Zero emission process in methanol synthesis process

Abstract

A methanol synthesis process zero emission technology comprises a methanol synthesis device, a membrane separation device, a fuel gas compressor and a PSA hydrogen extraction device, and the methanol synthesis device comprises a synthesis gas compressor, an online analyzer, a heat exchanger, a steam drum, a boiler feed pump, a synthesis tower, an air cooler, a water cooler, a high pressure methanol separator, a filter A and a flash tank. The membrane separation device comprises a filter B, a water scrubber, a coalescence filter, a heater, a membrane separator, a cooler and a high-pressure water pump, and the PSA hydrogen extraction device is used for treating permeated gas from the membrane separator to obtain a product hydrogen and desorbed gas; flash steam from the methanol synthesis device, tail gas from the membrane separation device and desorbed gas from the PSA hydrogen extraction device are recycled through the fuel gas compressor, waste gas generated in the methanol synthesis process can be completely recycled to the raw gas system again through a newly-added recycling machine, matched auxiliary equipment and a control system, methanol is synthesized again, and the production cost is reduced. And zero emission of the methanol synthesis device is realized.

Description

Technical Field

[0001] The invention relates to the technical field of methanol synthesis technology, and in particular to a zero-emission technology for methanol synthesis process. Background Art

[0002] Methanol is one of the basic chemical raw materials, mainly used to manufacture formaldehyde and pesticides, and can also be used as an organic solvent. The existing methanol synthesis reaction produces a large amount of flash gas and off-gas, of which H 2 ,CO,CO 2 , CH 4 High-energy gases are mainly used, and these high-energy gases are partially collected through hydrogen recovery devices or combustion, and some of them that cannot be recovered are vented to the flare system, but the above methods have low recovery rates, CO 2 The emission volume is high and the treatment effect is limited, which increases the production cost. Summary of the invention

[0003] In order to solve the defect that flash gas and purge gas in the existing methanol production technology are difficult to be completely recycled, the purpose of the present invention is to provide a zero-emission process for methanol synthesis.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a zero-emission process for methanol synthesis, including a methanol synthesis device, a membrane separation device, a fuel gas compressor 19 and a PSA hydrogen extraction device 20.

[0005] The methanol synthesis device comprises a synthesis gas compressor 1, an online analyzer 2, a heat exchanger 3, a steam drum 4, a boiler feed water pump 5, a synthesis tower 6, an air cooler 7, a water cooler 8, a high-pressure methanol separator 9, a filter A10, and a flash tank 11. The synthesis gas compressor 1 is connected to the shell side of the heat exchanger 3 through a pipeline, the online analyzer 2 is located on its pipeline, the heat exchanger 3 is connected to the synthesis tower 6, the top of the synthesis tower 6 is connected to the steam drum 4, the steam drum 4 is connected to the boiler feed water pump 5, the boiler feed water pump 5 is connected to the bottom of the synthesis tower 6, the tube side of the heat exchanger 3 is connected to the air cooler 7 through a pipeline, the air cooler 7 is connected to the high-pressure methanol separator 9 through the water cooler 8, the high-pressure methanol separator 9 is connected to the filter A10 and the methanol flash tank 11 in sequence, the flash gas in the methanol flash tank 11 is sent to the fuel gas compressor 19 through a pipeline, and the remaining liquid is sent to the methanol distillation device through a pipeline.

[0006] The membrane separation device includes a filter B12, a water scrubber 13, a coalescing filter 14, a heater 15, a membrane separator 16, a cooler 17, and a high-pressure water pump 18. The filter B12 is connected to the high-pressure methanol separator 9, the filter B12 is connected to the water scrubber 13, the water scrubber 13 is connected to the coalescing filter 14, the coalescing filter 14 is connected to the heater 15, the heater 15 is connected to the membrane separator 16, one end of the membrane separator 16 is connected to the cooler 17, and the other end is connected to the fuel gas compressor 19, the high-pressure water pump 18 is connected to the water scrubber 13, the PSA hydrogen extraction device 20 is connected to the cooler 17, and the PSA hydrogen extraction device 20 is connected to the fuel gas compressor 19 through a pipeline.

[0007] The fuel gas compressor 19 includes a Y-type filter A 1901, a Y-type filter B 1902, a separator A 1903, a separator B 1904, a separator C 1905, a separator D 1906, a separator E 1907, a separator F 1908, a separator H 1909, a separator J 1910, a separator K 1911, a primary cylinder A 1912, a secondary cylinder B 1913, a tertiary cylinder C 1914, a cooler A 1915, a cooler B 1916, a cooler C 1917, and a flash gas compressor 1918. The fuel gas compressor 19 is composed of a three-stage compression device. The separator A 1903, the primary cylinder A 1912, the separator B 1904, the cooler A 1915, and the separator C 1905 are sequentially connected to form a primary compression. The separator D 1906, the secondary cylinder B 1913, the tertiary cylinder C 1914, the cooler A 1915, the cooler B 1916, the cooler C 1917, and the flash gas compressor 1918. The separator H 1909, the third-stage cylinder C 1914, the separator J 1910, the cooler C 1917, and the separator K 1911 are sequentially connected to form a third-stage compression. The Y-type filter A 1901 receives flash gas from methanol synthesis and BDO, and the Y-type filter B 1902 receives analytical gas from the PSA hydrogen extraction device 20.

[0008] Furthermore, the outlet synthesis gas pressure of the synthesis gas compressor 1 is 8.8 MPa.

[0009] Furthermore, the heat exchanger 3 heats the synthesis gas to 210°C, and the heat exchanger 3 reduces the temperature of the methanol vapor to 126°C.

[0010] Furthermore, the air cooler 7 reduces the temperature of methanol to 70°C, and the water cooler 8 reduces the temperature of methanol to 40°C.

[0011] Furthermore, the crude alcohol is passed through a filter 10 to reduce the methanol pressure to 0.43 MPa.

[0012] Furthermore, the heater 15 uses 0.5 MPa, 158° C. low-pressure steam to raise the temperature of the raw gas by 60° C. and send it to the membrane separator 16 .

[0013] Furthermore, the membrane separator 16 separates the feed gas into two streams, one of which is 3.2 MPa permeate gas, namely, product hydrogen-rich gas; and the other is 0.6 MPa non-permeate gas, namely, tail gas.

[0014] Furthermore, the outlet temperature of the decomposed gas from the PSA hydrogen extraction device 20 is 40° C. and the pressure is 5-40 KPa.

[0015] Furthermore, the fuel gas compressor 19 is composed of three-stage compression. The decomposition gas from PSA has a temperature of 40°C and a pressure of 5~40KPa. It is sent to the fuel gas compressor 19 through an external pipe, filtered by the Y-type filter B 1902, and then merged with the two gases from the separator C1905 and the separator K1911 and sent to the separator A 1903. The gas temperature after filtration is 28°C, and the pressure in the container is 0.034MPa. It is then sent to the first-stage cylinder A 1912. After compression, the temperature rises to 75°C. The gas is sent to the separator B 1904, and the pressure in the container is 0.12MPa. After filtration, it enters the cooler A 1915, and after cooling, it enters the separator C 1905. A part of the gas separated from the top of the separator C 1905 is sent to the separator A together with the PSA decomposition gas. 1903, the other part enters separator D1906, the gas in separator D1906 is filtered and the temperature is 25℃, the pressure in the container is 0.11MPa, and then it is sent to the second-stage cylinder B1913, the temperature rises to 79℃ after compression, and it is sent to separator E1907, the pressure in the container is 0.25MPa, and it enters cooler B1916 after filtration, and enters separator F1908 after cooling; the flash gas from methanol synthesis (temperature 40℃, pressure 0.3MPa) and the flash gas from the membrane separation device (temperature 140℃, pressure 0.343MPa) are filtered by Y-type filter A 1901 and merged with the gas from separator K1911 and sent to separator F1908, the gas after filtration enters separator H1909, the gas temperature after filtration is 27℃, the pressure in the container is 0.24MPa, and then it is sent to the third-stage cylinder C 1914, after compression, the temperature rises to 129℃, the pressure rises to 0.8MPa, and is sent to separator J1910. The pressure in the container is 0.68MPa. After filtration, the temperature drops to 35℃ through cooler C 1917, and the liquid is separated by separator K1911 and sent to flash gas compressor 1918.

[0016] Compared with the existing methanol synthesis device, the present invention has the following advantages.

[0017] The zero-emission process of methanol synthesis process of the present invention monitors and analyzes the content and components of synthesis gas in real time through an online analyzer 2, which is helpful to feedback the operation status of the equipment, realize active early warning of faults, ensure pipeline safety, and improve process stability.

[0018] The invention discloses a zero-emission process for methanol synthesis, which realizes heat exchange between inlet gas and process gas containing methanol vapor at the outlet of a synthesis tower in the shell side and tube side of a heat exchanger.

[0019] In the zero-emission process for methanol synthesis of the present invention, most of the gas separated from the top of the high-pressure methanol separator 9 is returned to the circulation section of the synthesis gas compressor 1 and recycled after being pressurized; a small part is sent to the PSA hydrogen recovery device 18, thereby preventing the accumulation of inert gas, saving costs and improving the yield.

[0020] In the zero-emission process of methanol synthesis process of the present invention, the membrane separator 16 removes a small amount of liquid foam carried by the raw gas by using a high-precision coalescing filter element with an accuracy of 1 μm, thereby reducing damage to the membrane and greatly extending the life of the membrane separator 16.

[0021] The zero-emission process of methanol synthesis of the present invention ensures the temperature of the raw gas by adding a heater 15 after the coalescing filter 14, avoids condensation of water vapor after concentration on the permeate side of the membrane separator 16, and also enables the separator to be in the most optimized working state.

[0022] The zero-emission process for methanol synthesis of the present invention separates the pretreated raw gas into two streams through a membrane separator 16, one of which is a 3.2MPa permeate gas, i.e., product hydrogen, and the other is a 0.6MPa non-permeate gas, i.e., tail gas. The permeate gas enters the product stream and is sent to a PSA hydrogen extraction device 20, and the tail gas is used as fuel for a fuel gas compressor 19, thereby improving the utilization rate of the raw materials.

[0023] A zero-emission process for a methanol synthesis process of the present invention processes hydrogen-rich permeate gas from a membrane separator 16 through a PSA hydrogen extraction device 20 to obtain product hydrogen and desorption gas; flash gas from a methanol synthesis device, tail gas from a membrane separation device and desorption gas generated by the PSA hydrogen extraction device 20 are recycled through a fuel gas compressor 19; and waste gas generated in the methanol synthesis process can be completely recycled to a raw gas system through a newly added recycling machine and supporting auxiliary equipment and a control system to be resynthesized to generate methanol, thereby achieving zero-emission for the methanol synthesis device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a simplified material flow diagram of a recovery system for a zero-emission process of a methanol synthesis process.

[0025] Figure 2This is a gas circuit diagram of a fuel gas compressor 19 in a zero-emission process of a methanol synthesis process of the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "top", "bottom", "one side", "the other side", "front", "back", "middle part", "inside", "top end", "bottom end", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention is further described in detail below with reference to the accompanying drawings. Example

[0029] like Figure 1 Figure 2 As shown, a zero-emission process for methanol synthesis includes a methanol synthesis unit, a membrane separation unit, a fuel gas compressor 19 and a PSA hydrogen extraction unit 20.

[0030] The methanol synthesis device comprises a synthesis gas compressor 1, an online analyzer 2, a heat exchanger 3, a steam drum 4, a boiler feed water pump 5, a synthesis tower 6, an air cooler 7, a water cooler 8, a high-pressure methanol separator 9, a filter A10, and a flash tank 11. The membrane separation device comprises a filter B12, a water washing tower 13, a coalescing filter 14, a heater 15, a membrane separator 16, a cooler 17, and a high-pressure water pump 18. The fuel gas compressor 19 comprises a Y-type filter A1901, a Y-type filter B1902, a separator A1903, a separator B1904, a separator C1905, a separator D1906, a separator E1907, a separator F1908, a separator H1909, a separator J1910, a separator K1911, a first-stage cylinder A1912, a second-stage cylinder B1913, a third-stage cylinder C1914, a cooler A1915, a second-stage cylinder B1916, a third-stage cylinder C1917, a third-stage cylinder C1918, a third-stage cylinder C1919, a third-stage cylinder C1920, a third-stage cylinder C1921, a third-stage cylinder C1922, a third-stage cylinder C1923, a third-stage cylinder C1924, a third-stage cylinder C1925, a third-stage cylinder C1926, a third-stage cylinder C1927, a third-stage cylinder C1928, a third-stage cylinder C1929, a third-stage cylinder C1930, a third-stage cylinder C1931, a third-stage cylinder C1932, a third-stage cylinder C1933, a third-stage cylinder C1934, a third-stage cylinder C1935, a third-stage cylinder 1915. Cooler B 1916. Cooler C 1917. Flash gas compressor 1918.

[0031] The synthesis gas compressor 1 raises the pressure of the fresh synthesis gas to 8.8MPa, and the online analyzer 2 monitors and analyzes the content and components of the synthesis gas in real time, and then feeds back the operating status of the equipment before entering the heat exchanger 3 shell side, where the outlet gas is heated to 210°C and then enters the synthesis tower 6, where methanol is generated by reaction under the action of the catalyst; the process gas with methanol vapor at the outlet of the synthesis tower 6 exchanges heat with the inlet gas through the tube side of the heat exchanger 3, and after the temperature drops to 126°C, it enters the air cooler 7 and is further cooled to 70°C, at which time most of the methanol has been condensed, and then enters the water cooler 8 to be cooled to 40°C, at which time a small part of the methanol has been condensed, and the vapor-liquid mixture at 40°C is separated into crude alcohol by the high-pressure methanol separator 9; the crude alcohol is filtered by the filter A10, depressurized to 0.43MPa, and enters the methanol flash tank 11 for flash evaporation to remove most of the gas dissolved in the methanol, and this part of the flash gas is sent to the fuel gas compressor 19, and the remaining liquid is sent to the methanol distillation device through the pipeline.

[0032] A part of the gas separated from the top of the high-pressure methanol separator 9 is returned to the circulation section of the synthesis gas compressor 1, and is recycled after being pressurized; the other part enters the filter B12 after adjustment, and the solid and liquid particles entrained in the raw gas are removed by a stainless steel filter element with a filtration accuracy of 10µm. The solid particles may be generated by oligomers, which will cause serious blockage to the subsequent water washing tower fillers and coalescing filter elements. After filtration, it enters the water washing tower 13, and contacts with the desalted water in countercurrent through the stainless steel structured fillers to recover the methanol component in the raw gas. The low-pressure desalted water is pressurized by the high-pressure water pump 18 and enters the top of the water washing tower. The raw gas leaving the top of the water washing tower 13 carries a small amount of liquid foam and enters the coalescing filter 14. The liquid and solid particles are removed by the coalescing filter element with a precision of 1µm. The particles may permanently damage the membrane fiber, and the particles must be removed to ensure that the membrane is not blocked; the raw gas leaving the coalescing filter 14 The gas contains saturated water vapor at this temperature and composition. In order to avoid condensation of water vapor after concentration on the permeate side of the membrane separator 16 and to optimize the working state of the membrane separator 16, a heater 15 is provided. Low-pressure steam of 0.5 MPa and 158°C is used to heat the raw gas to an operating temperature of 60°C. The raw gas after pretreatment and adjustment enters the membrane separator 16. The membrane separator 16 separates the pretreated raw gas into two streams, one is a permeate gas of 3.2 MPa, i.e., product hydrogen, and the other is a non-permeate gas of 0.6 MPa, i.e., tail gas; the product hydrogen enters the cooler 17 to be cooled to 40°C and then is sent to the PSA hydrogen extraction device 20 for further hydrogen extraction treatment. After treatment, product hydrogen and PSA analytical gas are obtained. The PSA analytical gas is sent to the first-level inlet of the fuel gas compressor 19 through a pipeline and recycled after pressure increase. The tail gas stream of the membrane separator 16 is sent to the fuel gas compressor 19.

[0033] The fuel gas compressor 19 is composed of three-stage compression. The analytical gas from PSA, with a temperature of 40°C and a pressure of 5~40KPa, is sent to the fuel gas compressor 19 through an external pipe, filtered by a Y-type filter B 1902, and then merged with the two gases from the separator C 1905 and the separator K1911 and sent to the separator A 1903. The gas temperature after filtration is 28°C, and the pressure in the container is 0.034MPa. It is then sent to the first-stage cylinder A 1912. After compression, the temperature rises to 75°C. The gas is sent to the separator B 1904, and the pressure in the container is 0.12MPa. After filtration, it enters the cooler A 1915, and after cooling, it enters the separator C 1905. A part of the gas separated from the top of the separator C 1905 is sent to the separator A together with the analytical gas from PSA. 1903, the other part enters separator D1906, the gas in separator D1906 is filtered and the temperature is 25℃, the pressure in the container is 0.11MPa, and then it is sent to the second-stage cylinder B1913, the temperature rises to 79℃ after compression, and it is sent to separator E1907, the pressure in the container is 0.25MPa, and it enters cooler B1916 after filtration, and enters separator F1908 after cooling; the flash gas from methanol synthesis (temperature 40℃, pressure 0.3MPa) and the flash gas from the membrane separation device (temperature 140℃, pressure 0.343MPa) are filtered by Y-type filter A 1901 and merged with the gas from separator K1911 and sent to separator F1908, the gas after filtration enters separator H1909, the gas temperature after filtration is 27℃, the pressure in the container is 0.24MPa, and then it is sent to the third-stage cylinder C 1914, after compression, the temperature rises to 129℃, the pressure rises to 0.8MPa, and is sent to separator J1910. The pressure in the container is 0.68MPa. After filtration, the temperature drops to 35℃ through cooler C 1917, and the liquid is separated by separator K1911 and sent to flash gas compressor 1918. After three-stage compression, it can not only improve the cycle efficiency and reduce energy consumption, but also greatly remove impurities in the gas, thereby improving the purity of the gas.

[0034] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0035] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A zero-emission process for methanol synthesis, characterized in that It comprises a methanol synthesis device, a membrane separation device, a fuel gas compressor (19) and a PSA hydrogen extraction device (20); The methanol synthesis device comprises a synthesis gas compressor (1), an online analyzer (2), a heat exchanger (3), a steam drum (4), a boiler feed water pump (5), a synthesis tower (6), an air cooler (7), a water cooler (8), a high-pressure methanol separator (9), a filter A (10), and a flash tank (11). The synthesis gas compressor (1) is connected to the shell side of the heat exchanger (3) through a pipeline, the online analyzer (2) is located on the pipeline, the heat exchanger (3) is connected to the synthesis tower (6), and the top of the synthesis tower (6) is connected to the steam drum (4). The drum (4) is connected to a boiler feed water pump (5), the boiler feed water pump (5) is connected to the bottom of a synthesis tower (6), the tube side of the heat exchanger (3) is connected to an air cooler (7) through a pipeline, the air cooler (7) is connected to a high-pressure methanol separator (9) through a water cooler (8), the high-pressure methanol separator (9) is connected to the crude alcohol through a filter A (10) and a methanol flash tank (11) in sequence, the flash gas in the methanol flash tank (11) is sent to a fuel gas compressor (19) through a pipeline, and the remaining liquid is sent to a methanol distillation device through a pipeline; The membrane separation device comprises a filter B (12), a water washing tower (13), a coalescing filter 14, a heater (15), a membrane separator (16), a cooler (17), and a high-pressure water pump (18); the filter B (12) is connected to the high-pressure methanol separator (9); the filter B (12) is connected to the water washing tower (13); the water washing tower (13) is connected to the coalescing filter (14); the coalescing filter (14) is connected to the heater (15); the heater (15) is connected to the membrane separator (16); one end of the membrane separator (16) is connected to the cooler (17) and the other end is connected to the fuel gas compressor (19); the high-pressure water pump (18) is connected to the water washing tower (13); the PSA hydrogen extraction device (20) is connected to the cooler (17); and the PSA hydrogen extraction device (20) is connected to the fuel gas compressor (19) via a pipeline; The fuel gas compressor (19) comprises a Y-type filter A (1901), a Y-type filter B (1902), a separator A (1903), a separator B (1904), a separator C (1905), a separator D (1906), a separator E (1907), a separator F (1908), a separator H (1909), a separator J (1910), a separator K (1911), a primary cylinder A (1912), a secondary cylinder B (1913), a tertiary cylinder C (1914), a cooler A (1915), a cooler B (1916), a cooler C (1917), and a flash gas compressor (1918). The fuel gas compressor compression device comprises a three-stage compression device. The separator A (1903), the primary cylinder A (1912), the secondary cylinder B (1913), the tertiary cylinder C (1914), a cooler A (1915), a cooler B (1916), a cooler C (1917), and a flash gas compressor (1918). (1912), separator B (1904), cooler A (1915), and separator C (1905) are connected in sequence to form a first-stage compression; the separator D (1906), secondary cylinder B (1913), separator E (1907), cooler B (1916), and separator F (1908) are connected in sequence to form a second-stage compression; the separator H (1909), tertiary cylinder C (1914), separator J (1910), cooler C (1917), and separator K (1911) are connected in sequence to form a tertiary compression; the Y-type filter A (1901) receives flash gas generated from methanol synthesis and BDO, and the Y-type filter B (1902) receives analytical gas from the PSA hydrogen extraction device (20).

2. A zero-emission process for methanol synthesis according to claim 1, characterized in that The syngas pressure at the outlet of the syngas compressor (1) is 8.8 MPa.

3. A zero-emission process for methanol synthesis according to claim 1, characterized in that The heat exchanger (3) heats the synthesis gas to 210°C, and the heat exchanger (3) reduces the temperature of the methanol vapor to 126°C.

4. A zero-emission process for methanol synthesis according to claim 1, characterized in that The air cooler (7) reduces the temperature of methanol to 70°C, and the water cooler (8) reduces the temperature of methanol to 40°C.

5. A zero-emission process for methanol synthesis according to claim 1, characterized in that The crude alcohol is passed through a filter (10) to reduce the methanol pressure to 0.43 MPa.

6. A zero-emission process for methanol synthesis according to claim 1, characterized in that The heater (15) uses 0.5 MPa, 158°C low-pressure steam to raise the temperature of the raw gas by 60°C and send it to the membrane separator (16).

7. A zero-emission process for methanol synthesis according to claim 1, characterized in that The membrane separator (16) separates the raw gas into two streams, one of which is a permeate gas at 3.2 MPa, i.e., the product hydrogen-rich gas; and the other is a non-permeate gas at 0.6 MPa, i.e., the tail gas.

8. A zero-emission process for methanol synthesis according to claim 1, characterized in that The outlet temperature of the decomposed gas of the PSA hydrogen extraction device (20) is 40°C and the pressure is 5-40KPa.

9. A zero-emission process for methanol synthesis according to claim 1, characterized in that The fuel gas compressor (19) is composed of three-stage compression. The decomposition gas from PSA has a temperature of 40°C and a pressure of 5~40KPa. It is sent to the fuel gas compressor (19) through an external pipe, filtered by a Y-type filter B (1902), and then merged with the two gases from separator C (1905) and separator K (1911) and sent to separator A (1903). The temperature of the gas after filtration is 28°C, and the pressure in the container is 0.034MPa. It is then sent to a first-stage cylinder A (1912). After compression, the temperature rises to 75°C. The gas is sent to separator B (1904), and the pressure in the container is 0.12MPa. After filtration, it enters cooler A (1915), and after cooling, it enters separator C (1905). A part of the gas separated from the top of separator C (1905) is sent to separator A together with the decomposition gas from PSA. (1903), the other part enters separator D (1906), the gas in separator D (1906) is filtered and the temperature is 25℃, the pressure in the container is 0.11MPa, and then it is sent to the secondary cylinder B (1913), after compression, the temperature rises to 79°C, and is sent to separator E (1907), the pressure in the container is 0.25MPa, after filtration, it enters cooler B (1916), and after cooling, it enters separator F (1908); the flash gas from methanol synthesis (temperature 40°C, pressure 0.3MPa) and the flash gas from the membrane separation device (temperature 140°C, pressure 0.343MPa) are filtered by Y-type filter A (1901) and merged with the gas from separator K (1911) and sent to separator F (1908). After filtration, the gas enters separator H (1909). The temperature of the gas after filtration is 27°C, and the pressure in the container is 0.24MPa, and then it is sent to the three-stage cylinder C (1914). After compression, the temperature rises to 129°C and the pressure rises to 0.8MPa, and it is sent to separator J (1910), the pressure in the container is 0.68MPa, and after filtration, it passes through cooler C (1917) The temperature drops to 35°C, and the liquid is separated from it by separator K (1911) and then sent to the flash gas compressor (1918).

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