Hydrogen production system and method for producing hydrogen

Abstract

This invention discloses an integrated system for cryogenic separation and hydrogen liquefaction of HyCO syngas, belonging to the field of refrigeration and cryogenic engineering technology. HyCO syngas from upstream purification is pre-cooled in a pre-cooling unit and then enters a distillation column in the HyCO separation unit for component separation. The separated CO is reheated and exits the cold box as CO product gas, while hydrogen enters a cryogenic adsorption unit for purification. The purified hydrogen is further cooled in the cryogenic unit using a hydrogen-Claude cycle, and after throttling to the liquefaction temperature, the gaseous hydrogen and part of the liquid hydrogen are reheated, compressed, and recirculated. The remaining liquid hydrogen enters a liquid hydrogen storage tank as product. This integrated system can simultaneously separate HyCO syngas and produce liquid hydrogen with a secondary hydrogen content of not less than 98%, suitable for a scale of 50-100 tons of liquid hydrogen / day, with a specific energy consumption of no more than 6.8 kWh / kg liquid hydrogen. This integrated system efficiently couples two independent processes, solving the problem of high energy consumption in cryogenic separation of HyCO and hydrogen liquefaction, and significantly reducing the cost of CO and liquid hydrogen co-production.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration and cryogenic engineering technology, specifically relating to an integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas. Background Technology

[0002] HyCO syngas is a mixture of hydrogen and carbon monoxide (CO). Industrially, cryogenic separation is the most important method for separating and purifying HyCO syngas. The principle involves cooling the mixture to a certain temperature and then separating the components within a distillation column based on their boiling point differences. During cryogenic separation, the hydrogen component in the feed gas undergoes cooling and reheating, increasing the degree of thermodynamic irreversibility. Furthermore, due to the limitation of the refrigeration temperature, the purity of the hydrogen at the top of the distillation column cannot meet the requirements for hydrogen liquefaction of the feed gas.

[0003] Currently, cryogenic separation of HyCO and hydrogen liquefaction are typically two independent processes, built in separate plants. Based on hydrogen gas, the energy consumption for cryogenic separation of HyCO is ~0.7 kWh / kg hydrogen, while that for hydrogen liquefaction is ~12 kWh / kg liquid hydrogen. The total energy consumption of both processes is relatively high. However, these two processes actually have an inherent need for combined production and energy-saving potential. On the one hand, HyCO hydrogen production aligns with my country's energy structure characteristics, and its production cost is far lower than that of hydrogen produced by water electrolysis. The separated CO can be used in downstream synthesis processes to achieve zero carbon emissions. On the other hand, from a refrigeration perspective, the two processes have a significant overlap in their refrigeration temperature ranges. Optimizing the cryogenic separation process of HyCO to produce high-purity, low-temperature hydrogen can be directly used as feedstock for hydrogen liquefaction. Therefore, integrating and optimizing the two processes can not only simplify the process and reduce equipment, but also solve the high energy consumption problem of cryogenic separation of HyCO syngas and hydrogen liquefaction production, showing broad application prospects.

[0004] However, there is currently no research on integrated systems for cryogenic separation of HyCO syngas and hydrogen liquefaction. How to rationally and efficiently combine the two processes to simultaneously meet the requirements of CO and liquid hydrogen products and reduce the energy consumption of the integrated system is an important problem that urgently needs to be solved in the design of integrated systems for cryogenic separation of HyCO syngas and hydrogen liquefaction. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides an integrated system for cryogenic separation and hydrogen liquefaction of HyCO syngas. This system directly uses the high-purity, low-temperature hydrogen generated during cryogenic separation as the feed gas for hydrogen liquefaction and employs a hydrogen-Claude cycle refrigeration process to achieve efficient integration of cryogenic separation and hydrogen liquefaction of HyCO syngas. This simplifies the process, reduces energy consumption, and saves on project land and equipment investment. Based on liquid hydrogen, the specific energy consumption of the entire integrated system is less than 6.8 kWh / kg liquid hydrogen.

[0006] To achieve the above effects, the specific technical solution adopted by the present invention is as follows:

[0007] This invention provides an integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas. The integrated system includes a precooling unit, a HyCO separation unit, a cryogenic adsorption unit, a cryogenic unit, and a liquefaction unit. The precooling unit includes a primary heat exchanger, a secondary heat exchanger, and a hydrogen compressor unit. The HyCO separation unit includes a reboiler, a distillation column, and a condenser. The cryogenic adsorption unit includes a cryogenic adsorption system. The cryogenic unit includes a tertiary heat exchanger, a quaternary heat exchanger, a primary hydrogen expander, and a secondary hydrogen expander. The liquefaction unit includes a quinary heat exchanger, a hydrogen separator, and a liquid hydrogen storage tank.

[0008] HyCO synthesis gas from upstream purification enters the precooling unit. After precooling, it enters the distillation column in the HyCO separation unit for separation, yielding carbon monoxide product gas and hydrogen. The hydrogen is then purified by the cryogenic adsorption unit before entering the cryogenic unit. Part of the cryogenic hydrogen separated in the cryogenic unit provides cooling for the precooling unit, while the other part enters the liquefaction unit to produce liquid hydrogen.

[0009] Preferably, the HyCO synthesis gas from upstream purification is connected to the first hot-side inlet of the first-stage heat exchanger via a first pipe. The first hot-side outlet of the first-stage heat exchanger is connected to the hot-side inlet of the reboiler via a second pipe. The hot-side outlet of the reboiler is connected to the first hot-side inlet of the second-stage heat exchanger via a third pipe. A pre-cooling cycle is also provided between the first-stage and second-stage heat exchangers.

[0010] The first hot-side outlet of the secondary heat exchanger is connected to the central inlet of the distillation column via a fourth pipe. The bottom of the distillation column has a first liquid outlet and a second liquid outlet. The first liquid outlet at the bottom of the distillation column returns to the bottom of the distillation column after passing through a fifth pipe, the cold-side inlet of the reboiler, the cold-side outlet of the reboiler, and a sixth pipe. The second liquid outlet at the bottom of the distillation column is connected to the carbon monoxide inlet of the secondary heat exchanger via a first carbon monoxide pipe and a second carbon monoxide pipe. The carbon monoxide outlet of the secondary heat exchanger is connected to the carbon monoxide inlet of the primary heat exchanger via a third carbon monoxide pipe. The carbon monoxide product gas is discharged from the primary heat exchanger via a fourth carbon monoxide pipe.

[0011] The distillation column has a gas outlet at the top, which is connected to the gas inlet of the condenser via a seventh pipe. The liquid outlet of the condenser is connected to the top of the distillation column via an eighth pipe. The gas outlet of the condenser is connected to the inlet of the cryogenic adsorption system via a ninth pipe. The hydrogen outlet of the cryogenic adsorption system is connected to the inlet of the first hydrogen pipe.

[0012] The second hot-side inlet of the first-stage heat exchanger is connected to the outlet of the hydrogen compressor unit via the second hydrogen pipeline. The second hot-side outlet of the first-stage heat exchanger is connected to the second hot-side inlet of the second-stage heat exchanger via the third hydrogen pipeline. The second hot-side outlet of the second-stage heat exchanger has two branches: one branch connects to the hot-side inlet of the third-stage heat exchanger via the fourth hydrogen pipeline, and the other branch connects to the inlet of the first-stage hydrogen expander unit via the fifth hydrogen pipeline. The outlet of the first-stage hydrogen expander unit is connected to the inlet of the eighth hydrogen pipeline.

[0013] The hot-side outlet of the third-stage heat exchanger is connected to the inlet of the sixth hydrogen pipeline. The outlets of the sixth and first hydrogen pipelines merge at the inlet of the eleventh hydrogen pipeline. The outlet of the eleventh hydrogen pipeline has two branches: one branch connects to the inlet of the second-stage hydrogen expander via the ninth hydrogen pipeline, and the other branch connects to the hot-side inlet of the fourth-stage heat exchanger. The outlet of the second-stage hydrogen expander is connected to the inlet of the tenth hydrogen pipeline.

[0014] The hot-side outlet of the fourth-stage heat exchanger connects sequentially to the hot-side inlet of the fifth-stage heat exchanger via hydrogen pipelines twelfth and thirteenth. The hot-side outlet of the fifth-stage heat exchanger connects sequentially to the inlet of the hydrogen separator via hydrogen pipelines fourteenth and fifteenth. The hydrogen separator has a gas outlet at the top and a first liquid outlet and a second liquid outlet at the bottom. The gas outlet at the top of the hydrogen separator connects to the inlet of hydrogen pipeline seventeen, and the first liquid outlet at the bottom of the hydrogen separator connects to the inlet of hydrogen pipeline sixteen. The outlet of hydrogen pipeline seventeen merges with hydrogen pipeline sixteen and connects to the cold-side inlet of the fifth-stage heat exchanger. The second liquid outlet at the bottom of the hydrogen separator connects to the liquid hydrogen storage tank.

[0015] The cold-side outlet of the fifth-stage heat exchanger connects to the inlet of hydrogen pipeline number eighteen. The outlet of hydrogen pipeline number ten merges with hydrogen pipeline number eighteen and connects to the cold-side inlet of the fourth-stage heat exchanger. The cold-side outlet of the fourth-stage heat exchanger connects to the inlet of hydrogen pipeline number nineteen. The outlet of hydrogen pipeline number eight merges with hydrogen pipeline number nineteen and connects to the cold-side inlet of the condenser. The cold-side outlet of the condenser connects to the cold-side inlet of the third-stage heat exchanger via hydrogen pipeline number twenty. The cold-side outlet of the third-stage heat exchanger connects to the first cold-side inlet of the second-stage heat exchanger via hydrogen pipeline number twenty-one. The first cold-side outlet of the second-stage heat exchanger connects to the first cold-side inlet of the first-stage heat exchanger via pipeline number twenty-two. The first cold-side outlet of the first-stage heat exchanger connects to the inlet of the hydrogen compressor unit via pipeline number twenty-three, and the outlet of the hydrogen compressor unit connects to the second hot-side inlet of the first-stage heat exchanger via hydrogen pipeline number two, forming a hydrogen Claude cycle.

[0016] Furthermore, a carbon monoxide throttling valve is provided between the aforementioned first carbon monoxide pipe and second carbon monoxide pipe.

[0017] Furthermore, a first-stage hydrogen throttling valve is installed between the aforementioned hydrogen twelfth and hydrogen thirteenth pipelines.

[0018] Furthermore, a two-stage hydrogen throttling valve is installed between the aforementioned hydrogen pipeline fourteen and hydrogen pipeline fifteen.

[0019] Furthermore, the above precooling cycle employs liquid nitrogen refrigeration, nitrogen cycle refrigeration, or mixed refrigerant refrigeration technology.

[0020] Furthermore, the aforementioned primary heat exchanger, reboiler, secondary heat exchanger, tertiary heat exchanger, condenser, quaternary heat exchanger, and quinary heat exchanger are all aluminum plate-fin heat exchangers. Among them, the product channels of the quaternary and quinary heat exchangers are filled with corresponding catalytic performance of the secondary hydrogen conversion catalyst according to the refrigeration temperature zone.

[0021] Furthermore, the aforementioned low-temperature adsorption system is a temperature-switching adsorption system, and the adsorption tower is filled with molecular sieves or activated carbon to remove impurities that are easily frozen during the cooling process.

[0022] Furthermore, the aforementioned primary heat exchanger, reboiler, and secondary heat exchanger are housed in an ambient temperature cold box. The distillation column, cryogenic adsorption system, tertiary heat exchanger, primary hydrogen expander, condenser, secondary hydrogen expander, quaternary heat exchanger, quinary heat exchanger, and hydrogen separator are housed in a vacuum cold box.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The integrated system provided by the present invention uses the high-purity low-temperature hydrogen generated during the cryogenic separation of HyCO directly as the raw material gas for hydrogen liquefaction through optimized design, and adopts a single-pressure hydrogen Claude cycle refrigeration process to reduce the thermodynamic irreversibility of the two independent systems.

[0025] (2) The refrigerant in the integrated system provided by the present invention comes from hydrogen separated from HyCO synthesis gas. The hydrogen / hydrogen heat exchange process is simple, the heat exchange temperature difference is small, and the heat exchange efficiency is greatly improved.

[0026] (3) The integrated system provided by the present invention highly couples the HyCO synthesis gas cryogenic separation process and the hydrogen liquefaction process, reducing the number of cold boxes. The integrated system has a compact structure and simplified equipment, saving the initial investment and land area of ​​the project.

[0027] (4) According to the experiment, the integrated system provided by the present invention can achieve the separation of HyCO syngas and the production of liquid hydrogen with a secondary hydrogen content of not less than 98%, which is suitable for a scale of 50 to 100 tons of liquid hydrogen / day. The specific energy consumption of the system is no more than 6.8 kWh / kg liquid hydrogen, which is nearly half of the total energy consumption of the two independent processes. It solves the problem of high energy consumption of HyCO cryogenic separation and hydrogen liquefaction, and significantly reduces the cost of joint production of CO and liquid hydrogen. Attached Figure Description

[0028] Figure 1 A schematic diagram of the HyCO synthesis gas cryogenic separation and hydrogen liquefaction integrated system provided in the example;

[0029] In the diagram: First-stage heat exchanger HE1, reboiler HE2, second-stage heat exchanger HE3, third-stage heat exchanger HE4, condenser HE5, fourth-stage heat exchanger HE6, fifth-stage heat exchanger HE7, hydrogen compressor unit K1, distillation column T1, cryogenic adsorption system T2, first-stage hydrogen expander E1, second-stage hydrogen expander E2, carbon monoxide throttling valve V1, first-stage hydrogen throttling valve V2, second-stage hydrogen throttling valve V3, hydrogen separator D1, first pipeline F1, second pipeline F2, third pipeline F3, fourth pipeline F4, fifth pipeline F5, sixth pipeline F6, seventh pipeline F7, eighth pipeline F8, ninth pipeline F9, first carbon monoxide pipeline C1, second carbon monoxide pipeline C2, ... Carbon monoxide third pipe C3, carbon monoxide fourth pipe C4, hydrogen first pipe H1, hydrogen second pipe H2, hydrogen third pipe H3, hydrogen fourth pipe H4, hydrogen fifth pipe H5, hydrogen sixth pipe H6, hydrogen eighth pipe H8, hydrogen ninth pipe H9, hydrogen tenth pipe H10, hydrogen eleventh pipe H11, hydrogen twelfth pipe H12, hydrogen thirteenth pipe H13, hydrogen fourteenth pipe H14, hydrogen fifteenth pipe H15, hydrogen sixteenth pipe H16, hydrogen seventeenth pipe H17, hydrogen eighteenth pipe H18, hydrogen nineteenth pipe H19, hydrogen twentieth pipe H20, hydrogen twenty-first pipe H21, hydrogen twenty-second pipe H22, hydrogen twenty-third pipe H23. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0031] 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 as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0032] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0033] like Figure 1 As shown, this embodiment, as a preferred embodiment of a specific implementation, provides an integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas. The integrated system includes a precooling unit, a HyCO separation unit, a low-temperature adsorption unit, a cryogenic unit, a liquefaction unit, a feed gas pipeline, a carbon monoxide pipeline, and a hydrogen pipeline.

[0034] The precooling unit includes a primary heat exchanger HE1, a secondary heat exchanger HE3, a hydrogen compressor unit K1, and a precooling cycle. The HyCO separation unit includes a reboiler HE2, a distillation column T1, a carbon monoxide throttling valve V1, and a condenser HE5. The cryogenic adsorption unit includes a cryogenic adsorption system T2. The cryogenic unit includes a tertiary heat exchanger HE4, a quaternary heat exchanger HE6, a primary hydrogen expander unit E1, a secondary hydrogen expander unit E2, and a primary hydrogen throttling valve V2. The liquefaction unit includes a quinary heat exchanger HE7, a secondary hydrogen throttling valve V3, a hydrogen separator D1, and a liquid hydrogen storage tank.

[0035] HyCO synthesis gas from upstream purification enters the precooling unit. After precooling, it enters the distillation column T1 in the HyCO separation unit for separation, yielding carbon monoxide product gas and hydrogen. The hydrogen is then purified by the cryogenic adsorption unit before entering the cryogenic unit. Part of the cryogenic hydrogen separated in the cryogenic unit provides cooling for the precooling unit, while the other part enters the liquefaction unit to produce liquid hydrogen.

[0036] The specific structure of the integrated system provided in this embodiment is as follows:

[0037] HyCO synthesis gas from upstream purification is connected to the first hot-side inlet of primary heat exchanger HE1 via first pipe F1. The first hot-side outlet of primary heat exchanger HE1 is connected to the hot-side inlet of reboiler HE2 via second pipe F2. The hot-side outlet of reboiler HE2 is connected to the first hot-side inlet of secondary heat exchanger HE3 via third pipe F3. A pre-cooling cycle is also provided between primary heat exchanger HE1 and secondary heat exchanger HE3.

[0038] It should be noted that the precooling cycle can employ methods including but not limited to liquid nitrogen refrigeration, nitrogen cycle refrigeration, or mixed refrigerant refrigeration cycle.

[0039] HyCO synthesis gas is separated in distillation column T1. Distillation column T1 has an inlet in the middle and a first liquid outlet and a second liquid outlet at the bottom, forming two branches. The first liquid outlet at the bottom of distillation column T1 is connected to the cold-side inlet of reboiler HE2 via pipe F5 (fifth pipe). The cold-side outlet of reboiler HE2 is connected to the bottom of distillation column T1 via pipe F6 (sixth pipe), forming a loop. The second liquid outlet at the bottom of distillation column T1 is connected to the carbon monoxide inlet of secondary heat exchanger HE3 via carbon monoxide pipes C1 and C2 (first and second pipes). A carbon monoxide throttling valve V1 is installed between carbon monoxide pipes C1 and C2. The carbon monoxide outlet of secondary heat exchanger HE3 is connected to the carbon monoxide inlet of primary heat exchanger HE1 via carbon monoxide pipe C3 (third pipe). After reheating in primary heat exchanger HE1, the carbon monoxide exits the carbon monoxide outlet of primary heat exchanger HE1 via carbon monoxide pipe C4 (fourth pipe), yielding carbon monoxide product gas, which is then discharged from the cold box.

[0040] The distillation column T1 has a gas outlet at the top, which is connected to the gas inlet of the condenser HE5 via the seventh pipe F7. The liquid outlet of the condenser HE5 is connected to the top of the distillation column T1 via the eighth pipe F8, and the gas outlet of the condenser HE5 is connected to the inlet of the low-temperature adsorption system T2 via the ninth pipe F9. This allows the condensed liquid phase in the condenser to return to the top of the distillation column T1 via the eighth pipe F8, while the uncondensed gas phase enters the low-temperature adsorption system T2 via the ninth pipe F9.

[0041] In this embodiment, the low-temperature adsorption system T2 is a temperature-switching adsorption system. The adsorption tower is filled with molecular sieves or activated carbon to remove impurities that are easily frozen during further cooling. The hydrogen outlet of the low-temperature adsorption system T2 is connected to the inlet of the first hydrogen pipeline H1. The hydrogen purified in the low-temperature adsorption system T2 enters the cryogenic unit through the first hydrogen pipeline H1.

[0042] The second hot-side inlet of the first-stage heat exchanger HE1 is connected to the outlet of the hydrogen compressor unit K1 via the second hydrogen pipeline H2. The second hot-side outlet of the first-stage heat exchanger HE1 is connected to the second hot-side inlet of the second-stage heat exchanger HE3 via the third hydrogen pipeline H3. The second hot-side outlet of the second-stage heat exchanger HE3 has two branches: one branch is connected to the hot-side inlet of the third-stage heat exchanger HE4 via the fourth hydrogen pipeline H4, and the other branch is connected to the inlet of the first-stage hydrogen expander unit E1 via the fifth hydrogen pipeline H5.

[0043] The hot-side outlet of the third-stage heat exchanger HE4 is connected to the inlet of hydrogen pipeline H6 (sixth stage). The outlet of hydrogen pipeline H6 and the outlet of hydrogen pipeline H1 merge at the inlet of hydrogen pipeline H11 (eleventh stage). The outlet of hydrogen pipeline H11 (eleventh stage) has two branches: one branch connects to the inlet of the second-stage hydrogen expander E2 via hydrogen pipeline H9 (ninth stage), and the other branch connects to the hot-side inlet of the fourth-stage heat exchanger HE6. The outlet of the second-stage hydrogen expander E2 is connected to the inlet of hydrogen pipeline H10 (tenth stage).

[0044] The hot-side outlet of the fourth-stage heat exchanger HE6 is connected to the hot-side inlet of the fifth-stage heat exchanger HE7 via hydrogen pipelines H12 and H13. A first-stage hydrogen throttling valve V2 is installed between hydrogen pipelines H12 and H13.

[0045] The hot-side outlet of the five-stage heat exchanger HE7 is connected to the inlet of the hydrogen separator D1 via hydrogen pipelines H14 and H15. A two-stage hydrogen throttling valve V3 is installed between hydrogen pipelines H14 and H15.

[0046] Hydrogen separator D1 has a gas outlet at the top and a first liquid outlet and a second liquid outlet at the bottom, forming two branches. The gas outlet at the top of hydrogen separator D1 is connected to the inlet of hydrogen pipeline H17 (number 17). The first liquid outlet at the bottom of hydrogen separator D1 is connected to the inlet of hydrogen pipeline H16 (number 16). The outlet of hydrogen pipeline H17 merges with that of hydrogen pipeline H16 and connects to the cold side inlet of the fifth-stage heat exchanger HE7. The second liquid outlet at the bottom of hydrogen separator D1 is directly connected to the liquid hydrogen storage tank.

[0047] The cold-side outlet of the fifth-stage heat exchanger HE7 is connected to the inlet of hydrogen pipeline H18 (the eighteenth hydrogen pipeline). The outlet of hydrogen pipeline H10 merges with hydrogen pipeline H18 and then connects to the cold-side inlet of the fourth-stage heat exchanger HE6. The cold-side outlet of the fourth-stage heat exchanger HE6 is connected to the inlet of hydrogen pipeline H19. The outlet of hydrogen pipeline H8 merges with hydrogen pipeline H19 and then connects to the cold-side inlet of the condenser HE5.

[0048] The cold-side outlet of condenser HE5 is connected to the cold-side inlet of tertiary heat exchanger HE4 via hydrogen pipeline H20 (number 20). The cold-side outlet of tertiary heat exchanger HE4 is connected to the first cold-side inlet of secondary heat exchanger HE3 via hydrogen pipeline H21 (number 21). The first cold-side outlet of secondary heat exchanger HE3 is connected to the first cold-side inlet of primary heat exchanger HE1 via pipeline H22 (number 22). The first cold-side outlet of primary heat exchanger HE1 is connected to the inlet of hydrogen compressor unit K1 via pipeline H23 (number 23). The outlet of hydrogen compressor unit K1 is connected to the second hot-side inlet of primary heat exchanger HE1 via hydrogen pipeline H2 (number 2), forming a hydrogen Claude cycle.

[0049] In this embodiment, the primary heat exchanger HE1, reboiler HE2, secondary heat exchanger HE3, tertiary heat exchanger HE4, condenser HE5, quaternary heat exchanger HE6, and quinary heat exchanger HE7 are all aluminum plate-fin heat exchangers. Among them, the product channels of quaternary heat exchanger HE6 and quinary heat exchanger HE7 are filled with corresponding catalytic performance of ortho-parahydrogen conversion catalyst according to the refrigeration temperature zone.

[0050] In this embodiment, an atmospheric pressure cold box and a vacuum cold box are provided. The primary heat exchanger HE1, reboiler HE2, secondary heat exchanger HE3, and carbon monoxide throttling valve V1 are installed in the atmospheric pressure cold box. The distillation column T1, cryogenic adsorption system T2, tertiary heat exchanger HE4, primary hydrogen expander E1, condenser HE5, secondary hydrogen expander E2, quaternary heat exchanger HE6, quinary heat exchanger HE7, primary hydrogen throttling valve V2, secondary hydrogen throttling valve V3, and hydrogen separator D1 are installed in the vacuum cold box.

[0051] This embodiment also provides the steps for using the integrated system, as follows:

[0052] (1) The 3.0 MPa, 40℃ HyCO synthesis gas from upstream purification first enters the first-stage heat exchanger HE1 in the atmospheric pressure cold box through the first pipe F1, where it is cooled to -90~-100℃. Then it enters the reboiler HE2, where it is cooled to -145℃, and then enters the second-stage heat exchanger HE3, where it is further cooled to -190~-195℃. Finally, it enters the distillation column T1 for component separation. A portion of the liquid at the bottom of the distillation column T1 enters the reboiler HE2 through the fifth pipe F5, where it is heated and vaporized, and then returns to the bottom of the distillation column T1 through the sixth pipe F6. The other portion of the liquid at the bottom of the distillation column T1 is throttled and reheated, and exits the atmospheric pressure cold box as carbon monoxide product gas. Provided that the vapor phase temperature at the top of the distillation column is not lower than the melting point of carbon monoxide, and the hydrogen purity is not lower than 99.9%, the vapor phase at the top of the distillation column enters the condenser HE5 through the seventh pipe F7. In condenser HE5, the condensed liquid phase returns to the top of distillation column T1 through the eighth pipe F8, while the uncondensed gas phase enters the low-temperature adsorption system T2 through the ninth pipe F9.

[0053] (2) After purification by the low-temperature adsorption system T2, hydrogen with a purity of not less than 99.99% is directly merged with hydrogen pipeline H6 through the first hydrogen pipeline H1 and enters the cryogenic unit for hydrogen Claude cycle. Hydrogen from the outlet of hydrogen compressor unit K1 enters the first-stage heat exchanger HE1 through the second hydrogen pipeline H2 and is cooled to -145℃, then enters the second-stage heat exchanger HE3 and is cooled to -190~-195℃. Subsequently, it splits into two branches. One branch enters the third-stage heat exchanger HE4 and is cooled to -220℃, while the other branch enters the first-stage hydrogen expander unit E1 for expansion and cooling to 0.12 MPa and -237℃, and then merges with hydrogen pipeline H8 through the eighth hydrogen pipeline and enters the return hydrogen pipeline H19. The hot-side outlet of the third-stage heat exchanger HE4 merges with the first-stage hydrogen pipeline H1 via the sixth hydrogen pipeline H6, leading to the eleventh-stage hydrogen pipeline H11. The outlet of the eleventh-stage hydrogen pipeline H11 has two branches. One branch enters the second-stage hydrogen expander E2 for expansion and cooling to 0.125 MPa and -250°C, then merges with the return hydrogen pipeline H18. The second branch is cooled to -250.6°C in the fourth-stage heat exchanger HE6, where the secondary hydrogen content is increased to over 90% under the action of the positive-to-negative conversion catalyst. The hot-side outlet of the fourth-stage heat exchanger HE6 is throttled and cooled to 0.20 MPa and -251.5°C via the first-stage hydrogen throttling valve V2, then enters the fifth-stage heat exchanger HE7 for cooling to complete liquefaction, where the secondary hydrogen content is increased to over 98% under the action of the positive-to-negative conversion catalyst. The hot-side outlet of the fifth-stage heat exchanger HE7 is throttled and cooled to 0.13 MPa and -253.4℃ via the second-stage hydrogen throttling valve V3, and then enters the hydrogen separator D1. The gas phase at the top of the hydrogen separator D1 merges with the hydrogen 16th pipe through the seventeenth hydrogen pipe H17. A portion of the liquid hydrogen at the bottom outlet of the hydrogen separator D1 merges with the sixteenth hydrogen pipe H16, and the remaining liquid hydrogen enters the liquid hydrogen storage tank as a product.

[0054] (3) Another part of the liquid hydrogen at the bottom of the hydrogen separator D1 enters the cold side inlet of the fifth-stage heat exchanger HE7 through the sixteenth hydrogen pipe H16. The cold side outlet of the fifth-stage heat exchanger HE7 merges with the tenth hydrogen pipe H10 to the eighteenth hydrogen pipe H18. The eighteenth hydrogen pipe H18 is connected to the cold side inlet of the fourth-stage heat exchanger HE6. The cold side outlet of the fourth-stage heat exchanger HE6 merges with the nineteenth hydrogen pipe H19. The nineteenth hydrogen pipe H19 is connected to the cold side inlet of the condenser HE5. The cold side outlet of the condenser HE5 is connected to the cold side inlet of the third-stage heat exchanger HE4 through the twentieth hydrogen pipe H20. The cold side outlet of the third-stage heat exchanger HE4 exits the cold box after passing through the twenty-first hydrogen pipe H21, the second-stage heat exchanger HE3, the twenty-second pipe H22, the first-stage heat exchanger HE1, and the twenty-third pipe H23. The twenty-third pipe H23 is pressurized by the hydrogen compressor unit K1 and then connected to the second hydrogen pipe H2, forming a hydrogen Claude cycle.

[0055] The integrated system provided by this invention cools the HyCO synthesis gas from upstream purification in a pre-cooling box, and then it enters a distillation column for component separation. The CO produced at the bottom of the column is throttled and reheated before exiting the cold box, while the high-purity, low-temperature hydrogen produced at the top of the column is directly used as the feed gas for hydrogen liquefaction. The hydrogen purified by the low-temperature adsorption system is further cooled using a single-pressure hydrogen Claude cycle refrigeration process. After being throttled and cooled to the liquefaction temperature, the gaseous hydrogen and part of the liquid hydrogen are combined into the refrigeration cycle, and the remaining liquid hydrogen enters the storage tank as a product.

[0056] The technical solution proposed in this invention is a co-production system that highly couples the cryogenic separation process of HyCO syngas and the hydrogen liquefaction process. This reduces the thermodynamic irreversibility of the two independent systems, achieving highly efficient integration of cryogenic separation of HyCO syngas and hydrogen liquefaction. This simplifies the process, reduces energy consumption, and saves on project land and equipment investment. Based on liquid hydrogen, the specific energy consumption of the entire integrated system is less than 6.8 kWh / kg liquid hydrogen, solving the problem of high energy consumption in cryogenic separation of HyCO and hydrogen liquefaction, and significantly reducing the cost of co-production of CO and liquid hydrogen.

[0057] 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. An integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas, characterized in that, The integrated system includes a precooling unit, a HyCO separation unit, a cryogenic adsorption unit, a cryogenic unit, and a liquefaction unit; the precooling unit includes a primary heat exchanger (HE1), a secondary heat exchanger (HE3), and a hydrogen compressor unit (K1); the HyCO separation unit includes a reboiler (HE2), a distillation column (T1), and a condenser (HE5); the cryogenic adsorption unit includes a cryogenic adsorption system (T2); the cryogenic unit includes a tertiary heat exchanger (HE4), a quaternary heat exchanger (HE6), a primary hydrogen expander unit (E1), and a secondary hydrogen expander unit (E2); the liquefaction unit includes a quinary heat exchanger (HE7), a hydrogen separator (D1), and a liquid hydrogen storage tank; HyCO synthesis gas from upstream purification enters the precooling unit. After precooling in the precooling unit, it enters the distillation column (T1) in the HyCO separation unit for separation, yielding carbon monoxide product gas and hydrogen. The hydrogen is purified by the low-temperature adsorption unit and then enters the cryogenic unit. Part of the low-temperature hydrogen separated in the cryogenic unit provides cooling for the precooling unit, and the other part enters the liquefaction unit to prepare liquid hydrogen. The specific structure is as follows: HyCO synthesis gas from upstream purification is connected to the first hot-side inlet of the first-stage heat exchanger (HE1) via a first pipe (F1); the first hot-side outlet of the first-stage heat exchanger (HE1) is connected to the hot-side inlet of the reboiler (HE2) via a second pipe (F2); the hot-side outlet of the reboiler (HE2) is connected to the first hot-side inlet of the second-stage heat exchanger (HE3) via a third pipe (F3); a pre-cooling cycle is also provided between the first-stage heat exchanger (HE1) and the second-stage heat exchanger (HE3); The first hot-side outlet of the secondary heat exchanger (HE3) is connected to the middle inlet of the distillation column (T1) via the fourth pipe (F4); the bottom of the distillation column (T1) is provided with a first liquid outlet and a second liquid outlet; the first liquid outlet at the bottom of the distillation column (T1) returns to the bottom of the distillation column (T1) after passing through the fifth pipe (F5), the cold-side inlet of the reboiler (HE2), the cold-side outlet of the reboiler (HE2), and the sixth pipe (F6); the second liquid outlet at the bottom of the distillation column (T1) is connected to the carbon monoxide inlet of the secondary heat exchanger (HE3) via the first carbon monoxide pipe (C1) and the second carbon monoxide pipe (C2); the carbon monoxide outlet of the secondary heat exchanger (HE3) is connected to the carbon monoxide inlet of the primary heat exchanger (HE1) via the third carbon monoxide pipe (C3); the carbon monoxide outlet of the primary heat exchanger (HE1) discharges the carbon monoxide product gas through the fourth carbon monoxide pipe (C4); The distillation column (T1) has a gas outlet at the top, which is connected to the gas inlet of the condenser (HE5) via the seventh pipe (F7); the liquid outlet of the condenser (HE5) is connected to the top of the distillation column (T1) via the eighth pipe (F8); the gas outlet of the condenser (HE5) is connected to the inlet of the low-temperature adsorption system (T2) via the ninth pipe (F9); the hydrogen outlet of the low-temperature adsorption system (T2) is connected to the inlet of the first hydrogen pipe (H1). The second hot-side inlet of the first-stage heat exchanger (HE1) is connected to the outlet of the hydrogen compressor unit (K1) via the second hydrogen pipeline (H2); the second hot-side outlet of the first-stage heat exchanger (HE1) is connected to the second hot-side inlet of the second-stage heat exchanger (HE3) via the third hydrogen pipeline (H3); the second hot-side outlet of the second-stage heat exchanger (HE3) is provided with two branches, one branch is connected to the hot-side inlet of the third-stage heat exchanger (HE4) via the fourth hydrogen pipeline (H4), and the other branch is connected to the inlet of the first-stage hydrogen expander unit (E1) via the fifth hydrogen pipeline (H5); the outlet of the first-stage hydrogen expander unit (E1) is connected to the inlet of the eighth hydrogen pipeline (H8). The hot-side outlet of the third-stage heat exchanger (HE4) is connected to the inlet of the sixth hydrogen pipeline (H6); the outlet of the sixth hydrogen pipeline (H6) and the outlet of the first hydrogen pipeline (H1) merge to the inlet of the eleventh hydrogen pipeline (H11); the outlet of the eleventh hydrogen pipeline (H11) is provided with two branches, one branch is connected to the inlet of the second-stage hydrogen expander unit (E2) through the ninth hydrogen pipeline (H9), and the other branch is connected to the hot-side inlet of the fourth-stage heat exchanger (HE6); the outlet of the second-stage hydrogen expander unit (E2) is connected to the inlet of the tenth hydrogen pipeline (H10). The hot-side outlet of the fourth-stage heat exchanger (HE6) is connected to the hot-side inlet of the fifth-stage heat exchanger (HE7) via hydrogen pipelines twelfth (H12) and thirteenth (H13) in sequence. The hot-side outlet of the fifth-stage heat exchanger (HE7) is connected to the inlet of the hydrogen separator (D1) via hydrogen pipelines fourteenth (H14) and fifteenth (H15) in sequence. The hydrogen separator (D1) has a gas outlet at the top and a first liquid outlet and a second liquid outlet at the bottom. The gas outlet at the top of the hydrogen separator (D1) is connected to the inlet of hydrogen pipeline seventeenth (H17), and the first liquid outlet at the bottom of the hydrogen separator (D1) is connected to the inlet of hydrogen pipeline sixteenth (H16). The outlet of hydrogen pipeline seventeenth (H17) merges with that of hydrogen pipeline sixteenth (H16) and is then connected to the cold-side inlet of the fifth-stage heat exchanger (HE7). The second liquid outlet at the bottom of the hydrogen separator (D1) is connected to a liquid hydrogen storage tank. The cold-side outlet of the fifth-stage heat exchanger (HE7) is connected to the inlet of the eighteenth hydrogen pipeline (H18); the outlet of the tenth hydrogen pipeline (H10) merges with the eighteenth hydrogen pipeline (H18) and then connects to the cold-side inlet of the fourth-stage heat exchanger (HE6); the cold-side outlet of the fourth-stage heat exchanger (HE6) is connected to the inlet of the nineteenth hydrogen pipeline (H19); the outlet of the eighth hydrogen pipeline (H8) merges with the nineteenth hydrogen pipeline (H19) and then connects to the cold-side inlet of the condenser (HE5); the cold-side outlet of the condenser (HE5) connects to the cold-side inlet of the third-stage heat exchanger (HE4) via the twentieth hydrogen pipeline (H20). The connection is as follows: the cold-side outlet of the third-stage heat exchanger (HE4) is connected to the first cold-side inlet of the second-stage heat exchanger (HE3) via the twenty-first hydrogen pipe (H21); the first cold-side outlet of the second-stage heat exchanger (HE3) is connected to the first cold-side inlet of the first-stage heat exchanger (HE1) via the twenty-second pipe (H22); the first cold-side outlet of the first-stage heat exchanger (HE1) is connected to the inlet of the hydrogen compressor unit (K1) via the twenty-third pipe (H23), and the outlet of the hydrogen compressor unit (K1) is connected to the second hot-side inlet of the first-stage heat exchanger (HE1) via the second hydrogen pipe (H2), thus forming a hydrogen Claude cycle.

2. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, A carbon monoxide throttling valve (V1) is provided between the first carbon monoxide pipe (C1) and the second carbon monoxide pipe (C2).

3. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, A primary hydrogen throttle valve (V2) is installed between the twelfth hydrogen pipeline (H12) and the thirteenth hydrogen pipeline (H13).

4. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, A two-stage hydrogen throttling valve (V3) is provided between the fourteenth hydrogen pipeline (H14) and the fifteenth hydrogen pipeline (H15).

5. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, The precooling cycle employs liquid nitrogen refrigeration, nitrogen cycle refrigeration, or mixed refrigerant refrigeration technology.

6. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, The primary heat exchanger (HE1), reboiler (HE2), secondary heat exchanger (HE3), tertiary heat exchanger (HE4), condenser (HE5), quaternary heat exchanger (HE6), and quinary heat exchanger (HE7) are all aluminum plate-fin heat exchangers. The product channels of the quaternary heat exchanger (HE6) and quinary heat exchanger (HE7) are filled with corresponding catalytic performance of ortho- and para-hydrogen conversion catalysts according to the refrigeration temperature zone.

7. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, The low-temperature adsorption system (T2) is a temperature-switching adsorption system, and the adsorption tower is filled with molecular sieves or activated carbon to remove impurities that are easily frozen during the cooling process.

8. The integrated system for cryogenic separation and hydrogen liquefaction of HyCO synthesis gas according to claim 1, characterized in that, The primary heat exchanger (HE1), reboiler (HE2), and secondary heat exchanger (HE3) are housed in an ambient temperature cold box; the distillation column (T1), low-temperature adsorption system (T2), tertiary heat exchanger (HE4), primary hydrogen expander (E1), condenser (HE5), secondary hydrogen expander (E2), quaternary heat exchanger (HE6), quinary heat exchanger (HE7), and hydrogen separator (D1) are housed in a vacuum cold box.

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