Anhydrous low-temperature methanol washing device and production method

Abstract

The invention belongs to an anhydrous low-temperature methanol washing device and a production method, comprising a raw gas pipeline and a methanol washing tower, wherein the raw gas pipeline is connected to the raw gas inlet of the methanol washing tower through a raw gas dehydration unit, and the top of the methanol washing tower is connected to a purified gas pipeline network; the liquid phase outlet at the bottom of the methanol washing tower is connected to the lean methanol spray pipeline inlet at the upper middle part of the methanol washing tower through a rich methanol processing unit; the device has the characteristics of simple structure, reasonable design, complete removal of moisture in the raw gas through the raw gas dehydration unit, and spraying through lean methanol liquid in the methanol washing tower, achieving the characteristics of less than 0.01% of water content in lean methanol / rich methanol / circulating methanol, thereby avoiding corrosion of related equipment, saving the purchase cost of the raw gas methanol spray device and the methanol-water separation tower, and omitting the separation of methanol and water in subsequent processes.

Description

Technical Field

[0001] The invention belongs to the technical field of gas purification, and specifically relates to an anhydrous low-temperature methanol washing device and a production method for removing impurity gases such as carbon dioxide and hydrogen sulfide from process gas by low-temperature methanol washing. Background Art

[0002] Low-temperature methanol washing technology is widely used in the removal of acidic gases such as carbon dioxide and hydrogen sulfide in the gas industry due to its technical advantages. In the low-temperature methanol washing process, low-temperature methanol absorbs acidic gases such as carbon dioxide and hydrogen sulfide to become methanol-rich liquid, which is very acidic; especially when the methanol-rich liquid contains water, its acidity and corrosiveness increase, causing corrosion of equipment internals and inner walls. In severe cases, it may cause defects such as tower plates falling off and methanol-rich filters being blocked, which is not conducive to the safe and stable operation of production. The conventional low-temperature methanol washing process absorbs moisture in the raw gas by spraying methanol and obtains aqueous methanol. The aqueous methanol is distilled in the methanol-water separation tower, methanol vapor is obtained at the top of the tower, and methanol-containing wastewater is obtained at the bottom of the tower. Methanol and water are extremely difficult to separate completely. Methanol vapor brings water into the circulating methanol, resulting in 0.1-0.5% moisture in the lean methanol at the top of the methanol washing tower, which ultimately leads to the strengthening of the acidity and corrosiveness of the rich methanol. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects in the prior art and to provide a water-free low-temperature methanol washing device and a production method which are simple in structure, reasonably designed, and can completely remove moisture from the raw gas through a raw gas dehydration unit and spray lean methanol liquid in a methanol washing tower, thereby achieving a water content of less than 0.01% in lean methanol / rich methanol / circulating methanol.

[0004] The object of the present invention is achieved in that:

[0005] A waterless low-temperature methanol washing device comprises a raw gas pipeline and a methanol washing tower, wherein the raw gas pipeline is connected to the raw gas inlet of the methanol washing tower through a raw gas dehydration unit, and the top of the methanol washing tower is connected to a purified gas pipeline network; the liquid phase outlet at the bottom of the methanol washing tower is connected to the inlet of a lean methanol spray pipeline in the upper middle part of the methanol washing tower through a rich methanol processing unit.

[0006] Preferably, the raw gas dehydration unit includes at least one dehydration section; when there are multiple dehydration sections, the multiple dehydration sections are connected in series.

[0007] Preferably, the dehydration section comprises a precooler and a water separation tank connected to the precooler, and a condensate recovery tank is provided at the bottom of the water separation tank.

[0008] Preferably, the dehydration section comprises at least one regenerated molecular sieve assembly, and when there are multiple regenerated molecular sieve assemblies, the multiple regenerated molecular sieve assemblies are connected in parallel.

[0009] Preferably, the regenerated molecular sieve assembly includes a bottom portion of the regenerated molecular sieve connected to the raw gas pipeline via a first tee and a first valve, a top portion of the regenerated molecular sieve connected to the gas outlet pipeline via a second tee and a second valve, the first tee connected to the molecular sieve regeneration gas outlet system via a third valve, and the second tee connected to the molecular sieve regeneration gas storage tank via a fourth valve.

[0010] Preferably, the raw gas dehydration unit includes a precooler connected to the raw gas pipeline, the outlet of the precooler is connected to the regenerated molecular sieve through a water separation tank, a first valve, and a first tee, and the outlet of the regenerated molecular sieve is connected to the raw gas inlet of the methanol washing tower through a second tee, a second valve, and the shell side of the raw gas cooler; there are two regenerated molecular sieve components.

[0011] Preferably, the rich methanol processing unit comprises a medium-pressure flash tower connected to the liquid phase outlet at the bottom of the methanol washing tower, the liquid phase outlet at the bottom of the medium-pressure flash tower is connected to the methanol decomposition tower, the liquid phase outlet at the bottom of the methanol decomposition tower is connected to the methanol regeneration tower through the methanol cooler pipe side and the methanol pump, and the liquid phase outlet at the bottom of the methanol regeneration tower is connected to the inlet of the lean methanol spray pipeline through the lean methanol cooler, the lean methanol tank, the lean methanol pump and the methanol cooler shell side.

[0012] Preferably, the gas phase outlet at the top of the medium-pressure flash tower is connected to the shell side inlet of the raw gas cooler through a circulating gas compressor; the gas phase outlet at the top of the methanol desorption tower is connected to the desorption gas pipeline network through the raw gas cooler pipe side; the top gas phase outlet of the methanol regeneration tower is connected to the acid gas treatment device.

[0013] A production method of an anhydrous low-temperature methanol washing device comprises the following steps:

[0014] Step 1: The raw gas in the raw gas pipeline is cooled by the precooler and then enters the water separation tank for gas-liquid separation, and the liquid phase after gas-liquid separation enters the condensate recovery device; the temperature of the raw gas is: 30-40°C, the pressure is: 4.0-6.5MPa, and the molar fraction of water is 0.1%-0.2%; the temperature of the raw gas at the outlet of the precooler 2 is: 5-10°C, and the cold source of the precooler is lithium bromide or ammonia cooling;

[0015] Step 2: the raw gas after gas-liquid separation enters the regenerated molecular sieve through the first valve for re-dehydration, and the dehydrated raw gas enters the shell side of the raw gas cooler through the second three-way and the second valve; the water content of the raw gas when passing through the outlet of the regenerated molecular sieve is less than 1ppm;

[0016] Step 3: The raw gas passing through the shell side of the raw gas cooler is cooled and enters the methanol scrubber, and the lean methanol entering from the lean methanol spray pipe inlet is sprayed, and the gas phase after spraying enters the purified gas pipe network, and the methanol-rich liquid at the bottom of the methanol scrubber enters the medium-pressure flash tower through the liquid phase outlet at the bottom of the methanol scrubber; the raw gas temperature at the shell side outlet of the raw gas cooler is: -10--20°C;

[0017] Step 4: The methanol-rich liquid solution enters the medium-pressure flash tower for medium-pressure flash evaporation, and the steam after the medium-pressure flash evaporation is pressurized by the circulating gas compressor and then returned to the shell side of the raw gas cooler to repeat the above step 3; the liquid phase after the medium-pressure flash evaporation enters the methanol analysis tower; the flash evaporation pressure of the medium-pressure flash tower is: 1.2-1.7MPa; the above-mentioned circulating gas compressor is a multi-stage centrifugal compressor with an interstage circulating water cooler, and the flash gas temperature at the outlet of the circulating gas compressor is 20-40°C;

[0018] Step 5: The liquid phase after medium-pressure flash evaporation enters the methanol analysis tower for analysis, and the gas phase enters the raw gas cooler tube side through the gas phase outlet at the top of the methanol analysis tower, exchanges heat with the raw gas in its shell side, and then enters the analysis gas pipeline network; the bottom pressure of the methanol analysis tower is 0.05-0.3MPa; the analysis gas temperature passing through the raw gas cooler tube side is 10-20°C;

[0019] Step 6: The liquid phase at the bottom of the methanol analysis tower is heated through the methanol cooler pipe and pressurized by the methanol pump and then sent to the methanol regeneration tower; the gas phase in the methanol regeneration tower enters the acid gas treatment device through the top gas phase outlet of the methanol regeneration tower for acid gas treatment; the lean methanol liquid in the methanol regeneration tower is sent to the lean methanol tank through the lean methanol cooler; the lean methanol cooler adopts a circulating water cooling method;

[0020] Step 7: The lean methanol liquid in the lean methanol tank is pressurized by a lean methanol pump and cooled in the shell side of a methanol cooler, and then sent to a methanol washing tower through the inlet of a lean methanol spray pipe for spraying; the pressure of the lean methanol liquid at the outlet of the lean methanol pump is 5.0-7.5MPa; the temperature of the lean methanol liquid at the shell side outlet of the methanol cooler is -55°C to -62°C.

[0021] Preferably, in step 2, there are two regenerated molecular sieves, which are in a state of mutual reserve;

[0022] When the first regenerated molecular sieve is in an adsorption state, the second regenerated molecular sieve is in a regeneration state;

[0023] When the second regenerated molecular sieve is in the adsorption state, the first regenerated molecular sieve is in the regeneration state;

[0024] When the regenerated molecular sieve is in the adsorption state, the first valve and the second valve are in the open state, and the third valve and the fourth valve are in the closed state; the raw gas enters the regenerated molecular sieve through the first valve for adsorption, and the adsorbed raw gas is discharged from the regenerated molecular sieve through the second valve;

[0025] When the regenerated molecular sieve is in the regeneration state, the third valve and the fourth valve are in the open state, and the first valve and the second valve are in the closed state; the nitrogen in the molecular sieve regeneration gas storage tank enters the regenerated molecular sieve through the fourth valve for regeneration, and the regenerated nitrogen enters the molecular sieve regeneration outlet system through the third valve.

[0026] According to the above scheme, an anhydrous low-temperature methanol washing device and a production method are made. The present invention sets a raw gas dehydration unit to remove water from the raw gas, and sprays lean methanol liquid in the methanol washing tower to make the water content of lean methanol / rich methanol / circulating methanol in the whole system less than 0.01%. The above device can not only avoid corrosion of related equipment, but also save the cost investment of the raw gas methanol spraying device and the methanol-water separation tower, and eliminates the separation of methanol and water in the subsequent process, effectively saving the operating cost; further, the present invention effectively separates the water in the raw gas through a combination of cooling separation and regeneration molecular sieve components, thereby avoiding water from entering the subsequent system; it has the advantages of simple structure, reasonable design, simple process, easy operation and inherent safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the regenerated molecular sieve component in the present invention.

[0029] In the figure above: 1. Raw gas pipeline; 2. Precooler; 3. Water separation tank; 4. Condensate recovery tank; 5. First valve; 6. First tee; 7. Regeneration molecular sieve; 8. Third valve; 9. Second valve; 10. Second tee; 11. Raw gas cooler; 12. Methanol washing tower; 13. Purification gas pipeline network; 14. Medium-pressure flash tower; 15. Methanol analysis tower; 16. Methanol cooler; 17. Methanol pump; 18. Methanol regeneration tower; 19. Acid gas treatment device; 20. Lean methanol cooler; 21. Lean methanol tank; 22. Lean methanol pump; 23. Circulating gas compressor; 24. Analysis gas pipeline network; 25. Molecular sieve regeneration gas storage tank; 26. Fourth valve; 27. Lean methanol spray pipeline inlet; 28. Molecular sieve regeneration outlet system. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation of the present invention is now described with reference to the accompanying drawings, in which the same reference numerals represent the same components. In order to make the drawings concise, each figure only schematically shows the parts related to the invention, and they do not represent the actual structure of the product.

[0031] like Figure 1 , 2 As shown, the present invention is an anhydrous low-temperature methanol washing device and a production method, wherein the anhydrous low-temperature methanol washing device includes a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to the purified gas pipeline network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the lean methanol spray pipeline inlet 27 in the upper and middle part of the methanol washing tower 12 through a rich methanol processing unit.

[0032] Furthermore, the raw gas dehydration unit includes at least one dehydration section; when there are multiple dehydration sections, the multiple dehydration sections are connected in series.

[0033] Furthermore, the dehydration section includes a precooler 2 and a water separation tank 3 connected to the precooler 2 , and a condensate recovery tank 4 is provided at the bottom of the water separation tank 3 .

[0034] Furthermore, the dehydration section includes at least one regenerated molecular sieve assembly, and when there are multiple regenerated molecular sieve assemblies, the multiple regenerated molecular sieve assemblies are connected in parallel.

[0035] Furthermore, the regenerated molecular sieve assembly includes a regenerated molecular sieve 7 whose bottom is connected to the raw gas pipeline through a first tee 6 and a first valve 5, the top of the regenerated molecular sieve 7 is connected to the gas outlet pipeline through a second tee 10 and a second valve 9, the first tee 6 is connected to the molecular sieve regeneration gas outlet system 28 through a third valve 8, and the second tee 10 is connected to the molecular sieve regeneration gas storage tank 25 through a fourth valve 26.

[0036] Furthermore, the raw gas dehydration unit includes a precooler 2 connected to the raw gas pipeline 1, the outlet of the precooler 2 is connected to the regenerated molecular sieve 7 through the water separation tank 3, the first valve 5, and the first tee 6, and the outlet of the regenerated molecular sieve 7 is connected to the raw gas inlet of the methanol washing tower 12 through the second tee 10, the second valve 9 and the shell side of the raw gas cooler 11; there are two regenerated molecular sieve components.

[0037] Furthermore, the rich methanol processing unit includes a medium-pressure flash tower 14 connected to the liquid phase outlet at the bottom of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol decomposition tower 15, the liquid phase outlet at the bottom of the methanol decomposition tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the methanol cooler 16 shell side.

[0038] Furthermore, the gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol desorption tower 15 is connected to the desorption gas pipeline network 24 through the pipe side of the raw gas cooler 11; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0039] A production method of an anhydrous low-temperature methanol washing device comprises the following steps:

[0040] Step 1: The raw gas in the raw gas pipeline 1 is cooled by the precooler 2 and then enters the water separation tank 3 for gas-liquid separation, and the liquid phase after gas-liquid separation enters the condensate recovery device 4; the temperature of the raw gas is: 30-40°C, the pressure is: 4.0-6.5MPa, and the molar fraction of water is 0.1%-0.2%; the temperature of the raw gas at the outlet of the precooler 2 is: 5-10°C, and the cold source of the precooler 2 is lithium bromide or ammonia cooling;

[0041] Step 2: The raw gas after gas-liquid separation enters the regenerated molecular sieve 7 through the first valve 5 for re-dehydration, and the dehydrated raw gas enters the shell side of the raw gas cooler 11 through the second three-way 10 and the second valve 9; the water content of the raw gas at the outlet of the regenerated molecular sieve 7 is less than 1ppm;

[0042] Step 3: The raw gas passing through the shell side of the raw gas cooler 11 is cooled and then enters the methanol washing tower 12, and the lean methanol entering from the lean methanol spray pipe inlet 27 is sprayed, and the gas phase after spraying enters the purified gas pipe network 13, and the methanol-rich liquid at the bottom of the methanol washing tower 12 enters the medium-pressure flash tower 14 through the liquid phase outlet at the bottom of the methanol washing tower 12; the raw gas temperature at the shell side outlet of the raw gas cooler 11 is: -10--20°C;

[0043] Step 4: The methanol-rich liquid solution enters the medium-pressure flash tower 14 for medium-pressure flash evaporation. The steam after the medium-pressure flash evaporation is pressurized by the circulating gas compressor 23 and then returns to the shell side of the raw gas cooler 11 to repeat the above step 3; the liquid phase after the medium-pressure flash evaporation enters the methanol desorption tower 15; the flash evaporation pressure of the medium-pressure flash tower 14 is: 1.2-1.7MPa; the above-mentioned circulating gas compressor 23 is a multi-stage centrifugal compressor with an interstage circulating water cooler, and the flash gas temperature at the outlet of the circulating gas compressor 23 is 20-40°C;

[0044] Step 5: The liquid phase after the medium-pressure flash evaporation enters the methanol analysis tower 15 for analysis, and the gas phase enters the raw gas cooler 11 tube side through the gas phase outlet at the top of the methanol analysis tower 15, exchanges heat with the raw gas in its shell side, and then enters the analysis gas pipeline network 24; the bottom pressure of the methanol analysis tower 15 is 0.05-0.3MPa; the analysis gas temperature passing through the raw gas cooler 11 tube side is 10-20°C;

[0045] Step 6: The liquid phase at the bottom of the methanol analysis tower 15 is heated through the methanol cooler 16 pipe and pressurized by the methanol pump 17 and then sent to the methanol regeneration tower 18; the gas phase in the methanol regeneration tower 18 enters the acid gas treatment device 19 through the top gas phase outlet of the methanol regeneration tower 18 for acid gas treatment; the lean methanol liquid in the methanol regeneration tower 18 is sent to the lean methanol tank 21 through the lean methanol cooler 20; the lean methanol cooler 20 adopts a circulating water cooling method;

[0046] Step 7: The lean methanol liquid in the lean methanol tank 21 is pressurized by the lean methanol pump 22 and cooled in the shell side of the methanol cooler 16, and then sent to the methanol washing tower 12 through the lean methanol spray pipe inlet 27 for spraying; the pressure of the lean methanol liquid at the outlet of the lean methanol pump 22 is: 5.0-7.5MPa; the temperature of the lean methanol liquid at the shell side outlet of the methanol cooler 16 is: -55°C to -62°C.

[0047] Furthermore, in step 2, there are two regenerated molecular sieves 7, which are in a state of mutual backup;

[0048] When the first regenerated molecular sieve 7 is in an adsorption state, the second regenerated molecular sieve 7 is in a regeneration state;

[0049] When the second regenerated molecular sieve 7 is in the adsorption state, the first regenerated molecular sieve 7 is in the regeneration state;

[0050] When the regenerated molecular sieve 7 is in the adsorption state, the first valve 5 and the second valve 9 are in the open state, and the third valve 8 and the fourth valve 26 are in the closed state; the raw gas enters the regenerated molecular sieve 7 through the first valve 5 for adsorption, and the adsorbed raw gas is discharged from the regenerated molecular sieve 7 through the second valve 9;

[0051] When the regenerated molecular sieve 7 is in the regeneration state, the third valve 8 and the fourth valve 26 are in the open state, and the first valve 5 and the second valve 9 are in the closed state; the nitrogen in the molecular sieve regeneration gas storage tank 25 enters the regenerated molecular sieve 7 through the fourth valve 26 for regeneration, and the regenerated nitrogen enters the molecular sieve regeneration outlet system 28 through the third valve 8.

[0052] In order to explain the present invention in more detail, the present invention is further described in conjunction with embodiments. The specific embodiments are as follows:

[0053] Example 1

[0054] A water-free low-temperature methanol washing device comprises a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to a purified gas pipe network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the lean methanol spray pipeline inlet 27 at the upper middle part of the methanol washing tower 12 through a rich methanol treatment unit. The raw gas dehydration unit comprises a dehydration part; the dehydration part comprises a precooler 2 and a water separation tank 3 connected to the precooler 2, and a condensate recovery tank 4 is provided at the bottom of the water separation tank 3. The rich methanol processing unit includes a medium-pressure flash tower 14 connected to the liquid phase outlet at the bottom of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol decomposition tower 15, the liquid phase outlet at the bottom of the methanol decomposition tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the shell side of the methanol cooler 16. The gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol decomposition tower 15 is connected to the decomposition gas pipeline network 24 through the raw gas cooler 11 pipe side; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0055] Example 2

[0056] A water-free low-temperature methanol washing device comprises a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to a purified gas pipe network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the lean methanol spray pipeline inlet 27 at the upper middle part of the methanol washing tower 12 through a rich methanol treatment unit. The raw gas dehydration unit comprises two dehydration parts; the two dehydration parts are connected in series; both dehydration parts are in the form of cooling dehydration, that is, the dehydration part comprises a precooler 2 and a water separation tank 3 connected to the precooler 2, and a condensate recovery tank 4 is provided at the bottom of the water separation tank 3. The rich methanol processing unit includes a medium-pressure flash tower 14 connected to the liquid phase outlet at the bottom of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol decomposition tower 15, the liquid phase outlet at the bottom of the methanol decomposition tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the shell side of the methanol cooler 16. The gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol decomposition tower 15 is connected to the decomposition gas pipeline network 24 through the raw gas cooler 11 pipe side; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0057] Example 3

[0058] A water-free low-temperature methanol washing device comprises a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to a purified gas pipe network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the lean methanol spray pipeline inlet 27 at the upper middle part of the methanol washing tower 12 through a rich methanol treatment unit. The raw gas dehydration unit is a dehydration section; the dehydration section comprises a regenerated molecular sieve assembly. The regenerated molecular sieve assembly comprises a regenerated molecular sieve 7, the bottom of which is connected to the raw gas pipeline through a first tee 6 and a first valve 5, the top of the regenerated molecular sieve 7 is connected to the gas outlet pipeline through a second tee 10 and a second valve 9, the first tee 6 is connected to the molecular sieve regeneration gas outlet system 28 through a third valve 8, and the second tee 10 is connected to the molecular sieve regeneration gas storage tank 25 through a fourth valve 26. The raw gas dehydration unit includes a precooler 2 connected to the raw gas pipeline 1, the outlet of the precooler 2 is connected to the regenerated molecular sieve 7 through the water separation tank 3, the first valve 5, and the first tee 6, and the outlet of the regenerated molecular sieve 7 is connected to the raw gas inlet of the methanol washing tower 12 through the second tee 10, the second valve 9 and the shell side of the raw gas cooler 11. The rich methanol processing unit includes a medium-pressure flash tower 14 connected to the liquid phase outlet at the bottom of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol analysis tower 15, the liquid phase outlet at the bottom of the methanol analysis tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the shell side of the methanol cooler 16. The gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol desorption tower 15 is connected to the desorption gas pipeline network 24 through the pipe side of the raw gas cooler 11; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0059] Example 4

[0060] A water-free low-temperature methanol washing device comprises a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to a purified gas pipe network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the inlet 27 of the lean methanol spray pipeline in the middle and upper part of the methanol washing tower 12 through a rich methanol treatment unit. The raw gas dehydration unit comprises two dehydration parts; both dehydration parts are in the form of regenerated molecular sieve dehydration and are connected in series. The dehydration part comprises two regenerated molecular sieve assemblies, and the two regenerated molecular sieve assemblies are connected in parallel. The regenerated molecular sieve assembly comprises a regenerated molecular sieve 7, the bottom of which is connected to the raw gas pipeline through a first tee 6 and a first valve 5, the top of the regenerated molecular sieve 7 is connected to the gas outlet pipeline through a second tee 10 and a second valve 9, the first tee 6 is connected to the molecular sieve regeneration gas outlet system 28 through a third valve 8, and the second tee 10 is connected to the molecular sieve regeneration gas storage tank 25 through a fourth valve 26. The raw gas dehydration unit includes a precooler 2 connected to the raw gas pipeline 1, the outlet of the precooler 2 is connected to the regenerated molecular sieve 7 through the water separation tank 3, the first valve 5, and the first tee 6, and the outlet of the regenerated molecular sieve 7 is connected to the raw gas inlet of the methanol washing tower 12 through the second tee 10, the second valve 9 and the shell side of the raw gas cooler 11; there are two regenerated molecular sieve components. The rich methanol processing unit includes a medium-pressure flash tower 14 connected to the bottom liquid phase outlet of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol analysis tower 15, the liquid phase outlet at the bottom of the methanol analysis tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the shell side of the methanol cooler 16. The gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol desorption tower 15 is connected to the desorption gas pipeline network 24 through the pipe side of the raw gas cooler 11; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0061] Example 5

[0062] A waterless low-temperature methanol washing device comprises a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to a purified gas pipe network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the lean methanol spray pipeline inlet 27 at the upper middle part of the methanol washing tower 12 through a rich methanol treatment unit. The raw gas dehydration unit is composed of two dehydration sections; the two dehydration sections are connected in series, the front dehydration section is in the form of cooling dehydration, and the rear dehydration section is in the form of regeneration molecular sieve dehydration. The front dehydration section comprises a precooler 2 and a water separation tank 3 connected to the precooler 2, and a condensate recovery tank 4 is provided at the bottom of the water separation tank 3. The post-dehydration section includes a regenerated molecular sieve assembly, wherein the bottom of the regenerated molecular sieve assembly includes a regenerated molecular sieve 7 connected to the raw gas pipeline through a first tee 6 and a first valve 5, the top of the regenerated molecular sieve 7 is connected to the gas outlet pipeline through a second tee 10 and a second valve 9, the first tee 6 is connected to the molecular sieve regeneration gas outlet system 28 through a third valve 8, and the second tee 10 is connected to the molecular sieve regeneration gas storage tank 25 through a fourth valve 26. The raw gas dehydration unit includes a precooler 2 connected to the raw gas pipeline 1, the outlet of the precooler 2 is connected to the regenerated molecular sieve 7 through a water separation tank 3, a first valve 5, and a first tee 6, and the outlet of the regenerated molecular sieve 7 is connected to the raw gas inlet of the methanol washing tower 12 through a second tee 10, a second valve 9 and the shell side of the raw gas cooler 11. The rich methanol processing unit includes a medium-pressure flash tower 14 connected to the liquid phase outlet at the bottom of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol decomposition tower 15, the liquid phase outlet at the bottom of the methanol decomposition tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the shell side of the methanol cooler 16. The gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol decomposition tower 15 is connected to the decomposition gas pipeline network 24 through the raw gas cooler 11 pipe side; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0063] Example 6

[0064] A water-free low-temperature methanol washing device comprises a raw gas pipeline 1 and a methanol washing tower 12, wherein the raw gas pipeline 1 is connected to the raw gas inlet of the methanol washing tower 12 through a raw gas dehydration unit, and the top of the methanol washing tower 12 is connected to a purified gas pipe network 13; the liquid phase outlet at the bottom of the methanol washing tower 12 is connected to the lean methanol spray pipeline inlet 27 at the upper middle part of the methanol washing tower 12 through a rich methanol treatment unit. The raw gas dehydration unit is composed of two dehydration sections; the two dehydration sections are connected in series, the front dehydration section is in the form of cooling dehydration, and the rear dehydration section is in the form of regeneration molecular sieve dehydration. The front dehydration section comprises a precooler 2 and a water separation tank 3 connected to the precooler 2, and a condensate recovery tank 4 is provided at the bottom of the water separation tank 3. The rear dehydration section comprises two regeneration molecular sieve assemblies, and the two regeneration molecular sieve assemblies are connected in parallel. The regenerated molecular sieve assembly includes a regenerated molecular sieve 7, the bottom of which is connected to the raw gas pipeline through a first tee 6 and a first valve 5, the top of which is connected to the gas outlet pipeline through a second tee 10 and a second valve 9, the first tee 6 is connected to the molecular sieve regeneration gas outlet system 28 through a third valve 8, and the second tee 10 is connected to the molecular sieve regeneration gas storage tank 25 through a fourth valve 26. The raw gas dehydration unit includes a precooler 2 connected to the raw gas pipeline 1, the outlet of the precooler 2 is connected to the regenerated molecular sieve 7 through a water separation tank 3, a first valve 5, and a first tee 6, and the outlet of the regenerated molecular sieve 7 is connected to the raw gas inlet of the methanol washing tower 12 through a second tee 10, a second valve 9 and the shell side of the raw gas cooler 11. The rich methanol processing unit includes a medium-pressure flash tower 14 connected to the liquid phase outlet at the bottom of the methanol washing tower 12, the liquid phase outlet at the bottom of the medium-pressure flash tower 14 is connected to the methanol decomposition tower 15, the liquid phase outlet at the bottom of the methanol decomposition tower 15 is connected to the methanol regeneration tower 18 through the methanol cooler 16 pipe side and the methanol pump 17, and the liquid phase outlet at the bottom of the methanol regeneration tower 18 is connected to the lean methanol spray pipeline inlet 27 through the lean methanol cooler 20, the lean methanol tank 21, the lean methanol pump 22 and the shell side of the methanol cooler 16. The gas phase outlet at the top of the medium-pressure flash tower 14 is connected to the shell side inlet of the raw gas cooler 11 through the circulating gas compressor 23; the gas phase outlet at the top of the methanol decomposition tower 15 is connected to the decomposition gas pipeline network 24 through the raw gas cooler 11 pipe side; the top gas phase outlet of the methanol regeneration tower 18 is connected to the acid gas treatment device 19.

[0065] Example 7

[0066] The production method of the anhydrous low-temperature methanol washing device is carried out in the structural form of the above embodiment 5, and includes the following steps:

[0067] Step 1: The raw gas in the raw gas pipeline 1 is cooled by the precooler 2 and then enters the water separation tank 3 for gas-liquid separation, and the liquid phase after gas-liquid separation enters the condensate recovery device 4; the temperature of the raw gas is: 30-40°C, the pressure is: 4.0-6.5MPa, and the molar fraction of water is 0.1%-0.2%; the temperature of the raw gas at the outlet of the precooler 2 is: 5-10°C, and the cold source of the precooler 2 is lithium bromide;

[0068] Step 2: The raw gas after gas-liquid separation enters the regenerated molecular sieve 7 through the first valve 5 for re-dehydration, and the dehydrated raw gas enters the shell side of the raw gas cooler 11 through the second three-way 10 and the second valve 9; the water content of the raw gas at the outlet of the regenerated molecular sieve 7 is 0.8ppm;

[0069] Step 3: The raw gas passing through the shell side of the raw gas cooler 11 is cooled and then enters the methanol washing tower 12, and the lean methanol entering from the lean methanol spray pipe inlet 27 is sprayed, and the gas phase after spraying enters the purified gas pipe network 13, and the methanol-rich liquid at the bottom of the methanol washing tower 12 enters the medium-pressure flash tower 14 through the liquid phase outlet at the bottom of the methanol washing tower 12; the raw gas temperature at the shell side outlet of the raw gas cooler 11 is: -10--20°C;

[0070] Step 4: The methanol-rich liquid solution enters the medium-pressure flash tower 14 for medium-pressure flash evaporation. The steam after the medium-pressure flash evaporation is pressurized by the circulating gas compressor 23 and then returns to the shell side of the raw gas cooler 11 to repeat the above step 3; the liquid phase after the medium-pressure flash evaporation enters the methanol desorption tower 15; the flash evaporation pressure of the medium-pressure flash tower 14 is: 1.2-1.7MPa; the above-mentioned circulating gas compressor 23 is a multi-stage centrifugal compressor with an interstage circulating water cooler, and the flash gas temperature at the outlet of the circulating gas compressor 23 is 20-40°C;

[0071] Step 5: The liquid phase after the medium-pressure flash evaporation enters the methanol analysis tower 15 for analysis, and the gas phase enters the raw gas cooler 11 tube side through the gas phase outlet at the top of the methanol analysis tower 15, exchanges heat with the raw gas in its shell side, and then enters the analysis gas pipeline network 24; the bottom pressure of the methanol analysis tower 15 is 0.05-0.3MPa; the analysis gas temperature passing through the raw gas cooler 11 tube side is 10-20°C;

[0072] Step 6: The liquid phase at the bottom of the methanol analysis tower 15 is heated through the methanol cooler 16 pipe and pressurized by the methanol pump 17 and then sent to the methanol regeneration tower 18; the gas phase in the methanol regeneration tower 18 enters the acid gas treatment device 19 through the top gas phase outlet of the methanol regeneration tower 18 for acid gas treatment; the lean methanol liquid in the methanol regeneration tower 18 is sent to the lean methanol tank 21 through the lean methanol cooler 20; the lean methanol cooler 20 adopts a circulating water cooling method;

[0073] Step 7: The lean methanol liquid in the lean methanol tank 21 is pressurized by the lean methanol pump 22 and cooled in the shell side of the methanol cooler 16, and then sent to the methanol washing tower 12 through the lean methanol spray pipe inlet 27 for spraying; the pressure of the lean methanol liquid at the outlet of the lean methanol pump 22 is: 5.0-7.5MPa; the temperature of the lean methanol liquid at the shell side outlet of the methanol cooler 16 is: -55°C to -62°C.

[0074] Example 8

[0075] The production method of the anhydrous low-temperature methanol washing device is carried out in the structural form of the above-mentioned embodiment 6, and includes the following steps:

[0076] Step 1: The raw gas in the raw gas pipeline 1 is cooled by the precooler 2 and then enters the water separation tank 3 for gas-liquid separation, and the liquid phase after gas-liquid separation enters the condensate recovery device 4; the temperature of the raw gas is: 30-40°C, the pressure is: 4.0-6.5MPa, and the molar fraction of water is 0.1%-0.2%; the temperature of the raw gas at the outlet of the precooler 2 is: 5-10°C, and the cold source of the precooler 2 is ammonia cooling;

[0077] Step 2: The raw gas after gas-liquid separation enters the regenerated molecular sieve 7 through the first valve 5 for re-dehydration, and the dehydrated raw gas enters the shell side of the raw gas cooler 11 through the second three-way 10 and the second valve 9; the water content of the raw gas at the outlet of the regenerated molecular sieve 7 is 0.6ppm;

[0078] Step 3: The raw gas passing through the shell side of the raw gas cooler 11 is cooled and then enters the methanol washing tower 12, and the lean methanol entering from the lean methanol spray pipe inlet 27 is sprayed, and the gas phase after spraying enters the purified gas pipe network 13, and the methanol-rich liquid at the bottom of the methanol washing tower 12 enters the medium-pressure flash tower 14 through the liquid phase outlet at the bottom of the methanol washing tower 12; the raw gas temperature at the shell side outlet of the raw gas cooler 11 is: -10--20°C;

[0079] Step 4: The methanol-rich liquid solution enters the medium-pressure flash tower 14 for medium-pressure flash evaporation. The steam after the medium-pressure flash evaporation is pressurized by the circulating gas compressor 23 and then returns to the shell side of the raw gas cooler 11 to repeat the above step 3; the liquid phase after the medium-pressure flash evaporation enters the methanol desorption tower 15; the flash evaporation pressure of the medium-pressure flash tower 14 is: 1.2-1.7MPa; the above-mentioned circulating gas compressor 23 is a multi-stage centrifugal compressor with an interstage circulating water cooler, and the flash gas temperature at the outlet of the circulating gas compressor 23 is 20-40°C;

[0080] Step 5: The liquid phase after the medium-pressure flash evaporation enters the methanol analysis tower 15 for analysis, and the gas phase enters the raw gas cooler 11 tube side through the gas phase outlet at the top of the methanol analysis tower 15, exchanges heat with the raw gas in its shell side, and then enters the analysis gas pipeline network 24; the bottom pressure of the methanol analysis tower 15 is 0.05-0.3MPa; the analysis gas temperature passing through the raw gas cooler 11 tube side is 10-20°C;

[0081] Step 6: The liquid phase at the bottom of the methanol analysis tower 15 is heated through the methanol cooler 16 pipe and pressurized by the methanol pump 17 and then sent to the methanol regeneration tower 18; the gas phase in the methanol regeneration tower 18 enters the acid gas treatment device 19 through the top gas phase outlet of the methanol regeneration tower 18 for acid gas treatment; the lean methanol liquid in the methanol regeneration tower 18 is sent to the lean methanol tank 21 through the lean methanol cooler 20; the lean methanol cooler 20 adopts a circulating water cooling method;

[0082] Step 7: The lean methanol liquid in the lean methanol tank 21 is pressurized by the lean methanol pump 22 and cooled in the shell side of the methanol cooler 16, and then sent to the methanol washing tower 12 through the lean methanol spray pipe inlet 27 for spraying; the lean methanol liquid pressure at the outlet of the lean methanol pump 22 is: 5.0-7.5MPa; the lean methanol liquid temperature at the shell side outlet of the methanol cooler 16 is: -55--62℃.

[0083] Furthermore, in step 2, there are two regenerated molecular sieves 7, which are in a state of mutual backup;

[0084] When the first regenerated molecular sieve 7 is in an adsorption state, the second regenerated molecular sieve 7 is in a regeneration state;

[0085] When the second regenerated molecular sieve 7 is in the adsorption state, the first regenerated molecular sieve 7 is in the regeneration state;

[0086] When the regenerated molecular sieve 7 is in the adsorption state, the first valve 5 and the second valve 9 are in the open state, and the third valve 8 and the fourth valve 26 are in the closed state; the raw gas enters the regenerated molecular sieve 7 through the first valve 5 for adsorption, and the adsorbed raw gas is discharged from the regenerated molecular sieve 7 through the second valve 9;

[0087] When the regenerated molecular sieve 7 is in the regeneration state, the third valve 8 and the fourth valve 26 are in the open state, and the first valve 5 and the second valve 9 are in the closed state; the nitrogen in the molecular sieve regeneration gas storage tank 25 enters the regenerated molecular sieve 7 through the fourth valve 26 for regeneration, and the regenerated nitrogen enters the molecular sieve regeneration outlet system 28 through the third valve 8.

[0088] Example 9

[0089] The production method of the anhydrous low-temperature methanol washing device is carried out in the structural form of the above-mentioned embodiment 6, and includes the following steps:

[0090] Step 1: The raw gas in the raw gas pipeline 1 is cooled by the precooler 2 and then enters the water separation tank 3 for gas-liquid separation, and the liquid phase after gas-liquid separation enters the condensate recovery device 4; the temperature of the raw gas is: 30-40°C, the pressure is: 4.0-6.5MPa, and the molar fraction of water is 0.1%-0.2%; the temperature of the raw gas at the outlet of the precooler 2 is: 5-10°C, and the cold source of the precooler 2 is lithium bromide;

[0091] Step 2: The raw gas after gas-liquid separation enters the regenerated molecular sieve 7 through the first valve 5 for re-dehydration, and the dehydrated raw gas enters the shell side of the raw gas cooler 11 through the second three-way 10 and the second valve 9; the water content of the raw gas at the outlet of the regenerated molecular sieve 7 is 0.7ppm;

[0092] Step 3: The raw gas passing through the shell side of the raw gas cooler 11 is cooled and then enters the methanol washing tower 12, and the lean methanol entering from the lean methanol spray pipe inlet 27 is sprayed, and the gas phase after spraying enters the purified gas pipe network 13, and the methanol-rich liquid at the bottom of the methanol washing tower 12 enters the medium-pressure flash tower 14 through the liquid phase outlet at the bottom of the methanol washing tower 12; the raw gas temperature at the shell side outlet of the raw gas cooler 11 is: -10--20°C;

[0093] Step 4: The methanol-rich liquid solution enters the medium-pressure flash tower 14 for medium-pressure flash evaporation. The steam after the medium-pressure flash evaporation is pressurized by the circulating gas compressor 23 and then returns to the shell side of the raw gas cooler 11 to repeat the above step 3; the liquid phase after the medium-pressure flash evaporation enters the methanol desorption tower 15; the flash evaporation pressure of the medium-pressure flash tower 14 is: 1.2-1.7MPa; the above-mentioned circulating gas compressor 23 is a multi-stage centrifugal compressor with an interstage circulating water cooler, and the flash gas temperature at the outlet of the circulating gas compressor 23 is 20-40°C;

[0094] Step 5: The liquid phase after the medium-pressure flash evaporation enters the methanol analysis tower 15 for analysis, and the gas phase enters the raw gas cooler 11 tube side through the gas phase outlet at the top of the methanol analysis tower 15, exchanges heat with the raw gas in its shell side, and then enters the analysis gas pipeline network 24; the bottom pressure of the methanol analysis tower 15 is 0.05-0.3MPa; the analysis gas temperature passing through the raw gas cooler 11 tube side is 10-20°C;

[0095] Step 6: The liquid phase at the bottom of the methanol analysis tower 15 is heated through the methanol cooler 16 pipe and pressurized by the methanol pump 17 and then sent to the methanol regeneration tower 18; the gas phase in the methanol regeneration tower 18 enters the acid gas treatment device 19 through the top gas phase outlet of the methanol regeneration tower 18 for acid gas treatment; the lean methanol liquid in the methanol regeneration tower 18 is sent to the lean methanol tank 21 through the lean methanol cooler 20; the lean methanol cooler 20 adopts a circulating water cooling method;

[0096] Step 7: The lean methanol liquid in the lean methanol tank 21 is pressurized by the lean methanol pump 22 and cooled in the shell side of the methanol cooler 16, and then sent to the methanol washing tower 12 through the lean methanol spray pipe inlet 27 for spraying; the lean methanol liquid pressure at the outlet of the lean methanol pump 22 is: 5.0-7.5MPa; the lean methanol liquid temperature at the shell side outlet of the methanol cooler 16 is: -55--62℃.

[0097] Furthermore, in step 2, there are two regenerated molecular sieves 7, which are in a state of mutual reserve;

[0098] When the first regenerated molecular sieve 7 is in an adsorption state, the second regenerated molecular sieve 7 is in a regeneration state;

[0099] When the second regenerated molecular sieve 7 is in the adsorption state, the first regenerated molecular sieve 7 is in the regeneration state;

[0100] When the regenerated molecular sieve 7 is in the adsorption state, the first valve 5 and the second valve 9 are in the open state, and the third valve 8 and the fourth valve 26 are in the closed state; the raw gas enters the regenerated molecular sieve 7 through the first valve 5 for adsorption, and the adsorbed raw gas is discharged from the regenerated molecular sieve 7 through the second valve 9;

[0101] When the regenerated molecular sieve 7 is in the regeneration state, the third valve 8 and the fourth valve 26 are in the open state, and the first valve 5 and the second valve 9 are in the closed state; the nitrogen in the molecular sieve regeneration gas storage tank 25 enters the regenerated molecular sieve 7 through the fourth valve 26 for regeneration, and the regenerated nitrogen enters the molecular sieve regeneration outlet system 28 through the third valve 8.

[0102] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connection", "connected" and the like should be understood in a broad sense. For example, it can be a fixed connection, an integral connection, or a detachable connection; it can also be the internal connection of two elements; it can be a direct connection, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The above examples are only specific descriptions of the feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent implementation methods, changes and modifications that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An anhydrous low-temperature methanol washing device, comprising a raw gas pipeline (1) and a methanol washing tower (12), characterized in that: The raw gas pipeline (1) is connected to the raw gas inlet of the methanol washing tower (12) through the raw gas dehydration unit. The top of the methanol washing tower (12) is connected to the purified gas pipe network (13); The liquid phase outlet at the bottom of the methanol washing tower (12) is connected to the lean methanol spray pipeline inlet (27) at the upper middle portion of the methanol washing tower (12) via a rich methanol treatment unit; The raw gas dehydration unit comprises at least one dehydration section; when there are multiple dehydration sections, the multiple dehydration sections are connected in series; The dehydration section comprises a precooler (2) and a water separation tank (3) connected to the precooler (2), and a condensate recovery tank (4) is provided at the bottom of the water separation tank (3); The dehydration section comprises at least one regenerated molecular sieve assembly, and when there are multiple regenerated molecular sieve assemblies, the multiple regenerated molecular sieve assemblies are connected in parallel; The regenerated molecular sieve assembly comprises a bottom portion of the regenerated molecular sieve (7) connected to a raw gas pipeline via a first tee (6) and a first valve (5), a top portion of the regenerated molecular sieve (7) connected to a gas outlet pipeline via a second tee (10) and a second valve (9), the first tee (6) connected to a molecular sieve regeneration gas outlet system (28) via a third valve (8), and the second tee (10) connected to a molecular sieve regeneration gas storage tank (25) via a fourth valve (26); The raw gas dehydration unit comprises a precooler (2) connected to a raw gas pipeline (1); the outlet of the precooler (2) is connected to a regenerated molecular sieve (7) via a water separation tank (3), a first valve (5), and a first tee (6); the outlet of the regenerated molecular sieve (7) is connected to a raw gas inlet of a methanol washing tower (12) via a second tee (10), a second valve (9), and a shell side of a raw gas cooler (11); and there are two regenerated molecular sieve assemblies; The rich methanol treatment unit comprises a medium-pressure flash tower (14) connected to a liquid phase outlet at the bottom of a methanol washing tower (12); the liquid phase outlet at the bottom of the medium-pressure flash tower (14) is connected to a methanol decomposition tower (15); the liquid phase outlet at the bottom of the methanol decomposition tower (15) is connected to a methanol regeneration tower (18) via a methanol cooler (16) pipe side and a methanol pump (17); the liquid phase outlet at the bottom of the methanol regeneration tower (18) is connected to a lean methanol spray pipeline inlet (27) via a lean methanol cooler (20), a lean methanol tank (21), a lean methanol pump (22) and a methanol cooler (16) shell side.

2. The anhydrous low-temperature methanol washing device according to claim 1 is characterized in that: The gas phase outlet at the top of the medium-pressure flash tower (14) is connected to the shell-side inlet of the raw gas cooler (11) through the circulating gas compressor (23); the gas phase outlet at the top of the methanol desorption tower (15) is connected to the desorption gas pipeline network (24) through the pipe side of the raw gas cooler (11); The gas phase outlet at the top of the methanol regeneration tower (18) is connected to the acid gas treatment device (19).

3. A production method of an anhydrous low-temperature methanol washing device, characterized in that: The production method comprises the following steps: Step 1: The raw gas in the raw gas pipeline (1) is cooled by the precooler (2) and then enters the water separation tank (3) for gas-liquid separation. The liquid phase after gas-liquid separation enters the condensate recovery tank (4); the temperature of the raw gas is 30-40°C, the pressure is 4.0-6.5MPa, and the molar fraction of water is 0.1%-0.2%; the temperature of the raw gas at the outlet of the precooler (2) is 5-10°C, and the cooling source of the precooler (2) is lithium bromide or ammonia cooling; Step 2: the raw gas after gas-liquid separation enters the regenerated molecular sieve (7) through the first valve (5) for re-dehydration, and the dehydrated raw gas enters the shell side of the raw gas cooler (11) through the second three-way valve (10) and the second valve (9); the water content of the raw gas at the outlet of the regenerated molecular sieve (7) is less than 1 ppm; Step 3: The raw gas is cooled in the shell side of the raw gas cooler (11) and enters the methanol scrubber (12). The lean methanol entering from the lean methanol spray pipe inlet (27) is sprayed. The gas phase after spraying enters the purified gas pipe network (13). The methanol-rich liquid at the bottom of the methanol scrubber (12) enters the medium-pressure flash tower (14) through the liquid phase outlet at the bottom of the methanol scrubber (12); The temperature of the raw gas at the shell outlet of the raw gas cooler (11) is -10--20°C; Step 4: The methanol-rich liquid solution enters the medium-pressure flash tower (14) and undergoes medium-pressure flash evaporation. The vapor after the medium-pressure flash evaporation is pressurized by the circulating gas compressor (23) and then returned to the shell side of the raw gas cooler (11) to repeat the above step 3. The liquid phase after the medium-pressure flash evaporation enters the methanol desorption tower (15); The flash pressure of the medium-pressure flash tower (14) is: 1.2-1.7 MPa; The circulating gas compressor (23) is a multi-stage centrifugal compressor with an inter-stage circulating water cooler, and the flash gas temperature at the outlet of the circulating gas compressor (23) is 20-40°C; Step 5: the liquid phase after the medium-pressure flash evaporation enters the methanol desorption tower (15) for desorption, and the gas phase enters the raw gas cooler (11) through the gas phase outlet at the top of the methanol desorption tower (15), exchanges heat with the raw gas in its shell side, and then enters the desorption gas pipe network (24); The bottom pressure of the methanol desorption tower (15) is 0.05-0.3 MPa; the temperature of the desorption gas passing through the tube side of the raw gas cooler (11) is 10-20°C; Step 6: the liquid phase at the bottom of the methanol analysis tower (15) is heated through the pipe side of the methanol cooler (16) and pressurized by the methanol pump (17) before being sent to the methanol regeneration tower (18); the gas phase in the methanol regeneration tower (18) enters the acid gas treatment device (19) through the gas phase outlet at the top of the methanol regeneration tower (18) for acid gas treatment; the lean methanol liquid in the methanol regeneration tower (18) is sent to the lean methanol tank (21) through the lean methanol cooler (20); the lean methanol cooler (20) adopts a circulating water cooling method; Step 7: The lean methanol liquid in the lean methanol tank (21) is pressurized by the lean methanol pump (22) and cooled in the shell side of the methanol cooler (16), and then sent to the methanol washing tower (12) through the lean methanol spray pipe inlet (27) for spraying; the lean methanol liquid pressure at the outlet of the lean methanol pump (22) is 5.0-7.5 MPa; the lean methanol liquid temperature at the shell side outlet of the methanol cooler (16) is -55°C to -62°C.

4. The production method of an anhydrous low-temperature methanol washing device according to claim 3, characterized in that: In step 2, there are two regenerated molecular sieves (7) which are in a standby state; When the first regenerated molecular sieve (7) is in an adsorption state, the second regenerated molecular sieve (7) is in a regeneration state; When the second regenerated molecular sieve (7) is in an adsorption state, the first regenerated molecular sieve (7) is in a regeneration state; When the regenerated molecular sieve (7) is in an adsorption state, the first valve (5) and the second valve (9) are in an open state, and the third valve (8) and the fourth valve (26) are in a closed state; the raw gas enters the regenerated molecular sieve (7) through the first valve (5) for adsorption, and the adsorbed raw gas is discharged from the regenerated molecular sieve (7) through the second valve (9); When the regenerated molecular sieve (7) is in a regenerating state, the third valve (8) and the fourth valve (26) are in an open state, and the first valve (5) and the second valve (9) are in a closed state; the nitrogen in the molecular sieve regeneration gas storage tank (25) enters the regenerated molecular sieve (7) through the fourth valve (26) for regeneration, and the regenerated nitrogen enters the molecular sieve regeneration gas outlet system (28) through the third valve (8).

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