Device for separating LNG (liquefied natural gas) and CO (carbon monoxide) through dual-circulation refrigeration and cryogenic separation of mixed refrigerant and nitrogen

Abstract

The utility model discloses a device for separating LNG (Liquefied Natural Gas) and CO (Carbonic Oxide) through dual-circulation refrigeration and cryogenic separation of mixed refrigerants and nitrogen. Comprising a main heat exchanger, a heavy hydrocarbon separator, an MRC low-temperature separator, a low-temperature separator, a hydrogen stripping tower, a hydrogen stripping tower reboiler, an LNG separation tower, an LNG separation tower reboiler, an LNG separation tower return tank, an LNG separation tower condenser, an N2 / CO separation tower, an N2 / CO separation tower reboiler, an N2 / CO separation tower return tank, an N2 / CO separation tower condenser, a mixed refrigerant compressor system and a nitrogen compression system. In addition, due to the fact that a low-temperature separator, a hydrogen stripping tower, an LNG separation tower and an N2 / CO separation tower are arranged in the process, the purity of CO is larger than 98.5% mol, and cold energy is provided for condensation and liquefaction of raw material gas and nitrogen and liquefaction and supercooling of LNG through a mixed refrigerant refrigeration cycle.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature deep-cold liquefaction separation, in particular to a device for deep-cold separation of LNG and CO by dual-circulation refrigeration of mixed refrigerant and nitrogen. Background Art

[0002] Synthesis gas is a mixture of carbon monoxide and hydrogen in a certain volume ratio. It is an important chemical raw material. Through synthesis reactions, some important chemical products can be obtained, such as methanol, formic acid, ethanol, acetic acid, acetic anhydride, ethylene glycol, etc.

[0003] The raw materials of syngas are very wide. It can be produced by gasification of solid fuels such as coal or coke, or produced by natural gas and light hydrocarbons such as ethylene, or produced by oxidation of heavy oil. With the adjustment of energy structure and low-carbon drive, many organic chemical products have changed from dependence on oil to coal, which can realize the rational utilization of "waste gas" such as CH4, CO, CO2 in some existing industries, especially in the utilization of coal, truly realize high added value and a high degree of unity of resources, energy and environmental protection, and promote the sustainable development of chemical industry.

[0004] Under high temperature conditions, oxygen and water are used as gasifiers to generate coal gas, the main components of which are hydrogen, methane, CO, CO2, nitrogen, etc. Using coal gas to produce LNG and co-produce ethanol, acetic acid, ethylene glycol, etc. not only reduces the waste of resources and environmental pollution, but also brings very good economic benefits to the factory.

[0005] The utility model provides a device and method for low-temperature deep-cold separation of LNG and co-production of CO and rich hydrogen. A cold box can produce LNG while co-producing CO with a purity of more than 98.5% mol and more than 85% mol of rich hydrogen. The utility model also has the advantages of short process flow, high utilization rate of raw gas, high yield of hydrogen and CO, low energy consumption, reasonable investment, etc. Utility Model Content

[0006] In order to overcome the shortcomings of the prior art, the utility model provides a device for deep-cold separation of LNG and CO by dual-circulation refrigeration of mixed refrigerant and nitrogen with simple process, flexible adjustment, reliable operation, easy operation and low energy consumption.

[0007] A device for deep-cold separation of LNG and CO by dual-circulation refrigeration of mixed refrigerant and nitrogen includes a main heat exchanger, a heavy hydrocarbon separator, an MRC low-temperature separator, a low-temperature separator, a hydrogen stripping tower, a hydrogen stripping tower reboiler, an LNG separation tower, an LNG separation tower reboiler, an LNG separation tower reflux tank, an LNG separation tower condenser, an N2 / CO separation tower, an N2 / CO separation tower reboiler, an N2 / CO separation tower reflux tank, an N2 / CO separation tower condenser, a mixed refrigerant compressor system, and a nitrogen compression system. The main heat exchanger is provided with a CO channel I, a raw gas channel I, a high-pressure hydrogen channel, a medium-pressure hydrogen channel, a nitrogen-rich channel I, a high-pressure nitrogen channel I, a reflux low-pressure nitrogen channel I, a high-pressure gas-phase refrigerant channel I, a reflux refrigerant channel, a high-pressure liquid-phase refrigerant channel I, a raw gas channel II, a high-pressure gas-phase refrigerant channel II, a high-pressure liquid-phase refrigerant channel II, an LNG channel, a high-pressure nitrogen channel II, a methane-rich channel I and a methane-rich channel II. The LNG separation tower condenser is provided with a carbon monoxide-rich channel I and a reflux low-pressure nitrogen channel II. The CO / CH4 separation tower condenser is provided with a reflux low-pressure nitrogen channel II. The inlet of the raw gas channel I is connected to the purified raw gas pipeline outside, the outlet of the raw gas channel I is connected to the feed port of the heavy hydrocarbon separator, the bottom liquid phase outlet of the heavy hydrocarbon separator is connected to the external heavy hydrocarbon storage unit, the top gas phase outlet of the heavy hydrocarbon separator is connected to the inlet of the raw gas channel II, the raw gas channel II is connected to the feed port of the low-temperature separator, the top gas phase outlet of the low-temperature separator is connected to the inlet of the high-pressure hydrogen channel, the outlet of the high-pressure hydrogen channel is connected to the hydrogen-rich pipeline outside the boundary, and the bottom liquid phase outlet pipe of the low-temperature separator is connected to the feed port of the low-temperature separator. The line is divided into a methane-rich pipeline I and a methane-rich pipeline II, the inlet of the methane-rich channel II is connected to the methane-rich pipeline I, the outlet of the methane-rich channel II is connected to the feed port of the hydrogen stripping tower, the methane-rich pipeline II is connected to the feed port of the hydrogen stripping tower, the gas phase outlet at the top of the hydrogen stripping tower is connected to the inlet of the medium-pressure hydrogen channel, the outlet of the medium-pressure hydrogen channel is connected to the external medium-pressure hydrogen pipeline, the liquid phase outlet pipeline at the bottom of the hydrogen stripping tower is divided into a methane-rich pipeline III and a methane-rich pipeline IV, the inlet of the methane-rich channel I is connected to the methane-rich pipeline III, the outlet of the methane-rich channel I is connected to the feed port of the LNG separation tower The methane-rich pipeline IV is connected to the feed port of the LNG separation tower, the liquid phase outlet at the bottom of the LNG separation tower is connected to the inlet of the LNG channel, the outlet of the LNG channel is connected to the LNG storage and transportation pipeline outside the boundary, the gas phase outlet at the top of the LNG separation tower is connected to the inlet of the carbon monoxide-rich channel I of the LNG separation tower condenser, the outlet of the carbon monoxide-rich channel I is connected to the feed port of the LNG separation tower reflux tank, the liquid phase outlet at the bottom of the LNG separation tower reflux tank is connected to the feed port at the top of the LNG separation tower, and the gas phase outlet at the top of the LNG separation tower reflux tank is connected to the feed port of the N2 / CO separation tower.The gas phase outlet at the top of the N2 / CO separation tower is connected to the inlet of the nitrogen-rich gas channel II, the outlet of the nitrogen-rich gas channel II is connected to the feed port of the reflux tank of the N2 / CO separation tower, the liquid phase outlet at the bottom of the reflux tank of the N2 / CO separation tower is connected to the feed port at the top of the N2 / CO separation tower, the gas phase outlet at the top of the reflux tank of the N2 / CO separation tower is connected to the inlet of the nitrogen-rich gas channel I, the outlet of the nitrogen-rich gas channel I is connected to the nitrogen-rich gas pipeline outside the boundary, the liquid phase outlet at the bottom of the N2 / CO separation tower is connected to the inlet of the CO channel II, and the CO channel I The outlet of I is connected to the inlet of CO channel I, the outlet of CO channel I is connected to the CO pipeline outside the boundary, the high-pressure liquid-phase mixed refrigerant pipeline of the mixed refrigerant compressor system is connected to the inlet of high-pressure liquid-phase refrigerant channel I, the outlet of high-pressure liquid-phase refrigerant channel I is connected to the pipe mouth of the reflux refrigerant channel, the high-pressure gas-phase mixed refrigerant of the mixed refrigerant compressor system is connected to the inlet of high-pressure gas-phase refrigerant channel I, the outlet of high-pressure gas-phase refrigerant channel I is connected to the feed port of MRC low-temperature separator, and the liquid phase outlet at the bottom of MRC low-temperature separator is connected to the high-pressure liquid-phase refrigerant channel The inlet of the high-pressure liquid-phase refrigerant channel II is connected, the outlet of the high-pressure liquid-phase refrigerant channel II is connected to the inlet of the LNG separation tower reboiler, the outlet of the LNG separation tower reboiler is connected to the pipe mouth of the reflux refrigerant channel, the gas phase outlet at the top of the MRC low-temperature separator is connected to the inlet of the high-pressure gas-phase refrigerant channel II, the outlet of the high-pressure gas-phase refrigerant channel II is connected to the inlet of the hydrogen stripping tower reboiler, the outlet of the hydrogen stripping tower reboiler is connected to the pipe mouth of the reflux refrigerant channel, and the outlet of the reflux refrigerant channel is connected to the inlet of the mixed refrigerant compressor system; the nitrogen compression system The outlet of the system is connected to the inlet of the high-pressure nitrogen channel I, the outlet of the high-pressure nitrogen channel I is connected to the inlet of the N2 / CO separation tower reboiler, the outlet of the N2 / CO separation tower reboiler is connected to the inlet of the high-pressure nitrogen channel II, the outlet of the high-pressure nitrogen channel II is connected to the reflux low-pressure nitrogen channel II and the reflux low-pressure nitrogen channel III respectively, the outlet of the reflux low-pressure nitrogen channel II and the outlet of the reflux low-pressure nitrogen channel III are both connected to the inlet of the reflux low-pressure nitrogen channel I, and the outlet of the reflux low-pressure nitrogen channel I is connected to the inlet of the nitrogen compression system.

[0008] Preferably, the hydrogen stripping tower, LNG separation tower and N2 / CO separation tower are packed towers or plate towers.

[0009] Preferably, a regulating valve a is provided on the pipeline at the pipe inlet of the return refrigerant channel, a regulating valve b is provided on the pipeline at the pipe inlet of the return refrigerant channel, and a regulating valve c is provided on the pipeline at the pipe inlet of the return refrigerant channel.

[0010] Preferably, a regulating valve d is provided at the bottom liquid phase outlet pipeline of the heavy hydrocarbon separator for controlling the liquid level of the heavy hydrocarbon separator.

[0011] Preferably, the LNG channel outlet pipeline is provided with a regulating valve e for controlling the liquid level of the LNG separation tower.

[0012] Preferably, the low-temperature separator gas phase outlet pipeline is provided with a regulating valve f for controlling the liquid level of the heavy hydrocarbon separator.

[0013] Preferably, the methane-enriched pipeline I of the liquid phase outlet pipeline at the bottom of the low-temperature separator is provided with a regulating valve g for controlling the flow rate of the liquid methane-enriched channel II at the bottom of the low-temperature separator.

[0014] Preferably, a regulating valve h is provided on the methane-rich pipeline II of the bottom liquid phase outlet pipeline of the low-temperature separator to control the liquid level of the low-temperature separator.

[0015] Preferably, a regulating valve i is provided between the inlet pipeline and the outlet pipeline of the hydrogen stripping tower reboiler to control the temperature of LNG entering the kettle of the hydrogen stripping tower.

[0016] Preferably, a regulating valve j is provided in the methane-enriched pipeline III of the liquid phase outlet pipeline at the bottom of the hydrogen stripping tower to control the flow rate of the liquid methane-enriched channel I at the bottom of the hydrogen stripping tower.

[0017] Preferably, a regulating valve k is provided on the methane-rich pipeline IV of the bottom liquid phase outlet pipeline of the hydrogen stripping tower to control the liquid level of the hydrogen stripping tower.

[0018] Preferably, a regulating valve 1 is provided at the inlet pipeline of the reflux low-pressure nitrogen channel II to control the temperature of the carbon monoxide-rich gas exiting the carbon monoxide-rich channel I.

[0019] Preferably, a regulating valve m is provided on the gas phase outlet pipeline at the top of the reflux tank of the LNG separation tower to control the pressure of the LNG separation tower.

[0020] Preferably, a regulating valve n is provided between the inlet pipeline and the outlet pipeline of the LNG separation tower reboiler to control the temperature of the kettle of the LNG separation tower.

[0021] Preferably, a regulating valve o is provided on the gas phase outlet pipeline at the top of the reflux tank of the N2 / CO separation tower to control the pressure of the N2 / CO separation tower.

[0022] Preferably, a regulating valve p is provided at the inlet pipeline of the reflux low-pressure nitrogen channel III to control the temperature of the nitrogen-rich gas exiting the nitrogen-rich channel II.

[0023] Preferably, a regulating valve q is provided at the bottom liquid phase outlet pipeline of the N2 / CO separation tower to control the liquid level of the N2 / CO separation tower.

[0024] Preferably, a regulating valve r is provided between the inlet pipeline and the outlet pipeline of the N2 / CO separation tower reboiler to control the temperature of the N2 / CO separation tower kettle.

[0025] Preferably, a regulating valve s is provided between the inlet and outlet pipelines of the reflux low-pressure nitrogen channel III.

[0026] Preferably, a regulating valve t is provided on the gas phase outlet pipeline at the top of the hydrogen stripping tower to control the pressure of the hydrogen stripping tower.

[0027] Preferably, the hydrogen stripping tower reboiler, the LNG separation tower reboiler and the N2 / CO separation tower reboiler can be internal or external.

[0028] A method for cryogenic separation of LNG and CO by dual-cycle refrigeration of mixed refrigerant and nitrogen, characterized in that it comprises the following steps:

[0029] S1. The purified raw gas containing hydrogen, carbon monoxide, methane, ethane, propane and nitrogen enters the raw gas channel I, is cooled to -60°C by the reflux cold flow, and is partially condensed, and then enters the heavy hydrocarbon separator for heavy hydrocarbon separation. Heavy hydrocarbons are obtained at the bottom of the heavy hydrocarbon separator, and are sent to the boundary area for heavy hydrocarbon storage after throttling and pressure reduction by the liquid level regulating valve d; the gas phase at the top of the heavy hydrocarbon separator enters the raw gas channel II again and is cooled to -180°C, and enters the low-temperature separator for gas-liquid separation. The liquid at the bottom is divided into two parts. One part is regulated by the flow regulating valve g, and then enters the methane-rich channel II for reheating. After reheating to -163°C, it enters the bottom of the hydrogen stripping tower for distillation, and the other part is decompressed by the liquid level regulating valve h and then enters the top of the hydrogen stripping tower for distillation.

[0030] S2. A hydrogen stripping tower reboiler is provided at the bottom of the hydrogen stripping tower, which is used as a heat source for heat exchange with the high-pressure gas phase refrigerant after heat exchange, temperature reduction and separation. In the hydrogen stripping tower, the rising gas and the downstream liquid transfer heat and mass on the surface of the structured packing. The hydrogen content of the gas gradually increases during the rising process. Medium-pressure rich hydrogen is obtained at the top of the hydrogen stripping tower. After being reheated to room temperature through the medium-pressure hydrogen channel through the pressure regulating valve t, it is discharged from the de-boundary area of ​​the main heat exchanger of the cold box. The liquid at the bottom of the hydrogen stripping tower is divided into two parts. One part is regulated by the flow regulating valve j, enters the methane-rich channel I for reheating, and enters the lower part of the LNG separation tower. The other part is decompressed through the liquid level regulating valve k and enters the middle part of the LNG separation tower to participate in distillation.

[0031] S3. An LNG separation tower condenser is provided at the top of the LNG separation tower, and throttled liquid nitrogen is used as a cold source; an LNG separation tower reboiler is provided at the bottom of the LNG separation tower, and the high-pressure liquid phase refrigerant after heat exchange, temperature reduction and separation is used as a heat source to make LNG evaporate as rising gas, and the rising gas and the reflux liquid transfer heat and mass on the surface of the structured packing, so that the CO content in the LNG obtained in the LNG separation tower kettle is less than 0.5%, and the LNG is sent to the LNG channel to be supercooled to -162°C, and is sent to the boundary LNG storage tank after throttling and pressure reduction by the liquid level regulating valve e; in the process of rising gas in the LNG separation tower, the nitrogen and CO contents gradually increase, and the methane content gradually decreases, and CO-rich gas is obtained at the top of the LNG separation tower, enters the carbon monoxide-rich channel I and exchanges heat with the liquid nitrogen after throttling and pressure reduction by the regulating valve l, and the liquid nitrogen evaporates, and part of the CO-rich gas is liquefied and separated in the LNG separation tower reflux tank, and the separated liquid phase is used as the reflux liquid of the LNG separation tower, and the uncondensed CO-rich gas passes through the pressure regulating valve m and enters the middle part of the N2 / CO separation tower for distillation.

[0032] S4. A N2 / CO separation tower condenser is provided at the top of the N2 / CO separation tower, and the liquid nitrogen after pressure reduction and throttling and the liquid product CO in the bottom of the tower are used as cold sources; a N2 / CO separation tower reboiler is provided at the bottom of the N2 / CO separation tower, and the nitrogen in the liquid CO in the bottom of the tower is evaporated with the high-pressure nitrogen after heat exchange and temperature reduction as the rising gas. In the N2 / CO separation tower, the rising gas and the reflux liquid transfer heat and mass on the surface of the structured packing. The nitrogen content of the gas gradually increases and the CO content gradually decreases during the rising process. Nitrogen-rich gas is obtained at the top of the N2 / CO separation tower and enters the nitrogen-rich gas channel II and The liquid nitrogen after throttling and depressurization by regulating valve p is exchanged with the liquid product CO after throttling and depressurization by regulating valve q. Part of the CO is liquefied and separated in the reflux tank of the N2 / CO separation tower. The separated liquid phase is used as the reflux liquid of the N2 / CO separation tower. The uncondensed nitrogen-rich gas passes through the pressure regulating valve o and returns to the nitrogen-rich gas channel I for reheating to the room temperature and exiting the cold box delimiting area. Liquid CO is distilled at the bottom of the N2 / CO separation tower to obtain liquid CO. After throttling and depressurization by the liquid level regulating valve q, it is sent to CO channel II as a part of the cold source of the N2 / CO separation tower condenser, and then enters CO channel I for reheating to the room temperature and exiting the cold box delimiting area.

[0033] S5. The condensation and liquefaction of the raw gas and nitrogen, as well as the liquefaction and subcooling of LNG are provided by the mixed refrigerant refrigeration cycle. First, the high-pressure liquid refrigerant from the mixed refrigerant compressor system is subcooled to -30 to -70°C in the high-pressure liquid refrigerant channel I of the main heat exchanger, and enters the pipe mouth of the reflux refrigerant channel after throttling and reducing the pressure through the regulating valve a. The high-pressure gas refrigerant of the mixed refrigerant compressor system is cooled to -30 to -70°C in the high-pressure gas refrigerant channel I of the main heat exchanger, and then enters the MRC low-temperature separator for gas-liquid separation. The liquid separated at the bottom enters the high-pressure liquid refrigerant channel II and is subcooled to -130 to -80°C, and then enters the LNG separation tower reboiler to provide a heat source for the LNG separation tower kettle, and control the CO content of LNG in the LNG separation tower kettle to be lower than 0.5%. The low-temperature liquid in the tower kettle is cooled to -145~-100℃, and enters the pipe mouth of the reflux refrigerant channel after throttling and reducing the pressure through the regulating valve b; the high-pressure gas phase refrigerant from the top of the MRC low-temperature separator enters the high-pressure gas phase refrigerant channel II to be cooled and condensed to about -150℃, and then enters the hydrogen stripping tower reboiler to provide a heat source for the hydrogen stripping tower kettle, and control the hydrogen content of the methane-rich liquid in the hydrogen stripping tower kettle to be lower than 0.001%, and control the pipe mouth of the reflux refrigerant channel after throttling and reducing the pressure through the regulating valve c. The mixed refrigerant entering the reflux refrigerant channel absorbs heat and evaporates, all evaporates into gas and is reheated to room temperature before exiting the main heat exchanger, and then returns to the mixed refrigerant compressor system to complete the mixed refrigerant refrigeration cycle.

[0034] S6. The cryogenic separation of the feed gas is provided by the nitrogen cycle. First, the high-pressure nitrogen from the nitrogen compression system is cooled to -145~-150℃ in the high-pressure nitrogen channel I, and then enters the N2 / CO separation tower reboiler and is cooled by the liquid in the N2 / CO separation tower kettle. It is then sent to the main heat exchanger high-pressure nitrogen channel II to be condensed and supercooled. The nitrogen becomes liquid nitrogen and is then divided into three parts. One part of the liquid nitrogen enters the reflux low-pressure nitrogen channel II after throttling and reducing the pressure through the temperature regulating valve l, and controls the temperature of the CO-rich gas entering the LNG separation tower reflux tank to be between -178~-170℃, which is the top of the LNG separation tower. The other part of the liquid nitrogen enters the reflux low-pressure nitrogen channel III after throttling and reducing the pressure through the temperature regulating valve p, and controls the temperature of the rich nitrogen entering the reflux tank of the N2 / CO separation tower to be between -182 and -175°C, providing a cold source for the separation of carbon monoxide and CO at the top of the N2 / CO separation tower; the last part of the liquid nitrogen enters the reflux low-pressure nitrogen channel I after throttling and reducing the pressure through the regulating valve s, and merges with the liquid nitrogen refluxed from the reflux low-pressure nitrogen channel II and the reflux low-pressure nitrogen channel III, and then enters the reflux low-pressure nitrogen channel I, is restored to room temperature, and then exits the main heat exchanger, and then returns to the inlet of the nitrogen compression system to complete the nitrogen refrigeration cycle.

[0035] Preferably, the mixed refrigerant includes one or more combinations of nitrogen, methane, ethane, ethylene, propane, propylene, butane and isopentane.

[0036] Preferably, the pressure at the outlet of the mixed refrigerant compressor unit may range from 2.0 to 6.0 MPaG.

[0037] Preferably, the outlet pressure of the nitrogen compressor may range from 1.5 to 3.0 MPaG.

[0038] The utility model has the following advantages:

[0039] 1. High hydrogen yield: -180℃ low temperature separation is adopted, the purity of hydrogen-rich gas can reach 85% mol. In addition, a hydrogen stripping tower is set up to recycle the hydrogen in the methane-rich gas, so that the yield of hydrogen (high-pressure hydrogen-rich gas and medium-pressure hydrogen-rich gas) is greater than 98%.

[0040] 2. High purity of CO: Due to the installation of low-temperature separator, hydrogen stripping tower, LNG separation tower and N2 / CO separation tower in the process, the purity of CO is greater than 98.5% mol.

[0041] 3. Low energy consumption: The condensation and liquefaction of raw gas and nitrogen, as well as the liquefaction and supercooling of LNG are provided by the mixed refrigerant refrigeration cycle, that is, the MRC (mixed refrigerant refrigeration cycle) provides a temperature range of -162°C for the pre-cooling of raw gas and the supercooling of LNG. The cryogenic separation of raw gas is provided by the nitrogen cycle, that is, a cold source in the temperature range of -182 to -162°C, which realizes the provision of different temperature ranges and different cooling capacities, greatly reducing the energy consumption of the cryogenic separation device.

[0042] 4. In addition, the device has the advantages of easy maintenance, reliable operation, safety and reliability, and wide practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the structure of a device for cryogenic separation of LNG and CO using a dual-cycle refrigeration system of mixed refrigerant and nitrogen;

[0044] In the figure: 1-main heat exchanger, 2-heavy hydrocarbon separator, 3-MRC low-temperature separator, 4-low-temperature separator, 5-hydrogen stripping tower, 6-hydrogen stripping tower reboiler, 7-LNG separation tower, 8-LNG separation tower reboiler, 9-LNG separation tower reflux tank, 10-LNG separation tower condenser, 11-N2 / CO separation tower, 12-N2 / CO separation tower reboiler, 13-N2 / CO separation tower reflux tank, 14-N2 / CO separation tower condenser, 15-mixed refrigerant compressor system, 16-nitrogen compression system. A1-CO channel I, A2-raw gas channel I, A3-high-pressure hydrogen channel, A4-medium-pressure hydrogen channel, A5-nitrogen-rich channel I, A6-high-pressure nitrogen channel I, A7-reflux low-pressure nitrogen channel I, A8-high-pressure gas phase refrigerant channel I, A9-reflux refrigerant channel, A10-high-pressure liquid phase refrigerant channel I, A11-raw gas channel II, A12-high-pressure gas phase refrigerant channel II, A13-high-pressure liquid phase refrigerant channel II, A14-LNG channel, A15-high-pressure nitrogen channel II, A16-methane-rich channel I and A17-methane-rich channel II, B1-carbon monoxide-rich channel I and B2-reflux low-pressure nitrogen channel II, C1-reflux low-pressure nitrogen channel III, C2-CO channel II and C3-nitrogen-rich channel II. DETAILED DESCRIPTION

[0045] The following is an explanation of the implementation of the present invention by specific specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this utility model are limited to the implementation. On the contrary, the purpose of introducing the utility model in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present utility model. In order to provide a deep understanding of the present utility model, many specific details will be included in the following description. The present utility model can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present utility model, some specific details will be omitted in the description. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. It should be noted that in this specification, similar reference numerals and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined and explained in the subsequent figures.

[0046] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate quantity restrictions, but indicate the existence of at least one. Words such as "set", "connected", "connected" and similar words 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 indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances. The directions or positional relationships indicated by “upper”, “lower”, “left”, “right”, “inside”, “bottom”, etc. are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the utility model.

[0047] In order to make the purpose, technical solution and advantages of the present invention more clear, the implementation mode of the present invention will be further described in detail below with reference to the accompanying drawings.

[0048] In this embodiment, as shown in the attached Figure 1As shown, the device includes a main heat exchanger 1, a heavy hydrocarbon separator 2, an MRC low-temperature separator 3, a low-temperature separator 4, a hydrogen stripping tower 5, a hydrogen stripping tower reboiler 6, an LNG separation tower 7, an LNG separation tower reboiler 8, an LNG separation tower reflux tank 9, an LNG separation tower condenser 10, an N2 / CO separation tower 11, an N2 / CO separation tower reboiler 12, an N2 / CO separation tower reflux tank 13, an N2 / CO separation tower condenser 14, a mixed refrigerant compressor system 15, and a nitrogen compression system 16. The main heat exchanger 1 is provided with a CO channel IA1, a raw gas channel IA2, a high-pressure hydrogen channel A3, a medium-pressure hydrogen channel A4, a nitrogen-rich channel IA5, a high-pressure nitrogen channel IA6, a reflux low-pressure nitrogen channel IA7, a high-pressure gas-phase refrigerant channel IA8, a reflux refrigerant channel A9, a high-pressure liquid-phase refrigerant channel IA10, a raw gas channel IIA11, a high-pressure gas-phase refrigerant channel IIA12, a high-pressure liquid-phase refrigerant channel IIA13, an LNG channel A14, a high-pressure nitrogen channel IIA15, a methane-rich channel IA16 and a methane-rich channel IIA17, and the LNG separation tower The condenser 10 is provided with a carbon monoxide-rich channel IB1 and a reflux low-pressure nitrogen channel IIB2, the CO / CH4 separation tower condenser is provided with a reflux low-pressure nitrogen channel IIIC1, a CO channel IIC2 and a nitrogen-rich channel IIC3, the inlet of the raw gas channel I A2 is connected to the external purified raw gas pipeline, the outlet of the raw gas channel I A2 is connected to the feed port 2-A of the heavy hydrocarbon separator 2, the bottom liquid phase outlet 2-C of the heavy hydrocarbon separator 2 is connected to the external heavy hydrocarbon storage unit, the top gas phase outlet 2-B of the heavy hydrocarbon separator 2 is connected to the inlet of the raw gas channel IIA11 The raw gas channel IIA11 is connected to the feed port 4-A of the low-temperature separator 4, the gas phase outlet 4-B at the top of the low-temperature separator 4 is connected to the inlet of the high-pressure hydrogen channel A3, the outlet of the high-pressure hydrogen channel A3 is connected to the hydrogen-rich pipeline outside the boundary, the liquid phase outlet pipeline at the bottom of the low-temperature separator 4 is divided into a methane-rich pipeline I201 and a methane-rich pipeline II202, the inlet of the methane-rich channel IIA17 is connected to the methane-rich pipeline I201, the outlet of the methane-rich channel IIA17 is connected to the feed port 5-A of the hydrogen stripping tower 5, and the methane-rich pipeline II202 is connected to the hydrogen stripping tower 5. The tower 5 feed port II5-B is connected, the gas phase outlet 5-D at the top of the hydrogen stripping tower 5 is connected to the inlet of the medium-pressure hydrogen channel A4, the outlet of the medium-pressure hydrogen channel A4 is connected to the external medium-pressure hydrogen pipeline, the pipeline of the liquid phase outlet 5-E at the bottom of the hydrogen stripping tower 5 is divided into a methane-rich pipeline III203 and a methane-rich pipeline IV204, the inlet of the methane-rich channel IA16 is connected to the methane-rich pipeline III203, the outlet of the methane-rich channel IA16 is connected to the feed port 7-A of the LNG separation tower 7, and the methane-rich pipeline IV204 is connected to the feed port II7-B of the LNG separation tower 7,The bottom liquid phase outlet 7-E of the LNG separation tower 7 is connected to the inlet of the LNG channel A14, the outlet of the LNG channel A14 is connected to the off-site LNG storage and transportation pipeline, the top gas phase outlet 7-C of the LNG separation tower 7 is connected to the inlet of the carbon monoxide-rich channel IB1 of the LNG separation tower condenser 10, the outlet of the carbon monoxide-rich channel IB1 is connected to the feed port 9-A of the LNG separation tower reflux tank 9, the bottom liquid phase outlet 9-B of the LNG separation tower reflux tank 9 is connected to the feed port 7-D at the top of the LNG separation tower 7, the top gas phase outlet 9-C of the LNG separation tower reflux tank 9 is connected to the feed port 11-A of the N2 / CO separation tower 11, and the top gas phase outlet 11-B of the N2 / CO separation tower 11 is connected to The inlet of the nitrogen-rich gas channel IIC3 is connected, the outlet of the nitrogen-rich gas channel IIC3 is connected to the feed port 13-A of the N2 / CO separation tower reflux tank 13, the bottom liquid phase outlet 13-B of the N2 / CO separation tower reflux tank 13 is connected to the top feed port 11-C of the N2 / CO separation tower 11, the top gas phase outlet 13-C of the N2 / CO separation tower reflux tank 13 is connected to the inlet of the nitrogen-rich gas channel IA5, the outlet of the nitrogen-rich gas channel IA5 is connected to the nitrogen-rich gas pipeline outside the boundary, the bottom liquid phase outlet 11-D of the N2 / CO separation tower 11 is connected to the inlet of the CO channel IIC2, the outlet of the CO channel IIC2 is connected to the inlet of the CO channel IA1, and the outlet of the CO channel IA1 is connected to the CO pipeline outside the boundary, The high-pressure liquid-phase mixed refrigerant pipeline of the mixed refrigerant compressor system 15 is connected to the inlet of the high-pressure liquid-phase refrigerant channel IA10, and the outlet of the high-pressure liquid-phase refrigerant channel IA10 is connected to the pipe mouth IA9-A of the reflux refrigerant channel A9. The high-pressure gas-phase mixed refrigerant of the mixed refrigerant compressor system 15 is connected to the inlet of the high-pressure gas-phase refrigerant channel IA8, and the outlet of the high-pressure gas-phase refrigerant channel IA8 is connected to the feed port 3-A of the MRC low-temperature separator 3, and the bottom liquid phase outlet 3-B of the MRC low-temperature separator 3 is connected to the inlet of the high-pressure liquid-phase refrigerant channel II channel A13, and the outlet of the high-pressure liquid-phase refrigerant channel II channel A13 is connected to the inlet of the LNG separation tower reboiler 8, and the outlet of the LNG separation tower reboiler 8 is connected to the reflux refrigerant. The outlet of the MRC low-temperature separator 3 is connected to the pipe mouth IIA9-B of the refrigerant channel A9, the gas phase outlet 3-C at the top of the MRC low-temperature separator 3 is connected to the inlet of the high-pressure gas phase refrigerant channel IIA12, the outlet of the high-pressure gas phase refrigerant channel IIA12 is connected to the inlet of the hydrogen stripping tower reboiler 6, the outlet of the hydrogen stripping tower reboiler 6 is connected to the pipe mouth IIIA9-C of the reflux refrigerant channel A9, the outlet of the reflux refrigerant channel A9 is connected to the inlet of the mixed refrigerant compressor system 15; the outlet of the nitrogen compression system 16 is connected to the inlet of the high-pressure nitrogen channel IA6, the outlet of the high-pressure nitrogen channel IA6 is connected to the inlet of the N2 / CO separation tower reboiler 12, the outlet of the N2 / CO separation tower reboiler 12 is connected to the inlet of the high-pressure nitrogen channel IIA15,The outlet of the high-pressure nitrogen channel IIA15 is connected to the reflux low-pressure nitrogen channel IIB2 and the reflux low-pressure nitrogen channel IIIC1 respectively, and the outlet of the reflux low-pressure nitrogen channel IIB2 and the outlet of the reflux low-pressure nitrogen channel IIIC1 are both connected to the inlet of the reflux low-pressure nitrogen channel IA7, and the outlet of the reflux low-pressure nitrogen channel IA7 is connected to the inlet of the nitrogen compression system 14.

[0049] Preferably, the hydrogen stripping tower 5, the LNG separation tower 7 and the N2 / CO separation tower 11 are packed towers or plate towers.

[0050] Preferably, a regulating valve a101 is set on the pipeline at the entrance of the pipe orifice IA9-A of the return refrigerant channel A9, a regulating valve b102 is set on the pipeline at the entrance of the pipe orifice IIA9-B of the return refrigerant channel A9, and a regulating valve c103 is set on the pipeline at the entrance of the pipe orifice IIIA9-C of the return refrigerant channel A9.

[0051] Preferably, a regulating valve d104 is provided on the bottom liquid phase outlet 2-C pipeline of the heavy hydrocarbon separator 2 for controlling the liquid level of the heavy hydrocarbon separator 2.

[0052] Preferably, the outlet pipeline of the LNG channel A14 is provided with a regulating valve e105 for controlling the liquid level of the LNG separation tower 7 .

[0053] Preferably, a regulating valve f106 is provided on the gas phase outlet 4 -B pipeline of the low-temperature separator 4 for controlling the liquid level of the heavy hydrocarbon separator 2 .

[0054] Preferably, the methane-enriched pipeline I201 of the liquid phase outlet pipeline at the bottom of the low-temperature separator 4 is provided with a regulating valve g107 for controlling the flow of the liquid methane-enriched channel IIA17 at the bottom of the low-temperature separator 4 .

[0055] Preferably, the methane-rich pipeline II202 of the bottom liquid phase outlet pipeline of the low-temperature separator 4 is provided with a regulating valve h108 for controlling the liquid level of the low-temperature separator 4 .

[0056] Preferably, a regulating valve i109 is provided between the inlet pipeline and the outlet pipeline of the hydrogen stripping tower reboiler 6 to control the temperature of the kettle of the LNG entering the hydrogen stripping tower 5 .

[0057] Preferably, the methane-enriched pipeline III203 of the liquid phase outlet pipeline at the bottom of the hydrogen stripping tower 5 is provided with a regulating valve j110 for controlling the flow rate of the liquid methane-enriched channel IA16 at the bottom of the hydrogen stripping tower 5 .

[0058] Preferably, a regulating valve k111 is provided on the methane-rich pipeline IV204 of the bottom liquid phase outlet pipeline of the hydrogen stripping tower 5 to control the liquid level of the hydrogen stripping tower 5 .

[0059] Preferably, a regulating valve 1112 is provided at the inlet pipeline of the reflux low-pressure nitrogen channel IIB2 to control the temperature of the carbon monoxide-rich gas exiting the carbon monoxide-rich channel IB1.

[0060] Preferably, a regulating valve m113 is provided at the gas phase outlet 9-C pipeline at the top of the LNG separation tower reflux tank 9 to control the pressure of the LNG separation tower 7.

[0061] Preferably, a regulating valve n114 is provided between the inlet pipeline and the outlet pipeline of the LNG separation tower reboiler 8 to control the bottom temperature of the LNG separation tower 7 .

[0062] Preferably, a regulating valve o115 is provided at the gas phase outlet 13-C pipeline at the top of the N2 / CO separation tower reflux tank 13 to control the pressure of the N2 / CO separation tower 11.

[0063] Preferably, a regulating valve p116 is provided at the inlet pipeline of the reflux low-pressure nitrogen channel IIIC1 to control the temperature of the nitrogen-rich gas exiting the nitrogen-rich channel IIC3.

[0064] Preferably, a regulating valve q117 is provided on the bottom liquid phase outlet 11-D pipeline of the N2 / CO separation tower 11 to control the liquid level of the N2 / CO separation tower 11.

[0065] Preferably, a regulating valve r118 is provided between the inlet pipeline and the outlet pipeline of the N2 / CO separation tower reboiler 12 to control the bottom temperature of the N2 / CO separation tower 11.

[0066] Preferably, a regulating valve s119 is provided between the inlet and outlet pipelines of the reflux low-pressure nitrogen channel IIIC1.

[0067] Preferably, a regulating valve t120 is provided at the gas phase outlet 5-D pipeline at the top of the hydrogen stripping tower 5 to control the pressure of the hydrogen stripping tower 5.

[0068] Preferably, the hydrogen stripping tower reboiler 6, the LNG separation tower reboiler 8 and the N2 / CO separation tower reboiler 12 can be internal or external.

[0069] A method for cryogenic separation of LNG and CO by dual-cycle refrigeration of mixed refrigerant and nitrogen, characterized in that it comprises the following steps:

[0070] S1. The purified raw gas containing hydrogen, carbon monoxide, methane, ethane, propane and nitrogen enters the raw gas channel IA2, is cooled to -60°C by the reflux cold flow, and is partially condensed, and then enters the heavy hydrocarbon separator 2 for heavy hydrocarbon separation. Heavy hydrocarbons are obtained at the bottom of the heavy hydrocarbon separator, and are sent to the boundary area for heavy hydrocarbon storage after throttling and pressure reduction by the liquid level regulating valve d104; the gas phase at the top of the heavy hydrocarbon separator 2 enters the raw gas channel IIA11 again and is cooled to -180°C, and enters the low-temperature separator 4 for gas-liquid separation. The liquid at the bottom is divided into two parts. One part is regulated by the flow regulating valve g107, and then enters the methane-rich channel IIA17 for reheating. After reheating to -163°C, it enters the bottom of the hydrogen stripping tower 5 for distillation, and the other part is decompressed by the liquid level regulating valve h108 and enters the top of the hydrogen stripping tower 5 for distillation.

[0071] S2. A hydrogen stripping tower reboiler 6 is provided at the bottom of the hydrogen stripping tower 5, which exchanges heat with the high-pressure gas phase refrigerant after heat exchange, temperature reduction and separation as a heat source. In the hydrogen stripping tower 5, the rising gas and the downstream liquid transfer heat and mass on the surface of the structured packing. The hydrogen content of the gas gradually increases during the rising process. Medium-pressure rich hydrogen is obtained at the top of the hydrogen stripping tower 5. It is reheated to room temperature through the medium-pressure hydrogen channel A4 through the pressure regulating valve t120 and then discharged from the cold box main heat exchanger 1 to the boundary area. The liquid at the bottom of the hydrogen stripping tower 5 is divided into two parts. One part is regulated by the flow regulating valve j110, enters the methane-rich channel IA16 for reheating, and enters the lower part of the LNG separation tower 7. The other part is decompressed by the liquid level regulating valve k111 and enters the middle part of the LNG separation tower 7 to participate in distillation.

[0072] S3, LNG separation tower 7 is provided with LNG separation tower condenser 10 at the top, using throttled liquid nitrogen as cold source; LNG separation tower reboiler 8 is provided at the bottom of LNG separation tower 7, and high-pressure liquid phase refrigerant after heat exchange and temperature reduction separation is used as heat source to make LNG evaporate as rising gas, and the rising gas and reflux liquid transfer heat and mass on the surface of structured packing, so that the CO content in LNG obtained in the kettle of LNG separation tower 7 is less than 0.5%, and LNG is sent to LNG channel A14 to be supercooled to -162℃, and throttled and depressurized by liquid level regulating valve e105. It is then sent to the boundary LNG storage tank; in the process of rising in the LNG separation tower 7, the nitrogen and CO contents gradually increase, and the methane content gradually decreases, and CO-rich gas is obtained at the top of the LNG separation tower 7, and enters the carbon monoxide-rich channel IB1 to exchange heat with the liquid nitrogen that has been throttled and reduced in pressure by the regulating valve l112. The liquid nitrogen evaporates, and part of the CO-rich gas is liquefied and separated in the LNG separation tower reflux tank 9. The separated liquid phase is used as the reflux liquid of the LNG separation tower 7, and the uncondensed CO-rich gas passes through the pressure regulating valve m113 and enters the middle part of the N2 / CO separation tower 11 for distillation.

[0073] S4, N2 / CO separation tower 11 is provided with N2 / CO separation tower condenser 14 at the top, using the liquid nitrogen after pressure reduction and throttling and the liquid product CO in the bottom of the tower as cold sources; N2 / CO separation tower 11 is provided with N2 / CO separation tower reboiler 12 at the bottom, and the nitrogen in the liquid CO in the bottom of the tower is evaporated with the high-pressure nitrogen after heat exchange and temperature reduction as the rising gas. In the N2 / CO separation tower 11, the rising gas and the reflux liquid transfer heat and mass on the surface of the structured packing. The nitrogen content of the gas gradually increases and the CO content gradually decreases during the rising process. Nitrogen-rich gas is obtained at the top of the N2 / CO separation tower 11, enters the nitrogen-rich gas channel IIC3 and passes through the regulating valve p The liquid nitrogen after throttling and depressurization by 116 is exchanged with the liquid product CO after throttling and depressurization by regulating valve q117, and part of the CO is liquefied and separated in the reflux tank 13 of the N2 / CO separation tower. The separated liquid phase is used as the reflux liquid of the N2 / CO separation tower 11, and the uncondensed nitrogen-rich gas passes through the pressure regulating valve o115, returns to the nitrogen-rich gas channel IA5 for reheating to room temperature and exiting the cold box de-boundary area, and is distilled at the bottom of the N2 / CO separation tower 11 to obtain liquid CO. After throttling and depressurization by the liquid level regulating valve q117, it is sent to the CO channel IIC2 as a part of the cold source of the N2 / CO separation tower condenser 14, and then enters the CO channel IA1 for reheating to room temperature and exiting the cold box de-boundary area.

[0074] S5. The condensation and liquefaction of the raw gas and nitrogen, as well as the liquefaction and subcooling of LNG are provided by the mixed refrigerant refrigeration cycle. First, the high-pressure liquid refrigerant from the mixed refrigerant compressor system 15 is subcooled to -30 to -70°C in the high-pressure liquid refrigerant channel IA10 of the main heat exchanger 1, and enters the pipe mouth A9-A of the reflux refrigerant channel A9 after throttling and reducing the pressure through the regulating valve a101. The high-pressure gas-phase refrigerant of the mixed refrigerant compressor system 15 is cooled to -30 to -70°C in the high-pressure gas-phase refrigerant channel IA8 of the main heat exchanger 1, and then enters the MRC low-temperature separator 3 for gas-liquid separation. The liquid separated at the bottom enters the high-pressure liquid-phase refrigerant channel IIA13 and is subcooled to -130 to -80°C, and then enters the LNG separation tower reboiler 8 to provide a heat source for the LNG separation tower 7 kettle, and control the CO content of the LNG in the LNG separation tower 7 kettle to be lower than 0.5%. The low-temperature liquid in the kettle is cooled to -145~-100℃, and enters the pipe mouth A9-B of the reflux refrigerant channel A9 after throttling and reducing the pressure through the regulating valve b102; the high-pressure gas-phase refrigerant from the top of the MRC low-temperature separator 3 enters the high-pressure gas-phase refrigerant channel IIA12 to be cooled and condensed to about -150℃, and then enters the hydrogen stripping tower reboiler 6 to provide a heat source for the kettle of the hydrogen stripping tower 5, and control the hydrogen content of the methane-rich liquid in the kettle of the hydrogen stripping tower 5 to be lower than 0.1%, and control the mixed refrigerant entering the pipe mouth IIIA9-C of the reflux refrigerant channel A9 after throttling and reducing the pressure through the regulating valve c103. The mixed refrigerant entering the reflux refrigerant channel A9 absorbs heat and evaporates, all evaporates into gas and is reheated to room temperature before exiting the main heat exchanger 1, and then returns to the mixed refrigerant compressor system 15 to complete the mixed refrigerant refrigeration cycle.

[0075] S6. The cryogenic separation of the raw gas is provided by the nitrogen cycle. First, the high-pressure nitrogen from the nitrogen compression system 14 is cooled to -145--150°C in the high-pressure nitrogen channel IA6, and then enters the N2 / CO separation tower reboiler 12 to be cooled by the liquid in the bottom of the N2 / CO separation tower 11, and then is sent to the high-pressure nitrogen channel IIA15 of the main heat exchanger 1 to be condensed and supercooled. The nitrogen becomes liquid nitrogen and is then divided into three parts. One part of the liquid nitrogen enters the reflux low-pressure nitrogen channel IIB2 after throttling and reducing the pressure through the temperature regulating valve l112, and controls the temperature of the CO-rich gas entering the LNG separation tower reflux tank 9 to be between -178 and -170°C, which is the top of the LNG separation tower 7. The separation of carbon monoxide and methane provides a cold source; another part of the liquid nitrogen enters the reflux low-pressure nitrogen channel IIIC1 after throttling and reducing the pressure through the temperature regulating valve p116, and controls the temperature of the rich nitrogen entering the N2 / CO separation tower reflux tank 13 to be between -182 and -175°C, providing a cold source for the separation of carbon monoxide and CO at the top of the N2 / CO separation tower 11; the last part of the liquid nitrogen is throttled and reduced in pressure through the regulating valve s119, and then merges with the liquid nitrogen refluxed from the reflux low-pressure nitrogen channel IIB2 and the reflux low-pressure nitrogen channel IIIC1, enters the reflux low-pressure nitrogen channel IA7, is restored to room temperature, and then exits the main heat exchanger 1, and then returns to the inlet of the nitrogen compression system 16 to complete the nitrogen refrigeration cycle.

[0076] This embodiment can be implemented according to the parameters of the purified raw gas in the following table, and the parameters and components of the obtained high-pressure hydrogen-rich gas, medium-pressure hydrogen-rich gas, CO gas, nitrogen-rich gas and LNG are shown in Table 1 below:

[0077] Table 1 Parameters and components of Example 1

[0078]

[0079]

[0080] Among them: the molar yield of methane is 97.3%, and the molar yield of hydrogen is 99.9%.

[0081] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A device for cryogenic separation of LNG and CO by dual-circulation refrigeration of mixed refrigerant and nitrogen, characterized in that: The invention comprises a main heat exchanger (1), a heavy hydrocarbon separator (2), an MRC low-temperature separator (3), a low-temperature separator (4), a hydrogen stripping tower (5), a hydrogen stripping tower reboiler (6), an LNG separation tower (7), an LNG separation tower reboiler (8), an LNG separation tower reflux tank (9), an LNG separation tower condenser (10), an N2 / CO separation tower (11), an N2 / CO separation tower reboiler (12), an N2 / CO separation tower reflux tank (13), an N2 / CO separation tower condenser (14), a mixed refrigerant compressor system (15), and a nitrogen compression system (16). The main heat exchanger (1) is provided with a CO channel I (A1) and a raw gas channel I (A2). , a high-pressure hydrogen channel (A3), a medium-pressure hydrogen channel (A4), a nitrogen-rich channel I (A5), a high-pressure nitrogen channel I (A6), a reflux low-pressure nitrogen channel I (A7), a high-pressure gas-phase refrigerant channel I (A8), a reflux refrigerant channel (A9), a high-pressure liquid-phase refrigerant channel I (A10), a feed gas channel II (A11), a high-pressure gas-phase refrigerant channel II (A12), a high-pressure liquid-phase refrigerant channel II (A13), an LNG channel (A14), a high-pressure nitrogen channel II (A15), a methane-rich channel I (A16) and a methane-rich channel II (A17), wherein the LNG separation tower condenser (10) is provided with a carbon monoxide-rich channel I (B1) and a reflux low-pressure nitrogen channel I (A7), a high-pressure gas-phase refrigerant channel I (A8), a reflux refrigerant channel (A9), a high-pressure liquid-phase refrigerant channel I (A10), a feed gas channel II (A11), a high-pressure gas-phase refrigerant channel II (A12), a high-pressure liquid-phase refrigerant channel II (A13), an LNG channel (A14), a high-pressure nitrogen channel II (A15), a methane-rich channel I (A16) and a methane-rich channel II (A17). A reflux low-pressure nitrogen channel II (B2) is provided in the condenser of the CO / CH4 separation tower, a reflux low-pressure nitrogen channel III (C1), a CO channel II (C2) and a nitrogen-rich channel II (C3), the inlet of the raw gas channel I (A2) is connected to the external purified raw gas pipeline, the outlet of the raw gas channel I (A2) is connected to the feed port (2-A) of the heavy hydrocarbon separator (2), the bottom liquid phase outlet (2-C) of the heavy hydrocarbon separator (2) is connected to the external heavy hydrocarbon storage unit, the top gas phase outlet (2-B) of the heavy hydrocarbon separator (2) is connected to the inlet of the raw gas channel II (A11), and the raw gas channel II (A11) is connected to the low-temperature separator (2). The low-temperature separator (4) is connected to the feed port (4-A) of the separator (4), the gas phase outlet (4-B) at the top of the low-temperature separator (4) is connected to the inlet of the high-pressure hydrogen channel (A3), the outlet of the high-pressure hydrogen channel (A3) is connected to the hydrogen-rich pipeline outside the boundary, the liquid phase outlet pipeline at the bottom of the low-temperature separator (4) is divided into a methane-rich pipeline I (201) and a methane-rich pipeline II (202), the inlet of the methane-rich channel II (A17) is connected to the methane-rich pipeline I (201), the outlet of the methane-rich channel II (A17) is connected to the feed port I (5-A) of the hydrogen stripping tower (5), the methane-rich pipeline II (202) is connected to the feed port II (5-B) of the hydrogen stripping tower (5), the gas phase outlet (5-D) at the top of the hydrogen stripping tower (5) is connected to the inlet of the medium-pressure hydrogen channel (A4), and the outlet of the medium-pressure hydrogen channel (A4) is connected to the external medium-pressure hydrogen pipeline,The pipeline of the bottom liquid phase outlet (5-E) of the hydrogen stripping tower (5) is divided into a methane-rich pipeline III (203) and a methane-rich pipeline IV (204); the inlet of the methane-rich channel I (A16) is connected to the methane-rich pipeline III (203); the outlet of the methane-rich channel I (A16) is connected to the feed port I (7-A) of the LNG separation tower (7); the methane-rich pipeline IV (204) is connected to the feed port II (7-B) of the LNG separation tower (7); the bottom liquid phase outlet (7-E) of the LNG separation tower (7) is connected to the inlet of the LNG channel (A14); the outlet of the LNG channel (A14) is connected to the off-site LNG storage and transportation pipeline; the top gas phase outlet (7-E) of the LNG separation tower (7) is connected to the inlet of the LNG channel (A14); the outlet of the LNG channel (A14) is connected to the off-site LNG storage and transportation pipeline; The carbon monoxide-rich channel I (B1) of the LNG separation tower condenser (10) is connected to the inlet of the carbon monoxide-rich channel I (B1), the outlet of the carbon monoxide-rich channel I (B1) is connected to the feed port (9-A) of the LNG separation tower reflux tank (9), the bottom liquid phase outlet (9-B) of the LNG separation tower reflux tank (9) is connected to the top feed port (7-D) of the LNG separation tower (7), the top gas phase outlet (9-C) of the LNG separation tower reflux tank (9) is connected to the feed port (11-A) of the N2 / CO separation tower (11), the top gas phase outlet (11-B) of the N2 / CO separation tower (11) is connected to the inlet of the nitrogen-rich channel II (C3), and the outlet of the nitrogen-rich channel II (C3) is connected to the reflux tank (13 ) feed port (13-A), the bottom liquid phase outlet (13-B) of the N2 / CO separation tower reflux tank (13) is connected to the top feed port (11-C) of the N2 / CO separation tower (11), the top gas phase outlet (13-C) of the N2 / CO separation tower reflux tank (13) is connected to the inlet of the nitrogen-rich gas channel I (A5), the outlet of the nitrogen-rich gas channel I (A5) is connected to the nitrogen-rich gas pipeline outside the boundary, the bottom liquid phase outlet (11-D) of the N2 / CO separation tower (11) is connected to the inlet of the CO channel II (C2), the outlet of the CO channel II (C2) is connected to the inlet of the CO channel I (A1), the outlet of the CO channel I (A1) is connected to the CO pipeline outside the boundary, and the mixed refrigerant compressor system The high-pressure liquid phase mixed refrigerant pipeline of the system (15) is connected to the inlet of the high-pressure liquid phase refrigerant channel I (A10), the outlet of the high-pressure liquid phase refrigerant channel I (A10) is connected to the pipe mouth I (A9-A) of the reflux refrigerant channel (A9), the high-pressure gas phase mixed refrigerant of the mixed refrigerant compressor system (15) is connected to the inlet of the high-pressure gas phase refrigerant channel I (A8), the outlet of the high-pressure gas phase refrigerant channel I (A8) is connected to the feed port (3-A) of the MRC low-temperature separator (3), the bottom liquid phase outlet (3-B) of the MRC low-temperature separator (3) is connected to the inlet of the high-pressure liquid phase refrigerant channel II (A13), and the outlet of the high-pressure liquid phase refrigerant channel II (A13) is connected to the inlet of the LNG separation tower reboiler (8),The outlet of the LNG separation tower reboiler (8) is connected to the pipe port II (A9-B) of the reflux refrigerant channel (A9), the top gas phase outlet (3-C) of the MRC low-temperature separator (3) is connected to the inlet of the high-pressure gas phase refrigerant channel II (A12), the outlet of the high-pressure gas phase refrigerant channel II (A12) is connected to the inlet of the hydrogen stripping tower reboiler (6), the outlet of the hydrogen stripping tower reboiler (6) is connected to the pipe port III (A9-C) of the reflux refrigerant channel (A9), the outlet of the reflux refrigerant channel (A9) is connected to the inlet of the mixed refrigerant compressor system (15); the outlet of the nitrogen compression system (16) is connected to the inlet of the high-pressure nitrogen channel I (A6) The outlet of the high-pressure nitrogen channel I (A6) is connected to the inlet of the N2 / CO separation tower reboiler (12), the outlet of the N2 / CO separation tower reboiler (12) is connected to the inlet of the high-pressure nitrogen channel II (A15), the outlet of the high-pressure nitrogen channel II (A15) is connected to the reflux low-pressure nitrogen channel II (B2) and the reflux low-pressure nitrogen channel III (C1), respectively, the outlet of the reflux low-pressure nitrogen channel II (B2) and the outlet of the reflux low-pressure nitrogen channel III (C1) are both connected to the inlet of the reflux low-pressure nitrogen channel I (A7), and the outlet of the reflux low-pressure nitrogen channel I (A7) is connected to the inlet of the nitrogen compression system (16).

2. The device for cryogenic separation of LNG and CO by dual-cycle refrigeration of mixed refrigerant and nitrogen according to claim 1 is characterized in that: The hydrogen stripping tower (5), LNG separation tower (7) and N2 / CO separation tower (11) are packed towers or plate towers.

3. The device for cryogenic separation of LNG and CO by dual-cycle refrigeration of mixed refrigerant and nitrogen according to claim 1, characterized in that: The pipeline at the inlet of the pipe port I (A9-A) of the return refrigerant channel (A9) is provided with a regulating valve a (101), the pipeline at the inlet of the pipe port II (A9-B) of the return refrigerant channel (A9) is provided with a regulating valve b (102), and the pipeline at the inlet of the pipe port III (A9-C) of the return refrigerant channel (A9) is provided with a regulating valve c (103); the pipeline at the bottom liquid phase outlet (2-C) of the heavy hydrocarbon separator (2) is provided with a regulating valve d (104) for controlling the liquid level of the heavy hydrocarbon separator (2); the pipeline at the outlet of the LNG channel (A14) is provided with a regulating valve e (105) for controlling the liquid level of the LNG separation tower (7); the pipeline at the gas phase outlet (4-B) of the low-temperature separator (4) is provided with a regulating valve f (106) 06), used to control the liquid level of the heavy hydrocarbon separator (2); the methane-rich pipeline I (201) of the bottom liquid phase outlet pipeline of the low-temperature separator (4) is provided with a regulating valve g (107), used to control the flow rate of the methane-rich channel II (A17) of the bottom liquid of the low-temperature separator (4); the methane-rich pipeline II (202) of the bottom liquid phase outlet pipeline of the low-temperature separator (4) is provided with a regulating valve h (108), used to control the liquid level of the low-temperature separator (4); a regulating valve i (109) is provided between the inlet pipeline and the outlet pipeline of the hydrogen stripping tower reboiler (6), used to control the temperature of the LNG entering the hydrogen stripping tower (5) bottom kettle; the methane-rich pipeline III (203) of the bottom liquid phase outlet pipeline of the hydrogen stripping tower (5) is provided with a regulating valve j (110) , used to control the flow rate of the bottom liquid of the hydrogen stripping tower (5) to remove the methane-rich channel I (A16); the methane-rich pipeline IV (204) of the bottom liquid phase outlet pipeline of the hydrogen stripping tower (5) is provided with a regulating valve k (111) for controlling the liquid level of the hydrogen stripping tower (5); the inlet pipeline of the reflux low-pressure nitrogen channel II (B2) is provided with a regulating valve l (112) for controlling the temperature of the carbon monoxide-rich gas outlet from the carbon monoxide-rich channel I (B1); the top gas phase outlet (9-C) pipeline of the LNG separation tower reflux tank (9) is provided with a regulating valve m (113) for controlling the pressure of the LNG separation tower (7); the regulating valve n (114) is provided between the inlet pipeline and the outlet pipeline of the LNG separation tower reboiler (8) for controlling the (7) tower bottom temperature; a regulating valve o (115) is provided at the top gas phase outlet (13-C) pipeline of the N2 / CO separation tower reflux tank (13) for controlling the pressure of the N2 / CO separation tower (11); a regulating valve p (116) is provided at the inlet pipeline of the reflux low-pressure nitrogen channel III (C1) for controlling the temperature of the nitrogen-rich gas outlet nitrogen-rich channel II (C3); a regulating valve q (117) is provided at the bottom liquid phase outlet (11-D) pipeline of the N2 / CO separation tower (11) for controlling the liquid level of the N2 / CO separation tower (11); a regulating valve r (118) is provided between the inlet pipeline and the outlet pipeline of the N2 / CO separation tower reboiler (12) for controlling the tower bottom temperature of the N2 / CO separation tower (11);A regulating valve s (119) is provided between the inlet and outlet pipelines of the reflux low-pressure nitrogen channel III (C1); a regulating valve t (120) is provided on the top gas phase outlet (5-D) pipeline of the hydrogen stripping tower (5) to control the pressure of the hydrogen stripping tower (5); the hydrogen stripping tower reboiler (6), the LNG separation tower reboiler (8) and the N2 / CO separation tower reboiler (12) can be internal or external. ;

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