Method and system for recovering and reusing nitrogen

Abstract

The present application relates to air separation and rare gas extraction technical field, disclose a kind of nitrogen recycling method and system, including low-pressure nitrogen pipe network, first air temperature type heat exchanger, second air temperature type heat exchanger, self-regulating valve and pressure regulating valve. By the low-pressure nitrogen gas generated by oxygen removal tower condenser and the heat exchange nitrogen gas discharged from evaporator are respectively re-heated by air temperature type heat exchanger after heat exchange and are merged into low-pressure nitrogen pipe network, mixed nitrogen gas is supplied to molecular sieve adsorber as regeneration purge gas source, and is switched to liquid oxygen adsorber during non-regeneration period of molecular sieve;While using self-regulating valve to introduce external nitrogen to supplement when pipe network pressure is insufficient, using pressure regulating valve to release excess nitrogen when pipe network pressure is too high, to realize the automatic stable control of pipe network pressure. The waste nitrogen originally vented is effectively recycled, instead of external network high-purity nitrogen supply, reduces equipment load and production cost, realizes energy saving and consumption reduction.

Description

Technical Field

[0001] This invention relates to the field of air separation and rare gas extraction technology, and in particular to a method and system for nitrogen recovery and reuse. Background Technology

[0002] In the field of rare gas extraction, krypton-xenon mixtures are typically extracted from air separation units using cryogenic distillation, and then further purified in a krypton-xenon refining system. Existing krypton-xenon refining systems generally include a deoxygenation tower (distillation tower) and a molecular sieve adsorption system. The deoxygenation tower is used to concentrate the crude krypton-xenon mixture via cryogenic distillation; it has a condenser at the top and an evaporator at the bottom. The molecular sieve adsorption system removes moisture and carbon dioxide from the gas during the krypton-xenon refining process; its molecular sieve adsorbers require periodic regeneration.

[0003] In existing processes, liquid nitrogen in the condenser at the top of the deaerator tower evaporates through heat exchange, generating a low-pressure nitrogen gas with a flow rate of approximately 200 m³ / h. This nitrogen gas, due to its low pressure, cannot be directly recovered and reused within the system and is typically released into the atmosphere, resulting in a double waste of cooling capacity and gas. Simultaneously, the evaporator at the bottom of the deaerator tower requires an internal nitrogen gas source at a pressure of 5 bar and a flow rate of approximately 100 m³ / h for heat exchange with the liquid in the tower bottom. After heat exchange, this nitrogen gas becomes low-temperature, high-pressure nitrogen and is also directly vented. Furthermore, the regeneration of the molecular sieve adsorber in the krypton-xenon refining process requires a large amount of high-temperature nitrogen for purging, typically at a flow rate of approximately 300 m³ / h. Currently, the industry generally uses high-purity nitrogen supplied from external pipelines as the regeneration source. This not only increases the operating load of the nitrogen generation equipment but also significantly increases the production costs for enterprises.

[0004] Therefore, existing technologies suffer from at least the following drawbacks: the low-pressure evaporated gas generated by the deaerator condenser in the distillation system and the nitrogen discharged after heat exchange from the distillation evaporator are not effectively recovered and utilized, resulting in significant energy waste; while the nitrogen required for molecular sieve regeneration relies entirely on external grid supply, leading to high operating costs. To date, no systematic solution has emerged in the industry capable of recovering these two streams of waste nitrogen and adapting them to the needs of molecular sieve regeneration. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for nitrogen recovery and reuse, which solves the problems of resource waste caused by the direct venting of nitrogen after heat exchange between the low-pressure evaporator gas and the evaporator in the deaerator condenser of the krypton-xenon refining system, and the high operating cost caused by the reliance on high-purity nitrogen from the external network for molecular sieve regeneration.

[0006] To achieve the above objectives, the present invention provides a nitrogen recovery and reuse system applied to a krypton-xenon refining system. The krypton-xenon refining system includes a deoxygenation tower and a molecular sieve adsorber. A condenser is installed at the top of the deoxygenation tower, and an evaporator is installed at the bottom of the deoxygenation tower.

[0007] Low-pressure nitrogen pipeline network;

[0008] The first ambient air heat exchanger has its inlet connected to the nitrogen outlet of the condenser and its outlet connected to the low-pressure nitrogen pipeline.

[0009] The second ambient air heat exchanger has its inlet connected to the nitrogen outlet of the evaporator and its outlet connected to the low-pressure nitrogen pipeline.

[0010] A self-regulating valve, one end of which is connected to the low-pressure nitrogen pipeline network;

[0011] A pressure regulating valve, one end of which is connected to the low-pressure nitrogen pipeline network;

[0012] The outlet of the low-pressure nitrogen pipeline is connected to the inlet of the molecular sieve adsorber.

[0013] A condenser pressure regulating valve is installed on the pipeline between the air inlet of the first ambient temperature heat exchanger and the nitrogen outlet of the condenser.

[0014] A flow regulating valve and an electric heater are sequentially connected on the pipeline between the outlet of the low-pressure nitrogen pipeline and the inlet of the molecular sieve adsorber. The inlet of the flow regulating valve is connected to the outlet of the low-pressure nitrogen pipeline, the outlet of the flow regulating valve is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the inlet of the molecular sieve adsorber.

[0015] The outlet of the low-pressure nitrogen pipeline is also connected to the inlet of the liquid oxygen adsorber.

[0016] The low-pressure nitrogen pipeline network uses DN80 stainless steel pipes.

[0017] A method for recovering and reusing nitrogen includes the following steps:

[0018] The low-pressure nitrogen gas discharged from the nitrogen outlet of the condenser is reheated by the first ambient temperature heat exchanger and then sent into the low-pressure nitrogen pipeline network. The nitrogen gas discharged from the nitrogen outlet of the evaporator after heat exchange is reheated by the second ambient temperature heat exchanger and then sent into the low-pressure nitrogen pipeline network.

[0019] The mixed nitrogen gas in the low-pressure nitrogen pipeline is delivered to the molecular sieve adsorber through the outlet of the low-pressure nitrogen pipeline.

[0020] External nitrogen is introduced into the low-pressure nitrogen pipeline through the self-regulating valve, and excess nitrogen in the low-pressure nitrogen pipeline is discharged to the vent pipe through the pressure regulating valve.

[0021] Specifically, the process of conveying the mixed nitrogen gas in the low-pressure nitrogen pipeline network to the molecular sieve adsorber via the outlet of the low-pressure nitrogen pipeline network includes:

[0022] When the molecular sieve adsorber is in a non-regeneration period, the mixed nitrogen in the low-pressure nitrogen pipeline is switched and transported to the liquid oxygen adsorber.

[0023] Specifically, the process includes: introducing external nitrogen gas into the low-pressure nitrogen pipeline network through the self-regulating valve; and discharging excess nitrogen gas from the low-pressure nitrogen pipeline network into the vent pipe through the pressure regulating valve.

[0024] When the pressure of the low-pressure nitrogen pipeline is lower than the first preset value, the self-regulating valve is opened; when the pressure of the low-pressure nitrogen pipeline is higher than the second preset value, the pressure regulating valve is opened.

[0025] The first preset value is 20 kPa, and the second preset value is 70 kPa.

[0026] When the pressure of the low-pressure nitrogen pipeline is between 30 kPa and 50 kPa, both the self-regulating valve and the pressure regulating valve remain closed.

[0027] This invention discloses a method and system for nitrogen recovery and reuse. By constructing an independent low-pressure nitrogen pipeline network, low-pressure nitrogen generated by the deaerator condenser in the krypton-xenon refining system and nitrogen discharged from the bottom evaporator after heat exchange are respectively reheated to room temperature via an ambient temperature heat exchanger and then fed into the low-pressure nitrogen pipeline network. The mixed nitrogen is preferentially supplied to the molecular sieve adsorber as a regeneration purge gas source using this network. During the non-regeneration period of the molecular sieve adsorber, surplus nitrogen is switched to the liquid oxygen adsorber as a regeneration gas source. Simultaneously, a self-regulating valve is installed on the low-pressure nitrogen pipeline network to introduce external nitrogen for supplementation when the network pressure is insufficient, and a pressure regulating valve is installed to release excess nitrogen to the vent pipe when the network pressure is too high, thereby maintaining the network pressure within a preset range for stable operation. Therefore, this invention effectively recovers and utilizes the two streams of waste nitrogen gas that were originally directly vented from the deaerator condenser and evaporator, allowing them to replace the high-purity nitrogen gas from the external network to meet the regeneration needs of molecular sieves. While realizing the resource recycling of waste nitrogen gas, it significantly reduces the load on nitrogen production equipment and the production cost of enterprises, achieving the dual benefits of energy saving, consumption reduction and economic efficiency improvement. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0029] Figure 1 This is a schematic diagram of the nitrogen recovery and reuse system according to the first embodiment of the present invention.

[0030] Figure 2 This is a flowchart of the nitrogen recovery and reuse method according to the second embodiment of the present invention.

[0031] In the diagram: V1 - manual nitrogen shut-off valve, V2 - flow regulating valve, V3 - condenser pressure regulating valve, V4 - liquid nitrogen inlet valve, V5 - heated nitrogen control valve, LI - regenerated nitrogen flow meter, V6 - pressure regulating valve, V7 - self-regulating regulating valve, E1 - first ambient air heat exchanger, E2 - second ambient air heat exchanger, PT - pressure measuring point, TI - temperature measuring point, 100 - low-pressure nitrogen pipeline. Detailed Implementation

[0032] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0033] First embodiment:

[0034] Please refer to Figure 1 This invention provides a nitrogen recovery and reuse system applied to a krypton-xenon refining system. The krypton-xenon refining system includes a deoxygenation tower and a molecular sieve adsorber. A condenser is installed at the top of the deoxygenation tower, and an evaporator is installed at the bottom of the deoxygenation tower. The system includes a low-pressure nitrogen pipeline network 100, a first ambient air heat exchanger E1, a second ambient air heat exchanger E2, a self-regulating valve V7, a pressure regulating valve V6, a condenser pressure regulating valve V3, a flow regulating valve V2, and an electric heater.

[0035] The low-pressure nitrogen pipeline 100 uses DN80 stainless steel pipe, which is a 304 stainless steel pipe with a diameter of Φ89×4. The low-pressure nitrogen pipeline 100 is connected to the nitrogen outlet of the condenser and the nitrogen outlet of the evaporator respectively, and is used to collect the two waste nitrogen streams and balance the pressure of the two recovered nitrogen streams.

[0036] The inlet of the first ambient air heat exchanger E1 is connected to the nitrogen outlet of the condenser, and the outlet of the first ambient air heat exchanger E1 is connected to the low-pressure nitrogen pipeline 100. The rated capacity of the first ambient air heat exchanger E1 is 200 Nm³ / h, and it is used to reheat the low-pressure nitrogen generated by the condenser to room temperature before introducing it into the low-pressure nitrogen pipeline 100.

[0037] The inlet of the second ambient air heat exchanger E2 is connected to the nitrogen outlet of the evaporator, and the outlet of the second ambient air heat exchanger E2 is connected to the low-pressure nitrogen pipeline 100. The rated capacity of the second ambient air heat exchanger E2 is 100 Nm³ / h, and it is used to reheat the nitrogen discharged from the evaporator after heat exchange to room temperature before introducing it into the low-pressure nitrogen pipeline 100.

[0038] A condenser pressure regulating valve V3 is installed on the pipeline between the air inlet of the first ambient air heat exchanger E1 and the nitrogen outlet of the condenser to regulate the nitrogen outlet pressure of the condenser. A corresponding control valve can be installed on the pipeline between the air inlet of the second ambient air heat exchanger E2 and the nitrogen outlet of the evaporator.

[0039] One end of the self-regulating valve V7 is connected to the low-pressure nitrogen pipeline 100, and the other end serves as a gas replenishment interface connected to an external nitrogen source. The set opening pressure of the self-regulating valve V7 is 20 kPa. When the pressure of the low-pressure nitrogen pipeline 100 is lower than 20 kPa, the self-regulating valve V7 automatically opens, introducing external nitrogen into the low-pressure nitrogen pipeline 100 to replenish its pressure. When the pressure of the low-pressure nitrogen pipeline 100 recovers, the self-regulating valve V7 automatically closes or shuts off.

[0040] One end of the pressure regulating valve V6 is connected to the low-pressure nitrogen pipeline 100, and the other end of the pressure regulating valve V6 serves as an exhaust port connected to the vent pipe. The set opening pressure of the pressure regulating valve V6 is 70 kPa. When the pressure in the low-pressure nitrogen pipeline 100 exceeds 70 kPa, the pressure regulating valve V6 automatically opens, releasing excess nitrogen from the low-pressure nitrogen pipeline 100 into the vent pipe. The pressure regulating valve V6 is adjusted by the control system based on feedback signals from the pressure measuring point PT.

[0041] The outlet of the low-pressure nitrogen pipeline 100 is connected to the inlet of the molecular sieve adsorber. Specifically, a flow regulating valve V2 and an electric heater are sequentially connected on the pipeline between the outlet of the low-pressure nitrogen pipeline 100 and the inlet of the molecular sieve adsorber. The inlet of the flow regulating valve V2 is connected to the outlet of the low-pressure nitrogen pipeline 100, the outlet of the flow regulating valve V2 is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the inlet of the molecular sieve adsorber. The flow regulating valve V2 is used to regulate the flow rate of regenerated nitrogen entering the molecular sieve adsorber, and the electric heater is used to heat the nitrogen to the high temperature required for molecular sieve regeneration. The outlet of the low-pressure nitrogen pipeline 100 is also connected to the inlet of the liquid oxygen adsorber, used to switch surplus nitrogen to the liquid oxygen adsorber as a regeneration purge gas source during the non-regeneration period of the molecular sieve adsorber. In addition, the outlet of the low-pressure nitrogen pipeline 100 can also be connected to the heating gas path of the distillation column level gauge and the protection gas path of the cold box, respectively serving as the heating gas source for the level gauge and the sealing protection gas source for the cold box.

[0042] The working principle of this system is as follows:

[0043] During system operation, the deaerator tower operates normally. Liquid nitrogen in the condenser evaporates through heat exchange, generating low-pressure nitrogen gas with a flow rate of approximately 200 m³ / h. This low-pressure nitrogen gas passes through the condenser pressure regulating valve V3 and enters the first ambient air temperature heat exchanger E1. After being reheated to room temperature by E1, it is then fed into the low-pressure nitrogen network 100. Simultaneously, nitrogen gas at a pressure of 5 bar and a flow rate of approximately 100 m³ / h is introduced into the evaporator as an internal gas source to heat the liquid in the tower bottom. The low-temperature nitrogen gas, after heat exchange, is reheated to room temperature by the second ambient air temperature heat exchanger E2 before being fed into the low-pressure nitrogen network 100. The two nitrogen streams mix in the low-pressure nitrogen network 100.

[0044] When the molecular sieve adsorber needs regeneration, the mixed nitrogen in the low-pressure nitrogen network 100 is preferentially delivered to the molecular sieve adsorber via the flow regulating valve V2 and the electric heater, serving as the purge gas source for molecular sieve regeneration. When the molecular sieve adsorber is not in the regeneration period or when the system has a gas production surplus, the mixed nitrogen in the low-pressure nitrogen network 100 is switched to the liquid oxygen adsorber as the regeneration purge gas source, or delivered to the heating gas path of the distillation column level gauge as the heating gas source, or delivered to the cold box as the sealing protection gas source.

[0045] During system operation, the self-regulating valve V7 monitors the pressure of the low-pressure nitrogen pipeline 100 in real time. When the pipeline pressure drops below 20 kPa, the self-regulating valve V7 automatically opens to introduce external nitrogen for replenishment, ensuring uninterrupted pressure and flow of the end-regeneration gas source. Once the pipeline pressure recovers, the self-regulating valve V7 automatically closes until it shuts off completely. The pressure regulating valve V6 monitors the pipeline pressure in real time via the pressure measuring point PT. When the pipeline pressure exceeds 70 kPa, the pressure regulating valve V6 automatically opens to release excess nitrogen into the vent pipe, stabilizing the pipeline pressure at 70 kPa. When the pipeline pressure is between 30 kPa and 50 kPa, both the self-regulating valve V7 and the pressure regulating valve V6 remain closed, allowing the pipeline pressure to naturally balance, and the system can meet regeneration requirements without external gas replenishment.

[0046] The following section provides a detailed description of the system's operating status under three typical conditions:

[0047] Operating Condition 1: Individual Molecular Sieve Regeneration

[0048] Close the manual nitrogen shut-off valve V1 connected to the industrial pipeline, disconnecting the original connection to the industrial pipeline. The deaerator condenser and evaporator are in normal operating condition. The low-pressure nitrogen produced by the condenser is reheated by the first ambient air heat exchanger E1 before entering the low-pressure nitrogen pipeline 100. The nitrogen discharged from the evaporator after heat exchange is reheated by the second ambient air heat exchanger E2 before entering the low-pressure nitrogen pipeline 100. At this time, the molecular sieve adsorber is in regeneration mode, with a gas consumption of approximately 300 Nm³ / h. The gas consumption of the pipeline is basically balanced with the gas production of the two waste nitrogen lines. The self-regulating valve V7 and the pressure regulating valve V6 are both closed, and the pipeline pressure is naturally maintained between 30 kPa and 50 kPa. The system can meet the regeneration requirements without external gas supply.

[0049] Operating Condition 2: Simultaneous regeneration of molecular sieve adsorber and liquid oxygen adsorber (peak gas consumption)

[0050] When the liquid oxygen adsorber is put into regeneration, the total gas demand briefly rises to approximately 400 Nm³ / h, exceeding the system's recovery limit. At this time, the pipeline pressure gradually decreases. When the pressure drops to 18 kPa, the spring mechanism of the self-regulating valve V7 is triggered, automatically opening to introduce external nitrogen for replenishment, ensuring uninterrupted pressure and flow of the end-stage regeneration gas source. After the liquid oxygen adsorber regeneration ends and the total gas demand recovers to approximately 300 Nm³ / h, the pipeline pressure rises again, and the self-regulating valve V7 automatically closes until it shuts off completely.

[0051] Operating Condition 3: No Regeneration Requirement (Off-Peak Gas Consumption)

[0052] When both the molecular sieve adsorber and the liquid oxygen adsorber are in adsorption mode, the recovered nitrogen has nowhere to be disposed of, and the pipeline pressure rises slowly. When the pressure rises to 75 kPa, the pressure measuring point PT feeds a signal to the control system, which then automatically opens the pressure regulating valve V6 to release excess nitrogen into the vent pipe, stabilizing the pipeline pressure at 70 kPa. After the gas-using equipment is put back into regeneration, the pipeline pressure drops, and the pressure regulating valve V6 automatically closes.

[0053] Second embodiment:

[0054] Please refer to Figure 2 This invention provides a method for nitrogen recovery and reuse, comprising the following steps:

[0055] S201: The low-pressure nitrogen gas discharged from the nitrogen outlet of the condenser is reheated by the first ambient temperature heat exchanger E1 and then sent to the low-pressure nitrogen pipeline 100; the nitrogen gas discharged from the nitrogen outlet of the evaporator after heat exchange is reheated by the second ambient temperature heat exchanger E2 and then sent to the low-pressure nitrogen pipeline 100.

[0056] Specifically, the liquid nitrogen in the deaerator condenser evaporates through heat exchange to generate low-pressure nitrogen gas with a flow rate of approximately 200 m³ / h. This low-pressure nitrogen gas is discharged from the nitrogen outlet of the condenser, and after its pressure is regulated by the condenser pressure regulating valve V3, it enters the first ambient air heat exchanger E1. The first ambient air heat exchanger E1 uses ambient air as a heat source to reheat the low-pressure nitrogen gas to room temperature. The reheated low-pressure nitrogen gas is then sent from the outlet of the first ambient air heat exchanger E1 into the low-pressure nitrogen pipeline 100.

[0057] Simultaneously, nitrogen gas at a pressure of 5 bar and a flow rate of approximately 100 m³ / h is introduced into the deaerator evaporator as an internal gas source to heat the liquid in the bottom of the tower. After heat exchange, the low-temperature nitrogen gas is discharged from the nitrogen outlet of the evaporator and enters the second ambient air heat exchanger E2. The second ambient air heat exchanger E2 uses ambient air as a heat source to reheat the nitrogen gas to room temperature. The reheated nitrogen gas is then sent from the outlet of the second ambient air heat exchanger E2 into the low-pressure nitrogen pipeline 100.

[0058] The two streams of nitrogen gas, reheated to room temperature, are mixed in the low-pressure nitrogen pipeline network 100 to form mixed nitrogen gas.

[0059] S202: The mixed nitrogen gas in the low-pressure nitrogen pipeline 100 is transported to the molecular sieve adsorber through the outlet of the low-pressure nitrogen pipeline 100;

[0060] Specifically, when the molecular sieve adsorber needs regeneration, the mixed nitrogen in the low-pressure nitrogen network 100 is preferentially used as the regeneration purge gas source. The mixed nitrogen in the low-pressure nitrogen network 100 flows out from the outlet of the low-pressure nitrogen network 100, and after the flow rate is regulated by the flow regulating valve V2, it enters the electric heater. The electric heater heats the mixed nitrogen to the high temperature required for molecular sieve regeneration, and the heated high-temperature nitrogen enters the molecular sieve adsorber from the outlet of the electric heater to purge and regenerate the molecular sieve adsorber.

[0061] When the molecular sieve adsorber is in a non-regeneration period, the mixed nitrogen in the low-pressure nitrogen pipeline 100 is switched to the liquid oxygen adsorber as a regeneration purging gas source. Alternatively, the mixed nitrogen in the low-pressure nitrogen pipeline 100 can be switched to the heating gas path of the distillation column level gauge as a heating gas source, or switched to the cold box as a sealing protection gas source. By switching between different gas-using devices, surplus nitrogen is fully utilized.

[0062] S203: External nitrogen gas is introduced into the low-pressure nitrogen pipeline network 100 through the self-regulating valve V7, and excess nitrogen gas in the low-pressure nitrogen pipeline network 100 is discharged to the vent pipe through the pressure regulating valve V6.

[0063] Specifically, the system monitors the pressure of the low-pressure nitrogen pipeline 100 in real time during operation. When the pressure of the low-pressure nitrogen pipeline 100 falls below a first preset value, the self-regulating valve V7 is opened to introduce external nitrogen into the low-pressure nitrogen pipeline 100 for pressure replenishment. The first preset value is 20 kPa. When the pipeline pressure drops to 18 kPa, the spring mechanism of the self-regulating valve V7 is triggered, and the self-regulating valve V7 automatically opens wider to introduce external nitrogen for replenishment, ensuring uninterrupted pressure and flow of the end regeneration gas source. After the pipeline pressure recovers, the self-regulating valve V7 automatically closes until it shuts off completely.

[0064] When the pressure of the low-pressure nitrogen pipeline 100 exceeds a second preset value, the pressure regulating valve V6 is opened to release excess nitrogen from the low-pressure nitrogen pipeline 100 into the vent pipe. The second preset value is 70 kPa. When the pipeline pressure rises to 75 kPa, the pressure measuring point PT sends a feedback signal to the control system, which then automatically opens the pressure regulating valve V6 to release excess nitrogen into the vent pipe, stabilizing the pipeline pressure at 70 kPa. After the pipeline pressure drops, the pressure regulating valve V6 automatically closes.

[0065] When the pressure of the low-pressure nitrogen pipeline 100 is between 30 kPa and 50 kPa, both the self-regulating valve V7 and the pressure regulating valve V6 remain closed. At this time, the system's gas production and consumption are basically balanced, and the pipeline pressure naturally remains stable, requiring neither gas replenishment nor venting.

[0066] Through the above steps, the full recovery of low-pressure evaporating gas from the deaerator condenser and nitrogen after heat exchange in the krypton-xenon refining system is achieved, and it is recycled as the regeneration purge gas source for the molecular sieve adsorber. At the same time, through the linkage control of the self-regulating valve V7 and the pressure regulating valve V6, the automatic dynamic balance of the 100 pressure in the low-pressure nitrogen pipeline network is achieved.

[0067] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A nitrogen recovery and reuse system applied to a krypton-xenon refining system, the krypton-xenon refining system comprising a deoxygenation tower and a molecular sieve adsorber, wherein a condenser is provided at the top of the deoxygenation tower and an evaporator is provided at the bottom of the deoxygenation tower, characterized in that, include: Low-pressure nitrogen pipeline network; The first ambient air heat exchanger has its inlet connected to the nitrogen outlet of the condenser and its outlet connected to the low-pressure nitrogen pipeline. The second ambient air heat exchanger has its inlet connected to the nitrogen outlet of the evaporator and its outlet connected to the low-pressure nitrogen pipeline. A self-regulating valve, one end of which is connected to the low-pressure nitrogen pipeline network; A pressure regulating valve, one end of which is connected to the low-pressure nitrogen pipeline network; The outlet of the low-pressure nitrogen pipeline is connected to the inlet of the molecular sieve adsorber.

2. The nitrogen recovery and reuse system as described in claim 1, characterized in that, A condenser pressure regulating valve is installed on the pipeline between the air inlet of the first ambient temperature heat exchanger and the nitrogen outlet of the condenser.

3. The nitrogen recovery and reuse system as described in claim 1, characterized in that, A flow regulating valve and an electric heater are sequentially connected on the pipeline between the outlet of the low-pressure nitrogen pipeline and the inlet of the molecular sieve adsorber. The inlet of the flow regulating valve is connected to the outlet of the low-pressure nitrogen pipeline, the outlet of the flow regulating valve is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the inlet of the molecular sieve adsorber.

4. The nitrogen recovery and reuse system as described in claim 1, characterized in that, The outlet of the low-pressure nitrogen pipeline is also connected to the inlet of the liquid oxygen adsorber.

5. The nitrogen recovery and reuse system as described in claim 1, characterized in that, The low-pressure nitrogen pipeline network uses DN80 stainless steel pipes.

6. A method for nitrogen recovery and reuse, applied to a nitrogen recovery and reuse system as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The low-pressure nitrogen gas discharged from the nitrogen outlet of the condenser is reheated by the first ambient temperature heat exchanger and then sent into the low-pressure nitrogen pipeline network. The nitrogen gas discharged from the nitrogen outlet of the evaporator after heat exchange is reheated by the second ambient temperature heat exchanger and then sent into the low-pressure nitrogen pipeline network. The mixed nitrogen gas in the low-pressure nitrogen pipeline is delivered to the molecular sieve adsorber through the outlet of the low-pressure nitrogen pipeline. External nitrogen is introduced into the low-pressure nitrogen pipeline through the self-regulating valve, and excess nitrogen in the low-pressure nitrogen pipeline is discharged to the vent pipe through the pressure regulating valve.

7. The method for nitrogen recovery and reuse as described in claim 6, characterized in that, The mixed nitrogen gas in the low-pressure nitrogen pipeline is transported to the molecular sieve adsorber through the outlet of the low-pressure nitrogen pipeline, specifically including: When the molecular sieve adsorber is in a non-regeneration period, the mixed nitrogen in the low-pressure nitrogen pipeline is switched and transported to the liquid oxygen adsorber.

8. The method for nitrogen recovery and reuse as described in claim 6, characterized in that, External nitrogen is introduced into the low-pressure nitrogen pipeline network through the self-regulating valve, and excess nitrogen in the low-pressure nitrogen pipeline network is discharged into the vent pipe through the pressure regulating valve. Specifically, this includes: When the pressure of the low-pressure nitrogen pipeline is lower than the first preset value, the self-regulating valve is opened; when the pressure of the low-pressure nitrogen pipeline is higher than the second preset value, the pressure regulating valve is opened.

9. The method for nitrogen recovery and reuse as described in claim 8, characterized in that, The first preset value is 20 kPa, and the second preset value is 70 kPa.

10. The method for nitrogen recovery and reuse as described in claim 8, characterized in that, When the pressure of the low-pressure nitrogen pipeline is between 30 kPa and 50 kPa, both the self-regulating valve and the pressure regulating valve remain closed.

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