Ethylene glycol regeneration and recovery system based on electrodialysis desalination technology

Abstract

The present application relates to a kind of glycol regeneration and recovery system based on electrodialysis desalination technology, belong to oil and gas exploitation technical field, applied to offshore oil and gas field and future natural gas hydrate exploitation.Its technical points are: including pretreatment unit, electrodialysis unit, double-effect evaporation unit, auxiliary system, vacuum unit, each part is connected by corresponding pipeline, constitute a kind of based on electrodialysis desalination, double-effect evaporation technology offshore natural gas hydrate exploitation glycol regeneration and recovery system, the present application introduces glycol electrodialysis desalination monovalent salt technology, glycol double-effect evaporation dehydration technology, auxiliary system self-circulation salt balance technology, with the advantages of environmental protection, low energy consumption, small volume, flexible arrangement, low operating cost.

Description

Technical Field

[0001] This invention relates to an ethylene glycol regeneration and recovery system based on electrodialysis desalination technology, belonging to the field of oil and gas extraction technology, and applied to offshore oil and gas fields and future natural gas hydrate extraction. Background Technology

[0002] Considering economic, environmental, and safety factors, ethylene glycol dehydration and desalination are commonly used in offshore oil and gas field development and future natural gas hydrate development, and the glycol is recycled after meeting standards.

[0003] Traditional marine ethylene glycol regeneration and recovery (MRU) systems primarily employ a split desalination process, comprising three treatment units: a pretreatment unit, a regeneration unit, and a desalination unit. The working process is as follows:

[0004] The ethylene glycol-rich solution undergoes a pretreatment unit to remove liquid / gas-state hydrocarbons and acidic gases such as CO2; then, Na2CO3 and NaOH solutions are added to react with divalent salts (Ca) in the ethylene glycol-rich solution. 2+ Mg 2+ A chemical reaction occurs, producing insoluble divalent salts such as CaCO3 and MgOH2. The insoluble divalent salt particles are separated by a particle filter, made into salt cakes, and transported to land periodically.

[0005] The pretreated ethylene glycol-rich solution is introduced into the regeneration unit distillation column. Inside the distillation column, the ethylene glycol-rich solution is continuously heated to a temperature above the boiling point of water, causing the water to evaporate into steam. The steam is then introduced into a condenser for condensation and cooling, and the cooled condensate enters the platform's production water system. After the water in the ethylene glycol-rich solution in the distillation column is evaporated, the ethylene glycol concentration increases to meet the requirements, forming a lean ethylene glycol solution which is then discharged.

[0006] After dehydration in the regeneration unit, a portion of the lean ethylene glycol solution is introduced into a desalting distillation column, where it is further heated to above the boiling point of ethylene glycol. Ethylene glycol and a small amount of water form a mixed vapor, which is then introduced into a condenser for condensation and cooling. This mixed vapor is then mixed with another portion of the unevaporated lean ethylene glycol solution to meet production requirements and pumped into a storage tank for recycling. Inside the distillation column, as ethylene glycol and water continuously evaporate, the concentration of monovalent salts at the bottom of the column gradually increases, initiating crystallization. The crystals are introduced into a centrifuge to separate residual ethylene glycol and water, which are then reinjected into the distillation column. The separated monovalent salt crystals are exported and temporarily stored on a platform for periodic transport back to land for further processing.

[0007] The existing system process has the following limitations:

[0008] 1. High heating and cooling loads

[0009] The existing process system's regeneration and desalination units consume a large amount of cold / heat energy to heat water and ethylene glycol for evaporation and condensation, thereby achieving the separation of water from ethylene glycol and ethylene glycol from salt.

[0010] 2. It is necessary to continuously replenish the alkali and transport the monovalent and divalent salts to land for processing.

[0011] The pretreatment process requires the addition of alkali to precipitate and remove divalent salts through filtration. The desalination process will produce some monovalent salt crystals. Therefore, it is necessary to continuously add alkali and generate salt. Solid salt and solid alkali need to be frequently transported between the platform and the land to maintain the normal operation of the platform. This has certain limitations for the practical application of independent offshore platforms.

[0012] 3. The equipment is large and complex, making it difficult to operate. Summary of the Invention

[0013] To address the shortcomings of existing technologies, this invention introduces ethylene glycol electrodialysis for removing monovalent salts, ethylene glycol double-effect evaporation for dehydration, and an auxiliary system for self-circulating salt balance. A system for the regeneration and recovery of ethylene glycol in offshore natural gas hydrate extraction based on electrodialysis desalination and double-effect evaporation technologies is developed, offering advantages such as low energy consumption and high economic efficiency.

[0014] To achieve the above objectives, the technical solution of the present invention is: an ethylene glycol regeneration and recovery system based on electrodialysis desalination technology, comprising a pretreatment unit, an electrodialysis unit, a double-effect evaporation unit, an auxiliary system, and a vacuum unit; characterized in that: one end of the pretreatment unit is connected to an inlet pipe, and through a pipe, it is connected to a platform, the electrodialysis unit, the auxiliary system, and the vacuum unit; the electrodialysis unit is connected to the platform and the double-effect evaporation unit through a pipe; one end of the double-effect evaporation unit is connected to a pipe, and through a pipe, it is connected to the vacuum unit and the auxiliary system; the auxiliary system is connected to the platform through a pipe; the vacuum unit is connected to the platform through a pipe.

[0015] The pretreatment unit includes a three-phase flash separation tank, an alkali buffer tank, a divalent salt pre-coating filter device, a perlite batching tank, a pH adjustment tank, a feed heater, an ethylene glycol rich liquor transfer pump, a pre-coating transfer pump, and an ethylene glycol rich liquor booster pump; the various parts are connected by corresponding pipelines; its functions are: three-phase flash evaporation process, alkali chemical injection process, and acid pH adjustment process.

[0016] The electrodialysis unit uses a special electrodialysis unit, with 6 groups connected in parallel and 3 units in series in each group. The electrodialysis units are connected to each other through corresponding pipelines. The electrodialysis unit includes a desalination chamber and a concentration chamber.

[0017] The double-effect evaporation unit adopts a double-effect continuous distillation process, and two sets of double-effect dehydration units work in parallel, including: a first-effect recovery tower, a second-effect recovery tower, a first-effect evaporation flash tank, a waste gas flash tank, a recovered freshwater receiving tank, a first-stage feed preheater, a second-stage feed preheater, a first-effect recovery tower reboiler, a second-effect recovery tower reboiler, a recovered freshwater condenser, an ethylene glycol lean liquor cooler, a first-effect recovery tower circulation pump, a high-temperature recovered freshwater transfer pump, a second-effect recovery tower circulation pump, an ethylene glycol lean liquor transfer pump, and a recovered freshwater transfer pump. Each part is connected by corresponding pipelines.

[0018] The auxiliary system includes a freshwater recovery buffer tank, a hydrochloric acid buffer tank, a sodium hydroxide solution buffer tank, a sodium carbonate / sodium hydroxide buffer tank, a monovalent salt dissolving tank, a divalent salt dissolving tank, a mixed alkali reaction tank, an alkali concentration tank, a bipolar membrane electrodialysis unit, an alkali evaporation water condenser, a concentrated alkali transfer pump, and an alkali transfer pump. The various parts are connected by corresponding pipelines.

[0019] The vacuum unit mainly includes a vacuum pump system and a hydrocarbon-containing waste gas condensation and recovery system, which consists of a vacuum buffer tank, a tail gas condenser, a vacuum unit, and a tail gas phase separation tank.

[0020] By adopting the above technical solutions, the present invention has the following advantages and effects:

[0021] 1. Low energy consumption and environmentally friendly

[0022] Traditional distillation desalination requires heating the solution above its boiling point, consuming a large amount of energy. This system desalinates at room temperature, significantly reducing energy consumption and greenhouse gas emissions, making it environmentally friendly.

[0023] Although the investment required for the dual-effect evaporation dehydration technology is slightly increased, it can reduce energy consumption by about 50%, is flexible in operation, has good economic efficiency, and is environmentally friendly.

[0024] 2. Employ salt balance technology to achieve self-circulating salt balance.

[0025] Sodium carbonate and sodium hydroxide are added during the removal of divalent salts, forming divalent salt precipitates and sodium chloride. The sodium chloride formed in the reaction is converted into hydrochloric acid through bipolar membrane electrodialysis. This hydrochloric acid reacts with the divalent salt precipitate to restore the original form of the divalent salt before it is discharged into the sea. Simultaneously, the bipolar membrane electrodialysis produces a sodium hydroxide solution, which reacts with the carbon dioxide generated from the divalent salt precipitate reaction to produce a mixed alkaline solution of sodium carbonate and sodium hydroxide, which is recycled to achieve a self-circulating salt balance. This significantly reduces the transportation of acid and alkali reagents and divalent salt filter cake between the land and the platform, improving the independence of platform operation.

[0026] 3. The system is relatively small in size and flexible in layout.

[0027] The system is lightweight and occupies little space. The electrodialysis unit can be laid flat or arranged vertically. It has good adaptability in layout and installation.

[0028] 4. The system solution has low energy consumption and low operating costs, and has good economic efficiency. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the preprocessing unit structure of the present invention;

[0031] Figure 3 This is a schematic diagram of the electrodialysis unit structure of the present invention;

[0032] Figure 4 This is a schematic diagram of the working principle of the electrodialysis unit of the present invention;

[0033] Figure 5 This is a schematic diagram of the dual-effect evaporation and dehydration unit structure of the present invention;

[0034] Figure 6 This is a schematic diagram of the auxiliary system structure of the present invention;

[0035] Figure 7 This is a schematic diagram of the vacuum unit structure of the present invention; Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the accompanying drawings:

[0037] An ethylene glycol regeneration and recovery system based on electrodialysis desalination technology, such as Figure 1 As shown, it includes a pretreatment unit 1, an electrodialysis unit 2, a double-effect evaporation unit 3, an auxiliary system 4, and a vacuum unit 5; characterized in that: one end of the pretreatment unit 1 is connected to the inlet pipe 6-1, and it is connected to the platform through pipes 6-13, 6-17, and 6-23; it is connected to the electrodialysis unit 2 through pipe 6-2; it is connected to the auxiliary system 4 through pipes 6-10, 6-11, and 6-12; and it is connected to the vacuum unit 5 through pipe 6-14; the electrodialysis unit 5... Unit 2 is connected to the platform via pipes 6-21 and 6-3, and to the double-effect evaporation unit 3 via pipe 6-4; one end of the double-effect evaporation unit 3 is connected to pipe 6-6, and to the vacuum unit 5 via pipes 6-5, 6-18, and 6-22, and to the auxiliary system 4 via pipe 6-7; the auxiliary system 4 is connected to the platform via pipes 6-8, 6-9, 6-16, 6-19, and 6-20; the vacuum unit 5 is connected to the platform via pipe 6-15.

[0038] The preprocessing unit 1 is as follows Figure 2As shown, it includes a three-phase flash separation tank V01, an alkali buffer tank V02, divalent salt pre-coating filter devices V03A and V03B, a perlite batching tank V04, a pH adjustment tank V05, a feed heater E01, an ethylene glycol rich liquor transfer pump P01, a pre-coating transfer pump P02, and an ethylene glycol rich liquor booster pump P03; the various parts are connected by corresponding pipelines; its functions are: three-phase flash evaporation process, alkali chemical injection process, and acid addition pH adjustment process;

[0039] The electrodialysis unit 2 is as follows Figure 3 , 4 As shown, special electrodialysis units X01-X03 are used, with 6 groups connected in parallel and 3 units in series in each group. The electrodialysis units are connected to each other through corresponding pipelines. The electrodialysis unit includes: desalination chamber 7 and concentration chamber 8.

[0040] The dual-effect evaporation unit 3, as described above Figure 5 As shown, a double-effect continuous distillation process is adopted, with two sets of double-effect dehydration units operating in parallel, including: a first-effect recovery tower T01, a second-effect recovery tower T02, a first-effect evaporation flash tank V06, a waste gas flash tank V07, a recovered freshwater receiving tank V08, a first-stage feed preheater E02, a second-stage feed preheater E03, a first-effect recovery tower reboiler E04, a second-effect recovery tower reboiler E05, a recovered freshwater condenser E06, an ethylene glycol lean liquor cooler E07, a first-effect recovery tower circulation pump P04, a high-temperature recovered freshwater transfer pump P05, a second-effect recovery tower circulation pump P06, an ethylene glycol lean liquor transfer pump P07, and a recovered freshwater transfer pump P08. Each part is connected by corresponding pipelines.

[0041] The auxiliary system 4, as Figure 6 As shown, the system includes a freshwater recovery buffer tank V12, a hydrochloric acid buffer tank V13, a sodium hydroxide solution buffer tank V14, a sodium carbonate / sodium hydroxide buffer tank V15, a monovalent salt dissolving tank V16, a divalent salt dissolving tank V17, a mixed alkali reaction tank V18, an alkali concentration tank V19, a bipolar membrane electrodialysis unit M02, an alkali evaporation water condenser E14, a concentrated alkali transfer pump P14, and an alkali transfer pump P15. The components are connected by corresponding pipelines.

[0042] The vacuum unit 5 is as follows Figure 7 As shown, it mainly includes a vacuum pump system and a hydrocarbon-containing waste gas condensation and recovery system, which consists of a vacuum buffer tank V20, a tail gas condenser E15, a vacuum unit M04, and a tail gas phase separation tank V21.

[0043] Its working process is as follows:

[0044] 1. The working process of preprocessing unit 1 is as follows: Figure 2 As shown:

[0045] Ethylene glycol rich liquor three-phase separation process: The ethylene glycol rich liquor enters the pretreatment unit 1 through pipeline 6-1, and after being heated by the feed heater E01, it enters the three-phase flash separator V01. The three-phase flash separator V01 is filled with phase-separating packing internals. After phase separation, the gas phase is discharged to the vacuum unit 5 through pipeline 6-14, and then discharged for combustion treatment through pipeline 6-15. The oil phase, rich in hydrocarbons, is discharged to the platform through pipeline 6-23. The ethylene glycol rich liquor (aqueous phase) is discharged from the three-phase flash separator V01, and then sodium carbonate and sodium hydroxide alkaline solutions are continuously added and stirred in the alkali buffer tank V02. The reaction produces divalent salt precipitates (CaCO3, FeCO3, Mg(OH)2), which are pressurized by the ethylene glycol rich solution transfer pump P01 and then filtered through the divalent salt pre-coated filter devices V03A and V03B. The divalent salt filter cake in the filter devices is backflushed with nitrogen and then sent to the auxiliary system 4 through pipeline 6-11. After the divalent salts are removed, the ethylene glycol rich solution is continuously added with dilute hydrochloric acid through pipeline 6-13 and stirred evenly in the pH adjustment tank V05. After adjusting the pH to about 8, it is sent to the electrodialysis unit 2 through the ethylene glycol rich solution booster pump P03 and pipeline 6-2.

[0046] Regeneration process of divalent salt pre-coated filter devices V03A and V03B: The two divalent salt pre-coated filter devices V03A and V03B work alternately, with program control and automatic switching. Perlite is stirred evenly in perlite mixing tank V04, and then circulated between mixing tank V04 and divalent salt pre-coated filter devices V03A and V03B through pre-coating transfer pump P02 to regenerate the pre-coated layer.

[0047] 2. The working process of electrodialysis unit 2 is as follows: Figure 3 , 4 As shown:

[0048] After being treated by the pretreatment unit 1, the high-salt ethylene glycol-rich solution enters the desalination chamber 7 of the electrodialysis unit 2 through pipeline 6-2. Seawater enters the concentration chamber 8 of the electrodialysis unit 2 from the platform through pipeline 6-21. The desalination chambers 7 and concentration chambers 8 of each stage of the electrodialysis unit are connected sequentially by corresponding pipelines. The low-salt ethylene glycol-rich solution obtained at the end of the electrodialysis unit 2 enters the double-effect evaporation unit 3 through pipeline 6-4, while the concentrated seawater is directly discharged into the sea through pipeline 6-3.

[0049] 3. The working process of the double-effect evaporation unit 3 is as follows: Figure 5 As shown:

[0050] The low-salt ethylene glycol-rich solution from electrodialysis unit 2 is preheated successively by the primary feed preheater E02 and the secondary feed preheater E03 before entering the first-effect recovery tower T01. The circulating pump P04 of the first-effect recovery tower pumps the ethylene glycol-rich solution from the bottom of the tower and delivers it to the reboiler E04 of the first-effect recovery tower, which uses steam as a heat source, forming a heating cycle. The ethylene glycol-rich solution, after partial water removal, enters the second-effect recovery tower T02.

[0051] The reboiler E05 of the second-effect recovery tower uses the water vapor evaporated from T01 of the first-effect recovery tower as a heat source, and establishes a heating cycle through the second-effect recovery tower circulation pump P06. In the second-effect recovery tower T02, some water is further removed. The dehydrated ethylene glycol lean liquor meets the process requirements and is then transported to the ethylene glycol lean liquor tank on the platform for later use via the ethylene glycol lean liquor transfer pump P07, the ethylene glycol lean liquor cooler E07, and pipeline 6-6. The ethylene glycol lean liquor cooler E07 uses seawater cooling.

[0052] The water vapor generated by the first-effect recovery tower T01 is first condensed and heat-exchanged in the reboiler E05 of the second-effect recovery tower, and then enters the first-effect evaporation flash tank V06 to remove residual light hydrocarbons. It is then discharged to the vacuum unit 5 through pipeline 6-18, and then further depressurized into the waste gas flash tank V07. The high-temperature fresh water in the waste gas flash tank V07 is sent to the first-stage feed preheater E02 through the high-temperature recovered fresh water transfer pump P05 to preheat the low-salt ethylene glycol rich liquid. Finally, it is collected and recycled through the recovered fresh water receiving tank V08.

[0053] The water vapor generated by the two-effect recovery tower T02 and the water vapor generated by the waste gas flash tank V07 are condensed into water by the condenser E06 and then enter the fresh water receiving tank V08 for collection and recycling.

[0054] The waste gas flash evaporator V07 and the recycled fresh water receiving tank V08 are connected to the vacuum unit 5 through pipeline 6-5 to form a vacuum.

[0055] The water removed by the double-effect recovery tower is collected, pressurized by the fresh water transfer pump P08, and enters the auxiliary system 4 through pipeline 6-7;

[0056] 4. The working process of auxiliary system 4 is as follows: Figure 6 As shown:

[0057] Freshwater from the double-effect evaporation unit 3 enters the freshwater recovery buffer tank V12 through pipelines 6-7. A small amount is used as reflux for double-effect continuous distillation and enters the sodium chloride dissolving tank V16 of the auxiliary system 4. A large amount of surplus freshwater is discharged to the platform through pipelines 6-8 of the auxiliary system 4 for use as production water or discharged into the sea.

[0058] Sodium chloride crystals are introduced into the monovalent salt dissolving tank V16 through pipelines 6-9; in the monovalent salt dissolving tank V16, the externally added sodium chloride crystal particles are mixed with a certain amount of production water to form a sodium chloride solution of a certain concentration, which is then sent to the bipolar membrane electrodialysis unit M02.

[0059] Bipolar membrane electrodialysis process: A sodium chloride solution of a certain concentration undergoes ion recombination to form hydrochloric acid solution and sodium hydroxide solution of a certain concentration; the hydrochloric acid solution is introduced into hydrochloric acid buffer tank V13, a portion of which enters divalent salt dissolving tank V17, and the remainder enters hydrochloric acid storage tank on the platform through pipeline 6-19; the sodium hydroxide solution is introduced into alkali concentration tank V19, and after evaporation and concentration, it is sent to sodium hydroxide solution buffer tank V14 through mixed alkali transfer pump P15, a portion of which enters mixed alkali reaction tank V18 for alkali production, and the remainder enters sodium hydroxide solution storage tank on the platform through pipeline 6-20; the water vapor evaporated from the sodium hydroxide solution in alkali concentration tank V19 is cooled and condensed by alkali evaporation water condenser E14, and then mixed with surplus fresh water in recovery fresh water buffer tank V12 and discharged to the platform through pipeline 6-8 for use as production water or for discharge into the sea;

[0060] The divalent salt filter cake (CaCO3, Mg(OH)2) from pretreatment unit 1 is introduced into the divalent salt dissolving tank V17 via pipeline 6-11. There, it reacts with the hydrochloric acid solution from hydrochloric acid buffer tank V13 to produce soluble divalent salts (CaCl2, MgCl2), carbon dioxide (CO2), and water (H2O). The carbon dioxide (CO2) gas is sent to the mixed alkali reaction tank V18 for alkali production. Insufficient carbon dioxide (CO2) is replenished via pipeline 6-16.

[0061] The divalent salt solution after the reaction in the divalent salt dissolving tank V17 contains a small amount of perlite. After centrifugal filtration, the divalent salt solution is mixed with the water condensed from the alkali concentration tank V19 and discharged to the platform through pipeline 6-8 for use as production water or for discharge into the sea. The perlite is returned to the pretreatment unit 1 for recycling through pipeline 6-10.

[0062] Sodium hydroxide solution from sodium hydroxide solution buffer tank V14 reacts with carbon dioxide in mixed alkali reaction tank V18, and part of the reaction produces sodium carbonate. The sodium carbonate and sodium hydroxide alkali concentrations are adjusted by heating and evaporation, and then pumped into buffer tank V15 through concentrated alkali transfer pump P14. It is then sent to pretreatment unit 1 for reuse through pipeline 6-12.

[0063] 5. The working process of vacuum unit 5 is as follows: Figure 7 As shown:

[0064] Both the pretreatment unit 1 and the double-effect evaporation unit 3 require a certain vacuum level to be maintained by the vacuum system 5. The pretreatment unit 1 and the double-effect evaporation unit 3 will continuously generate hydrocarbon-containing non-condensable gases. The pretreatment unit 1 is connected to the vacuum main pipe and the vacuum buffer tank V20 through the pipeline 6-14 and the double-effect evaporation unit 3 is connected to the vacuum buffer tank V20 through the pipeline 6-5. After being pressurized by the vacuum unit M04, the outlet becomes slightly positive pressure. It is mixed with the exhaust gas from the double-effect evaporation unit 3 through the pipeline 6-18 and sent to the tail gas condenser E15. After being condensed to a certain temperature, it enters the tail gas phase separator V21. In the tail gas phase separator V21, gas-liquid separation is achieved, and water and ethylene glycol are recovered. The gas is sent back to the waste gas flash tank V07 of the double-effect evaporation unit 3 through the pipeline 6-22. The hydrocarbon-containing non-condensable gases are discharged through the pipeline 6-15 for combustion treatment.

Claims

1. An ethylene glycol regeneration and recovery system based on electrodialysis desalination technology, comprising a pretreatment unit (1), an electrodialysis unit (2), a double-effect evaporation unit (3), an auxiliary system (4), and a vacuum unit (5); characterized in that: The pretreatment unit (1) is connected to the inlet pipe (6-1) at one end, and to the platform through pipes (6-13), (6-17), and (6-23). ​​It is connected to the electrodialysis unit (2) through pipe (6-2), to the auxiliary system (4) through pipes (6-10), (6-11), and (6-12), and to the vacuum unit (5) through pipe (6-14). The electrodialysis unit (2) is connected to the platform through pipes (6-21) and (6-3), and to the double-effect evaporation unit (3) through pipe (6-4). The double-effect evaporation unit (3) is connected to the pipe (6-6) at one end, and to the vacuum unit (5) through pipes (6-5), (6-18), and (6-22). It is connected to the vacuum unit (5) through pipe (6-7). Connected to the auxiliary system (4); the auxiliary system (4) is connected to the platform via pipelines (6-8), (6-9), (6-16), (6-19), (6-20); the vacuum unit (5) is connected to the platform via pipeline (6-15); the pretreatment unit (1) includes a three-phase flash separation tank (V01), an alkali buffer tank (V02), a divalent salt pre-coating filter device (V03A), (V03B), a perlite batching tank (V04), a pH adjustment tank (V05), a feed heater (E01), an ethylene glycol rich liquor transfer pump (P01), a pre-coating transfer pump (P02), and an ethylene glycol rich liquor booster pump (P03); each part is connected via corresponding pipelines; the electrodialysis unit (2) uses a special electrodialysis device ( X01-X03), 6 groups in parallel, 3 units in series in each group, and each electrodialysis unit is connected by corresponding pipelines; the electrodialysis unit includes: desalination chamber (7) and concentration chamber (8); the double-effect evaporation unit (3) adopts double-effect continuous distillation process, and 2 groups of double-effect dehydration units work in parallel, including first-effect recovery tower (T01), second-effect recovery tower (T02), first-effect evaporation flash tank (V06), waste gas flash tank (V07), recovered freshwater receiving tank (V08), first-stage feed preheater (E02), second-stage feed preheater (E03), first-effect recovery tower reboiler (E04), second-effect recovery tower reboiler (E05), recovered freshwater condenser (E06), ethylene glycol lean liquor cooler (E07), and first-effect recovery tower circulating pump (P04). The system includes a high-temperature freshwater recovery pump (P05), a double-effect recovery tower circulation pump (P06), an ethylene glycol lean solution transfer pump (P07), and a freshwater recovery pump (P08), all connected by corresponding pipelines. The auxiliary system (4) includes a freshwater recovery buffer tank (V12), a hydrochloric acid buffer tank (V13), a sodium hydroxide solution buffer tank (V14), a sodium carbonate / sodium hydroxide buffer tank (V15), a monovalent salt dissolving tank (V16), a divalent salt dissolving tank (V17), a mixed alkali reaction tank (V18), an alkali concentration tank (V19), a bipolar membrane electrodialysis unit (M02), an alkali evaporation water condenser (E14), a concentrated alkali transfer pump (P14), and an alkali transfer pump (P15), all connected by corresponding pipelines.The vacuum unit (5) mainly includes a vacuum pump system and a hydrocarbon-containing waste gas condensation and recovery system, consisting of a vacuum buffer tank (V20), a tail gas condenser (E15), a vacuum unit (M04), and a tail gas phase separation tank (V21).

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