System for preparing high-pressure CO2 gas through low-temperature methanol washing

Abstract

The invention relates to the technical field of coal chemical industry production, in particular to a system for preparing high-pressure CO2 gas through low-temperature methanol washing, which comprises a shift gas washing tower, a liquid CO2 evaporation heat exchanger, a desulfurization shift gas separation tank, a medium-pressure flash tank and a shift gas cooler, and the exhaust end of the shift gas washing tower is connected with the gas inlet end of the liquid CO2 evaporation heat exchanger after being subjected to heat exchange and cooling by the heat exchange system. A part of shift gas after H2S, COS, part of CO2 and other components are removed through a shift gas washing tower A section is led out, the temperature is further reduced through a heat exchanger, then the principle of liquefaction, reduced pressure flash evaporation and vaporization is fully utilized, a small amount of H2 and CO gas dissolved in liquid CO2 is recycled and vaporized, high-pressure CO2 product gas is prepared and obtained, the high-pressure CO2 product gas is sent to a rear workshop section to be subjected to centrifugal CO2 compression for use, and the high-pressure CO2 product gas is recycled. The centrifugal C02 compressor is changed into three-stage compression from original four-stage compression, so that the manufacturing cost of the centrifugal C02 compressor is saved, the operation power consumption is reduced, and the energy-saving and consumption-reducing effects are obvious.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal chemical production, and particularly relates to a low-temperature methanol washing system for preparing high-pressure CO2 gas. BACKGROUND

[0002] In the low-temperature methanol washing process of the coal chemical production process, the absorption of H2S, COS and CO2 and other acid gases, the regeneration of the solution after absorption and the desorption of H2, CO and other useful gases with low solubility are based on the different solubilities of various gases in methanol under different conditions. According to this characteristic, the methods of staged decompression, inert gas (nitrogen) stripping or heating regeneration desorption can be used to recover the dissolved useful gases and obtain CO2 product gas, H2S acid gas and vent tail gas.

[0003] The dissolved CO2 gas is desorbed at low pressure (normal pressure or even negative pressure), and the lower the pressure, the greater the desorption amount and the more the recovered CO2 product. However, too low pressure will cause difficulty in CO2 gas transportation. The product gas pressure of the CO2 product obtained by desorption in the original low-temperature methanol washing device is generally 0.1-0.2 MPa when sent to the centrifugal CO2 compressor, which increases the operation power consumption and manufacturing cost of the centrifugal CO2 compressor and is not conducive to the energy saving and consumption reduction of the space furnace production device. Therefore, the present application provides a low-temperature methanol washing system for preparing high-pressure CO2 gas. SUMMARY

[0004] The present application aims to solve the problem of the increase of the operation power consumption and manufacturing cost of the centrifugal CO2 compressor in the prior art, which is not conducive to the energy saving and consumption reduction of the space furnace production device. The present application provides a low-temperature methanol washing system for preparing high-pressure CO2 gas, which can save the manufacturing cost of the centrifugal CO2 compressor and the operation power consumption, and has obvious energy saving and consumption reduction effect.

[0005] In order to achieve the above-mentioned purpose, the low-temperature methanol washing system for preparing high-pressure CO2 gas comprises a shift gas washing tower, a liquid CO2 evaporation heat exchanger, a desulfurized shift gas separation tank, a medium-pressure flash tank and a shift gas cooler, the exhaust end of the shift gas washing tower is connected with the gas inlet end of the liquid CO2 evaporation heat exchanger after heat exchange and temperature reduction by a heat exchange system, the liquid outlet end of the liquid CO2 evaporation heat exchanger is connected with the liquid inlet end of the desulfurized shift gas separation tank, the liquid outlet end of the desulfurized shift gas separation tank is connected with the liquid inlet end of the medium-pressure flash tank, the gas outlet end of the medium-pressure flash tank is connected with the gas inlet end of the medium-pressure flash tower, the liquid outlet end of the medium-pressure flash tank is connected with the liquid inlet end of the liquid CO2 evaporation heat exchanger, and the gas outlet end of the liquid CO2 evaporation heat exchanger is connected with the gas inlet end of the centrifugal CO2 compressor after heat exchange and temperature increase by the shift gas cooler.

[0006] As a further description of the above technical solution: the heat exchange system comprises a desulfurization shift gas cooler and a desulfurization shift gas ammonia cooler, the exhaust end of the shift gas washing tower is connected with the desulfurization shift gas cooler and the desulfurization shift gas ammonia cooler respectively through pipelines, and the exhaust ends of the desulfurization shift gas cooler and the desulfurization shift gas ammonia cooler are connected with the gas inlet end of the liquid CO2 evaporation heat exchanger.

[0007] As a further description of the above technical solution: the exhaust end of the desulfurization shift gas separation tank is connected with the gas inlet end of the shift gas washing tower through a gas return pipeline.

[0008] As a further description of the above technical solution: the pipeline comprises an exhaust pipeline, the end of the exhaust pipeline is connected with a first gas pipe and a second gas pipe, the first gas pipe is connected with the gas inlet end of the desulfurization shift gas cooler, and the second gas pipe is connected with the gas inlet end of the desulfurization shift gas ammonia cooler.

[0009] As a further description of the above technical solution: a first remote DCS regulating valve is arranged on the pipeline connecting the medium-pressure flash tank with the medium-pressure flash tower.

[0010] As a further description of the above technical solution: an SIS control valve is arranged on the pipeline connecting the desulfurization shift gas separation tank with the medium-pressure flash tank.

[0011] As a further description of the above technical solution: a first DCS liquid level automatic regulating valve group is arranged on the pipeline connecting the desulfurization shift gas separation tank with the medium-pressure flash tank, the first DCS liquid level automatic regulating valve group is associated with the liquid level of the desulfurization shift gas separation tank, and remote automatic control operation is realized.

[0012] As a further description of the above technical solution: a second DCS liquid level automatic regulating valve group is arranged on the pipeline connecting the medium-pressure flash tank with the liquid CO2 evaporation heat exchanger, the second DCS liquid level automatic regulating valve group is associated with the liquid level of the medium-pressure flash tank, and remote automatic control operation is realized.

[0013] As a further description of the above technical solution: a second remote DCS regulating valve is arranged on the pipeline connecting the shift gas cooler with the centrifugal CO2 compressor.

[0014] As a further description of the above technical solution: the shift gas washing tower has four sections A, B, C and D, the exhaust end of the section A of the shift gas washing tower is connected with the heat exchange system, and the gas inlet end of the section B of the shift gas washing tower is connected with the exhaust end of the desulfurization shift gas separation tank.

[0015] The above technical solution has the following advantages or beneficial effects:

[0016] The application introduces part of the shift gas after removing H2S, COS and part of CO2 and other components in the shift gas washing tower section A, further reduces the temperature through the heat exchanger, fully utilizes the liquefaction, pressure reduction flash evaporation and vaporization principles, recovers a small amount of H2 and CO gas dissolved in liquid CO2, vaporizes after recovery, prepares high-pressure CO2 product gas, and sends to the centrifugal CO2 compressor for use, so that the centrifugal CO2 compressor is changed from the original four-stage compression to three-stage compression, which not only saves the manufacturing cost of the centrifugal CO2 compressor, but also saves the operation power consumption, the energy saving and consumption reduction effect is obvious, the operation efficiency of the space furnace production device is improved, and the production benefit is also improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a structure schematic diagram of a low-temperature methanol washing system for preparing high-pressure CO2 gas in one embodiment of the application.

[0018] LEGEND:

[0019] 1, shift gas washing tower; 2, desulfurized shift gas cooler; 3, desulfurized shift gas ammonia cooler; 4, liquid CO2 evaporation heat exchanger; 5, desulfurized shift gas separation tank; 6, medium-pressure flash tank; 7, shift gas cooler; 8, medium-pressure flash tower; 9, centrifugal CO2 compressor; 10, gas return pipeline; 11, gas outlet pipeline; 111, first gas pipe; 112, second gas pipe; 12, communication pipe; 13, control valve; 14, first remote DCS regulating valve; 15, SIS control valve; 16, first DCS liquid level automatic regulating valve group; 17, second DCS liquid level automatic regulating valve group; 18, second remote DCS regulating valve. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0021] In the description of the application, it should be noted that the orientations or positional relationships indicated by the terms "vertical", "upper", "lower", "horizontal" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0022] In the description of the present application, it is also necessary to explain that, unless otherwise explicitly specified and limited, the terms "set", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0023] Please refer to Figure 1 The present application provides a technical solution: a low-temperature methanol washing system for preparing high-pressure CO2 gas, comprising a shift gas washing tower 1, a liquid CO2 evaporation heat exchanger 4, a desulfurized shift gas separation tank 5, a medium-pressure flash tank 6 and a shift gas cooler 7. The exhaust end of the shift gas washing tower 1 is connected to the gas inlet end of the liquid CO2 evaporation heat exchanger 4 after heat exchange and cooling by a heat exchange system. The liquid outlet end of the liquid CO2 evaporation heat exchanger 4 is connected to the desulfurized shift gas separation tank 5. The liquid outlet end of the desulfurized shift gas separation tank 5 is connected to the liquid inlet end of the medium-pressure flash tank 6. The gas outlet end of the medium-pressure flash tank 6 is connected to the gas inlet end of a medium-pressure flash tower 8. The liquid outlet end of the medium-pressure flash tank 6 is connected to the liquid inlet end of the liquid CO2 evaporation heat exchanger 4. The gas outlet end of the liquid CO2 evaporation heat exchanger 4 is connected to the gas inlet end of a centrifugal CO2 compressor 9 after heat exchange and temperature rise by the shift gas cooler 7. Cut-off valves are installed on each pipeline to control the opening and closing device.

[0024] In the technical solution of the present application, the shift gas after removing H2S, COS and part of CO2 and other components in the shift gas washing tower 1 enters the heat exchange system for cooling and temperature reduction. After heat exchange and temperature reduction by the heat exchange system, it enters the liquid CO2 evaporation heat exchanger 4 for evaporation heat exchange with condensed CO2. After further temperature reduction, it enters the desulfurized shift gas separation tank 5 to separate out CO2 condensate. The liquid phase in the desulfurized shift gas separation tank 5 enters the medium-pressure flash tank 6. The medium-pressure flash tank 6 flashes out H2 and CO containing a small amount of H2 and CO, which are recovered to the medium-pressure flash tower 8. The liquid phase in the medium-pressure flash tank 6 enters the liquid CO2 evaporation heat exchanger 4 after heat exchange with the desulfurized shift gas and vaporization, and high-pressure CO2 product gas is obtained. The obtained high-pressure CO2 product gas is heated and raised in temperature to 15-25℃ by the shift gas cooler 7 and sent to the centrifugal CO2 compressor 9 for use. The centrifugal CO2 compressor is changed from the original four-stage compression to three-stage compression, which not only saves the manufacturing cost of the centrifugal CO2 compressor, but also saves the operating power consumption, and the energy saving and consumption reduction effect is obvious. The operation efficiency of the space furnace production device is improved, and the production benefit is also improved.

[0025] The purity of the high-pressure CO2 product gas is C02≥98.5% (vol) (dry basis), and the pressure is 0.5-0.7 MPa (G).

[0026] For example Figure 1As shown, the heat exchange system includes a desulfurized shift gas cooler 2 and a desulfurized shift gas ammonia cooler 3, and the exhaust end of the shift gas washing tower 1 is connected to the desulfurized shift gas cooler 2 and the desulfurized shift gas ammonia cooler 3 through pipelines, respectively, and the exhaust ends of the desulfurized shift gas cooler 2 and the desulfurized shift gas ammonia cooler 3 are connected to the gas inlet end of the liquid CO2 evaporation heat exchanger 4.

[0027] Specifically, the shift gas after removing H2S, COS and part of CO2 and other components in the shift gas washing tower 1 is divided into two paths when discharged, one path enters the desulfurized shift gas cooler 2 to exchange heat with synthesis gas, purified gas, CO2 gas and tail gas for cooling, and the other path enters the desulfurized shift gas ammonia cooler 3 for cooling. After heat exchange and cooling in the desulfurized shift gas cooler 2 and the desulfurized shift gas ammonia cooler 3, the shift gas is combined and enters the liquid CO2 evaporation heat exchanger 4 to exchange heat with condensed CO2 for further temperature reduction, and then enters the desulfurized shift gas separation tank 5 to separate out CO2 condensate. The shift gas is exchanged with different media in two paths, and in the desulfurized shift gas cooler 2, heat exchange is performed with synthesis gas, purified gas, CO2 gas and tail gas, which can fully utilize the waste heat of these gases, realize heat recovery and exchange, reduce the temperature of the shift gas, and avoid waste of heat. In the desulfurized shift gas ammonia cooler 3, cooling is performed by ammonia cooling, which has the characteristics of high refrigeration efficiency and fast cooling speed. The two different cooling methods make the shift gas be cooled more quickly and effectively to a suitable temperature, enhance the solubility of CO2 in methanol, and thus make it easier to realize the condensation of CO2 when entering the liquid CO2 evaporation heat exchanger, improve the separation efficiency of CO2 and other gases, and ensure the yield and purity of the final high-pressure CO2 product gas.

[0028] Among them, the two-path heat exchange method can more accurately control the heat exchange process according to the characteristics and temperature requirements of different gases. In the desulfurized shift gas cooler, the waste heat of other gases is used to preliminarily cool the shift gas, reducing the consumption of additional refrigeration energy; the desulfurized shift gas ammonia cooler performs deep refrigeration as needed on the basis of preliminary cooling, avoiding the energy waste caused by single ammonia cooling for substantial cooling. This phased and targeted cooling method can significantly reduce the energy consumption of the entire heat exchange system compared to the traditional single cooling method, reduce operating costs, and meet the production needs of energy saving and consumption reduction. The two-path heat exchange design makes the system more flexible when facing different working conditions and production demands. When the composition and flow of the raw gas change, or the production process has special requirements for temperature control, the operating parameters of the two heat exchange equipment can be adjusted, such as controlling the gas flow ratio entering the desulfurized shift gas cooler and the desulfurized shift gas ammonia cooler, or adjusting the refrigeration intensity of the ammonia cooler, to flexibly adjust the cooling process of the shift gas, so that the system can quickly adapt to changes and ensure the stable operation and production efficiency of the entire low-temperature methanol wash system for producing high-pressure CO2.

[0029] As shown in Figure 1 The exhaust end of the desulfurized shift gas separation tank 5 is connected with the gas inlet end of the shift gas washing tower 1 through the gas return pipeline 10; the gas phase of the desulfurized shift gas separation tank 5 returns to the shift gas washing tower 1 for further washing, and the liquid phase enters the medium-pressure flash tank 6. The gas phase separated by the desulfurized shift gas separation tank 5 still contains CO2 and other recyclable gas components that are not completely separated. Returning this part of the gas phase to the shift gas washing tower through the gas return pipeline 10 can make it participate in the washing and absorption process again, fully utilize the effective components in the raw material gas, and avoid the waste of resources caused by the direct discharge of these not fully utilized gases. Through recycling, the overall utilization rate of the raw material gas is improved, the production cost is reduced, and the maximum utilization of resources is realized.

[0030] Specifically, the pipeline between the shift gas washing tower 1 and the heat exchange system includes a gas outlet pipeline 11, the end of which is connected with a first gas pipe 111 and a second gas pipe 112, the first gas pipe 111 is connected with the gas inlet end of the desulfurized shift gas cooler 2, and the second gas pipe 112 is connected with the gas inlet end of the desulfurized shift gas ammonia cooler 3; the gas outlet pipeline 11 is connected with the gas return pipeline 10 through a communication pipe 12, and the communication pipe 12 is provided with a control valve 13. The first gas pipe 111 and the second gas pipe 112 connected with the end of the gas outlet pipeline 11 can flexibly distribute the gas discharged from the shift gas washing tower to the desulfurized shift gas cooler 2 and the desulfurized shift gas ammonia cooler 3. By adjusting the gas flow ratio entering the two different heat exchange equipment, the cooling process of the shift gas can be accurately controlled according to the actual production demand and working condition change. For example, when the raw material gas temperature is relatively high or the composition is special, the cooling requirement is more stringent, the gas flow entering the desulfurized shift gas ammonia cooler can be appropriately increased to strengthen the refrigeration effect; on the contrary, if the working condition is relatively stable, the flow can be reasonably distributed to reduce the energy consumption while ensuring the cooling effect, realize the precise and individualized heat exchange operation, and improve the adaptability of the system to different production conditions.

[0031] The communication pipe 12 and the control valve 13 are arranged, so that the system can conveniently adjust the process during operation. When the system needs to be overhauled, the process is adjusted, or the sudden situation is coped with, the opening and closing and flow of the communication pipe 12 can be controlled through the control valve 13 to flexibly change the gas flow direction. At the same time, it is also convenient to optimize the process flow according to the actual demand in the production process, and improve the overall performance of the system.

[0032] The pipeline connection mode organically combines the shift gas washing tower 1, the heat exchange system and the gas return pipeline 10 to form a highly integrated whole, and enhances the synergy between the parts of the system. The gas flows more smoothly between different devices and pipelines, and the links can better cooperate and work together. For example, in the gas distribution and heat exchange process, the gas distribution of the gas outlet pipeline 11 can be adjusted in real time according to the state of the return gas of the gas return pipeline 10 through the regulating valve 13, so as to realize the dynamic balance of the washing, heat exchange, separation and other links, fully exert the overall efficiency of the system, and improve the operation efficiency and comprehensive performance of the whole low-temperature methanol washing system for preparing high-pressure CO2.

[0033] The medium-pressure flash tank 6 flashes out the H2 and CO containing a small amount of H2 and CO to the medium-pressure flash tower 8, and the flash gas pressure is controlled at 1.3-1.4 MPa.

[0034] As shown in Figure 1 , the SIS control valve 15 is arranged on the pipeline between the desulfurized shift gas separation tank 5 and the medium-pressure flash tank 6; the SIS control valve 15 arranged on the pipeline between the liquid phase of the desulfurized shift gas separation tank 5 and the medium-pressure flash tank 6 is used to prevent the 3.3 MPa gas in the desulfurized shift gas separation tank 5 from entering the medium-pressure flash tank 6, and to protect the safety of the medium-pressure flash tank 6.

[0035] As shown in Figure 1 , the first DCS liquid level automatic regulating valve group 16 is arranged on the pipeline between the desulfurized shift gas separation tank 5 and the medium-pressure flash tank 6, the first DCS liquid level automatic regulating valve group 16 is associated with the liquid level of the desulfurized shift gas separation tank 5, and remote automatic control operation is realized; the second DCS liquid level automatic regulating valve group 17 is arranged on the pipeline between the medium-pressure flash tank 6 and the liquid CO2 evaporation heat exchanger 4, and the second DCS liquid level automatic regulating valve group 17 is associated with the liquid level of the medium-pressure flash tank 6, and remote automatic control operation is realized.

[0036] As shown in Figure 1 , the first remote DCS regulating valve 14 is arranged on the pipeline connecting the medium-pressure flash tank 6 and the medium-pressure flash tower 8, and the second remote DCS regulating valve 18 is arranged on the pipeline between the shift gas cooler 7 and the centrifugal CO2 compressor 9; the first remote DCS regulating valve 14 is used for flash gas pressure regulating control, and the second remote DCS regulating valve 18 is used for high-pressure CO2 gas pressure regulating control.

[0037] As shown in Figure 1 , the shift gas washing tower 1 has A, B, C and D four sections, the exhaust end of the A section of the shift gas washing tower 1 is connected with the heat exchange system, and the exhaust end of the B section of the shift gas washing tower 1 is connected with the desulfurized shift gas separation tank 5; the A section of the shift gas washing tower 1 is a shift gas hydrogen sulfide removal section, and the B, C and D sections are shift gas carbon dioxide removal sections.

[0038] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other presenters can develop. It is also possible, however, that only a single element can be present. It is further noted that such a term as "comprising" is intended to mean that the embodiments include the recited elements, but not excluding other elements. "Consisting essentially of when used herein in relation to a composition, means that the composition includes the recited elements, and can include additional elements, so long as the additional elements do not materially alter the basic and novel characteristics of the claimed composition. "Consisting of" when used herein in relation to a composition, means that the composition includes the recited elements, and no additional elements.

[0039] The preferred embodiments of the application disclosed above are only to help explain the principles of the present application. The preferred embodiments do not describe all the details of the present application, nor limit the present application to only the specific embodiments described. It is apparent that many modifications and variations can be made to the present application based on the content of the present disclosure. The present disclosure selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A system for producing high-pressure CO2 gas by low-temperature methanol washing, characterized in that, The system includes a shift gas scrubbing tower (1), a liquid CO2 evaporation heat exchanger (4), a desulfurization shift gas separator (5), a medium-pressure flash tank (6), and a shift gas cooler (7). The exhaust end of the shift gas scrubbing tower (1) is connected to the inlet end of the liquid CO2 evaporation heat exchanger (4) after being cooled by the heat exchange system. The liquid discharge end of the liquid CO2 evaporation heat exchanger (4) is connected to the desulfurization shift gas separator (5). The liquid discharge end of the desulfurization shift gas separator (5) is connected to the inlet end of the medium-pressure flash tank (6). The exhaust end of the medium-pressure flash tank (6) is connected to the inlet end of the medium-pressure flash tower (8). The liquid discharge end of the medium-pressure flash tank (6) is connected to the inlet end of the liquid CO2 evaporation heat exchanger (4). The exhaust end of the liquid CO2 evaporation heat exchanger (4) is connected to the inlet end of the centrifugal CO2 compressor (9) after being heated by the shift gas cooler (7).

2. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: The heat exchange system includes a desulfurization shift gas cooler (2) and a desulfurization shift gas ammonia cooler (3). The exhaust end of the shift gas scrubbing tower (1) is connected to the desulfurization shift gas cooler (2) and the desulfurization shift gas ammonia cooler (3) respectively through pipelines. The exhaust ends of the desulfurization shift gas cooler (2) and the desulfurization shift gas ammonia cooler (3) are both connected to the inlet end of the liquid CO2 evaporation heat exchanger (4).

3. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: The exhaust end of the desulfurization shift gas separator (5) is connected to the inlet end of the shift gas scrubbing tower (1) via a return gas pipeline (10).

4. The method for preparing high pressure using low-temperature methanol washing according to claim 2, characterized in that: The pipeline includes an outlet pipeline (11), and the outlet pipeline (11) is connected to a first gas pipe (111) and a second gas pipe (112). The first gas pipe (111) is connected to the inlet of the desulfurization conversion gas cooler (2), and the second gas pipe (112) is connected to the inlet of the desulfurization conversion gas ammonia cooler (3).

5. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: A first remote DCS regulating valve (14) is installed on the pipeline connecting the medium-pressure flash tank (6) and the medium-pressure flash tower (8).

6. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: The desulfurization shift gas separator (5) and the medium-pressure flash tank (6) are equipped with SIS control valves (15).

7. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: The desulfurization shift gas separator (5) and the medium-pressure flash tank (6) are equipped with a first DCS automatic level regulating valve group (16), which is associated with the level of the desulfurization shift gas separator (5) to realize remote automatic control operation.

8. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: The medium-pressure flash tank (6) and the liquid CO2 evaporation heat exchanger (4) are equipped with a second DCS automatic level regulating valve group (17), which is associated with the liquid level of the medium-pressure flash tank (6) to realize remote automatic control operation.

9. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: A second remote DCS regulating valve (18) is provided on the pipeline between the gas converter (7) and the centrifugal CO2 compressor (9).

10. The low-temperature methanol washing system for producing high-pressure CO2 gas according to claim 1, characterized in that: The shift gas scrubbing tower (1) has four sections: A, B, C, and D. The exhaust end of section A of the shift gas scrubbing tower (1) is connected to the heat exchange system, and the inlet end of section B of the shift gas scrubbing tower (1) is connected to the exhaust end of the desulfurization shift gas separator (5).

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