Backup nitrogen system and air separation unit instrument gas system

Abstract

The utility model discloses a backup nitrogen system and an air separation unit instrument gas system, and relates to the technical field of air separation, the backup nitrogen system comprises a liquid nitrogen storage tank, a gasifier, a heater, a buffer tank, a self-operated pressure reducing valve and an instrument gas main pipeline; a pressure increasing valve is arranged at the output end of the liquid nitrogen storage tank; the input end of the gasifier is communicated with the output end of the liquid nitrogen storage tank through a pipeline; the input end of the heater is communicated with the output end of the gasifier through a pipeline; the input end of the buffer tank is communicated with the output end of the heater through a pipeline; the self-operated pressure reducing valve is arranged at the input end of the buffer tank; the instrument gas main pipeline is used for being communicated with an instrument gas outlet of a molecular sieve of the air separation device, and the output end of the buffer tank is communicated with the instrument gas main pipeline; according to the technical scheme provided by the utility model, the air pressure in the instrument gas main pipeline can be kept stable.

Description

Technical Field

[0001] The utility model relates to the technical field of air separation, in particular to a backup nitrogen system and an instrument gas system of an air separation device. Background Art

[0002] An air separation unit is an industrial equipment device used to separate the various gas components in the air and produce oxygen, nitrogen, argon and other gases of the air components. In an air separation unit, instrument gas is very important. In related technologies, the instrument gas of an air separation unit is provided by a molecular sieve through a pipeline. However, during the operation of the air separation unit, the instrument gas provided by the molecular sieve may fluctuate, resulting in unstable air pressure, thereby affecting the normal use of the air separation unit. Utility Model Content

[0003] The main purpose of the utility model is to provide a backup nitrogen system and an instrument gas system for an air separation device, aiming at maintaining the gas pressure in the instrument gas main pipeline stable.

[0004] To achieve the above purpose, the backup nitrogen system proposed by the utility model includes:

[0005] A liquid nitrogen storage tank, wherein a booster valve is provided at the output end of the liquid nitrogen storage tank;

[0006] A vaporizer, wherein an input end of the vaporizer is connected to an output end of the liquid nitrogen storage tank through a pipeline;

[0007] a heater, wherein an input end of the heater is connected to an output end of the gasifier through a pipeline;

[0008] A buffer tank, wherein an input end of the buffer tank is connected to an output end of the heater through a pipeline;

[0009] A self-operated pressure reducing valve, which is arranged at the input end of the buffer tank; and

[0010] An instrument gas main pipeline is used to communicate with the instrument gas outlet of the molecular sieve of the air separation device, and the output end of the buffer tank is connected to the instrument gas main pipeline.

[0011] In one embodiment, the backup nitrogen system further comprises a heating gas main pipeline and a first pipeline jumper assembly;

[0012] The heating gas main pipeline is used to communicate with the heating gas outlet of the molecular sieve of the air separation device;

[0013] The first pipeline jumper assembly includes a first pipeline jumper tube and a first pipeline jumper valve. The first pipeline jumper tube is used to connect the instrument gas main pipeline and the heating gas main pipeline. The first pipeline jumper valve is arranged on the first pipeline jumper tube.

[0014] In one embodiment, the backup nitrogen system also includes a second pipeline jumper assembly, which includes a second pipeline jumper tube and a second pipeline jumper valve. The second pipeline jumper valve is arranged on the second pipeline jumper tube. One end of the second pipeline jumper tube is connected to the heating gas main pipeline, and the other end of the second pipeline jumper tube is used to connect the liquid oxygen pump sealing gas pipeline and the expander sealing gas pipeline of the air separation unit.

[0015] In one embodiment, the backup nitrogen system also includes a third pipeline jumper assembly, the third pipeline jumper assembly includes a third pipeline jumper tube and a third pipeline jumper valve, the third pipeline jumper valve is arranged on the third pipeline jumper tube, one end of the third pipeline jumper tube is connected to the heating gas main pipeline, and the other end of the third pipeline jumper tube is used to connect to the protection gas main pipeline of the air separation unit.

[0016] In one embodiment, the backup nitrogen system further comprises a bypass manual valve, and the bypass manual valve is arranged at one end of the heating gas main pipeline close to the molecular sieve of the air separation unit.

[0017] In one embodiment, the backup nitrogen system further includes a steam turbine isolation gas pipeline, and the steam turbine isolation gas pipeline is connected to the instrument gas main pipeline.

[0018] In one embodiment, the backup nitrogen system further includes a booster sealed air pipeline, and the booster sealed air pipeline is connected to the instrument gas main pipeline.

[0019] In one embodiment, the backup nitrogen system further comprises a first safety valve, which is arranged on a pipeline between the liquid nitrogen storage tank and the vaporizer; and / or

[0020] The backup nitrogen system further includes a first discharge valve, which is arranged on a pipeline between the liquid nitrogen storage tank and the vaporizer.

[0021] In one embodiment, the backup nitrogen system further comprises a second safety valve, which is disposed on a pipeline between the heater and the buffer tank; and / or

[0022] The backup nitrogen system further includes a second discharge valve, which is disposed on a pipeline between the heater and the buffer tank.

[0023] The utility model also provides an instrument gas system for an air separation device, wherein the instrument gas system for the air separation device comprises the backup nitrogen system as described above.

[0024] In the technical solution of the utility model, the liquid nitrogen in the liquid nitrogen storage tank is pressurized by the booster valve and then enters the vaporizer to become nitrogen, then is heated by the heater, and finally enters the buffer tank. The outlet pressure is adjusted by the self-operated pressure reducing valve to make it slightly lower than the pressure of the instrument gas provided by the molecular sieve. In this way, when the molecular sieve can normally supply the instrument gas, the nitrogen of the backup nitrogen system is not sent out and is in a standby state. When the instrument gas provided by the molecular sieve fluctuates, the backup nitrogen system can play a role in stabilizing the pressure in time to ensure the normal operation of the air separation unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the structure of an embodiment of a backup nitrogen system provided by the utility model;

[0027] Figure 2 This is the connection diagram of the instrument gas main pipeline;

[0028] Figure 3 This is a connection diagram for the heating gas main pipeline and the protective gas main pipeline.

[0029] Description of Figure Numbers:

[0030] 100. Backup nitrogen system; 1. Liquid nitrogen storage tank; 2. Booster valve; 3. Vaporizer; 4. Heater; 5. Buffer tank; 6. Self-operated pressure reducing valve; 7. Instrument gas main pipeline; 8. Heating gas main pipeline; 9. First pipeline jumper valve; 10. Second pipeline jumper valve; 11. Liquid oxygen pump sealing gas pipeline; 12. Expander sealing gas pipeline; 13. Third pipeline jumper valve; 14. Protective gas main pipeline; 15. Bypass hand valve; 16. Steam turbine isolation gas pipeline; 17, supercharger sealing gas pipeline; 18, first safety valve; 19, first discharge valve; 20, second safety valve; 21, second discharge valve; 22, remote pressure gauge; 23, expander reflux valve instrument gas pipeline; 24, expander instrument gas pipeline; 25, liquid oxygen pump cold box instrument gas pipeline; 26, cold box instrument gas pipeline; 27, purification regeneration system instrument gas pipeline; 28, precooling system instrument gas pipeline; 2 9. Instrument gas pipelines for purification system; 30. Instrument gas pipelines for compressor; 31. Auxiliary instrument gas pipelines for turbine; 32. Instrument gas pipelines for bypass filter; 33. Instrument gas pipelines for liquid nitrogen tank area; 34. Instrument gas pipelines for liquid oxygen pipe area; 35. Instrument gas pipelines for liquid argon tank area; 36. Gas pipelines for chromatographs in analysis room; 37. Heating gas pipelines for circulating oxygen pump A; 38. Heating gas pipelines for circulating oxygen pump B; 39. Heating gas pipelines for cryogenic expanders; 40 , low-temperature expander heating gas pipeline; 41. Argon system heating gas pipeline; 42. Liquid argon tank area heating gas pipeline; 43. Liquid nitrogen tank area heating gas pipeline; 44. Liquid oxygen tank area heating gas pipeline; 45. Circulating oxygen pump interlayer protection gas pipeline; 46. Cold box interlayer protection gas pipeline; 47. Expander cold box interlayer gas protection pipeline; 48. Oxygen tank protection gas pipeline; 49. Nitrogen tank protection gas pipeline; 50. Argon tank protection gas pipeline; 51. Molecular sieve.

[0031] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0035] The utility model provides a backup nitrogen system 100 .

[0036] See also Figures 1 to 3 In one embodiment of the utility model, the backup nitrogen system 100 includes a liquid nitrogen storage tank 1, a vaporizer 3, a heater 4, a buffer tank 5, a self-operated pressure reducing valve 6 and an instrument gas main pipeline 7; a booster valve 2 is provided at the output end of the liquid nitrogen storage tank 1; the input end of the vaporizer 3 is connected to the output end of the liquid nitrogen storage tank 1 through a pipeline; the input end of the heater 4 is connected to the output end of the vaporizer 3 through a pipeline; the input end of the buffer tank 5 is connected to the output end of the heater 4 through a pipeline; the self-operated pressure reducing valve 6 is provided at the input end of the buffer tank 5; the instrument gas main pipeline 7 is used to be connected to the instrument gas outlet of the molecular sieve 51 of the air separation unit, and the output end of the buffer tank 5 is connected to the instrument gas main pipeline 7.

[0037] Among them, see Figure 2 The instrument gas main pipeline 7 is connected with the pipelines of various equipments of the air separation unit, including the expander reflux valve instrument gas pipeline 23, the expander instrument gas pipeline 24, the liquid oxygen pump cold box instrument gas pipeline 25, the cold box instrument gas pipeline 26, the purification and regeneration system instrument gas pipeline 27, the precooling system instrument gas pipeline 28, the purification system instrument gas pipeline 29, the compressor instrument gas pipeline 30, the turbine auxiliary instrument gas pipeline 31, the bypass filter instrument gas pipeline 32, the liquid nitrogen tank area instrument gas pipeline 33, the liquid oxygen pipe area instrument gas pipeline 34, the liquid argon tank area instrument gas pipeline 35, the analysis room chromatograph gas pipeline 36, etc.

[0038] In the technical solution of the utility model, the liquid nitrogen in the liquid nitrogen storage tank 1 is pressurized by the booster valve 2 and then enters the vaporizer 3 to become nitrogen, then is heated by the heater 4, and finally enters the buffer tank 5. The outlet pressure is adjusted by the self-operated pressure reducing valve 6 to make it slightly lower than the pressure of the instrument gas provided by the molecular sieve 51. In this way, when the molecular sieve 51 can normally supply the instrument gas, the nitrogen of the backup nitrogen system 100 is not sent out and is in a standby state. When the instrument gas provided by the molecular sieve 51 fluctuates, the backup nitrogen system 100 can play a stabilizing role in time to ensure that the air separation unit can operate normally. Among them, the pipeline between the liquid nitrogen storage tank 1 and the vaporizer 3 is provided with a tank outlet valve for controlling the circulation of liquid nitrogen.

[0039] In an air separation unit, heating gas is also indispensable. Before starting up, the low-temperature molecular sieve 51, distillation tower, circulating liquid oxygen pump and other equipment in the air separation unit must be fed with heating gas with a qualified dew point to heat the equipment and drive out the moist air, aluminum chips and other fine impurities in the equipment to keep the equipment dry and clean and prevent the water molecules in the moist air from freezing in the pipeline. The car charging pump equipment also needs to be operated after the air separation unit is stopped. At this time, the introduction of heating gas can also prevent the car charging pump from freezing, providing an important guarantee for the safe operation of the equipment. The heating gas also passes through the molecular sieve 51. When the air separation unit is unexpectedly shut down, the molecular sieve 51 no longer provides heating gas, which will cause pollution or damage to the various equipment in the air separation unit. For this reason, in one embodiment of the utility model, please refer to Figure 1 and Figure 3 The backup nitrogen system 100 also includes a heating gas main pipeline 8 and a first pipeline jumper assembly. The heating gas main pipeline 8 is used to communicate with the heating gas outlet of the molecular sieve 51 of the air separation unit. The first pipeline jumper assembly includes a first pipeline jumper tube and a first pipeline jumper valve 9. The first pipeline jumper tube is used to connect the instrument gas main pipeline 7 and the heating gas main pipeline 8. The first pipeline jumper valve 9 is arranged on the first pipeline jumper tube. In this way, when the air separation unit is unexpectedly shut down, the first pipeline jumper valve 9 can be opened, and the nitrogen provided by the backup nitrogen system 100 can enter the heating gas main pipeline 8 through the instrument gas main pipeline 7 to provide heating gas for various equipment of the air separation unit. Among them, the heating gas main pipeline 8 is connected with the pipelines of various equipment of the air separation unit, including the heating gas pipeline of the circulating oxygen pump A, the heating gas pipeline of the circulating oxygen pump B, the heating gas pipeline of the low-temperature expander 4039, the heating gas pipeline of the low-temperature expander 4039, the heating gas pipeline of the argon system 41, the heating gas pipeline of the liquid argon tank area 42, the heating gas pipeline of the liquid nitrogen tank area 43, the heating gas pipeline of the liquid oxygen tank area 44, etc.

[0040] In the air separation unit, sealing gas is also very important. The sealing gas is provided by the molecular sieve 51 through the pipeline. However, during the startup of the air separation unit, the sealing gas provided by the molecular sieve 51 may have insufficient pressure, which may lead to problems such as poor sealing and leakage of cryogenic liquid. For this reason, in one embodiment of the utility model, please refer to Figure 1 The backup nitrogen system 100 also includes a second pipeline jumper assembly, which includes a second pipeline jumper tube and a second pipeline jumper valve 10. The second pipeline jumper valve 10 is arranged on the second pipeline jumper tube. One end of the second pipeline jumper tube is connected to the heating gas main pipeline 8, and the other end of the second pipeline jumper tube is used to connect the liquid oxygen pump sealing gas pipeline 11 and the expander sealing gas pipeline 12 of the air separation unit. During the startup of the air separation unit, by opening the first pipeline jumper valve 9 and the second pipeline jumper valve 10, the nitrogen discharged from the buffer tank 5 can flow from the instrument gas main pipeline 7 to the heating gas main pipeline 8, and then flow to the liquid oxygen pump sealing gas pipeline 11 and the expander sealing gas pipeline 12, so as to provide stable sealing gas for the liquid oxygen pump and the expander of the air separation unit, ensure the normal operation of the expander, and the good sealing performance of the liquid oxygen pump.

[0041] During the normal operation of the air separation unit, the dirty nitrogen gas is used to provide protective gas for each device of the air separation unit through the protective gas main pipeline 14, so as to reduce the use cost. However, when the air separation unit stops unexpectedly, the supply of dirty nitrogen gas will be stopped. For this reason, in one embodiment of the utility model, please refer to Figure 1 and Figure 3 The backup nitrogen system 100 also includes a third pipeline jumper assembly, which includes a third pipeline jumper tube and a third pipeline jumper valve 13. The third pipeline jumper valve 13 is arranged on the third pipeline jumper tube. One end of the third pipeline jumper tube is connected to the heating gas main pipeline 8, and the other end of the third pipeline jumper tube is used to connect the protection gas main pipeline 14 of the air separation unit. In this way, when the air separation unit is unexpectedly shut down, by opening the first pipeline jumper valve 9 and the third pipeline jumper valve 13, the backup nitrogen system 100 can provide nitrogen as a protection gas to the protection gas main pipeline 14 through the instrument gas main pipeline 7 and the heating gas main pipeline 8, so as to ensure the safety of the air separation unit. Among them, the protection gas main pipeline 14 is connected to the circulating oxygen pump interlayer protection gas pipeline 45, the cold box interlayer protection gas pipeline 46, the expander cold box interlayer gas protection pipeline 47, the oxygen tank protection gas pipeline 48, the nitrogen tank protection gas pipeline 49 and the argon tank protection gas pipeline 50.

[0042] It is understandable that some air compressors and boosters are integrated structures. In this case, the booster will rotate with the air compressor. During the rotation, the heated gas provided by the molecular sieve 51 will maintain the positive pressure at the booster inlet. However, when the air separation unit is started, please refer to Figure 1The pressure of the heated gas provided by the molecular sieve 51 will fluctuate. Taking this into consideration, in one embodiment of the utility model, the backup nitrogen system 100 also includes a bypass manual valve 15. The bypass manual valve 15 is arranged at one end of the heated gas main pipeline 8 close to the molecular sieve 51 of the air separation unit. When the air separation unit is started, the first pipeline jumper valve 9 and the bypass manual valve 15 can be opened. At this time, the backup nitrogen system 100 replenishes air to the booster inlet to avoid the booster vacuum accident. It can also avoid excessive fluctuations in the airflow passing through the molecular sieve 51, which may cause the molecular sieve 51 to carry water.

[0043] Further, in an embodiment of the present utility model, please refer to Figure 1 The backup nitrogen system 100 also includes a turbine isolation gas pipeline 16, which is connected to the instrument gas main pipeline 7. When the air separation unit is unexpectedly shut down, the nitrogen provided by the backup nitrogen system 100 can enter the turbine isolation gas pipeline 16 through the instrument gas main pipeline 7 to ensure the safe shutdown of the turbine.

[0044] Furthermore, in an embodiment of the present invention, please refer to Figure 1 The backup nitrogen system 100 also includes a booster sealed gas pipeline 17, which is connected to the instrument gas main pipeline 7. When the air separation unit is unexpectedly shut down, the nitrogen provided by the backup nitrogen system 100 can enter the booster sealed gas pipeline 17 through the instrument gas main pipeline 7 to ensure the safe shutdown of the booster.

[0045] Specifically, in one embodiment of the present invention, please refer to Figure 1 The backup nitrogen system 100 further includes a first safety valve 18, which is disposed on the pipeline between the liquid nitrogen storage tank 1 and the vaporizer 3; the backup nitrogen system 100 further includes a first discharge valve 19, which is disposed on the pipeline between the liquid nitrogen storage tank 1 and the vaporizer 3. The first safety valve 18 and the first discharge valve 19 can protect the pipeline, thereby improving the safety of the backup nitrogen system 100 during use.

[0046] Further, in an embodiment of the present utility model, please refer to Figure 1 The backup nitrogen system 100 further includes a second safety valve 20, which is disposed on the pipeline between the heater 4 and the buffer tank 5; the backup nitrogen system 100 further includes a second discharge valve 21, which is disposed on the pipeline between the heater 4 and the buffer tank 5. The second safety valve 20 and the second discharge valve 21 can protect the pipeline, thereby improving the safety of the backup nitrogen system 100 during use.

[0047] Furthermore, in one embodiment of the present invention, the vaporizer 3 is an air bath vaporizer 3, and in other embodiments of the present invention, the vaporizer 3 may be a steam heating vaporizer 3, a hot water bath vaporizer 3, a forced ventilation vaporizer 3, an electric heating vaporizer 3, or a solid heat conduction vaporizer 3, etc.

[0048] Specifically, in one embodiment of the present invention, please refer to Figure 1 The backup nitrogen system 100 also includes a remote pressure gauge 22, which is arranged on the instrument gas main pipeline 7. The remote pressure gauge 22 can detect the pressure of the instrument gas main pipeline 7 and transmit corresponding information, so as to find problems in time.

[0049] The utility model further provides an instrument gas system for an air separation unit, which includes the backup nitrogen system 100. The specific structure of the backup nitrogen system 100 refers to the above-mentioned embodiment. Since the instrument gas system for an air separation unit adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0050] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A backup nitrogen system for an air separation unit, characterized in that: include: A liquid nitrogen storage tank, wherein a booster valve is provided at the output end of the liquid nitrogen storage tank; A vaporizer, wherein an input end of the vaporizer is connected to an output end of the liquid nitrogen storage tank through a pipeline; a heater, wherein an input end of the heater is connected to an output end of the gasifier through a pipeline; A buffer tank, wherein an input end of the buffer tank is connected to an output end of the heater through a pipeline; A self-operated pressure reducing valve, which is arranged at the input end of the buffer tank; as well as An instrument gas main pipeline is used to communicate with the instrument gas outlet of the molecular sieve of the air separation device, and the output end of the buffer tank is connected to the instrument gas main pipeline.

2. The nitrogen backup system according to claim 1, characterized in that: The backup nitrogen system also includes a heating gas main pipeline and a first pipeline jumper assembly; The heating gas main pipeline is used to communicate with the heating gas outlet of the molecular sieve of the air separation device; The first pipeline jumper assembly includes a first pipeline jumper tube and a first pipeline jumper valve. The first pipeline jumper tube is used to connect the instrument gas main pipeline and the heating gas main pipeline. The first pipeline jumper valve is arranged on the first pipeline jumper tube.

3. The nitrogen backup system according to claim 2, characterized in that: The backup nitrogen system also includes a second pipeline jumper assembly, which includes a second pipeline jumper tube and a second pipeline jumper valve. The second pipeline jumper valve is arranged on the second pipeline jumper tube. One end of the second pipeline jumper tube is connected to the heating gas main pipeline, and the other end of the second pipeline jumper tube is used to connect the liquid oxygen pump sealing gas pipeline and the expander sealing gas pipeline of the air separation unit.

4. The nitrogen backup system according to claim 2, characterized in that: The backup nitrogen system also includes a third pipeline jumper assembly, which includes a third pipeline jumper tube and a third pipeline jumper valve. The third pipeline jumper valve is arranged on the third pipeline jumper tube. One end of the third pipeline jumper tube is connected to the heating gas main pipeline, and the other end of the third pipeline jumper tube is used to connect to the protection gas main pipeline of the air separation device.

5. The nitrogen backup system according to claim 2, characterized in that: The backup nitrogen system also includes a bypass hand valve, which is arranged at one end of the heating gas main pipeline close to the molecular sieve of the air separation device.

6. The nitrogen backup system according to any one of claims 1 to 5, characterized in that: The backup nitrogen system also includes a steam turbine isolation gas pipeline, and the steam turbine isolation gas pipeline is connected to the instrument gas main pipeline.

7. The nitrogen backup system according to any one of claims 1 to 5, characterized in that: The backup nitrogen system also includes a supercharger sealed air pipeline, and the supercharger sealed air pipeline is connected to the instrument gas main pipeline.

8. The nitrogen backup system according to any one of claims 1 to 5, characterized in that: The backup nitrogen system further comprises a first safety valve, which is arranged on a pipeline between the liquid nitrogen storage tank and the vaporizer; and / or The backup nitrogen system further includes a first discharge valve, which is arranged on a pipeline between the liquid nitrogen storage tank and the vaporizer.

9. The nitrogen backup system according to any one of claims 1 to 5, characterized in that: The backup nitrogen system further comprises a second safety valve, which is arranged on a pipeline between the heater and the buffer tank; and / or The backup nitrogen system further includes a second discharge valve, which is disposed on a pipeline between the heater and the buffer tank.

10. An instrument gas system for an air separation unit, characterized in that: The air separation unit instrument gas system comprises a backup nitrogen system as claimed in any one of claims 1 to 9.

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