Device and method for preparing high-pressure CO through nitrogen throttling CO pump pressurization dehydrogenation and demethanization

Abstract

The invention discloses a device and a method for preparing high-pressure CO through pressurized dehydrogenation and demethanization of a nitrogen throttling CO pump, and belongs to the technical field of chemical cryogenic separation. The device comprises a first heat exchanger, a second heat exchanger, a stripping tower reboiler, a hydrogen-rich gas flash tank, a stripping tower, a demethanizing tower, a demethanizing tower reboiler, a demethanizing tower condenser, a demethanizing tower separating tank and a CO liquid pump which are arranged in a cold box, and a nitrogen circulating compressor and a liquid nitrogen supplementing device which are arranged outside the cold box. Nitrogen from a nitrogen cycle compressor provides nitrogen cycle refrigeration for a cold box, pre-cooled nitrogen provides heat for a demethanizer reboiler and is further throttled to provide cold energy for a demethanizer condenser, gas-phase CO at the top of the demethanizer is completely condensed into liquid CO, and the liquid CO is discharged out of a demethanizer separation tank, pressurized by a CO liquid pump, reheated and discharged out of the cold box to prepare a high-pressure CO product. The device simplifies the complex structure of the original CO multi-stage compression system, has the advantages of high compression efficiency, short construction period, high safety level and the like, and is more stable and reliable in operation.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic separation technology in the chemical industry, specifically relating to a nitrogen-throttling CO pump pressurized dehydrogenation and demethanization device and method for producing high-pressure CO. Background Technology

[0002] In chemical production, high-pressure CO is a direct raw material for the synthesis reactions of various fine chemicals such as methanol, acetic acid, and polycarbonate. Its purity and pressure stability directly affect the operating efficiency and product yield of downstream reactors. The HyCO separation process, commonly used in industry, enables large-scale separation and purification of CO. This process mainly includes multiple units such as hydrogen-rich flash tank separation of hydrogen-rich gas, stripping tower distillation dehydrogenation, and demethanizing tower distillation demethanization. To provide sufficient cooling for the cold box separation process and meet the output requirements of high-pressure CO, a multi-stage CO circulation compression system is typically installed outside the cold box. However, this compression system has a complex structure, high equipment investment and maintenance costs, making backup configuration difficult and hindering the implementation of a "one-for-one" operation mode. A malfunction or the need for maintenance will cause the entire CO pressurization system to shut down. Furthermore, the low integration of this system and long delivery and installation cycles limit the integrated design and rapid engineering implementation of the unit. Simultaneously, CO, as a toxic gas, poses a potential leakage risk during long-term operation, posing significant safety hazards and requiring high levels of equipment sealing and safety.

[0003] Therefore, while ensuring the purity of CO products separated by the HyCO separation system, it is urgent to develop a simpler CO compression and cold box refrigeration system and method to reduce system complexity, reduce investment costs, and shorten the construction period. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a nitrogen-throttling CO pump pressurized dehydrogenation and demethanization apparatus and method for producing high-pressure CO.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention provides a nitrogen-throttling CO pump pressurized dehydrogenation and demethanization device for producing high-pressure CO, comprising a first heat exchanger, a second heat exchanger, a stripping tower reboiler, a hydrogen-rich flash tank, a stripping tower, a demethanization tower, a demethanization tower reboiler, a demethanization tower condenser, a demethanization tower separator, and a CO liquid pump disposed in a cold box, as well as a nitrogen circulation compressor and a liquid nitrogen replenishment device outside the cold box;

[0007] The purified gas from upstream passes through the first heat exchanger, the stripping tower reboiler, and the second heat exchanger for cooling before entering the hydrogen-rich flash tank. The liquid phase at the bottom of the hydrogen-rich flash tank enters the stripping tower for further separation. The liquid phase at the bottom of the stripping tower enters the demethanizer for demethanization treatment. The gas phase at the top of the demethanizer is completely condensed by the demethanizer condenser and then enters the demethanizer separator. The liquid phase at the bottom of the demethanizer separator is pressurized by the CO liquid pump and then passes through the second heat exchanger and the first heat exchanger for reheating to obtain high-pressure CO product that exits the cold box. Nitrogen from the nitrogen cycle compressor provides nitrogen cycle refrigeration for the cold box, and liquid nitrogen from the liquid nitrogen replenishment device provides supplemental cooling capacity for the cold box.

[0008] As a preferred option, the specific structure is as follows:

[0009] The first hot-side inlet of the first heat exchanger receives purified gas from upstream, and the first cold-side outlet of the first heat exchanger is connected to the hot-side inlet of the stripping tower reboiler through a pipeline; the cold-side outlet of the stripping tower reboiler is connected to the two-phase inlet of the hydrogen-rich flash tank through a pipeline in sequence through the first hot-side inlet of the second heat exchanger and the first cold-side outlet of the second heat exchanger.

[0010] The hydrogen-rich gas outlet of the hydrogen-rich flash tank passes through the first cold-side inlet of the second heat exchanger, the first hot-side outlet of the second heat exchanger, the first cold-side inlet of the first heat exchanger, and the first hot-side outlet of the first heat exchanger in sequence via a pipeline before exiting the cold box and connecting to an external hydrogen-rich gas recovery device; the liquid phase outlet at the bottom of the hydrogen-rich flash tank is connected to the feed inlet of the stripping tower via a pipeline.

[0011] The flash steam outlet at the top of the stripping tower passes through the second cold-side inlet of the second heat exchanger, the second hot-side outlet of the second heat exchanger, the second cold-side inlet of the first heat exchanger, and the second hot-side outlet of the first heat exchanger in sequence via a pipeline before exiting the cold box and connecting to an external flash steam recovery device; the liquid phase outlet at the bottom of the stripping tower is connected to the feed inlet in the middle of the demethanizer tower via a pipeline.

[0012] The methane-rich gas outlet at the bottom of the demethanizer passes through a pipeline sequentially through the fourth cold-side inlet of the second heat exchanger, the fourth hot-side outlet of the second heat exchanger, the fourth cold-side inlet of the first heat exchanger, and the fourth hot-side outlet of the first heat exchanger before exiting the cold box and connecting to an external methane-rich gas recovery device. The gas phase outlet pipeline at the top of the demethanizer passes through the demethanizer condenser and connects to the top inlet of the demethanizer separator. The liquid phase outlet at the bottom of the demethanizer separator is divided into two branches: one branch connects to the feed inlet at the top of the demethanizer, and the other branch connects to the inlet of the CO liquid pump.

[0013] The outlet of the CO liquid pump is divided into two branches. One branch is connected to the inlet in the middle of the demethanizer separator, and the other branch passes through the third cold side inlet of the second heat exchanger, the third hot side outlet of the second heat exchanger, the third cold side inlet of the first heat exchanger, and the third hot side outlet of the first heat exchanger before exiting the cold box and connecting to the external high-pressure CO product recovery device.

[0014] Furthermore, a throttling valve is installed on the pipeline between the liquid phase outlet at the bottom of the hydrogen-rich flash tank and the feed inlet of the stripping tower.

[0015] Furthermore, a throttling valve is installed on the pipeline between the bottom liquid phase outlet of the stripping tower and the middle feed inlet of the demethanizing tower.

[0016] Furthermore, a pressure regulating valve is installed on the pipeline between the CO liquid pump outlet and the middle inlet of the demethanizer separator.

[0017] Furthermore, a flow regulating valve is installed on the pipeline between the third hot-side outlet of the first heat exchanger and the external high-pressure CO product recovery device.

[0018] Furthermore, the nitrogen cycle refrigeration is specifically as follows:

[0019] The final stage outlet of the nitrogen cycle compressor is connected to the second hot-side inlet of the first heat exchanger via a pipeline; the pipeline of the second cold-side outlet of the first heat exchanger is divided into two branches after passing through the demethanizer reboiler; one branch passes sequentially through the fifth cold-side inlet, the fifth hot-side outlet of the second heat exchanger, the fifth cold-side inlet and the fifth hot-side outlet of the first heat exchanger and then connects to the first stage inlet of the nitrogen cycle compressor; the other branch passes sequentially through the demethanizer condenser, the sixth cold-side inlet, the sixth hot-side outlet of the second heat exchanger, the sixth cold-side inlet and the sixth hot-side outlet of the first heat exchanger and then connects to the second stage inlet of the nitrogen cycle compressor, thus forming a nitrogen cycle refrigeration system;

[0020] The liquid nitrogen outlet of the liquid nitrogen replenishment device exits the cold box through a pipeline that passes sequentially through the seventh cold-side inlet of the second heat exchanger, the seventh hot-side outlet of the second heat exchanger, the seventh cold-side inlet of the first heat exchanger, and the seventh hot-side outlet of the first heat exchanger, thus providing supplemental cooling capacity to the cold box.

[0021] Furthermore, a throttling valve is provided on the pipe between the cold-side outlet of the demethanizer reboiler and the fifth cold-side inlet of the second heat exchanger.

[0022] Furthermore, a throttling valve is installed on the pipeline between the cold side outlet of the demethanizer reboiler and the demethanizer condenser.

[0023] Secondly, the present invention provides a method for preparing high-pressure CO using the nitrogen-throttling CO pump pressurized dehydrogenation and demethanization apparatus for preparing high-pressure CO as described in the first aspect, as follows:

[0024] The purified gas from upstream enters the first heat exchanger through a pipeline to cool down and then enters the stripping tower reboiler to provide heat for the stripping tower. After cooling down, the purified gas enters the hydrogen-rich flash tank for separation after being further cooled by the second heat exchanger.

[0025] The hydrogen-rich gas at the top of the hydrogen-rich flash tank is reheated by passing through the second heat exchanger and the first heat exchanger in sequence, and then exits the cold box as ambient temperature hydrogen-rich gas; the liquid phase at the bottom of the hydrogen-rich flash tank is throttled and then enters the stripping tower for dehydrogenation treatment.

[0026] The low-temperature flash steam at the top of the stripping tower is reheated by passing through the second heat exchanger and the first heat exchanger in sequence, and then exits the cold box as ambient temperature flash steam; the liquid phase at the bottom of the stripping tower is throttled and then enters the demethanizer for demethanization treatment.

[0027] The methane-rich gas at the bottom of the demethanizer passes through the second heat exchanger and the first heat exchanger in sequence to be reheated, and then exits the cold box as ambient temperature methane-rich gas; the gas phase at the top of the demethanizer enters the demethanizer condenser and is completely condensed before entering the demethanizer separator.

[0028] Part of the liquid phase at the bottom of the demethanizer separator is returned to the top of the demethanizer, and the other part is pressurized to the product pressure by the CO liquid pump and then reheated by the second heat exchanger and the first heat exchanger to obtain high-pressure CO product exiting the cold box.

[0029] The circulating nitrogen from the final stage outlet of the nitrogen cycle compressor is cooled by the first heat exchanger and then enters the reboiler of the demethanizer to provide heat for the demethanizer. The nitrogen flowing out from the cold side outlet of the demethanizer reboiler is partially throttled and then reheated by passing through the second and first heat exchangers before flowing back to the first stage inlet of the nitrogen cycle compressor. The other part is throttled and then enters the demethanizer condenser to provide cooling for the vapor phase condensation at the top of the demethanizer. After passing through the second and first heat exchangers and reheating, it flows back to the second stage inlet of the nitrogen cycle compressor, thus forming a nitrogen cycle refrigeration system.

[0030] Liquid nitrogen from the liquid nitrogen replenishment device is throttled and then reheated through the second and first heat exchangers before exiting the cold box, providing supplemental cooling capacity for the cold box.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] This invention optimizes the process flow of existing HyCO separation, dehydrogenation, and demethanization units by combining a nitrogen-cycle compressor with a CO liquid pump, replacing the traditional multi-stage CO compression system. This improved system utilizes the nitrogen-cycle compressor to condense the gaseous CO product from the top of the demethanization tower into a liquid phase in the condenser, providing the necessary cooling capacity to the cold box and achieving balance in the multi-stage heat exchange within the cold box. Simultaneously, the CO liquid pump directly pressurizes the condensed liquid CO product to the required high pressure, reheats it, and then sends it out of the cold box, thus obtaining a high-pressure CO product.

[0033] The improved unit effectively simplifies the complex structure of the original multi-stage CO compression system. In comparison, the nitrogen cycle compression system offers advantages such as high compression efficiency, a wide range of model options, short delivery cycles, and higher process safety levels, resulting in more stable and reliable operation. Furthermore, the CO liquid pump equipment is not only lower in cost, more compact in structure, and easier to maintain, but also, due to its lower investment cost, can be flexibly configured with one pump in operation and one on standby, thus ensuring continuous operation and convenient maintenance of the unit. Attached Figure Description

[0034] Figure 1 A schematic diagram of the process for a nitrogen-throttling CO pump pressurized dehydrogenation and demethanization device for producing high-pressure CO provided by the present invention;

[0035] Figure 2 This is a schematic diagram of the process for the high-pressure CO preparation unit using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethanization, as preferred in the embodiments.

[0036] Figure 3 This is a schematic diagram of nitrogen cycle refrigeration and liquid nitrogen replenishment in the embodiment;

[0037] Figure 4 This is a partial schematic diagram of the demethanizing device in the embodiment;

[0038] In the diagram: 1. First heat exchanger; 2. Second heat exchanger; 3. Stripper reboiler; 4. Hydrogen-rich flash tank; 5. Stripper; 6. Demethanizer; 7. Demethanizer reboiler; 8. Demethanizer condenser; 9. Demethanizer separator; 10. CO liquid pump; 11. Nitrogen cycle compressor. Detailed Implementation

[0039] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0040] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0041] In the description of this invention, it should be understood that the terms “low temperature”, “normal temperature”, “low pressure”, and “high pressure” refer to the temperature or pressure relative to the same medium in the same passage, and should not be construed as indicating or implying relative importance or implicitly specifying the temperature and pressure values ​​of the indicated technical features.

[0042] like Figure 1 As shown, in a preferred embodiment of the present invention, this embodiment provides a nitrogen-throttling CO pump pressurized dehydrogenation and demethanization apparatus for producing high-pressure CO. The apparatus includes a first heat exchanger 1, a second heat exchanger 2, a stripping tower reboiler 3, a hydrogen-rich flash tank 4, a stripping tower 5, a demethanization tower 6, a demethanization tower reboiler 7, a demethanization tower condenser 8, a demethanization tower separator 9, and a CO liquid pump 10, all housed within a cold box. It also includes a nitrogen circulation compressor 11 and a liquid nitrogen replenishment device located outside the cold box.

[0043] In the apparatus provided by this invention, purified gas from upstream passes sequentially through a first heat exchanger 1, a stripper reboiler 3, and a second heat exchanger 2 for cooling before entering a hydrogen-rich flash tank 4. The liquid phase at the bottom of the hydrogen-rich flash tank 4 enters a stripper 5 for further separation. The liquid phase at the bottom of the stripper 5 enters a demethanizer 6 for demethanization treatment. The gas phase at the top of the demethanizer 6 is completely condensed by a demethanizer condenser 8 and then enters a demethanizer separator 9. The liquid phase at the bottom of the demethanizer separator 9 is pressurized by a CO liquid pump 10 and then sequentially passes through a second heat exchanger 2 and a first heat exchanger 1 for reheating, resulting in high-pressure CO product exiting the cold box. Using a CO liquid pump 6 to pressurize the product while CO is in a liquid state replaces the conventional CO multi-stage circulating compressor for pressurizing the CO product, which can improve system compression efficiency, reduce equipment costs, simplify equipment complexity, and shorten the construction period.

[0044] The connection methods of the various components within the device provided in this embodiment are described in detail below:

[0045] In the apparatus provided in this embodiment, the first hot-side inlet of the first heat exchanger 1 receives purified gas from upstream. It should be noted that the upstream purified gas generally refers to synthesis gas whose main components are H2 and CO, and also contains small amounts of impurities such as nitrogen and methane. The first cold-side outlet of the first heat exchanger 1 is connected to the hot-side inlet of the stripping tower reboiler 3 via a pipeline. The cold-side outlet of the stripping tower reboiler 3 is connected to the two-phase inlet of the hydrogen-rich flash tank 4 via a pipeline, passing sequentially through the first hot-side inlet and the first cold-side outlet of the second heat exchanger 2.

[0046] In the device provided in this embodiment, the hydrogen-rich gas outlet of the hydrogen-rich flash tank 4 passes through the first cold-side inlet of the second heat exchanger 2, the first hot-side outlet of the second heat exchanger 2, the first cold-side inlet of the first heat exchanger 1, and the first hot-side outlet of the first heat exchanger 1 in sequence via a pipeline, and then exits the cold box and is connected to the external hydrogen-rich gas recovery device.

[0047] In the apparatus provided in this embodiment, the liquid phase outlet at the bottom of the hydrogen-rich flash tank 4 is connected to the feed inlet of the stripping tower 5 via a pipe equipped with a throttling valve. The flash vapor outlet at the top of the stripping tower 5 passes through a pipe sequentially through the second cold-side inlet of the second heat exchanger 2, the second hot-side outlet of the second heat exchanger 2, the second cold-side inlet of the first heat exchanger 1, and the second hot-side outlet of the first heat exchanger 1 before exiting the cold box and connecting to an external flash vapor recovery device.

[0048] In the apparatus provided in this embodiment, the liquid phase outlet at the bottom of the stripping tower 5 is connected to the feed inlet in the middle of the demethanizer 6 via a pipe equipped with a throttling valve. The methane-rich gas outlet at the bottom of the demethanizer 6 passes through the fourth cold-side inlet of the second heat exchanger 2, the fourth hot-side outlet of the second heat exchanger 2, the fourth cold-side inlet of the first heat exchanger 1, and the fourth hot-side outlet of the first heat exchanger 1 in sequence via a pipe before exiting the cold box and connecting to an external methane-rich gas recovery device.

[0049] In the device provided in this embodiment, such as Figure 4 As shown, the gas phase outlet pipe at the top of the demethanizer 6 connects to the top inlet of the demethanizer separator 9 after passing through the demethanizer condenser 8. The liquid phase outlet at the bottom of the demethanizer separator 9 is divided into two branches: one branch connects to the feed inlet at the top of the demethanizer 6, and the other branch connects to the inlet of the CO liquid pump 10. The outlet of the CO liquid pump 10 is divided into two branches: one branch connects to the inlet in the middle of the demethanizer separator 9, and the other branch passes sequentially through the third cold-side inlet of the second heat exchanger 2, the third hot-side outlet of the second heat exchanger 2, the third cold-side inlet of the first heat exchanger 1, and the third hot-side outlet of the first heat exchanger 1 before exiting the cold box and connecting to the external high-pressure CO product recovery device. It should be noted that, as a preferred embodiment, a pressure regulating valve is provided on the pipe between the outlet of the CO liquid pump 10 and the inlet in the middle of the demethanizer separator 9 to indicate and control the pressure of the CO gas. A flow regulating valve is installed on the pipeline connecting the third hot-side outlet of the first heat exchanger 1 to the external high-pressure CO product recovery device to indicate and control the flow rate of the high-pressure CO product gas, specifically as follows: Figure 2 As shown.

[0050] In the apparatus provided in this embodiment, nitrogen from the nitrogen cycle compressor 11 provides nitrogen cycle refrigeration for the cold box, and liquid nitrogen from the liquid nitrogen replenishment device provides supplementary cooling capacity for the cold box. Figure 3 As shown, the specific connection method is as follows:

[0051] The final stage outlet of the nitrogen cycle compressor 11 is connected to the second hot-side inlet of the first heat exchanger 1 via a pipeline. The pipeline from the second cold-side outlet of the first heat exchanger 1 branches into two branches after passing through the demethanizer reboiler 7. One branch passes sequentially through the fifth cold-side inlet, the fifth hot-side outlet of the second heat exchanger 2, the fifth cold-side inlet, and the fifth hot-side outlet of the first heat exchanger 1 before connecting to the first-stage inlet of the nitrogen cycle compressor 11. In this embodiment, a throttling valve is installed on the pipeline between the cold-side outlet of the demethanizer reboiler 7 and the fifth cold-side inlet of the second heat exchanger 2.

[0052] Another branch sequentially passes through the demethanizer condenser 8, the sixth cold-side inlet of the second heat exchanger 2, the sixth hot-side outlet of the second heat exchanger 2, the sixth cold-side inlet of the first heat exchanger 1, and the sixth hot-side outlet of the first heat exchanger 1 before connecting to the secondary air inlet of the nitrogen cycle compressor 11, thus forming a nitrogen cycle refrigeration system. In this embodiment, a throttling valve is installed on the pipeline between the cold-side outlet of the demethanizer reboiler 7 and the demethanizer condenser 8.

[0053] The liquid nitrogen outlet of the liquid nitrogen replenishment device passes through the seventh cold-side inlet of the second heat exchanger 2, the seventh hot-side outlet of the second heat exchanger 2, the seventh cold-side inlet of the first heat exchanger 1, and the seventh hot-side outlet of the first heat exchanger 1 in sequence through a pipeline before exiting the cold box, providing supplemental cooling capacity to the cold box.

[0054] This embodiment also provides a method for preparing high-pressure CO using the above-described apparatus, as follows:

[0055] (1) Pre-cooling and preliminary separation of purified gas

[0056] Purified gas (mainly CO and H2) from upstream enters the first heat exchanger 1 through a pipeline for cooling. The cooled purified gas then enters the stripping tower reboiler 3, serving as a heat source to provide heat to the bottom of the stripping tower 5, while being further cooled itself. Subsequently, the purified gas enters the second heat exchanger 2 for further cooling before entering the hydrogen-rich flash tank 4 for gas-liquid separation.

[0057] (2) Hydrogen separation and stripping dehydrogenation

[0058] In the hydrogen-rich flash tank 4, the hydrogen-rich gas at the top is reheated by passing through the second heat exchanger 2 and the first heat exchanger 1, resulting in ambient temperature hydrogen-rich gas exiting the cold box as the hydrogen-rich product. The liquid phase at the bottom of the hydrogen-rich flash tank 4 enters the stripping tower 5 after throttling. Inside the stripping tower 5, the rising gas desorbs most of the dissolved hydrogen from the liquid phase, performing dehydrogenation treatment.

[0059] The low-temperature flash vapor at the top of stripper 5 is reheated by passing through the second heat exchanger 2 and the first heat exchanger 1 in sequence, and then exits the cold box as ambient temperature flash vapor, which is output as the flash vapor product. The liquid phase at the bottom of stripper 5 enters the subsequent demethanization process.

[0060] (3) Demethanization distillation and high-pressure CO product preparation

[0061] The liquid phase at the bottom of stripping tower 5 is throttled and then enters demethanizing tower 6 for demethanization treatment. The methane-rich gas at the bottom of demethanizing tower 6 is then reheated by passing through the second heat exchanger 2 and the first heat exchanger 1 in sequence, and then exits the cold box as ambient temperature methane-rich gas, which is output as the methane-rich gas product.

[0062] The gas phase at the top of the demethanizer 6 enters the demethanizer condenser 8, where the low-temperature nitrogen gas, after being throttled, is completely condensed into liquid and then enters the demethanizer separator 9. Part of the liquid phase at the bottom of the demethanizer separator 9 flows back to the top of the demethanizer 6, while the other part is pressurized to the product pressure by the CO liquid pump 10 and then reheated by the second heat exchanger 2 and the first heat exchanger 1 to obtain the high-pressure CO product exiting the cold box, thus obtaining the final high-pressure CO product.

[0063] (4) Nitrogen circulation refrigeration

[0064] The circulating nitrogen from the final stage outlet of the nitrogen cycle compressor 11 is cooled by the first heat exchanger 1 and then enters the demethanizer reboiler 7 to provide heat for the demethanizer 6. The nitrogen flowing out from the cold side outlet of the demethanizer reboiler 7 is partially throttled and then reheated by passing through the second heat exchanger 2 and the first heat exchanger 1 before flowing back to the first stage inlet of the nitrogen cycle compressor 11. The other part is throttled and then enters the demethanizer condenser 8 to provide cooling for the vapor phase condensation at the top of the demethanizer 6. After passing through the second heat exchanger 2 and the first heat exchanger 1 in sequence, it is reheated and then flows back to the second stage inlet of the nitrogen cycle compressor 11, thus forming a nitrogen cycle refrigeration system.

[0065] This embodiment also includes a liquid nitrogen replenishment device. After being throttled, the liquid nitrogen from the liquid nitrogen replenishment device passes through the second heat exchanger 2 and the first heat exchanger 1 in sequence to be reheated before exiting the cold box, thus providing supplemental cooling capacity to the cold box.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A nitrogen-throttling CO pump pressurized dehydrogenation and demethanization apparatus for producing high-pressure CO, characterized in that, It includes a first heat exchanger (1), a second heat exchanger (2), a stripping tower reboiler (3), a hydrogen-rich flash tank (4), a stripping tower (5), a demethanizer (6), a demethanizer reboiler (7), a demethanizer condenser (8), a demethanizer separator (9), and a CO liquid pump (10) installed inside the cold box, as well as a nitrogen circulation compressor (11) and a liquid nitrogen replenishment device outside the cold box; The purified gas from upstream passes through the first heat exchanger (1), the stripper reboiler (3), and the second heat exchanger (2) in sequence to cool down before entering the hydrogen-rich flash tank (4); the liquid phase at the bottom of the hydrogen-rich flash tank (4) enters the stripper (5) for further separation; the liquid phase at the bottom of the stripper (5) enters the demethanizer (6) for demethanization treatment; the gas phase at the top of the demethanizer (6) is completely condensed by the demethanizer condenser (8) and then enters the demethanizer separator (9); the liquid phase at the bottom of the demethanizer separator (9) is pressurized by the CO liquid pump (10) and then passes through the second heat exchanger (2) and the first heat exchanger (1) in sequence for reheating to obtain high-pressure CO product exiting the cold box; nitrogen from the nitrogen cycle compressor (11) provides nitrogen cycle refrigeration for the cold box, and liquid nitrogen from the liquid nitrogen replenishment device provides supplementary cooling capacity for the cold box.

2. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethane removal according to claim 1, characterized in that, The specific structure is as follows: The first hot side inlet of the first heat exchanger (1) receives purified gas from upstream, and the first cold side outlet of the first heat exchanger (1) is connected to the hot side inlet of the stripping tower reboiler (3) through a pipeline; the cold side outlet of the stripping tower reboiler (3) is connected to the two-phase inlet of the hydrogen-rich flash tank (4) through a pipeline, passing sequentially through the first hot side inlet of the second heat exchanger (2) and the first cold side outlet of the second heat exchanger (2); The hydrogen-rich flash tank (4) has its hydrogen-rich outlet passing through the first cold-side inlet of the second heat exchanger (2), the first hot-side outlet of the second heat exchanger (2), the first cold-side inlet of the first heat exchanger (1), and the first hot-side outlet of the first heat exchanger (1) before exiting the cold box and connecting to an external hydrogen-rich recovery device. The liquid phase outlet at the bottom of the hydrogen-rich flash tank (4) is connected to the feed inlet of the stripping tower (5) through a pipeline. The flash steam outlet at the top of the stripping tower (5) passes through the second cold side inlet of the second heat exchanger (2), the second hot side outlet of the second heat exchanger (2), the second cold side inlet of the first heat exchanger (1), and the second hot side outlet of the first heat exchanger (1) in sequence via a pipeline before exiting the cold box and connecting to the flash steam recovery device in the outside; the liquid phase outlet at the bottom of the stripping tower (5) is connected to the feed port in the middle of the demethanizer tower (6) via a pipeline; The methane-rich gas outlet at the bottom of the demethanizer (6) passes through the fourth cold-side inlet of the second heat exchanger (2), the fourth hot-side outlet of the second heat exchanger (2), the fourth cold-side inlet of the first heat exchanger (1), and the fourth hot-side outlet of the first heat exchanger (1) before exiting the cold box and connecting to the external methane-rich gas recovery device. The gas phase outlet pipe at the top of the demethanizer (6) passes through the demethanizer condenser (8) and connects to the top inlet of the demethanizer separator (9). The liquid phase outlet at the bottom of the demethanizer separator (9) is divided into two branches, one branch connecting to the feed inlet at the top of the demethanizer (6), and the other branch connecting to the inlet of the CO liquid pump (10). The outlet of the CO liquid pump (10) is divided into two branches. One branch is connected to the inlet in the middle of the demethanizer separator (9). The other branch passes through the third cold side inlet of the second heat exchanger (2), the third hot side outlet of the second heat exchanger (2), the third cold side inlet of the first heat exchanger (1), and the third hot side outlet of the first heat exchanger (1) before exiting the cold box and connecting with the external high-pressure CO product recovery device.

3. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethanization according to claim 2, characterized in that, A throttling valve is installed on the pipeline between the bottom liquid phase outlet of the hydrogen-rich flash tank (4) and the feed inlet of the stripping tower (5).

4. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethane removal according to claim 2, characterized in that, A throttling valve is installed on the pipeline between the bottom liquid outlet of the stripping tower (5) and the middle feed inlet of the demethanizer tower (6).

5. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethane removal according to claim 2, characterized in that, A pressure regulating valve is provided on the pipeline between the outlet of the CO liquid pump (10) and the middle inlet of the demethanizer separator (9).

6. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethanization according to claim 2, characterized in that, A flow regulating valve is installed on the pipeline between the third hot side outlet of the first heat exchanger (1) and the external high-pressure CO product recovery device.

7. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethanization according to claim 2, characterized in that, The nitrogen cycle refrigeration is described in the following details: The final stage outlet of the nitrogen cycle compressor (11) is connected to the second hot side inlet of the first heat exchanger (1) via a pipeline; the pipeline of the second cold side outlet of the first heat exchanger (1) is divided into two branches after passing through the demethanizer reboiler (7); one branch passes through the fifth cold side inlet of the second heat exchanger (2), the fifth hot side outlet of the second heat exchanger (2), the fifth cold side inlet of the first heat exchanger (1) and the fifth hot side outlet of the first heat exchanger (1) in sequence and then connects to the first stage inlet of the nitrogen cycle compressor (11); the other branch passes through the demethanizer condenser (8), the sixth cold side inlet of the second heat exchanger (2), the sixth hot side outlet of the second heat exchanger (2), the sixth cold side inlet of the first heat exchanger (1) and the sixth hot side outlet of the first heat exchanger (1) in sequence and then connects to the second stage inlet of the nitrogen cycle compressor (11), thus forming a nitrogen cycle refrigeration; The liquid nitrogen outlet of the liquid nitrogen replenishment device passes through the seventh cold side inlet of the second heat exchanger (2), the seventh hot side outlet of the second heat exchanger (2), the seventh cold side inlet of the first heat exchanger (1), and the seventh hot side outlet of the first heat exchanger (1) in sequence through a pipeline before exiting the cold box to provide supplemental cooling capacity to the cold box.

8. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethanization according to claim 7, characterized in that, A throttling valve is provided on the pipe between the cold side outlet of the demethanizer reboiler (7) and the fifth cold side inlet of the second heat exchanger (2).

9. The high-pressure CO preparation apparatus using a nitrogen-throttling CO pump for pressurized dehydrogenation and demethanization according to claim 7, characterized in that, A throttling valve is provided on the pipeline between the cold side outlet of the demethanizer reboiler (7) and the demethanizer condenser (8).

10. A method for preparing high-pressure CO using a nitrogen-throttling CO pump pressurized for dehydrogenation and demethanization as described in any one of claims 1 to 9, characterized in that, Specifically as follows: The purified gas from upstream enters the first heat exchanger (1) through a pipeline to cool down and then enters the stripping tower reboiler (3) to provide heat for the stripping tower (5); the cooled purified gas enters the hydrogen-rich flash tank (4) for separation after being further cooled by the second heat exchanger (2). The hydrogen-rich gas at the top of the hydrogen-rich flash tank (4) is reheated by passing through the second heat exchanger (2) and the first heat exchanger (1) in sequence, and then the ambient temperature hydrogen-rich gas exits the cold box; the liquid phase at the bottom of the hydrogen-rich flash tank (4) is throttled and then enters the stripping tower (5) for dehydrogenation treatment. The low-temperature flash steam at the top of the stripping tower (5) is reheated by passing through the second heat exchanger (2) and the first heat exchanger (1) in sequence, and then exits the cold box as ambient temperature flash steam; the liquid phase at the bottom of the stripping tower (5) is throttled and then enters the demethanizing tower (6) for demethanizing treatment. The methane-rich gas at the bottom of the demethanizer (6) is reheated by passing through the second heat exchanger (2) and the first heat exchanger (1) in sequence, and then exits the cold box as ambient temperature methane-rich gas; the gas phase at the top of the demethanizer (6) enters the demethanizer condenser (8) and is completely condensed before entering the demethanizer separator (9). A portion of the liquid phase at the bottom of the demethanizer separator (9) is returned to the top of the demethanizer (6), and the other portion is pressurized to the product pressure by the CO liquid pump (10) and then reheated by the second heat exchanger (2) and the first heat exchanger (1) to obtain high-pressure CO product exiting the cold box. The circulating nitrogen from the final stage outlet of the nitrogen cycle compressor (11) is cooled by the first heat exchanger (1) and then enters the demethanizer reboiler (7) to provide heat for the demethanizer (6). The nitrogen flowing out from the cold side outlet of the demethanizer reboiler (7) is partially throttled and then reheated by the second heat exchanger (2) and the first heat exchanger (1) before flowing back to the first stage inlet of the nitrogen cycle compressor (11). The other part is throttled and then enters the demethanizer condenser (8) to provide cooling for the vapor phase condensation at the top of the demethanizer (6). After that, it is reheated by the second heat exchanger (2) and the first heat exchanger (1) before flowing back to the second stage inlet of the nitrogen cycle compressor (11), thus forming a nitrogen cycle refrigeration. After being throttled, the liquid nitrogen from the liquid nitrogen replenishment device passes through the second heat exchanger (2) and the first heat exchanger (1) in sequence to be reheated before exiting the cold box, providing supplemental cooling capacity for the cold box.

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