrotreated sulfur-containing rich gas; S-6, sulfur-free rich gas; S-7, first-stage absorbent; S-8, rich gas after H2 / C1 crude separation; S-9, fourth-stage absorbent; S-10, mixed C4 product; S-11, ethane-rich gas product; S-12, methane hydrogen dry gas; S-13, reabsorbent; S-14, mixed naphtha product; S-15, second-stage absorbent; S-16, third-stage absorbent. DETAILED DESCRIPTION

[0072] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0073] Example 1

[0074] The multi-stage absorption and light hydrocarbon recovery device includes: a mixed naphtha feed pipeline, a hydrorefining sulfur-rich gas feed pipeline, a stabilization tower 1, a first raw gas compressor 10, a cooler I11, a separator I12, a second raw gas compressor 4, a cooler II 5, a separator II 6, a crude hydrocarbon pump II 7, a superheater 8, a gas phase desulfurization tower 9, a desulfurization and demercaptan unit 19, a membrane separation unit 20, a shallow cooler I17, a shallow cooler II 18, a separator IV 23, a multi-stage absorption tower 24, a demethanizer 25, a deethanizer 27 and a depropanizer 26; the multi-stage absorption tower 24 includes, from bottom to top, a first absorption section, a second absorption section, a third absorption section, a fourth absorption section and a reabsorption section.

[0075] Among them, the hydrofining sulfur-rich gas feed pipeline is connected to the first raw gas compressor 10, the cooler 111 and the separator 112 in sequence, and the separator 1 is provided with a separator 1 tank top discharge pipeline and a separator 1 tank bottom discharge pipeline; the separator 1 tank top discharge pipeline is connected to the upper part of the stabilization tower, and the separator 1 tank bottom discharge pipeline is connected to the middle part of the stabilization tower;

[0076] The mixed naphtha feed pipeline is connected to the lower part of the stabilization tower, and the stabilization tower is provided with a stabilization tower top discharge pipeline and a stabilization tower bottom discharge pipeline. The stabilization tower bottom discharge pipeline is divided into two branches, one of which is used as a mixed petroleum naphtha product discharge pipeline, and the other is connected to the reabsorption section of the multi-stage absorption tower. The upper part of the stabilization tower is also provided with a condenser and a stabilization tower reflux tank. The stabilization tower top discharge pipeline is sequentially connected to the condenser and the stabilization tower reflux tank 2. The stabilization tower reflux tank is provided with a stabilization tower reflux tank top discharge pipeline and a stabilization tower reflux tank bottom discharge pipeline;

[0077] The top discharge pipeline of the stabilization tower reflux tank is connected to the second raw gas compressor 4, the cooler II 5 and the separator II 6 in sequence. The separator II is provided with a top discharge pipeline of the separator II and a bottom discharge pipeline of the separator II.

[0078] The discharge pipeline from the top of the separator tank II is connected to the superheater and the gas phase desulfurization tower in sequence, and the gas phase desulfurization tower is provided with a gas phase desulfurization tower discharge pipeline;

[0079] The discharging pipeline at the bottom of the stabilization tower reflux tank is connected to the stabilization tower reflux pump and is divided into two branches, one of which is connected to the desulfurization and sweetening tower. The discharging pipeline at the bottom of the separator tank II is connected to the crude hydrocarbon pump II and the desulfurization and sweetening tower in sequence. The desulfurization and sweetening tower is provided with a desulfurization and sweetening tower discharging pipeline.

[0080] The gas phase desulfurization tower discharge pipeline is connected to the membrane separation unit, and the membrane separation unit is provided with a hydrogen discharge pipeline and a H2 / C1 coarse separation rich gas discharge pipeline, and the H2 / C1 coarse separation rich gas discharge pipeline is sequentially connected to the shallow cooler I17 and the separator tank IV 23, and the separator tank IV is provided with a separator tank IV tank top discharge pipeline and a separator tank IV tank bottom discharge pipeline;

[0081] The bottom discharge pipeline of the liquid separator IV is connected to the demethanizer in sequence, and the demethanizer is provided with a demethanizer top discharge pipeline and a demethanizer bottom discharge pipeline, and the demethanizer top discharge pipeline is connected to the first raw gas compressor after merging with the hydrorefining sulfur-rich gas feed pipeline; the demethanizer bottom discharge pipeline is connected to the deethanizer, and the deethanizer is provided with a deethanizer top discharge pipeline and a deethanizer bottom discharge pipeline, and the deethanizer bottom discharge pipeline is divided into two branches, one of which is connected to the third absorption section of the multi-stage absorption tower, and the other is connected to the depropanizer; the depropanizer is provided with a depropanizer top discharge pipeline and a depropanizer bottom discharge pipeline, the depropanizer top discharge pipeline is connected to the second absorption section of the multi-stage absorption tower, and the depropanizer bottom discharge pipeline is divided into two branches, one of which is used as a mixed carbon four product discharge pipeline, and the other is connected to the fourth absorption section of the multi-stage absorption tower;

[0082] The top discharge pipeline of the liquid separator IV is connected to the bottom of the first absorption section of the multi-stage absorption tower. The multi-stage absorption tower is provided with a top discharge pipeline of the multi-stage absorption tower, a bottom discharge pipeline of the reabsorption section of the multi-stage absorption tower and a bottom discharge pipeline of the multi-stage absorption tower. The bottom discharge pipeline of the reabsorption section of the multi-stage absorption tower merges with the mixed naphtha feed pipeline, and the bottom discharge pipeline of the multi-stage absorption tower merges with the discharge pipeline of the gas phase desulfurization tower.

[0083] The above device is used to carry out multi-stage absorption and recovery of light hydrocarbons. The process flow chart is as follows: Figure 1 As shown:

[0084] (1) Gas phase pressurization I: The hydrotreated sulfur-rich gas is compressed and pressurized by the first raw gas compressor, cooled by cooler I, and separated by liquid separator I. The sulfur-rich and heavy component-rich gas is obtained at the top of the tank, and the sulfur-rich and heavy component crude hydrocarbons are obtained at the bottom of the tank; the outlet pressure of the first raw gas compressor is 3.0 MPag.

[0085] (2) Naphtha stabilization in the whole plant: mixed naphtha, sulfur-containing and heavy component rich gas and sulfur-containing and heavy component crude hydrocarbons are sent to the stabilization tower for stabilization treatment. Stabilized naphtha is obtained at the bottom of the tower and divided into two parts, one of which is used as a mixed naphtha product and the other is sent to the top of the reabsorption section of the multi-stage absorption tower as a reabsorbent. The top gas phase of the stabilization tower is obtained at the top of the tower, which is condensed in the condenser and sent to the stabilization tower reflux tank to obtain the rich gas at the top of the stabilization tower reflux tank and the liquid phase at the bottom of the stabilization tower reflux tank; the operating pressure of the stabilization tower is 1.0 MPag, the top temperature is 45°C, and the outlet pressure of the stabilization tower reflux pump is 3.5 MPag.

[0086] (3) Gas phase pressure boosting II: The rich gas at the top of the reflux tank of the stabilization tower is sent to the second raw gas compressor for compression and pressure boosting, cooled in cooler II and separated in separator II to obtain the rich gas at the top of separator II and the liquid phase at the bottom of separator II; the outlet pressure of the first raw gas compressor is 2.5-4.5MPag.

[0087] (4) Rich gas desulfurization: The rich gas at the top of separator II passes through the superheater and is sent to the gas phase desulfurization tower, where it contacts the lean amine liquid in reverse to remove hydrogen sulfide and obtain sulfur-free rich gas. The superheater 8 controls the superheat at 3-5°C to avoid the formation of condensate and foaming in the gas phase desulfurization tower. The operating pressure of the gas phase desulfurization tower is 2.5-4.5 MPaG.

[0088] (5) Crude hydrocarbon desulfurization: The liquid phase at the bottom of the stabilization tower reflux tank is pressurized by the stabilization tower reflux pump and then divided into two parts. One part enters the desulfurization and demercaptan tower. The liquid phase at the bottom of the separator tank II is pumped out by the crude hydrocarbon pump II and sent to the desulfurization and demercaptan tower. After removing hydrogen sulfide and mercaptans, sulfur-free crude hydrocarbons are obtained. After cooling in the shallow cooler II, they are sent to the top of the first absorption section of the multi-stage absorption tower as a first-stage absorbent. The operating temperature of the desulfurization and demercaptan tower is 35-45°C and the operating pressure is 3.0-5.0 MPaG. The crude hydrocarbons are sent to the first absorption section of the multi-stage absorption tower, using the C3-C4 components in the crude hydrocarbon feedstock as absorbents to initially absorb the C2 component, which can reduce the amount of circulating absorbent.

[0089] (6) H2 / C1 coarse separation: Sulfur-free rich gas undergoes H1 / C1 coarse separation to obtain a crude H2-rich gas phase and a H2 / C1 coarse-separated rich gas. The hydrogen partial pressure in the feed gas after H2 / C1 coarse separation is significantly reduced, while the partial pressures of key components are increased, which helps reduce the absorption dose. The H2 recovery rate is 60% to 85%, and the membrane separation tail gas pressure loss is 0.2 to 0.5 MPag.

[0090] (7) Gas-liquid balance: After the H2 / C1 coarse separation, the rich gas is cooled by the shallow cooler I and then enters the separator IV for separation, obtaining the gas phase at the top of the separator IV and the liquid phase at the bottom of the separator IV; the liquid phase hydrocarbons at the bottom of the multi-stage absorption tower are mixed with the raw gas and cooled, and the C2 component can be further absorbed in this process, thereby reducing the packing height of the multi-stage absorption tower and the circulating absorption dose. The outlet temperature of the shallow cooler I is 15°C.

[0091] (8) C3 / C4 separation: The liquid phase at the bottom of separator IV is sent to the demethanizer, and the gas phase at the top of the tower is mixed with the hydrofined sulfur-rich gas to undergo (1) gas phase pressure boosting I treatment. The liquid phase at the bottom of the demethanizer is sent to the deethanizer, and the ethane-rich gas product is obtained at the top of the tower. The liquid phase at the bottom of the tower is divided into two parts, one of which is sent to the top of the third absorption section of the multi-stage absorption tower as the third stage absorbent, and the other part is sent to the depropanizer. The gas phase at the top of the tower is sent to the top of the second absorption section of the multi-stage absorption tower as the second stage absorbent. The liquid phase at the bottom of the tower is divided into two parts, one of which is used as a mixed C4 product, and the other part is sent to the top of the fourth absorption section of the multi-stage absorption tower as the fourth stage absorbent; the operating pressure of the demethanizer is 0.5~1.0MPag, the deethanizer is 1.5-2.5MPag, and the operating pressure of the depropanizer is 1.5~2.5MPag.

[0092] (9) Multi-stage absorption: The gas phase at the top of the liquid separator IV is sent to the bottom of the first absorption section of the multi-stage absorption tower, and then passes through the first absorption section, the second absorption section, the third absorption section, the fourth absorption section and the reabsorption section for multi-stage absorption. Methane hydrogen dry gas is obtained at the top of the multi-stage absorption tower, and the liquid phase at the bottom of the reabsorption section is sent to the stabilization tower for (2) whole-plant naphtha stabilization treatment. According to the different C3 and C4 content and composition of each absorbent, they enter different positions of the multi-stage absorption tower respectively. According to the similarity and compatibility of the components, the absorption characteristics of each section of the absorbent are maximized to achieve the purpose of reducing the absorption dose. The operating pressure of the multi-stage absorption tower 24 is 2.5-4.0MPag, and 1-3 mid-stage refluxes can be set. The ratio of the total amount of absorbent in each section of the multi-stage absorption tower to the amount of gas phase entering the tower is controlled at 2-6.

[0093] The compositions and properties of the products of dry gas, ethane-rich gas, propane-rich gas, and mixed C4 separated from light hydrocarbons by the above method are shown in Tables 1 to 3. The recovery rate of the C2 component is 98.5%, and the recovery rates of the C3 and C4 components are 99%.

[0094] Table 1 Dry gas properties

[0095] Temperature, °C 40 Pressure, MPag 3.0 composition v％ <![CDATA[H2]]> 34.47027778 CO 0.0125 <![CDATA[N2]]> 1.3896 <![CDATA[CH4]]> 63.587644 <![CDATA[C2H6]]> 0.0382 <![CDATA[NC4H 10 ]]> 0.0158 <![CDATA[C5+]]> 0.4805

[0096] Table 2 Properties of ethane-rich gas

[0097] Temperature, °C 43 Pressure, MPag 1.45 composition v％ <![CDATA[CH4]]> 1.28024 <![CDATA[C2H6]]> 63.08637255 <![CDATA[C3H8]]> 35.08708 <![CDATA[H2O]]> 0.069444 C4+ 0.546808

[0098] Table 3 Properties of mixed C4

[0099] Temperature, °C 40 Pressure, MPag 1.0 composition wt% <![CDATA[C3H8]]> 0.714439 <![CDATA[IC4H 10 ]]> 33.40663366 <![CDATA[NC4H 10 ]]> 63.40138614 <![CDATA[H2O]]> 2.045247525 <![CDATA[C5+]]> 0.495544554

[0100] Example 2

[0101] The only difference between the device of this embodiment and that of Example 1 is that the H2 / C1 coarse separation unit 20 is a pressure swing adsorption unit, which is provided with a pressure swing adsorption unit hydrogen discharge pipeline and a pressure swing adsorption unit H2 / C1 coarse separation rich gas discharge pipeline, and the pressure swing adsorption unit H2 / C1 coarse separation rich gas discharge pipeline is connected in sequence to the pressure swing adsorption tail gas compressor 22 and the shallow cooler I17.

[0102] Use Figure 2 The process flow chart shown is for oil and gas desulfurization and light hydrocarbon recovery:

[0103] The only difference between this embodiment and embodiment 1 is that:

[0104] (7) H2 / C1 coarse fraction:

[0105] Pressure swing adsorption: The sulfur-free rich gas passes through the pressure swing adsorption unit to obtain hydrogen and rich gas after H2 / C1 coarse separation. The rich gas after H2 / C1 coarse separation is pressurized by the pressure swing adsorption tail gas compressor and sent to the gas-liquid balance; the rich gas after H2 / C1 coarse separation is pressurized to 2.5~4.5MPag by the pressure swing adsorption tail gas compressor.

[0106] The product properties are consistent with those in Tables 1 to 3 of Example 1.

[0107] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for recovering light hydrocarbons by multi-stage absorption, characterized in that: The recycling method comprises the following steps: (1) Gas phase pressurization I: The hydrotreated sulfur-rich gas is compressed and pressurized by the first feed gas compressor, cooled by the cooler I, and separated by the liquid separator I. The sulfur-rich and heavy component-rich gas is obtained at the top of the tank, and the sulfur-rich and heavy component crude hydrocarbons are obtained at the bottom of the tank; (2) Naphtha stabilization in the whole plant: mixed naphtha, sulfur-containing and heavy component rich gas and sulfur-containing and heavy component crude hydrocarbon are sent to the stabilization tower for stabilization treatment. Stabilized naphtha is obtained at the bottom of the tower and divided into two parts. One part is used as the mixed naphtha product, and the other part is sent to the top of the reabsorption section of the multi-stage absorption tower as a reabsorbent. The top gas phase of the stabilization tower is obtained at the top of the tower, which is condensed in the condenser and sent to the stabilization tower reflux tank to obtain the rich gas at the top of the stabilization tower reflux tank and the liquid phase at the bottom of the stabilization tower reflux tank; (3) Gas phase pressure boosting II: The rich gas at the top of the stabilization tower reflux tank is sent to the second raw gas compressor for compression and pressure boosting, cooled in cooler II, and separated in separator II to obtain the rich gas at the top of separator II and the liquid phase at the bottom of separator II; (4) Rich gas desulfurization: The rich gas at the top of the separator tank II passes through the superheater and is sent to the gas phase desulfurization tower, where it comes into contact with the lean amine liquid in reverse flow to remove hydrogen sulfide and obtain sulfur-free rich gas; (5) Crude hydrocarbon desulfurization: The liquid phase at the bottom of the stabilization tower reflux tank is pressurized by the stabilization tower reflux pump and then separated into two parts. One part enters the desulfurization and demercaptan tower, and the liquid phase at the bottom of the separator tank II is pumped out by the crude hydrocarbon pump II and sent to the desulfurization and demercaptan tower to remove hydrogen sulfide and mercaptan, thereby obtaining sulfur-free crude hydrocarbons. The crude hydrocarbons are cooled by the shallow cooler II and then sent to the top of the first absorption section of the multi-stage absorption tower as a first-stage absorbent. (6) H2 / C1 coarse separation: The sulfur-free rich gas is subjected to H1 / C1 coarse separation to obtain a H2-rich gas phase after coarse separation and a rich gas after H2 / C1 coarse separation; (7) Gas-liquid equilibrium: After the H2 / C1 coarse separation, the rich gas is cooled by the shallow cooler I and then enters the separator IV for separation, obtaining the gas phase at the top of the separator IV and the liquid phase at the bottom of the separator IV; (8) C3 / C4 separation: the liquid phase at the bottom of the separator IV is sent to the demethanizer, and the gas phase at the top of the tower is mixed with the hydrofined sulfur-rich gas to undergo (1) gas phase pressurization I treatment. The liquid phase at the bottom of the demethanizer is sent to the deethanizer, and the ethane-rich gas product is obtained at the top of the tower. The liquid phase at the bottom of the tower is divided into two parts, one of which is sent to the top of the third absorption section of the multi-stage absorption tower as the third stage absorbent, and the other part is sent to the depropanizer. A part of the liquid phase at the top of the tower is sent to the top of the second absorption section of the multi-stage absorption tower as the second stage absorbent, and the remaining part is used as the liquid phase propane product. The liquid phase at the bottom of the tower is divided into two parts, one of which is used as a mixed C4 product, and the other part is sent to the top of the fourth absorption section of the multi-stage absorption tower as the fourth stage absorbent; (9) Multi-stage absorption: The gas phase at the top of the separator IV tank is sent to the bottom of the first absorption section of the multi-stage absorption tower, and then passes through the first absorption section, the second absorption section, the third absorption section, the fourth absorption section and the reabsorption section for multi-stage absorption. Methane hydrogen dry gas is obtained at the top of the multi-stage absorption tower, and the liquid phase at the bottom of the reabsorption section is sent to the stabilization tower for (2) naphtha stabilization treatment of the whole plant.

2. The method for recovering light hydrocarbons by multi-stage absorption according to claim 1, wherein: The H2 / C1 coarse separation includes one of the following two methods: Method 1: Membrane separation: The sulfur-free rich gas is purified into hydrogen through a membrane separation unit to obtain purified hydrogen and rich gas after H2 / C1 coarse separation. The rich gas after H2 / C1 coarse separation is sent to a gas-liquid equilibrium; the pressure loss of the membrane separation tail gas is 0.2-0.5 MPag; Method 2: Pressure swing adsorption: The sulfur-free rich gas passes through the pressure swing adsorption unit to obtain hydrogen and rich gas after H2 / C1 coarse separation. The rich gas after H2 / C1 coarse separation is pressurized by the pressure swing adsorption tail gas compressor and sent to the gas-liquid balance; the rich gas after H2 / C1 coarse separation is pressurized to 2.5~4.5MPag by the pressure swing adsorption tail gas compressor.

3. The multi-stage absorption method for recovering light hydrocarbons according to claim 1, wherein: The operating temperature of the top of the stabilization tower is 40-60°C, and the operating pressure is 0.8-1.2 MPaG; The temperature of the reflux tank of the stabilization tower is 30-45°C; The operating temperature of the gas phase desulfurization tower is 40-45°C and the operating pressure is 2.5-4.5MPaG; The operating temperature of the crude hydrocarbon desulfurization tower is 35-45° C., and the operating pressure is 3.0-5.0 MPaG.

4. The multi-stage absorption method for recovering light hydrocarbons according to claim 1, wherein: The outlet pressure of the first raw gas compressor is 2.5-4.5 MPaG, the crude hydrocarbon containing sulfur and heavy components is sent to the middle part of the stabilization tower, and the rich gas containing sulfur and heavy components is sent to the upper part of the stabilization tower; The outlet pressure of the second raw gas compressor is 2.5-4.5 MPaG; Another part of the liquid phase at the bottom of the stabilization tower reflux tank is sent to the upper part of the stabilization tower.

5. The multi-stage absorption method for recovering light hydrocarbons according to claim 1, wherein: The temperature of the shallow cooler I is 15-20°C and the pressure is 2.0-4.0 MPag; The pressure of the multi-stage absorption tower is 2.0-4.0 MPag.

6. The method for recovering light hydrocarbons by multi-stage absorption according to claim 1, wherein: The top pressure of the demethanizer is 1.0-1.5 MPag; The top pressure of the deethanizer is 1.5-2.5 MPag; The top pressure of the depropanizer is 1.4-2.0 MPag.

7. The method for recovering light hydrocarbons by multi-stage absorption according to claim 1, wherein: The liquid phase at the bottom of the multi-stage absorption tower is mixed with the rich gas after H2 / C1 coarse separation to undergo (7) gas-liquid equilibrium treatment; The ratio of the total amount of absorbent in each section of the multi-stage absorption tower to the amount of gas phase entering the tower is controlled at 2 to 6.

8. A multi-stage absorption and recovery device for light hydrocarbons, characterized in that: The device comprises: a mixed naphtha feed pipeline, a hydrofining sulfur-rich gas feed pipeline, a stabilizing tower, a first raw gas compressor, a cooler I, a separator I, a second raw gas compressor, a cooler II, a separator II, a crude hydrocarbon pump II, a superheater, a gas phase desulfurization tower, a desulfurization and demercaptan unit, an H2 / C1 coarse separation unit, a shallow cooler I, a shallow cooler II, a separator IV, a multi-stage absorption tower, a demethanizer, a deethanizer and a depropanizer; the multi-stage absorption tower comprises, from bottom to top, a first absorption section, a second absorption section, a third absorption section, a fourth absorption section and a reabsorption section; Among them, the hydrofining sulfur-rich gas feed pipeline is connected to the first raw gas compressor, the cooler 1 and the separator 1 in sequence, and the separator 1 is provided with a separator 1 tank top discharge pipeline and a separator 1 tank bottom discharge pipeline; The mixed naphtha feed pipeline, the separator tank 1 top discharge pipeline and the separator tank 1 bottom discharge pipeline are connected to the stabilization tower, the stabilization tower is provided with a stabilization tower top discharge pipeline and a stabilization tower bottom discharge pipeline, the stabilization tower bottom discharge pipeline is divided into two branches, one of which is used as a mixed petroleum naphtha product discharge pipeline, and the other is connected to the reabsorption section of the multi-stage absorption tower. The upper part of the stabilization tower is also provided with a condenser and a stabilization tower reflux tank, the stabilization tower top discharge pipeline is connected to the condenser and the stabilization tower reflux tank in sequence, and the stabilization tower reflux tank is provided with a stabilization tower reflux tank top discharge pipeline and a stabilization tower reflux tank bottom discharge pipeline; The top discharge pipeline of the stabilization tower reflux tank is connected to the second raw gas compressor, cooler II and separator II in sequence, and the separator II is provided with a top discharge pipeline of the separator II tank and a bottom discharge pipeline of the separator II tank; The discharge pipeline from the top of the separator tank II is connected to the superheater and the gas phase desulfurization tower in sequence, and the gas phase desulfurization tower is provided with a gas phase desulfurization tower discharge pipeline; The discharging pipeline at the bottom of the stabilization tower reflux tank is connected to the stabilization tower reflux pump and is divided into two branches, one of which is connected to the desulfurization and sweetening tower. The discharging pipeline at the bottom of the separator tank II is connected to the crude hydrocarbon pump II and the desulfurization and sweetening tower in sequence. The desulfurization and sweetening tower is provided with a desulfurization and sweetening tower discharging pipeline. The gas phase desulfurization tower discharge pipeline is connected to the H2 / C1 coarse separation unit, and the H2 / C1 coarse separation unit is provided with a hydrogen discharge pipeline and a H2 / C1 coarse separation rich gas discharge pipeline, and the H2 / C1 coarse separation rich gas discharge pipeline is sequentially connected to the shallow cooler I and the separator tank IV, and the separator tank IV is provided with a separator tank IV tank top discharge pipeline and a separator tank IV tank bottom discharge pipeline; The bottom discharge pipeline of the liquid separator IV is connected to the demethanizer in sequence, and the demethanizer is provided with a demethanizer top discharge pipeline and a demethanizer bottom discharge pipeline, and the demethanizer top discharge pipeline is connected to the first raw gas compressor after merging with the hydrorefining sulfur-rich gas feed pipeline; the demethanizer bottom discharge pipeline is connected to the deethanizer, and the deethanizer is provided with a deethanizer top discharge pipeline and a deethanizer bottom discharge pipeline, and the deethanizer bottom discharge pipeline is divided into two branches, one of which is connected to the third absorption section of the multi-stage absorption tower, and the other is connected to the depropanizer; the depropanizer is provided with a depropanizer top discharge pipeline and a depropanizer bottom discharge pipeline, the depropanizer top discharge pipeline is connected to the second absorption section of the multi-stage absorption tower, and the depropanizer bottom discharge pipeline is divided into two branches, one of which is used as a mixed carbon four product discharge pipeline, and the other is connected to the fourth absorption section of the multi-stage absorption tower; The top discharge pipeline of the liquid separator IV is connected to the bottom of the first absorption section of the multi-stage absorption tower. The multi-stage absorption tower is provided with a top discharge pipeline of the multi-stage absorption tower, a bottom discharge pipeline of the reabsorption section of the multi-stage absorption tower and a bottom discharge pipeline of the multi-stage absorption tower. The bottom discharge pipeline of the reabsorption section of the multi-stage absorption tower merges with the mixed naphtha feed pipeline.

9. The multi-stage absorption and recovery device for light hydrocarbons according to claim 8, wherein: The H2 / C1 coarse separation unit includes the following two connection methods: Method 1: The gas phase desulfurization tower discharge pipeline is connected to the membrane separation unit, and the membrane separation unit is provided with a membrane separation unit hydrogen discharge pipeline and a membrane separation unit H2 / C1 coarse separation rich gas discharge pipeline, and the membrane separation unit H2 / C1 coarse separation rich gas discharge pipeline is connected to the shallow cooler I; Method 2: The gas phase desulfurization tower discharge pipeline is connected to the pressure swing adsorption unit, and the pressure swing adsorption unit is provided with a pressure swing adsorption unit hydrogen discharge pipeline and a pressure swing adsorption unit H2 / C1 coarse separation rich gas discharge pipeline. The pressure swing adsorption unit H2 / C1 coarse separation rich gas discharge pipeline is connected to the pressure swing adsorption tail gas compressor and the shallow cooler I in sequence.

10. The multi-stage absorption and recovery device for light hydrocarbons according to claim 8, wherein: The discharge line from the top of the liquid separator tank 1 is connected to the upper part of the stabilization tower, and the discharge line from the bottom of the liquid separator tank 1 is connected to the middle part of the stabilization tower; The other discharge pipeline from the bottom of the stabilization tower reflux tank is connected to the upper part of the stabilization tower; The bottom discharge pipeline of the multi-stage absorption tower merges with the discharge pipeline of the gas phase desulfurization tower.

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