Device for producing high-purity helium from natural gas

Abstract

The invention discloses a device for producing high-purity helium from natural gas, which is characterized in that a natural gas drying and dehydrating unit is used for drying and dehydrating raw material natural gas and then outputting dry natural gas, and a crude helium cryogenic extraction cold box unit is used for conveying the dry natural gas into a first heat exchanger for cooling through an inlet channel arranged on a purification cold box main body; methane component purification and enrichment and helium primary concentration are carried out through the demethanization tower, gas-liquid separation is carried out in the gas-liquid separation tank after cooling is carried out through the second heat exchanger, liquid obtained after gas-liquid separation enters the helium crude extraction tower, and concentrated helium is output after secondary concentration is carried out; the method comprises the following steps: carrying out gas-liquid separation in a gas-liquid separation tank to obtain gas, further purifying the gas in a helium concentration tower, carrying out dehydrogenation treatment and dehydration treatment, carrying out nitrogen removal and concentration treatment through a pressure swing adsorption purification unit, and outputting high-concentration helium, so that helium can be extracted from helium-containing natural gas, the efficiency is high, the device integration degree is high, and the cost is low. And the user cost caused by nitrogen is reduced.

Description

Technical Field

[0001] The invention relates to the fields of cryogenic gas separation and special gas separation technology, and in particular to a device for producing high-purity helium from natural gas. Background Art

[0002] Helium is an irreplaceable, scarce strategic resource that is related to national security and the development of high-tech industries. It has a wide range of uses in high-tech fields such as military industry, petrochemicals, aerospace, nuclear industry, deep-sea diving, and cryogenic science. The demand for helium is currently increasing at a rate of more than 10% each year.

[0003] my country's helium reserves are small and the sources are limited. According to the different helium extraction media, the traditional helium extraction methods are mainly divided into four methods: natural gas separation method, synthetic ammonia method, air method and uranium ore method. However, since the raw gas for helium extraction in the synthetic ammonia method and the air method usually contains a large amount of low-boiling impurity gases such as hydrogen and neon, and the proportion of helium in the air is only 0.0004%-0.00056%, and uranium ore is radioactive and toxic and difficult to mine, helium-containing natural gas is still the only source of industrial helium production so far.

[0004] Helium-containing natural gas is not evenly distributed around the world. North America, North Africa and Russia are rich in helium resources, accounting for more than 90% of the world's total helium reserves. my country's helium resources are very scarce, accounting for only 2.12% of the world's total, and the helium content in the natural gas produced is generally low, making helium extraction difficult and purification cost high.

[0005] In the traditional natural gas helium extraction process, it is divided into two categories according to the temperature during the extraction process: non-cryogenic method and cryogenic method. The non-cryogenic method mainly includes physical adsorption, solvent absorption, membrane separation and pressure swing adsorption (PSA). The cryogenic method is also called cryogenic method, which uses the different critical temperatures of each component in natural gas to achieve the separation and purification of helium. The non-cryogenic method is usually suitable for helium extraction when the impurity content in the raw natural gas is low or the helium concentration is high. Otherwise, it is difficult to obtain a high-purity helium product. In contrast, the cryogenic method has the advantages of high product purity and high yield. Therefore, the cryogenic method is the most widely used helium extraction method.

[0006] At present, the helium content of natural gas is extremely low (about 400ppm) and the nitrogen content in natural gas in some areas is relatively high. Therefore, the helium extraction process needs to process a large amount of natural gas and focus on the removal, recovery and utilization of nitrogen. On the other hand, similar technologies generally have the problem of low process integration and the need for a large amount of external refrigeration. Overall, their economic benefits are poor. In addition, the domestic cryogenic helium extraction process is mainly used for BOG helium extraction, with a small processing capacity, small equipment scale, and a large amount of external refrigeration required in the process flow, resulting in high energy consumption. Overall, domestic natural gas helium extraction technology is still at a relatively backward level, and its application is limited by the composition of raw natural gas, so its industrial application performance is small. Summary of the invention

[0007] The purpose of the present invention is to provide a natural gas production of high-purity helium device, which can purify helium from raw natural gas, and the helium product has high purity, low energy consumption, and can be produced continuously on a large scale.

[0008] In order to solve the above technical problems, an embodiment of the present invention provides a device for producing high-purity helium from natural gas, comprising:

[0009] The natural gas drying and dehydration unit is used to dry and dehydrate the raw natural gas and then output dry natural gas;

[0010] A crude helium deep cold extraction cold box unit is connected to the natural gas drying and dehydration unit, and comprises a purification cold box body and a first heat exchanger, a second heat exchanger, a third heat exchanger, a demethanizer, a helium crude stripping tower, a helium concentration tower and a gas-liquid separation tank arranged in the purification cold box body. The dry natural gas is transported to the first heat exchanger through an inlet channel arranged in the purification cold box body for cooling, and then enters the demethanizer for methane component purification and enrichment and helium primary concentration, and outputs a first concentrated gas after helium primary concentration. The first concentrated gas is cooled by the second heat exchanger and then subjected to gas-liquid separation in the gas-liquid separation tank. The liquid after gas-liquid separation enters the helium crude stripping tower, and after secondary concentration in the helium crude stripping tower, the concentrated helium is output at the top of the helium crude stripping tower. The gas obtained after the first concentrated gas is subjected to gas-liquid separation in the gas-liquid separation tank and the concentrated helium is further purified in the helium concentration tower, and then a crude helium product is output at the top of the helium concentration tower;

[0011] A catalytic dehydrogenation unit, used for receiving and performing dehydrogenation treatment on the crude helium product;

[0012] A drying and dehydration unit, used for dehydrating the crude helium product after the dehydrogenation operation;

[0013] The pressure swing adsorption purification unit is used to remove nitrogen from the crude helium product after dehydration treatment through an adsorbent filled in an adsorber to concentrate the product and then output helium.

[0014] It also includes a low-temperature adsorption unit and a helium liquefaction unit connected to the output end of the pressure swing adsorption purification unit. The low-temperature adsorption unit is used to produce high-purity helium after low-temperature adsorption operation of the helium produced by the pressure swing adsorption purification unit, and the helium liquefaction unit is used to liquefy the helium produced by the pressure swing adsorption purification unit to produce a high-purity liquid helium product.

[0015] Among them, it also includes a helium concentration tower condenser arranged in the upper inner cavity of the helium concentration tower, the helium concentration tower condenser is connected to a nitrogen refrigeration system, the nitrogen refrigeration system is used to provide cold capacity for the helium concentration tower condenser for refrigeration, the nitrogen refrigeration system is a liquid nitrogen supply system or a nitrogen circulation system, the nitrogen circulation system includes a nitrogen compressor subsystem and a circulating nitrogen heat exchanger, the nitrogen compressor subsystem, the circulating nitrogen heat exchanger and the helium concentration tower condenser are connected to form a closed cycle, providing cold capacity for the helium concentration tower, the high-pressure nitrogen generated by the nitrogen compressor subsystem is input into the circulating nitrogen heat exchanger for heat exchange cooling, and then provides cold capacity for the helium concentration tower condenser, and the low-temperature nitrogen output after heat exchange recovers cold capacity through the circulating nitrogen heat exchanger and then returns to the nitrogen compressor subsystem, forming a closed nitrogen cycle.

[0016] Among them, it also includes a cold insulation layer filled in the gap between the purification cold box body and the first heat exchanger, the second heat exchanger and the third heat exchanger, the demethanizer, the helium crude stripping tower, the helium concentration tower, and the gas-liquid separation tank. The purification cold box body is a steel structure purification cold box body, and the cold insulation layer is an aerogel cold insulation felt, a polyurethane cold insulation layer, a rubber cold insulation layer or a rock wool cold insulation layer.

[0017] It also includes a molecular sieve adsorber arranged in the natural gas drying and dehydration unit, which is used to obtain and output the dry natural gas by adsorbing the easily condensable components in the raw natural gas, and the adsorbent of the molecular sieve adsorber includes at least one of an alumina adsorbent, an activated carbon adsorbent, and a molecular sieve adsorbent.

[0018] Among them, it also includes an external compressor system arranged outside the purification cold box body and connected to the first heat exchanger, the second heat exchanger, the third heat exchanger, the demethanizer, and the helium crude stripping tower, which is used to compress the natural gas product obtained in the separation and purification process to the required pressure and discharge it from the purification cold box body through a pipeline to return to the natural gas network as a pipeline natural gas product.

[0019] Among them, the reboiler of the demethanizer, the reboiler of the helium crude stripping tower, the reboiler of the helium concentration tower, the condenser of the helium concentration tower, and the heat exchanger of the circulating nitrogen heat exchanger are plate-fin heat exchangers, the reboiler of the demethanizer, the reboiler of the helium crude stripping tower, the reboiler of the helium concentration tower and the condenser of the helium concentration tower are placed inside the distillation tower, and the demethanizer, the helium crude stripping tower and the helium concentration tower are structured packing towers, bulk packing towers or plate towers.

[0020] Among them, the first heat exchanger, the second heat exchanger, and the third heat exchanger are plate-fin heat exchangers, shell-and-tube heat exchangers, plate heat exchangers, shell and tube heat exchangers, spiral plate heat exchangers, heat pipe heat exchangers, or jacketed heat exchangers, and the first heat exchanger, the second heat exchanger, and the third heat exchanger have multiple heat exchange channels.

[0021] It also includes a temperature display and a parameter setter, the temperature display is used to display the inlet temperature, outlet temperature and air pressure of the first heat exchanger, the second heat exchanger and the third heat exchanger, and the parameter setter is used to set the operating temperature range of the first heat exchanger, the second heat exchanger and the third heat exchanger.

[0022] Wherein, it also includes an alarm for issuing an alarm message after the actual operating temperature of the first heat exchanger, the second heat exchanger, and the third heat exchanger exceeds the set operating temperature range.

[0023] The device for producing high-purity helium from natural gas provided in the embodiment of the present invention has the following advantages compared with the prior art:

[0024] The high-purity helium production device of natural gas provided by the embodiment of the present invention outputs dry natural gas after drying and dehydrating the raw natural gas through the natural gas drying and dehydration unit, and the crude helium deep cold extraction cold box unit transports the dry natural gas to the first heat exchanger for cooling through the inlet channel arranged in the purification cold box body, and then passes through the demethanizer to purify and enrich the methane component and concentrate the helium once, and then passes through the second heat exchanger for cooling and performs gas-liquid separation in the gas-liquid separation tank, and the liquid after the gas-liquid separation enters the helium crude extraction tower, and outputs the concentrated helium after the secondary concentration, and then passes through the gas-liquid separation in the gas-liquid separation tank. The gas and the concentrated helium are further purified in the helium concentration tower, and then the catalytic dehydrogenation unit performs dehydrogenation treatment and the drying and dehydration unit performs dehydration treatment, and finally the pressure swing adsorption purification unit removes nitrogen and concentrates the gas and outputs high-concentration helium. The device in the present application can extract helium from natural gas containing helium, and has the advantages of high efficiency, high device integration, high purity of helium products, low energy consumption, and continuous large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic structural diagram of an embodiment of a device for producing high-purity helium from natural gas provided by the present invention;

[0027] Figure 2 A schematic structural diagram of another embodiment of the device for producing high-purity helium from natural gas provided by the present invention;

[0028] Figure 3 A schematic diagram of the structure of a cold box unit for deep cold extraction of crude helium in one embodiment of the device for producing high-purity helium from natural gas provided by the present invention;

[0029] Figure 4 A schematic diagram of the structure of a nitrogen circulation system of an embodiment of a natural gas production high-purity helium device provided by the present invention;

[0030] Among them, 10-natural gas drying and dehydration unit, 20-crude helium deep cold extraction cold box unit, 21-first heat exchanger, 22-second heat exchanger, 23-third heat exchanger, 24-demethanizer, 25-helium crude extraction tower, 26-helium concentration tower, 27-gas-liquid separation tank, 30-catalytic dehydrogenation unit, 261-helium concentration tower condenser, 40-drying and dehydration unit, 50-pressure swing adsorption purification unit, 60-low temperature adsorption unit, 70-helium liquefaction unit, 80-external compressor system, 90-nitrogen circulation system, 91-nitrogen compressor subsystem, 92-the circulating nitrogen heat exchanger. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Please refer to Figure 1-Figure 4 , Figure 1 A schematic structural diagram of an embodiment of a device for producing high-purity helium from natural gas provided by the present invention; Figure 2 A schematic structural diagram of another embodiment of the device for producing high-purity helium from natural gas provided by the present invention; Figure 3A schematic diagram of the structure of a cold box unit for deep cold extraction of crude helium in one embodiment of the device for producing high-purity helium from natural gas provided by the present invention; Figure 4 This is a schematic structural diagram of a nitrogen circulation system of an embodiment of a device for producing high-purity helium from natural gas provided by the present invention.

[0033] In a specific embodiment, the natural gas production high purity helium device comprises:

[0034] The natural gas drying and dehydration unit 10 is used to dry and dehydrate the raw natural gas and then output dry natural gas;

[0035] The crude helium deep cold extraction cold box unit 20 is connected to the natural gas drying and dehydration unit 10, and includes a purification cold box body and a first heat exchanger 21, a second heat exchanger 22, a third heat exchanger 23, a demethanizer 24, a helium crude extraction tower 25, a helium concentration tower 26 and a gas-liquid separation tank 27 arranged in the purification cold box body. The dry natural gas is transported to the first heat exchanger 21 through the inlet channel arranged in the purification cold box body for cooling, and then enters the demethanizer 24 for methane group and enters the demethanizer for methane component purification and enrichment and helium The gas is concentrated once, and a first concentrated gas after the helium is concentrated once is output, the first concentrated gas is cooled by the second heat exchanger 22, and then gas-liquid separation is performed in the gas-liquid separation tank, the liquid after gas-liquid separation enters the helium crude stripping tower, and is concentrated twice in the helium crude stripping tower, and then the concentrated helium is output at the top of the helium crude stripping tower 25, the gas obtained after the first concentrated gas is separated by gas-liquid in the gas-liquid separation tank 27 and the concentrated helium are further purified in the helium concentration tower 26, and then a crude helium product is output at the top of the helium concentration tower;

[0036] A catalytic dehydrogenation unit 30, for receiving and performing dehydrogenation treatment on the crude helium product;

[0037] A drying and dehydration unit 40 is used to dehydrate the crude helium product after the dehydrogenation operation is completed;

[0038] The pressure swing adsorption purification unit 50 is used to remove nitrogen from the crude helium product after dehydration treatment through an adsorbent filled in an adsorber and then output helium.

[0039] The raw natural gas is dried and dehydrated by the natural gas drying and dehydration unit 10 and then outputted as dry natural gas. The crude helium deep cold extraction cold box unit 20 delivers the dry natural gas to the first heat exchanger 21 through the inlet channel arranged in the purification cold box body for cooling. The dry natural gas is then purified and enriched by the methane component and concentrated by the helium through the demethanizer 24. The gas-liquid separation is then carried out in the gas-liquid separation tank 27 after cooling by the second heat exchanger 22. The liquid after the gas-liquid separation enters the helium crude extraction tower 25 and is concentrated twice before outputting the concentrated helium. The gas obtained after the gas-liquid separation with the primary concentrated helium through the gas-liquid separation tank 27 is further purified in the helium concentration tower 26. After that, the catalytic dehydrogenation unit 30 performs dehydrogenation treatment and the drying and dehydration unit 40 performs dehydration treatment. Finally, the pressure swing adsorption purification unit 50 removes nitrogen and concentrates the gas and then outputs high-concentration helium. Helium is efficiently extracted from the natural gas containing helium. The efficiency is high, the device integration is high, the purity of the helium product is high, the energy consumption is low, and continuous large-scale production is possible.

[0040] In order to meet the requirements of different products, in one embodiment, the natural gas high-purity helium production device also includes a low-temperature adsorption unit 60 and a helium liquefaction unit 70 connected to the output end of the pressure swing adsorption purification unit 50, wherein the low-temperature adsorption unit 60 is used to produce high-purity helium after low-temperature adsorption operation of the helium produced by the pressure swing adsorption purification unit 50, and the helium liquefaction unit 70 is used to liquefy the helium produced by the pressure swing adsorption purification unit 50 to produce a high-purity liquid helium product.

[0041] The helium produced by the pressure swing adsorption purification unit 50 is subjected to low-temperature adsorption operation by the low-temperature adsorption unit 60 to produce high-purity helium. The helium liquefaction unit 70 liquefies the helium produced by the pressure swing adsorption purification unit 50 to produce a high-purity liquid helium product. Liquid or gaseous helium products can be obtained to meet different usage needs.

[0042] The present application includes but is not limited to using a cryogenic adsorption unit 60 and a helium liquefaction unit 70 to obtain the final product, and there is no limitation on the structure thereof.

[0043] In order to improve the refrigeration efficiency in the present application, in one embodiment, the natural gas production high-purity helium device also includes a helium concentration tower condenser arranged in the upper inner cavity of the helium concentration tower 26, and the helium concentration tower condenser 261 is connected to a nitrogen refrigeration system, and the nitrogen refrigeration system is used to provide cold capacity for the helium concentration tower 26 condenser for refrigeration. The nitrogen refrigeration system is a liquid nitrogen supply system or a nitrogen circulation system 90, and the nitrogen circulation system 90 includes a nitrogen compressor subsystem 91 and a circulating nitrogen heat exchanger 9 2. The nitrogen compressor subsystem 91, the circulating nitrogen heat exchanger 92 and the helium concentration tower condenser 261 are connected to form a closed cycle to provide cooling for the helium concentration tower 26. The high-pressure nitrogen generated by the nitrogen compressor subsystem 91 is input into the circulating nitrogen heat exchanger 92 for heat exchange cooling to provide cooling for the helium concentration tower condenser 261. The low-temperature nitrogen output after heat exchange is returned to the nitrogen compressor subsystem 91 after recovering cooling through the circulating nitrogen heat exchanger 92, thereby forming a closed nitrogen cycle.

[0044] By setting up a nitrogen refrigeration system, low-temperature nitrogen is used for refrigeration, and a nitrogen circulation system 90 is used as a refrigeration system. Through a nitrogen compressor subsystem 91 and a circulating nitrogen heat exchanger 92, the nitrogen compressor subsystem 91 and the circulating nitrogen heat exchanger 92 are connected with the helium concentration tower condenser 261 to form a closed cycle. After providing cold for the helium concentration tower condenser 261, the low-temperature nitrogen output is returned to the nitrogen compressor subsystem after recovering cold through the circulating nitrogen heat exchanger, thereby forming a closed nitrogen cycle. Cold recovery can be achieved, and the cold utilization efficiency in the operation of the liquid nitrogen system can be improved, energy consumption can be reduced, and operating costs can be reduced, and the increase in structural costs is relatively small.

[0045] In order to further reduce unnecessary heat exchange with the outside during the refrigeration process, reduce cold loss, and improve utilization efficiency, in one embodiment, the natural gas production of high-purity helium device also includes a cold insulation layer filled in the gap between the purification cold box body and the first heat exchanger 21, the second heat exchanger 22 and the third heat exchanger 23, the demethanizer 24, the helium crude stripping tower 25, the helium concentration tower 26, and the gas-liquid separation tank 27. The purification cold box body is a steel structure purification cold box body, and the cold insulation layer is an aerogel cold insulation felt, a polyurethane cold insulation layer, a rubber cold insulation layer or a rock wool cold insulation layer.

[0046] By filling and setting a cold insulation layer in the gaps between the purification cold box body and the first heat exchanger 21, the second heat exchanger 22 and the third heat exchanger 23, the demethanizer 24, the helium crude stripping tower 25, the helium concentration tower 26 and the gas-liquid separation tank 27, the cold energy in the internal heat exchange process will not leak to the outside, thereby improving the utilization efficiency. At the same time, rapid refrigeration can be ensured, and the temperature of the designated area can be quickly reduced to the predetermined temperature, thereby improving the refrigeration efficiency and reliability.

[0047] The material and filling method of the cold insulation layer are not limited in the present application, including but not limited to aerogel cold insulation felt, polyurethane cold insulation layer, rubber cold insulation layer, rock wool cold insulation layer.

[0048] In the present application, dehydration is required during the initial treatment of natural gas. There is no limitation on the dehydration method and structure used. Chemical dehydration or physical dehydration can be used. In one embodiment, the natural gas production high-purity helium device also includes a molecular sieve adsorber arranged in the natural gas drying and dehydration unit 10, which is used to obtain and output the dry natural gas by adsorbing the easily solidified components in the raw natural gas. The adsorbent of the molecular sieve adsorber includes at least one of an alumina adsorbent, an activated carbon adsorbent, and a molecular sieve adsorbent.

[0049] The present application does not limit the number and working mode of the molecular sieve adsorbers.

[0050] In order to further improve the utilization efficiency of gas and reduce air pollution, in one embodiment, the natural gas production high-purity helium device also includes an external compressor system 80 arranged outside the purification cold box body and connected to the first heat exchanger 21, the second heat exchanger 22, the third heat exchanger 23, the demethanizer 24, and the helium crude stripping tower 25, which is used to compress the natural gas product obtained in the separation and purification process to a required pressure and discharge it from the purification cold box body through a pipeline to return to the natural gas network as a pipeline natural gas product.

[0051] By providing an external compressor system 80, the natural gas product obtained during the separation and purification process is compressed to a desired pressure and discharged through a pipeline from the purification cold box body as a pipeline natural gas product back to the natural gas network, so that the natural gas generated during helium purification can be recovered and processed, thereby reducing the overall helium extraction cost.

[0052] The present application does not limit the structure of the external compressor system 80 and the compression output pressure.

[0053] In order to further improve the utilization efficiency of heat, in one embodiment, the reboiler of the demethanizer 24, the reboiler of the helium crude stripping tower 25, the reboiler of the helium concentration tower 26, the condenser of the helium concentration tower 26, and the heat exchanger of the circulating nitrogen heat exchanger are plate-fin heat exchangers, the reboiler of the demethanizer 24, the reboiler of the helium crude stripping tower 25, the reboiler of the helium concentration tower 26 and the condenser of the helium concentration tower 26 are placed inside the distillation tower, and the demethanizer 24, the helium crude stripping tower 25 and the helium concentration tower 26 are structured packing towers, bulk packing towers or plate towers.

[0054] The present application does not limit the structure and location of the reboiler. The reboiler is used to provide heat to the corresponding device to achieve precise control of the temperature of the corresponding equipment.

[0055] The present application does not limit the number and structure of the heat exchangers, and the staff can increase or decrease the number of heat exchangers as needed. In one embodiment, the first heat exchanger 21, the second heat exchanger 22, and the third heat exchanger 23 are plate-fin heat exchangers, shell-and-tube heat exchangers, plate heat exchangers, shell and tube heat exchangers, spiral plate heat exchangers, heat pipe heat exchangers, or jacketed heat exchangers, and the first heat exchanger 21, the second heat exchanger 22, and the third heat exchanger 23 have multiple heat exchange channels.

[0056] The number of heat exchange channels is not limited in this application.

[0057] In order to further improve management efficiency, in one embodiment, the natural gas high-purity helium production device also includes a temperature display and a parameter setter, the temperature display is used to display the inlet temperature, outlet temperature and gas pressure of the first heat exchanger 21, the second heat exchanger 22, and the third heat exchanger 23, and the parameter setter is used to set the operating temperature range of the first heat exchanger 21, the second heat exchanger 22, and the third heat exchanger 23.

[0058] Through the temperature display and parameter setter, the temperature of the equipment can be accurately controlled, and flexible switching and adaptation of different processes can be achieved, which improves management efficiency and work efficiency.

[0059] In order to improve maintenance efficiency, in one embodiment, the natural gas production of high-purity helium device also includes an alarm for issuing an alarm message after the actual operating temperature of the first heat exchanger 21, the second heat exchanger 22, and the third heat exchanger 23 exceeds a set operating temperature range.

[0060] By sending out an alarm message when the actual operating temperature of the first heat exchanger 21, the second heat exchanger 22, and the third heat exchanger 23 exceeds the set operating temperature range, the actual heat exchange temperature can be accurately controlled to improve the reliability of the process.

[0061] The present application does not limit the structure of the alarm and the alarm mode, which may be a sound alarm, a light alarm, or other alarm modes.

[0062] In one embodiment, a natural gas high-purity helium production device uses helium-poor nitrogen-rich natural gas to produce high-purity helium, including a natural gas drying and dehydration unit 10, a crude helium deep cold extraction cold box unit 20, a catalytic dehydrogenation unit 30, a helium drying and dehydration unit 40, a pressure swing adsorption purification unit 50, a cryogenic adsorption unit 60, a helium liquefaction unit 70 and an external compressor system 80, which are connected to each other through pipelines.

[0063] The natural gas from a mixture of methane, nitrogen, hydrogen, helium and carbon dioxide as raw materials is first sent to the natural gas drying and dehydration unit 10 through a pipeline as raw material gas. The molecular sieve adsorber of the natural gas drying and dehydration unit 10 is filled with molecular sieves to adsorb trace moisture and easily solidified components at low temperatures in the raw natural gas to prevent these substances from solidifying at low temperatures and clogging pipelines and equipment. The purified dry natural gas enters the crude helium deep cold purification cold box unit through a pipeline.

[0064] The crude helium deep-cold purification cold box unit is generally integrated and includes the first, second and third main fin heat exchangers with multiple heat exchange channels, a demethanizer 24, a helium crude stripping tower 25, a helium concentration tower 26, a gas-liquid separation tank 27, and pipes and valves required for equipment connection. These equipment, pipes and valves are all placed in the cold box steel structure, and the gaps in the cold box are filled with cold insulation materials for cold preservation.

[0065] The crude helium cryogenic purification cold box delivers the raw natural gas to the first main plate fin heat exchanger through the inlet channel, and after cooling in the heat exchange channel, it is connected to the demethanizer 24 reboiler in the inner cavity at the bottom of the demethanizer 24 through a pipeline to provide reboiling heat for the demethanizer 24. The raw natural gas returned to the first main plate fin heat exchanger continues to cool and enters the middle inlet of the demethanizer 24 through a pipeline, where the methane component is purified and enriched and the helium is concentrated once.

[0066] A demethanizer 24 reboiler is provided in the lower inner cavity of the demethanizer 24 for heating the liquid at the bottom of the tower. The raw natural gas is connected to the reboiler through the first main plate fin heat exchanger and the pipeline for cooling and heat exchange to provide reboiling heat for the demethanizer 24, and further adjust the gas-liquid ratio of the demethanizer 24 to achieve efficient separation.

[0067] The primary helium concentrated product obtained by the tower separation is connected to the second main board fin-type heat exchanger through the tower top pipeline, and the primary concentrated helium is further cooled and connected to the gas-liquid separation tank 27 through the pipeline, and then the gas-liquid phase separation is carried out in the gas-liquid separation tank 27; the liquid methane product led out from the bottom of the demethanizer 24 through the pipeline is connected to the first main board fin-type heat exchanger through the throttle valve and the pipeline, and the reheated process gas is connected to the compressor system 80 outside the cold box through the pipeline. After the methane gas is compressed to a certain pressure in the compressor system, it is discharged from the cold box through the pipeline and returned to the natural gas pipeline network as a pipeline natural gas product.

[0068] The gas of the gas-liquid separation tank 27 is led out from the top channel, and the liquid led out from the bottom through the pipeline is connected to the middle inlet of the helium crude stripping tower 25, and then the helium is secondary concentrated in the helium crude stripping tower 25.

[0069] A reboiler of the helium crude stripping tower 25 is arranged in the lower inner cavity of the helium crude stripping tower 25, which is used for heating the liquid at the bottom of the tower. The intermediate product of the primary helium stripping is connected to the reboiler through the second main plate fin heat exchanger and the pipeline for cooling and heat exchange to provide reboiling heat for the helium crude stripping tower 25, and further adjust the gas-liquid ratio of the helium crude stripping tower 25 to achieve efficient separation.

[0070] The secondary helium enrichment product obtained by the helium crude stripping tower 25 is combined with the gas drawn out of the top pipeline of the gas-liquid separator through the top pipeline of the tower, and then connected to the third main board fin heat exchanger through the pipeline, and after further cooling, it is connected to the middle inlet of the helium concentration tower 26 through the pipeline, and then the crude helium is further enriched and purified in the helium concentration tower 26;

[0071] The liquid led out through the pipeline at the bottom of the helium crude stripping tower 25 is connected to the second main plate fin heat exchanger through a throttle valve and a pipeline, and recovers cold energy through the pipeline and the second and first main plate fin heat exchangers in turn, and then is connected to the compressor system 80 outside the cold box through a pipeline, compressed to a certain pressure in the compressor system, discharged from the cold box through the pipeline, and returned to the natural gas pipeline network as a pipeline natural gas product.

[0072] A helium concentration tower 26 condenser is provided in the upper inner cavity of the helium concentration tower 26 for condensing the gas at the top of the tower. The condenser is connected to the liquid nitrogen system through a pipeline to provide cold for the helium concentration tower 26. A helium concentration tower 26 reboiler is provided in the lower inner cavity of the helium concentration tower 26 for heating the liquid at the bottom of the tower. The secondary helium concentration product is connected to the reboiler through the third main plate fin heat exchanger and the pipeline for cooling and heat exchange to provide reboiling heat for the helium concentration tower 26, and further adjusts the gas-liquid ratio of the helium concentration tower 26 to achieve efficient separation. After the crude helium product obtained at the top of the tower is condensed and separated in the condenser, it is connected to the third main plate fin heat exchanger through a pipeline, and the cold is recovered through the pipeline and the third, second and first main plate fin heat exchangers in turn, and then sent out of the cold box through the pipeline to obtain a crude helium product.

[0073] A crude nitrogen product is obtained at the bottom of the helium concentration tower 26. The crude nitrogen drawn out through the pipeline is connected to the third main board fin heat exchanger through a throttle valve and a pipeline, and then recovers cold through the pipeline and the third, second and first main board fin heat exchangers in sequence, and then is discharged from the cold box through the pipeline to obtain a crude nitrogen product.

[0074] The liquid nitrogen system enters the crude helium deep-cold purification cold box through a pipeline and is connected to the condenser of the helium concentration tower 26. The liquid nitrogen after heat exchange with the crude helium product in the condenser is connected to the third main board fin heat exchanger through a pipeline. The low-pressure nitrogen after recovering cold through the pipeline and the third, second and first main board fin heat exchangers in sequence is discharged from the cold box through the pipeline and then vented at a high point.

[0075] The compressor system is connected to the crude helium deep-cold purification cold box through pipelines, and compresses the natural gas products separated and purified from the demethanizer 24 and the helium crude stripping tower 25 to the required pressure and discharges them from the cold box through pipelines to return to the natural gas network as pipeline natural gas products.

[0076] The crude helium gas purified by the crude helium deep-cold purification cold box is output from the cold box through a pipeline and enters the high-purity helium refining process.

[0077] In the high-purity helium refining process, the crude helium first enters the catalytic dehydrogenation unit 30, the internal reactor of the catalytic dehydrogenation unit 30 is filled with a catalytic dehydrogenation catalyst to remove hydrogen from the crude helium, and then the helium product from which hydrogen is removed is connected to the drying and dehydration unit 40 through a pipeline; the molecular sieve adsorber of the drying and dehydration unit 40 is filled with a molecular sieve to adsorb water vapor generated by the catalytic dehydrogenation reaction to prevent it from solidifying at low temperature and clogging the pipeline and equipment, and then the dried helium enters the PSA purification unit through a pipeline (optionally, the processing scale can be simplified by adding a low-temperature adsorption unit 60); the adsorber of the PSA purification unit is filled with an adsorbent to further remove nitrogen and other impurities in the helium to further concentrate the helium; the concentrated helium is divided into two branches: the first branch goes to the low-temperature adsorption unit 60 through a pipeline to further enrich the helium and produce high-purity helium to enter the storage device through a pipeline; the second branch goes to the helium liquefaction unit 70 through a pipeline to produce a high-purity liquid helium product and goes to the liquid helium storage device through a pipeline.

[0078] The main plate fin heat exchanger, the reboiler of the demethanizer 24, the reboiler of the helium crude stripping tower 25, the reboiler of the helium concentration tower 26, and the condenser of the helium concentration tower 26 in the crude helium deep cold purification cold box all adopt plate fin heat exchangers. The plate fin heat exchanger has the largest heat exchange area per unit volume, and can realize heat exchange of multiple streams at the same time, so that its heat exchange efficiency is maximized. The reboiler of the demethanizer 24, the reboiler of the helium crude stripping tower 25, the reboiler of the helium concentration tower 26, and the condenser of the helium concentration tower 26 are arranged inside the distillation tower, which can save the internal space of the cold box, reduce the volume of the cold box, and save construction costs. The demethanizer 24, the helium crude stripping tower 25, and the helium concentration tower 26 can use structured packing, bulk packing or plate tower, and the separation efficiency is high. The crude helium deep cold purification cold box adopts a steel structure cold box, and the cold box is filled with pearl sand cold insulation material for cold insulation. The structure is compact and convenient for skid transportation.

[0079] On the basis of the above embodiment, the crude helium cryogenic purification cold box unit can be deformed. Before the deformation, the upper inner cavity of the helium concentration tower 26 in the crude helium cryogenic purification cold box unit is provided with a helium concentration tower condenser 261, and the liquid nitrogen system provides cold for it; after the deformation, the cold of the helium concentration tower condenser 261 in the crude helium cryogenic purification cold box is provided by a nitrogen circulation refrigeration system 90. The nitrogen circulation refrigeration system 90 is composed of a nitrogen compressor system 91 outside the cold box and a circulating nitrogen heat exchanger 92, and is connected to the helium concentration tower condenser 261 to form a closed cycle, providing cold for the helium concentration tower 26. In the nitrogen circulation system 90, high-pressure nitrogen from the nitrogen compressor system 91 outside the cold box is connected to the circulating nitrogen heat exchanger 92 through a pipeline, and after being cooled in the heat exchange channel, enters the helium concentration tower condenser 261 through a pipeline to condense the crude helium at the top of the helium concentration tower. The nitrogen exiting the condenser is connected to the circulating nitrogen heat exchanger 92 through a pipeline, and after recovering its cold energy, it returns to the nitrogen compressor system 91 through a pipeline, forming a closed nitrogen refrigeration cycle to provide cold energy for the helium concentration tower.

[0080] The cryogenic purification cold box delivers the raw natural gas (pressure of about 2.0-4.0 MPaG) to the first main plate fin heat exchanger through the inlet channel, and after cooling in the heat exchange channel, it is connected to the demethanizer reboiler in the inner cavity at the bottom of the demethanizer through a pipeline to provide heat for the demethanizer. The logistics returning from the demethanizer reboiler to the first main plate fin heat exchanger continues to cool to about -120°C to -150°C and enters through the middle inlet channel of the demethanizer, where the methane component is purified and enriched and the helium is concentrated once.

[0081] The function of the first main plate fin heat exchanger is to exchange heat between the raw natural gas and the returned natural gas products, low-pressure nitrogen, crude helium, and crude nitrogen gas streams. On the one hand, the raw natural gas is pre-cooled, and on the other hand, the cold energy of the natural gas products, low-pressure nitrogen, crude helium, and crude nitrogen gas streams is recovered and discharged from the cold box at room temperature.

[0082] From the perspective of purifying helium, the role of the demethanizer is to remove the methane component from the raw material; from the perspective of recovering natural gas products, the role of the demethanizer is to purify and enrich methane at the bottom of the tower and to concentrate the helium component at the top of the tower. The demethanizer can purify helium on the one hand, and produce by-product natural gas, i.e. methane-rich gas, on the other hand.

[0083] The methane content of the liquid product at the bottom of the demethanizer is about 90% to 98%. After being drawn out through the bottom pipeline, it is connected to the first main board fin-type heat exchanger through a throttle valve and a pipeline. After recovering its cold capacity, it is connected to the compressor system outside the cold box through a pipeline. After being compressed to a certain pressure, it returns to the natural gas pipeline network as a pipeline natural gas product; the gas product at the top of the demethanizer is connected to the second main board fin-type heat exchanger through a pipeline, and after being cooled to a certain temperature, it is connected to the reboiler of the helium crude stripping tower through a pipeline to provide heat for the helium crude stripping tower.

[0084] The operating pressure of the demethanizer can be between 1.0 and 6.0 MPaG, which mainly depends on the pressure of the raw natural gas. It should be emphasized that the tower has the ability to remove CO under medium and high pressure operating conditions. 2 The ability to convert CO 2 The natural gas enriched at the bottom of the tower is used to remove CO from the crude helium. 2 The purpose is to determine the pressure according to the different usage scenarios of the cold box.

[0085] After the helium is concentrated twice in the helium crude stripping tower, the purity of the helium is 45%~55%. Although methane is almost removed, it contains more nitrogen impurities, resulting in a low purity of helium. Therefore, the helium mixed gas needs to be cryogenically separated again. Although the second main fin heat exchanger and the third main fin heat exchanger both cool the imported materials to a range of -140°C ~ -180°C, the main purpose of the second main fin heat exchanger is to condense the residual methane component in the mixed gas from the demethanizer, so that the helium crude stripping tower can further separate methane, while the main purpose of the third main fin heat exchanger is to condense the nitrogen component in the mixed gas from the helium crude stripping tower, so that the helium concentration tower can separate most of the nitrogen in the mixed gas and further concentrate the helium.

[0086] The removal of nitrogen in the mixed gas is mainly divided into two stages: the first stage is that after deep cooling in the third main plate fin heat exchanger, the mixture of helium and nitrogen enters the helium concentration tower for primary separation of nitrogen to obtain crude helium and crude nitrogen products; the second stage is that the crude helium enters the helium refining process, and after catalytic dehydrogenation and drying and dehydration, the crude helium enters the PSA purification unit, in which the adsorption tower performs pressure swing adsorption on the nitrogen in the crude helium to separate nitrogen and helium, and obtain high-purity helium and high-purity nitrogen respectively.

[0087] The logistics returned from the reboiler of the helium crude stripping tower to the second main fin heat exchanger is further cooled to -140°C to -180°C and then connected to the inlet channel of the gas-liquid separation tank, where gas-liquid separation is performed. The gas of the gas-liquid separation tank is drawn out from the top pipeline, and the liquid drawn out from the bottom enters from the middle inlet channel of the helium crude stripping tower, where helium is secondary concentrated.

[0088] The liquid drawn from the bottom pipeline of the helium crude stripping tower is connected to the second main fin heat exchanger through a throttle valve and a pipeline, and is connected to the compressor system outside the cold box through a pipeline after recovering cold energy through the pipeline and the second and first main fin heat exchangers in turn, and is compressed to a certain pressure and then returned to the natural gas product pipeline network through a pipeline as part of the pipeline natural gas product. The helium content in the gas at the top of the helium crude stripping tower is about 40% to 50%, and the helium content in the logistics obtained by mixing with the gas-liquid separator tower top gas after being drawn from the top pipeline of the helium crude stripping tower is about 45% to 55%, and is connected to the third main fin heat exchanger through a pipeline, and is connected to the helium concentration tower reboiler through a pipeline after being cooled in the heat exchange channel, so as to provide heat for the helium concentration tower. After the helium returning from the helium concentration tower reboiler to the third main fin heat exchanger continues to cool to -140°C to -180°C, it enters through the middle inlet channel of the helium concentration tower, and further purifies and enriches the helium in the helium concentration tower. The helium content in the crude helium after being concentrated at the top of the helium concentration tower is about 60% to 75%. It is led out through the top pipeline and connected to the third main board fin heat exchanger. After the cold is recovered through the pipeline and the third, second and first main board fin heat exchangers in sequence, it is transported out of the cold box through the pipeline to obtain the crude helium product.

[0089] The liquid led out from the bottom of the helium concentration tower through the pipeline is connected to the third main board fin heat exchanger through a throttle valve, and the cold is recovered through the pipeline and the third, second and first main board fin heat exchangers in turn, and then discharged from the cold box through the pipeline to obtain a crude nitrogen product.

[0090] In summary, the natural gas production high-purity helium device provided by the embodiment of the present invention outputs dry natural gas after drying and dehydrating the raw natural gas through the natural gas drying and dehydration unit, and the crude helium deep cold extraction cold box unit transports the dry natural gas to the first heat exchanger for cooling through the inlet channel set in the purification cold box body, and then purifies and enriches the methane component and concentrates the helium once through the demethanizer, and then cools it in the second heat exchanger and separates the gas and liquid in the gas-liquid separation tank, and the liquid after the gas-liquid separation enters the helium crude extraction tower, and outputs the concentrated helium after the secondary concentration, and then the gas obtained after the gas-liquid separation in the gas-liquid separation tank and the concentrated helium at the top of the helium concentration tower are further purified in the helium concentration tower, and then the catalytic dehydrogenation unit performs dehydrogenation treatment and the drying and dehydration unit performs dehydration treatment, and finally the pressure swing adsorption purification unit removes nitrogen and concentrates and outputs high-concentration helium. Through the device in the present application, helium can be extracted from natural gas containing helium, which has the advantages of high efficiency, high device integration, high purity of helium products, low energy consumption, and continuous large-scale production.

[0091] The above is a detailed introduction to the natural gas high-purity helium production device provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A device for producing high-purity helium from natural gas, characterized in that: include; The natural gas drying and dehydration unit is used to dry and dehydrate the raw natural gas and then output dry natural gas; A crude helium deep cold extraction cold box unit is connected to the natural gas drying and dehydration unit, and comprises a purification cold box body and a first heat exchanger, a second heat exchanger, a third heat exchanger, a demethanizer, a helium crude stripping tower, a helium concentration tower and a gas-liquid separation tank arranged in the purification cold box body. The dry natural gas is transported to the first heat exchanger through an inlet channel arranged in the purification cold box body for cooling, and then enters the demethanizer for methane component purification and enrichment and helium primary concentration, and outputs a first concentrated gas after helium primary concentration. The first concentrated gas is cooled by the second heat exchanger and then subjected to gas-liquid separation in the gas-liquid separation tank. The liquid after gas-liquid separation enters the helium crude stripping tower, and after secondary concentration in the helium crude stripping tower, the concentrated helium is output at the top of the helium crude stripping tower. The gas obtained after the first concentrated gas is subjected to gas-liquid separation in the gas-liquid separation tank and the concentrated helium is further purified in the helium concentration tower, and then a crude helium product is output at the top of the helium concentration tower; A catalytic dehydrogenation unit, used for receiving and performing dehydrogenation treatment on the crude helium product; A drying and dehydration unit, used for dehydrating the crude helium product after the dehydrogenation operation; The pressure swing adsorption purification unit is used to remove nitrogen from the crude helium product after dehydration treatment through an adsorbent filled in an adsorber to concentrate the product and then output helium.

2. The device for producing high-purity helium from natural gas as claimed in claim 1, characterized in that: It also includes a low-temperature adsorption unit and a helium liquefaction unit connected to the output end of the pressure swing adsorption purification unit. The low-temperature adsorption unit is used to produce high-purity helium after low-temperature adsorption operation of the helium produced by the pressure swing adsorption purification unit, and the helium liquefaction unit is used to liquefy the helium produced by the pressure swing adsorption purification unit to produce a high-purity liquid helium product.

3. The device for producing high-purity helium from natural gas as claimed in claim 2, characterized in that: The invention also includes a helium concentration tower condenser arranged in the upper inner cavity of the helium concentration tower, the helium concentration tower condenser is connected to a nitrogen refrigeration system, the nitrogen refrigeration system is used to provide cold capacity for the helium concentration tower condenser for refrigeration, the nitrogen refrigeration system is a liquid nitrogen supply system or a nitrogen circulation system, the nitrogen circulation system includes a nitrogen compressor subsystem and a circulating nitrogen heat exchanger, the nitrogen compressor subsystem, the circulating nitrogen heat exchanger and the helium concentration tower condenser are connected to form a closed cycle, providing cold capacity for the helium concentration tower, the high-pressure nitrogen generated by the nitrogen compressor subsystem is input into the circulating nitrogen heat exchanger for heat exchange cooling, and then provides cold capacity for the helium concentration tower condenser, the low-temperature nitrogen output after heat exchange is returned to the nitrogen compressor subsystem after recovering cold capacity through the circulating nitrogen heat exchanger, so as to form a closed nitrogen cycle.

4. The device for producing high-purity helium from natural gas according to any one of claims 1 to 3, characterized in that: It also includes a cold insulation layer filled in the gaps between the purification cold box body and the first heat exchanger, the second heat exchanger and the third heat exchanger, the demethanizer, the helium crude stripping tower, the helium concentration tower, and the gas-liquid separation tank. The purification cold box body is a steel structure purification cold box body, and the cold insulation layer is an aerogel cold insulation felt, a polyurethane cold insulation layer, a rubber cold insulation layer or a rock wool cold insulation layer.

5. The device for producing high-purity helium from natural gas as claimed in claim 4, characterized in that: It also includes a molecular sieve adsorber arranged in the natural gas drying and dehydration unit, which is used to obtain and output the dry natural gas by adsorbing the easily solidified components in the raw natural gas, and the adsorbent of the molecular sieve adsorber includes at least one of an alumina adsorbent, an activated carbon adsorbent, and a molecular sieve adsorbent.

6. The device for producing high-purity helium from natural gas as claimed in claim 5, characterized in that: It also includes an external compressor system arranged outside the purification cold box body and connected to the first heat exchanger, the second heat exchanger, the third heat exchanger, the demethanizer, and the helium crude stripping tower, which is used to compress the natural gas product obtained in the separation and purification process to a required pressure and discharge it from the purification cold box body through a pipeline to return to the natural gas network as a pipeline natural gas product.

7. The device for producing high-purity helium from natural gas as claimed in claim 6, characterized in that: The reboiler of the demethanizer, the reboiler of the helium crude stripping tower, the reboiler of the helium concentration tower, the condenser of the helium concentration tower, and the heat exchanger of the circulating nitrogen heat exchanger are plate-fin heat exchangers, the reboiler of the demethanizer, the reboiler of the helium crude stripping tower, the reboiler of the helium concentration tower, and the condenser of the helium concentration tower are placed inside the distillation tower, and the demethanizer, the helium crude stripping tower, and the helium concentration tower are structured packing towers, bulk packing towers, or plate towers.

8. The device for producing high-purity helium from natural gas as claimed in claim 7, characterized in that: The first heat exchanger, the second heat exchanger, and the third heat exchanger are plate-fin heat exchangers, shell-and-tube heat exchangers, plate heat exchangers, shell and tube heat exchangers, spiral plate heat exchangers, heat pipe heat exchangers, or jacket heat exchangers, and the first heat exchanger, the second heat exchanger, and the third heat exchanger have multiple heat exchange channels.

9. The device for producing high-purity helium from natural gas as claimed in claim 8, characterized in that: It also includes a temperature display and a parameter setter, wherein the temperature display is used to display the inlet temperature, outlet temperature and air pressure of the first heat exchanger, the second heat exchanger and the third heat exchanger, and the parameter setter is used to set the operating temperature range of the first heat exchanger, the second heat exchanger and the third heat exchanger.

10. The device for producing high-purity helium from natural gas as claimed in claim 9, characterized in that: It also includes an alarm for issuing an alarm message after the actual operating temperature of the first heat exchanger, the second heat exchanger, and the third heat exchanger exceeds a set operating temperature range.

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