TWI885888B - Helium gas purification device and method for purifying helium gas - Google Patents

Abstract

A helium gas purification device, including: an inlet for receiving helium gas raw materials; a first cooling unit configured to reduce the temperature of the helium gas raw material to a first temperature; a second cooling unit configured to receive the helium gas raw material cooled having the first temperature and reduce the temperature of the helium gas raw material having the first temperature to a second temperature; an impurity separation unit configured to receive the helium gas raw material having the second temperature and removing a first impurity from the helium gas raw material having the second temperature, wherein the freezing point of the first impurity is not lower than the second temperature; an impurity adsorption unit configured to receive the helium gas raw material which the first impurity has been separated, and configured to adsorb a second impurity in the helium gas raw material to obtain purified helium gas; and an outlet configured to output the purified helium gas.

Description

Helium purification device and method for purifying helium

The present invention relates to a purification device and a purification method, and more specifically, to a helium purification device and a method for purifying helium.

Helium is a scarce and high-cost consumable resource. It is widely used in many fields such as medicine, energy and space research, and its annual consumption rate continues to rise at a rate of about 10%. In many facilities, liquid helium is widely used for ultra-low temperature cooling of large equipment, including superconducting magnets, superconducting radio frequency resonance cavities, and MRI. However, after the used liquid helium is vaporized through phase change, it may carry impurities such as moisture, oxygen, oil and nitrogen. The freezing point of these impurities is higher than that of liquid helium and may crystallize and solidify. Solidified impurities will directly affect the performance and operation of the liquid helium manufacturing system for helium recovery and re-production and the cryogenic system using liquid helium, including changing the flow characteristics, damaging the cold box or moving parts (such as turbines, etc.) in the cryogenic system, and thus reducing the overall operating efficiency. Therefore, it is critical to effectively remove impurities to extend the service life of the cryogenic system.

One problem with traditional helium purification methods is the low efficiency in removing trace impurities. Therefore, helium purification devices and methods for purifying helium need to be further improved to obtain purified helium with higher purification efficiency and low loss to support the widespread application of liquid helium.

An embodiment of the present invention relates to a helium purification device. The helium purification device includes: an inlet for receiving helium; a first cooling unit, which is configured to reduce the temperature of the helium to a first temperature; a second cooling unit, which is configured to receive the helium cooled to the first temperature and reduce the temperature of the helium having the first temperature to a second temperature; an impurity separation unit, which is configured to receive the helium cooled to the second temperature and separate a first impurity from the helium having the second temperature, wherein the freezing point of the first impurity is not lower than the second temperature; an impurity adsorption unit, which is configured to receive the helium from which the first impurity is separated and adsorb a second impurity in the helium to obtain purified helium; and an outlet, which is configured to output the purified helium.

An embodiment of the present invention relates to a method for purifying helium. The method includes: receiving a helium raw material; lowering the temperature of the helium raw material to a first temperature; separating water from the helium raw material cooled to the first temperature; lowering the temperature of the helium raw material having the first temperature to a second temperature; separating a first impurity from the helium raw material having the second temperature, wherein the freezing point of the first impurity is higher than the second temperature; adsorbing a second impurity from the helium raw material having the second temperature and from which the first impurity has been separated to obtain purified helium; and raising the temperature of the purified helium.

The following disclosure provides many different embodiments or examples for implementing the different features of the present invention. Specific examples of components and configurations are described below to simplify the present invention. Of course, these are only examples and are not intended to be limiting. For example, in the following description, a first component is formed above a second component or a first component is formed on a second component, which may include an embodiment in which the first component and the second component are in direct contact, and may also include an embodiment in which an additional component is formed between the first component and the second component, so that the first component and the second component may not be in direct contact. In addition, the present disclosure may repeat component symbols and/or letters in various examples. This repetition is for the purpose of simplification and clarity, and does not itself represent the relationship between the various embodiments and/or configurations discussed.

Additionally, for ease of description, spatially relative terms such as "below," "beneath," "down," "above," "upper," and the like may be used herein to describe the relationship of one element or component to another element or components as depicted in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be in other orientations (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

As used herein, terms such as "first," "second," and "third" describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another. When used herein, the terms "first," "second," and "third" do not imply a sequence or order unless clearly indicated by the context.

The present invention provides a helium purification device and a method for purifying helium. In some embodiments, the helium purification device of the present invention purifies helium by physical means and can quickly purify a large amount of helium in a short time, which is beneficial to support the wide application of helium.

FIG1 is a schematic diagram of a helium purification device 100 according to some embodiments of the present invention. Referring to FIG1 , the helium purification device 100 of the present invention includes an inlet 110, a first cooling unit 121, a first heating unit 122, a second cooling unit 150, an impurity separation unit 160, an impurity adsorption unit 170, and an outlet 180. In some embodiments, the helium purification device 100 further includes an outer shell 101, a shell-and-tube heat exchanger 130, and a liquid nitrogen storage tank 140.

In some embodiments, the housing 101 is used to accommodate the first cooling unit 121, the first heating unit 122, the shell-and-tube heat exchanger 130, the liquid nitrogen storage tank 140, the second cooling unit 150, the impurity separation unit 160, and the impurity adsorption unit 170. In some embodiments, the inlet 110 is used to receive the helium raw material 200 into the housing 101 of the helium purification device 100, and the outlet 180 is used to output the purified helium 300 out of the housing 101 of the helium purification device 100. In some embodiments, the pressure in the housing 101 is between about 0.00001 bar and about 0.01 bar.

In some embodiments, the first fluid conduit 111 is located in the housing 101 and is configured to communicate the inlet 110 and the first cooling unit 121. The first fluid conduit 111 is used to allow the helium raw material 200 to enter the housing 101 of the helium purification device 100 from outside the housing 101, and is transferred to the first cooling unit 121 through the first fluid conduit 111. In some embodiments, the helium purification device 100 further includes a compressor 102, which is used to increase the internal pressure of the helium raw material 200 and is configured to communicate with the first fluid conduit 111 to facilitate the helium raw material 200 to enter the helium purification device 100. The pressure of the helium feedstock 200 may be increased by the compressor 102 from 1.013 bar in a non-operating state to a pressure of about 3 bar to about 160 bar.

In some embodiments, the helium raw material 200 entering the helium purification device 100 from the inlet 110 includes a first impurity and a second impurity. The first impurity has a freezing point not lower than 77K and may be, for example but not limited to, particles, ice crystals, carbon dioxide, and water. The second impurity is at least one selected from the group consisting of nitrogen, oxygen, hydrocarbons ( _CxHy ), and oil contaminants. In some embodiments _, the first impurity and the second impurity will be substantially removed at different processing stages in the helium purification device 100.

FIG. 2 is a schematic diagram of a coaxial pipe counterflow heat exchanger 120 according to some embodiments of the present invention. FIG. 3 is a perspective view of a tube-in-tube heat exchanger 120 according to some embodiments of the present invention. In some embodiments, referring to FIG. 1 , FIG. 2 and FIG. 3 , the first cooling unit 121 and the first heating unit 122 in the helium purification device 100 are combined in the tube-in-tube heat exchanger 120. The tube-in-tube heat exchanger 120 is used to perform a first heat exchange between the helium raw material 200 and the purified helium 300.

In detail, the first cooling unit 121 is configured to reduce the temperature of the helium raw material 200 to a first temperature. In some embodiments, the first temperature is no more than about 120K. In some embodiments, the first temperature is about 120K to about 80K. Depending on the source of the helium raw material 200 to be purified, its initial temperature may vary. In some examples, the temperature of the helium raw material 200 is reduced from more than 200K to the first temperature, while in other examples, the temperature of the helium raw material 200 is reduced from more than 300K to the first temperature. In some embodiments, the first cooling unit 121 is configured to receive the helium raw material 200, and the first heating unit 122 is configured to receive the purified helium 300. The two are integrated into the tube-in-tube heat exchanger 120 so that the two can perform a first heat exchange, so that in the direction of introducing the helium raw material 200 to be purified into the helium purification device 100, the temperature of the helium raw material 200 will be reduced to the first temperature.

In some embodiments, the tube-in-tube heat exchanger 120 includes two coaxial tubes, one of which is an inner tube and the other is an outer tube, wherein the inner tube is located in the outer tube and the outer tube is sleeved outside the inner tube. Through the tube-in-tube configuration, the helium raw material 200 flowing in the first cooling unit 121 will perform the aforementioned first heat exchange with the purified helium 300 flowing in the first heating unit 122.

In some embodiments, the first cooling unit 121 is configured to allow the helium raw material 200 to enter the inner tube and flow through the compressor 102, and the first heating unit 122 is configured to allow the purified helium 300 to enter the annular space between the inner tube and the outer tube and flow along the second direction X2. The first direction X1 is opposite to the second direction X2. In some embodiments, the first cooling unit 121 is configured to allow the helium raw material 200 to enter the annular space between the inner tube and the outer tube and flow along the first direction X1, and the first heating unit 122 is configured to allow the purified helium 300 to enter the inner tube and flow along the second direction X2. That is, in some embodiments of the present invention, after the helium raw material 200 to be purified enters the helium purification device 100, the helium raw material 200 to be purified will be subjected to a cooling treatment, and before the purified helium 300 leaves the helium purification device 100, the purified helium 300 will be subjected to a heating treatment, and the cooling/heating treatment is achieved by the tube-in-tube configuration of the tube-in-tube heat exchanger 120. In some embodiments, the two coaxial tubes are spiral, the first direction X1 is clockwise or counterclockwise, and the second direction X2 is counterclockwise or clockwise, so that the first direction X1 is opposite to the second direction X2. In some embodiments, to enhance heat exchange efficiency, the length of each coaxial tube is greater than 1 meter.

In some embodiments, the second fluid conduit 112 is located in the housing 101 and is configured to communicate the first cooling unit 121 and the shell-tube heat exchanger 130. The second fluid conduit 112 is used to receive the helium raw material 200 having a first temperature from the first cooling unit 121 and transmit it to the shell-tube heat exchanger 130 through the second fluid conduit 112. In some embodiments, the shell-tube heat exchanger 130 is disposed between the first cooling unit 121 and the second cooling unit 150.

FIG. 4 is a schematic diagram of a vassel and tube heat exchanger 130 according to some embodiments of the present invention. In some embodiments, referring to FIG. 1 and FIG. 4 , the vassel and tube heat exchanger 130 is used to perform a second heat exchange between a helium raw material 200 having a first temperature and a purified helium 300. The vassel and tube heat exchanger 130 includes an outer shell 131 and an inner pipe 132. The inner pipe 132 is accommodated in the outer shell 131, and a flow space 133 is provided between the inner pipe 132 and an inner wall 131a of the outer shell 131. The inner pipe 132 is connected to the impurity adsorption unit 170 to receive the purified helium 300, and the flow space 133 is connected to the second fluid conduit 112 and the first cooling unit 121 to accommodate the helium raw material 200 having a first temperature. In some embodiments, the inner pipe 132 is spiral to increase the contact area between the helium raw material 200 having a first temperature and the outer surface 132a of the inner pipe 132. In some embodiments, when the second heat exchange is performed, the water vapor of the helium raw material 200 having a first temperature will condense or adhere to the inner pipe 132 and the inner wall 131a of the outer shell 131. In some embodiments, the shell-and-tube heat exchanger 130 is configured to remove water from the helium raw material 200 having a first temperature. Therefore, compared with the aforementioned tube-in-tube heat exchanger 120, the purpose of the shell-and-tube heat exchanger 130 is different. The main purpose of the aforementioned tube-in-tube heat exchanger 120 is to adjust the temperature, while the main purpose of the shell-and-tube heat exchanger 130 is to cooperate with the structural design of the shell-and-tube heat exchanger 130 and use the purified helium 300 with a lower temperature to assist in removing water from the helium raw material 200.

In some embodiments, the third fluid conduit 113 is located in the outer shell 101 and is configured to connect the shell-and-tube heat exchanger 130 and the second cooling unit 150. The third fluid conduit 113 is used to receive the helium raw material 200 having a first temperature from the outer shell 131 of the shell-and-tube heat exchanger 130 and transfer the helium raw material 200 having the first temperature to the second cooling unit 150.

In some embodiments, the second cooling unit 150, the impurity separation unit 160, and the impurity adsorption unit 170 operate at or below the second temperature. In some embodiments, the second temperature is not more than about 80K. In some embodiments, the second temperature is not more than about 77K.

FIG5 is a three-dimensional schematic diagram of a helium purification device 100 according to some embodiments of the present invention. In some embodiments, referring to FIG1 and FIG5, the second cooling unit 150, the impurity separation unit 160, and the impurity adsorption unit 170 are disposed in a liquid nitrogen storage tank 140 and immersed in liquid nitrogen 141. In some embodiments, the liquid nitrogen storage tank 140 is used to contain liquid nitrogen 141, and is used to allow the second cooling unit 150, the impurity separation unit 160, and the impurity adsorption unit 170 to be immersed in liquid nitrogen 141 when in a working state. In some embodiments, the second cooling unit 150, the impurity separation unit 160, and the impurity adsorption unit 170 are completely immersed in liquid nitrogen 141 when in a working state. In some embodiments, the liquid nitrogen storage barrel 140 has a multi-layer thermal insulation film 142, and at least one hollow space 143 is included between the outer shell 101 and the multi-layer thermal insulation film 142. Compared with the traditional thermal insulation system, the liquid nitrogen storage barrel 140 with a multi-layer thermal insulation film 142 can reduce the heat flux by three orders of magnitude, so that the consumption of liquid nitrogen 141 is greatly reduced. In some embodiments, the static heat loss of the liquid nitrogen 141 in the liquid nitrogen storage barrel 140 is 55W, and the consumption of liquid nitrogen 141 is 1.25 liters/hour. In some embodiments, the third fluid conduit 113 transports the helium raw material 200 having a first temperature to the second cooling unit 150 located in the liquid nitrogen storage barrel 140.

In some embodiments, the liquid level sensor 144 is disposed in the liquid nitrogen storage tank 140 to detect or measure the liquid level and liquid volume of the liquid nitrogen 141 in the liquid nitrogen storage tank 140. In some embodiments, a plurality of liquid level sensors 144 are disposed in the liquid nitrogen storage tank 140, and the plurality of liquid level sensors 144 may be dispersedly disposed in various locations in the liquid nitrogen storage tank 140, for example but not limited to. In some embodiments, the plurality of liquid level sensors 144 are arranged between the top and the bottom of the liquid nitrogen storage tank 140 along the gravity direction Z.

FIG6 is a schematic diagram of a second cooling unit 150 according to some embodiments of the present invention. In some embodiments, referring to FIG1 and FIG6, the second cooling unit 150 is configured to receive the helium raw material 200 cooled to a first temperature, and reduce the temperature of the helium raw material 200 having the first temperature to a second temperature to form the helium raw material 200 cooled to the second temperature. In some embodiments, the first impurity will condense when cooled in an environment of the second temperature, so the helium raw material 200 cooled to the second temperature may include the condensed first impurity.

In some embodiments, the second cooling unit 150 is a precooler. In some embodiments, the precooler includes a spirally wound pipeline. In some embodiments, the spirally wound pipeline of the second cooling unit 150 is completely immersed in liquid nitrogen 141.

In some embodiments, the fourth fluid conduit 114 is located in the liquid nitrogen storage tank 140 and is configured to communicate the second cooling unit 150 and the impurity separation unit 160. The fourth fluid conduit 114 is used to receive the helium raw material 200 having the second temperature from the second cooling unit 150 and transport the helium raw material 200 having the second temperature to the impurity separation unit 160.

In some embodiments, the impurity separation unit 160 is configured to receive the helium raw material 200 cooled to the second temperature and separate the first impurity from the helium raw material 200 having the second temperature. In some embodiments, the impurity separation unit 160 separates the first impurity from the helium raw material 200 having the second temperature by a physical method. In some embodiments, the impurity separation unit 160 includes a phase separator 161 and a filter 162. In some embodiments, the fourth fluid conduit 114 is used to transport the helium raw material 200 having the second temperature to the impurity separation unit 160. In some embodiments, the fourth fluid conduit 114 is used to transport the helium raw material 200 having the second temperature to the phase separator 161.

FIG7 is a schematic diagram of a phase separator 161 according to some embodiments of the present invention. In some embodiments, referring to FIG1 and FIG7, the phase separator 161 is configured to separate the first impurity from the helium raw material 200 having the second temperature by using a spiral gas flow 163. In some embodiments, the phase separator 161 defines a narrow space 164 extending along the gravity direction Z, and a high-speed rotating spiral gas flow 163 is established in the narrow space 164. The spiral gas flow 163 is used to carry the helium raw material 200 having the second temperature to rotate in a spiral shape at a high speed around the central axis C of the narrow space 164. In some embodiments, the spiral gas flow 163 is used to carry the helium raw material 200 having the second temperature into the phase separator 161 from the top of the narrow space 164, and moves to the bottom of the narrow space 164 along the gravity direction Z while rotating at a high speed, and then flows from the bottom to the top of the narrow space 164 along the central axis C, and flows out of the narrow space 164. Compared with the inertia of the helium raw material 200 having the second temperature, the first impurities, especially the condensed first impurities or the particles containing the first impurities, have a larger inertia due to their larger volume and/or density. When the spiral gas flow 163 carries the helium raw material 200 having the second temperature and rotates at a high speed around the central axis C of the narrow space 164, the condensed first impurities or particles containing the first impurities having a larger inertia are difficult to move along the narrow curve of the spiral gas flow 163, and may even hit the outer wall and fall to the bottom of the narrow space 164, and thus cannot flow out of the narrow space 164, and are thus removed from the helium raw material 200 having the second temperature.

In some embodiments, the fifth fluid conduit 115 is located in the liquid nitrogen storage tank 140 and is configured to communicate the phase separator 161 and the filter 162. The fifth fluid conduit 115 is used to receive the helium raw material 200 having the second temperature from the phase separator 161 and transport the helium raw material 200 having the second temperature to the filter 162. In some embodiments, the fifth fluid conduit 115 is configured in the impurity separation unit 160.

FIG8 is a schematic diagram of a filter 162 according to some embodiments of the present invention. In some embodiments, referring to FIG1 and FIG8 , the filter 162 is configured to separate ice crystals and carbon dioxide (carbon dioxide having a second temperature as a solid) from the helium raw material 200. In some embodiments, the filter 162 includes a filter screen or filter element 165, which may be, for example but not limited to, a single layer or more of a 40-mesh stainless steel wire cloth roll. The length of the filter 162 may be more than 10 mm. In some embodiments, the filter 162 includes an inlet 166 located at the top and an outlet 167 located at the side. The inlet 166 is connected to the interior of the filter element 165 and is configured to allow the helium raw material 200 with the second temperature to enter the filter element 165. The outlet 167 is located outside the filter element 165 and is configured to allow the helium raw material 200 with the second temperature to leave the filter element 165. The inlet 166 and the outlet 167 ensure that ice crystals and carbon dioxide are intercepted by the filter element 165.

In some embodiments, the sixth fluid conduit 116 is located in the liquid nitrogen storage tank 140 and is configured to communicate the impurity separation unit 160 and the impurity adsorption unit 170. The sixth fluid conduit 116 is used to receive the helium raw material 200 having the second temperature from the impurity separation unit 160 and transport the helium raw material 200 having the second temperature to the impurity adsorption unit 170. In some embodiments, the sixth fluid conduit 116 is used to transport the helium raw material 200 having the second temperature from the filter 162 to the impurity adsorption unit 170. The sixth fluid conduit 116 is configured to connect the outlet 167 of the filter 162 and the impurity adsorption unit 170.

The impurity adsorption unit 170 is configured to receive the helium raw material 200 from which the first impurity is separated and cooled to the second temperature, and to adsorb the second impurity in the helium raw material 200 to obtain purified helium 300. The impurity adsorption unit 170 is used to perform low-temperature adsorption on the helium raw material 200 cooled to the second temperature. In some embodiments, the impurity adsorption unit 170 includes an adsorbent 171, which is a core component for removing impurities from the helium raw material 200 by physical adsorption under low temperature conditions. The purity of the purified helium 300 is greater than 99.99%. In some embodiments, the purity of the purified helium 300 is greater than 99.9995%.

FIG9 is an exploded view of an impurity adsorption unit 170 according to some embodiments of the present invention. In some embodiments, referring to FIG1 and FIG9 , the impurity adsorption unit 170 includes a barrel 172 for containing the adsorbent in addition to the adsorbent 171. In some embodiments, the adsorbent 171 is selected from the following groups alone or in combination: activated alumina, molecular sieve, silica gel, and activated carbon. In some embodiments, the impurity adsorption benefit of using granular activated carbon with a high BET (Brunauer-Emmett-Teller) specific surface area and a low bulk density as adsorbent 171 is relatively obvious. The high BET specific surface area of these granular activated carbons allows more micropores for gas adsorption, while the low bulk density reduces the weight of the adsorption bed. The regeneration temperature of the activated carbon is lower than that of other adsorbents, and it is easier and faster to reactivate when saturated. In an environment of low temperature and high pressure, the nitrogen adsorption isotherm of the granular activated carbon is better than that of commercially available molecular sieves, silica gel and activated alumina. In addition, the granular form of the granular activated carbon has better adsorption performance at low temperatures than other granular activated carbons. After the helium raw material 200 cooled to the second temperature enters the inlet of the barrel 172, the helium raw material 200 cooled to the second temperature is introduced into the activated carbon barrel through a porous inner conduit for low-temperature adsorption. These holes have the functions of rectification, diversion and diffusion, so that the impurities in the helium raw material 200 cooled to the second temperature can be more effectively adsorbed in a low-temperature environment.

In some embodiments, referring to FIG. 1 , the seventh fluid conduit 117 is located in the liquid nitrogen storage barrel 140 and extends outside the liquid nitrogen storage barrel 140, and is configured such that one end thereof is connected to the barrel 172 to be connected to the impurity adsorption unit 170, and the other end thereof is connected to the inner pipe 132 of the shell-and-tube heat exchanger 130. The seventh fluid conduit 117 is used to receive the purified helium 300 from the impurity adsorption unit 170, and to transport the purified helium 300 to the inner pipe 132 of the shell-and-tube heat exchanger 130 for the second heat exchange. In some embodiments, a sensor 117a is provided on the seventh fluid conduit 117 to sense parameters such as temperature and pressure.

As described above, in some embodiments, the shell-and-tube heat exchanger 130 is used to perform a second heat exchange to raise the temperature of the purified helium 300 from about the second temperature to about the first temperature. The inner pipe 132 is used to receive the purified helium 300 and raise the temperature of the purified helium 300 flowing through the inner pipe 132 from about the second temperature to about the first temperature.

In some embodiments, referring to FIG. 1 , the eighth fluid conduit 118 is located in the housing 101 and is configured to connect the shell-and-tube heat exchanger 130 and the first temperature increasing unit 122. The eighth fluid conduit 118 is used to receive the purified helium 300 heated to about the first temperature from the shell-and-tube heat exchanger 130, and to transport the purified helium 300 heated to about the first temperature to the first temperature increasing unit 122 for first heat exchange. In some embodiments, the eighth fluid conduit 118 is used to transport the purified helium 300 from the inner pipe 132 of the shell-and-tube heat exchanger 130 to the tube-in-tube heat exchanger 120. In some embodiments, the tube-in-tube heat exchanger 120 is used to raise the temperature of the purified helium 300 from about the first temperature to above the first temperature, for example, to above 120K.

In some embodiments, the ninth fluid conduit 119 is located in the housing 101 and is configured to communicate the outlet 180 with the first heating unit 122. The ninth fluid conduit 119 is used to transport the purified helium 300 heated to above the first temperature to the outside of the housing 101 of the helium purification device 100, providing the purified helium 300 processed by the helium purification device 100.

FIG10 is a flow chart illustrating a method 400 for purifying helium according to some embodiments of the present invention. The method 400 for purifying helium includes several steps: step (401), receiving a helium raw material; step (402), lowering the temperature of the helium raw material to a first temperature; step (403), separating water from the helium raw material cooled to the first temperature; step (404), lowering the temperature of the helium raw material having the first temperature to a second temperature. ; step (405), separating a first impurity from the helium raw material having the second temperature, wherein the freezing point of the first impurity is higher than the second temperature; step (406), adsorbing a second impurity from the helium raw material having the second temperature and from which the first impurity has been separated, to obtain purified helium; and step (407), raising the temperature of the purified helium.

In order to illustrate the concepts of the present invention and the method 400 for purifying helium, various specific embodiments are provided below. However, the present invention is not intended to be limited to specific specific embodiments. In addition, the elements, conditions or parameters illustrated in different specific embodiments can be combined or modified to form different combinations of specific embodiments, as long as the elements, parameters or conditions used do not conflict. For ease of explanation, reference numbers with similar or identical functions and characteristics are repeated in different specific embodiments and drawings. Various operations of the method 400 for purifying helium can use the specific embodiments shown in any of Figures 1 to 9.

In some embodiments, a method 400 of purifying helium includes step 401 , which includes receiving a helium feedstock 200 . The helium raw material 200 may be, for example but not limited to, from cooling devices of large-scale equipment such as superconducting magnets, superconducting radio frequency resonance cavities, and MRIs. In order to allow the used liquid helium (which has undergone phase change and gasification) to be recycled, one of the purposes of the present invention is to remove the impurities contained therein, such as the first impurities and the second impurities mentioned in the aforementioned embodiment, at different stages to obtain purified helium, so as to provide the purified helium to the industry for use directly (for example, directly connected to a liquid helium production facility to be liquefied to directly feed back the purified liquid helium) or indirectly (for example, by transporting the purified helium to a required facility via a transport facility). In some embodiments, the helium raw material 200 is received by the housing 101 and enters the helium purification device 100 through the inlet 110. In some embodiments, the method 400 for purifying helium uses the helium purification device 100 shown in Figure 1. In some embodiments, the helium raw material 200 is at a pressure of about 3 bar to about 160 bar in steps 402 to 407.

In some embodiments, the method 400 for purifying helium includes step 402, which includes reducing the temperature of the helium feedstock 200 to a first temperature. In some embodiments, the first temperature is no more than about 120K. In some embodiments, reducing the temperature of the helium feedstock 200 to the first temperature includes subjecting the helium feedstock 200 to a first heat exchange with the purified helium 300 to reduce the temperature of the helium feedstock 200 from above 200K to the first temperature. In some embodiments, the first heat exchange is performed by a tube-in-tube heat exchanger 120. In some embodiments, reducing the temperature of the helium feedstock 200 to the first temperature includes using a first cooling unit 121 to reduce the temperature of the helium feedstock 200 to the first temperature, and the first cooling unit 121 may have the aspects shown in Figures 1 to 3, for example. In some embodiments, the helium raw material 200 is transported to the first cooling unit 121 through the first fluid conduit 111.

In some embodiments, the method 400 for purifying helium includes step 403, which includes separating water from the helium raw material 200 having a first temperature. In some embodiments, the step of separating water from the helium raw material 200 having a first temperature includes subjecting the helium raw material 200 having a first temperature to a second heat exchange with the purified helium 300. In some embodiments, the separation of water from the helium raw material 200 having a first temperature and the second heat exchange are performed using a shell-and-tube heat exchanger 130. In some embodiments, the shell-and-tube heat exchanger 130 may be, for example, as shown in FIG. 1 and FIG. 4 . In some embodiments, the step of separating water from the helium raw material 200 having a first temperature includes introducing the helium raw material 200 having a first temperature into the shell-and-tube heat exchanger 130 through the second fluid conduit 112.

In some embodiments, after the temperature of the helium raw material 200 is reduced to the first temperature, a second heat exchange is performed to separate water from the helium raw material 200 having the first temperature. In some embodiments, the helium raw material 200 having a first temperature is introduced into the flow space 133 between the outer shell 131 and the inner tube 132 of the shell-and-tube heat exchanger 130, so that the helium raw material 200 having the first temperature contacts the outer surface 132a of the inner tube 132 to perform a second heat exchange. The inner tube 132 contains purified helium 300 to perform a second heat exchange with the helium raw material 200 located outside the inner tube 132; water condensed on the outer surface 132a of the inner tube 132 and the inner wall 131a of the outer shell 131 is collected; and the helium raw material 200 that has undergone the second heat exchange is discharged from the shell-and-tube heat exchanger 130. In some cases, such as at the beginning of the helium purification process, when purified helium 300 has not yet been produced, the helium raw material 200 can be cooled by general condensation instead of by heat exchange.

In some embodiments, after step 403, the method 400 for purifying helium further includes passing the helium raw material 200 after the second heat exchange into the third fluid conduit 113, and the third fluid conduit 113 sends the helium raw material 200 after the second heat exchange to an environment with a second temperature. In some embodiments, the second temperature is not more than about 80K. In some embodiments, after step 403, the method 400 for purifying helium further includes sending the helium raw material 200 after the second heat exchange into the liquid nitrogen storage tank 140 through the third fluid conduit 113, and the third fluid conduit 113 is immersed in liquid nitrogen 141.

In some embodiments, the method 400 for purifying helium includes step 404, which includes reducing the temperature of the helium raw material 200 after the second heat exchange to a second temperature, the second temperature being no more than about 80K, to obtain the helium raw material 200 having the second temperature. In some embodiments, reducing the temperature of the helium raw material 200 after the second heat exchange to the second temperature is performed by the second cooling unit 150. In some embodiments, the helium raw material 200 after the second heat exchange is transported from the shell-and-tube heat exchanger 130 to the second cooling unit 150 through the third fluid conduit 113. In some embodiments, the second cooling unit 150 may be, for example, but not limited to, the embodiment shown in FIG. 1 or FIG. 6.

In some embodiments, steps 404 to 406 are performed at or below the second temperature. In some embodiments, steps 404 to 406 are performed in a liquid nitrogen storage barrel 140. In some embodiments, the state of the liquid nitrogen storage barrel 140 may be, for example, but not limited to, as shown in FIG. 1 and FIG. 5. In some embodiments, the method 400 for purifying helium further includes immersing the second cooling unit 150 in liquid nitrogen 141. In some embodiments, the method 400 for purifying helium further includes detecting or measuring the liquid level and liquid amount of the liquid nitrogen 141 in the liquid nitrogen storage barrel 140, which may be, for example, but not limited to, detected by a liquid level sensor 144 disposed in the liquid nitrogen storage barrel 140.

In some embodiments, the method 400 for purifying helium includes step 405, which includes separating a first impurity from the helium raw material 200 having a second temperature, wherein the freezing point of the first impurity is higher than the second temperature. In some embodiments, the helium raw material 200 having the second temperature is transported from the second cooling unit 150 to the impurity separation unit 160 through the fourth fluid conduit 114. In some embodiments, the method 400 for purifying helium further includes immersing the impurity separation unit 160 in liquid nitrogen 141.

In some embodiments, the first impurity is separated from the helium raw material 200 having the second temperature by using the phase separator 161 and the filter 162. In some embodiments, step 405 includes providing a spiral gas flow in the phase separator 161, and passing the helium raw material 200 having the second temperature into the phase separator 161 and contacting with the spiral gas flow, so that the first impurity or particles containing the first impurity freely fall to the bottom of the phase separator 161. In some embodiments, the helium raw material 200 having the second temperature is transported from the second cooling unit 150 to the phase separator 161 through the fourth fluid conduit 114. In some embodiments, the phase separator 161 can be, for example, but not limited to, the embodiments shown in FIG. 1 and FIG. 7.

In some embodiments, step 405 further includes filtering the helium raw material 200 having a second temperature, and the first impurities include carbon dioxide and ice crystals. In some embodiments, the method 400 for purifying helium further includes passing the helium raw material 200 having a second temperature into the fifth fluid conduit 115, and the fifth fluid conduit 115 transports the helium raw material 200 having a second temperature from the phase separator 161 to the filter 162. In some embodiments, the helium raw material 200 having a second temperature passes through the filter core 165 in the filter 162 to separate the first impurities from the helium raw material 200 having a second temperature. In some embodiments, the filter 162 can be, for example, but not limited to, the embodiments shown in Figures 1 and 8.

In some embodiments, after step 405, the method 400 for purifying helium further includes passing the helium raw material 200 having the second temperature into the sixth fluid conduit 116, and the sixth fluid conduit 116 transports the helium raw material 200 having the second temperature and from which the first impurity has been separated from the impurity separation unit 160 to the impurity adsorption unit 170. In some embodiments, the sixth fluid conduit 116 is immersed in liquid nitrogen 141.

In some embodiments, the method 400 for purifying helium includes step 406, which includes adsorbing a second impurity from the helium raw material 200 from which the first impurity has been separated and which has a second temperature, to obtain purified helium 300. In some embodiments, step 406 uses physical adsorption. In some embodiments, the helium raw material 200 from which the first impurity has been separated and which has a second temperature is passed into the impurity adsorption unit 170, so that the second impurity is adsorbed and then separated from the helium raw material 200. In some embodiments, the helium raw material 200 from which the first impurity has been separated and which has a second temperature is contacted with an adsorbent 171, so that the second impurity is adsorbed by the adsorbent 171, so that the purified helium 300 is obtained. In some embodiments, the method 400 for purifying helium further includes immersing the impurity adsorption unit 170 in liquid nitrogen 141.

In some embodiments, the time required to obtain purified helium 300 by the method 400 of purifying helium is less than 10 seconds. In some embodiments, the time required to obtain purified helium 300 by the method 400 of purifying helium is less than 3 seconds. In some embodiments, the time required to obtain purified helium 300 by the method 400 of purifying helium is less than 1 second.

In some embodiments, the method 400 of purifying helium includes step 407, which includes heating the purified helium 300. In some embodiments, the purified helium 300 is first heated to a first temperature, and then the purified helium 300 having the first temperature is heated to a temperature above 200K.

In some embodiments, after step 406, the purified helium 300 obtained has a second temperature, and the seventh fluid conduit 117 sends the purified helium 300 having the second temperature out of the liquid nitrogen storage tank 140, so that the purified helium 300 is no longer immersed in the liquid nitrogen 141. In some embodiments, step 407 includes performing a second heat exchange between the purified helium 300 having the second temperature and the helium raw material 200 having the first temperature to increase the temperature of the purified helium 300 having the second temperature.

In some embodiments, step 407 includes transporting the purified helium 300 having the second temperature from the impurity adsorption unit 170 to the shell-and-tube heat exchanger 130 through the seventh fluid conduit 117, and performing a second heat exchange with the helium raw material 200 having the first temperature. In some embodiments, the purified helium 300 having the second temperature is transported to the shell-and-tube heat exchanger 130 for temperature increase, for example, the temperature is increased in the inner pipe 132 of the shell-and-tube heat exchanger 130.

In some embodiments, step 407 includes subjecting the purified helium 300 that has undergone the second heat exchange to a first heat exchange after the second heat exchange. In some embodiments, the eighth fluid conduit 118 transports the purified helium 300 that has undergone the second heat exchange from the shell-and-tube heat exchanger 130 to the tube-in-tube heat exchanger 120, and performs the first heat exchange with the helium raw material 200. In some embodiments, the eighth fluid conduit 118 transports the purified helium 300 that has undergone the second heat exchange to the first temperature increasing unit 122 for the first heat exchange. In some embodiments, the purified helium 300 that has undergone the first heat exchange has a temperature of more than 200K. In some embodiments, the ninth fluid conduit 119 transports the purified helium 300 after the first heat exchange to the outside of the housing 101. In some embodiments, the flow rate of the purified helium 300 transported to the outside of the housing 101 is greater than 20 g/s.

As mentioned above, the helium purification device and the method for purifying helium of the present invention include a multi-stage purification process, which uses physical methods to perform low-temperature heat exchange and low-temperature adsorption to achieve low-loss and high-efficiency impurity removal, and obtain high-purity purified helium. At the same time, the purification process can also be carried out at a high helium flow rate (more than 20 grams/second, which can be further increased according to the design of the equipment size), which undoubtedly improves the low efficiency of removing trace impurities in helium in the past.

The above description briefly presents the features of certain embodiments of the present application, so that a person with ordinary knowledge in the art to which the present application belongs can more comprehensively understand the various aspects of the content of the present application. A person with ordinary knowledge in the art to which the present application belongs should understand that he or she can easily use the content of the present application as a basis to design or change other processes and structures to achieve the same purpose and/or achieve the same advantages as the implementation method here. A person with ordinary knowledge in the art to which the present application belongs should understand that these equal implementation methods still belong to the spirit and scope of the content of the present application, and that they can be subjected to various changes, substitutions and modifications without violating the spirit and scope of the content of the present application.

100: Helium purification device 101: Shell 102: Compressor 110: Inlet 111: First fluid conduit 112: Second fluid conduit 113: Third fluid conduit 114: Fourth fluid conduit 115: Fifth fluid conduit 116: Sixth fluid conduit 117: Seventh fluid conduit 117a: Sensor 118: Eighth fluid conduit 119: Ninth fluid conduit 120: Tube-in-tube heat exchanger 121: First cooling unit 122: First heating unit 130: Shell-in-tube heat exchanger 131: Outer shell 131a: Inner wall 132: Inner pipeline 132a: Outer surface 133: flow space 140: liquid nitrogen storage tank 141: liquid nitrogen 142: thermal insulation film 143: hollow space 144: liquid level sensor 150: second cooling unit 160: impurity separation unit 161: phase separator 162: filter 163: spiral airflow 164: narrow space 165: filter element 166: inlet 167: outlet 170: impurity adsorption unit 171: adsorbent 172: barrel 180: outlet 200: helium raw material 300: purified helium 401: step 402: step 403: Step 404: Step 405: Step 406: Step 407: Step C: Central axis X1: First direction X2: Second direction Z: Gravity direction

When reading the accompanying drawings, various aspects of the present invention will be better understood from the following embodiments. It should be noted that, in accordance with standard practice in the industry, the various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

FIG. 1 is a schematic diagram of a helium purification device according to some embodiments of the present invention.

FIG. 2 is a schematic diagram of a tube-in-tube heat exchanger according to some embodiments of the present invention.

FIG. 3 is a perspective view of a tube-in-tube heat exchanger according to some embodiments of the present invention.

FIG. 4 is a schematic diagram of a shell and tube heat exchanger according to some embodiments of the present invention.

FIG5 is a three-dimensional schematic diagram of a helium purification device according to certain embodiments of the present invention.

FIG6 is a schematic diagram of a second cooling unit according to some embodiments of the present invention.

FIG. 7 is a schematic diagram of a phase separator according to some embodiments of the present invention.

FIG. 8 is a schematic diagram of a filter according to some embodiments of the present invention.

FIG. 9 is an exploded view of an impurity adsorption unit according to some embodiments of the present invention.

FIG. 10 is a process flow chart illustrating a method for purifying helium according to certain embodiments of the present invention.

100:Helium purification device

101: Shell

102: Compressor

110:Entrance

111: First fluid conduit

112: Second fluid conduit

113: Third fluid conduit

114: Fourth fluid conduit

115: Fifth fluid conduit

116: Sixth fluid conduit

117: Seventh fluid conduit

117a:Sensor

118: Eighth fluid conduit

119: Ninth fluid conduit

120: Tube-in-tube heat exchanger

121: First cooling unit

122: First heating unit

130: Shell and tube heat exchanger

131: Jacket shell

132: Internal pipe

133:Flow space

140: Liquid nitrogen storage tank

141: Liquid nitrogen

142: Thermal insulation film

143:Hollow Space

144: Liquid level sensor

150: Second cooling unit

160: Impurity separation unit

161: Phase separator

162:Filter

170: Impurity adsorption unit

171: Adsorbent

172: Bucket

180:Exit

200: Helium raw material

300: Purified helium

Z: direction of gravity

Claims (20)

A helium purification device comprises: an inlet for receiving a helium raw material; a first cooling unit, which is configured to reduce the temperature of the helium raw material to a first temperature; a second cooling unit, which is configured to receive the helium raw material cooled to the first temperature, and reduce the temperature of the helium raw material having the first temperature to a second temperature; an impurity separation unit, which is configured to receive the helium raw material cooled to the second temperature, and separate a first impurity from the helium raw material having the second temperature, wherein the freezing point of the first impurity is not lower than the second temperature; an impurity adsorption unit, which is configured to receive the helium raw material from which the first impurity is separated, and to adsorb a second impurity in the helium raw material to obtain a purified helium; A liquid nitrogen storage tank, which is configured so that the second cooling unit, the impurity separation unit and the impurity adsorption unit are arranged in the liquid nitrogen storage tank and immersed in liquid nitrogen in a working state; and an outlet for outputting the purified helium, wherein the first impurity includes ice crystals and carbon dioxide. A helium purification device as described in claim 1, wherein the purity of the purified helium is greater than 99.99%. The helium purification device as described in claim 1 further comprises: A first heating unit, which is disposed between the impurity adsorption unit and the outlet, for heating the purified helium. The helium purification device as described in claim 3, wherein the first cooling unit and the first heating unit are combined in a tube-in-tube heat exchanger, and the tube-in-tube heat exchanger is used to perform a first heat exchange between the helium raw material and the purified helium. The helium purification device as described in claim 1 further comprises: A shell-and-tube heat exchanger disposed between the first cooling unit and the second cooling unit, comprising: An outer shell; and An inner pipeline contained in the outer shell and having a flow space between an inner wall of the outer shell, the inner pipeline being connected to the impurity adsorption unit to receive the purified helium, the flow space being connected to the first cooling unit, and the shell-and-tube heat exchanger being used to perform a second heat exchange between the helium raw material and the purified helium. A helium purification device as described in claim 1, wherein the impurity separation unit comprises: a phase separator configured to separate the first impurity from the helium raw material using a spiral gas flow; and a filter configured to separate the ice crystals and the carbon dioxide from the helium raw material. A helium purification device as described in claim 1, wherein the impurity adsorption unit comprises activated carbon. A helium purification device as described in claim 1, wherein the first temperature is no more than about 120K and is higher than the second temperature. A helium purification apparatus as described in claim 1, wherein the second temperature is not more than about 80K. A method for purifying helium, the method comprising: receiving a helium raw material; reducing the temperature of the helium raw material to a first temperature, the first temperature not exceeding about 120K; separating water from the helium raw material cooled to the first temperature; reducing the temperature of the helium raw material having the first temperature to a second temperature in a liquid nitrogen storage tank; separating a first impurity from the helium raw material having the second temperature in the liquid nitrogen storage tank, wherein the freezing point of the first impurity is higher than the second temperature, and the first impurity includes ice crystals and carbon dioxide; adsorbing a second impurity from the helium raw material having the second temperature and from which the first impurity has been separated in the liquid nitrogen storage tank to obtain purified helium; and The purified helium is heated outside the liquid nitrogen storage tank. The method of claim 10, wherein the second impurity is at least one selected from the group consisting of nitrogen, oxygen, hydrocarbons and oil pollution. The method of claim 10, wherein the helium feedstock comprises a pressure between about 3 bar and about 160 bar during purification. The method as described in claim 10, wherein the step of reducing the temperature of the helium raw material to the first temperature comprises: subjecting the helium raw material to a first heat exchange with the purified helium. The method as described in claim 10, wherein the flow rate of the purified helium gas transported to the outside of the liquid nitrogen storage tank is greater than 20 g/s. The method as described in claim 10, wherein the step of separating water from the helium raw material cooled to the first temperature comprises: subjecting the helium raw material having the first temperature to a second heat exchange with the purified helium. The method of claim 10, wherein the time required to obtain the purified helium by the method of purifying helium is less than 10 seconds. The method as described in claim 15, wherein the second heat exchange comprises: Passing the purified helium into an inner tube in a shell-and-tube heat exchanger; Passing the helium raw material having the first temperature into a flow space between an outer shell and the inner tube of the shell-and-tube heat exchanger so that the helium raw material having the first temperature contacts an outer surface of the inner tube; and Collecting water condensed on the outer surface of the inner tube and an inner wall of the outer shell. The method as described in claim 10, wherein the step of separating the first impurity from the helium raw material having the second temperature comprises: Providing a spiral gas flow in a phase separator; Passing the helium raw material having the second temperature into the phase separator and contacting it with the spiral gas flow, allowing the first impurity to freely fall to a bottom of the phase separator, and the second temperature is not more than about 80K. The method as described in claim 10, wherein the step of separating the first impurity from the helium raw material having the second temperature comprises: Filtering the helium raw material having the second temperature. The method of claim 10, wherein the step of adsorbing the second impurity from the helium raw material having the second temperature and from which the first impurity has been separated uses an impurity adsorption unit.

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