A pre-washing methanol regeneration device and a pre-washing methanol regeneration method

Abstract

This application discloses a pre-wash methanol regeneration device and method. The device includes a pre-wash tower, a washing tower, a regeneration tower I, a methanol-water separation tower, a flash stripping system, and a regeneration tower II. The pre-wash tower, washing tower, flash stripping system, regeneration tower I, and methanol-water separation tower are sequentially connected by pipelines. The pre-wash tower is connected to the methanol-water separation tower by pipeline, and the regeneration tower II is connected to the pre-wash tower, regeneration tower I, and methanol-water separation tower by pipeline. Regeneration tower II regenerates the pre-washed methanol separately. The generated acidic gas containing impurities is produced in small quantities and does not require cooling before desulfurization recovery, avoiding impurity accumulation and discharging impurities from the system with minimal methanol loss, ensuring purification standards. The methanol-water separated by the pre-wash tower is flash-evaporated by heat exchange and then enters the methanol-water separation tower. The pre-washed methanol-rich methanol, which is anhydrous, is returned to regeneration tower I after regeneration by regeneration tower II. The regeneration tower I can eliminate the water concentration section. This design ensures a low water content in the system.

Description

Technical Field

[0001] This application relates to a pre-wash methanol regeneration device and a pre-wash methanol regeneration method, which belongs to the field of coal chemical industry. Background Technology

[0002] The feed gas from coal chemical plants often contains acidic gases such as CO2 and H2S. These gases need to be removed by low-temperature methanol washing to obtain purified syngas that meets downstream requirements. Low-temperature methanol washing is a physical absorption method that utilizes the high solubility and selectivity of methanol for acidic gases such as CO2 and H2S at low temperatures (-70 to -30°C). Using methanol as a solvent, it removes acidic gases from the feed gas and has advantages such as strong absorption capacity, high purification efficiency, and good selectivity. It is widely used in modern large-scale coal chemical plants.

[0003] Low-temperature methanol washing absorbs and removes acidic media such as CO2, H2S, and COS from the feed gas, yielding purified gas. The absorbed H2S and COS can be sent to a sulfur recovery unit as acidic gas, while some of the CO2 can be used as a product, and a portion is emitted as tail gas along with stripped nitrogen. Low-temperature methanol washing typically requires the sulfur content in the purified gas to be less than 0.1 ppm, and the total sulfur content in the CO2 product gas to be less than 5 mg / Nm³. 3 Environmental standards also have requirements for the sulfide content in exhaust gases.

[0004] Due to the influence of the preceding process conditions and operating conditions, the raw gas for methanol washing often contains impurities such as ammonia, methanethiol, and ethanethiol, in addition to acidic media such as CO2, H2S, and COS. These impurities accumulate in the system, affecting the quality of lean methanol, and consequently causing the total sulfur content in the purified gas, CO2 product gas, and tail gas to exceed the standard.

[0005] The accumulation of impurities has caused excessive sulfur content in the purified gas, CO2 product gas, and tail gas of several low-temperature methanol washing units. To remove impurities and reduce accumulation, the current solutions are: Solution 1 is to discharge the contaminated methanol liquid, and Solution 2 is to not cool the acidic gas, which will carry methanol and impurities out with it due to its higher temperature. Both solutions will result in a significant loss of methanol. More importantly, the sulfur-containing contaminated methanol discharged by Solution 1 cannot be treated and recovered, which can easily cause environmental pollution; Solution 2, due to the high methanol content in the acidic gas, seriously affects the normal operation of downstream sulfur recovery.

[0006] Therefore, a feasible solution is needed that minimizes methanol loss and has minimal impact on the environment or downstream processes, in order to address the accumulation of impurities such as ammonia, methanethiol, and ethanethiol in the low-temperature methanol washing system and ensure that the total sulfur in the purified gas, CO2 product gas, and tail gas meets the design requirements. Summary of the Invention

[0007] According to one aspect of this application, a pre-wash methanol regeneration device is provided, which solves the problem of excessive sulfur content in purified gas, CO2 product gas and tail gas caused by the accumulation of impurities in the raw material gas in the low-temperature methanol washing system.

[0008] The pre-wash methanol regeneration unit includes a pre-wash tower, a washing tower, a regeneration tower I, a methanol-water separation tower, a flash stripping system, and a regeneration tower II;

[0009] The pre-washing tower, washing tower, flash stripping system, regeneration tower I, and methanol-water separator are connected in sequence by pipelines. The pre-washing tower is connected to the methanol-water separator by pipelines. The regeneration tower II is connected to the pre-washing tower, regeneration tower I, and methanol-water separator by pipelines.

[0010] The pre-washing tower is provided with outlet I-1 at the bottom, outlet I-2 at the top, and outlet I-3 on the side wall;

[0011] The washing tower has an inlet II-1 on its bottom sidewall, and the inlet II-1 is connected to the outlet I-2 pipeline;

[0012] The thermal regeneration tower I is provided with an outlet III-1 at the bottom and inlets III-1 and III-2 on the side wall of the tower.

[0013] The methanol-water separator is provided with inlet IV-1, inlet IV-2, outlet IV-1, and outlet IV-2. Inlet IV-1 is connected to outlet I-1 via pipeline, outlet III-1 is connected to inlet IV-2 via pipeline, and outlet IV-2 is connected to inlet III-1 via pipeline.

[0014] The regeneration tower II has an inlet V-1, an inlet V-2, and an outlet V-1 on its side wall; the inlet V-1 is connected to the outlet I-3 pipeline, the inlet V-2 is connected to the outlet IV-1 pipeline, and the outlet V-1 is connected to the inlet III-2 pipeline. The regeneration tower II also has a gas phase outlet I.

[0015] Optionally, the pre-wash methanol regeneration unit further includes a tail gas water washing tower;

[0016] The flash steam stripping system is connected to the tail gas washing tower pipeline.

[0017] Optionally, the pre-washing tower is provided with a water distribution section and a pre-washing section sequentially from the bottom to the top of the tower;

[0018] The outlet II-2 is located at the bottom of the pre-wash section.

[0019] Optionally, the scrubbing tower is provided with a desulfurization section and a decarbonization section from the bottom to the top of the tower.

[0020] The desulfurization section and the decarbonization section are respectively connected to the flash steam stripping system pipeline;

[0021] The decarbonization section is also connected to the pre-washing tower.

[0022] Optionally, the regeneration tower II is equipped with a reflux cooling device.

[0023] Optionally, the regeneration tower II is also provided with a methanol discharge outlet for discharging impurity-rich dirty methanol;

[0024] Optionally, the regeneration tower II is further provided with a nitrogen inlet II for inputting low-pressure nitrogen.

[0025] Optionally, the top of the regeneration tower I is provided with an outlet III-2;

[0026] The outlet III-2 is connected to the flash steam stripping system via a pipeline;

[0027] Optionally, a separation device II is also provided on the pipeline connecting the outlet III-2 to the flash stripping system;

[0028] The separation device II is also provided with a gas phase outlet II;

[0029] Optionally, a separation device I is provided on the pipeline connecting the outlet I-3 and the inlet V-1;

[0030] The separation device I is also provided with a gas phase outlet III;

[0031] Optionally, a separation device III is provided on the pipeline connecting the outlet I-1 and the inlet IV-1;

[0032] The separation device III is also provided with a gas phase outlet IV.

[0033] Optionally, the methanol-water separator is structurally optimized by adding a spare impurity discharge side stream.

[0034] Optionally, the device may also include several pumps, heat exchangers, etc., for the flow and heat exchange of gas and liquid throughout the device.

[0035] Another aspect of this application provides a pre-wash methanol regeneration method, in which a feed gas containing water, ammonia, methanethiol, and ethanethiol is separated into water and pre-washed, and the resulting pre-washed rich methanol is fed into the aforementioned pre-washed methanol regeneration device to achieve methanol regeneration.

[0036] Optionally, the method includes the following steps:

[0037] (1) The raw gas containing water, ammonia, methanethiol and ethanethiol is injected with a small amount of methanol, cooled and then enters the pre-washing tower. After water separation, condensate and raw gas I with a water content of 1 to 3 ppm are obtained. After pre-washing in the pre-washing section, raw gas II with an impurity content of less than 1 ppm and pre-washed methanol are obtained.

[0038] The condensate includes water and methanol;

[0039] Prewashing with methanol-rich materials includes methanol-rich materials, sulfur-containing compounds, and carbon-containing compounds;

[0040] (2) The condensate enters the methanol-water separation tower, and after separation, gaseous methanol and water are obtained;

[0041] The gaseous methanol enters the regeneration tower I, where it is regenerated to obtain acidic gaseous phase II and lean methanol;

[0042] The pre-washed methanol-rich gas enters regeneration tower II for regeneration, yielding aqueous methanol I and acidic gas;

[0043] The aqueous methanol I enters the regeneration tower I through inlet III-2, and is regenerated to obtain acidic gas phase II and lean methanol;

[0044] The lean methanol enters the methanol-water separator via inlet IV-2 to separate gaseous methanol and water.

[0045] (3) The raw material gas II enters the washing tower through inlet II-1 and is washed with lean methanol to obtain purified gas and rich methanol I. The rich methanol I enters the flash stripping system.

[0046] The purified gas includes H2 and CO.

[0047] Optionally, in step (2), the condensate is separated by separation device III and then enters the methanol-water separation tower;

[0048] The condensate is separated by separation device III to obtain acidic gas phase III;

[0049] Optionally, in step (2), the pre-washed methanol-rich material is separated by separation device I and then enters regeneration tower II;

[0050] The pre-washed methanol-rich material is separated by separation device I to obtain flash vapor I containing effective gases, which is then compressed and recovered. The effective gases include H2 and CO.

[0051] Optionally, in step (2), the acidic gas phase II is separated by separation device II to obtain acidic gas phase IV and methanol-rich II;

[0052] The methanol-rich II enters the flash stripping system.

[0053] As one specific embodiment, the pre-washed methanol regeneration device includes a washing tower, a thermal regeneration tower (i.e., regeneration tower I), a methanol-rich flash stripping system, a methanol-water separation tower, a tail gas washing tower, a pre-washed methanol regeneration tower (i.e., regeneration tower II), and a pre-washing tower.

[0054] The pre-washing tower is provided with a water separation section and a pre-washing section from bottom to top. The bottom outlet of the pre-washing tower is connected to the side wall inlet of the methanol-water separation tower via a methanol-water flash tank (i.e., separation device III). The outlet of the pre-washing section of the pre-washing tower is connected to the side wall inlet pipeline of the pre-washing methanol regeneration tower via a pre-washing methanol flash tank (i.e., separation device I).

[0055] The washing tower is equipped with a desulfurization section and a decarbonization section from bottom to top; the top outlet of the pre-washing tower is connected to the inlet pipeline of the desulfurization section of the washing tower; the outlets of the desulfurization section and the decarbonization section of the washing tower are respectively connected to the pipeline of the methanol-rich flash stripping system; the methanol-rich flash stripping system is connected to the pipeline of the tail gas washing tower.

[0056] The top outlet of the methanol-water separator is connected to the side wall inlet of the thermal regeneration tower; the side wall outlet is connected to the side wall inlet pipeline of the pre-washed methanol regeneration tower.

[0057] The bottom outlet of the pre-wash methanol regeneration tower is connected to the inlet of the side wall of the thermal regeneration tower. The pre-wash methanol regeneration tower is equipped with a reflux cooling device and has an outlet on the side wall for discharging acidic gases.

[0058] The top outlet of the thermal regeneration tower is connected to the pipeline of the methanol-rich flash stripping system via an acid gas separator (i.e., separation device II);

[0059] The pre-wash methanol flash tank is also equipped with a gas phase outlet to discharge the raw material gas after gas-liquid separation;

[0060] The scrubbing tower is equipped with a gas phase outlet to discharge purified gas;

[0061] The methanol-water flash evaporator is equipped with a gas phase outlet to discharge acidic gases;

[0062] The acid gas separator is equipped with a gas phase outlet to discharge the separated acid gas.

[0063] The specific implementation method is as follows: After cooling, the raw gas first separates condensate and sprays methanol in the water separation section of the pre-washing tower, and then proceeds to the pre-washing section of the pre-washing tower for pre-washing. The pre-washed rich methanol containing sulfides and impurities obtained in the pre-washing section of the pre-washing tower is subjected to medium-pressure flash evaporation in the pre-washed methanol flash tank to recover the effective gas. After being heated, it enters the pre-washed methanol regeneration tower. The amount of acidic gas containing impurities obtained at the top of the pre-washed methanol regeneration tower is relatively small, and it is directly combined with the acidic gas after cooling and reheating in the hot regeneration tower without cooling and sent for sulfur recovery. The lean methanol obtained at the bottom of the pre-washed methanol regeneration tower is sent to the lower section of the hot regeneration tower. In this process, no water enters the hot regeneration tower, so a water extraction and concentration section is not required; at the same time, the rich methanol separated from the acidic gas separator in the original hot regeneration tower is at a low temperature and free of impurities, and can be returned to the rich methanol flash evaporation and stripping system in the low-temperature zone.

[0064] The condensate separated from the water section of the pre-washing tower is heated and then the dissolved gas is separated in the methanol-water flash tank. The condensate enters the methanol-water separator, and the separated dissolved gas is mixed with acidic gas.

[0065] The beneficial effects that this application can produce include:

[0066] 1) The apparatus provided in this application includes a pre-wash methanol regeneration tower, where pre-wash methanol is regenerated separately, avoiding contamination of the entire methanol regeneration system by small amounts of impurity-rich methanol. In existing technologies, several tons of impurity-containing pre-wash methanol are mixed with hundreds of tons of main circulating methanol for regeneration, resulting in significant methanol loss in order to remove impurities. This apparatus removes impurities from the system with minimal methanol loss, preventing impurity accumulation and ensuring purification standards.

[0067] 2) The apparatus provided in this application integrates the pre-wash methanol regeneration tower reflux cooler system with the tower, resulting in a simple process that does not require a reflux pump; the number of devices is small, saving space.

[0068] 3) The apparatus provided in this application includes a pre-washing tower, which is divided into a feed gas water separation section and a pre-washing section. The feed gas is first separated into liquids and then pre-washed. The pre-washed methanol-rich gas is water-free and returns to the thermal regeneration tower after regeneration in the pre-washed methanol regeneration tower. The thermal regeneration tower eliminates the need for a water concentration section, resulting in a simpler structure. Furthermore, the methanol-water separated in the water separation section of the pre-washing tower is heat-exchanged and flash-evaporated before entering the methanol-water separation tower. The flash vapor is used for sulfur removal and recovery, reducing system impurities. The small return gas volume of the methanol-water separation tower also facilitates water separation in the system. This design ensures a low water content in the system.

[0069] 4) The apparatus provided in this application separates the pre-washing tower from the main washing tower, allowing for a smaller diameter of the pre-washing tower and a smaller height of the main washing tower, thus saving investment; it also avoids leakage from the collection pan that could cause the methanol-rich flow rate at the pre-washing section outlet to exceed the design value, and ensures stable load on the pre-washing methanol regeneration tower.

[0070] 5) The apparatus provided in this application has an optimized methanol-water separation tower design, which can ensure that more impurities are discharged from the system;

[0071] 6) The apparatus provided in this application has a backup nitrogen pipeline in the pre-wash methanol regeneration tower to assist gas stripping regeneration and improve the regeneration effect; when the impurity content in the raw gas is small, gas stripping can be used alone without thermal regeneration. Attached Figure Description

[0072] Figure 1 This is a diagram of the pre-wash methanol regeneration device in the embodiments of this application.

[0073] in:

[0074] T-001, Scrubbing tower; T-002, Thermal regeneration tower; T-003, Methanol-water separation tower;

[0075] T-004, Tail gas washing tower; T-005, Pre-wash methanol regeneration tower; T-006, Pre-wash tower;

[0076] P-001, Lean methanol pump; P-002, Thermal regeneration tower reflux pump; P-003, Methanol-water separator feed pump;

[0077] P-004, tail gas water washing tower bottom pump; P-005, pre-wash methanol regeneration tower bottom pump;

[0078] V-001, Pre-wash methanol flash tank; V-002, Acid gas separator; V-003, Thermal regeneration tower reflux tank; V-004, Methanol-water flash tank;

[0079] E-001, Raw material gas cooler; E-002, Reboiler for thermal regeneration tower; E-003, Reboiler for methanol-water separator tower;

[0080] E-004, Rich and Poor Methanol Heat Exchanger; E-005, Thermal Regeneration Tower Reflux Cooler; E-006, Pre-wash Methanol Heater;

[0081] E-007, Acid gas heat exchanger; E-008, Acid gas cooler; E-009, Wastewater heat exchanger;

[0082] E-010, Pre-washed methanol regeneration tower reboiler;

[0083] 1. Raw material gas; 2. Purified gas; 3. Carbon dioxide gas; 4. Tail gas; 5. Lean methanol; 6. Sulfur-free rich methanol; 7. Sulfur-containing rich methanol; 8. Pre-washed rich methanol; 9. Flash vapor; 10. Lean methanol; 11. Sulfur-containing rich methanol; 12. Methanol / water; 13. Methanol vapor; 14. Wastewater; 15. Acid gas; 16. Demineralized water. Detailed Implementation

[0084] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0085] Example 1

[0086] like Figure 1 As shown, a pre-wash methanol regeneration device includes a washing tower T-001, a thermal regeneration tower T-002, a methanol-water separation tower T-003, a tail gas washing tower T-004, a pre-wash methanol regeneration tower T-005, a pre-wash tower T-006, a lean methanol pump P-001, a thermal regeneration tower reflux pump P-002, a methanol-water separation tower feed pump P-003, a tail gas washing tower bottom pump P-004, a pre-wash methanol regeneration tower bottom pump P-005, a pre-wash methanol flash tank V-001, an acid gas separator V-002, and a thermal regeneration tower reflux tank V. -003, Methanol-Water Flash Tank V-004, Raw Material Gas Cooler E-001, Reboiler of Thermal Regeneration Tower E-002, Reboiler of Methanol-Water Separation Tower E-003, Lean-Rich Methanol Heat Exchanger E-004, Reflux Cooler of Thermal Regeneration Tower E-005, Pre-wash Methanol Heater E-006, Acid Gas Heat Exchanger E-007, Acid Gas Cooler E-008, Wastewater Heat Exchanger E-009, Reboiler of Pre-wash Methanol Regeneration Tower E-010; wherein the pre-wash methanol regeneration tower T-005 is equipped with a cooling reflux structure inside the top of the tower. The pre-wash methanol regeneration unit also includes a rich methanol flash stripping system, and the lean-rich methanol heat exchanger E-004 is located within the rich methanol flash stripping system.

[0087] The pre-washing tower T-006 has a water distribution section T-006A and a pre-washing section T-006B arranged sequentially from bottom to top. The outlet at the bottom of the pre-washing tower T-006 is connected to the side wall inlet of the methanol-water separator T-003 via a wastewater heat exchanger E-009 and a methanol-water flash tank V-004. The outlet of the pre-washing section T-006B of the pre-washing tower T-006 is connected to the side wall inlet of the distillation and regeneration section T-005A of the pre-washing methanol regeneration tower T-005 via a pre-washing methanol flash tank V-001 and a pre-washing methanol heater E-006. The water distribution section T-006A of the pre-washing tower T-006 has an inlet on its side wall, which is connected to the feed gas cooler E-001.

[0088] The scrubbing tower T-001 is equipped with a desulfurization section T-001A and a decarbonization section T-001B sequentially from bottom to top. The inlet of the desulfurization section T-001A is connected to the outlet at the top of the pre-washing tower T-006. The decarbonization section T-001B has multiple outlets on its sidewall, which are respectively connected to the rich methanol flash stripping system and the pre-washing section T-006B. The top of the scrubbing tower T-001 has an outlet connected to the feed gas cooler E-001. The inlet of the decarbonization section T-001B is connected to the lean and rich methanol heat exchanger E-004 in the rich methanol flash stripping system.

[0089] The methanol-rich flash stripping system is also connected to the feed gas cooler E-001.

[0090] The side wall outlet of the methanol-water separator T-003 is connected to the side wall inlet of the T-005A distillation regeneration section of the pre-washed methanol regeneration tower T-005; the top outlet of the methanol-water separator T-003 is connected to the side wall inlet of the regeneration tower T-002, and the bottom outlet is connected to the water heat exchanger E-009. A methanol-water separator reboiler E-003 is also provided at the bottom of the tower.

[0091] The bottom outlet of the pre-wash methanol regeneration tower T-005 is connected to the side wall inlet of the regeneration tower T-002 via the bottom pump P-005. The bottom of the tower is also equipped with a pre-wash methanol regeneration tower reboiler E-010. The side wall of the distillation regeneration section T-005A of the pre-wash methanol regeneration tower T-005 is also equipped with a low-pressure nitrogen inlet, and the side wall of the reflux cooling section T-005B is equipped with a discharge port for impurity-rich dirty methanol and an acid gas discharge port.

[0092] The thermal regeneration tower T-002 has an outlet I at its bottom, which is connected to the lean methanol and rich methanol heat exchanger E-004 in the rich methanol flash stripping system via a lean methanol pump P-001; it also has an outlet II, which is connected to the water heat exchanger E-009 via a methanol-water separator feed pump P-003; a thermal regeneration tower reboiler E-002 is also located at the bottom of the tower; the top outlet of the thermal regeneration tower T-002 is connected to a pre-wash methanol heater E-006, a thermal regeneration tower reflux cooler E-005, a thermal regeneration tower reflux tank V-003, an acid gas heat exchanger E-007, an acid gas cooler E-008, and an acid gas separator V-002; the bottom outlet of the acid gas separator V-002 is connected to the rich methanol flash stripping system, and the top outlet discharges acid gas; the bottom outlet of the thermal regeneration tower reflux tank V-003 is connected to the thermal regeneration tower T-002 via a thermal regeneration tower reflux pump P-002.

[0093] The methanol-water flash evaporator V-004 has an outlet at the top to discharge acidic gas;

[0094] The top outlet of the prewash methanol flash tank V-001 is connected to the lean methanol pump P-001;

[0095] The tail gas scrubbing tower T-004 is equipped with a demineralized water inlet and a tail gas outlet. The bottom outlet is connected to the wastewater heat exchanger E-009 via the tail gas scrubbing tower bottom pump P-004.

[0096] Example 2

[0097] The pre-wash methanol regeneration device prepared in Example 1 is used for pre-wash methanol regeneration, and the specific method is as follows:

[0098] The raw gas 1, containing water, ammonia, methanethiol, and ethanethiol, cooled by the raw gas cooler E-001, is first separated into intermediate condensate and raw gas I with a water content of 1-3 ppm in section T-006A of the pre-washing tower T-006. Then, the raw gas I with a water content of 1-3 ppm is further pre-washed in section T-006B of the pre-washing tower T-006. The pre-washed methanol 8, containing sulfides and impurities, obtained from section T-006B of the pre-washing tower T-006, is flashed under medium pressure in the pre-washed methanol flash tank V-001 to recover the effective gas. After being heated by the pre-washed methanol heater E-006, it enters the pre-washed methanol regeneration tower T-005. The acidic gas containing impurities obtained from the top of the pre-wash methanol regeneration tower T-005 is combined with the exhaust gas from the hot regeneration tower T-002. After being cooled and reheated by the pre-wash methanol heater E-006, the hot regeneration tower reflux cooler E-005, the hot regeneration tower reflux tank V-003, the acidic gas heat exchanger E-007, the acidic gas cooler E-008, and the acidic gas separator V-002, the combined gas is sent to sulfur recovery. The lean methanol obtained from the bottom of the pre-wash methanol regeneration tower T-005 is sent to the lower section of the hot regeneration tower T-002. In this process, the hot regeneration tower T-002 does not have a water extraction and concentration section. Simultaneously, the rich methanol separated by the acidic gas separator V-002 in the regeneration tower T-002 is at a lower temperature and free of impurities, and can be returned to the low-temperature rich methanol flash stripping system. The lean methanol 10 obtained from the bottom of the tower is then heat-exchanged by the wastewater heat exchanger E-009 and enters the methanol-water separator T-003 for distillation separation.

[0099] The sulfur-containing rich methanol 11 obtained from the rich methanol flash stripping system enters the regeneration tower T-002 for further regeneration. The resulting lean methanol 5 enters the washing tower T-001 section. The carbon dioxide gas 3 obtained from the rich methanol flash stripping system is discharged after heat exchange in the raw material gas cooler E-001, resulting in flash vapor 9 containing effective gases (including H2 and CO). This flash vapor 9 enters the raw material gas cooler E-001 via the lean methanol pump P-001. The methanol-containing tail gas obtained from the rich methanol flash stripping system is discharged after heat exchange in the raw material gas cooler E-001. After washing with demineralized water 16, the tail gas 4 is discharged.

[0100] The feed gas with a water and impurity content of less than 1 ppm, obtained from the top of section T-006B of pre-washing tower T-006, enters washing tower T-001. After desulfurization and decarbonization in desulfurization section T-001A and decarbonization section T-001B, sulfur-rich methanol 7 and sulfur-free rich methanol 6 are obtained, respectively, and then enter the rich methanol flash stripping system. The purified gas obtained from the top of washing tower T-001 is discharged after heat exchange in feed gas cooler E-001.

[0101] The methanol / water condensate 12 separated from the T-006A section of the pre-washing tower T-006 is heated and then separated into dissolved gas in the methanol-water flash tank V-004. The methanol / water condensate 12 enters the methanol-water separation tower T-003, and the separated dissolved gas is mixed with acid gas 15.

[0102] Methanol / water condensate 12 is distilled and separated in methanol-water separation tower T-003. The methanol vapor 13 obtained at the top of the tower is returned to the thermal regeneration tower T-002. The wastewater 14 at the bottom of methanol-water separation tower T-003 is discharged from the device. The methanol rich in impurities obtained in the middle of methanol-water separation tower T-003 enters the pre-wash methanol regeneration tower T-005 for regeneration.

[0103] This method effectively removes impurities that are prone to accumulate in the feed gas, ensuring the quality of lean methanol regeneration. The total sulfur content of the purified gas is less than 0.1 ppm, and the total sulfur content in the CO2 product gas and tail gas is less than 5 ppm. The system methanol loss is 10% of the original process, and the water content of the lean methanol in the system is less than 0.3%.

[0104] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A pre-wash methanol regeneration device, characterized in that, Includes a pre-washing tower, a washing tower, regeneration tower I, a methanol-water separation tower, a flash stripping system, and a regeneration tower II; The pre-washing tower, washing tower, flash stripping system, regeneration tower I, and methanol-water separator are connected in sequence by pipelines. The pre-washing tower is connected to the methanol-water separator by pipelines. The regeneration tower II is connected to the pre-washing tower, regeneration tower I, and methanol-water separator by pipelines. The pre-washing tower is provided with outlet I-1 at the bottom, outlet I-2 at the top, and outlet I-3 on the side wall; The washing tower has an inlet II-1 on its bottom sidewall, and the inlet II-1 is connected to the outlet I-2 pipeline; The regeneration tower I is equipped with an outlet III-1 at the bottom and inlets III-1 and III-2 on the side wall of the tower. The methanol-water separator is provided with inlet IV-1, inlet IV-2, outlet IV-1, and outlet IV-2. Inlet IV-1 is connected to outlet I-1 via pipeline, outlet III-1 is connected to inlet IV-2 via pipeline, and outlet IV-2 is connected to inlet III-1 via pipeline. The regeneration tower II has an inlet V-1, an inlet V-2, and an outlet V-1 on its side wall; the inlet V-1 is connected to the outlet I-3 pipeline, the inlet V-2 is connected to the outlet IV-1 pipeline, and the outlet V-1 is connected to the inlet III-2 pipeline. The regeneration tower II also has a gas phase outlet I.

2. The pre-wash methanol regeneration device according to claim 1, characterized in that, The pre-wash methanol regeneration unit also includes a tail gas water washing tower; The flash steam stripping system is connected to the tail gas washing tower pipeline.

3. The pre-wash methanol regeneration device according to claim 1, characterized in that, The pre-washing tower is equipped with a water distribution section and a pre-washing section sequentially from the bottom to the top of the tower. The outlet II-2 is located at the bottom of the pre-wash section.

4. The pre-wash methanol regeneration device according to claim 1, characterized in that, The washing tower is equipped with a desulfurization section and a decarbonization section from the bottom to the top of the tower. The desulfurization section and the decarbonization section are respectively connected to the flash steam stripping system pipeline; The decarbonization section is also connected to the pre-washing tower.

5. The pre-wash methanol regeneration device according to claim 1, characterized in that, The regeneration tower II is equipped with a reflux cooling device.

6. The pre-wash methanol regeneration device according to claim 1, characterized in that, The regeneration tower II is also equipped with a methanol discharge outlet; The regeneration tower II is also equipped with a nitrogen inlet II.

7. The pre-wash methanol regeneration device according to claim 1, characterized in that, The top of the regeneration tower I is equipped with outlet III-2; The outlet III-2 is connected to the flash steam stripping system via a pipeline; A separation device II is also provided on the pipeline connecting outlet III-2 to the flash steam stripping system; The separation device II is also provided with a gas phase outlet II; A separation device I is provided on the pipeline connecting the outlet I-3 and the inlet V-1; The separation device I is also provided with a gas phase outlet III; A separation device III is provided on the pipeline connecting the outlet I-1 and the inlet IV-1; The separation device III is also provided with a gas phase outlet IV.

8. A method for pre-washing methanol regeneration, characterized in that, A raw material gas containing water, ammonia, methanethiol, and ethanethiol is introduced into the pre-wash methanol regeneration device according to any one of claims 1 to 7 to achieve methanol regeneration.

9. The method of claim 8, wherein, The method includes the following steps: (1) The raw gas containing water, ammonia, methanethiol and ethanethiol is cooled and then enters the pre-washing tower. After water separation, condensate and raw gas I with a water content of 1 to 3 ppm are obtained. After the raw gas I with a water content of 1 to 3 ppm is pre-washed in the pre-washing section, raw gas II with an impurity content of less than 1 ppm and pre-washed methanol are obtained. The condensate includes water and methanol; Prewashing with methanol-rich materials includes methanol-rich materials, sulfur-containing compounds, and carbon-containing compounds; (2) The condensate enters a methanol-water separation tower, and after separation, gaseous methanol and water are obtained; The gaseous methanol enters the regeneration tower I, where it is regenerated to obtain acidic gaseous phase II and lean methanol; The pre-washed methanol-rich gas enters regeneration tower II for regeneration, yielding aqueous methanol I and acidic gas; The aqueous methanol I enters the regeneration tower I through inlet III-2, and is regenerated to obtain acidic gas phase II and lean methanol; The lean methanol enters the methanol-water separator via inlet IV-2 to separate gaseous methanol and water. (3) The raw material gas II enters the washing tower through inlet II-1 and is washed with lean methanol to obtain purified gas and rich methanol I. The rich methanol I enters the flash stripping system. The purified gas includes H2 and CO.

10. The method according to claim 9, characterized in that, In step (2), the condensate is separated by separation device III and then enters the methanol-water separation tower; The condensate is separated by separation device III to obtain acidic gas phase III; In step (2), the pre-washed rich methanol is separated by separation device I and then enters the regeneration tower II; The pre-washed methanol-rich gas is separated by separation device I to obtain flash vapor containing effective gases, which is then compressed and recovered. The effective gases include H2 and CO. In step (2), the acidic gas phase II is separated by separation device II to obtain acidic gas phase IV and methanol-rich II; The methanol-rich II enters the flash stripping system.