Device and method for extracting helium from natural gas flash steam and co-producing liquid hydrogen
By combining the LNG liquefied cold box and hydrogen, helium and neon mixed gas expansion and refrigeration cycle method, the problem of helium purity and energy consumption in helium is solved in natural gas flash vapor, and efficient helium and liquid hydrogen production is achieved, reducing energy consumption and alloy dehydrogenation unit load.
Patent Information
- Application Number
- CN202510241969.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-07-18
AI Technical Summary
In the existing natural gas flash vapor helium extraction technology, trace hydrogen in helium is difficult to remove, the system energy consumption is high, the product purity does not meet the standards, and there is a lack of effective combination of the natural gas flash vapor helium extraction and hydrogen liquefaction cogeneration process.
The LNG liquefaction cold box, hydrogen liquefaction cold box, nitrogen removal tower cold box, helium recovery cold box, membrane separation hydrogen extraction helium unit, PSA refined hydrogen helium unit and alloy dehydrogenation unit are adopted, combined with the hydrogen, helium mixed gas expansion and refrigeration cycle, hydrogen and helium separation and liquid hydrogen are achieved.
The production of high-purity helium and liquid hydrogen has been achieved, with the purity of helium not less than 99.9995%, the purity of liquid hydrogen not less than 99.99%, and the specific energy consumption of hydrogen helium and neon expansion refrigeration cycle is less than 6.0kWh/kg liquid hydrogen, which reduces the load of alloy dehydrogenation units and avoids the use of large compressors and expanders.
Smart Images
Figure CN120333062A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of refrigeration and cryogenic engineering, and particularly relates to a natural gas flash vapor helium extraction and liquid hydrogen co-production device and method. Background Art
[0002] Helium is a substance with the lowest known melting and boiling points, and has unique properties such as low density, low solubility, chemical inertness, and high thermal conductivity. These properties make helium widely used in various fields. In the field of advanced manufacturing, helium is used in liquid fuel rockets, manned deep diving, fourth-generation nuclear reactors, semiconductor manufacturing, quantum computers, precision analytical instruments, and nuclear magnetic resonance. Due to such extensive uses, helium is considered a strategic rare gas related to national security and the development of high-tech industries, and is called the "gold gas". Since helium resources in China are scarce, the extraction cost is relatively high and the economic benefits are limited, resulting in an import dependence of more than 95% for industrial helium in China. Therefore, the strategic significance of helium resources is very prominent, and the technology and equipment for producing helium have become the key link restricting the development of China's high-tech industries.
[0003] Helium is usually extracted from natural gas. Currently, the commonly used natural gas helium extraction technologies include absorption method, diffusion method, hydrate method, adsorption method, cryogenic method, membrane separation method, and combined method, etc. Among them, the adsorption method, cryogenic method, membrane separation method, and combined method are the most widely used. Due to the complex process of the helium extraction device and high requirements for product purity, there are still problems such as high energy consumption, unstable operation, and unqualified product purity in the current domestic helium extraction devices.
[0004] The natural gas flash vapor helium extraction process usually produces a high-purity hydrogen-helium mixed gas. On the one hand, it is difficult to remove trace hydrogen in helium; on the other hand, recovering hydrogen in the high-purity hydrogen-helium mixed gas has high added value. LNG plants can usually provide cooling capacity as low as about -170°C. Using the LNG cold box to provide precooling capacity for the separation of the hydrogen-helium mixed gas, and further adopting a hydrogen-helium-neon mixed gas refrigeration cycle to realize hydrogen-helium separation and produce liquid hydrogen at the same time. Thus, it can be seen that there is an inherent demand for production and an energy-saving prospect in the co-production of natural gas flash vapor helium extraction and hydrogen liquefaction.
[0005] However, there is currently no relevant research on the co-production process of natural gas flash vapor helium extraction and hydrogen liquefaction. How to creatively integrate the two processes to achieve low-energy consumption operation and simultaneously meet the requirements of natural gas flash vapor helium extraction and liquid hydrogen products has become the core problem that urgently needs to be solved in the process design of natural gas flash vapor helium extraction and hydrogen liquefaction co-production. Summary of the Invention
[0006] The object of the present invention is to solve the problems in the prior art, such as the difficulty in removing trace hydrogen in helium during the process of helium production by flash vaporization of natural gas and co-producing liquid hydrogen, high system energy consumption, and unqualified product purity. The present invention provides a device for producing helium by flash vaporization of natural gas and co-producing liquid hydrogen, which can produce helium with a purity of not less than 99.9995% while by-producing liquid hydrogen, and the specific energy consumption of the hydrogen-helium-neon expansion refrigeration cycle is lower than 6.0 kWh / kg of liquid hydrogen.
[0007] To achieve the above object, the specific technical solutions adopted by the present invention are as follows:
[0008] In the first aspect, the present invention provides a device for producing helium by flash vaporization of natural gas and co-producing liquid hydrogen, which includes an LNG liquefaction cold box, an LNG storage tank, a hydrogen liquefaction cold box, a liquid hydrogen storage tank, a denitrification tower cold box, a helium recovery cold box, a membrane separation hydrogen-helium extraction unit, a PSA refined hydrogen-helium unit, and an alloy dehydrogenation unit;
[0009] Wherein, a primary heat exchanger is provided in the LNG liquefaction cold box; the hydrogen liquefaction cold box includes a secondary heat exchanger, a tertiary heat exchanger, a throttle valve, a liquid hydrogen separation tank, and an expansion unit; the denitrification tower cold box includes a denitrification tower, a denitrification tower reboiler, and a BOG heat exchanger; a helium recovery tank is provided in the helium recovery cold box; the membrane separation hydrogen-helium extraction unit includes a primary membrane, a secondary membrane, and an intermembrane compressor; an adsorption tower group is provided in the PSA refined hydrogen-helium unit; and an alloy column group is provided in the alloy hydrogen absorption unit;
[0010] The LNG liquefaction cold box liquefies the natural gas from upstream compression and purification by using a mixed refrigerant cycle, so as to obtain LNG products and send them to the LNG storage tank; the denitrification tower cold box receives the BOG volatilized from the LNG storage tank, recovers the LNG therein, and sends the top gas to the membrane separation hydrogen-helium extraction unit and the PSA refined hydrogen-helium unit in sequence, so as to obtain a high-purity hydrogen-helium mixture with a purity of not less than 99.999%; the hydrogen liquefaction cold box preliminarily separates the high-purity hydrogen-helium mixture by using the cooling capacity provided by the hydrogen-helium-neon mixture expansion refrigeration cycle, so as to obtain liquid hydrogen products and helium with a purity of not less than 99.9%; the alloy dehydrogenation unit adsorbs trace hydrogen in helium, so as to obtain helium products with a purity of not less than 99.9995%.
[0011] Preferably, the specific structure is as follows:
[0012] The natural gas from upstream compression and purification is connected to the first heat side inlet of the primary heat exchanger through a first pipeline; the first heat side outlet of the primary heat exchanger is connected to the inlet of the LNG storage tank through a second pipeline; the top outlet of the LNG storage tank is connected to the first cold side inlet of the primary heat exchanger through a third pipeline;
[0013] The first cold-side outlet of the primary heat exchanger is sequentially connected to the inlet of the denitrification tower reboiler through the fourth pipeline and the fifth pipeline; the outlet of the denitrification tower reboiler is connected to the middle inlet of the denitrification tower through the sixth pipeline; the top outlet of the denitrification tower is connected to the inlet of the BOG heat exchanger through the seventh pipeline; the bottom outlet of the denitrification tower is connected to the inlet of the LNG storage tank through the eighth pipeline to recover LNG; the outlet of the BOG heat exchanger is connected to the inlet of the ninth pipeline, and the outlet of the ninth pipeline is divided into two branches, namely the tenth pipeline and the eleventh pipeline;
[0014] The inlet of the primary membrane is connected to the tenth pipeline through the twelfth pipeline; the outlet of the primary membrane is sequentially connected to the inlet of the intermembrane compressor through the thirteenth pipeline and the fourteenth pipeline; the top outlet of the primary membrane is connected to the inlet of the helium recovery tank through the fifteenth pipeline; the top outlet of the helium recovery tank is converged with the outlet of the eleventh pipeline through the sixteenth pipeline to the inlet of the seventeenth pipeline; the outlet of the seventeenth pipeline is connected to the inlet of the BOG compressor; the outlet of the BOG compressor is converged with the outlet of the fourth pipeline through the eighteenth pipeline to the inlet of the fifth pipeline; the outlet of the intermembrane compressor is connected to the inlet of the secondary membrane through the nineteenth pipeline; the outlet of the secondary membrane is connected to the inlet of the crude helium compressor through the twentieth pipeline; the top outlet of the secondary membrane is converged with the outlet of the tenth pipeline through the twenty-first pipeline to the inlet of the twelfth pipeline;
[0015] The outlet of the crude helium compressor is connected to the inlet of the twenty-second pipeline, and the outlet of the twenty-second pipeline is divided into four branches, namely the twenty-third pipeline, the twenty-fourth pipeline, the twenty-fifth pipeline and the twenty-sixth pipeline; the outlets of the twenty-third pipeline, the twenty-fourth pipeline, the twenty-fifth pipeline and the twenty-sixth pipeline are respectively connected to the inlets of the first adsorption tower, the second adsorption tower, the third adsorption tower and the fourth adsorption tower; the outlets of the first adsorption tower, the second adsorption tower, the third adsorption tower and the fourth adsorption tower are respectively converged through the twenty-seventh pipeline, the twenty-eighth pipeline, the twenty-ninth pipeline and the thirtieth pipeline and then divided into two branches, namely the thirty-first pipeline and the thirty-second pipeline;
[0016] The outlet of the thirty-second pipeline is converged with the outlet of the thirteenth pipeline to the inlet of the fourteenth pipeline; the outlet of the thirty-first pipeline is connected to the second hot-side inlet of the primary heat exchanger, and the second hot-side outlet of the primary heat exchanger is connected to the first hot-side inlet of the secondary heat exchanger through the thirty-third pipeline; the first hot-side outlet of the secondary heat exchanger is sequentially connected to the inlet of the liquid hydrogen separation tank through the thirty-fourth pipeline, the throttle valve and the thirty-fifth pipeline;
[0017] The top outlet of the liquid hydrogen separation tank is successively connected to the inlet of the 39th pipeline after passing through the 36th pipeline, the first cold-side inlet of the secondary heat exchanger, the first cold-side outlet of the secondary heat exchanger, the 38th pipeline, the first cold-side inlet of the tertiary heat exchanger, and the first cold-side outlet of the tertiary heat exchanger. The outlet of the 39th pipeline is divided into three branches: the 40th pipeline, the 41st pipeline, and the 42nd pipeline. The 40th pipeline, the 41st pipeline, and the 42nd pipeline are respectively connected to the inlets of the first alloy column, the second alloy column, and the third alloy column. The outlets of the first alloy column, the second alloy column, and the third alloy column are respectively converged to the inlet of the 46th pipeline through the 43rd pipeline, the 44th pipeline, and the 45th pipeline. The outlet of the 46th pipeline is the helium product.
[0018] The bottom outlet of the liquid hydrogen separation tank is connected to the inlet of the liquid hydrogen storage tank through the 37th pipeline to obtain liquid hydrogen products.
[0019] Furthermore, the specific structure of the hydrogen-helium-neon mixed gas expansion refrigeration cycle is as follows:
[0020] The inlet of the primary mixed gas compressor unit receives the hydrogen-helium-neon mixed gas from the 18th mixed gas pipeline. The outlet of the primary mixed gas compressor unit is connected to the inlet of the first mixed gas pipeline. The outlet of the first mixed gas pipeline is divided into two branches: the second mixed gas pipeline and the third mixed gas pipeline.
[0021] The outlet of the third mixed gas pipeline successively passes through the first hot-side inlet of the tertiary heat exchanger, the first hot-side outlet of the tertiary heat exchanger, the 6th mixed gas pipeline, the primary expansion unit, and the 11th mixed gas pipeline and is connected to the fourth cold-side inlet of the secondary heat exchanger. The fourth cold-side outlet of the secondary heat exchanger successively passes through the 14th mixed gas pipeline, the fourth cold-side inlet of the tertiary heat exchanger, the fourth cold-side outlet of the tertiary heat exchanger, and the 17th mixed gas pipeline and then converges to the inlet of the 18th mixed gas pipeline.
[0022] The second mixed gas pipeline is connected to the inlet of the secondary mixed gas compressor unit; the outlet of the secondary mixed gas compressor unit is divided into two branches, namely the fourth mixed gas pipeline and the fifth mixed gas pipeline; the outlet of the fourth mixed gas pipeline sequentially passes through the second hot side inlet of the tertiary heat exchanger, the second hot side outlet of the tertiary heat exchanger, the seventh mixed gas pipeline, the secondary expansion unit, and the tenth mixed gas pipeline and is connected to the third cold side inlet of the secondary heat exchanger; the third cold side outlet of the secondary heat exchanger sequentially passes through the thirteenth mixed gas pipeline, the third cold side inlet of the tertiary heat exchanger, the third cold side outlet of the tertiary heat exchanger, and the sixteenth mixed gas pipeline and then converges to the inlet of the eighteenth mixed gas pipeline; the outlet of the fifth mixed gas pipeline sequentially passes through the third hot side inlet of the tertiary heat exchanger, the third hot side outlet of the tertiary heat exchanger, the eighth mixed gas pipeline, the tertiary expansion unit, and the ninth mixed gas pipeline and is connected to the second cold side inlet of the secondary heat exchanger; the second cold side outlet of the secondary heat exchanger sequentially passes through the twelfth mixed gas pipeline, the second cold side inlet of the tertiary heat exchanger, the second cold side outlet of the tertiary heat exchanger, and the fifteenth mixed gas pipeline and then converges to the inlet of the eighteenth mixed gas pipeline.
[0023] The outlet of the eighteenth mixed gas pipeline is connected to the inlet of the primary mixed gas compressor unit, forming a hydrogen-helium-neon mixed gas expansion refrigeration cycle.
[0024] Furthermore, a refrigerant storage tank including a hydrogen-helium-neon recovery tank, a hydrogen storage tank, a helium storage tank, and a neon storage tank is also provided; the hydrogen-helium-neon recovery tank, the hydrogen storage tank, the helium storage tank, and the neon storage tank are all connected to the eighteenth mixed gas pipeline through pipelines for adjusting the composition of the hydrogen-helium-neon mixed gas.
[0025] Furthermore, the LNG liquefaction cold box is an atmospheric pressure cold box, and the hydrogen liquefaction cold box is a vacuum cold box.
[0026] Furthermore, the primary heat exchanger, the secondary heat exchanger, and the tertiary heat exchanger are all aluminum plate-fin heat exchangers, and a para-hydrogen to ortho-hydrogen conversion catalyst with corresponding temperature zone catalytic performance is filled in the product gas channel of the secondary heat exchanger along the fluid flow direction of the channel.
[0027] In a second aspect, the present invention provides a method for preparing helium gas and liquid hydrogen by using the natural gas flash vapor stripping helium and co-producing liquid hydrogen device described in the first aspect, which is specifically as follows:
[0028] The natural gas from upstream compression and purification enters the first-stage heat exchanger in the LNG liquefaction cold box for heat exchange, and after being cooled to the liquefaction temperature, it exits the LNG liquefaction cold box and enters the LNG storage tank; the BOG gas at the top of the LNG storage tank then enters the first-stage heat exchanger in the LNG liquefaction cold box for heat exchange, and the heat-exchanged BOG gas then passes through the de-nitrogen tower cold box, the membrane separation hydrogen and helium extraction unit, the helium recovery unit, and the PSA refined hydrogen and helium unit to obtain a high-purity hydrogen and helium mixture of 99.999%; after the high-purity hydrogen and helium mixture enters the first-stage heat exchanger for heat exchange and is cooled to -160 to -170 °C, it then enters the second-stage heat exchanger in the hydrogen liquefaction cold box for heat exchange. At the same time, under the action of the catalyst filled in the second-stage heat exchanger, the para-hydrogen content is increased from 25% to over 97%. Then, it passes through a throttle valve for throttling and depressurization to 0.1 to 0.2 MPa while being cooled to -263 to -268 °C, and finally enters the liquid hydrogen separation tank for gas-liquid separation; the liquid hydrogen flows out from the bottom outlet of the liquid hydrogen separation tank and enters the liquid hydrogen storage tank, while the gas phase part flows out from the top outlet of the liquid hydrogen separation tank, is reheated successively through the second-stage heat exchanger and the third-stage heat exchanger, and then enters the alloy dehydrogenation unit for dehydrogenation to obtain 99.9995% helium;
[0029] In the hydrogen liquefaction cold box, hydrogen-helium-neon mixture expansion refrigeration is adopted: the inlet of the first-stage mixture compressor receives the hydrogen-helium-neon mixture from the third-stage heat exchanger in the hydrogen liquefaction cold box; a part of the gas at the outlet of the first-stage mixture compressor successively passes through the first-stage expansion unit, the second-stage heat exchanger, and the third-stage heat exchanger and returns to the first-stage mixture compressor; the remaining gas at the outlet of the first-stage mixture compressor is compressed by the second-stage mixture compressor, and a part of it successively passes through the second-stage expansion unit, the second-stage heat exchanger, and the third-stage heat exchanger and returns to the first-stage mixture compressor, and the other part successively passes through the third-stage expansion unit, the second-stage heat exchanger, and the third-stage heat exchanger and returns to the first-stage mixture compressor, forming a hydrogen-helium-neon mixture expansion refrigeration cycle; the first-stage mixture compressor also receives the hydrogen-helium-neon mixture after mixing from the hydrogen-helium-neon recovery tank, the hydrogen storage tank, the helium storage tank, and the neon storage tank.
[0030] Preferably, a mixed refrigerant cycle technology is adopted in the LNG liquefaction cold box.
[0031] Preferably, the hydrogen-helium-neon mixture consists of 20 - 30 mol% hydrogen, 55 - 65 mol% helium, and 10 - 20 mol% neon; in the hydrogen-helium-neon mixture expansion refrigeration cycle, the pressure is divided into three levels: 2 - 2.5 MPa, 0.8 - 0.9 MPa, and 0.3 - 0.4 MPa.
[0032] Preferably, the crude helium compressor pressurizes the hydrogen-helium mixture to 2.0 - 2.5 MPa.
[0033] Compared with the prior art, the present invention has the following beneficial effects:
[0034] (1) The helium production by flash vaporization of natural gas and liquid hydrogen co-production device provided by the present invention uses the LNG cold box to provide precooling capacity for the separation of hydrogen-helium mixture, and further adopts a hydrogen-helium-neon mixture refrigeration cycle to realize the separation of hydrogen and helium while producing liquid hydrogen. The specific energy consumption of the hydrogen-helium-neon expansion refrigeration cycle is lower than 6.0 kWh / kg liquid hydrogen, which is much lower than the specific energy consumption of 11.9 - 13.8 kWh / kg liquid hydrogen at the present stage.
[0035] (2) In the helium production by flash vaporization of natural gas and liquid hydrogen co-production device provided by the present invention, the cryogenic separation of hydrogen and helium greatly reduces the load of the alloy dehydrogenation unit and reduces the size of the alloy column.
[0036] (3) The helium production by flash vaporization of natural gas and liquid hydrogen co-production device provided by the present invention avoids the use of large-scale hydrogen / helium compressors and hydrogen / helium expanders. The sound speed of the hydrogen-helium-neon mixture with an average molecular weight of 6 - 8 g / mol is much lower than that of pure hydrogen / helium, reducing the manufacturing difficulty of compressors and expanders.
[0037] (4) The helium production by flash vaporization of natural gas and liquid hydrogen co-production device provided by the present invention has the advantages of high helium extraction rate and liquefaction rate, and high purity of helium and liquid hydrogen. It can achieve a helium product purity of not less than 99.9995% and a liquid hydrogen product purity of not less than 99.99%. Description of the Drawings
[0038] Figure 1 Schematic diagram of a helium production by flash vaporization of natural gas and liquid hydrogen co-production device provided for the embodiment;
[0039] Figure 2 Schematic diagram of the hydrogen-helium-neon mixture expansion refrigeration cycle in the embodiment.
[0040] In the figure: primary heat exchanger HE1, secondary heat exchanger HE2, tertiary heat exchanger HE3, throttle valve V1, helium recovery tank D1, LNG storage tank D2, liquid hydrogen separation tank D3, first alloy column D4, second alloy column D5, third alloy column D6, hydrogen-helium-neon recovery tank D7, hydrogen storage tank D8, helium storage tank D9, neon storage tank D10, primary membrane M1, secondary membrane M2, denitrification tower T1, first adsorption tower T2, second adsorption tower T3, third adsorption tower T4, fourth adsorption tower T5, denitrification tower reboiler C1, BOG heat exchanger C2, inter-membrane compressor K1, BOG compressor K2, crude helium compressor K3, primary mixed gas compressor unit K4, secondary mixed gas compressor unit K5, primary expansion unit E1, secondary expansion unit E2, tertiary expansion unit E3, first pipeline H1, second pipeline H2, third pipeline H3, fourth pipeline H4, fifth pipeline H5, sixth pipeline H6, seventh pipeline H7, eighth pipeline H8, ninth pipeline H9, tenth pipeline H10, eleventh pipeline H11, twelfth pipeline H12, thirteenth pipeline H13, fourteenth pipeline H14, fifteenth pipeline H15, sixteenth pipeline H16, seventeenth pipeline H17, eighteenth pipeline H18, nineteenth pipeline H19, twentieth pipeline H20, twenty-first pipeline H21, twenty-second pipeline H22, twenty-third pipeline H23, twenty-fourth pipeline H24, twenty-fifth pipeline H25, twenty-sixth pipeline H26, twenty-seventh pipeline H27, twenty-eighth pipeline H28, twenty-ninth pipeline H29, thirtieth pipeline H30, thirty-first pipeline H31, thirty-second pipeline H32, thirty-third pipeline H33, thirty-fourth pipeline H34, thirty-fifth pipeline H35, thirty-sixth pipeline H36, thirty-seventh pipeline H37, thirty-eighth pipeline H38, thirty-ninth pipeline H39, fortieth pipeline H40, forty-first pipeline H41, forty-second pipeline H42, forty-third pipeline H43, forty-fourth pipeline H44, forty-fifth pipeline H45, forty-sixth pipeline H46, first mixed gas pipeline L1, second mixed gas pipeline L2, third mixed gas pipeline L3, fourth mixed gas pipeline L4, fifth mixed gas pipeline L5, sixth mixed gas pipeline L6, seventh mixed gas pipeline L7, eighth mixed gas pipeline L8, ninth mixed gas pipeline L9, tenth mixed gas pipeline L10, eleventh mixed gas pipeline L11, twelfth mixed gas pipeline L12, thirteenth mixed gas pipeline L13, fourteenth mixed gas pipeline L14, fifteenth mixed gas pipeline L15, sixteenth mixed gas pipeline L16, seventeenth mixed gas pipeline L17, eighteenth mixed gas pipeline L18. Detailed implementation manners
[0041] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following will provide a detailed description of the specific embodiments of the present invention with reference to the accompanying drawings. A lot of specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflict.
[0042] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for the purpose of distinguishing descriptions, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features.
[0043] In the description of the present invention, it should be understood that when an element is considered to be "connected" to another element, it can be directly connected to the other element or indirectly connected, i.e., there is an intermediate element. In contrast, when an element is referred to as being "directly" connected to another element, there is no intermediate element.
[0044] As Figure 1 shown, as a preferred embodiment of the specific implementation manner of the present invention, this embodiment provides a natural gas flash vapor helium co-production liquid hydrogen device. The helium co-production liquid hydrogen device includes an LNG liquefaction cold box, a hydrogen liquefaction cold box, a denitrification tower cold box, a helium recovery cold box, a membrane separation hydrogen and helium unit, a PSA refined hydrogen and helium unit, an alloy dehydrogenation unit, as well as a BOG compressor K2, a crude helium compressor K3, a first-stage mixed gas compression unit K4, a second-stage mixed gas compression unit K5, a refrigerant storage tank, an LNG storage tank D2, and a liquid hydrogen storage tank. Among them, the refrigerant storage tank includes a hydrogen, helium, and neon recovery tank D7, a hydrogen storage tank D8, a helium storage tank D9, and a neon storage tank D10.
[0045] In this embodiment, the LNG liquefaction cold box is an atmospheric pressure cold box, and the hydrogen liquefaction cold box is a vacuum cold box. The LNG liquefaction cold box is provided with a first-stage heat exchanger HE1, and the LNG liquefaction cold box adopts a mixed refrigerant refrigeration cycle. The hydrogen liquefaction cold box is provided with a second-stage heat exchanger HE2, a third-stage heat exchanger HE3, a throttle valve V1, a liquid hydrogen separation tank D3, a first-stage expansion unit E1, a second-stage expansion unit E2, and a third-stage expansion unit E3. The denitrification tower cold box includes a denitrification tower T1, a denitrification tower reboiler C1, and a BOG heat exchanger C2. The helium recovery cold box is provided with a helium recovery tank D1. The membrane separation hydrogen and helium unit includes a first-stage membrane M1, a second-stage membrane M2, and an inter-membrane compressor K1. The PSA refined hydrogen and helium unit is provided with an adsorption tower group. The alloy hydrogen absorption unit is provided with an alloy column group.
[0046] The specific structure of the natural gas flash vapor helium co-production and liquid hydrogen device provided in this embodiment is as follows:
[0047] The natural gas from upstream compression and purification enters the LNG liquefaction cold box through the first pipeline H1, connects to the first hot side inlet of the primary heat exchanger HE1, and exchanges heat with the natural gas. The first hot side outlet of the primary heat exchanger HE1 is connected to the inlet of the LNG storage tank D2 outside the LNG cold box through the second pipeline H2. The top outlet of the LNG storage tank D2 is connected to the first cold side inlet of the primary heat exchanger HE1 through the third pipeline H3 for heat exchange.
[0048] The first cold side outlet of the primary heat exchanger HE1 is successively connected to the inlet of the denitrification tower reboiler C1 through the fourth pipeline H4 and the fifth pipeline H5. The outlet of the denitrification tower reboiler C1 is connected to the middle inlet of the denitrification tower T1 through the sixth pipeline H6. The top outlet of the denitrification tower T1 is connected to the inlet of the BOG heat exchanger C2 through the seventh pipeline H7. The outlet of the BOG heat exchanger C2 is connected to the inlet of the ninth pipeline H9, and the outlet of the ninth pipeline H9 is divided into two branches, namely the tenth pipeline H10 and the eleventh pipeline H11.
[0049] The inlet of the primary membrane M1 is connected to the tenth pipeline H10 through the twelfth pipeline H12. The outlet of the primary membrane M1 is successively connected to the inlet of the inter-membrane compressor K1 through the thirteenth pipeline H13 and the fourteenth pipeline H14. The top outlet of the primary membrane M1 is connected to the inlet of the helium recovery tank D1 through the fifteenth pipeline H15. The top outlet of the helium recovery tank D1 converges with the outlet of the eleventh pipeline H11 to the inlet of the seventeenth pipeline H17 through the sixteenth pipeline H16. The outlet of the seventeenth pipeline H17 is connected to the inlet of the BOG compressor K2. The outlet of the BOG compressor K2 converges with the outlet of the fourth pipeline H4 through the eighteenth pipeline H18 to the inlet of the fifth pipeline H5 and enters the denitrification tower reboiler C1 to form a cycle.
[0050] The outlet of the inter-membrane compressor K1 is connected to the inlet of the secondary membrane M2 through the nineteenth pipeline H19. The outlet of the secondary membrane M2 is connected to the inlet of the crude helium compressor K3 through the twentieth pipeline H20. The top outlet of the secondary membrane M2 converges with the outlet of the tenth pipeline H10 to the inlet of the twelfth pipeline H12 through the twenty-first pipeline H21.
[0051] The outlet of the crude helium compressor K3 is connected to the inlet of the twenty-second pipeline H22, and the outlet of the twenty-second pipeline H22 is divided into four branch lines: the twenty-third pipeline H23, the twenty-fourth pipeline H24, the twenty-fifth pipeline H25, and the twenty-sixth pipeline H26. The outlet of the twenty-third pipeline H23 is connected to the inlet of the first adsorption tower T2, the outlet of the twenty-fourth pipeline H24 is connected to the inlet of the second adsorption tower T3, the outlet of the twenty-fifth pipeline H25 is connected to the inlet of the third adsorption tower T4, and the outlet of the twenty-sixth pipeline H26 is connected to the inlet of the fourth adsorption tower T5. The outlet of the first adsorption tower T2 is connected to the inlet of the twenty-seventh pipeline H27, the outlet of the second adsorption tower T3 is connected to the inlet of the twenty-eighth pipeline H28, the outlet of the third adsorption tower T4 is connected to the inlet of the twenty-ninth pipeline H29, and the outlet of the fourth adsorption tower T5 is connected to the inlet of the thirtieth pipeline H30. The outlets of the twenty-seventh pipeline H27, the twenty-eighth pipeline H28, the twenty-ninth pipeline H29, and the thirtieth pipeline H30 converge and are then divided into two branch lines: the thirty-first pipeline H31 and the thirty-second pipeline H32.
[0052] The outlet of the thirty-second pipeline H32 converges with the outlet of the thirteenth pipeline H13 to the inlet of the fourteenth pipeline H14. The outlet of the thirty-first pipeline H31 is connected to the second hot-side inlet of the primary heat exchanger HE1. The second hot-side outlet of the primary heat exchanger HE1 is connected to the first hot-side inlet of the secondary heat exchanger HE2 through the thirty-third pipeline H33. The first hot-side outlet of the secondary heat exchanger HE2 sequentially passes through the thirty-fourth pipeline H34 and the thirty-fifth pipeline H35 and is connected to the inlet of the liquid hydrogen separation tank D3. A throttle valve V1 is provided between the thirty-fourth pipeline H34 and the thirty-fifth pipeline H35.
[0053] The top outlet of the liquid hydrogen separation tank D3 is connected to the first cold-side inlet of the secondary heat exchanger HE2 through the thirty-sixth pipeline H36 for heat exchange. The first cold-side outlet of the secondary heat exchanger HE2 is connected to the first cold-side inlet of the tertiary heat exchanger through the thirty-eighth pipeline H38. The first cold-side outlet of the tertiary heat exchanger is connected to the thirty-ninth pipeline H39, and the outlet of the thirty-ninth pipeline H39 is divided into three branches: the fortieth pipeline H40, the forty-first pipeline H41, and the forty-second pipeline H42. The outlet of the fortieth pipeline H40 is connected to the inlet of the first alloy column D4, the outlet of the forty-first pipeline H41 is connected to the inlet of the second alloy column D5, and the outlet of the forty-second pipeline H42 is connected to the inlet of the third alloy column D6. The outlet of the first alloy column D4 is connected to the inlet of the forty-third pipeline H43, the outlet of the second alloy column D5 is connected to the inlet of the forty-fourth pipeline H44, and the outlet of the third alloy column D6 is connected to the inlet of the forty-fifth pipeline H45. The outlets of the forty-third pipeline H43, the forty-fourth pipeline H44, and the forty-fifth pipeline H45 converge to the inlet of the forty-sixth pipeline H46. After the helium gas is further dehydrogenated through the alloy column group, the outlet of the forty-sixth pipeline H46 is the helium gas product.
[0054] The bottom outlet of the liquid hydrogen separation tank D3 is connected to the liquid hydrogen storage tank through the thirty-seventh pipeline H37, forming a channel from the raw material gas to the liquid hydrogen product, and the liquid hydrogen product is obtained.
[0055] As Figure 2 shown, the hydrogen liquefaction cold box provided in this embodiment adopts a hydrogen-helium-neon mixed gas expansion refrigeration cycle, and the specific structure is as follows:
[0056] The inlet of the primary mixed gas compressor unit K4 receives the hydrogen-helium-neon mixed gas. Part of the hydrogen-helium-neon mixed gas comes from the tertiary heat exchanger HE3 in the hydrogen liquefaction cold box, and the other part comes from the refrigerant storage tanks including the hydrogen-helium-neon recovery tank D7, the hydrogen storage tank D8, the helium storage tank D9, and the neon storage tank D10. The composition of the hydrogen-helium-neon mixed gas can be adjusted.
[0057] The outlet of the primary mixed gas compressor unit K4 is connected to the inlet of the first mixed gas pipeline L1, and the outlet of the first mixed gas pipeline L1 is divided into two branches: the second mixed gas pipeline L2 and the third mixed gas pipeline L3.
[0058] The third mixed gas pipeline L3 of one branch is connected to the first hot side inlet of the three-stage heat exchanger HE3. The first hot side outlet of the three-stage heat exchanger HE3 is connected to the inlet of the first-stage expansion unit E1 through the sixth mixed gas pipeline L6. The outlet of the first-stage expansion unit E1 is connected to the fourth cold side inlet of the second-stage heat exchanger HE2 through the eleventh mixed gas pipeline L11. The fourth cold side outlet of the second-stage heat exchanger HE2 is connected to the fourth cold side inlet of the three-stage heat exchanger HE3 through the fourteenth mixed gas pipeline L14. The fourth cold side outlet of the three-stage heat exchanger HE3 is connected to the inlet of the seventeenth mixed gas pipeline L17 and then converges to the inlet of the eighteenth mixed gas pipeline L18.
[0059] The second mixed gas pipeline L2 of the other branch is connected to the inlet of the second-stage mixed gas compressor K5. The outlet of the second-stage mixed gas compressor K5 is provided with two branches, namely the fourth mixed gas pipeline L4 and the fifth mixed gas pipeline L5.
[0060] The outlet of the fourth mixed gas pipeline L4 is connected to the second hot side inlet of the three-stage heat exchanger HE3. The second hot side outlet of the three-stage heat exchanger HE3 is connected to the inlet of the second-stage expansion unit E2 through the seventh mixed gas pipeline L7. The outlet of the second-stage expansion unit E2 is connected to the third cold side inlet of the second-stage heat exchanger HE2 through the tenth mixed gas pipeline L10. The third cold side outlet of the second-stage heat exchanger HE2 is connected to the third cold side inlet of the three-stage heat exchanger through the thirteenth mixed gas pipeline L13. The third cold side outlet of the three-stage heat exchanger HE3 is connected to the inlet of the sixteenth mixed gas pipeline L16 and then converges to the inlet of the eighteenth mixed gas pipeline L18.
[0061] The outlet of the fifth mixed gas pipeline L5 is connected to the third hot side inlet of the three-stage heat exchanger HE3. The third hot side outlet of the three-stage heat exchanger HE3 is connected to the inlet of the third-stage expansion unit E3 through the eighth mixed gas pipeline L8. The outlet of the third-stage expansion unit E3 is connected to the second cold side inlet of the second-stage heat exchanger HE2 through the ninth mixed gas pipeline L9. The second cold side outlet of the second-stage heat exchanger HE2 is connected to the second cold side inlet of the three-stage heat exchanger through the twelfth mixed gas pipeline L12. The second cold side outlet of the three-stage heat exchanger HE3 is connected to the inlet of the fifteenth mixed gas pipeline L15 and then converges to the inlet of the eighteenth mixed gas pipeline L18.
[0062] The eighteenth mixed gas pipeline L18 receives the hydrogen-helium-neon mixed gas from the outlets of the fifteenth mixed gas pipeline L15 and the sixteenth mixed gas pipeline L16, as well as the hydrogen-helium-neon mixed gas from the refrigerant storage tank, constituting a hydrogen-helium-neon mixed gas expansion refrigeration cycle.
[0063] Since the primary heat exchanger HE1, secondary heat exchanger HE2, and tertiary heat exchanger HE3 in this embodiment are all disposed in the cold box, considering the low-temperature working conditions, in this embodiment, the primary heat exchanger HE1, secondary heat exchanger HE2, and tertiary heat exchanger HE3 are all aluminum plate-fin heat exchangers. The aluminum plate-fin heat exchanger can efficiently complete heat exchange in a low-temperature environment. In addition, the aluminum plate-fin heat exchanger has a compact structure design, small volume, and light weight, which can save the space of the device. Among them, in the product gas channel of the secondary heat exchanger HE2, ortho-para hydrogen conversion catalysts with corresponding temperature zone catalytic performance are filled along the fluid flow direction of the channel.
[0064] This embodiment also provides a method for preparing helium and liquid hydrogen by using the above-mentioned natural gas flash vapor stripping helium and co-producing liquid hydrogen device. The steps are as follows:
[0065] (1) The natural gas from upstream compression and purification first enters the primary heat exchanger HE1 in the LNG liquefaction cold box through the first pipeline H1 for heat exchange, and after cooling to the liquefaction temperature, it exits the LNG liquefaction cold box through the second pipeline H2. Subsequently, the BOG enters the primary heat exchanger HE1 in the LNG liquefaction cold box again through the third pipeline H3 for heat exchange. The heat-exchanged BOG then passes through the nitrogen removal tower cold box, membrane separation hydrogen and helium unit, helium recovery unit, and PSA refined hydrogen and helium unit to obtain a 99.999% high-purity hydrogen-helium mixed gas, which enters the primary heat exchanger HE1 through the thirty-first pipeline H31 for heat exchange, and cools down to -160 to -170 °C. Then it enters the secondary heat exchanger HE2 in the hydrogen liquefaction cold box through the thirty-third pipeline H33 for heat exchange. At the same time, under the action of the catalyst filled in the secondary heat exchanger HE2, the ortho-hydrogen content is increased from 25% to more than 97%. Then it passes through the throttle valve V1 for throttling and pressure reduction to 0.1 to 0.2 MPa and cools down to -263 to -268 °C. Finally, it enters the liquid hydrogen separation tank D3 for gas-liquid separation. The liquid hydrogen flows out from the bottom outlet of the liquid hydrogen separation tank D3 and enters the liquid hydrogen storage tank through the thirty-seventh pipeline H37, while the gas phase part flows out from the top outlet of the liquid hydrogen separation tank D3, is reheated in the secondary heat exchanger HE2 through the thirty-sixth pipeline H36, and then is reheated in the tertiary heat exchanger HE3 through the thirty-eighth pipeline H38 and enters the alloy dehydrogenation unit for dehydrogenation to obtain 99.9995% helium.
[0066] Among them, the mixed refrigerant refrigeration cycle technology is adopted in the LNG liquefaction cold box.
[0067] (2) In the hydrogen liquefaction cold box, hydrogen-helium-neon mixed gas expansion refrigeration is adopted. The inlet of the primary mixed gas compressor unit K4 receives the hydrogen-helium-neon mixed gas through the eighteenth mixed gas pipeline L18, and the outlet is connected to the inlet of the first mixed gas pipeline L1. The outlet of the first mixed gas pipeline L1 is divided into two branches, namely the second mixed gas pipeline L2 and the third mixed gas pipeline L3.
[0068] The mixed gas in the third mixed gas pipeline L3 enters the first hot side inlet of the tertiary heat exchanger HE3. After heat exchange, it is connected to the first-stage expansion unit E1 through the sixth mixed gas pipeline L6. After the mixed gas expands and cools down, it is connected to the fourth cold side inlet of the secondary heat exchanger HE2 through the eleventh mixed gas pipeline L11. After heat exchange in the secondary heat exchanger HE2, it is connected to the fourth cold side inlet of the tertiary heat exchanger through the fourteenth pipeline H14. After heat exchange in the tertiary heat exchanger HE3, it leaves the tertiary heat exchanger HE3 through the seventeenth pipeline H17.
[0069] The mixed gas in the second mixed gas pipeline L2 is compressed by the secondary mixed gas compressor K5 and then divided into two branches: the fourth mixed gas pipeline L4 and the fifth mixed gas pipeline L5.
[0070] The mixed gas in the fourth mixed gas pipeline L4 is heat-exchanged in the tertiary heat exchanger HE2 and then enters the second-stage expansion unit E2 to expand and cool down. The mixed gas at the outlet of the second-stage expansion unit E2 enters the secondary heat exchanger HE2 through the tenth mixed gas pipeline L10 for heat exchange, and then enters the third cold side of the tertiary heat exchanger HE3 through the thirteenth mixed gas pipeline L13. After heat exchange, it leaves the tertiary heat exchanger through the sixteenth pipeline H16. The mixed gas in the fifth mixed gas pipeline L5 is heat-exchanged in the tertiary heat exchanger HE2 and then enters the third-stage expansion unit E3 to expand and cool down. Then it enters the second cold side of the secondary heat exchanger HE2 through the ninth mixed gas pipeline L9. After heat exchange, it passes through the tertiary heat exchanger HE3 through the twelfth pipeline H12 for heat exchange and leaves the tertiary heat exchanger HE3 through the fifteenth pipeline H15.
[0071] The mixed gas in the fifteenth mixed gas pipeline L15, the sixteenth mixed gas pipeline L16 and the seventeenth mixed gas pipeline L17 converges into the eighteenth mixed gas pipeline L18, and then enters the first-stage compressor K4 through the eighteenth mixed gas pipeline L18 to form a cycle.
[0072] The hydrogen-helium-neon mixed gas in the eighteenth mixed gas pipeline L18 comes from the hydrogen-helium-neon recovery tank D7, the hydrogen storage tank D8, the helium storage tank D9 and the neon storage tank D10. The hydrogen-helium-neon mixed gas consists of 20 - 30 mol% hydrogen, 55 - 65 mol% helium and 10 - 20 mol% neon. The pressure in the hydrogen-helium-neon mixed gas expansion refrigeration cycle is divided into three levels: 2 - 2.5 MPa, 0.8 - 0.9 MPa and 0.3 - 0.4 MPa.
[0073] Using the helium production and liquid hydrogen co-production device for natural gas flash vapor provided by the present invention, the natural gas from upstream compression and purification enters the LNG storage tank after refrigeration in the LNG liquefaction cold box. The flash vapor of the LNG storage tank enters the hydrogen liquefaction cold box after reheating and purification and then after being refrigerated by the mixed refrigerant in the LNG liquefaction cold box. It is further cooled through the expansion refrigeration cycle of the hydrogen-helium-neon mixed gas, and after throttling down to the liquefaction temperature, the gaseous helium is reheated and then the product helium gas is obtained through alloy dehydrogenation, and the liquid hydrogen enters the liquid hydrogen storage tank. According to the method provided by the present invention, helium gas with a purity not less than 99.9995% and liquid hydrogen products with a purity not less than 99.99% can be produced.
[0074] The helium production and hydrogen liquefaction co-production device provided by the present invention utilizes the LNG cold box to provide precooling refrigeration capacity for the separation of the hydrogen-helium mixed gas. Further, the hydrogen-helium-neon mixed gas refrigeration cycle is adopted to realize the separation of hydrogen and helium while producing liquid hydrogen. The specific energy consumption of the hydrogen-helium-neon expansion refrigeration cycle is lower than 6.0 kWh / kg of liquid hydrogen, which is much lower than the specific energy consumption of 11.9 - 13.8 kWh / kg of liquid hydrogen at the present stage. The deep cryogenic separation of hydrogen and helium greatly reduces the load of the alloy dehydrogenation unit and reduces the size of the alloy column. In addition, the hydrogen-helium-neon mixed gas refrigeration cycle avoids the use of large hydrogen / helium compressors and hydrogen / helium expanders. The sound speed of the hydrogen-helium-neon mixed gas with an average molecular weight of 6 - 8 g / mol is much lower than that of pure hydrogen / helium, reducing the manufacturing difficulty of the compressor and the expander.
[0075] The above-described embodiments are only a preferred solution of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can also make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by adopting equivalent substitution or equivalent transformation methods fall within the protection scope of the present invention.
Claims
1. A natural gas flash vapor helium extraction and liquid hydrogen co-production device, characterized in that, It includes an LNG liquefaction cold box, an LNG storage tank (D2), a hydrogen liquefaction cold box, a liquid hydrogen storage tank, a denitrification tower cold box, a helium recovery cold box, a membrane separation hydrogen and helium extraction unit, a PSA purified hydrogen and helium unit, and an alloy dehydrogenation unit; Among them, a primary heat exchanger (HE1) is provided in the LNG liquefaction cold box; the hydrogen liquefaction cold box includes a secondary heat exchanger (HE2), a tertiary heat exchanger (HE3), a throttle valve (V1), a liquid hydrogen separation tank (D3), and an expansion unit; the denitrification tower cold box includes a denitrification tower (T1), a denitrification tower reboiler (C1), and a BOG heat exchanger (C2); a helium recovery tank (D1) is provided in the helium recovery cold box; the membrane separation hydrogen and helium extraction unit includes a primary membrane (M1), a secondary membrane (M2), and an intermembrane compressor (K1); an adsorption tower group is provided in the PSA purified hydrogen and helium unit; an alloy column group is provided in the alloy hydrogen absorption unit; The LNG liquefaction cold box liquefies the natural gas from upstream compression and purification by using a mixed refrigerant cycle, so as to obtain LNG products and send them to the LNG storage tank (D2); the denitrification tower cold box receives the BOG volatilized from the LNG storage tank (D2), recovers the LNG therein, and sends the top gas to the membrane separation hydrogen and helium extraction unit and the PSA purified hydrogen and helium unit in sequence, so as to obtain a high-purity hydrogen and helium mixture gas with a purity not less than 99.999%; the hydrogen liquefaction cold box preliminarily separates the high-purity hydrogen and helium mixture gas by using the cooling capacity provided by the hydrogen, helium, and neon mixture gas expansion refrigeration cycle, so as to obtain liquid hydrogen products and helium gas with a purity not less than 99.9%; the alloy dehydrogenation unit adsorbs trace hydrogen in the helium gas, so as to obtain helium gas products with a purity not less than 99.9995%.
2. The helium production by flash vaporization of natural gas and co-production of liquid hydrogen device according to claim 1, characterized in that The specific structure is as follows: The natural gas from upstream compression and purification is connected to the first heat side inlet of the primary heat exchanger (HE1) through the first pipeline (H1); the first heat side outlet of the primary heat exchanger (HE1) is connected to the inlet of the LNG storage tank (D2) through the second pipeline (H2); the top outlet of the LNG storage tank (D2) is connected to the first cold side inlet of the primary heat exchanger (HE1) through the third pipeline (H3); The first cold side outlet of the primary heat exchanger (HE1) is sequentially connected to the inlet of the denitrification tower reboiler (C1) through the fourth pipeline (H4) and the fifth pipeline (H5); the outlet of the denitrification tower reboiler (C1) is connected to the middle inlet of the denitrification tower (T1) through the sixth pipeline (H6); the top outlet of the denitrification tower (T1) is connected to the inlet of the BOG heat exchanger (C2) through the seventh pipeline (H7); the bottom outlet of the denitrification tower (T1) is connected to the inlet of the LNG storage tank (D2) through the eighth pipeline (H8) to recover LNG; the outlet of the BOG heat exchanger (C2) is connected to the inlet of the ninth pipeline (H9), and the outlet of the ninth pipeline (H9) is divided into two branches, namely the tenth pipeline (H10) and the eleventh pipeline (H11); The inlet of the first-stage membrane (M1) is connected to the tenth pipeline (H10) through the twelfth pipeline (H12); the outlet of the first-stage membrane (M1) is sequentially connected to the inlet of the inter-membrane compressor (K1) through the thirteenth pipeline (H13) and the fourteenth pipeline (H14); the top outlet of the first-stage membrane (M1) is connected to the inlet of the helium recovery tank (D1) through the fifteenth pipeline (H15); the top outlet of the helium recovery tank (D1) converges with the outlet of the eleventh pipeline (H11) through the sixteenth pipeline (H16) to the inlet of the seventeenth pipeline (H17); the outlet of the seventeenth pipeline (H17) is connected to the inlet of the BOG compressor (K2); the outlet of the BOG compressor (K2) converges with the outlet of the fourth pipeline (H4) through the eighteenth pipeline (H18) to the inlet of the fifth pipeline (H5); the outlet of the inter-membrane compressor (K1) is connected to the inlet of the second-stage membrane (M2) through the nineteenth pipeline (H19); the outlet of the second-stage membrane (M2) is connected to the inlet of the crude helium compressor (K3) through the twentieth pipeline (H20); the top outlet of the second-stage membrane (M2) converges with the outlet of the tenth pipeline (H10) through the twenty-first pipeline (H21) to the inlet of the twelfth pipeline (H12). The outlet of the crude helium compressor (K3) is connected to the inlet of the twenty-second pipeline (H22), and the outlet of the twenty-second pipeline (H22) is divided into four branches: the twenty-third pipeline (H23), the twenty-fourth pipeline (H24), the twenty-fifth pipeline (H25), and the twenty-sixth pipeline (H26); the outlets of the twenty-third pipeline (H23), the twenty-fourth pipeline (H24), the twenty-fifth pipeline (H25), and the twenty-sixth pipeline (H26) are respectively connected to the inlets of the first adsorption tower (T2), the second adsorption tower (T3), the third adsorption tower (T4), and the fourth adsorption tower (T5); the outlets of the first adsorption tower (T2), the second adsorption tower (T3), the third adsorption tower (T4), and the fourth adsorption tower (T5) converge through the twenty-seventh pipeline (H27), the twenty-eighth pipeline (H28), the twenty-ninth pipeline (H29), and the thirtieth pipeline (H30) and are then divided into two branches: the thirty-first pipeline (H31) and the thirty-second pipeline (H32). The outlet of the thirty-second pipeline (H32) converges with the outlet of the thirteenth pipeline (H13) to the inlet of the fourteenth pipeline (H14); the outlet of the thirty-first pipeline (H31) is connected to the second hot-side inlet of the first heat exchanger (HE1), and the second hot-side outlet of the first heat exchanger (HE1) is connected to the first hot-side inlet of the second heat exchanger (HE2) through the thirty-third pipeline (H33); the first hot-side outlet of the second heat exchanger (HE2) is sequentially connected to the inlet of the liquid hydrogen separation tank (D3) through the thirty-fourth pipeline (H34), the throttle valve (V1), and the thirty-fifth pipeline (H35). The top outlet of the liquid hydrogen separation tank (D3) successively passes through the thirty-sixth pipeline (H36), the first cold-side inlet of the secondary heat exchanger (HE2), the first cold-side outlet of the secondary heat exchanger (HE2), the thirty-eighth pipeline (H38), the first cold-side inlet of the tertiary heat exchanger (HE3), the first cold-side outlet of the tertiary heat exchanger (HE3), and then is connected to the inlet of the thirty-ninth pipeline (H39). The outlet of the thirty-ninth pipeline (H39) is divided into three branches: the fortieth pipeline (H40), the forty-first pipeline (H41), and the forty-second pipeline (H42). The fortieth pipeline (H40), the forty-first pipeline (H41), and the forty-second pipeline (H42) are respectively connected to the inlets of the first alloy column (D4), the second alloy column (D5), and the third alloy column (D6). The outlets of the first alloy column (D4), the second alloy column (D5), and the third alloy column (D6) are respectively converged to the inlet of the forty-sixth pipeline (H46) through the forty-third pipeline (H43), the forty-fourth pipeline (H44), and the forty-fifth pipeline (H45). The outlet of the forty-sixth pipeline (H46) is the helium product. The bottom outlet of the liquid hydrogen separation tank (D3) is connected to the inlet of the liquid hydrogen storage tank through the thirty-seventh pipeline (H37) to obtain liquid hydrogen products.
3. The helium production by flash vaporization of natural gas and liquid hydrogen co-production device according to claim 2, wherein, The specific structure of the hydrogen-helium-neon mixed gas expansion refrigeration cycle is as follows: The inlet of the primary mixed gas compressor unit (K4) receives the hydrogen-helium-neon mixed gas from the eighteenth mixed gas pipeline (L18). The outlet of the primary mixed gas compressor unit (K4) is connected to the inlet of the first mixed gas pipeline (L1). The outlet of the first mixed gas pipeline (L1) is divided into two branches: the second mixed gas pipeline (L2) and the third mixed gas pipeline (L3). The outlet of the third mixed gas pipeline (L3) successively passes through the first hot-side inlet of the tertiary heat exchanger (HE3), the first hot-side outlet of the tertiary heat exchanger (HE3), the sixth mixed gas pipeline (L6), the primary expansion unit (E1), and the eleventh mixed gas pipeline (L11) and is connected to the fourth cold-side inlet of the secondary heat exchanger (HE2). The fourth cold-side outlet of the secondary heat exchanger (HE2) successively passes through the fourteenth mixed gas pipeline (L14), the fourth cold-side inlet of the tertiary heat exchanger (HE3), the fourth cold-side outlet of the tertiary heat exchanger (HE3), and the seventeenth mixed gas pipeline (L17) and then converges to the inlet of the eighteenth mixed gas pipeline (L18). The second mixed gas pipeline (L2) is connected to the inlet of the secondary mixed gas compressor unit (K5); the outlet of the secondary mixed gas compressor unit (K5) is divided into two branches, namely the fourth mixed gas pipeline (L4) and the fifth mixed gas pipeline (L5); the outlet of the fourth mixed gas pipeline (L4) sequentially passes through the second hot side inlet of the tertiary heat exchanger (HE3), the second hot side outlet of the tertiary heat exchanger (HE3), the seventh mixed gas pipeline (L7), the secondary expansion unit (E2), and the tenth mixed gas pipeline (L10) and is connected to the third cold side inlet of the secondary heat exchanger (HE2); the third cold side outlet of the secondary heat exchanger (HE2) sequentially passes through the thirteenth mixed gas pipeline (L13), the third cold side inlet of the tertiary heat exchanger (HE3), the third cold side outlet of the tertiary heat exchanger (HE3), and the sixteenth mixed gas pipeline (L16) and then converges to the inlet of the eighteenth mixed gas pipeline (L18); the outlet of the fifth mixed gas pipeline (L5) sequentially passes through the third hot side inlet of the tertiary heat exchanger (HE3), the third hot side outlet of the tertiary heat exchanger (HE3), the eighth mixed gas pipeline (L8), the tertiary expansion unit (E3), and the ninth mixed gas pipeline (L9) and is connected to the second cold side inlet of the secondary heat exchanger (HE2); the second cold side outlet of the secondary heat exchanger (HE2) sequentially passes through the twelfth mixed gas pipeline (L12), the second cold side inlet of the tertiary heat exchanger (HE3), the second cold side outlet of the tertiary heat exchanger (HE3), and the fifteenth mixed gas pipeline (L15) and then converges to the inlet of the eighteenth mixed gas pipeline (L18). The outlet of the eighteenth mixed gas pipeline (L18) is connected to the inlet of the primary mixed gas compressor unit (K4), forming a hydrogen-helium-neon mixed gas expansion refrigeration cycle.
4. The helium co-production and liquid hydrogen production device for natural gas flash vapor stripping according to claim 3, wherein There is also provided a refrigerant storage tank including a hydrogen-helium-neon recovery tank (D7), a hydrogen storage tank (D8), a helium storage tank (D9), and a neon storage tank (D10); the hydrogen-helium-neon recovery tank (D7), the hydrogen storage tank (D8), the helium storage tank (D9), and the neon storage tank (D10) are all connected to the eighteenth mixed gas pipeline (L18) through pipelines for adjusting the composition of the hydrogen-helium-neon mixed gas.
5. The helium production by flash vaporization of natural gas and liquid hydrogen co-production device according to claim 3, characterized in that, The LNG liquefaction cold box is an atmospheric pressure cold box, and the hydrogen liquefaction cold box is a vacuum cold box.
6. The helium production by flash vaporization of natural gas and liquid hydrogen co-production device according to claim 3, characterized in that, The primary heat exchanger (HE1), the secondary heat exchanger (HE2), and the tertiary heat exchanger (HE3) are all aluminum plate-fin heat exchangers. Among them, in the product gas channel of the secondary heat exchanger (HE2), ortho-para hydrogen conversion catalysts with corresponding temperature zone catalytic performance are filled along the fluid flow direction of the channel.
7. A method for preparing helium and liquid hydrogen by using the natural gas flash vapor stripping helium co-producing liquid hydrogen device according to any one of claims 4 to 6, characterized in that, Specifically as follows: The natural gas from upstream compression and purification enters the first-stage heat exchanger (HE1) in the LNG liquefaction cold box for heat exchange, and after being cooled to the liquefaction temperature, it exits the LNG liquefaction cold box and enters the LNG storage tank (D2); the BOG gas at the top of the LNG storage tank (D2) then enters the first-stage heat exchanger (HE1) in the LNG liquefaction cold box for heat exchange, and the BOG gas after heat exchange then passes through the denitrification tower cold box, membrane separation hydrogen and helium extraction unit, helium recovery unit, and PSA refined hydrogen and helium unit to obtain a high-purity hydrogen and helium mixture of 99.999%; after the high-purity hydrogen and helium mixture enters the first-stage heat exchanger (HE1) for heat exchange and is cooled to -160 to -170 °C, it then enters the second-stage heat exchanger (HE2) in the hydrogen liquefaction cold box for heat exchange. At the same time, under the action of the catalyst filled in the second-stage heat exchanger (HE2), the parahydrogen content is increased from 25% to over 97%. Then, it passes through the throttle valve (V1) for throttling and pressure reduction to 0.1 to 0.2 MPa while being cooled to -263 to -268 °C, and finally enters the liquid hydrogen separation tank (D3) for gas-liquid separation; the liquid hydrogen flows out from the bottom outlet of the liquid hydrogen separation tank (D3) and enters the liquid hydrogen storage tank, while the gas phase part flows out from the top outlet of the liquid hydrogen separation tank (D3), and after being reheated in the second-stage heat exchanger (HE2) and the third-stage heat exchanger (HE3) in sequence, it enters the alloy dehydrogenation unit for dehydrogenation to obtain helium with a purity of 99.9995%. In the hydrogen liquefaction cold box, hydrogen-helium-neon mixture expansion refrigeration is adopted: the inlet of the first-stage mixture compressor unit (K4) receives the hydrogen-helium-neon mixture from the third-stage heat exchanger (HE3) in the hydrogen liquefaction cold box; a part of the gas at the outlet of the first-stage mixture compressor unit (K4) flows back to the first-stage mixture compressor unit (K4) in sequence through the first-stage expansion unit (E1), the second-stage heat exchanger (HE2), and the third-stage heat exchanger (HE3); the remaining gas at the outlet of the first-stage mixture compressor unit (K4) is compressed by the second-stage mixture compressor unit (K5), and a part of it flows back to the first-stage mixture compressor unit (K4) in sequence through the second-stage expansion unit (E2), the second-stage heat exchanger (HE2), and the third-stage heat exchanger (HE3), and another part of it flows back to the first-stage mixture compressor unit (K4) in sequence through the third-stage expansion unit (E3), the second-stage heat exchanger (HE2), and the third-stage heat exchanger (HE3), forming a hydrogen-helium-neon mixture expansion refrigeration cycle; the first-stage mixture compressor unit (K4) also receives the hydrogen-helium-neon mixture after mixing from the hydrogen-helium-neon recovery tank (D7), the hydrogen storage tank (D8), the helium storage tank (D9), and the neon storage tank (D10).
8. The method according to claim 7, wherein In the LNG liquefaction cold box, a mixed refrigerant cycle technology is adopted.
9. The method according to claim 7, wherein The hydrogen-helium-neon mixture consists of 20 - 30 mol% hydrogen, 55 - 65 mol% helium, and 10 - 20 mol% neon; in the hydrogen-helium-neon mixture expansion refrigeration cycle, the pressure is divided into three levels: 2 - 2.5 MPa, 0.8 - 0.9 MPa, and 0.3 - 0.4 MPa.
10. The method according to claim 7, wherein The crude helium compressor (K3) pressurizes the hydrogen-helium mixture to 2.0 - 2.5 MPa.