Device and method for refining helium

Abstract

The invention discloses a device and a method for refining helium. The device comprises a first heat exchange cold box, a second heat exchange cold box, a first-section low-temperature refining bed, a second-section low-temperature refining bed, a first-section low-temperature refining bed vacuum pump system, a first-section low-temperature refining bed pressurization system, a second-section low-temperature refining bed vacuum pump system and a second-section low-temperature refining bed pressurization system, and a heating coil is arranged in the second-section low-temperature refining bed. According to the invention, trace impurities which cannot be separated by a preorder device are separated by the two-stage low-temperature refining bed, the filling amount of the refining bed is small, the size of the refining bed is small, indirect heating is adopted, the usage amount of regenerated gas is small, and the loss amount of helium products is small.

Description

Technical Field

[0001] The present invention belongs to the technical field of special gases, and more specifically, relates to an apparatus and method for purifying helium gas. Background Art

[0002] Helium is a very important industrial gas and plays an important role in scientific research, national defense, and economic construction. It has a certain irreplaceability, and many countries have listed it as a strategic material. Due to the unique properties of helium, with a low boiling point of -268.9 °C, it can be used in many important technical fields. For example, liquid helium can be used for cryogenic cooling, as a cleaning medium or pressurized propellant for the liquid hydrogen fuel system in rockets and aerospace. In the fields of maglev trains and superconductors, helium is also indispensable. In addition, helium is widely used as a coolant for superconducting electromagnets in nuclear magnetic resonance imaging equipment in the medical field, as a heat transfer medium in nuclear power generation devices, as a coolant and inert gas protector in optical fiber production, and as a carrier gas for gas chromatography in the field of instrumental analysis. Natural gas is the main source of helium. The helium content in various natural gases in China is relatively low, so a large amount is relied on imports.

[0003] Cryogenic purification is the main means for producing high-purity helium gas. Crude helium gas containing impurities such as nitrogen and methane is passed through an adsorbent bed at low temperature, and the impurities are adsorbed on the bed, producing helium gas with a purity of more than 99.999%. When the adsorption bed is saturated, regeneration is carried out to remove the impurities, and the regeneration gas is returned to the previous process.

[0004] When the crude helium contains trace amounts (tens of ppmv) of neon impurities, although cryogenic purification has a separation effect on neon and the adsorbent can adsorb neon, due to the very similar physical and chemical properties of neon and helium, the previous process cannot separate them, and neon gas will continuously accumulate in the system. In order to discharge the neon gas from the system, at this time, the regeneration gas cannot be returned to the previous process, and the regeneration gas must be discharged. When the impurity concentration of the crude helium gas is high, the cryogenic adsorption bed is large and the amount of regeneration gas used is large. At this time, in order to remove trace amounts of neon, the regeneration gas needs to be discharged, and the ratio of the discharged regeneration gas volume to the product volume exceeds 20%, resulting in a low helium recovery rate of the device. Summary of the Invention

[0005] The object of the present invention is to solve the problems existing in the prior art and provide an apparatus and method for purifying helium gas. This method can purify crude helium gas into high-purity helium gas. The crude helium gas passes through two-stage cryogenic adsorption beds. The first-stage cryogenic adsorption bed removes impurities with high concentration that can be separated by the previous process, and the second-stage adsorption bed removes impurities with low concentration that are difficult to separate by the previous process, producing helium gas with a purity higher than 99.999 mol%.

[0006] To achieve the above object, on the one hand, the present invention provides a device for refining helium gas, which comprises: a first heat exchange cold box, a second heat exchange cold box, a first-stage low-temperature refining bed, a second-stage low-temperature refining bed, a first-stage low-temperature refining bed vacuum pump system, a first-stage low-temperature refining bed pressurization system, a second-stage low-temperature refining bed vacuum pump system, and a second-stage low-temperature refining bed pressurization system; a heating coil is arranged in the second-stage low-temperature refining bed;

[0007] The crude helium gas transmission pipeline is connected to the first material flow port of the first-stage low-temperature refining bed through the first heat exchange cold box; the second material flow port of the first-stage low-temperature refining bed, the second heat exchange cold box, and the first material flow port of the second-stage low-temperature refining bed are connected in sequence; the second material flow port of the second-stage low-temperature refining bed is connected to the product gas output pipeline;

[0008] The discharge pipeline of the first material flow port of the first-stage low-temperature refining bed is divided into two paths. The first path is connected to the first-stage low-temperature refining bed pressurization system and the previous unit in sequence; the second path is connected to the first-stage low-temperature refining bed vacuum pump system, the first-stage low-temperature refining bed pressurization system, and the previous unit in sequence;

[0009] The discharge pipeline of the first material flow port of the second-stage low-temperature refining bed is divided into two paths. The first path is connected to the second-stage low-temperature refining bed pressurization system; the second path is connected to the second-stage low-temperature refining bed vacuum pump system and the second-stage low-temperature refining bed pressurization system in sequence; the outlet pipeline of the second-stage low-temperature refining bed pressurization system is divided into two paths. The first path is connected to the previous unit, and the second path is used as a discharge port;

[0010] The product gas output pipeline is also provided with a branch output pipeline, and the branch output pipeline is respectively connected to the second material flow ports of the first-stage low-temperature refining bed and the second-stage low-temperature refining bed;

[0011] Preferably, the outlet of the previous unit is connected to the inlet of the crude helium gas transmission pipeline.

[0012] In the present invention, when removing impurity gases, the first material flow port of the first-stage low-temperature refining bed is the material flow inlet, and the second material flow port is the material flow outlet; the first material flow port of the second-stage low-temperature refining bed is the material flow inlet, and the second material flow port is the material flow outlet; when performing regeneration treatment, the second material flow port of the first-stage low-temperature refining bed is the material flow inlet, and the first material flow port is the material flow outlet; the second material flow port of the second-stage low-temperature refining bed is the material flow inlet, and the first material flow port is the material flow outlet.

[0013] In the present invention, the pre-stage unit is used to purify the material flow passing through it and then enter the crude helium gas transmission pipeline. Those skilled in the art can set corresponding device components according to the needs of purification and impurity removal. For example, the pre-stage unit includes an oxidative dehydrogenation unit, a cryogenic separation unit, and a refined helium impurity removal unit connected in sequence; the refined helium impurity removal unit includes a membrane separation unit or a PSA unit; through the pre-stage unit, impurities such as hydrogen, nitrogen, methane, and oxygen can be removed.

[0014] According to the present invention, preferably, the first-stage low-temperature refining bed pressurization system includes a first-stage low-temperature refining bed compressor suction tank and a first-stage low-temperature refining bed compressor; the second-stage low-temperature refining bed pressurization system includes a second-stage low-temperature refining bed compressor suction tank and a second-stage low-temperature refining bed compressor;

[0015] The outlet pipeline of the first material flow port of the first-stage low-temperature refining bed is divided into two paths. The first path is sequentially connected to the first-stage low-temperature refining bed compressor suction tank, the first-stage low-temperature refining bed compressor, and the pre-stage unit; the second path is sequentially connected to the first-stage low-temperature refining bed vacuum pump system, the first-stage low-temperature refining bed compressor suction tank, the first-stage low-temperature refining bed compressor, and the pre-stage unit;

[0016] The outlet pipeline of the first material flow port of the second-stage low-temperature refining bed is divided into two paths. The first path is sequentially connected to the second-stage low-temperature refining bed compressor suction tank and the inlet of the second-stage low-temperature refining bed compressor; the second path is sequentially connected to the second-stage low-temperature refining bed vacuum pump system, the second-stage low-temperature refining bed compressor suction tank, and the inlet of the second-stage low-temperature refining bed compressor; the outlet pipeline of the second-stage low-temperature refining bed compressor is divided into two paths. The first path is connected to the pre-stage unit, and the second path is used as an exhaust port.

[0017] According to the present invention, preferably, there are at least two first-stage low-temperature refining beds, and the at least two first-stage low-temperature refining beds are arranged in parallel;

[0018] The first material flow port of each first-stage low-temperature refining bed is connected to the first heat exchange cold box, the outlet pipeline of the first material flow port is divided into the two paths, and the second material flow port is respectively connected to the second heat exchange cold box and the branch output pipeline;

[0019] There are at least two second-stage low-temperature refining beds, and the at least two second-stage low-temperature refining beds are arranged in parallel;

[0020] The first material flow port of each second-stage low-temperature refining bed is connected to the second heat exchange cold box, the outlet pipeline of the first material flow port is divided into the two paths, and the second material flow port is respectively connected to the product gas output pipeline and the branch output pipeline.

[0021] According to the present invention, preferably, the aspect ratio of the second-stage low-temperature refining bed is not less than 3.

[0022] In the present invention, designing the length-diameter ratio of the second-stage low-temperature refining bed to be not less than 3 is beneficial to the uniform heating when using the heating coil to heat the adsorption bed layer in the second-stage low-temperature refining bed.

[0023] According to the present invention, preferably, the first material flow port and the second material flow port of the first-stage low-temperature refining bed are respectively arranged at the bottom and the top of the first-stage low-temperature refining bed;

[0024] The first material flow port and the second material flow port of the second-stage low-temperature refining bed are respectively arranged at the bottom and the top of the second-stage low-temperature refining bed;

[0025] Preferably, the adsorbents used in the first-stage low-temperature refining bed and the second-stage low-temperature refining bed are independently activated carbon or molecular sieve adsorbents.

[0026] In the present invention, the first-stage low-temperature refining bed is filled with adsorbents (such as special activated carbon or molecular sieves, etc.) having a large adsorption capacity for nitrogen, methane, and CO; the second-stage low-temperature refining bed is filled with adsorbents (such as molecular sieves, etc.) having a large adsorption capacity for neon and hydrogen.

[0027] According to the present invention, preferably, the second material flow port of the second-stage low-temperature refining bed is connected to the product gas output pipeline, and the product gas output pipeline passes through the second heat exchange cold box and the first heat exchange cold box.

[0028] In the present invention, the product gas output from the second material flow port of the second-stage low-temperature refining bed enters the product gas output pipeline and then passes through the second heat exchange cold box and the first heat exchange cold box in sequence to realize cold energy recovery.

[0029] According to the present invention, preferably, both the first heat exchange cold box and the second heat exchange cold box are connected to the liquid nitrogen supply pipeline, and the liquid nitrogen supply pipeline is connected to the liquid nitrogen replenishment tank.

[0030] In the present invention, liquid nitrogen is transported through the liquid nitrogen supply pipeline to supply cold energy to the first heat exchange cold box and the second heat exchange cold box.

[0031] In the present invention, valves can be set on the corresponding pipelines according to the material flow situation to control the flow of the material flow.

[0032] On the other hand, the present invention provides a method for refining helium gas. This method uses the above device, and this method includes:

[0033] The crude helium gas is cooled by the first heat exchange cold box, then enters the first-stage low-temperature refining bed for impurity removal treatment, and then is cooled by the second heat exchange cold box and enters the second-stage low-temperature refining bed for further impurity removal treatment to obtain the product gas;

[0034] After the first-stage low-temperature refining bed is saturated in adsorption, it is regenerated. First, the first path of the discharge pipeline of the first material flow port of the first-stage low-temperature refining bed is depressurized. Then, the product gas from the branch pipeline is used to regenerate the first-stage low-temperature refining bed, and the generated regeneration gas enters the previous unit through the second path of the discharge pipeline of the first material flow port of the first-stage low-temperature refining bed;

[0035] After the second-stage low-temperature refining bed is saturated in adsorption, it is regenerated. First, the first path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed is depressurized, and the gas generated by depressurization is discharged through the second path of the outlet of the second-stage low-temperature refining bed booster system; Then, the liquid nitrogen in the jacket of the second-stage low-temperature refining bed is drained, and at the same time, the desorbed gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the first path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; Again, under the heating of the heating coil, desorbed gas is obtained, and the desorbed gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; Finally, under the heating of the heating coil and while purging with the product gas from the branch pipeline, the obtained gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; After the heating coil stops heating, the gas obtained by purging enters the previous unit through the first path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed;

[0036] Preferably, again, when the pressure change of the second-stage low-temperature refining bed is less than 1 kPa / minute, start heating with the heating coil. Under the heating of the heating coil, desorbed gas is obtained, and the desorbed gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; Finally, when the bed layer of the second-stage low-temperature refining bed is heated to -120 to -130 °C, under the heating of the heating coil and while purging with the product gas from the branch pipeline, the obtained gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; When the temperature of the bed layer of the second-stage low-temperature refining bed rises to -40 to -50 °C, the heating coil stops heating. After the heating coil stops heating, the gas obtained by purging enters the previous unit through the first path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed;

[0037] Preferably, the outlet gas of the pre-stage unit returns to the crude helium gas transmission pipeline;

[0038] Preferably, the heating temperature of the heating coil does not exceed 250 °C.

[0039] In the present invention, the heating coil can be electrically heated, or at least one of helium, argon, oxygen, and nitrogen can be used as a heating medium for heating.

[0040] According to the present invention, preferably, the operating temperature of the first-stage low-temperature refining bed is -185 °C to -120 °C, and the operating pressure is 1.0 MPaG to 2.5 MPaG; the operating temperature of the second-stage low-temperature refining bed is -210 °C to -180 °C, and the operating pressure is 1.0 MPaG to 2.5 MPaG;

[0041] Preferably, the impurity removal rate of the impurity removal treatment in the first-stage low-temperature refining bed reaches more than 99%; the removed impurity gases include one or more of nitrogen, methane, oxygen, carbon monoxide, and argon;

[0042] Preferably, the removed impurity gases in the second-stage low-temperature refining bed include neon, hydrogen, and optionally at least one of nitrogen, methane, oxygen, carbon monoxide, and argon.

[0043] In the present invention, impurities such as nitrogen, methane, and CO with relatively high contents are removed in the first-stage low-temperature refining bed to produce helium with a purity of more than 99.99%; trace impurities such as neon and hydrogen are removed in the second-stage low-temperature refining bed to produce helium with a purity of more than 99.999%.

[0044] According to the present invention, preferably, there are at least two of the first-stage low-temperature refining bed and the second-stage low-temperature refining bed;

[0045] When a certain first-stage low-temperature refining bed for the impurity removal treatment reaches saturation, it is switched to other first-stage low-temperature refining beds to continue the impurity removal treatment, and the saturated first-stage low-temperature refining bed is regenerated;

[0046] When a certain second-stage low-temperature refining bed for the further impurity removal treatment reaches saturation, it is switched to other second-stage low-temperature refining beds to continue the further impurity removal treatment, and the saturated second-stage low-temperature refining bed is regenerated.

[0047] The present invention has the following beneficial effects:

[0048] (1) The device of the present invention adopts two-stage low-temperature refining beds to separate according to different amounts and separation characteristics of impurities, and produces helium with a purity higher than 99.999 mol%.

[0049] (2) For impurities in large quantities that can be separated by the previous device, they are separated by a first-stage low-temperature refining bed. The adsorbent loading is large, the size of the refining bed layer is large, the amount of regeneration gas is increased, and the regeneration gas is returned to the previous process, with almost no loss of helium.

[0050] (3) The impurities separated by the first-stage low-temperature refining bed can be adsorbed at a relatively high temperature, and the design conditions of the adsorption bed do not need to be particularly harsh, which is convenient for equipment manufacturing.

[0051] (4) For trace impurities that cannot be separated by the previous device, they are separated by a second-stage low-temperature refining bed. The loading of the refining bed is small, the size of the refining bed is small, indirect heating is adopted, the amount of regeneration gas used is small, and the loss of helium product is small.

[0052] (5) For the second-stage low-temperature refining bed, a targeted adsorbent is used, with high neon adsorption efficiency, high precision, and large capacity. The second-stage low-temperature refining bed can operate at a lower temperature.

[0053] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0054] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features, and advantages of the present invention will become more obvious. Among them, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0055] Figure 1 The schematic structural diagram of the device for refining helium according to an embodiment of the present invention is shown.

[0056] Figure 2 The schematic structural diagram of the device for refining helium according to a comparative example of the present invention is shown.

[0057] Description of the Reference Numerals in the Drawings:

[0058] E-001X First heat exchange cold box, E-002X Second heat exchange cold box,

[0059] D-101A / B First-stage low-temperature refining bed, PK-102 Vacuum pump system for the first-stage low-temperature refining bed, D-103 Compressor suction tank for the first-stage low-temperature refining bed, K-104 Compressor for the first-stage low-temperature refining bed,

[0060] D-201A / B Second-stage low-temperature refining bed, PK-202 Vacuum pump system for the second-stage low-temperature refining bed, D-203 Compressor suction tank for the second-stage low-temperature refining bed, K-204 Compressor for the second-stage low-temperature refining bed

[0061] E-201A / B Heating coil

[0062] 1. Coarse helium gas transmission pipeline 2. Product gas output pipeline 3. Previous unit 4. Liquid nitrogen supply pipeline 5. Branch output pipeline Detailed implementation manners

[0063] The preferred implementation manners of the present invention will be described in more detail below. Although the preferred implementation manners of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the implementation manners set forth herein. On the contrary, these implementation manners are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0064] In the following examples and comparative examples, the composition of the coarse helium gas is shown in Table 1.

[0065] Table 1 Composition of coarse helium gas

[0066]

[0067]

[0068] In the coarse helium gas, the contents of nitrogen and methane are relatively high and are easy to adsorb; the contents of argon and oxygen are relatively low and are also easy to adsorb; the content of hydrogen is low and it is difficult to adsorb; the content of neon is low and it is the most difficult to be adsorbed.

[0069] Examples

[0070] As Figure 1 shown, this example provides a device for purifying helium gas, and the device includes: the first heat exchange cold box E-001X, the second heat exchange cold box E-002X, the first-stage low-temperature purification bed D-101A / B, the second-stage low-temperature purification bed D-201A / B, the first-stage low-temperature purification bed vacuum pump system PK-102, the first-stage low-temperature purification bed boosting system, the second-stage low-temperature purification bed vacuum pump system PK-202, and the second-stage low-temperature purification bed boosting system;

[0071] The first-stage low-temperature purification bed boosting system includes the first-stage low-temperature purification bed compressor suction tank D-103 and the first-stage low-temperature purification bed compressor K-104; the second-stage low-temperature purification bed boosting system includes the second-stage low-temperature purification bed compressor suction tank D-203 and the second-stage low-temperature purification bed compressor K-204; heating coils E-201A / B are arranged in the second-stage low-temperature purification bed D-201A / B;

[0072] The crude helium gas transmission pipeline 1 is connected to the first material flow port of the first-stage low-temperature refining bed D-101A / B through the first heat exchange cold box E-001X; the second material flow port of the first-stage low-temperature refining bed D-101A / B, the second heat exchange cold box E-002X, and the first material flow port of the second-stage low-temperature refining bed D-201A / B are connected in sequence; the second material flow port of the second-stage low-temperature refining bed D-201A / B is connected to the product gas output pipeline 2;

[0073] The discharge pipeline of the first material flow port of the first-stage low-temperature refining bed D-101A / B is divided into two paths. The first path is connected to the suction tank D-103 of the first-stage low-temperature refining bed compressor, the first-stage low-temperature refining bed compressor K-104, and the previous unit 3 in sequence; the second path is connected to the vacuum pump system PK-102 of the first-stage low-temperature refining bed, the suction tank D-103 of the first-stage low-temperature refining bed compressor, the first-stage low-temperature refining bed compressor K-104, and the previous unit 3 in sequence;

[0074] The discharge pipeline of the first material flow port of the second-stage low-temperature refining bed D-201A / B is divided into two paths. The first path is connected to the suction tank D-203 of the second-stage low-temperature refining bed compressor and the inlet of the second-stage low-temperature refining bed compressor K-204 in sequence; the second path is connected to the vacuum pump system PK-202 of the second-stage low-temperature refining bed, the suction tank D-203 of the second-stage low-temperature refining bed compressor, and the inlet of the second-stage low-temperature refining bed compressor K-204 in sequence; the outlet of the second-stage low-temperature refining bed compressor K-204 is divided into two paths. The first path is connected to the previous unit 3, and the second path is used as a discharge port;

[0075] The product gas output pipeline 2 is also provided with a branch output pipeline 5, and the branch output pipeline 5 is respectively connected to the second material flow ports of the first-stage low-temperature refining bed D-101A / B and the second-stage low-temperature refining bed D-201A / B;

[0076] The outlet of the previous unit 3 is connected to the inlet of the crude helium gas transmission pipeline 1.

[0077] Among them, the first material flow port and the second material flow port of the first-stage low-temperature refining bed D-101A / B are respectively arranged at the bottom and top of the first-stage low-temperature refining bed D-101A / B; the first material flow port and the second material flow port of the second-stage low-temperature refining bed D-201A / B are respectively arranged at the bottom and top of the second-stage low-temperature refining bed D-201A / B.

[0078] Among them, there are two first-stage low-temperature refining beds D-101A / B, and the two first-stage low-temperature refining beds D-101A / B are arranged in parallel; the first material flow ports of each of the first-stage low-temperature refining beds D-101A / B are connected to the first heat exchange cold box E-001X, and the outlet pipelines of the first material flow ports are all divided into the two paths, and the second material flow ports are respectively connected to the second heat exchange cold box E-002X and the branch output pipeline 5;

[0079] There are two second-stage low-temperature refining beds D-201A / B, and the two second-stage low-temperature refining beds D-201A / B are arranged in parallel; the first material flow ports of each of the second-stage low-temperature refining beds D-201A / B are connected to the second heat exchange cold box E-002X, and the outlet pipelines of the first material flow ports are all divided into the two paths, and the second material flow ports are respectively connected to the product gas output pipeline 2 and the branch output pipeline 5.

[0080] Among them, the length-diameter ratio of the second-stage low-temperature refining bed D-201A / B is not less than 3. The adsorbent used in the first-stage low-temperature refining bed D-101A / B is activated carbon, and the adsorbent used in the second-stage low-temperature refining bed D-201A / B is a molecular sieve adsorbent.

[0081] Among them, the second material flow port of the second-stage low-temperature refining bed D-201A / B is connected to the product gas output pipeline 2, and the product gas output pipeline 2 passes through the second heat exchange cold box E-002X and the first heat exchange cold box E-001X. The product gas output from the second material flow port of the second-stage low-temperature refining bed D-201A / B enters the product gas output pipeline 2 and then passes through the second heat exchange cold box E-002X and the first heat exchange cold box E-001X in sequence to realize cold energy recovery.

[0082] Among them, both the first heat exchange cold box E-001X and the second heat exchange cold box E-002X are connected to the liquid nitrogen supply pipeline, and the liquid nitrogen supply pipeline is connected to the liquid nitrogen replenishment tank. Liquid is transported through the liquid nitrogen supply pipeline to realize the cold energy supply to the first heat exchange cold box E-001X and the second heat exchange cold box E-002X.

[0083] The method for refining helium gas is carried out by using the above device, and the method includes:

[0084] After the crude helium gas is cooled by the first heat exchange cold box E-001X, it enters the first-stage low-temperature refining bed D-101A / B for impurity removal treatment, and then after being cooled by the second heat exchange cold box E-002X, it enters the second-stage low-temperature refining bed D-201A / B for further impurity removal treatment to obtain the product gas;

[0085] When the first-stage low-temperature refining bed D-101A / B is saturated in adsorption, the first-stage low-temperature refining bed D-101A / B is regenerated. First, the first path of the discharge pipeline of the first material flow port of the first-stage low-temperature refining bed D-101A / B is depressurized. Then, the product gas from the branch pipeline is used to regenerate the first-stage low-temperature refining bed D-101A / B. The generated regeneration gas passes through the second path of the discharge pipeline of the first material flow port of the first-stage low-temperature refining bed D-101A / B, and enters the first-stage low-temperature refining bed compressor suction tank D-103 after being evacuated by the vacuum pump system of the first-stage low-temperature refining bed D-101A / B, and enters the previous unit 3 after being pressurized by the first-stage low-temperature refining bed compressor K-104;

[0086] When the second-stage low-temperature refining bed D-201A / B is saturated in adsorption, it is regenerated. First, pressure relief is carried out through the first path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed D-201A / B, and the gas generated by the pressure relief is discharged through the second path of the outlet of the second-stage low-temperature refining bed compressor K-204. Then, the liquid nitrogen in the jacket of the second-stage low-temperature refining bed D-201A / B is drained, and at the same time, the desorbed gas reaches the second path of the outlet pipeline of the second-stage low-temperature refining bed compressor K-204 through the first path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed D-201A / B and is discharged. Again, when the pressure change of the second-stage low-temperature refining bed is less than 1 kPa / minute, heating starts using the heating coils E-201A / B. Under the heating effect of the heating coils E-201A / B, desorbed gas is obtained. The desorbed gas enters the suction tank D-203 of the second-stage low-temperature refining bed compressor K-204 after being evacuated by the vacuum pump system PK-202 of the second-stage low-temperature refining bed, and is discharged through the second path of its outlet pipeline after being pressurized by the second-stage low-temperature refining bed compressor K-204. Finally, when the bed layer of the second-stage low-temperature refining bed D-201A / B is heated to -120, under the heating effect of the heating coils E-201A / B, the product gas from the branch pipeline is used for purging at the same time. The obtained gas enters the suction tank D-203 of the second-stage low-temperature refining bed compressor after being evacuated by the vacuum pump system PK-202 of the second-stage low-temperature refining bed, and is discharged through the second path of its outlet pipeline after being pressurized by the second-stage low-temperature refining bed compressor K-204. When the temperature of the bed layer of the second-stage low-temperature refining bed D-201A / B rises to -40, the heating coils E-201A / B stop heating. After the heating coils E-201A / B stop heating, the gas obtained by purging enters the suction tank D-203 of the second-stage low-temperature refining bed compressor after being evacuated by the vacuum pump system PK-202 of the second-stage low-temperature refining bed, and then enters the previous unit 3 through the first path of its outlet pipeline after being pressurized by the second-stage low-temperature refining bed compressor K-204;

[0087] The outlet gas of the previous unit 3 returns to the crude helium gas transmission pipeline 1;

[0088] The heating temperature of the heating coils E-201A / B does not exceed 250 °C.

[0089] Among them, when a certain first-stage low-temperature refining bed D-101A / B for impurity removal treatment reaches saturation, it is switched to other first-stage low-temperature refining beds D-101A / B to continue the impurity removal treatment, and the saturated first-stage low-temperature refining bed D-101A / B is regenerated;

[0090] When a certain second-stage low-temperature refining bed D-201A / B for the further impurity removal treatment reaches saturation, it is switched to other second-stage low-temperature refining beds D-201A / B to continue the further impurity removal treatment, and the saturated second-stage low-temperature refining bed D-201A / B is regenerated.

[0091] The pre-stage unit 3 is used to purify the material flow flowing through it and then enter the crude helium gas transmission pipeline 1; hydrogen, nitrogen, methane, oxygen and other impurities can be removed through the pre-stage unit. The pre-stage unit 3 includes an oxidative dehydrogenation unit, a cryogenic separation unit and a membrane separation unit connected in sequence.

[0092] Specifically, the helium gas after the first-stage low-temperature refining adsorption is as shown in the following table:

[0093] Table 2 Composition of helium gas after the first-stage low-temperature refining adsorption

[0094] composition after a period of mol% helium 99.99 nitrogen 0.0072 methane 0.0005 argon 0.0002 oxygen 0.0001 neon 0.0018 hydrogen 0.0002

[0095] In this embodiment, the first-stage low-temperature refining beds D-101A / B mainly remove impurities with large quantities that can be separated by the pre-stage device, and separate them at low temperature (the operating temperature is -180 °C and the operating pressure is 2.0 MPaG). After passing through the first-stage low-temperature refining beds D-101A / B, impurities such as nitrogen, methane, argon, and oxygen are deeply removed. At the same time, the first-stage low-temperature refining beds D-101A / B also remove part of the hydrogen. Since neon cannot be separated by the pre-stage system, neon is concentrated together with helium.

[0096] Due to the large quantity of impurities, a large amount of adsorbent is loaded, the size of the refining bed layer is large, the amount of regeneration gas accounts for about 20% of the total gas volume, and the regeneration gas returns to the pre-stage process with almost no loss of helium;

[0097] The impurities separated by the first-stage refining bed can be adsorbed at a relatively high temperature, and the design conditions of the refining bed do not need to be particularly harsh, which is convenient for equipment manufacturing;

[0098] The product after the second-stage low-temperature refining adsorption is as shown in the following table:

[0099] Table 3 Composition of helium gas product after the second-stage low-temperature refining adsorption

[0100]

[0101]

[0102] For trace impurities that cannot be separated by the previous device, the second-stage low-temperature refining bed D-201A / B separates them at low temperature (the operating temperature is -195°C and the operating pressure is 1.9 MPaG). The refining bed has a small filling volume and a small size, uses indirect heating, has a small amount of regeneration gas, accounting for about 5% of the total feed, has a small loss of helium product, and through the regeneration process described later, the helium loss rate can be controlled below 3%, and the helium recovery rate exceeds 97%.

[0103] The second-stage low-temperature refining bed D-201A / B uses a targeted adsorbent with high adsorption efficiency and large capacity.

[0104] When the second-stage adsorption bed is regenerated, first, the liquid nitrogen in the jacket is drained, and at the same time, the desorbed gas reaches the second-way discharge at the outlet of the second-stage low-temperature refining bed D-201A / B pressurization system through the first path of the first material flow port discharge pipeline of the second-stage low-temperature refining bed D-201A / B; then, a heat medium is introduced into the coil to heat the adsorbent bed layer, and all the desorbed gas of the adsorption bed is discharged from the system under a vacuum state. Then, product helium (with a purity of more than 99.999%) is used to purge the bed layer under a vacuum state, and the purge gas is discharged from the system. During the first half of the purge time, the purge gas is discharged from the device, and during the second half of the purge time, the purge gas returns to the previous device.

[0105] Comparative Example 1

[0106] This comparative example uses the device as shown in Figure 2 The raw material gas entering the first-stage low-temperature refining bed D-101A / B has the same composition as that in Table 1. The difference between this device and the device in Example 1 is that: the example is designed with two-stage low-temperature refining beds, while the comparative example is designed with a single-stage low-temperature refining bed. Correspondingly, Comparative Example 1 does not include the second heat exchange cold box E-002X, the second-stage low-temperature refining bed D-201A / B, the second-stage low-temperature refining bed D-201A / B vacuum pump system PK-202, and the second-stage low-temperature refining bed D-201A / B pressurization system; and the first material flow port discharge pipeline of the first-stage low-temperature refining bed D-101A / B is divided into two paths. The first path is sequentially connected to the first-stage low-temperature refining bed compressor suction tank D-103 and the inlet of the first-stage low-temperature refining bed compressor K-104; the second path is sequentially connected to the first-stage low-temperature refining bed vacuum pump system PK-102, the first-stage low-temperature refining bed compressor suction tank D-103, and the inlet of the first-stage low-temperature refining bed compressor K-104; the outlet of the first-stage low-temperature refining bed compressor K-104 is divided into two paths. The first path is connected to the previous unit 3, and the second path is used as a discharge port; the others are the same as in Example 1.

[0107] The method for refining helium in this comparative example includes the following steps:

[0108] After the crude helium gas is cooled by the first heat exchange cold box E-001X, it enters the first-stage low-temperature refining bed D-101A / B for impurity removal treatment to obtain product gas;

[0109] When the first-stage low-temperature refining bed D-101A / B is saturated with adsorption, the first-stage low-temperature refining bed D-101A / B is regenerated. First, pressure relief is carried out through the first path of the discharge pipeline of the first material flow port of the first-stage low-temperature refining bed D-101A / B, and the gas generated by the pressure relief is discharged through the second path at the outlet of the first-stage low-temperature refining bed compressor K-104; then, the product gas from the branch pipeline is used to regenerate the first-stage low-temperature refining bed D-101A / B, and the generated regeneration gas enters the suction tank D-103 of the first-stage low-temperature refining bed compressor after being evacuated by the vacuum pump system PK-102 of the first-stage low-temperature refining bed, and is discharged through the second path of its outlet pipeline after being pressurized by the first-stage low-temperature refining bed compressor K-104; finally, the product gas from the branch pipeline is used to purge the first-stage low-temperature refining bed D-101A / B, and the generated purge gas passes through the second path of the discharge pipeline of the first material flow port of the first-stage low-temperature refining bed D-101A / B, enters the suction tank D-103 of the first-stage low-temperature refining bed compressor after being evacuated by the vacuum pump system of the first-stage low-temperature refining bed D-101A / B, and enters the previous unit 3 after being pressurized by the first-stage low-temperature refining bed compressor K-104;

[0110] The outlet gas of the previous unit 3 returns to the crude helium gas transmission pipeline 1;

[0111] The previous unit 3 is used to purify the material flow flowing through it and then enter the crude helium gas transmission pipeline 1; impurities such as hydrogen, nitrogen, methane, and oxygen can be removed through the previous unit. The previous unit 3 includes an oxidation dehydrogenation unit, a cryogenic separation unit, and a membrane separation unit connected in sequence.

[0112] Among them, when a certain first-stage low-temperature refining bed D-101A / B for impurity removal treatment reaches saturation, it is switched to other first-stage low-temperature refining beds D-101A / B to continue the impurity removal treatment, and the saturated first-stage low-temperature refining bed D-101A / B is regenerated;

[0113] For the first-stage low-temperature refining bed D-101A / B in the comparative example, two bed layers are built-in. One layer of adsorbent is activated carbon, mainly targeting nitrogen, methane, argon, and oxygen, and the other layer of adsorbent is a molecular sieve adsorbent, mainly targeting neon and hydrogen; the composition of the product helium gas after low-temperature refining is shown in Table 4, and it can be seen that the specifications are basically the same as those in Table 3.

[0114] Table 4 Composition of product helium gas after low-temperature refining adsorption

[0115]

[0116] In this comparative example, the first-stage low-temperature refining bed D-101A / B is separated at low temperature (the operating temperature is -180°C and the operating pressure is 2.0 MPaG). Since there are more impurities to be treated and the adsorption bed has a large volume, the consumption of the regeneration gas is relatively large, accounting for about 25% of the total feed. Due to the need to remove neon, the overall operating temperature of the adsorption bed is relatively low. Especially because the regeneration gas contains neon and the previous device cannot handle it, it must be discharged from the system, so the helium loss rate is relatively high and the helium recovery rate does not exceed 80%.

[0117] As can be seen from the above, the helium recovery rate of the example is 17% higher than that of the comparative example, showing significant advantages.

[0118] The embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An apparatus for purifying helium gas, characterized in that, the apparatus comprises: a first heat exchange cold box, a second heat exchange cold box, a first-stage low-temperature purification bed, a second-stage low-temperature purification bed, a first-stage low-temperature purification bed vacuum pump system, a first-stage low-temperature purification bed pressurization system, a second-stage low-temperature purification bed vacuum pump system and a second-stage low-temperature purification bed pressurization system; a heating coil is arranged in the second-stage low-temperature purification bed; The crude helium gas transmission pipeline is connected to the first material flow port of the first-stage low-temperature purification bed through the first heat exchange cold box; the second material flow port of the first-stage low-temperature purification bed, the second heat exchange cold box and the first material flow port of the second-stage low-temperature purification bed are connected in sequence; the second material flow port of the second-stage low-temperature purification bed is connected to the product gas output pipeline; The discharge pipeline of the first material flow port of the first-stage low-temperature purification bed is divided into two paths. The first path is connected to the first-stage low-temperature purification bed pressurization system and the previous unit in sequence; the second path is connected to the first-stage low-temperature purification bed vacuum pump system, the first-stage low-temperature purification bed pressurization system and the previous unit in sequence; The discharge pipeline of the first material flow port of the second-stage low-temperature purification bed is divided into two paths. The first path is connected to the second-stage low-temperature purification bed pressurization system; the second path is connected to the second-stage low-temperature purification bed vacuum pump system and the second-stage low-temperature purification bed pressurization system in sequence; the outlet pipeline of the second-stage low-temperature purification bed pressurization system is divided into two paths. The first path is connected to the previous unit, and the second path is used as a discharge port; A branch output pipeline is also provided on the product gas output pipeline, and the branch output pipeline is respectively connected to the second material flow ports of the first-stage low-temperature purification bed and the second-stage low-temperature purification bed; Preferably, the outlet of the previous unit is connected to the inlet of the crude helium gas transmission pipeline.

2. The apparatus according to claim 1, wherein, the first-stage low-temperature purification bed pressurization system comprises a first-stage low-temperature purification bed compressor suction tank and a first-stage low-temperature purification bed compressor; the second-stage low-temperature purification bed pressurization system comprises a second-stage low-temperature purification bed compressor suction tank and a second-stage low-temperature purification bed compressor; The discharge pipeline of the first material flow port of the first-stage low-temperature purification bed is divided into two paths. The first path is connected to the first-stage low-temperature purification bed compressor suction tank, the first-stage low-temperature purification bed compressor and the previous unit in sequence; the second path is connected to the first-stage low-temperature purification bed vacuum pump system, the first-stage low-temperature purification bed compressor suction tank, the first-stage low-temperature purification bed compressor and the previous unit in sequence; The discharge pipeline of the first material flow port of the second-stage low-temperature purification bed is divided into two paths. The first path is connected to the second-stage low-temperature purification bed compressor suction tank and the inlet of the second-stage low-temperature purification bed compressor in sequence; the second path is connected to the second-stage low-temperature purification bed vacuum pump system, the second-stage low-temperature purification bed compressor suction tank and the inlet of the second-stage low-temperature purification bed compressor in sequence; the outlet pipeline of the second-stage low-temperature purification bed compressor is divided into two paths. The first path is connected to the previous unit, and the second path is used as a discharge port.

3. The apparatus according to claim 1 or 2, wherein, there are at least two first-stage low-temperature purification beds, and the at least two first-stage low-temperature purification beds are arranged in parallel; Each first material flow port of each section of low-temperature refining bed is connected to the first heat exchange cold box, and the material discharge pipelines of the first material flow ports are all divided into the two paths, and the second material flow ports are respectively connected to the second heat exchange cold box and the branch output pipeline; There are at least two sections of low-temperature refining beds, and the at least two sections of low-temperature refining beds are arranged in parallel; Each first material flow port of each section of low-temperature refining bed is connected to the second heat exchange cold box, and the material discharge pipelines of the first material flow ports are all divided into the two paths, and the second material flow ports are respectively connected to the product gas output pipeline and the branch output pipeline.

4. The device according to any one of claims 1-3, wherein, The length-diameter ratio of the section of low-temperature refining bed is not less than 3.

5. The device according to any one of claims 1-3, wherein, The first material flow port and the second material flow port of the section of low-temperature refining bed are respectively arranged at the bottom and the top of the section of low-temperature refining bed; The first material flow port and the second material flow port of the section of low-temperature refining bed are respectively arranged at the bottom and the top of the section of low-temperature refining bed; Preferably, the adsorbents used in the section of low-temperature refining bed and the section of low-temperature refining bed are each independently activated carbon or molecular sieve adsorbent.

6. The device according to any one of claims 1-3, wherein, The second material flow port of the section of low-temperature refining bed is connected to the product gas output pipeline, and the product gas output pipeline passes through the second heat exchange cold box and the first heat exchange cold box.

7. The device according to claim 1, wherein, Both the first heat exchange cold box and the second heat exchange cold box are connected to the liquid nitrogen supply pipeline, and the liquid nitrogen supply pipeline is connected to the liquid nitrogen replenishment tank.

8. A method for refining helium, which uses the device according to any one of claims 1-7, characterized in that, This method includes: The crude helium gas is cooled by the first heat exchange cold box and then enters the section of low-temperature refining bed for impurity removal treatment, and then is cooled by the second heat exchange cold box and enters the section of low-temperature refining bed for further impurity removal treatment to obtain product gas; When the section of low-temperature refining bed is saturated with adsorption, the section of low-temperature refining bed is regenerated. First, the first path of the material discharge pipeline of the first material flow port of the section of low-temperature refining bed is depressurized, and then the product gas from the branch pipeline is used to regenerate the section of low-temperature refining bed, and the generated regeneration gas enters the previous unit through the second path of the material discharge pipeline of the first material flow port of the section of low-temperature refining bed; When the second-stage low-temperature refining bed is saturated with adsorption, the second-stage low-temperature refining bed is regenerated. First, pressure relief is carried out through the first path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed, and the gas generated by the pressure relief is discharged through the second path of the outlet of the second-stage low-temperature refining bed booster system; then, the liquid nitrogen in the jacket of the second-stage low-temperature refining bed is drained, and at the same time, the desorbed gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the first path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed and is discharged; again, under the heating action of the heating coil, desorbed gas is obtained, and the desorbed gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; finally, under the heating action of the heating coil, and at the same time, the product gas from the branch pipeline is used for purging, and the obtained gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; when the heating of the heating coil stops, the gas obtained by purging enters the previous unit through the first path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; Preferably, again, when the pressure change of the second-stage low-temperature refining bed is less than 1 kPa / minute, the heating coil starts to be heated. Under the heating action of the heating coil, desorbed gas is obtained, and the desorbed gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; finally, when the bed layer of the second-stage low-temperature refining bed is heated to -120 to -130 °C, under the heating action of the heating coil, and at the same time, the product gas from the branch pipeline is used for purging, and the obtained gas reaches the second path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; when the temperature of the bed layer of the second-stage low-temperature refining bed rises to -40 to -50 °C, the heating of the heating coil stops. When the heating of the heating coil stops, the gas obtained by purging enters the previous unit through the first path of the outlet of the second-stage low-temperature refining bed booster system through the second path of the discharge pipeline of the first material flow port of the second-stage low-temperature refining bed; Preferably, the outlet gas of the previous unit returns to the crude helium gas transmission pipeline; Preferably, the heating temperature of the heating coil does not exceed 250 °C.

9. According to the method described in claim 1, wherein, the operating temperature of the first-stage low-temperature refining bed is -185 °C to -120 °C, and the operating pressure is 1.0 MPaG to 2.5 MPaG; the operating temperature of the second-stage low-temperature refining bed is -210 °C to -180 °C, and the operating pressure is 1.0 MPaG to 2.5 MPaG; Preferably, the impurity removal rate of the impurity removal treatment in the first-stage low-temperature refining bed reaches over 99%; the removed impurity gases include one or more of nitrogen, methane, oxygen, carbon monoxide, and argon; Preferably, the removed impurity gases in the second-stage low-temperature refining bed include neon and hydrogen, and optionally at least one of nitrogen, methane, oxygen, carbon monoxide, and argon.

10. The method according to claim 1, wherein, both the first-stage low-temperature refining bed and the second-stage low-temperature refining bed are at least two; when a certain first-stage low-temperature refining bed for the impurity removal treatment reaches saturation, switch to other first-stage low-temperature refining beds to continue the impurity removal treatment, and the saturated certain first-stage low-temperature refining bed is regenerated; when a certain second-stage low-temperature refining bed for the further impurity removal treatment reaches saturation, switch to other second-stage low-temperature refining beds to continue the further impurity removal treatment, and the saturated certain second-stage low-temperature refining bed is regenerated.

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