Saturated light hydrocarbon comprehensive recovery device capable of flexibly adjusting recovery components

Abstract

The invention belongs to the field of oil refining and chemical engineering, and relates to a comprehensive saturated light hydrocarbon recovery method and device capable of flexibly adjusting recovery components. The method has the following advantages: the naphtha-containing liquid phase after the atmospheric and vacuum distillation unit, each hydrofining unit and the sulfur-containing gas phase are pressurized and cooled is concentrated and stabilized, the content of heavy components in the sulfur-containing rich gas is reduced, and the foaming risk of the gas phase desulfurization tower is reduced; the tail gas of the whole plant is uniformly brought into a recovery range, so that the recovery range is enlarged, and the loss of C2 and above components is reduced; 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 secondary separation problem of key components is reduced; crude hydrocarbon after desulfurization and mercaptan removal and crude hydrocarbon condensed by a cooler at an outlet of a third raw material gas compressor are sent to the middle section of the 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; according to the needs of a refinery plant, whether C2 components need to be recycled or not can be flexibly adjusted, and adaptability is high.

Description

Technical Field

[0001] The present invention belongs to the field of oil refining and chemical industry, and specifically relates to a comprehensive recovery method and device for saturated light hydrocarbons with flexible adjustment of recovery components. More specifically, it relates to a device and method for recovering saturated light hydrocarbons in the entire refinery by-products of saturated light hydrocarbons with flexible adjustment of recovery components from atmospheric and vacuum treatment, hydrocracking, hydrofining, aromatics reforming and other devices in the refinery. Background Art

[0002] Saturated light hydrocarbons in refineries primarily come from atmospheric and vacuum unit overhead gas and mixed naphtha, overhead rich gas and crude hydrocarbons from the hydrogen sulfide stripping towers of various hydrocracking units, fuel gas from various hydrotreating units, disproportionated isomerization tail gas and pre-hydrogenated fuel gas from aromatics reforming units, hydroprocessing low-fraction PSA tail gas, reforming PSA tail gas, and hydrocracking membrane separation tail gas. Light hydrocarbon recovery from these streams primarily involves atmospheric and vacuum unit light hydrocarbon recovery and various hydrocracking absorption and stabilization systems to recover liquefied gas components such as C3 and C4. C2 is used in dry gas as fuel. With the development of integrated refining and chemical integration, further recovery of C2 from dry gas to provide lightweight ethylene feed for ethylene plants has attracted significant attention. Chemical refineries with ethylene plants typically install new C2 recovery units to further recover C2 from dry gas. This ethane-rich gas is then fed to the ethylene unit cracking furnaces as cracking feed, reducing external ethylene feed purchases and further improving the refinery's economic efficiency.

[0003] The conventional process setup involves 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, which results in 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. 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] At the same time, taking into account the problem of asynchronous inspection and maintenance of the refining unit and the ethylene unit, when the refining unit and the ethylene unit are running at the same time, the saturated light hydrocarbon comprehensive recovery unit with flexible adjustment of recovery components is mainly used to produce ethylene materials and recover C2 and above components. When the ethylene unit is shut down for inspection and maintenance, the unit should mainly produce liquefied gas products, and C2 and below components are sent to fuel gas, and C2 components are no longer recovered. The saturated light hydrocarbon comprehensive recovery technology with flexible adjustment of recovery components is required to handle these two working conditions.

[0005] 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, while adapting to the flexibility of selectively considering whether to recover the carbon two component according to the needs of the ethylene unit. Summary of the Invention

[0006] The present invention aims to provide a comprehensive saturated light hydrocarbon recovery device and method that allows for flexible adjustment of recovery components throughout the plant, with a rational component separation sequence, reduced energy consumption, and optimized equipment quantity. This method can achieve comprehensive recovery of saturated light hydrocarbons in atmospheric and vacuum units, hydrocracking units, hydrogen refining units, and aromatics reforming units, optimizing absorption tower operating conditions and reducing energy consumption. Furthermore, a method for recovering liquefied gas components can be provided based on the need to recover C2 components.

[0007] To achieve the above-mentioned object, the first aspect of the present invention provides a comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components, including: a method for recovering C2 and above components and a method for recovering liquefied gas components;

[0008] When recovering C2 and above components, the system for recovering liquefied gas components is closed, the control valve of the LPG reboiler in the middle of the demethanizer is closed, and the control valves of the reboiler in the middle of the demethanizer and the reboiler at the bottom of the demethanizer are opened, including 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 top gas phase of the stabilization tower is obtained at the top of the tower. After condensation in the condenser, it is sent to the stabilization tower reflux tank to obtain the top rich gas of the stabilization tower reflux tank and the bottom liquid phase 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 is superheated in the superheater and then 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 rich gas from the gas phase desulfurization tower;

[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 divided 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. After removing hydrogen sulfide and mercaptan, crude hydrocarbon is obtained from the desulfurization and demercaptan tower.

[0014] (6) Gas phase pressurization III: The PSA tail gas is pressurized by the third raw gas compressor, cooled by cooler III, and separated by separator III to obtain a gas phase at the top of separator III and a liquid phase at the bottom of separator III;

[0015] (7) Gas-liquid balance: The rich gas from the gas phase desulfurization tower, the gas phase at the top of the separator III tank, and the tail gas separated by the hydrocracking membrane are mixed to obtain sulfur-free rich gas. The sulfur-free rich gas is cooled by the shallow cooler I and then enters the separator IV for separation to obtain the gas phase at the top of the separator IV tank and the liquid phase at the bottom of the separator IV tank;

[0016] (8) C1 / C2 separation: The gas phase at the top of the separator IV enters the absorption tower for C1 / C2 separation, wherein the liquid phase at the bottom of the separator III is extracted by the crude hydrocarbon pump III and mixed with the crude hydrocarbon of the desulfurization and demercaptan unit to obtain sulfur-free crude hydrocarbon, which is then cooled by the shallow cooler II and sent to the middle section of the absorption tower as the absorbent in the middle of the absorption tower. At least one of a mixture of C4, normal C4, isomeric C4 and liquefied gas is used as the absorbent at the top of the absorption tower to obtain the gas phase at the top of the absorption tower and the liquid phase at the bottom of the absorption tower. The liquid phase at the bottom of the absorption tower is returned to be mixed with the sulfur-free rich gas for gas-liquid equilibrium;

[0017] (9) C3 / C4 separation: The liquid phase at the bottom of separator IV is further separated by a demethanizer and a depropanizer to obtain an ethane-rich gas product and a mixed C4 product;

[0018] (10) Reabsorption: The gas phase at the top of the absorption tower is sent to the reabsorption tower to recover C3 and above components, and another part of the stabilized naphtha is used as the reabsorbent. The gas phase at the top of the reabsorption tower is produced as dry gas, and the liquid phase at the bottom of the reabsorption tower is returned to the stabilization tower;

[0019] When only the liquefied gas component is recovered, the liquefied gas component recovery system is opened, the control valves of the intermediate reboiler and the bottom reboiler of the demethanizer are closed, and the control valve of the LPG reboiler in the intermediate of the demethanizer is opened, including the following steps:

[0020] (11) By adjusting the system for recovering liquefied gas components, closing the membrane separation tail gas control valve and the PSA tail gas control valve, stopping the operation of the third raw gas compressor, opening the cross-line control valve, closing the absorption tower inlet control valve, and using the naphtha component steam at the bottom of the depropanizer as the heat source for the LPG reboiler in the middle of the demethanizer; the liquid phase at the bottom of the separator IV tank enters the demethanizer and the depropanizer for further separation to obtain a liquefied gas product (S-11LPG) and a naphtha component (S-10LPG);

[0021] (12) Reabsorption: The gas phase at the top of separator IV is sent to the reabsorption tower to recover C3 and components above C3. The gas phase at the top of the reabsorption tower is extracted as dry gas, and the liquid phase at the bottom of the reabsorption tower is returned to the stabilization tower.

[0022] In the present invention, the mixed naphtha comes from various hydrogen refining devices, atmospheric and vacuum devices, and the gas and liquid phases of various hydrogen-refined sulfur-containing fuel gases after passing through the first raw gas compressor and cooling and liquid separation, thereby reducing the carbon five and above components in the sulfur-containing fuel gas and reducing the risk of foaming in the gas phase desulfurization tower.

[0023] According to the present invention, gas phase desulfurization adopts medium and high pressure desulfurization to reduce the amount of lean amine liquid and the diameter of the desulfurization tower, and a sulfur-rich gas superheater is set in front of the gas phase desulfurization tower.

[0024] According to the present invention, the crude hydrocarbons in the reflux tank of the stabilization tower are pressurized by a reflux pump, and are sent to the desulfurization and demercaptan after the degree of supercooling is increased. After the gas phase in the reflux tank of the stabilization tower is pressurized by the second raw gas compressor, cooled by the cooler, and separated by the liquid separator, a part of the C3 / C4 components in the gas phase will be condensed into the liquid phase, thereby reducing the content of the heavy components in the gas phase and reducing the risk of foaming in the gas phase desulfurization tower. The liquid phase is pressurized by a pump, and is sent to the desulfurization and demercaptan after the degree of supercooling is increased.

[0025] According to the present invention, the top of the absorption tower uses poor C4 as the absorbent, and the middle of the tower uses raw crude hydrocarbon as the absorbent, which jointly absorb C2 and above components in the raw gas to achieve C1 / C2 separation.

[0026] According to the present invention, the intermediate reboiler and the bottom reboiler of the demethanizer use the depleted carbon four at the bottom of the depropanizer as the heat source, do not need to consume steam, and no cooling reflux is set at the top of the tower, and directly return to the inlet of the third raw gas compressor.

[0027] According to the present invention, the bottom of the depropanizer is poor in carbon four, part of which is sent to the top of the absorption tower as a circulating absorbent after passing through the intermediate reboiler of the demethanizer and the bottom reboiler, and part of it is sent out of the device. The top of the tower is a mixture of carbon two, carbon three and carbon four components, and carbon three and carbon four are no longer strictly separated. The top gas is sent to the ethylene unit for cracking.

[0028] According to the present invention, the dry gas from the top of the absorption tower is sent to the reabsorption tower, and the stabilized naphtha at the bottom of the stabilization tower is used as the reabsorbent to recover the entrained C4 absorbent and reduce the absorbent loss. The mixed naphtha at the bottom of the tower is then returned to the stabilization tower.

[0029] According to the present invention, when it is not necessary to recover the carbon two component, the liquefied gas component recovery system is used to close the PSA tail gas pipeline and the membrane separation pipeline control valve, stop the operation of the third raw gas compressor, open the valve from the gas-liquid balance separator IV to the bottom of the reabsorption tower, close the valve from the gas-liquid balance separator IV to the bottom of the absorption tower, close the bottom pipeline of the depropanizer to the intermediate reboiler of the demethanizer and the valve of the bottom reboiler, open the valve from the intermediate LPG reboiler of the demethanizer to the depropanizer, and open the steam valve of the intermediate LPG reboiler pipe side of the intermediate LPG reboiler.

[0030] According to the present invention, preferably, when only the liquefied gas component is recovered, the following steps are also included: opening the control valve from the demethanizer to the second raw gas compressor, closing the circulating light hydrocarbon control valve, the light hydrocarbon control valve at the bottom of the absorption tower, and the control valve from the absorption tower to the reabsorption tower.

[0031] 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.

[0032] According to the present invention, preferably, the operating temperature of the stabilization tower reflux tank is 30-45°C.

[0033] 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.

[0034] According to the present invention, preferably, the operating temperature of the desulfurization and demercaptan tower is 35-45° C., and the operating pressure is 3.0-5.0 MPaG.

[0035] 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.

[0036] 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 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.

[0037] According to the present invention, preferably, the outlet pressure of the second raw gas compressor is 2.5-4.5 MPaG.

[0038] 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.

[0039] According to the present invention, preferably, another portion of the stabilized naphtha is used as a reabsorbent (S-13).

[0040] 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.

[0041] According to the present invention, preferably, the pressure of the absorption tower is 2.0-4.0 MPag.

[0042] According to the present invention, preferably, the liquid phase at the bottom of the liquid tank IV enters the demethanizer, the gas phase obtained at the top of the demethanizer is returned and mixed with the PSA tail gas, and the gas phase is pressurized III, and the liquid phase at the bottom of the demethanizer is sent to the depropanizer, and an ethane-rich gas product is obtained at the top of the tower, and a mixed C4 product is obtained at the bottom of the tower.

[0043] According to the present invention, preferably, part of the mixed C4 product is used as the C4-depleted absorbent circulated at the top of the absorption tower.

[0044] According to the present invention, preferably, the top pressure of the demethanizer is 1.0-1.5 MPag.

[0045] According to the present invention, preferably, the top pressure of the depropanizer is 1.4-2.0 MPag.

[0046] A second aspect of the present invention provides a comprehensive recovery device for saturated light hydrocarbons with flexible adjustment of recovery components, the device comprising: a mixed naphtha feed line, a hydrorefining sulfur-rich gas feed line, a PSA tail gas feed line, a hydrocracking membrane separation tail gas feed line, 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 sweetening unit, a third raw gas compressor, a cooler III, a liquid separator III, a crude hydrocarbon pump III, a shallow cooler I, a shallow cooler II, a liquid separator IV, an absorption tower, a demethanizer, a depropanizer, a reabsorption tower, and a liquefied gas recovery system;

[0047] 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;

[0048] 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, the upper part of the stabilization tower is also provided with a condenser, a stabilization tower reflux tank and a stabilization tower reflux pump, the stabilization tower top discharge pipeline is sequentially connected to the condenser and the stabilization tower reflux tank, 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;

[0049] 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;

[0050] 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;

[0051] 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.

[0052] The PSA tail gas feed pipeline is connected to the third raw gas compressor, cooler III and separator III in sequence, and the separator III is provided with a separator III tank top discharge pipeline and a separator III tank bottom discharge pipeline; the PSA tail gas feed pipeline is provided with a PSA tail gas control valve;

[0053] The top discharge pipeline of the liquid separator III, the hydrocracking membrane separation tail gas feed pipeline and the gas phase desulfurization tower discharge pipeline are merged into a sulfur-free rich gas pipeline, which is then sequentially connected to the shallow cooler I and the liquid separator IV. The liquid separator IV is provided with a top discharge pipeline of the liquid separator IV and a bottom discharge pipeline of the liquid separator IV; the hydrocracking membrane separation tail gas feed pipeline is provided with a membrane separation tail gas control valve;

[0054] The discharge pipeline from the top of the separator IV tank is divided into two branches, one of which is connected to the absorption tower and is provided with an absorption tower air intake control valve, and the other is connected to the reabsorption tower and is provided with a cross-line control valve;

[0055] The bottom discharge pipeline of the separator III is connected to the crude hydrocarbon pump III, and then merges with the discharge pipeline of the desulfurization and demercaptan tower, and then sequentially connected to the shallow cooler II and the middle part of the absorption tower. The absorption tower is provided with an absorption tower top discharge pipeline and an absorption tower bottom discharge pipeline, and the absorption tower bottom discharge pipeline merges with the sulfur-free rich gas pipeline;

[0056] The bottom discharge pipeline of the separator IV is connected to the demethanizer and the depropanizer. The demethanizer is provided with a demethanizer intermediate reboiler, a demethanizer intermediate LPG reboiler, a demethanizer bottom reboiler and a demethanizer top discharge pipeline. The demethanizer top discharge pipeline is divided into two branches, one of which merges with the PSA tail gas feed pipeline; the demethanizer intermediate reboiler, the intermediate LPG reboiler and the demethanizer bottom reboiler are all provided with control valves;

[0057] The top discharge pipeline of the absorption tower is connected to the reabsorption tower, and the reabsorption tower is provided with a top discharge pipeline of the reabsorption tower and a bottom discharge pipeline of the reabsorption tower, and the bottom discharge pipeline of the reabsorption tower is connected to the middle of the stabilization tower;

[0058] The cross-line control valve, membrane separation tail gas control valve, PSA tail gas control valve, and absorption tower air inlet control valve are connected to the liquefied gas recovery system.

[0059] According to the present invention, preferably, the discharge line from the top of the liquid separator tank I is connected to the upper part of the stabilization tower, and the discharge line from the bottom of the liquid separator tank I is connected to the middle part of the stabilization tower; another discharge line from the bottom of the stabilization tower is connected to the reabsorption tower; and another discharge line from the bottom of the reflux tank of the stabilization tower is connected to the upper part of the stabilization tower.

[0060] According to the present invention, preferably, the bottom discharge pipeline of the absorption tower is provided with a light hydrocarbon control valve at the bottom of the absorption tower; another demethanizer top discharge pipeline merges with the top discharge pipeline of the stabilization tower reflux tank, and the pipeline is provided with a demethanizer to second raw gas compressor control valve; the depropanizer is provided with a depropanizer top discharge pipeline and a depropanizer bottom discharge pipeline, the depropanizer bottom discharge pipeline is divided into two branches, one of which is connected to the upper part of the absorption tower, and a circulating light hydrocarbon control valve is provided on the pipeline; the absorption tower top discharge pipeline is provided with an absorption tower to reabsorption tower control valve.

[0061] According to the present invention, preferably, the circulating light hydrocarbon control valve, the light hydrocarbon control valve at the bottom of the absorption tower, the control valve from the absorption tower to the reabsorption tower, and the control valve from the demethanizer to the second raw gas compressor are connected to the liquefied gas recovery system.

[0062] Compared with the prior art, the present invention has the following advantages:

[0063] (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.

[0064] (2) In the present invention, each hydrotreated sulfur-containing fuel gas, hydrotreated low-fraction gas PSA tail gas, reformed hydrogen PSA tail gas, disproportionated and post-hydrogenated fuel gas, and hydrocracking membrane separation tail gas are uniformly included in the recovery range for centralized recovery, thereby increasing the recovery range and reducing the loss of carbon dioxide and above components.

[0065] (3) 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.

[0066] (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 middle section of the absorption tower, and the C3 to C5 components contained in the raw materials themselves are used as absorbents, thereby reducing the amount of circulating C4 and helping to reduce energy consumption.

[0067] (5) The present invention can flexibly adjust whether to recover the carbon two component according to the needs of the refinery, and has strong adaptability.

[0068] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] 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.

[0070] Figure 1 The process flow chart of the comprehensive recovery of saturated light hydrocarbons with flexible adjustment of recovery components in the present invention is shown.

[0071] Description of reference numerals:

[0072] 1. Stabilization tower; 2. Stabilization tower reflux tank; 3. Stabilization tower reflux pump; 4. Second raw gas compressor; 5. Cooler II; 6. Separator II; 7. Crude hydrocarbon pump II; 8. Superheater; 9. Gas phase desulfurization tower; 10. First raw gas compressor; 11. Cooler I; 12. Separator I; 13. Third raw gas compressor; 14. Cooler III; 15. Separator III; 16. Crude hydrocarbon pump III; 17. Shallow cooler I; 18. Shallow cooler II; 19. Desulfurization and sweetening unit; 23. Separator IV; 24. Absorption tower; 25. Demethanizer; 26. Depropanizer; 27. Reabsorption tower;

[0073] 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-5, PSA tail gas; S-6, sulfur-free rich gas; S-7, sulfur-free crude hydrocarbons; S-9, circulating C4-poor absorbent; S-10, mixed C4 product; S-11, ethane-rich gas product; S-12, dry gas; S-13, reabsorbent; S-14, mixed naphtha product; S-15, hydrocracking membrane separation tail gas; S-10, LPG, naphtha component; S-11, LPG, liquefied gas product;

[0074] V1: cross-line control valve; V2: membrane separation tail gas control valve; V3: PSA tail gas control valve; V4: circulating light hydrocarbon control valve; V5: light hydrocarbon control valve at the bottom of the absorption tower; V6: control valve from the absorption tower to the reabsorption tower; V7: absorption tower air inlet control valve; V8: demethanizer to the second raw gas compressor control valve. DETAILED DESCRIPTION

[0075] 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.

[0076] Example 1

[0077] A comprehensive saturated light hydrocarbon recovery device with flexible adjustment of recovery components comprises: a mixed naphtha feed pipeline, a hydrorefining sulfur-rich gas feed pipeline, a PSA tail gas feed pipeline, a hydrocracking membrane separation tail 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 sweetening unit 19, a third raw gas compressor 13, a cooler III 14, a separator III 15, a crude hydrocarbon pump III 16, a shallow cooler I17, a shallow cooler II 18, a separator IV 23, an absorption tower 24, a demethanizer 25, a depropanizer 26, a reabsorption tower 27, and a liquefied gas recovery system;

[0078] Among them, the hydrofining sulfur-rich gas feed pipeline is connected to the first raw gas compressor 10, the cooler I11 and the separator I12 in sequence, and the separator I12 is provided with a separator I tank top discharge pipeline and a separator I tank bottom discharge pipeline;

[0079] 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 1, the stabilization tower 1 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 tower 27. The upper part of the stabilization tower is also provided with a condenser, a stabilization tower reflux tank 2 and a stabilization tower reflux pump 3. The stabilization tower top discharge pipeline is sequentially connected to the condenser and the stabilization tower reflux tank 2. The stabilization tower reflux tank 2 is provided with a stabilization tower reflux tank top discharge pipeline and a stabilization tower reflux tank bottom discharge pipeline;

[0080] 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 6 is provided with a top discharge pipeline of the separator II tank and a bottom discharge pipeline of the separator II tank;

[0081] The discharge pipeline from the top of the separator tank II is connected to the superheater 8 and the gas phase desulfurization tower 9 in sequence, and the gas phase desulfurization tower 9 is provided with a gas phase desulfurization tower discharge pipeline;

[0082] After the stabilization tower reflux tank bottom discharge pipeline is connected to the stabilization tower reflux pump 3, it is divided into two branches, one of which is connected to the desulfurization and sweetening tower 19, and the other stabilization tower reflux tank bottom discharge pipeline is connected to the upper part of the stabilization tower, and the separator tank II tank bottom discharge pipeline is sequentially connected to the crude hydrocarbon pump II 7 and the desulfurization and sweetening tower 19, and the desulfurization and sweetening tower 19 is provided with a desulfurization and sweetening tower discharge pipeline;

[0083] The PSA tail gas feed pipeline is connected to the third raw gas compressor 13, the cooler III 14 and the separator III 15 in sequence. The separator III 15 is provided with a separator III tank top discharge pipeline and a separator III tank bottom discharge pipeline; the PSA tail gas feed pipeline is provided with a PSA tail gas control valve V3;

[0084] The top discharge pipeline of the separator III, the hydrocracking membrane separation tail gas feed pipeline and the gas phase desulfurization tower discharge pipeline are merged into a sulfur-free rich gas pipeline, which is then connected in sequence to the shallow cooler I17 and the separator IV 23. The separator IV 23 is provided with a top discharge pipeline of the separator IV and a bottom discharge pipeline of the separator IV; the hydrocracking membrane separation tail gas feed pipeline is provided with a membrane separation tail gas control valve V2;

[0085] The discharge pipeline from the top of the separator IV is divided into two branches, one of which is connected to the absorption tower 24 and is provided with an absorption tower air inlet control valve V7, and the other is connected to the reabsorption tower 27 and is provided with a cross-line control valve V1;

[0086] The bottom discharge line of the separator III is connected to the crude hydrocarbon pump III 16, and then merges with the discharge line of the desulfurization and demercaptan tower, and then sequentially connected to the shallow cooler II 18 and the middle part of the absorption tower. The absorption tower 24 is provided with an absorption tower top discharge line and an absorption tower bottom discharge line, and the absorption tower bottom discharge line merges with the sulfur-free rich gas pipeline;

[0087] The bottom discharge pipeline of the separator IV is connected to the demethanizer 25 and the depropanizer 26. The demethanizer 25 is provided with a demethanizer intermediate reboiler, a demethanizer intermediate LPG reboiler, a demethanizer bottom reboiler and a demethanizer top discharge pipeline. The demethanizer top discharge pipeline is divided into two branches, one of which merges with the PSA tail gas feed pipeline; the demethanizer intermediate reboiler, the intermediate LPG reboiler and the demethanizer bottom reboiler are connected to the depropanizer 26. The reboilers are all equipped with control valves; another demethanizer top discharge pipeline merges with the stabilization tower reflux tank top discharge pipeline, and a demethanizer to second raw gas compressor control valve V8 is provided on the pipeline; the depropanizer 26 is provided with a depropanizer top discharge pipeline and a depropanizer bottom discharge pipeline, and the depropanizer bottom discharge pipeline is divided into two branches, one of which is connected to the upper part of the absorption tower, and a circulating light hydrocarbon control valve V4 is provided on the pipeline;

[0088] The top discharge pipeline of the absorption tower is connected to the reabsorption tower 27, and the reabsorption tower 27 is provided with a top discharge pipeline of the reabsorption tower and a bottom discharge pipeline of the reabsorption tower. The bottom discharge pipeline of the reabsorption tower is connected to the middle part of the stabilization tower; the bottom discharge pipeline of the absorption tower is provided with a light hydrocarbon control valve V5 at the bottom of the absorption tower, and the top discharge pipeline of the absorption tower is provided with a control valve V6 from the absorption tower to the reabsorption tower;

[0089] The cross-line control valve V1, membrane separation tail gas control valve V2, PSA tail gas control valve V3, the circulating light hydrocarbon control valve V4, the light hydrocarbon control valve V5 at the bottom of the absorption tower, the control valve V6 from the absorption tower to the reabsorption tower, the air inlet control valve V7 of the absorption tower, and the control valve V8 from the demethanizer to the second raw gas compressor are connected to the liquefied gas recovery system.

[0090] A comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components, which only recovers C2 and above components, shuts down the system for recovering liquefied gas components, closes the control valve of the LPG reboiler in the middle of the demethanizer, and opens the control valves of the middle reboiler and the bottom reboiler in the demethanizer, comprising the following steps:

[0091] (1) Gas phase pressurization I: The hydrorefined sulfur-rich gas S-4 is compressed and pressurized by the first raw gas compressor 10, cooled by the cooler I11, and separated by the liquid separator I12. The sulfur-rich and heavy component rich gas S-2 is obtained at the top of the tank, and the sulfur-rich and heavy component crude hydrocarbons S-3 is obtained at the bottom of the tank; the outlet pressure of the first raw gas compressor is 3.0 MPag, the sulfur-rich and heavy component crude hydrocarbons are sent to the middle part of the stabilization tower, and the sulfur-rich and heavy component rich gas is sent to the upper part of the stabilization tower.

[0092] (2) Naphtha stabilization in the whole plant: mixed naphtha S-1, sulfur-containing and heavy component rich gas S-2 and sulfur-containing and heavy component crude hydrocarbon S-3 are sent to stabilization tower 1 for stabilization treatment, and stabilized naphtha is obtained at the bottom of the tower and divided into two parts, one part of which is used as mixed naphtha product S-14 and the other part is used as reabsorbent S-13. The top gas phase of the stabilization tower is obtained at the top of the tower, which is condensed in a condenser and sent to the stabilization tower reflux tank to obtain the top rich gas of the stabilization tower reflux tank and the bottom liquid phase of the stabilization tower reflux tank; 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 operating temperature of the stabilization tower reflux tank is 30-45°C.

[0093] (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 4 for compression and pressure boosting, cooled in cooler II 5, and separated in separator II 6 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 second raw gas compressor is 3.0 MPag.

[0094] (4) Rich gas desulfurization: The rich gas at the top of the separator II is superheated in the superheater 8 and then sent to the gas phase desulfurization tower 9, where it is in reverse contact with the lean amine liquid to remove hydrogen sulfide and obtain the rich gas of the gas phase desulfurization tower; the superheater outlet temperature is 43°C, and the overheating is 3°C.

[0095] (5) Crude hydrocarbon desulfurization: The liquid phase at the bottom of the stabilization tower reflux tank is pressurized by the stabilization tower reflux pump 3 and then divided into two parts. One part enters the desulfurization and demercaptan tower 19, and the other part is sent to the upper part of the stabilization tower. The liquid phase at the bottom of the separator tank II is pumped out by the crude hydrocarbon pump II 7 and sent to the desulfurization and demercaptan tower 19. After removing hydrogen sulfide and mercaptan, crude hydrocarbon in the desulfurization and demercaptan tower is obtained.

[0096] (6) Gas Phase Pressure Boosting III: The PSA tail gas S-5 is pressurized by the third raw gas compressor 13, cooled by the cooler III 14, and separated by the separator III 15 to obtain a gas phase at the top of the separator III and a liquid phase at the bottom of the separator III.

[0097] (7) Gas-liquid balance: The rich gas from the gas phase desulfurization tower, the gas phase at the top of the separator III, and the tail gas S-15 separated by the hydrocracking membrane are mixed to obtain sulfur-free rich gas S-6. The sulfur-free rich gas S-6 is cooled by the shallow cooler I17 and then enters the separator IV 23 for separation to obtain the gas phase at the top of the separator IV and the liquid phase at the bottom of the separator IV; the temperature of the shallow cooler I is 15-20°C, and the pressure is 2.0-4.0 MPag.

[0098] (8) C1 / C2 separation: The gas phase at the top of the separator IV enters the absorption tower 24 for C1 / C2 separation. The liquid phase at the bottom of the separator III is extracted by the crude hydrocarbon pump III 16 and mixed with the crude hydrocarbon of the desulfurization and demercaptanization unit to obtain sulfur-free crude hydrocarbon S-7. After cooling in the shallow cooler II 18, it is sent to the middle section of the absorption tower as the absorbent in the middle of the absorption tower. At least one of mixed C4, normal C4, isomeric C4 and liquefied gas is used as the absorbent at the top of the absorption tower to obtain the gas phase at the top of the absorption tower and the liquid phase at the bottom of the absorption tower. The liquid phase at the bottom of the absorption tower is returned and mixed with the sulfur-free rich gas S-6 to perform gas-liquid equilibrium. The pressure of the absorption tower is 2.0 to 4.0 MPag.

[0099] (9) C3 / C4 separation: The liquid phase at the bottom of separator IV is further separated by a demethanizer 25 and a depropanizer 26 to obtain an ethane-rich gas product S-11 and a mixed C4 product S-10; the top pressure of the demethanizer is 1.0-1.5 MPag, and the top pressure of the depropanizer is 1.4-2.0 MPag.

[0100] (10) Reabsorption: The gas phase at the top of the absorption tower is sent to the reabsorption tower 27 to recover C3 and components above C3, and another part of the stabilized naphtha is used as the reabsorbent. The gas phase at the top of the reabsorption tower is produced as dry gas S-12, and the liquid phase at the bottom of the reabsorption tower is returned to the stabilization tower 1.

[0101] The composition and properties of the products of dry gas, ethane-rich gas and mixed C4 separated from light hydrocarbons by the above method are shown in Tables 1 to 3.

[0102] Table 1 Dry gas properties

[0103] Temperature, °C 40 Pressure, MPag 3.0 composition v％ <![CDATA[H2]]> 39.2279 CO 0.0188 <![CDATA[N2]]> 1.4736 <![CDATA[CH4]]> 58.7293 <![CDATA[C2H6]]> 0.0392 <![CDATA[NC4H 10 ]]> 0.0107 <![CDATA[C5+]]> 0.5005

[0104] Table 2 Properties of ethane-rich gas

[0105]

[0106]

[0107] Table 3 Properties of mixed C4

[0108] Temperature, °C 40 Pressure, MPag 1.0 composition wt% <![CDATA[C3H8]]> 0.6677 <![CDATA[IC4H 10 ]]> 32.7307 <![CDATA[NC4H 10 ]]> 53.7325 <![CDATA[IC4H8]]> 0.0010 <![CDATA[TC4H8]]> 0.1478 <![CDATA[H2O]]> 1.9117 MDEA 0.0051 <![CDATA[C5+]]> 10.8034

[0109] Example 2

[0110] The present embodiment is the same as Example 1, but differs from Example 1 in that, when only the liquefied gas component is recovered, the liquefied gas component recovery system is opened, the control valves of the intermediate reboiler and the bottom reboiler of the demethanizer are closed, and the control valve of the LPG reboiler in the intermediate of the demethanizer is opened, comprising the following steps:

[0111] (11) By adjusting the system for recovering liquefied gas components, closing the membrane separation tail gas control valve V2 and the PSA tail gas control valve V3, stopping the operation of the third raw gas compressor 13, opening the cross-line control valve V1, closing the absorption tower air inlet control valve V7, and using the naphtha component steam at the bottom of the depropanizer as the heat source for the LPG reboiler in the middle of the demethanizer; the liquid phase at the bottom of the separator IV enters the demethanizer 25 and the depropanizer 26 for further separation to obtain the liquefied gas product S-11LPG and the naphtha component S-10LPG;

[0112] (12) Reabsorption: The gas phase at the top of separator IV is sent to reabsorption tower 27 to recover C3 and above components. The gas phase at the top of the reabsorption tower is produced as dry gas S-12, and the liquid phase at the bottom of the reabsorption tower is returned to stabilization tower 1. The properties of the liquefied gas are shown in Table 4.

[0113] Table 4 Properties of Liquefied Gas

[0114] temperature ℃ 40 pressure MPag 1.9 Mole fraction mol% <![CDATA[C2H6]]> 1.9999％ <![CDATA[C3H6]]> 0.0032％ <![CDATA[C3H8]]> 31.6632％ <![CDATA[IC4H 10 ]]> 31.2579％ <![CDATA[NC4H 10 ]]> 33.1922％ <![CDATA[IC4H8]]> 0.0011％ <![CDATA[H2S]]> 0.0002％ C5+ 1.4284％ <![CDATA[H2O]]> 0.4538％

[0115] 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 comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components, characterized in that: include: Methods for recovering carbon dioxide and above components and recovering liquefied gas components; When recovering C2 and above components, the system for recovering liquefied gas components is closed, the control valve of the LPG reboiler in the middle of the demethanizer is closed, and the control valves of the reboiler in the middle of the demethanizer and the reboiler at the bottom of the demethanizer are opened, including the following steps: (1) Gas phase pressure increase I: The hydrotreated sulfur-rich gas (S-4) is compressed and pressurized by the first raw gas compressor (10), cooled by the cooler I (11), and separated by the liquid separator I (12), and the sulfur-rich and heavy component rich gas (S-2) is obtained at the top of the tank, and the sulfur-rich and heavy component crude hydrocarbons (S-3) are obtained at the bottom of the tank; (2) Naphtha stabilization in the whole plant: mixed naphtha (S-1), sulfur-containing and heavy component rich gas (S-2) and sulfur-containing and heavy component crude hydrocarbon (S-3) are sent to the stabilization tower (1) for stabilization treatment. Stabilized naphtha is obtained at the bottom of the tower and divided into two parts, one of which is used as the mixed naphtha product (S-14). The top of the tower is the stabilization tower top gas phase, which is condensed in the condenser and sent to the stabilization tower reflux tank to obtain the stabilization tower reflux tank top rich gas and the stabilization tower reflux tank bottom liquid phase; (3) Gas phase pressure boosting II: The rich gas at the top of the stabilizing tower reflux tank is sent to the second raw gas compressor (4) for compression and pressure boosting, cooled by cooler II (5), and separated by liquid separator II (6), thereby obtaining the rich gas at the top of the liquid separator II and the liquid phase at the bottom of the liquid separator II; (4) Rich gas desulfurization: The rich gas at the top of the separator II is superheated by the superheater (8) and then sent to the gas phase desulfurization tower (9), where it is in reverse contact with the lean amine liquid to remove hydrogen sulfide and obtain gas phase desulfurization tower 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 (3) and then divided into two parts, one of which enters the desulfurization and demercaptan tower (19). The liquid phase at the bottom of the separator II tank is pumped out by the crude hydrocarbon pump II (7) and sent to the desulfurization and demercaptan tower (19). After hydrogen sulfide and mercaptan are removed, crude hydrocarbon in the desulfurization and demercaptan tower is obtained. (6) Gas phase pressurization III: The PSA tail gas (S-5) is pressurized by the third raw gas compressor (13), cooled by the cooler III (14), and separated by the separator III (15) to obtain a gas phase at the top of the separator III and a liquid phase at the bottom of the separator III; (7) Gas-liquid balance: The rich gas from the gas phase desulfurization tower, the gas phase at the top of the separator III tank and the tail gas separated by the hydrocracking membrane (S-15) are mixed to obtain sulfur-free rich gas (S-6). The sulfur-free rich gas (S-6) is cooled by the shallow cooler I (17) and then enters the separator IV (23) for separation to obtain the gas phase at the top of the separator IV tank and the liquid phase at the bottom of the separator IV tank; (8) C1 / C2 separation: The gas phase at the top of the separator IV enters the absorption tower (24) for C1 / C2 separation, wherein the liquid phase at the bottom of the separator III is extracted by the crude hydrocarbon pump III (16) and mixed with the crude hydrocarbon of the desulfurization and demercaptan unit to obtain sulfur-free crude hydrocarbon (S-7), which is then cooled by the shallow cooler II (18) and sent to the middle section of the absorption tower as the absorbent in the middle of the absorption tower. At least one of mixed C4, normal C4, isomeric C4 and liquefied gas is used as the absorbent at the top of the absorption tower to obtain the gas phase at the top of the absorption tower and the liquid phase at the bottom of the absorption tower. The liquid phase at the bottom of the absorption tower is returned to be mixed with the sulfur-free rich gas (S-6) for gas-liquid equilibrium; (9) C3 / C4 separation: The liquid phase at the bottom of separator IV is further separated by a demethanizer (25) and a depropanizer (26) to obtain an ethane-rich gas product (S-11) and a mixed C4 product (S-10); (10) Reabsorption: The gas phase at the top of the absorption tower is sent to the reabsorption tower (27) to recover C3 and components above C3, and another part of the stabilized naphtha is used as a reabsorbent. The gas phase at the top of the reabsorption tower is produced as dry gas (S-12), and the liquid phase at the bottom of the reabsorption tower is returned to the stabilization tower (1); When only the liquefied gas component is recovered, the liquefied gas component recovery system is opened, the control valves of the intermediate reboiler and the bottom reboiler of the demethanizer are closed, and the control valve of the LPG reboiler in the intermediate of the demethanizer is opened, including the following steps: (11) By adjusting the system for recovering liquefied gas components, closing the membrane separation tail gas control valve (V2) and the PSA tail gas control valve (V3), stopping the operation of the third raw gas compressor (13), opening the cross-line control valve (V1), closing the absorption tower air inlet control valve (V7), and using the naphtha component steam at the bottom of the depropanizer as the heat source for the LPG reboiler in the middle of the demethanizer; the liquid phase at the bottom of the separator IV enters the demethanizer (25) and the depropanizer (26) for further separation to obtain a liquefied gas product (S-11LPG) and a naphtha component (S-10LPG); (12) Reabsorption: The gas phase at the top of the separator IV is sent to the reabsorption tower (27) to recover C3 and components above C3. The gas phase at the top of the reabsorption tower is extracted as dry gas (S-12), and the liquid phase at the bottom of the reabsorption tower is returned to the stabilization tower (1).

2. The comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components according to claim 1, wherein: When only the liquefied gas component is recovered, the following steps are also included: opening the control valve (V8) from the demethanizer to the second raw gas compressor, closing the circulating light hydrocarbon control valve (V4), the light hydrocarbon control valve at the bottom of the absorption tower (V5) and the control valve (V6) from the absorption tower to the reabsorption tower.

3. The comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components 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 operating temperature of the stabilization tower reflux tank 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 desulfurization and demercaptan tower is 35-45° C., and the operating pressure is 3.0-5.0 MPaG.

4. The comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components 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; Another portion of the stabilized naphtha was used as a reabsorbent (S-13).

5. The comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components 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 absorption tower is 2.0-4.0 MPag.

6. The comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components according to claim 1, wherein: The liquid phase at the bottom of the liquid tank IV enters the demethanizer, and the gas phase at the top of the demethanizer is returned to mix with the PSA tail gas, and the gas phase is pressurized III. The liquid phase at the bottom of the demethanizer is sent to the depropanizer, and an ethane-rich gas product is obtained at the top of the tower, and a mixed C4 product is obtained at the bottom of the tower; The mixed C4 product is partially used as a C4-depleted absorbent circulating at the top of the absorption tower.

7. The comprehensive recovery method for saturated light hydrocarbons with flexible adjustment of recovery components according to claim 5, wherein: The top pressure of the demethanizer is 1.0-1.5 MPag; The top pressure of the depropanizer is 1.4-2.0 MPag.

8. A comprehensive recovery device for saturated light hydrocarbons with flexible adjustment of recovery components, characterized in that: The device comprises: a mixed naphtha feed line, a hydrofining sulfur-rich gas feed line, a PSA tail gas feed line, a hydrocracking membrane separation tail gas feed line, a stabilizing tower (1), a first raw gas compressor (10), a cooler I (11), a liquid separator I (12), a second raw gas compressor (4), a cooler II (5), a liquid 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 third raw gas compressor (13), a cooler III (14), a liquid separator III (15), a crude hydrocarbon pump III (16), a shallow cooler I (17), a shallow cooler II (18), a liquid separator IV (23), an absorption tower (24), a demethanizer (25), a depropanizer (26), a reabsorption tower (27), and a liquefied gas recovery system; The hydrofining sulfur-rich gas feed pipeline is connected to the first raw gas compressor (10), the cooler I (11) and the liquid separator I (12) in sequence, and the liquid separator I (12) is provided with a liquid separator I tank top discharge pipeline and a liquid separator I tank bottom discharge pipeline; The mixed naphtha feed pipeline, the liquid separator tank 1 top discharge pipeline and the liquid separator tank 1 bottom discharge pipeline are connected to the stabilization tower (1). The stabilization tower (1) 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. The upper part of the stabilization tower is also provided with a condenser, a stabilization tower reflux tank (2) and a stabilization tower reflux pump (3). The stabilization tower top discharge pipeline is connected to the condenser and the stabilization tower reflux tank (2) in sequence. The stabilization tower reflux tank (2) 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 (4), the cooler II (5) and the liquid separator II (6) in sequence, and the liquid separator II (6) is provided with a top discharge pipeline of the liquid separator II and a bottom discharge pipeline of the liquid separator II; The discharge pipeline at the top of the liquid separator II is connected to the superheater (8) and the gas phase desulfurization tower (9) in sequence, and the gas phase desulfurization tower (9) is provided with a gas phase desulfurization tower discharge pipeline; After the stabilization tower reflux tank bottom discharge pipeline is connected to the stabilization tower reflux pump (3), it is divided into two branches, one of which is connected to the desulfurization and demercaptan tower (19), and the separation tank II tank bottom discharge pipeline is sequentially connected to the crude hydrocarbon pump II (7) and the desulfurization and demercaptan tower (19), and the desulfurization and demercaptan tower (19) is provided with a desulfurization and demercaptan tower discharge pipeline; The PSA tail gas feed pipeline is connected to the third raw gas compressor (13), the cooler III (14) and the liquid separator III (15) in sequence, and the liquid separator III (15) is provided with a liquid separator III tank top discharge pipeline and a liquid separator III tank bottom discharge pipeline; the PSA tail gas feed pipeline is provided with a PSA tail gas control valve (V3); The discharge pipeline from the top of the liquid separator III, the feed pipeline for the hydrocracking membrane separation tail gas and the discharge pipeline for the gas phase desulfurization tower are combined into a sulfur-free rich gas pipeline, which is then sequentially connected to the shallow cooler I (17) and the liquid separator IV (23). The liquid separator IV (23) is provided with a discharge pipeline from the top of the liquid separator IV and a discharge pipeline from the bottom of the liquid separator IV. The feed pipeline for the hydrocracking membrane separation tail gas is provided with a membrane separation tail gas control valve (V2). The discharge pipeline from the top of the liquid separator IV is divided into two branches, one of which is connected to the absorption tower (24) and is provided with an absorption tower air intake control valve (V7), and the other is connected to the reabsorption tower (27) and is provided with a cross-line control valve (V1); The bottom discharge pipeline of the liquid separator III is connected to the crude hydrocarbon pump III (16), and then merged with the discharge pipeline of the desulfurization and demercaptan tower, and then sequentially connected to the shallow cooler II (18) and the middle part of the absorption tower. The absorption tower (24) is provided with an absorption tower top discharge pipeline and an absorption tower bottom discharge pipeline, and the absorption tower bottom discharge pipeline merges with the sulfur-free rich gas pipeline; The bottom discharge pipeline of the separator IV is connected to the demethanizer (25) and the depropanizer (26). The demethanizer (25) is provided with a demethanizer intermediate reboiler, a demethanizer intermediate LPG reboiler, a demethanizer bottom reboiler and a demethanizer top discharge pipeline. The demethanizer top discharge pipeline is divided into two branches, one of which merges with the PSA tail gas feed pipeline; the demethanizer intermediate reboiler, the intermediate LPG reboiler and the demethanizer bottom reboiler are all provided with control valves; The absorption tower top discharge pipeline is connected to the reabsorption tower (27), and the reabsorption tower (27) is provided with a reabsorption tower top discharge pipeline and a reabsorption tower bottom discharge pipeline, and the reabsorption tower bottom discharge pipeline is connected to the middle of the stabilization tower; The cross-line control valve (V1), the membrane separation tail gas control valve (V2), the PSA tail gas control valve (V3), and the absorption tower air inlet control valve (V7) are connected to the liquefied gas recovery system.

9. The saturated light hydrocarbon comprehensive recovery device with flexible adjustment of recovery components 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; another discharge line from the bottom of the stabilization tower is connected to the reabsorption tower (27); Another discharge pipeline from the bottom of the stabilization tower reflux tank is connected to the upper part of the stabilization tower.

10. The saturated light hydrocarbon comprehensive recovery device with flexible adjustment of recovery components according to claim 8, wherein: The absorption tower bottom discharge pipeline is provided with an absorption tower bottom light hydrocarbon control valve (V5); Another demethanizer top discharge pipeline merges with the stabilization tower reflux tank top discharge pipeline, and a demethanizer to second raw gas compressor control valve (V8) is provided on the pipeline; The depropanizer (26) is provided with a depropanizer top discharge pipeline and a depropanizer bottom discharge pipeline, the depropanizer bottom discharge pipeline is divided into two branches, one of which is connected to the upper part of the absorption tower, and a circulating light hydrocarbon control valve (V4) is provided on the pipeline; The absorption tower top discharge pipeline is provided with an absorption tower to reabsorption tower control valve (V6); The circulating light hydrocarbon control valve (V4), the light hydrocarbon control valve at the bottom of the absorption tower (V5), the control valve from the absorption tower to the reabsorption tower (V6), and the control valve from the demethanizer to the second raw gas compressor (V8) are connected to the liquefied gas recovery system.

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