Helium recovery and purification system

Abstract

The helium recovery and purification system comprises a raw material gas port, a low-purity helium filling port, a high-purity helium filling port, a gas water bath heater, a first proportioning valve, a medium-pressure dryer, a balloon, a first-stage purifier and a second-stage purifier, an inlet of the gas water-bath heater is connected with a raw material gas port; the outlet is connected with the inlet of the medium-pressure dryer through a first proportioning valve; an outlet of the medium-pressure dryer is connected with the primary purifier; the primary purifier is connected with the air bag; an outlet of the airbag is connected with an inlet of the helium compressor; an outlet of the helium compressor is connected with an inlet of the high-pressure dryer; an outlet of the high-pressure dryer is divided into two branches, one branch is connected with the low-purity helium filling port, and the other branch is connected with the secondary purifier; and the secondary purifier is connected with the high-purity helium filling port. According to the invention, the problem of helium waste in the leak detection process of the high-pressure seamless hydrogen / helium cylinder is solved, and two purification schemes can be flexibly switched according to field requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of gas purification, and particularly to a helium recovery and purification system. Background Art

[0002] Helium (He) is a noble gas with unique physical and chemical properties. As an indispensable gas source for helium mass spectrometry leak detection, it is widely used in the field of leak detection of high-pressure seamless hydrogen / helium gas cylinders. Currently, the waste helium gas (helium purity 3% - 10%) after leak detection is basically directly discharged.

[0003] With the increasing global shortage of helium resources, more and more attention has been paid to helium recovery and purification technologies. The helium recovery and purification refer to separating and purifying helium from a mixed gas, and common technologies include the following:

[0004] 1. Low-temperature condensation separation technology: Utilize the boiling point differences of different gases to separate helium through low-temperature condensation and distillation.

[0005] 2. Membrane separation technology: Separate gases based on the different rates at which they pass through a membrane. Helium molecules are smaller and usually pass through the membrane faster.

[0006] 3. Adsorption separation technology: Utilize the different adsorption capacities of adsorbents for different gases to selectively adsorb impurity gases.

[0007] However, the current helium recovery and purification equipment or systems lack flexibility in meeting different usage requirements and cannot be switched according to usage needs. Summary of the Invention

[0008] In order to solve the technical problems existing in the background art, a helium recovery and purification system proposed by the present invention is used to solve the problem of helium waste during the leak detection of high-pressure seamless hydrogen / helium gas cylinders.

[0009] A helium recovery and purification system proposed by the present invention includes: a raw gas inlet, a low-purity helium filling port, a high-purity helium filling port, a gas water bath heater, a first proportional regulating valve, a medium-pressure dryer, a balloon, a primary purifier, and a secondary purifier;

[0010] The inlet of the gas water bath heater is connected to the raw gas port; its outlet is connected to the inlet of the medium-pressure dryer through a first proportional regulating valve; the outlet of the medium-pressure dryer is connected to the primary purifier to purify helium in the raw gas by the primary purifier; the primary purifier is connected to the airbag to discharge the purified helium into the airbag for caching; the outlet of the airbag is connected to the inlet of the helium compressor; the outlet of the helium compressor is connected to the inlet of the high-pressure dryer; the outlet of the high-pressure dryer has two branches. One branch is connected to the low-purity helium filling port through a valve, and the other branch is connected to the secondary purifier through a valve to perform secondary purification on the helium obtained by the primary purifier by the secondary purifier; the secondary purifier is connected to the high-purity helium filling port to convey the purified helium to the high-purity helium filling port.

[0011] Preferably, the primary purifier is a cryogenic condensation purifier, and the cold source of the primary purifier is liquid nitrogen. The primary purifier has a product gas outlet for discharging helium and a liquid nitrogen evaporation gas outlet for discharging liquid nitrogen evaporation gas; a three-channel plate heat exchanger is provided between the medium-pressure dryer and the primary purifier. The three-channel plate heat exchanger has one hot fluid channel and two cold fluid channels; the outlet of the medium-pressure dryer is connected to the primary purifier through the hot fluid channel in the three-channel plate heat exchanger; the product gas outlet of the primary purifier is connected to the airbag through one of the cold fluid channels in the three-channel plate heat exchanger, and its liquid nitrogen evaporation gas outlet is discharged through the other cold fluid channel in the three-channel plate heat exchanger.

[0012] Preferably, the primary purifier includes an outer housing filled with liquid nitrogen and an inner housing disposed inside the outer housing; the outlet of the medium-pressure dryer is connected to the inner housing of the primary purifier through the hot fluid channel in the three-channel plate heat exchanger. The product gas outlet of the primary purifier is communicated with the inner housing, and the liquid nitrogen evaporation gas outlet is communicated with the outer housing. The inner housing is connected to the outer housing through a second proportional regulating valve.

[0013] Preferably, the secondary purifier is a cryogenic condensation purifier, and the cold source of the secondary purifier is liquid nitrogen. The secondary purifier has a product gas outlet for discharging helium and a liquid nitrogen evaporation gas outlet for discharging liquid nitrogen evaporation gas; a two-channel heat exchanger is provided between the high-pressure dryer and the secondary purifier. The two-channel heat exchanger has two fluid channels; the outlet of the high-pressure dryer is connected to the secondary purifier through one of the fluid channels in the two-channel heat exchanger; the product gas outlet of the secondary purifier is connected to the high-purity helium filling port through the other fluid channel in the two-channel heat exchanger.

[0014] Preferably, the two-channel heat exchanger is a double-pipe heat exchanger.

[0015] Preferably, it further includes a nitrogen vent. The liquid nitrogen evaporation gas outlets of the primary purifier and the secondary purifier are respectively connected to the nitrogen vent.

[0016] Preferably, it further includes a liquid nitrogen filling port which is divided into two branches. One branch is connected to the primary purifier through a valve, and the other branch is connected to the secondary purifier through a valve.

[0017] Preferably, the outlet of the medium-pressure dryer is divided into two branches. One branch is connected to the primary purifier through a valve, and the other branch is connected to the airbag through a pressure reducing valve.

[0018] Preferably, the balloon is connected with an oil seal cylinder.

[0019] Preferably, it further includes a purging gas path which is connected to the medium-pressure dryer, high-pressure dryer, primary purifier, and secondary purifier respectively through a No. 2 heater. The input end of the purging gas path is connected to a high-purity nitrogen port, and its output end is connected to a nitrogen vent port.

[0020] In the present invention, first, the raw material gas is heated by a gas water bath heater to avoid damage to the internal components of the No. 1 proportional regulating valve caused by low temperature during large-flow throttling of the No. 1 proportional regulating valve. The raw material gas is regulated by the No. 1 proportional regulating valve so that the back-end pressure is controlled at 0.7 MPag and enters the medium-pressure dryer. The medium-pressure dryer is used to remove trace moisture in the raw material gas. The primary purifier purifies the raw material gas (the purity of the purified helium gas is not more than 85%). The secondary purifier performs secondary purification on the product gas obtained by purification of the primary purifier (the purity of the purified helium gas is generally greater than 85% and less than 97%). The primary purifier and the secondary purifier correspond to a low-purity helium filling port and a high-purity helium filling port respectively. When the required helium purity is not more than 85%, the secondary purifier does not work, and the primary purifier works, and helium gas is output from the low-purity helium filling port. When the required helium is greater than 85%, the secondary purifier is started to perform secondary purification on the helium gas purified by the primary purifier, and then it is output from the high-purity helium filling port. The present invention not only solves the problem of helium waste in the helium leak detection process of high-pressure seamless hydrogen / helium gas cylinders, but also can flexibly switch between two purification schemes according to on-site requirements during specific use. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of a helium recovery and purification system proposed by the present invention. Detailed Embodiments

[0022] Refer to Figure 1 , a helium recovery and purification system proposed by the present invention includes: a raw material gas port 202, a low-purity helium filling port 204, a high-purity helium filling port 205, a nitrogen vent port 206, a liquid nitrogen filling port 207, a gas water bath heater 101, a No. 1 proportional regulating valve 102, a medium-pressure dryer 103, a three-channel plate heat exchanger 104, a primary purifier 105; an airbag 107, an oil seal cylinder 108, a secondary purifier 110, and a two-channel heat exchanger 116.

[0023] The gas water bath heater 101 has an inlet and an outlet. Its inlet is connected to the raw gas port 202 to receive the raw gas input from the raw gas port 202 and heat the received raw gas. Its outlet is connected to the inlet of the medium-pressure dryer 103 via the first proportional regulating valve 102 to remove the moisture in the raw gas by the medium-pressure dryer 103.

[0024] The three-channel plate heat exchanger 104 has one hot fluid channel and two cold fluid channels. The primary purifier 105 is for low-temperature condensation purification, and the cold source of the primary purifier 105 is liquid nitrogen. The primary purifier 105 has a product gas outlet for discharging helium gas and a liquid nitrogen evaporation gas outlet for discharging the liquid nitrogen evaporation gas. The outlet of the medium-pressure dryer 103 is connected to the primary purifier 105 via the hot fluid channel in the three-channel plate heat exchanger 104. The product gas outlet of the primary purifier 105 is connected to the airbag 107 via one of the cold fluid channels in the three-channel plate heat exchanger 104, and its liquid nitrogen evaporation gas outlet is connected to the nitrogen vent 206 via the other cold fluid channel in the three-channel plate heat exchanger 104. The airbag 107 is used for buffering. The outlet of the airbag 107 is respectively connected to the oil seal cylinder 108 and the inlet of the helium compressor 111. The outlet of the helium compressor 111 is connected to the inlet of the high-pressure dryer 114.

[0025] The two-channel heat exchanger 116 is a double-pipe heat exchanger, which has two fluid channels and the two fluid channels are coaxial. The secondary purifier 110 is for low-temperature condensation purification, and the cold source of the secondary purifier 110 is liquid nitrogen. The secondary purifier 110 has a product gas outlet for discharging helium gas and a liquid nitrogen evaporation gas outlet for discharging the liquid nitrogen evaporation gas. The outlet of the high-pressure dryer 114 has two branches. One branch is connected to the low-purity helium filling port 204 via a valve, and the other branch is connected to the secondary purifier 110 via a valve and one of the fluid channels in the two-channel heat exchanger 116. The product gas outlet of the secondary purifier 110 is connected to the high-purity helium filling port 205 via the other fluid channel in the two-channel heat exchanger 116 to deliver the purified helium gas to the high-purity helium filling port 205. The liquid nitrogen evaporation gas outlet of the secondary purifier 110 is connected to the nitrogen vent 206.

[0026] The liquid nitrogen filling port 207 has two branches. One branch is connected to the primary purifier 105 via a valve, and the other branch is connected to the secondary purifier 110 via a valve to respectively fill the primary purifier 105 and the secondary purifier 110 with liquid nitrogen to supplement the liquid nitrogen evaporation inside the two.

[0027] The working principle of the operation is as follows: First, the raw gas is heated to 40°C by the gas water bath heater 101 to prevent damage to the internal components of the first proportional regulating valve 102 due to low temperature during large-flow throttling of the first proportional regulating valve 102. The raw gas at 15 - 70 MPag is adjusted by the first proportional regulating valve 102 so that the pressure at the rear end is controlled at 0.7 MPag and enters the medium-pressure dryer 103. The medium-pressure dryer 103 is mainly used to remove trace moisture in the raw gas to avoid pipeline freezing at low temperatures at the rear end. The gas discharged from the medium-pressure dryer 103 enters the three-channel plate heat exchanger 104. The three-channel plate heat exchanger 104 is provided with three fluid channels, including 1 hot fluid channel (inlet gas) and 2 cold fluid channels (connected to liquid nitrogen evaporation gas and product gas respectively), to utilize the low-temperature product gas and liquid nitrogen evaporation gas for heat exchange with the high-temperature raw gas. After heat exchange, the temperature of the raw gas entering the primary purifier 105 can reach -180°C. The liquid nitrogen evaporation gas returns to room temperature (basically around 23°C) and is vented, and the product gas returns to room temperature (basically around 28°C) and enters the balloon 107 for buffering. The primary purifier 105 mainly uses the low-temperature condensation and freezing method to purify 3 - 10% helium gas to 85% helium gas.

[0028] The balloon 107 is mainly used to buffer the product gas of the primary purifier 105 and is provided with an oil seal cylinder 108. A certain amount of oil is filled in the oil seal cylinder 108 according to the local air pressure. When the pressure in the balloon 107 exceeds 8 Kpag, the helium gas buffered in the balloon 107 is automatically discharged to protect the balloon 107 from damage. When the balloon 107 reaches the high level, the helium compressor 111 is interlocked to start, and the helium gas in the balloon 107 is compressed to 20 MPag and transported to the rear end. When the balloon 107 reaches the low level, the helium compressor 111 is interlocked to stop and wait. The gas discharged from the helium compressor 111 passes through the oil filter 112 to remove oil (if the helium compressor uses a diaphragm machine, there is no oil filter), and then passes through the high-pressure dryer 114 to remove moisture. For Plan 1, the required helium purity is ≯85%, and it can be filled through the 85% helium filling port. For Plan 2, the required helium is greater than 85% and less than 97%. The dried helium gas enters the secondary purifier 110 for secondary purification. The working principle of the secondary purifier 110 is the same as that of the primary purifier 105. The main difference is that the pressure of the secondary purifier 110 is greater than that of the primary purifier 105. The specific parameters are: the working pressure of the primary purifier is 0.7 MPag, and the working pressure of the secondary purifier is 20 MPag. The two-channel heat exchanger 116 exchanges heat between the inlet and outlet gases of the secondary purifier 110 to save energy loss. The product gas of the secondary purifier 110 is filled, stored, and used through the 97% helium filling port. For Plan 1 and Plan 2, they can be flexibly switched according to on-site requirements.

[0029] Further, the primary purifier 105 in this embodiment includes an outer housing filled with liquid nitrogen and an inner housing disposed inside the outer housing; the outlet of the medium-pressure dryer 103 is connected to the inner housing of the primary purifier 105 via the hot fluid channel in the three-channel plate heat exchanger 104. The product gas outlet of the primary purifier 105 is communicated with the inner housing, and the liquid nitrogen evaporation gas outlet is communicated with the outer housing. The inner housing is connected to the outer housing through the second proportional regulating valve 106, so as to stably discharge the liquefied nitrogen in the raw material gas as liquid nitrogen into the primary purifier 105 through the second proportional regulating valve 106 for continued use as a cold source, thereby saving energy.

[0030] In addition, in this embodiment, the outlet of the medium-pressure dryer 103 has two branches. One branch is connected to the primary purifier 105 through a valve, and the other branch is connected to the airbag 107 through a pressure reducing valve 121, so as to recover the residual gas at the front end after pressure relief through the pressure reducing valve 121. In addition, during operation, when the gas remaining at the front end of the medium-pressure dryer 103 cannot be purified, the front-end gas can be depressurized to the airbag 107 through the pressure reducing valve 121. For example, when the low-purity helium gas in the hydrogen / helium gas cylinder is less than 0.7 MPag, its pressure is insufficient to enter the purification. At this time, it can be discharged into the balloon 107 through the pressure reducing valve 121 for caching to avoid helium waste.

[0031] In addition, a purging gas path is provided in the helium recovery and purification system proposed by the present invention. The purging gas path enters the second heater 113 through the high-purity nitrogen port 203, is heated, and then is respectively transported to the medium-pressure dryer 103, the high-pressure dryer 114, the primary purifier 104, and the secondary purifier 110 for purging. The purged nitrogen is vented through the nitrogen vent port 206.

[0032] In addition, a first heater 109, a third heater 115, a fourth heater 118, a fifth heater 119, and a sixth heater 120 are respectively provided to heat corresponding parts in the pipeline.

[0033] In summary, the present invention has the following advantages compared with the prior art:

[0034] 1. Two-stage purification modes are provided and can be flexibly switched according to actual needs;

[0035] 2. When throttling high-pressure and large-flow gases (containing a large amount of nitrogen), using a gas water bath heater can effectively protect the internal components of the rear-end first proportional regulating valve 102 and increase its service life;

[0036] 3. The airbag 107 is provided with an oil seal cylinder 108, which can effectively protect the airbag, avoid the risk of explosion, and is simple to manufacture and low in cost;

[0037] 4. A pressure reducing valve 121 is provided, which can reduce the pressure of the remaining gas (below 0.7 MPag) in the front-end hydrogen / helium cylinder and transport it to the secondary purifier 110 for further purification, reducing helium waste;

[0038] 5. A first proportional regulating valve is provided to stabilize the pressure at the rear end and ensure the purification effect;

[0039] 6. The primary purifier is provided with a second proportional regulating valve 106, which can use the condensed nitrogen as liquid nitrogen and continue to supply it to the primary purifier 105, saving energy.

[0040] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A helium recovery and purification system, characterized in that: include: A raw gas inlet (202), a low-purity helium filling inlet (204), a high-purity helium filling inlet (205), a gas water bath heater (101), a No. 1 proportional regulating valve (102), a medium-pressure dryer (103), a balloon (107), a primary purifier (105) and a secondary purifier (110); The inlet of the gas water bath heater (101) is connected to the raw gas port (202); the outlet thereof is connected to the inlet of the medium pressure dryer (103) via the No. 1 proportional regulating valve (102); the outlet of the medium pressure dryer (103) is connected to the primary purifier (105) so that the primary purifier (105) purifies the helium in the raw gas; the primary purifier (105) is connected to the air bag (107) so that the purified helium is discharged into the air bag (107) buffer; the outlet of the air bag (107) is connected to the inlet of the helium compressor (111); The outlet of the compressor (111) is connected to the inlet of the high-pressure dryer (114); the outlet of the high-pressure dryer (114) is divided into two branches, one of which is connected to the low-purity helium filling port (204) through a valve, and the other branch is connected to the secondary purifier (110) through a valve, so that the helium purified by the primary purifier (105) is secondary purified by the secondary purifier (110); the secondary purifier (110) is connected to the high-purity helium filling port (205) to transport the purified helium to the high-purity helium filling port (205).

2. A helium recovery and purification system according to claim 1, characterized in that: The primary purifier (105) is a low-temperature condensation purification device, and the cold source of the primary purifier (105) is liquid nitrogen. The primary purifier (105) has a product gas outlet for discharging helium and a liquid nitrogen evaporation gas outlet for discharging liquid nitrogen evaporation gas. A three-channel plate heat exchanger (104) is provided between the medium-pressure dryer (103) and the primary purifier (105), and the three-channel plate heat exchanger (104) has a hot fluid channel and two cold fluid channels. The outlet of the medium-pressure dryer (103) is connected to the primary purifier (105) via the hot fluid channel in the three-channel plate heat exchanger (104). The product gas outlet of the primary purifier (105) is connected to the air bag (107) via a cold fluid channel in the three-channel plate heat exchanger (104), and its liquid nitrogen evaporation gas outlet is discharged via another cold fluid channel in the three-channel plate heat exchanger (104).

3. A helium recovery and purification system according to claim 2, characterized in that: The primary purifier (105) comprises an outer shell filled with liquid nitrogen and an inner shell arranged inside the outer shell; the outlet of the medium-pressure dryer (103) is connected to the inner shell of the primary purifier (105) via the hot fluid channel in the three-channel plate heat exchanger (104), the product gas outlet of the primary purifier (105) is connected to the inner shell, the liquid nitrogen evaporation gas outlet is connected to the outer shell, and the inner shell is connected to the outer shell via a No. 2 proportional control valve (106).

4. A helium recovery and purification system according to claim 2, characterized in that: The secondary purifier (110) is a low-temperature condensation purification device, and the cold source of the secondary purifier (110) is liquid nitrogen. The secondary purifier (110) has a product gas outlet for discharging helium gas and a liquid nitrogen evaporation gas outlet for discharging liquid nitrogen evaporation gas. A two-channel heat exchanger (116) is provided between the high-pressure dryer (114) and the secondary purifier (110), and the two-channel heat exchanger (116) has two fluid channels. The outlet of the high-pressure dryer (114) is connected to the secondary purifier (110) via one fluid channel in the two-channel heat exchanger (116); the product gas outlet of the secondary purifier (110) is connected to a high-purity helium filling port (205) via another fluid channel in the two-channel heat exchanger (116).

5. A helium recovery and purification system according to claim 4, characterized in that: The two-channel heat exchanger (116) is a double-tube heat exchanger.

6. A helium recovery and purification system according to claim 4, characterized in that: It also includes a nitrogen vent (206), and the liquid nitrogen vapor outlets of the first-stage purifier (105) and the second-stage purifier (110) are respectively connected to the nitrogen vent (206).

7. A helium recovery and purification system according to claim 1, characterized in that: The invention also comprises a liquid nitrogen filling port (207), wherein the liquid nitrogen filling port (207) is divided into two branches, one of which is connected to the primary purifier (105) via a valve, and the other branch is connected to the secondary purifier (110) via a valve.

8. A helium recovery and purification system according to claim 1, characterized in that: The outlet of the medium-pressure dryer (103) is divided into two branches, one of which is connected to the primary purifier (105) via a valve, and the other is connected to the air bag (107) via a pressure reducing valve (121).

9. A helium recovery and purification system according to claim 1, characterized in that: The balloon (107) is connected to an oil seal tube (108).

10. A helium recovery and purification system according to claim 1, characterized in that: The invention also includes a purge gas circuit, which is connected to the medium-pressure dryer (103), the high-pressure dryer (114), the first-stage purifier (104), and the second-stage purifier (110) respectively via the second heater (113), and the input end of the purge gas circuit is connected to the high-purity nitrogen port (203), and the output end is connected to the nitrogen venting port (206).

Images