Improved crude helium purification system and method

Abstract

The invention relates to the technical field of crude helium purification, in particular to an improved crude helium purification system and method. The crude helium purification system comprises a pressure swing adsorption system, a heat exchanger and a dehydrogenation system which are respectively connected with the pressure swing adsorption system, a dehydration system which is respectively connected with the dehydrogenation system and the heat exchanger, a first-stage condensation separation system which is connected with the heat exchanger, and a first-stage flash evaporation system which is respectively connected with the first-stage condensation separation system and the heat exchanger, the second-stage condensation separation system is connected with the heat exchanger and used in cooperation with the first-stage condensation separation system, and the second-stage flash evaporation system is connected with the second-stage condensation separation system, the heat exchanger and the first-stage flash evaporation system. Low-temperature condensation is carried out twice, low-temperature blockage of the system is avoided, the yield is increased, and therefore the helium extraction energy consumption is reduced; helium dissolved in a liquid phase is recycled by adopting a two-stage low-temperature flash evaporation process, low-temperature blockage of methane is avoided by increasing the separation temperature, meanwhile, helium is recycled to the maximum extent, and dissolution loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of helium extraction from natural gas, in particular to an improved crude helium purification system and method. BACKGROUND

[0002] Crude helium purification is an important link in the process of helium extraction from natural gas, which is responsible for processing crude helium (generally containing He: 50%-70%) to pure helium (generally requiring He>99.995%). The main impurities in crude helium include neon, hydrogen, oxygen, argon, nitrogen, methane, carbon monoxide, carbon dioxide, etc. The crude helium purification process mainly includes catalytic oxidation and dehydrogenation, compression, drying, condensation, adsorption and other processes. The adsorption process includes low-temperature adsorption and pressure swing adsorption.

[0003] Crude helium purification generally uses high-pressure low-temperature condensation adsorption process, which has the advantages of low-temperature adsorption, which can meet the purification needs of various impurities, the purity of the product after adsorption is guaranteed, the product yield is high, and it is suitable for producing high-pressure helium. But the disadvantage is also obvious, mainly in the high consumption of liquid nitrogen and high energy consumption.

[0004] In recent years, the pressure swing adsorption process has gradually replaced the deep cooling adsorption process due to its low energy consumption characteristics when large gas volume and helium liquefaction are required, and has been continuously applied in industry. One of the weaknesses of pressure swing adsorption is that the adsorption removal capacity for oxygen content in the raw gas is significantly weaker than that for other impurities such as nitrogen. How to effectively improve the adaptability of crude helium purification to oxygen is one of the problems that must be considered.

[0005] In addition, due to the complexity of the components of the raw natural gas, crude helium generally also contains trace amounts of hydrocarbons such as methane. Hydrocarbon components have the risk of plugging at low temperatures. How to increase the tolerance of crude helium purification to hydrocarbon components such as methane is the second problem that must be considered.

[0006] In addition to the above component problems, compared with deep cooling adsorption, the desorption gas of pressure swing adsorption has a high helium content. How to effectively recover the dissolved helium in it becomes the third problem that must be considered. SUMMARY

[0007] The purpose of the present application is to provide an improved crude helium purification system and method, which performs low-temperature condensation in two stages to avoid system low-temperature plugging, improve yield, and thus reduce helium extraction energy consumption; uses a two-stage low-temperature flash distillation process to recover helium dissolved in the liquid phase, avoids low-temperature plugging of methane by increasing the separation temperature, and maximizes helium recovery while minimizing loss of dissolved helium.

[0008] The present application is realized by the following technical solutions:

[0009] An improved crude helium purification system, comprising a pressure swing adsorption system, a heat exchanger and a dehydrogenation system connected with the pressure swing adsorption system respectively, a dehydration system connected with the dehydrogenation system and the heat exchanger respectively, a first condensing separation system connected with the heat exchanger, a first flash evaporation system connected with the first condensing separation system and the heat exchanger respectively, a second condensing separation system connected with the heat exchanger and used in cooperation with the first condensing separation system, and a second flash evaporation system connected with the second condensing separation system and the heat exchanger and the first flash evaporation system respectively.

[0010] Further, in order to better realize the present application,

[0011] A recovery booster system is arranged between the pressure swing adsorption system and the dehydrogenation system, and the recovery booster system is communicated with the heat exchanger.

[0012] Further, in order to better realize the present application,

[0013] A heat exchange pipe one connected with the dehydration system at one end and connected with the first condensing separation system at the other end, a heat exchange pipe two connected with the first condensing separation system and the second condensing separation system respectively, a heat exchange pipe three connected with the first flash evaporation system and the second flash evaporation system at one end, a heat exchange pipe four connected with the second condensing separation system at one end and connected with the pressure swing adsorption system at the other end, and a heat exchange pipe five connected with the first flash evaporation system and the second flash evaporation system in liquid phase are arranged in the heat exchanger; the other end of the heat exchange pipe three is connected with the recovery booster system; the other end of the heat exchange pipe five is vented.

[0014] Further, in order to better realize the present application,

[0015] A pipe four connected with one end of the heat exchange pipe three is arranged outside the heat exchanger, and a pipe five connected with the other end of the heat exchange pipe three is arranged outside the heat exchanger; the first flash evaporation system and the second flash evaporation system are communicated with the pipe four respectively; a pressure control valve C is arranged on the pipe five.

[0016] Further, in order to better realize the present application,

[0017] A pipe one is arranged between the recovery booster system and the dehydrogenation system; a raw material crude helium input pipe is arranged on the pipe one.

[0018] Further, in order to better realize the present application,

[0019] A pipe two is arranged between the bottom of the first condensing separation system and the middle part of the first flash evaporation system, and a liquid level control valve A is arranged on the pipe two.

[0020] Further, in order to better realize the present application,

[0021] The bottom of the secondary condensing separation system is provided with a pipeline three between the middle part of the secondary flash system, and a liquid level control valve B is arranged on the pipeline three.

[0022] Further, in order to better realize the present application,

[0023] The heat exchange tube six is further arranged in the heat exchanger, one end of the heat exchange tube six is connected with a vacuum pump system, and the other end is connected with a liquid nitrogen input system.

[0024] Further, in order to better realize the present application, the adsorbent in the pressure swing adsorption system is a molecular sieve adsorbent and a carbon molecular sieve adsorbent.

[0025] A purification method of the improved crude helium purification system,

[0026] The raw material crude helium, desorption gas and recovered helium enter the dehydrogenation system, hydrogen impurities are removed, and mixed gas is formed and enters the dehydration system;

[0027] The mixed gas enters the first condensing separation system after passing through the heat exchanger and is cooled to -180 DEG C to -170 DEG C, and gas phase and liquid phase are separated; the gas phase enters the secondary condensing separation system after passing through the heat exchanger; the liquid phase enters the first flash system for helium separation, and the separated helium enters the recovery pressurization system after passing through the heat exchanger;

[0028] The gas phase entering the secondary condensing separation system is cooled to -205 DEG C to -190 DEG C and is separated to produce gas phase A and liquid phase B; the gas phase A enters the pressure swing adsorption system after passing through the heat exchanger, and the liquid phase B enters the secondary flash system for helium separation, and the separated helium (recovered helium) enters the recovery pressurization system after being heated by the heat exchange tube three;

[0029] The liquid phases separated by the first flash system and the secondary flash system enter the heat exchanger through the heat exchange tube five for cold energy recovery and are vented.

[0030] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0031] The present application is provided with the first condensing separation system, the secondary condensing separation system, the first flash system and the secondary flash system, which cooperate with each other, the first condensing separation system separates and condenses the methane in the crude helium at a higher temperature, and then the oxygen in the crude helium is separated by low-temperature separation to the maximum extent, which can minimize the impurity content entering the pressure swing adsorption device and avoid the low-temperature blocking of methane to the maximum extent; the two-stage low-temperature flash process is used to recover the helium dissolved in the liquid phase, the separation temperature is increased to avoid the low-temperature blocking of methane, and the helium is recovered to the maximum extent and the loss of dissolution is reduced.

[0032] The present application reduces the oxygen content in the crude helium by effectively reducing the oxygen partial pressure in the crude helium at liquid nitrogen temperature, and maximizes the oxygen content in the pressure swing adsorption raw material, and uses a combined adsorbent in the pressure swing adsorption system to enhance the deoxygenation capacity of the conventional nitrogen removal adsorbent. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A process flow diagram of the present application is shown in the figure.

[0034] Figure 2 A process flow diagram of the prior art is shown in the figure

[0035] Wherein 1 is a pressure swing adsorption system, 2 is a heat exchanger, 21 is a heat exchange pipe, 22 is a heat exchange pipe, 23 is a heat exchange pipe, 24 is a heat exchange pipe, 25 is a heat exchange pipe, 26 is a heat exchange pipe, 3 is a dehydrogenation system, 4 is a dehydration system, 5 is a primary condensation separation system, 6 is a primary flash system, 7 is a secondary condensation separation system, 8 is a secondary flash system, 9 is a recovery booster system, 10 is a vacuum pump system, 11 is a pipeline, 12 is a pipeline, 121 is a liquid level control valve A, 13 is a pipeline, 131 is a liquid level control valve B, 14 is a pipeline, 15 is a pipeline, 151 is a pressure control valve C, 16 is a pipeline, 17 is a pipeline, 171 is a liquid level control valve D, 18 is a pipeline, 181 is a liquid level control valve E. DETAILED DESCRIPTION

[0036] The present application will be further described in conjunction with the examples below, but the embodiments of the present application are not limited thereto.

[0037] The present application is realized by the following technical solutions, as shown in Figure 1

[0038] An improved crude helium purification system, comprising a pressure swing adsorption system 1, a heat exchanger 2 and a dehydrogenation system 3 connected to the pressure swing adsorption system 1 respectively, a dehydration system 4 connected to the dehydrogenation system 3 and the heat exchanger 2 respectively, a primary condensation separation system 5 connected to the heat exchanger 2, a primary flash system 6 connected to the primary condensation separation system 5 and the heat exchanger 2 respectively, a secondary condensation separation system 7 connected to the heat exchanger 2 and used in cooperation with the primary condensation separation system 5, and a secondary flash system 8 connected to the secondary condensation separation system 7, the heat exchanger 2 and the primary flash system 6 respectively.

[0039] ​The first-stage condensing separation system 5 and the second-stage condensing separation system 7 cooperate to realize two-stage low-temperature condensing. First, the first-stage condensing separation system 5 is used to condense and separate methane in the crude helium at a relatively high temperature (-170℃ to -180℃), and then the second-stage condensing separation system 7 is used to condense and separate more nitrogen at a lower temperature (-190℃ to -205℃), so that most of the oxygen is removed;

[0040] During the purification, the methane in the crude helium is first condensed and separated by the first-stage condensing separation system 5, and then the oxygen in the crude helium is separated by the second-stage condensing separation system 7 at a low temperature, so that the impurity content entering the pressure swing adsorption device is minimized, and the low-temperature plugging of methane is avoided to the greatest extent. The helium dissolved in the liquid phase separated by the first-stage condensing separation system 5 and the second-stage condensing separation system 7 is recovered by using a two-stage low-temperature flash evaporation process (a first-stage flash evaporation system 6 and a second-stage flash evaporation system 8), so that the low-temperature plugging of methane is avoided by increasing the separation temperature, and the helium is recovered to the greatest extent and the loss of dissolution is reduced;

[0041] The recovery pressurization system 9 is arranged between the pressure swing adsorption system 1 and the dehydrogenation system 3 and communicates with the heat exchanger 2. The recovery pressurization system 9 is used to pressurize the desorbed gas delivered by the pressure swing adsorption system 1 and the recovered helium delivered by the heat exchanger 2, and the pressurized gas is mixed with the crude helium.

[0042] The heat exchanger 2 is provided with a heat exchange pipe one 21 connected to the dehydration system 4 at one end and connected to the first-stage condensing separation system 5 at the other end, a heat exchange pipe two 22 connected to the first-stage condensing separation system 5 and the second-stage condensing separation system 7, respectively, a heat exchange pipe three 23 connected to the first-stage flash evaporation system 6 and the second-stage flash evaporation system 8 at one end, a heat exchange pipe four 24 connected to the second-stage condensing separation system 7 at one end and connected to the pressure swing adsorption system at the other end, and a heat exchange pipe five 25 connected to the first-stage flash evaporation system 6 and the second-stage flash evaporation system 8. The other end of the heat exchange pipe three 23 is connected to the recovery pressurization system 9. The other end of the heat exchange pipe five is vented.

[0043] After the mixed gas after dehydration is heat exchanged in the heat exchange pipe one 21, it enters the first-stage condensing separation system 5 for low-temperature condensing and separation, and is cooled to about -175℃. The gas phase formed after the separation enters the heat exchange pipe two 22, and the gas phase still contains a mixture of helium and nitrogen, a small amount of oxygen, and methane, and the methane is about 1900ppm. The gas phase enters the second-stage condensing separation system 7 after passing through the heat exchange pipe two 22. The separated liquid phase enters the first-stage flash evaporation system 6 for flash evaporation and separation.

[0044] The gas phase is separated again by low-temperature condensation in the secondary condensation separation system 7, and is cooled to about -200 DEG C. The methane partial pressure is already low enough, greatly reducing the risk of low-temperature plugging. The gas phase A and the liquid phase B are separated. At this time, the helium content in the gas phase A is concentrated to 96.9%, and the oxygen content is about 340 ppm. Then, the gas phase A enters the heat exchange tube four 24, is heat-exchanged, and is recovered into the pressure swing adsorption system after entering the heat exchanger 2, greatly reducing the load of the pressure swing adsorption, and making the impurity content in the product helium more stable. The liquid phase B enters the secondary flash evaporation system 8, and is separated by flash evaporation;

[0045] The liquid phase entering the primary flash evaporation system 6 and the liquid phase B entering the secondary flash evaporation system 8 are recovered by flash evaporation to recover the helium dissolved in the liquid phase, form recovered helium, enter the heat exchange tube three 23, and enter the heat exchanger 2 after heat exchange, and then enter the recovery pressurization system 9. The liquid phases after twice flash evaporation are combined, enter the heat exchange tube five 25, and enter the heat exchanger 2 to recover cold energy and be vented, so that the methane impurities have an outlet, and the helium content is about 130 ppm. The overall yield of the process is 99.99%;

[0046] A pipeline four 14 connected to one end of the heat exchange tube three 23 is arranged outside the heat exchanger 2, and a pipeline five 15 connected to the other end of the heat exchange tube three 23 is arranged outside the heat exchanger 2. The top portions of the primary flash evaporation system 6 and the secondary flash evaporation system 8 are communicated with the pipeline four 14, and are combined into the heat exchange tube three 23 through the pipeline four 14. A pressure control valve C151 is arranged on the pipeline five 15, and is used to control the flash evaporation separation pressure of the primary flash evaporation system 6 and the secondary flash evaporation system 8.

[0047] A pipeline two 12 is arranged between the bottom of the primary condensation separation system 5 and the middle portion of the primary flash evaporation system 6, and a liquid level control valve A121 is arranged on the pipeline two 12. A pipeline three 13 is arranged between the bottom of the secondary condensation separation system 7 and the middle portion of the secondary flash evaporation system 8, and a liquid level control valve B131 is arranged on the pipeline three 13.

[0048] Specifically, the helium dissolved in the liquid phase is recovered by flash evaporation in the primary flash evaporation system 6 and the secondary flash evaporation system 8 to form recovered helium, is combined into the pipeline four 14, and then enters the heat exchange tube three 23. After heat exchange in the heat exchanger 2, the recovered helium enters the recovery pressurization system 9.

[0049] A pipe six 16 is arranged outside the heat exchanger 2 and connected with one end of the heat exchange pipe 5; a pipe seven 17 is arranged at the bottom of the first-stage flash evaporation system 6 and communicated with the pipe six 16, and a pipe eight 18 is arranged at the second-stage flash evaporation system 8 and communicated with the pipe six 16; a liquid level control valve D 171 is arranged on the pipe seven 17, and a liquid level control valve E 181 is arranged on the pipe eight 18; thus, the liquid phase separated by the first-stage flash evaporation system 6 and the second-stage flash evaporation system 8 is introduced into the heat exchange pipe five 25 to recover cold energy and then vented;

[0050] A pipe one 11 is arranged between the recovery booster system 9 and the dehydrogenation system 3; and a raw crude helium input pipe is arranged on the pipe one 11;

[0051] The raw crude nitrogen is introduced into the pipe one 11 through the raw crude helium input pipe, mixed with the desorption gas of the recovery booster system 9 transported by the pressure swing adsorption system 1 and the helium booster gas of the recovery booster system 9 introduced into the recovery booster system 9 through the heat exchanger 2, then introduced into the dehydrogenation system 3 for treatment, and then forms a mixed gas introduced into the dehydration system 4; the desorption gas of the pressure swing adsorption system 1 and the recovered helium are introduced into the recovery booster system 9, mixed with the raw crude helium after being boosted, and then the cycle is completed, so that the yield of the process flow is improved;

[0052] A heat exchange pipe six 26 is further arranged in the heat exchanger 2, one end of the heat exchange pipe six 26 is connected with the vacuum pump system 10, and the other end of the heat exchange pipe six 26 is connected with a liquid nitrogen input system;

[0053] By effectively reducing the oxygen partial pressure in the crude helium at the liquid nitrogen temperature, the oxygen content in the raw crude helium of the pressure swing adsorption system 1 is reduced to the maximum extent, and the deoxygenation capacity is enhanced in combination with the pressure swing adsorption system 1.

[0054] Further, the adsorbent in the pressure swing adsorption system 1 is a molecular sieve adsorbent and a carbon molecular sieve adsorbent, the oxygen content in the helium after being removed is less than 1-10 ppm, the requirements of 99.99%-99.999% pure helium for oxygen and nitrogen impurities and the like are met, the needs of helium liquefaction and product sales for helium purity are met, the need of the existing technology for adding a low-temperature adsorption combined process after the pressure swing adsorption is avoided, and the improved process is particularly suitable for the conventional and commonly seen low-helium-content natural gas helium extraction.

[0055] A purification method of the improved crude helium purification system is provided, and the method specifically includes the following steps:

[0056] The raw crude helium, the desorption gas transported by the pressure swing adsorption system 1 and the recovered helium in the recovery booster system 9 are mixed, introduced into the dehydrogenation system 3 to remove hydrogen impurities, and then form a mixed gas introduced into the dehydration system 4;

[0057] The mixed gas enters the first stage condensing separation system 5 through the heat exchange pipe 1 21 to be condensed and separated, and is cooled to -180℃ to -170℃ to separate gas phase and liquid phase; the gas phase enters the heat exchange pipe 2 22 to be heat exchanged, and then enters the second stage condensing separation system 7;

[0058] The liquid phase enters the first stage flash system 6 through the pipe 2 12 to separate helium, and the separated helium is heat exchanged through the heat exchange pipe 3 23 and then enters the recovery pressurization system 9;

[0059] The gas phase entering the second stage condensing separation system 7 is cooled to -205℃ to -190℃ and separated to produce gas phase A and liquid phase B; the gas phase A enters the pressure swing adsorption system 1 after being heat exchanged through the heat exchange pipe 4 24, and the liquid phase B enters the second stage flash system 8 to separate helium, and the separated helium (recovered helium) enters the recovery pressurization system 9 after being heat exchanged through the heat exchange pipe 3 23;

[0060] More nitrogen is condensed through two times of condensing, and most of the oxygen in the helium is removed more strictly; then the residual trace amount of oxygen (generally less than 0.01%-0.1%) enters the pressure swing adsorption system to be removed.

[0061] The pressure swing adsorption system 1 performs adsorption treatment on the gas phase A, and the oxygen in the helium after removal is less than 1-10 ppm, which meets the requirements of 99.99%-99.999% pure helium on oxygen and nitrogen impurities, meets the needs of helium liquefaction and product sales on the purity of helium, avoids the need to increase the low-temperature adsorption combined process after the pressure swing adsorption, and the improved process is particularly suitable for the conventional and common low-helium-content natural gas helium extraction.

[0062] The liquid phase separated by the first stage flash system 6 is collected to the pipe 6 16 together with the liquid phase separated by the second stage flash system 8, and enters the heat exchange pipe 5 25 to recover cold energy and be vented.

[0063] The present application adopts the medium-temperature catalytic oxidation and dehydrogenation process, compared with the method of removing hydrogen in helium by catalytic oxidation in the prior art, the method of removing hydrogen in helium has a high-temperature method with a running temperature of 300-400℃ or above and a medium-temperature method with a temperature of 100-240℃, the high-temperature method can make methane and other components catalytically oxidize to generate carbon dioxide and water, and introduce new impurities that can cause low-temperature blockage, and increase the difficulty of subsequent process treatment; the present application can maximize the hydrogen oxidation reaction purification while inhibiting the methane oxidation reaction.

[0064] Example 1

[0065] The raw material crude helium, desorption gas and recovered helium are mixed and then enter the dehydrogenation system 3 adopting palladium catalysis to remove hydrogen impurities to below 1 ppm, then enter the dehydration system 4 adopting molecular sieve dehydration to remove water to below 0.1 ppm, and then enter the aluminum plate fin heat exchanger 2 to be condensed and separated in two stages,

[0066] The primary condensation is separated by using a primary condensation separation system 5 to cool to about -175℃ at a higher temperature to obtain a gas-liquid two-phase mixture, wherein the gas phase is mainly a mixture of helium and nitrogen, and also has a small amount of oxygen, and the methane is about 1900 ppm; the liquid phase also contains helium and needs to be separated and recovered by flash separation.

[0067] The secondary condensation uses a secondary condensation separation system 7 to cool to about -200℃ at a lower temperature, and since the methane partial pressure after the separation of the primary condensation separation system 5 is already low enough, the risk of low-temperature plugging is greatly reduced, and the gas-liquid separation is further performed in the secondary condensation separation system 7 to form a gas phase A and a liquid phase B, the helium content in the gas phase A is concentrated to 96.9%, and the oxygen is only about 340 ppm, and the material is recovered after the cold energy to enter the subsequent pressure swing adsorption system, which greatly reduces the load of the pressure swing adsorption, and makes the product pure helium more stable.

[0068] The liquid phase after the two-stage flash and the liquid phase B are combined to enter the aluminum plate fin heat exchanger 2 to recover the cold energy and vent, so that the methane impurities have an outlet, and the helium content is about 130 ppm, and the overall yield of the process is 99.99%.

[0069] After the concentrated crude helium after the two-stage low-temperature condensation separation is returned to the aluminum plate fin heat exchanger 2 to recover the cold energy, it enters the pressure swing adsorption system 1, and the adsorbent in the adsorption tower of the system is a combination of molecular sieve adsorbent and carbon molecular sieve adsorbent to form a combined adsorbent bed, and the oxygen in the helium after removal is less than 1-10 ppm, which meets the requirements of 99.99%-99.999% pure helium for oxygen and nitrogen impurities. The desorption gas of the pressure swing adsorption system 1 and the recovered helium after the two-stage flash enter the recovery and pressurization system, are pressurized, and are combined with the raw crude helium to complete the cycle, thereby improving the yield of the process.

[0070] The present application adopts two-stage low-temperature condensation and two-stage pressure reduction flash, the first-stage low-temperature condensation is separated at a higher temperature (-170 to -180℃) to avoid the low-temperature plugging of methane impurities, pre-separates the methane in the raw crude helium, reduces the methane partial pressure in the crude helium entering the subsequent lower-temperature region, avoids the plugging at a lower temperature, makes it possible to further reduce the secondary condensation temperature, thereby reducing the impurity content in the crude helium entering the pressure swing adsorption system, and is beneficial to reducing the processing scale and investment of the pressure swing adsorption system.

[0071] The present application and the existing crude helium purification process are compared, and the comparison results are shown in Table 1.

[0072] Conventional crude helium purification process The present invention Circulating gas flow (Nm3 / h) 38 24 Circulating compression power consumption (kW) 12 8 Pressure swing adsorption system processing scale (Nm3 / h) 98 85 Concentrated helium purity after condensation separation (%) 84.34 96.93 He yield (%) ≥99.9 ≥99.99

[0073] As shown in Table 1, the present application has lower energy consumption, higher purity, and lower circulation gas flow.

[0074] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change of the above embodiment according to the technical essence of the present application falls within the protection scope of the present application.

Claims

1. An improved crude helium purification system characterized by: The application relates to a helium recovery system, which comprises a pressure swing adsorption system (1), a heat exchanger (2) and a dehydrogenation system (3) connected with the pressure swing adsorption system (1) respectively, a dehydration system (4) connected with the dehydrogenation system (3) and the heat exchanger (2) respectively, a first-stage condensing separation system (5) connected with the heat exchanger (2), a first-stage flash evaporation system (6) connected with the heat exchanger (2) and the first-stage condensing separation system (5) respectively, a second-stage condensing separation system (7) connected with the heat exchanger (2) and used in cooperation with the first-stage condensing separation system (5), and a second-stage flash evaporation system (8) connected with the second-stage condensing separation system (7), the heat exchanger (2) and the first-stage flash evaporation system (6) respectively.

2. An improved crude helium purification system as claimed in claim 1, wherein: A recovery pressurization system (9) is arranged between the pressure swing adsorption system (1) and the dehydrogenation system (3), and the recovery pressurization system (9) is communicated with the heat exchanger (2).

3. An improved crude helium purification system as claimed in claim 2, wherein: A heat exchange pipe one (21) with one end connected with the dehydration system (4) and the other end connected with the first-stage condensing separation system (5), a heat exchange pipe two (22) connected with the first-stage condensing separation system (5) and the second-stage condensing separation system (7) respectively, a heat exchange pipe three (23) with one end connected with the first-stage flash evaporation system (6) and the second-stage flash evaporation system (8), a heat exchange pipe four (24) with one end connected with the second-stage condensing separation system (7) and the other end connected with the pressure swing adsorption system (1), and a heat exchange pipe five (25) connected with the first-stage flash evaporation system (6) and the second-stage flash evaporation system (8) are arranged in the heat exchanger (2); the other end of the heat exchange pipe three (23) is connected with the recovery pressurization system (9); and the other end of the heat exchange pipe five (25) is vented.

4. An improved crude helium purification system as claimed in claim 3, wherein: A pipeline four (14) connected with one end of the heat exchange pipe three (23) is arranged outside the heat exchanger (2), and a pipeline five (15) connected with the other end of the heat exchange pipe three (23) is arranged outside the heat exchanger (2); the first-stage flash evaporation system (6) and the second-stage flash evaporation system (8) are communicated with the pipeline four (14) respectively; and a pressure control valve C (151) is arranged on the pipeline five (15).

5. An improved crude helium purification system as claimed in claim 4, wherein: A pipeline one (11) is arranged between the recovery pressurization system (9) and the dehydrogenation system (3); and a raw material crude helium input pipe is arranged on the pipeline one (11).

6. An improved crude helium purification system as claimed in claim 5, wherein: A pipeline two (12) is arranged between the bottom of the first-stage condensing separation system (5) and the middle part of the first-stage flash evaporation system (6), and a liquid level control valve A (121) is arranged on the pipeline two (12); A pipeline three (13) is arranged between the bottom of the second-stage condensing separation system (7) and the middle part of the second-stage flash evaporation system (8), and a liquid level control valve B (131) is arranged on the pipeline three (13).

7. An improved crude helium purification system as claimed in claim 6, wherein: A pipeline six (16) connected with one end of the heat exchange pipe five (15) is arranged outside the heat exchanger (2); a pipeline seven (17) communicated with the pipeline six (16) is arranged at the bottom of the first-stage flash evaporation system (6), and a pipeline eight (18) communicated with the pipeline six (16) is arranged at the second-stage flash evaporation system (8); a liquid level control valve D (171) is arranged on the pipeline seven (17), and a liquid level control valve E (181) is arranged on the pipeline eight (18).

8. An improved crude helium purification system as claimed in claim 1, wherein: A heat exchange tube six (26) is further arranged in the heat exchanger (2), one end of the heat exchange tube six (26) is connected with a vacuum pump system (10) and the other end is connected with a liquid nitrogen input system.

9. An improved crude helium purification system as claimed in claim 1, wherein: The adsorbent in the pressure swing adsorption system (1) is a molecular sieve adsorbent and a carbon molecular sieve adsorbent.

10. A method of purification of a crude helium purification system according to any one of claims 1-9, characterized in that: Specifically comprising the following steps: The crude helium, desorption gas and recovered helium enter a dehydrogenation system (3) to remove hydrogen impurities and form a mixed gas which enters a dehydration system (4); The mixed gas enters a first condensing separation system (5) after passing through the heat exchanger (2) and is cooled to-180℃ to-170℃, and is separated into a gas phase and a liquid phase; the gas phase enters a second condensing separation system (7) after passing through the heat exchanger (2); the liquid phase enters a first flash evaporation system (6) to separate helium, and the separated helium enters a recovery and pressurization system (9) after passing through the heat exchanger (2); The gas phase entering the second condensing separation system (7) is cooled to-205℃ to-190℃ and is separated into a gas phase A and a liquid phase B; the gas phase A enters the pressure swing adsorption system (1) after passing through the heat exchanger (2), and the liquid phase B enters a second flash evaporation system (8) to separate helium, and the separated helium enters the recovery and pressurization system (9) after passing through the heat exchanger (2); The liquid phase separated by the first flash evaporation system (6) and the liquid phase B separated by the second flash evaporation system (8) enter the heat exchanger (2) to recover cold energy and are vented.

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