A methane purification system and production method for producing different purities

Abstract

The application belongs to a kind of methane purification system and production method for producing different purity;Including methane crude product pipeline, methane crude product pipeline is connected with the import of cryogenic rectification tower, the outside of cryogenic rectification tower is equipped with heat exchange jacket, the import of heat exchange jacket is connected with liquid nitrogen pipeline;The gas phase outlet of the top of cryogenic rectification tower is connected with 3N grade methane storage tank and depth adsorption unit respectively through the first heat exchange channel of main heat exchanger, depth adsorption unit is connected with 3.5N grade-5N grade methane storage tank through the second heat exchange channel of main heat exchanger, three-way is arranged between second heat exchange channel and 3.5N grade-5N grade methane storage tank, the third end of three-way is connected with 9N grade methane storage tank through depth purification unit;It has the characteristics of small investment, simple operation, low energy consumption and maintenance difficulty, and the application can also produce different purity of methane according to market demand, to meet market demand and improve the profit ability of enterprise.

Description

Technical Field

[0001] This invention belongs to the field of methane purification technology, and particularly relates to a methane purification system and production method for producing methane of different purities. Background Technology

[0002] Methane, the simplest organic compound, has the chemical formula CH4. It is a colorless and odorless gas at room temperature and pressure. It is a stable gas that is lighter than air and extremely insoluble in water. The methane molecule has a tetrahedral structure with a carbon atom at the center and four hydrogen atoms at the vertices. Methane of different purities has different uses. For example, methane comprising about 87% (i.e., natural gas) is usually used as a feedstock; 3N grade methane can be used as a feedstock for syngas preparation; 3.5N to 5N grade methane can be used as a feedstock for specialty syngas and for high-end instrument calibration; 9N grade methane can be used to prepare advanced semiconductors or for precise combustion dynamics experiments. Furthermore, conventional methane purification mostly employs multi-stage cryogenic distillation, a technology that consumes a huge amount of energy, requires high equipment investment, and has a complex process. It requires multiple distillation columns and supporting condensation and reboiling systems, resulting in a large footprint and high difficulty in operation and maintenance. Moreover, existing purification systems are usually designed for a single purity level, lacking flexible adjustment capabilities and unable to produce high-purity methane products of different specifications on demand within the same system, making it difficult to adapt to the diverse gas purity requirements of downstream applications. Summary of the Invention

[0003] To overcome the above deficiencies, the present invention provides a purification system and production method for producing methane of different purities, thereby solving the technical problems existing in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A methane purification system for producing methane of different purities includes a crude methane pipeline connected to the inlet of a cryogenic distillation column. The cryogenic distillation column is externally equipped with a heat exchange jacket, the inlet of which is connected to a liquid nitrogen pipeline. The top gas phase outlet of the cryogenic distillation column is connected to a 3N-grade methane storage tank and a deep adsorption unit via a first heat exchange channel of the main heat exchanger. The deep adsorption unit is connected to 3.5N- to 5N-grade methane storage tanks via a second heat exchange channel of the main heat exchanger. A T-junction is provided between the second heat exchange channel and the 3.5N- to 5N-grade methane storage tanks, and the third end of the T-junction is connected to a 9N-grade methane storage tank via the deep purification unit.

[0005] The beneficial effects of this invention are as follows: by constructing a combined process of distillation, adsorption, and purification, and by using liquid nitrogen for single-tower cryogenic distillation to remove most of the heavy hydrocarbon impurities, and with the subsequent adsorption and purification, methane can be purified to the 9N grade. Furthermore, this invention can achieve the extraction of methane of various purities in different stages, that is, in actual production, methane of different purities can be produced according to market demand, so as to meet market demand and improve the profitability of enterprises.

[0006] Preferably, the deep adsorption unit includes several adsorbers arranged in parallel.

[0007] Preferably, the third end of the three-way valve is connected to the third heat exchange channel of the main heat exchanger through a purifier in the deep purification unit, and the outlet of the third heat exchange channel of the main heat exchanger is connected to a 9N-grade methane storage tank through a filter.

[0008] Preferably, the liquid phase outlet at the bottom of the cryogenic distillation column is connected to the drain pipe through the fourth heat exchange channel of the main heat exchanger.

[0009] Preferably, the outlet of the heat exchange jacket is connected to a nitrogen venting pipe with a first valve through the fifth heat exchange channel of the main heat exchanger.

[0010] Preferably, a second valve is provided between the outlet of the first heat exchange channel of the main heat exchanger and the 3N-grade methane storage tank, and a third valve is provided between the outlet of the first heat exchange channel of the main heat exchanger and the deep adsorption unit; a fourth valve is provided between the deep adsorption unit and the second heat exchange channel of the main heat exchanger, a fifth valve is provided between the second heat exchange channel and the 3.5N-grade to 5N-grade methane storage tank, and a sixth valve is provided between the third end of the tee and the deep purification unit.

[0011] Preferably, the adsorber is provided with a corresponding adsorber inlet valve at the inlet and a corresponding adsorber outlet valve at the outlet.

[0012] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from the crude methane pipeline enters the cryogenic distillation column. Simultaneously, liquid nitrogen from the liquid nitrogen pipeline enters the heat exchange jacket to exchange heat with the crude methane in the cryogenic distillation column, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in the cryogenic distillation column is -90 to -110°C. Step 2: After heat exchange in the heat exchange jacket, the nitrogen gas passes through the fifth heat exchange channel of the main heat exchanger and then enters the nitrogen venting pipe through the first valve for venting; the temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process through the drain pipe; the bottom liquid in the fourth heat exchange channel of the main heat exchanger is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column enters the first heat exchange channel of the main heat exchanger through the gas phase outlet at the top of the cryogenic distillation column for heat exchange. After heat exchange, it enters the 3N-class methane storage tank through the second valve for temporary storage and awaits sale. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger is 15-25℃. Step 5: When high-purity methane is required, it is heat-exchanged through the first heat exchange channel of the main heat exchanger and then enters the corresponding adsorber through the third valve for adsorption. Ethane, propane and butane are adsorbed to reduce heavy hydrocarbon impurities to the ppm level; the temperature of the methane after passing through adsorber 9 is 40-45℃. Step 6: After adsorption by the adsorber in Step 5, the methane passes through the second heat exchange channel of the main heat exchanger and then enters the 3.5N to 5N methane storage tank through the fifth valve for temporary storage and awaiting sale; the temperature of the methane passing through the second heat exchange channel of the main heat exchanger is 15 to 25°C. Step 7: When higher purity methane is required, it passes through the second heat exchange channel of the main heat exchanger and then enters the purifier through the sixth valve for purification; a very small amount of ethane and propane impurities are removed by the purifier 10; the temperature of the methane after passing through the purifier is 35-45℃. Step 8: The purified methane passes through the third heat exchange channel of the main heat exchanger and the filter before entering the 9N-class methane storage tank for temporary storage and awaiting sale; the temperature of the methane passing through the third heat exchange channel of the main heat exchanger is 15-25℃; the filter is mainly used to remove solid particulate impurities.

[0013] According to the above scheme, a purification system and production method for producing methane of different purities are constructed. This invention establishes a combined process of distillation, adsorption, and purification. The distillation adopts a single-tower distillation method, in which liquid nitrogen is introduced into the heat exchange jacket to deeply cool the crude methane, thereby removing most of the heavy hydrocarbon impurities. Furthermore, high-purity methane is obtained through adsorption and purification. Compared with traditional multi-stage cryogenic distillation, this invention has the advantages of low investment, simple operation, low energy consumption, and low maintenance difficulty. At the same time, this invention can also produce methane of different purities according to market demand, thereby meeting market demand and improving corporate profitability. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention.

[0015] Legend: 1. Crude methane pipeline; 2. Cryogenic distillation column; 3. Heat exchange jacket; 4. Liquid nitrogen pipeline; 5. Main heat exchanger; 6. 3N-class methane storage tank; 7. 3.5N-class to 5N-class methane storage tank; 8. 9N-class methane storage tank; 9. Adsorber; 10. Purifier; 11. Filter; 12. Drainage pipeline; 13. First valve; 14. Second valve; 15. Third valve; 16. Fourth valve; 17. Fifth valve; 18. Sixth valve; 19. Adsorber inlet valve; 20. Adsorber outlet valve. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Reference Figure 1 This invention relates to a methane purification system and method for producing methane of different purities. The methane purification system includes a crude methane pipeline 1, which is connected to the inlet of a cryogenic distillation column 2. The cryogenic distillation column 2 is equipped with a heat exchange jacket 3, the inlet of which is connected to a liquid nitrogen pipeline 4. The top gas phase outlet of the cryogenic distillation column 3 is connected to a 3N-grade methane storage tank 6 and a deep adsorption unit through the first heat exchange channel of the main heat exchanger 5. The deep adsorption unit is connected to a 3.5N-grade to 5N-grade methane storage tank 7 through the second heat exchange channel of the main heat exchanger 5. A T-junction is provided between the second heat exchange channel and the 3.5N-grade to 5N-grade methane storage tank 7, and the third end of the T-junction is connected to a 9N-grade methane storage tank 8 through the deep purification unit. This invention constructs a combined process of distillation, adsorption, and purification. In this combined process, 3N-grade methane can be extracted from the gas phase of the cryogenic distillation column 2, 3.5N-grade to 5N-grade methane can be extracted through the deep adsorption unit, and 9N-grade methane can be obtained through the deep purification unit. The cryogenic distillation column 2 in this invention differs from the multi-stage cryogenic distillation in traditional technology. Instead, it adopts a single-column distillation method combined with liquid nitrogen (as a refrigerant) to deeply cool the crude methane, reducing the temperature of the crude methane to -90 to -110°C, thereby achieving the purpose of removing heavy hydrocarbon impurities from the crude methane.

[0018] Furthermore, the deep adsorption unit includes several adsorbers 9 arranged in parallel. This invention can use multiple adsorbers, with some adsorbers 9 in operation and others in regeneration mode during operation. This arrangement enables continuous system operation. Figure 1 The present invention can have six adsorbers 9, with three operating and three regenerating under normal circumstances. Even if a single adsorber 9 requires emergency repair, it will not affect the normal operation of the entire system. The adsorber 9 in this invention utilizes the adsorption of different gases by the adsorbent to achieve gas separation. Specifically, in this invention, 3N-grade methane products can pass through the adsorber 9, adsorbing away small amounts of ethane, propane, and butane impurities, reducing heavy hydrocarbon impurities to the ppm level, resulting in 3.5N to 5N methane products.

[0019] Furthermore, the third end of the three-way valve is connected to the third heat exchange channel of the main heat exchanger 5 via the purifier 10 in the deep purification unit, and the outlet of the third heat exchange channel of the main heat exchanger 5 is connected to the 9N-grade methane storage tank 8 via the filter 11. The purifier 10 described in this invention pertains to a fine processing process, used to handle smaller flow rates of gas, aiming to remove almost all trace impurities and a very small amount of ethane and propane impurities to achieve extremely high purity. Furthermore, by setting the filter 11, the requirement of "ultimate purity" for 9N-grade methane products can be met by removing solid particulate impurities (metallic or non-metallic particles), thereby ensuring the quality of the final product.

[0020] Furthermore, the liquid phase outlet at the bottom of the cryogenic distillation column 2 is connected to the drain pipe 12 via the fourth heat exchange channel of the main heat exchanger 5. The above-described configuration of the present invention enables full utilization of cooling capacity, achieving energy saving and consumption reduction.

[0021] Furthermore, the outlet of the heat exchange jacket 3 is connected to a nitrogen venting pipe with a first valve 13 via the fifth heat exchange channel of the main heat exchanger 5. The above-described configuration of the present invention enables full utilization of cooling capacity, achieving energy saving and consumption reduction.

[0022] Furthermore, a second valve 14 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the 3N-grade methane storage tank 6; a third valve 15 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the deep adsorption unit; a fourth valve 16 is provided between the deep adsorption unit and the second heat exchange channel of the main heat exchanger 5; a fifth valve 17 is provided between the second heat exchange channel and the 3.5N-grade to 5N-grade methane storage tank 7; and a sixth valve 18 is provided between the third end of the tee and the deep purification unit. Through the above configuration, the present invention achieves the characteristics of easy operation and convenient extraction of methane of different purities. In actual production, the present invention can extract a single methane of different purities, or extract any two different purities of methane, or simultaneously extract three purities of methane products, to flexibly adjust the product according to market demand.

[0023] Furthermore, the adsorber 9 is provided with a corresponding adsorber inlet valve 19 at its inlet and a corresponding adsorber outlet valve 20 at its outlet.

[0024] The present invention also provides a production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, the gas phase enters the 3N-level methane storage tank 6 through the second valve 14 for temporary storage and awaiting sale. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 5: When high-purity methane is required, it is heat-exchanged through the first heat exchange channel of the main heat exchanger 5 and then enters the corresponding adsorber 9 through the third valve 15 for adsorption. Ethane, propane and butane are adsorbed to reduce heavy hydrocarbon impurities to the ppm level; the temperature of the methane after passing through the adsorber 9 is 40-45℃. Step 6: After adsorption by the adsorber 9 in step 5, the methane passes through the second heat exchange channel of the main heat exchanger 5 and then enters the 3.5N to 5N methane storage tank 7 through the fifth valve 17 for temporary storage and awaiting sale; the temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15 to 25°C. Step 7: When higher purity methane is required, it passes through the second heat exchange channel of the main heat exchanger 5 and then enters the purifier 10 through the sixth valve 18 for purification. The purifier 10 removes a very small amount of ethane and propane impurities. The temperature of the methane after passing through the purifier 10 is 35-45℃. Step 8: The purified methane passes through the third heat exchange channel of the main heat exchanger 5 and the filter 11 before entering the 9N-grade methane storage tank 8 for temporary storage and awaiting sale; the temperature of the methane passing through the third heat exchange channel of the main heat exchanger 5 is 15-25℃; the filter 11 is mainly used to remove solid particulate impurities.

[0025] This invention employs a process combining a cryogenic distillation column, a deep adsorption unit, and a deep purification unit. The cryogenic distillation column utilizes liquid nitrogen to cryogenically cool crude methane, achieving the main separation task and removing most of the heavy hydrocarbon components (ethane, propane, and butane). Compared to traditional multi-stage distillation column designs, this significantly reduces equipment investment and operating energy consumption. Furthermore, the deep adsorption unit ensures uninterrupted purification (with one part in operation and another in regeneration, alternating between the two), guaranteeing production continuity and stability. The combination of the cryogenic distillation column and the deep adsorption unit in this invention utilizes deep... Cold distillation is used for coarse separation to remove a large number of impurities; then adsorption is used for fine removal to remove trace impurities remaining from cryogenic residue. This combination not only produces 9N-grade products to meet the purity requirements of high-end customers, but also effectively protects the subsequent precision purifiers, achieving continuous production while extending the purifier's lifespan. Furthermore, this invention allows for flexible adjustment of the produced products to meet market demands. In actual production, it can simultaneously produce three different purities of methane, or extract any one or more different purities of methane, thereby meeting market needs and improving corporate profitability.

[0026] To explain the present invention in more detail, it will now be further illustrated with reference to the embodiments. Specific embodiments are as follows: Example 1 A methane purification system for producing methane of varying purities includes a crude methane pipeline 1 connected to the inlet of a cryogenic distillation column 2. The cryogenic distillation column 2 is externally equipped with a heat exchange jacket 3, the inlet of which is connected to a liquid nitrogen pipeline 4. The top gas phase outlet of the cryogenic distillation column 3 is connected to a 3N-stage methane storage tank 6 and a deep adsorption unit via a first heat exchange channel of a main heat exchanger 5. The deep adsorption unit is connected to a 3.5N- to 5N-stage methane storage tank 7 via a second heat exchange channel of the main heat exchanger 5. A T-junction is provided between the second heat exchange channel and the 3.5N- to 5N-stage methane storage tank 7, with the third end of the T-junction connected to a 9N-stage methane storage tank 8 via the deep purification unit. The deep adsorption unit includes several adsorbers 9 connected in parallel. The third end of the tee is connected to the third heat exchange channel of the main heat exchanger 5 via the purifier 10 in the deep purification unit. The outlet of the third heat exchange channel of the main heat exchanger 5 is connected to the 9N-grade methane storage tank 8 via the filter 11. The liquid phase outlet at the bottom of the cryogenic distillation column 2 is connected to the drain pipe 12 via the fourth heat exchange channel of the main heat exchanger 5. The outlet of the heat exchange jacket 3 is connected to the nitrogen vent pipe with the first valve 13 via the fifth heat exchange channel of the main heat exchanger 5. A second valve 14 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the 3N-grade methane storage tank 6; a third valve 15 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the deep adsorption unit; a fourth valve 16 is provided between the deep adsorption unit and the second heat exchange channel of the main heat exchanger 5; a fifth valve 17 is provided between the second heat exchange channel and the 3.5N-grade to 5N-grade methane storage tank 7; and a sixth valve 18 is provided between the third end of the tee and the deep purification unit. The adsorber 9 is provided with a corresponding adsorber inlet valve 19 at its inlet and a corresponding adsorber outlet valve 20 at its outlet.

[0027] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, the gas phase enters the 3N-level methane storage tank 6 through the second valve 14 for temporary storage and awaiting sale. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃.

[0028] Example 2 A methane purification system for producing methane of varying purities includes a crude methane pipeline 1 connected to the inlet of a cryogenic distillation column 2. The cryogenic distillation column 2 is externally equipped with a heat exchange jacket 3, the inlet of which is connected to a liquid nitrogen pipeline 4. The top gas phase outlet of the cryogenic distillation column 3 is connected to a 3N-stage methane storage tank 6 and a deep adsorption unit via a first heat exchange channel of a main heat exchanger 5. The deep adsorption unit is connected to a 3.5N- to 5N-stage methane storage tank 7 via a second heat exchange channel of the main heat exchanger 5. A T-junction is provided between the second heat exchange channel and the 3.5N- to 5N-stage methane storage tank 7, with the third end of the T-junction connected to a 9N-stage methane storage tank 8 via the deep purification unit. The deep adsorption unit includes several adsorbers 9 connected in parallel. The third end of the tee is connected to the third heat exchange channel of the main heat exchanger 5 via the purifier 10 in the deep purification unit. The outlet of the third heat exchange channel of the main heat exchanger 5 is connected to the 9N-grade methane storage tank 8 via the filter 11. The liquid phase outlet at the bottom of the cryogenic distillation column 2 is connected to the drain pipe 12 via the fourth heat exchange channel of the main heat exchanger 5. The outlet of the heat exchange jacket 3 is connected to the nitrogen vent pipe with the first valve 13 via the fifth heat exchange channel of the main heat exchanger 5. A second valve 14 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the 3N-grade methane storage tank 6; a third valve 15 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the deep adsorption unit; a fourth valve 16 is provided between the deep adsorption unit and the second heat exchange channel of the main heat exchanger 5; a fifth valve 17 is provided between the second heat exchange channel and the 3.5N-grade to 5N-grade methane storage tank 7; and a sixth valve 18 is provided between the third end of the tee and the deep purification unit. The adsorber 9 is provided with a corresponding adsorber inlet valve 19 at its inlet and a corresponding adsorber outlet valve 20 at its outlet.

[0029] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: When high-purity methane is required, the gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, it enters the corresponding adsorber 9 through the third valve 15 for adsorption, adsorbing ethane, propane, and butane, reducing heavy hydrocarbon impurities to the ppm level. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃; the temperature of the methane after passing through the adsorber 9 is 40-45℃. Step 5: After adsorption by the adsorber 9 in step 4, the methane passes through the second heat exchange channel of the main heat exchanger 5 and then enters the 3.5N to 5N methane storage tank 7 through the fifth valve 17 for temporary storage and awaiting sale; the temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15 to 25°C.

[0030] Example 3 A methane purification system for producing methane of varying purities includes a crude methane pipeline 1 connected to the inlet of a cryogenic distillation column 2. The cryogenic distillation column 2 is externally equipped with a heat exchange jacket 3, the inlet of which is connected to a liquid nitrogen pipeline 4. The top gas phase outlet of the cryogenic distillation column 3 is connected to a 3N-stage methane storage tank 6 and a deep adsorption unit via a first heat exchange channel of a main heat exchanger 5. The deep adsorption unit is connected to a 3.5N- to 5N-stage methane storage tank 7 via a second heat exchange channel of the main heat exchanger 5. A T-junction is provided between the second heat exchange channel and the 3.5N- to 5N-stage methane storage tank 7, with the third end of the T-junction connected to a 9N-stage methane storage tank 8 via the deep purification unit. The deep adsorption unit includes several adsorbers 9 connected in parallel. The third end of the tee is connected to the third heat exchange channel of the main heat exchanger 5 via the purifier 10 in the deep purification unit. The outlet of the third heat exchange channel of the main heat exchanger 5 is connected to the 9N-grade methane storage tank 8 via the filter 11. The liquid phase outlet at the bottom of the cryogenic distillation column 2 is connected to the drain pipe 12 via the fourth heat exchange channel of the main heat exchanger 5. The outlet of the heat exchange jacket 3 is connected to the nitrogen vent pipe with the first valve 13 via the fifth heat exchange channel of the main heat exchanger 5. A second valve 14 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the 3N-grade methane storage tank 6; a third valve 15 is provided between the outlet of the first heat exchange channel of the main heat exchanger 5 and the deep adsorption unit; a fourth valve 16 is provided between the deep adsorption unit and the second heat exchange channel of the main heat exchanger 5; a fifth valve 17 is provided between the second heat exchange channel and the 3.5N-grade to 5N-grade methane storage tank 7; and a sixth valve 18 is provided between the third end of the tee and the deep purification unit. The adsorber 9 is provided with a corresponding adsorber inlet valve 19 at its inlet and a corresponding adsorber outlet valve 20 at its outlet.

[0031] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, it enters the corresponding adsorber 9 through the third valve 15 for adsorption, adsorbing ethane, propane, and butane to reduce heavy hydrocarbon impurities to the ppm level. The temperature of methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃; the temperature of methane after passing through the adsorber 9 is 40-45℃. Step 5: After adsorption by the adsorber 9 in step 4, the methane passes through the second heat exchange channel of the main heat exchanger 5 and then enters the purifier 10 through the sixth valve 18 for purification. The purifier 10 removes a very small amount of ethane and propane impurities. The temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15-25℃. The temperature of the methane after passing through the purifier 10 is 35-45℃. Step 6: The purified methane passes through the third heat exchange channel of the main heat exchanger 5 and the filter 11 before entering the 9N-class methane storage tank 8 for temporary storage and awaiting sale; the temperature of the methane passing through the third heat exchange channel of the main heat exchanger 5 is 15-25℃; the filter 11 is mainly used to remove solid particulate impurities.

[0032] Example 4 A methane purification system for producing methane of different purities has the same structure as in Example 1, so the structure will not be described again.

[0033] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, part of the methane enters the 3N-grade methane storage tank 6 through the second valve 14 for temporary storage and awaiting sale. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃. The other part of the methane enters the corresponding adsorber 9 through the third valve 15 for adsorption, adsorbing ethane, propane, and butane, reducing heavy hydrocarbon impurities to the ppm level. The temperature of the methane after passing through the adsorber 9 is 40-45℃. Step 5: After adsorption by the adsorber 9 in step 4, the methane passes through the second heat exchange channel of the main heat exchanger 5 and then enters the 3.5N to 5N methane storage tank 7 through the fifth valve 17 for temporary storage and awaiting sale; the temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15 to 25°C.

[0034] Example 5 A methane purification system for producing methane of different purities has the same structure as in Example 1, so the structure will not be described again.

[0035] Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, it enters the corresponding adsorber 9 through the third valve 15 for adsorption, adsorbing ethane, propane, and butane to reduce heavy hydrocarbon impurities to the ppm level. The temperature of methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃; the temperature of methane after passing through the adsorber 9 is 40-45℃. Step 5: After adsorption by the adsorber 9 in Step 4, the methane is heat-exchanged through the second heat exchange channel of the main heat exchanger 5. After heat exchange, a portion of the methane enters the 3.5N to 5N methane storage tank 7 through the fifth valve 17 for temporary storage and awaiting sale, while the other portion of the methane enters the purifier 10 through the sixth valve 18 for purification. The temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15 to 25°C. The purifier 10 removes a very small amount of ethane and propane impurities. The temperature of the methane after passing through the purifier 10 is 35 to 45°C. Step 6: The purified methane passes through the third heat exchange channel of the main heat exchanger 5 and the filter 11 before entering the 9N-class methane storage tank 8 for temporary storage and awaiting sale; the temperature of the methane passing through the third heat exchange channel of the main heat exchanger 5 is 15-25℃; the filter 11 is mainly used to remove solid particulate impurities.

[0036] Example 6 A methane purification system for producing methane of different purities has the same structure as in Example 1, so the structure will not be described again.

[0037] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, part of the methane enters the 3N-class methane storage tank 6 through the second valve 14 for temporary storage and awaiting sale; the other part of the methane enters the corresponding adsorber 9 through the third valve 15 for adsorption, adsorbing ethane, propane, and butane to reduce heavy hydrocarbon impurities to the ppm level; the temperature of the methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃; the temperature of the methane after passing through the adsorber 9 is 40-45℃. Step 5: After adsorption by the adsorber 9 in step 4, the methane passes through the second heat exchange channel of the main heat exchanger 5 and then enters the purifier 10 through the sixth valve 18 for purification. The purifier 10 removes a very small amount of ethane and propane impurities. The temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15-25℃. The temperature of the methane after passing through the purifier 10 is 35-45℃. Step 6: The purified methane passes through the third heat exchange channel of the main heat exchanger 5 and the filter 11 before entering the 9N-class methane storage tank 8 for temporary storage and awaiting sale; the temperature of the methane passing through the third heat exchange channel of the main heat exchanger 5 is 15-25℃; the filter 11 is mainly used to remove solid particulate impurities.

[0038] Example 7 A methane purification system for producing methane of different purities has the same structure as in Example 1, so the structure will not be described again.

[0039] A production method for a methane purification system for producing methane of different purities, the method comprising the following steps: Step 1: Crude methane from crude methane pipeline 1 enters cryogenic distillation column 2. Simultaneously, liquid nitrogen from liquid nitrogen pipeline 4 enters heat exchange jacket 3 to exchange heat with the crude methane in cryogenic distillation column 2, removing most of the ethane, propane, and butane. The temperature of the crude methane is 30°C, and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane, and butane. After heat exchange, the temperature of the material in cryogenic distillation column 2 is -90°C to -110°C. Step 2: After heat exchange in the heat exchange jacket 3, the nitrogen gas is vented through the fifth heat exchange channel of the main heat exchanger 5 and then enters the nitrogen venting pipe through the first valve 13. The temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger 5 is 15-25℃. Step 3: The bottom liquid in the cryogenic distillation column 2 enters the fourth heat exchange channel of the main heat exchanger 5 through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process for processing through the drain pipe 12; the bottom liquid in the fourth heat exchange channel of the main heat exchanger 5 is vaporized and heated to 15-25℃. Step 4: The gas phase in the cryogenic distillation column 2 enters the first heat exchange channel of the main heat exchanger 5 through the gas phase outlet at the top of the cryogenic distillation column 2 for heat exchange. After heat exchange, part of the methane enters the 3N-grade methane storage tank 6 through the second valve 14 for temporary storage and awaiting sale. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger 5 is 15-25℃. The other part of the methane enters the corresponding adsorber 9 through the third valve 15 for adsorption, adsorbing ethane, propane, and butane, reducing heavy hydrocarbon impurities to the ppm level. The temperature of the methane after passing through the adsorber 9 is 40-45℃. Step 5: After adsorption by the adsorber 9 in Step 4, the methane passes through the second heat exchange channel of the main heat exchanger 5. After heat exchange through the second heat exchange channel, a portion of the methane enters the 3.5N-5N methane storage tank 7 through the fifth valve 17 for temporary storage pending sale. The other portion of the methane, after heat exchange through the second heat exchange channel, enters the purifier 10 through the sixth valve 18 for purification. The temperature of the methane passing through the second heat exchange channel of the main heat exchanger 5 is 15-25℃. The purifier 10 removes a very small amount of ethane and propane impurities. The temperature of the methane after passing through the purifier 10 is 35-45℃. Step 6: The purified methane passes through the third heat exchange channel of the main heat exchanger 5 and the filter 11 before entering the 9N-class methane storage tank 8 for temporary storage and awaiting sale; the temperature of the methane passing through the third heat exchange channel of the main heat exchanger 5 is 15-25℃; the filter 11 is mainly used to remove solid particulate impurities.

[0040] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A purification system for producing methane of different purities, characterized in that: The methane purification system includes a crude methane pipeline (1), which is connected to the inlet of a cryogenic distillation column (2). The cryogenic distillation column (2) is equipped with a heat exchange jacket (3) on its exterior, and the inlet of the heat exchange jacket (3) is connected to a liquid nitrogen pipeline (4). The top vapor outlet of the cryogenic distillation column (3) is connected to the 3N-stage methane storage tank (6) and the deep adsorption unit through the first heat exchange channel of the main heat exchanger (5). The deep adsorption unit is connected to the 3.5N to 5N methane storage tank (7) through the second heat exchange channel of the main heat exchanger (5). A three-way valve is provided between the second heat exchange channel and the 3.5N to 5N methane storage tank (7). The third end of the three-way valve is connected to the 9N methane storage tank (8) through the deep purification unit.

2. The methane purification system for producing methane of different purities according to claim 1, characterized in that: The deep adsorption unit includes several adsorbers (9) arranged in parallel.

3. The methane purification system for producing methane of different purities according to claim 1, characterized in that: The third end of the three-way valve is connected to the third heat exchange channel of the main heat exchanger (5) through the purifier (10) in the deep purification unit. The outlet of the third heat exchange channel of the main heat exchanger (5) is connected to the 9N-grade methane storage tank (8) through the filter (11).

4. A methane purification system for producing methane of different purities according to claim 1, characterized in that: The liquid phase outlet at the bottom of the cryogenic distillation column (2) is connected to the sewage pipe (12) through the fourth heat exchange channel of the main heat exchanger (5).

5. A methane purification system for producing methane of different purities according to claim 1, characterized in that: The outlet of the heat exchange jacket (3) is connected to the nitrogen venting pipe with the first valve (13) through the fifth heat exchange channel of the main heat exchanger (5).

6. A purification system for producing methane of different purities according to claim 1, characterized in that: A second valve (14) is provided between the outlet of the first heat exchange channel of the main heat exchanger (5) and the 3N-level methane storage tank (6), and a third valve (15) is provided between the outlet of the first heat exchange channel of the main heat exchanger (5) and the deep adsorption unit. A fourth valve (16) is provided between the deep adsorption unit and the second heat exchange channel of the main heat exchanger (5), a fifth valve (17) is provided between the second heat exchange channel and the 3.5N-5N methane storage tank (7), and a sixth valve (18) is provided between the third end of the tee and the deep purification unit.

7. A purification system for producing methane of different purities according to claim 2, characterized in that: The adsorber (9) is provided with a corresponding adsorber inlet valve (19) at the inlet and a corresponding adsorber outlet valve (20) at the outlet.

8. A production method for a methane purification system for producing methane of different purities, characterized in that: The method includes the following steps: Step 1: Crude methane in the crude methane pipeline (1) enters the cryogenic distillation column (2). At the same time, liquid nitrogen in the liquid nitrogen pipeline (4) enters the heat exchange jacket (3) to exchange heat with the crude methane in the cryogenic distillation column (2) to remove most of the ethane, propane and butane. The temperature of the crude methane is 30°C and the temperature of the liquid nitrogen is -196°C. The purity of the crude methane is 99%, and the main impurities include ethane, propane and butane. After heat exchange, the temperature of the material in the cryogenic distillation column (2) is -90 to -110°C. Step 2: After the nitrogen gas in the heat exchange jacket (3) is heated, it is vented through the fifth heat exchange channel of the main heat exchanger (5) and then enters the nitrogen venting pipe through the first valve (13); the temperature of the nitrogen gas after passing through the fifth heat exchange channel of the main heat exchanger (5) is 15-25℃. Step 3: The bottom liquid of the cryogenic distillation column (2) enters the fourth heat exchange channel of the main heat exchanger (5) through its liquid phase outlet for heat exchange, and after heat exchange, it enters the subsequent process through the drain pipe (12) for processing; the bottom liquid of the column through the fourth heat exchange channel of the main heat exchanger (5) is vaporized and heated to 15-25℃; Step 4: The gas phase in the cryogenic distillation column (2) enters the first heat exchange channel of the main heat exchanger (5) through the gas phase outlet at the top of the cryogenic distillation column (2) for heat exchange. After heat exchange, the second valve (14) enters the 3N-grade methane storage tank (6) for temporary storage and waiting for external sale. The temperature of the methane passing through the first heat exchange channel of the main heat exchanger (5) is 15-25℃. Step 5: When high-purity methane is required, after heat exchange through the first heat exchange channel of the main heat exchanger (5), it enters the corresponding adsorber (9) through the third valve (15) for adsorption, adsorbing ethane, propane and butane, reducing heavy hydrocarbon impurities to the ppm level; the temperature of the methane after passing through the adsorber (9) is 40-45℃. Step 6: After adsorption by the adsorber (9) in step 5, the methane is transferred through the second heat exchange channel of the main heat exchanger (5) and then through the fifth valve (17) into the 3.5N-5N methane storage tank (7) for temporary storage and waiting to be sold; the temperature of the methane through the second heat exchange channel of the main heat exchanger (5) is 15-25℃. Step 7: When it is necessary to produce methane with higher purity, after heat exchange through the second heat exchange channel of the main heat exchanger (5), it enters the purifier (10) through the sixth valve (18) for purification; a very small amount of ethane and propane impurities are removed by the purifier (10); the temperature of the methane after passing through the purifier (10) is 35-45℃. Step 8: The purified methane passes through the third heat exchange channel of the main heat exchanger (5) and the filter (11) and is then temporarily stored in the 9N methane storage tank (8) for sale. The temperature of the methane passing through the third heat exchange channel of the main heat exchanger (5) is 15-25°C. The filter (11) is mainly used to remove solid particulate impurities.

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