Temperature swing adsorption helium low-temperature purification system

Abstract

The invention discloses a temperature swing adsorption helium low-temperature purification system which comprises a vacuum cold box, and a first-stage dividing wall heat exchanger, a liquid cold medium Dewar, a high-temperature area adsorption unit, a second-stage dividing wall heat exchanger, a cold head heat exchanger and a low-temperature area adsorption unit are sequentially connected in the vacuum cold box in the gas transmission direction. Wherein the input end of the first-stage dividing wall heat exchanger is connected with the outside through a pipeline, and is used for introducing crude helium; the high-temperature area adsorption unit is used for adsorbing impurity gas with the boiling point temperature being greater than or equal to 77K in the crude helium, and the low-temperature area adsorption unit is used for adsorbing impurity gas with the boiling point temperature being 20K-30K in the crude helium, so that high-purity helium is obtained. According to the invention, not only can high-flow high-component impurity gas with the boiling point of 77K or above be treated, but also high-flow high-component impurity gas with the boiling point of 30K or below can be treated, and high-flow multi-component high-concentration industrial production working conditions can be better matched by adopting physical adsorption of the high-temperature and low-temperature region adsorbents.

Description

Technical Field

[0001] The invention relates to a deep low temperature separation and purification technology for rare gases by adsorption, and in particular to a temperature-variable adsorption helium low temperature purification system. Background Art

[0002] High-purity helium plays a vital role in high-tech fields such as superconducting technology, magnetic resonance imaging (MRI), chip manufacturing, and aerospace due to its unique physical and chemical properties. China's dependence on foreign helium is extremely high, with imports accounting for 85% for a long time. Therefore, the urgency of developing domestic large-scale low-temperature helium extraction processes is no less than that of fields such as chips. Therefore, helium energy reserves are of great significance to the development of science and technology.

[0003] At present, helium extraction from flash gas of liquefied natural gas (BOG helium extraction for short) has a more efficient preparation capacity. This process route not only reduces production costs, but also can realize the recycling of energy and reduce energy consumption.

[0004] BOG helium extraction mainly utilizes cryogenic distillation and palladium membrane separation in the previous stage to remove trace impurities such as CH4 and H2 on the one hand, and continuously enrich helium on the other hand, resulting in a high proportion of helium in the raw gas before entering the helium purification device.

[0005] The impurity components of the crude helium entering the helium purification device are mainly: NE, N2, O2, Ar, CO2, CH4, etc.

[0006] The technology of soaking the adsorbent cylinder with liquid cold medium in the high-temperature zone is relatively mature. The temperature of the adsorbent is reduced to the temperature in the high-temperature zone, and trace amounts of N2, CH4, CO2, CO, O2, and Ar in the crude helium can be removed by physical adsorption.

[0007] However, the traditional high temperature zone low temperature adsorption method can only remove impurity gases with a boiling point greater than or equal to the boiling point of nitrogen. Due to the low boiling points of neon and hydrogen, and the similar physical and chemical properties of neon and helium, the adsorption capacity of the adsorbent in this temperature zone for neon and hydrogen is very limited. Therefore, it is very difficult to remove impurity gases and obtain high-purity helium by adsorption in the high temperature zone.

[0008] Due to the difference in boiling points between neon and helium, the main processes for removing neon from helium are: deep cryogenic freezing below the solidification point of neon, low temperature distillation in the temperature zone of neon liquefaction point, and low temperature adsorption. However, the deep cryogenic freezing at the solidification point of neon is not suitable for production conditions with large processing volume and large components of neon; since the boiling points of neon and helium are not much different, the low temperature distillation in the temperature zone of neon liquefaction point actually requires more stringent tower plate and tower body design, and extremely strict temperature control requirements, which may require repeated operations, increasing production costs; therefore, it is more likely to use low temperature adsorption to design the process for industrial helium extraction equipment with large processing volume and high components of neon.

[0009] Most of the related technologies involved in the existing helium cryogenic adsorption purification system are 77K liquid nitrogen immersion type two-tower or three-tower switching helium purification process designs. There is no complete new generation helium cryogenic adsorption purification process flow that can handle both large-flow high-component impurity gases with boiling points above 77K (CH4, N2, CO, CO2, O2+Ar) and large-flow high-component impurity gases with boiling points below 30K (Ne, H2). Summary of the invention

[0010] Purpose of the invention: The purpose of the present invention is to provide a temperature-swing adsorption helium low-temperature purification system, which can not only process large-flow, high-component impurity gases with boiling points above 77K (CH4, N2, CO, CO2, O2+Ar), but also process large-flow, high-component impurity gases with boiling points below 30K (Ne, H2). The use of physical adsorption of adsorbents in high and low temperature zones can better match the industrial production conditions of large-flow, multi-component and high-concentration.

[0011] Technical solution: A temperature-swing adsorption helium low-temperature purification system of the present invention comprises a vacuum cold box, wherein the vacuum cold box is provided with a purification system, wherein the purification system comprises a primary partition wall heat exchanger, a liquid cold medium dewar, a high-temperature zone adsorption unit, a secondary partition wall heat exchanger, a cold head heat exchanger and a low-temperature zone adsorption unit which are sequentially connected in the vacuum cold box according to the gas transmission direction; wherein the input end of the primary partition wall heat exchanger is connected to the outside through a pipeline for introducing crude helium;

[0012] The high temperature zone adsorption unit is used to adsorb impurity gases with a boiling point temperature ≥ 77K in the crude helium, and the low temperature zone adsorption unit is used to adsorb impurity gases with a boiling point temperature in the temperature range of 20K-30K in the crude helium, thereby obtaining high-purity helium.

[0013] The purification system also includes a compressor, the main air outlet pipeline of the compressor is connected to the vacuum cold box through two air outlet bypasses, and the air inlet of the compressor is connected to the vacuum cold box through a return air pipeline.

[0014] Furthermore, the purification system adopts a double-tower design, and the two purification systems have the same structure, and one purification system is purifying while the other purification system is regenerating.

[0015] Furthermore, when the purification system is in the purification stage, the compressor therein provides circulating compressed helium to a refrigerator connected to a cold head heat exchanger in the purification system, so that the refrigerator can generate a cold source by doing work.

[0016] Furthermore, when the purification system is in the regeneration stage, one outlet bypass of the compressor in the purification system in the regeneration stage is used to provide the high-temperature zone adsorption unit and the low-temperature zone adsorption unit in the purification system with normal temperature, high pressure and high purity gas required for hot blowing, and the other outlet bypass is used to provide the high-temperature zone adsorption unit and the low-temperature zone adsorption unit in the purification system with normal temperature, high pressure and high purity gas required for cold blowing; wherein, during the cold blowing process, the normal temperature, high pressure and high purity gas needs to first be pre-cooled to the liquid cold medium temperature by a liquid cold medium Dewar.

[0017] Furthermore, during the cold blowing process, the room temperature, high pressure and high purity gas coming out from another outlet bypass of the compressor is pre-cooled by the liquid cold medium Dewar, and after the temperature drops to the temperature of the liquid cold medium, the high temperature zone adsorption unit and the low temperature zone adsorption unit are cold-blown simultaneously until the high temperature zone adsorption unit and the low temperature zone adsorption unit are both cooled to the temperature of the liquid cold medium.

[0018] Furthermore, after the low temperature zone adsorption unit is cooled to the temperature of the liquid cold medium, the low temperature zone adsorption unit is cooled to the low temperature zone of 20K-30K by using a cold plate direct cooling adsorber or a pressure equalizing bypass valve partition cold blowing cooling method.

[0019] Furthermore, the pressure equalizing bypass valve partition wall cold blowing cooling method is to reduce the temperature of the high-purity helium obtained in the purification stage to the low-temperature zone through the bypass pipeline valve under the action of the cold head heat exchanger, and use the high-purity helium whose temperature has been reduced to the low-temperature zone to circulate and blow the adsorption unit in the low-temperature zone until the temperature of the adsorption unit in the low-temperature zone is cooled to the low-temperature zone of 20K-30K.

[0020] Furthermore, the liquid cold medium Dewar is used to reduce the temperature of the crude helium to a high temperature zone of 77K-150K, and the cold head heat exchanger is used to reduce the temperature of the neon-helium-hydrogen to a low temperature zone of 20K-30K.

[0021] Furthermore, the high temperature zone adsorption unit and the low temperature zone adsorption unit both use a low temperature pressure vessel, the interior of the low temperature pressure vessel is filled with an adsorbent, and the surface of the adsorbent has a highly porous structure.

[0022] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows:

[0023] The present invention effectively integrates two adsorption temperature zones, a high temperature zone and a low temperature zone, into one vacuum cold box. Crude helium gas with a high helium content undergoes two-stage physical adsorption by a first high temperature zone adsorption unit and a first low temperature zone adsorption unit, thereby removing most of the impurity gases (the first high temperature zone adsorption unit adsorbs and removes methane, nitrogen, carbon monoxide, carbon dioxide and oxygen-argon impurity gases, and the first low temperature zone adsorption unit adsorbs and removes neon and hydrogen), and finally obtains ultra-high purity helium gas. The integrated combination design of the high temperature zone adsorption unit and the low temperature zone adsorption unit can effectively solve the treatment requirements of multi-component high-concentration impurities.

[0024] A "double-tower" design is introduced in both the high-temperature zone adsorption unit and the low-temperature zone adsorption unit. Under the control of valves, two sets of parallel adsorbers can purify in one "tower" while the other "tower" starts to regenerate, thus achieving uninterrupted operation and greatly improving the raw gas processing capacity and processing efficiency. In addition, compared with the single adsorber operation unit in the prior art, it can effectively extend the service life of the adsorber.

[0025] The high-temperature zone adsorption unit and the low-temperature zone adsorption unit are cold-blown by utilizing the normal-temperature, high-pressure, high-purity gas in the closed-loop circulation pipeline of the compressor combined with the liquid cold medium Dewar pre-cooling. The high-temperature zone adsorption unit eliminates the method of immersion cooling using liquid cold medium, thereby effectively reducing the system's liquid nitrogen consumption and thereby reducing equipment costs.

[0026] The low temperature zone adsorption unit has a large adsorption capacity for neon and can effectively achieve the removal of high concentration neon impurities with a small adsorbent filling amount.

[0027] The low temperature zone adsorption unit can better match the production conditions of large flow and high component neon.

[0028] During the regeneration process, the hot blowing uses the normal temperature, high pressure and high purity gas in the closed cycle of the compressor bypass to purge and reheat, which effectively reduces the external energy consumption, eliminates the use of external heating equipment and circulation equipment, and reduces the equipment manufacturing cost.

[0029] The "one machine, two functions" flow path design of the compressor effectively simplifies the process flow and realizes different functions at different stages.

[0030] This invention example effectively integrates the low-temperature adsorption design of high and low temperature zones into one cold box, making the entire equipment more integrated and the standardized manufacturing cost more economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic structural diagram of a temperature-swing adsorption helium low-temperature purification system disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings of the specification.

[0033] like Figure 1As shown, the temperature-swing adsorption helium low-temperature purification system of the present invention involves the following components: a vacuum cold box 1, a first low-temperature zone adsorption unit 21, a second low-temperature zone adsorption unit 22, a first cold head heat exchanger 31, a second cold head heat exchanger 32, a first and second-stage partition wall heat exchanger 41, a second and second-stage partition wall heat exchanger 42, a first high-temperature zone adsorption unit 51, a second high-temperature zone adsorption unit 52, a liquid cold medium dewar 6, a first and first-stage partition wall heat exchanger 71, a second and first-stage partition wall heat exchanger 72, a first compressor 81, a second compressor 82, a first vaporizer 91, a second vaporizer 92, a third vaporizer 93, a fourth vaporizer 94, a first pipeline automatic control valve 10, a second pipeline automatic control valve 111, and a third pipeline automatic control valve 12. Automatic control valve 112, fourth pipeline automatic control valve 113, fifth pipeline automatic control valve 114, sixth pipeline automatic control valve 115, seventh pipeline automatic control valve 116, eighth pipeline automatic control valve 117, ninth pipeline automatic control valve 118, tenth pipeline automatic control valve 119, eleventh pipeline automatic control valve 120, twelfth pipeline automatic control valve 121, thirteenth pipeline automatic control valve 122, fourteenth pipeline automatic control valve 14, fifteenth pipeline automatic control valve 15, sixteenth pipeline automatic control valve 16, vacuum pump 17, first pressure relief pipeline 23, second pressure relief pipeline 25, third pressure relief pipeline 24, fourth pressure relief pipeline 26.

[0034] The first primary interlayer heat exchanger 71, the liquid cold medium dewar 6, the first high temperature zone adsorption unit 51, the first secondary interlayer heat exchanger 41, the first cold head heat exchanger 31 and the first low temperature zone adsorption unit 21 are connected in sequence in the vacuum cold box 1 according to the gas transmission direction; wherein, the input end of the first primary interlayer heat exchanger 71 is connected to the outside through a pipeline for introducing crude helium. Crude helium is a multi-component raw gas with a high helium content. A second pipeline automatic control valve 111 is arranged on the pipeline at the input end of the first primary interlayer heat exchanger 71. The main outlet pipeline of the first compressor 81 is connected to the vacuum cold box 1 through two outlet bypasses, and the air inlet of the first compressor 81 is connected to the vacuum cold box 1 through a return air pipeline; the above constitutes a purification system. The first compressor 81 is used to provide a cold source for the first cold head heat exchanger 31 during the purification stage.

[0035] In this embodiment, the first high temperature zone adsorption unit 51 and the first low temperature zone adsorption unit 21 both adopt a low temperature pressure vessel, and the interior of the low temperature pressure vessel is filled with an adsorbent. The adsorbent is a highly porous structure with many tiny pores on its surface, which can provide a larger adsorption surface area, thereby increasing the adsorption performance.

[0036] After the second pipeline automatic control valve 111 is opened, the crude helium gas sequentially enters the first primary interlayer heat exchanger 71, the liquid cold medium Dewar 6, the first high temperature zone adsorption unit 51, the first secondary interlayer heat exchanger 41, the first cold head heat exchanger 31 and the first low temperature zone adsorption unit 21.

[0037] The liquid cold medium Dewar 6 reduces the temperature of the crude helium to the high temperature zone of 77K-150K, and the cold head heat exchanger 31 reduces the temperature of the neon, helium and hydrogen to the low temperature zone of 20K-30K. The first high temperature zone adsorption unit 51 adsorbs impurity gases with a boiling point temperature ≥77K in the crude helium, and the first low temperature zone adsorption unit 21 adsorbs impurity gases with a boiling point temperature in the temperature zone of 20K-30K in the crude helium, thereby obtaining high-purity helium. The cold source of the first high temperature zone adsorption unit 51 comes from the liquid cold medium Dewar 6 with the same temperature in the high temperature zone. The first low temperature zone adsorption unit 21 mainly performs physical adsorption and removal of neon and hydrogen in helium, and the required stable cold source in the low temperature zone comes from the cold head heat exchanger 31. The cold head heat exchanger 31 uses the refrigerator connected to it to provide a stable cold source, and the refrigerator needs to be equipped with a first compressor 81 for driving.

[0038] The high temperature zone adsorption unit and the low temperature zone adsorption unit are integrated in one process. The impurity gas (CH4, N2, CO, CO2, O2+Ar) with a boiling point temperature ≥77K in the crude helium is first removed by the first high temperature zone adsorption unit 51, and then the impurity gas (Ne, H2) with a boiling point temperature ≥20K in the crude helium is removed by the first low temperature zone adsorption unit 21, thereby achieving the effect of purifying the helium. Among them, the maximum Ne concentration that can be processed by the first low temperature zone adsorption unit 21 can reach 10%. The entire temperature swing adsorption process occurs in the vacuum cold box 1.

[0039] The second primary partition heat exchanger 72, the liquid cold medium dewar 6, the second high temperature zone adsorption unit 52, the second secondary partition heat exchanger 42, the second cold head heat exchanger 32 and the second low temperature zone adsorption unit 22 are sequentially connected in the vacuum cold box 1 according to the gas transmission direction; wherein, the input end of the second primary partition heat exchanger 72 is connected to the outside through a pipeline, and the second primary partition heat exchanger 72 can also be fed with crude helium. A third pipeline automatic control valve 112 is arranged on the pipeline at the input end of the second primary partition heat exchanger 72. The main outlet pipeline of the second compressor 82 is connected to the vacuum cold box 1 through two outlet bypasses, and the air inlet of the second compressor 82 is connected to the vacuum cold box 1 through a return air pipeline. The above constitutes another purification system.

[0040] In the present invention, the purification system adopts a "double tower" design, that is, there are two purification systems with the same structure, one of which is purifying while the other is regenerating. The working and regeneration states are controlled by an external valve to achieve uninterrupted continuous operation of the device, and convenient switching and regeneration after adsorption saturation. This method not only improves the processing capacity and processing efficiency of the raw gas, but also allows the device to maintain continuous operation.

[0041] In the present invention, the first compressor 81 and the second compressor 82 have two working conditions. One working condition is the purification stage, and its main function is to provide circulating compressed helium to the refrigerator connected to the cold head heat exchanger for the refrigerator to work and generate a cold source; the other working condition is the regeneration stage, and the main outlet pipe of the compressor is connected to the vacuum cold box 1 through two outlet bypasses, and the air inlet of the compressor is connected to the vacuum cold box 1 through a return air pipe. The two outlet bypasses and one return air pipe form a closed pipeline in the vacuum cold box 1, which is mainly used for hot blowing and cold blowing in the regeneration stage of the adsorber in the high and low temperature zones. The two flow paths of hot blowing and cold blowing are two independent closed cycle pipelines, sharing a return air pipe. The details are as follows:

[0042] The outlet bypass where the fourth pipeline automatic control valve 113 is located and the outlet bypass where the seventh pipeline automatic control valve 116 is located are hot blowing pipelines. During hot blowing, the fourth pipeline automatic control valve 113 (or the seventh pipeline automatic control valve 116) is opened, and the internal flow path of the vacuum cold box 1 is: the normal temperature gas at the outlet of the first compressor 81 (or the second compressor 82) is blown directly to the first high temperature zone adsorption unit 51 and the second low temperature zone adsorption unit 22 (or the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22) along the outlet bypass where the fourth pipeline automatic control valve 113 is located (or the outlet bypass where the seventh pipeline automatic control valve 116 is located); then, it exits the vacuum cold box 1 along the return air pipeline of the first compressor 81 (or the second compressor 82) and enters the air inlet of the first compressor 81 (or the second compressor 82), forming a closed gas cycle.

[0043] The gas outlet bypass where the fifth pipeline automatic control valve 114 is located and the gas outlet bypass where the sixth pipeline automatic control valve 115 is located are cold blowing pipelines. During cold blowing, the fifth pipeline automatic control valve 114 (or the sixth pipeline automatic control valve 115) is opened, and the internal flow path of the vacuum cold box 1 is: the normal temperature gas at the outlet of the first compressor 81 (or the second compressor 82) passes through a partition heat exchanger and a liquid cold medium Dewar along the outlet bypass where the fifth pipeline automatic control valve 114 is located (or the outlet bypass pipeline where the sixth pipeline automatic control valve 115 is located), and is pre-cooled to the temperature of the high temperature zone and then directly blown to the first high temperature zone adsorption unit 51 and the second low temperature zone adsorption unit 22 (or the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22); then, it is reheated along the return air pipeline of the first compressor 81 (or the second compressor 82) and exits the vacuum cold box 1, and enters the air inlet of the first compressor 81 (or the second compressor 82); this cold blowing step is a cooling process in the high temperature zone, and the other 20-30K temperature zone is completed from the main air inlet.

[0044] As mentioned above, in the multi-component raw gas, except for helium, nitrogen and neon account for a relatively large proportion, and the rest are trace methane, carbon dioxide and other gas impurities; nitrogen and trace methane and carbon dioxide are adsorbed and removed in the adsorption unit of the front-stage high-temperature zone; neon and trace hydrogen with a high component proportion cannot be completely removed by low-temperature separation in the front-stage high-temperature zone, wherein the physical and chemical properties of neon are very similar to those of helium, such as: small molecular diameter, difficult to adsorb, low boiling point, etc. Therefore, an embodiment of the present invention provides a low-temperature adsorption helium purification method for removing multi-component high-concentration impurities in the front-stage high-temperature zone + the rear-stage low-temperature zone.

[0045] The present invention adopts a high temperature zone adsorption unit to better match the industrial production conditions of large flow and multi-component impurities. In addition, the integrated design of the system can not only reduce the equipment production cost, but also avoid the energy consumption of liquid cooling medium.

[0046] The working process of the temperature-swing adsorption helium low-temperature purification system of the present invention is described below by taking the purification in the left tower and the regeneration in the right tower as an example.

[0047] S1, during normal purification operation, the crude helium enters the vacuum cold box 1 through the second pipeline automatic control valve 111, and firstly passes through the first primary partition wall heat exchanger 71 for primary cooling; then, it enters the liquid cold medium dewar 6 for precooling, and the temperature drops to the high temperature zone temperature and exits the liquid cold medium dewar 6, and then the crude helium enters the first high temperature zone adsorption unit 51 to remove nitrogen, methane, carbon dioxide, trace hydrogen and neon. The adsorbent in the first high temperature zone adsorption unit 51 completes the physical adsorption of the impurity gas, that is, methane and nitrogen can be removed, and neon, helium and hydrogen are obtained at the outlet.

[0048] S2. The high-purity neon, helium and hydrogen coming out of the first high-temperature zone adsorption unit 51 in step S1 is first cooled through the first and second-stage inter-wall heat exchangers 41 to further reduce the temperature; then the temperature of this part of the gas is further reduced to the low-temperature zone temperature by using a refrigerator, and the first cold head heat exchanger 31 is used to realize this cooling process. The neon, helium and hydrogen coming out of the first cold head heat exchanger 31 enter the first low-temperature zone adsorption unit 21. The first low-temperature zone adsorption unit 21 is also a low-temperature pressure vessel, which is filled with an adsorbent. The adsorbent is a highly porous structure with many tiny pores on its surface, which can provide a larger adsorption surface area, thereby increasing the adsorption performance. As the temperature decreases, the adsorption depth of the adsorbent is better. In other words, its adsorption capacity for non-condensable neon is greater. Therefore, the process of removing neon from helium can be completed by a small amount of adsorbent, and high-purity helium can be obtained at the outlet of the first low-temperature zone adsorption unit 21.

[0049] The outlet of the first low temperature zone adsorption unit 21 obtains high purity helium, which is restored to room temperature through the first and second stage heat exchangers 41 and the first and first stage heat exchangers 71 and then leaves the vacuum cold box 1. The room temperature high purity helium leaves the system through the twelfth pipeline automatic control valve 121.

[0050] S3. While the left tower is purifying, the right tower begins to regenerate.

[0051] S4, pressure relief: the right tower regeneration opens the tenth pipeline automatic control valve 119, the eleventh pipeline automatic control valve 120, and the sixteenth pipeline automatic control valve 16; the high-temperature gas in the second high-temperature zone adsorption unit 52 enters the fourth vaporizer 94 through the third pressure relief pipeline 24 in sequence, resets to normal temperature in the fourth vaporizer 94, and passes through the sixteenth pipeline automatic control valve 16 to the pressure relief recovery path, thereby completing the pressure relief of the second high-temperature zone adsorption unit 52;

[0052] The low-temperature gas in the second low-temperature zone adsorption unit 22 enters the third vaporizer 93 through the fourth pressure relief pipeline 26 in turn, resets to room temperature in the third vaporizer 93, and goes to the pressure relief recovery path through the sixteenth pipeline automatic control valve 16, thus completing the pressure relief of the second low-temperature zone adsorption unit 22; the second high-temperature zone adsorption unit 52 and the second low-temperature zone adsorption unit 22 are simultaneously pressure-relieved until the pressure of the second high-temperature zone adsorption unit 52 and the second low-temperature zone adsorption unit 22 drops to normal pressure, the pressure relief ends, and the sixteenth pipeline automatic control valve 16 is closed. The pressure relief gas is mainly crude helium gas, which has a high helium content and has a great recycling significance.

[0053] S5, hot blowing: open the seventh pipeline automatic control valve 116 and the fifteenth pipeline automatic control valve 15; the normal temperature, high pressure and high purity gas in the pipeline where the seventh pipeline automatic control valve 116 is located passes through the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 in turn to realize the hot blowing process of the high and low temperature zone adsorption units.

[0054] It is worth noting that the normal temperature and high pressure gas in the pipeline where the seventh pipeline automatic control valve 116 is located is a normal temperature and high pressure high purity gas that has a closed cycle inside the compressor. The closed cycle does not participate in any flow path of the main system, so the gas volume, pressure, and purity of this part of the gas will not be affected. And the closed cycle normal temperature and high pressure high purity gas includes but is not limited to helium.

[0055] During the hot blowing process, the desorbed gas released by the second high temperature zone adsorption unit 52 passes through the third pressure relief pipeline 24, enters the fourth vaporizer 94, resets to normal temperature, and passes through the fifteenth pipeline automatic control valve 15 to the pressure relief and emptying path;

[0056] During the hot blowing process, the desorbed gas released by the second low temperature zone adsorption unit 22 passes through the fourth pressure relief pipeline 26, enters the third vaporizer 93, resets to room temperature, passes through the fifteenth pipeline automatic control valve 15, and goes to the pressure relief and emptying path; at this time, the refrigerator is in the shutdown state. After the hot blowing is completed, the fifteenth pipeline automatic control valve 15 is closed.

[0057] In this embodiment, the second compressor 82 utilizes the normal temperature, high pressure and high purity gas in the compressor bypass hot blowing pipeline to heat blow the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 .

[0058] In the present invention, the second compressor 82 utilizes the normal temperature, high pressure and high purity gas in the compressor bypass hot blowing pipeline to simultaneously hot blow the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22, replacing the conventional process of hot blowing using a heater and a circulating fan, thereby reducing the consumption of the medium and the consumption of external equipment and energy.

[0059] The hot blowing process first requires desorption of the adsorbent in the second high temperature zone adsorption unit 52 and the adsorbent in the second low temperature zone adsorption unit 22. This step requires the second compressor 82 to use normal temperature and high pressure helium for reheating treatment. The flow sequence is to first blow the second high temperature zone adsorption unit 52, and then pass through the second low temperature zone adsorption unit 22 and return to the compressor return port.

[0060] S6, replacement: After the hot blow pressure relief is completed, the replacement work of the adsorption unit begins. This process mainly involves evacuation and filling of the system with high-purity helium.

[0061] Evacuate: Open the fourteenth pipeline automatic control valve 14 and the vacuum pump 17, and use the vacuum pump 17 to evacuate the second high-temperature zone adsorption unit 52 and the second low-temperature zone adsorption unit 22;

[0062] The gas evacuated from the second high temperature zone adsorption unit 52 goes to the adsorption unit evacuation path through the third pressure relief pipeline 24, the fourth vaporizer 94, the fourteenth pipeline automatic control valve 14, and the vacuum pump 17;

[0063] The gas evacuated from the second low temperature zone adsorption unit 22 goes to the adsorption unit evacuation path through the fourth pressure relief pipeline 26, the third vaporizer 93, the fourteenth pipeline automatic control valve 14, and the vacuum pump 17;

[0064] High-purity helium filling of the system: After the evacuation is completed, the fourteenth pipeline automatic control valve 14 and the vacuum pump 17 are closed, and the first pipeline automatic control valve 10 is opened. The high-purity helium at the outlet of the first-stage partition wall heat exchanger 71 in the left tower enters the right tower through the pipeline where the fourteenth pipeline automatic control valve 14 is located, so as to realize the filling of the right tower;

[0065] The above is one evacuation and one inflation. The entire replacement process requires three evacuations and three inflations.

[0066] S7, cold blowing: The system cooling stage is divided into two stages, the first stage: in order to achieve the simultaneous cooling of the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22, the normal temperature, high pressure, high purity gas in the gas outlet bypass where the sixth pipeline automatic control valve 115 is located is used for cooling. The sixth pipeline automatic control valve 115 is opened, and the normal temperature, high pressure, high purity gas in the gas outlet bypass where the sixth pipeline automatic control valve 115 is located first uses the liquid cold medium in the liquid cold medium dewar 6 as a cold source, and then passes through the liquid cold medium dewar 6 outside the liquid cold medium dewar 6 to cool to the high temperature zone temperature, and then starts to cold blow the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 in turn, and cold blows the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 to the high temperature zone.

[0067] It is worth noting that the normal temperature, high pressure, high purity gas in the pipeline where the sixth pipeline automatic control valve 115 is located is a normal temperature, high pressure, high purity gas that has a closed cycle inside the compressor. The closed cycle does not participate in any flow path of the main system, so the gas volume, pressure, and purity of this part of the gas will not be affected. The closed cycle normal temperature, high pressure, high purity gas includes but is not limited to helium.

[0068] In this embodiment, the normal temperature, high pressure and high purity gas in the gas outlet bypass pipeline where the sixth pipeline automatic control valve 115 is located is pre-cooled by the liquid cold medium Dewar 6. After the temperature drops to the temperature of the liquid cold medium, the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 are cold-blown at the same time until the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 are simultaneously cooled to the high temperature zone of the liquid cold medium.

[0069] The cold blowing method using the closed-cycle helium of the second compressor 82 combined with the pre-cooling of the liquid cold medium Dewar 6 replaces the traditional liquid cold medium immersion method, thus greatly reducing the consumption of the cold medium.

[0070] The second stage: After the second high temperature zone adsorption unit 52 and the second low temperature zone adsorption unit 22 are cold-blown to the high temperature zone, the second low temperature zone adsorption unit 22 needs to be cold-blown to the 20-30K temperature zone. There are two ways to continue to cold-blown the second low temperature zone adsorption unit 22 to the 20-30K temperature zone: the second low temperature zone adsorption unit 22 is cooled to the 20K-30K low temperature zone by using the equalizing pressure bypass valve inter-wall cold-blowing cooling method or the cold plate direct cooling adsorber method. The details are as follows:

[0071] Among them, the pressure equalizing bypass valve inter-wall cold blowing cooling method is: through the first pipeline automatic control valve 10, the high-purity helium gas that has finished purification in the left tower is cooled to the low-temperature zone temperature through the bypass pipeline valve under the action of the second cold head heat exchanger 32, and then circulated to blow the second low-temperature zone adsorption unit 22 until the temperature of the second low-temperature zone adsorption unit 22 drops to the low-temperature zone temperature (20K-30K), which is considered to be the end of this stage, and it is kept in the cold standby state thereafter, and the bypass valve of the high-purity helium to the right tower is continuously opened until the next tower cutting.

[0072] The method of direct cooling the adsorber by the cold plate is as follows: after the cold head of the refrigerator is turned on, the copper cold plate is directly in contact with the stainless steel cylinder of the adsorption unit to conduct cooling to complete the separate cooling of the second low temperature zone adsorption unit 22. This method has a relatively long cooling time.

[0073] The above two methods for continuing to cold blow the second low-temperature zone adsorption unit 22 to the 20-30K temperature zone both use a refrigerator as a cold source. One method is to cool the low-temperature zone adsorption unit through a cold plate in contact with the cold head of the refrigerator; the other method is to use a partition heat exchanger in contact with the cold head of the refrigerator. The second method requires the participation of the main air inlet path of the system, which is equivalent to two towers working at the same time.

[0074] After the above four steps are completed, the tower can be considered to be fully regenerated and ready to be cut off for purification process.

[0075] The present invention adopts a "double-tower" switching helium purification system, which can effectively improve industrial production efficiency and reduce production costs. The closed circulation gas of an external compressor (the first compressor 81 and the second compressor 82) is used to achieve the function of rapid regeneration.

[0076] The integrated system design of the embodiment of the present invention is highly operable, the heat exchanger involved is relatively simple, and the design pressure of the entire system is relatively low, so the manufacturing difficulty is not great. The integrated system design can reduce the equipment production cost and avoid the energy consumption of liquid cooling medium in the process of realizing industrial production.

[0077] The system of the present invention is of integral design, and the switching of the two towers is arranged in the same vacuum cold box, and logic control is performed through external valves to keep the equipment running continuously.

[0078] In addition, the embodiment of the present invention uses a refrigerator as a cold source and a liquid cold medium to assist in pre-cooling and heat exchange. Compared with the low-temperature distillation separation and low-temperature freezing separation methods in the prior art, the low-temperature adsorption method as the core of the entire system is more innovative and more suitable for the separation and removal of large-flow, multi-component, and high-concentration impurities in industry.

[0079] The refrigerator used in the embodiment of the present invention has a stable cooling capacity output, which can ensure the smooth operation of the entire system.

[0080] The compressor achieves the role of "one machine with two uses". During the normal purification process, it provides high-pressure circulating helium to the refrigerator in a closed manner. During the adsorber regeneration process, the refrigerator cold head stops working, and the compressor helium bypass provides circulating helium for regeneration in a closed manner.

[0081] The embodiment of the present invention can prolong the service life of the equipment through the regeneration method, and can effectively recover the separated impurity gas. This method ensures the high-purity refining of helium while improving the processing volume and processing efficiency of raw gas.

[0082] The temperature-swing adsorption helium low-temperature purification system provided in the embodiment of the present invention is a temperature-swing adsorption system integrating adsorption of adsorbents in high-temperature zones and adsorption of adsorbents in low-temperature zones. It is suitable for purification requirements with higher helium purity. Through logical control, continuous operation of the equipment can be achieved, which is more suitable for large-scale industrial production.

Claims

1. A temperature swing adsorption helium low temperature purification system, characterized in that: The invention comprises a vacuum cold box (1), wherein the vacuum cold box (1) is provided with a purification system, wherein the purification system comprises a primary partition wall heat exchanger, a liquid cold medium dewar (6), a high temperature zone adsorption unit, a secondary partition wall heat exchanger, a cold head heat exchanger and a low temperature zone adsorption unit which are sequentially connected in the vacuum cold box (1) according to the gas transmission direction; wherein the input end of the primary partition wall heat exchanger is connected to the outside through a pipeline for introducing crude helium; The high temperature zone adsorption unit is used to adsorb impurity gases with a boiling point temperature ≥ 77K in the crude helium, and the low temperature zone adsorption unit is used to adsorb impurity gases with a boiling point temperature in the temperature range of 20K-30K in the crude helium, thereby obtaining high-purity helium.

2. The temperature swing adsorption helium low temperature purification system according to claim 1, characterized in that: The purification system also includes a compressor, the main air outlet pipeline of the compressor is connected to the vacuum cold box (1) through two air outlet bypasses, and the air inlet of the compressor is connected to the vacuum cold box (1) through a return air pipeline.

3. The temperature swing adsorption helium low temperature purification system according to claim 2, characterized in that: The purification system adopts a double-tower design, and the two purification systems have the same structure. While one purification system is working, the other purification system is regenerated.

4. The temperature swing adsorption helium low temperature purification system according to claim 3, characterized in that: When the purification system is in the purification stage, the compressor therein provides circulating compressed helium to the refrigerator connected to the cold head heat exchanger in the purification system, so that the refrigerator can generate a cold source by doing work.

5. The temperature swing adsorption helium low temperature purification system according to claim 3, characterized in that: When the purification system is in the regeneration stage, one outlet bypass of the compressor in the purification system in the regeneration stage is used to provide the high-temperature zone adsorption unit and the low-temperature zone adsorption unit in the purification system with normal temperature, high pressure and high purity gas required for hot blowing, and the other outlet bypass is used to provide the high-temperature zone adsorption unit and the low-temperature zone adsorption unit in the purification system with normal temperature, high pressure and high purity gas required for cold blowing; In the cold blowing process, the room temperature, high pressure and high purity gas needs to be pre-cooled to the liquid cooling medium temperature by passing through the liquid cooling medium dewar (6).

6. The temperature swing adsorption helium low temperature purification system according to claim 5, characterized in that: During the cold blowing process, the room temperature, high pressure and high purity gas coming out from another outlet bypass of the compressor is precooled by the liquid cold medium dewar (6). After the temperature drops to the temperature of the liquid cold medium, the high temperature zone adsorption unit and the low temperature zone adsorption unit are cold blown at the same time until the high temperature zone adsorption unit and the low temperature zone adsorption unit are both cooled to the temperature of the liquid cold medium.

7. The temperature swing adsorption helium low temperature purification system according to claim 6, characterized in that: After the low temperature zone adsorption unit is cooled to the temperature of the liquid cold medium, the low temperature zone adsorption unit is cooled to the low temperature zone of 20K-30K by using a cold plate direct cooling adsorber method or a pressure equalizing bypass valve partition cold blowing cooling method.

8. The temperature swing adsorption helium low temperature purification system according to claim 7, characterized in that: The pressure equalizing bypass valve partition wall cold blowing cooling method is to cool the high-purity helium obtained in the purification stage to a low-temperature zone through a bypass pipe valve under the action of a cold head heat exchanger, and use the high-purity helium whose temperature has been reduced to the low-temperature zone to circulate and blow the adsorption unit in the low-temperature zone until the temperature of the adsorption unit in the low-temperature zone is cooled to a low-temperature zone of 20K-30K.

9. The temperature swing adsorption helium low temperature purification system according to claim 1, characterized in that: The liquid cold medium Dewar (6) is used to reduce the temperature of the crude helium gas to a high temperature range of 77K-150K, and the cold head heat exchanger is used to reduce the temperature of the neon, helium and hydrogen gas to a low temperature range of 20K-30K.

10. The temperature swing adsorption helium low temperature purification system according to claim 1, characterized in that: The high temperature zone adsorption unit and the low temperature zone adsorption unit both adopt a low temperature pressure vessel, the interior of the low temperature pressure vessel is filled with an adsorbent, and the surface of the adsorbent has a highly porous structure.

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