Nitrogen replacement system gas recycling and recycling device

Abstract

The application relates to the technical field of ethylene oxide sterilization auxiliary equipment, in particular to a nitrogen replacement system gas recycling and recycling device, which comprises a sterilization cabinet, a gas collecting unit, a buffer pressure stabilizing unit, a gas separating unit, a nitrogen purifying unit and a nitrogen storage unit; the gas collecting unit comprises a gas collecting pipe, and an input end of the gas collecting pipe is fixedly connected with an exhaust pipe end port of the sterilization cabinet. The device adopts a two-stage coupling separation process of a multistage polyimide hollow fiber membrane rough separation and a double-carbon molecular sieve pressure swing adsorption deep purification, a membrane assembly separates most of the oxygen to obtain 90%-95% rich nitrogen gas, double-tower PSA (pressure swing adsorption) alternately adsorbs and removes residual oxygen, high-purity nitrogen gas is finally output and recycled, the overall nitrogen recovery rate of the whole system is greatly improved, the fresh nitrogen consumption under the sterilization condition is reduced, after most of the nitrogen is recycled, the total amount of waste gas sent into a rear-end tail gas treatment system is reduced, tail gas reagents and energy consumption are reduced.

Description

Technical Field

[0001] This application relates to the field of ethylene oxide sterilization auxiliary equipment technology, and in particular to a nitrogen replacement system gas recovery and recycling device. Background Technology

[0002] Before sterilization, ethylene oxide sterilizers require nitrogen purging to remove oxygen, reducing the oxygen content inside the cabinet to below 1% to ensure sterilization effectiveness and safety. Nitrogen purging typically involves multiple cycles of vacuuming and nitrogen filling. After each purging, the discharged gas (containing nitrogen, residual oxygen, and trace amounts of EtO) is directly released into the atmosphere or into the exhaust gas treatment system.

[0003] Currently, existing nitrogen replacement systems do not address the recovery and reuse of emitted gases during the actual replacement process, thus the following problems remain:

[0004] (1) High nitrogen consumption. Each replacement requires a large amount of high-purity nitrogen, resulting in high operating costs.

[0005] (2) Waste of emitted gas. The emitted gas after replacement still contains 70% to 90% nitrogen, and direct emission results in waste of resources.

[0006] (3) High exhaust gas treatment load. The exhaust gas containing trace amounts of EtO increases the load on the exhaust gas treatment system.

[0007] Therefore, there is an urgent need for a nitrogen replacement system gas recovery and recycling device that can recover and recycle nitrogen from exhaust gases. Summary of the Invention

[0008] The purpose of this application is to solve at least one technical problem raised in the background art.

[0009] This application provides a nitrogen replacement system gas recovery and recycling device, including a sterilization cabinet, a gas collection unit, a buffer and pressure stabilization unit, a gas separation unit, a nitrogen purification unit, and a nitrogen storage unit;

[0010] The gas collection unit includes a gas collection pipe, the input end of which is fixedly connected to the external exhaust pipe port of the sterilizer;

[0011] The buffer and voltage stabilizing unit includes a gas buffer tank, the input end of which is fixedly connected to the output end of the gas collection pipe;

[0012] The gas separation unit includes a membrane separation module box and a vacuum pump. The vacuum pump is fixedly installed on the permeate side of the membrane separation module box and is used to extract the permeate gas and maintain the pressure difference across the membrane.

[0013] The nitrogen purification unit includes two pressure swing adsorption towers and a switching valve group, which is used to control the alternating adsorption and regeneration of the two adsorption towers.

[0014] The nitrogen storage unit includes a nitrogen storage tank, a pressure reducing valve assembly, and a pressure gauge.

[0015] Preferably, the gas collection pipe is used to collect the exhaust gas from the sterilization cabinet, and an isolation valve and a check valve are fixedly installed on the surface of the gas collection pipe to prevent gas backflow.

[0016] Preferably, the volume of the gas buffer tank is 1.5 to 2 times the volume of the sterilizer, and the gas buffer tank is used to temporarily store the emitted gas and uniformly mix the gas components.

[0017] Preferably, a gas analyzer is fixedly mounted on the upper surface of the gas buffer tank, a gas detection tube is fixedly mounted on the input end of the gas analyzer, the end of the gas detection tube away from the gas analyzer extends to the output end of the gas buffer tank and is fixedly connected, and a gas delivery tube is fixedly mounted on the output end of the gas analyzer.

[0018] Preferably, the membrane separation component box is equipped with a multi-stage vacuum fiber membrane component, and the multi-stage vacuum fiber membrane component is made of polyimide. The multi-stage vacuum fiber membrane component utilizes the difference in the permeation rate of oxygen and nitrogen in the membrane to separate oxygen from the gas.

[0019] Preferably, a nitrogen-rich gas pipe is fixedly installed at the output end of the vacuum pump, and a diversion conduit is fixedly installed at the input end of the two pressure swing adsorption towers. The output end of the nitrogen-rich gas pipe is fixedly connected to the input end of the diversion conduit.

[0020] Preferably, the two pressure swing adsorption towers operate in an alternating mode. The interior of the pressure swing adsorption tower is filled with carbon molecular sieves. Utilizing the difference in adsorption capacity of carbon molecular sieves for oxygen and nitrogen, oxygen is adsorbed under high pressure and desorbed under low pressure. A T-shaped manifold is fixedly installed at the top output end of the pressure swing adsorption tower, and the output end of the T-shaped manifold is fixedly connected to the input end of the nitrogen storage tank.

[0021] Preferably, the switching valve assembly is fixedly installed on the surface of the T-shaped manifold, a recovery gas pipe is fixedly installed at the output end of the nitrogen storage tank, the output end of the recovery gas pipe extends into the interior of the sterilizer, the pressure reducing valve assembly is fixedly installed on the surface of the recovery gas pipe, the pressure reducing valve assembly is used to reduce the pressure of high-pressure nitrogen to the pressure required by the sterilizer, the pressure gauge is fixedly installed on the surface of the nitrogen storage tank, and a gas replenishment pipe is fixedly installed on the surface of the nitrogen storage tank, the input end of the gas replenishment pipe is connected to a liquid nitrogen storage tank or a high-purity nitrogen cylinder assembly, and is used to replenish fresh nitrogen. A gas replenishment regulating valve and a flow meter are installed on the surface of the gas replenishment pipe, the gas replenishment regulating valve is used to automatically replenish fresh nitrogen when the recovered nitrogen is insufficient, and the flow meter is used to measure the amount of nitrogen replenished.

[0022] Preferably, the surface of the gas separation unit is provided with a gas-liquid separation component, which includes a gas-liquid separation cylinder. The gas-liquid separation cylinder is fixedly installed on one side of the membrane separation component box, and a gas guide pipe is fixedly provided at the top output end of the gas-liquid separation cylinder. The end of the gas guide pipe away from the gas-liquid separation cylinder is fixedly connected to the input end of the vacuum pump. An inclined inlet pipe is fixedly provided at the input end of the gas-liquid separation cylinder. The end of the inclined inlet pipe away from the gas-liquid separation cylinder is fixedly connected to the output end of the membrane separation component box. A conical collection shell is threadedly connected to the bottom end of the gas-liquid separation cylinder. An annular rubber ring is fixedly provided on the inner wall of the gas-liquid separation cylinder. A filter screen is fixedly connected to the inner annular surface of the annular rubber ring. The filter screen is conical in shape, and a limiting sliding sleeve is fixedly embedded at the bottom end of the filter screen.

[0023] Preferably, a fixed crossbar is fixedly installed on the inner wall of the gas-liquid separator. An air guide impeller is rotatably installed at the center of the upper surface of the fixed crossbar. A rotating shaft is fixedly installed at the bottom end of the air guide impeller. The bottom end of the rotating shaft extends to the bottom of the impurity removal filter and is fixedly connected to a rotating plate. The rotating shaft is slidably connected to the inner wall of the limiting sleeve. Two arc-shaped top blocks are symmetrically fixed on the upper surface of the rotating plate. Two circular protrusions are fixedly installed at the bottom end of the impurity removal filter. The positions of the circular protrusions correspond to the arc-shaped top blocks. Movable frames are fixed at both ends of the rotating plate. A strip brush is fixed on the surface of the movable frame and overlaps with the surface of the impurity removal filter.

[0024] In summary, this application includes at least one of the following beneficial technical effects:

[0025] 1. This device adopts a two-stage coupled separation process of multi-stage polyimide hollow fiber membrane coarse separation and dual-carbon molecular sieve pressure swing adsorption deep purification. The membrane module first separates most of the oxygen to obtain 90% to 95% nitrogen-rich gas. The dual-tower PSA alternately adsorbs and removes the residual oxygen, finally producing high-purity nitrogen gas, which is then recycled. The overall nitrogen recovery rate of the entire system is greatly improved, the consumption of fresh nitrogen gas under sterilization conditions is reduced, and after recovering most of the nitrogen gas, the total amount of waste gas sent to the downstream tail gas treatment system is reduced, significantly reducing the long-term operating load of the tail gas treatment equipment and reducing the consumption of tail gas reagents and energy.

[0026] 2. The entire process features a closed-loop nitrogen circulation structure, equipped with automatic gas replenishment to ensure continuous sterilization production. The entire system forms a complete closed-loop recovery circuit. After the exhaust gas from the sterilizer is processed by the collection unit, buffer and pressure stabilization unit, and two-stage purification unit, the high-purity nitrogen is stored in the nitrogen storage tank. The pressure is then adjusted to 0.4-0.6 MPa by the pressure reducing valve group and sent back to the sterilizer for repeated nitrogen replacement and deoxygenation. The nitrogen storage tank is equipped with an independent gas replenishment unit, including a gas replenishment regulating valve and flow meter. When the recovered nitrogen output is insufficient or the gas volume in the tank is low, fresh nitrogen can be automatically replenished and the amount of nitrogen replenishment can be accurately measured. The dual adsorption towers adopt an alternating adsorption and regeneration working mode. One tower performs high-pressure adsorption to produce nitrogen, while the other tower performs low-pressure desorption to remove oxygen, ensuring a continuous and stable output of high-purity nitrogen. The gas supply will not be interrupted due to the regeneration process, ensuring continuous and uninterrupted production of the ethylene oxide sterilizer and avoiding the problems of single-tower PSA gas supply interruption and sterilization process shutdown.

[0027] 3. An independent gas-liquid separation unit is installed on the permeate side of the membrane separation module and at the front end of the vacuum pump inlet. The gas flow direction is from the permeate outlet of the membrane box to the inclined inlet pipe, which sends the gas into the gas-liquid separation cylinder. The top gas guide pipe connects to the vacuum pump input end, which is a pre-interception structure for the vacuum pump. After the mixed waste gas enters the cylinder, the conical impurity filter screen intercepts impurities, and the swirling air guide impeller accelerates the condensation of water vapor and trace amounts of liquid ethylene oxide. The liquid settles to the bottom conical collection shell by gravity and is collected in a concentrated manner, preventing the condensate from entering the vacuum pump and corroding the pump body or clogging the membrane fibers. The gas-liquid separation unit has a built-in rotating plate and strip brush linkage self-cleaning structure. The airflow drives the impeller to drive the brush body to continuously clean the filter screen, preventing the filter screen from being blocked by EtO condensate and dust, and maintaining the gas-liquid separation efficiency in the long term. It prevents the hollow fiber membrane from being soaked by the liquid accumulation in the membrane shell, stabilizes the oxygen-nitrogen separation coefficient, and significantly reduces the frequency of vacuum pump corrosion and failure maintenance, thereby reducing the maintenance cost of the entire set of equipment. Attached Figure Description

[0028] Figure 1 This is a front view structural diagram of this application;

[0029] Figure 2 This is a schematic diagram of the rear view structure of this application;

[0030] Figure 3 This is a top view of the structure of this application;

[0031] Figure 4 This is a rear view schematic diagram of the gas separation unit of this application;

[0032] Figure 5 This is an enlarged side-section structural diagram of the gas separation unit of this application;

[0033] Figure 6 This is a side cross-sectional view of the gas-liquid separation component of this application;

[0034] Figure 7 This is a schematic diagram of the internal structure of the gas-liquid separator of this application;

[0035] Figure 8 for Figure 7 A magnified structural diagram of point A in the middle.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Sterilization cabinet; 2. Gas collection unit; 3. Buffer and pressure stabilization unit; 4. Gas separation unit; 5. Nitrogen purification unit; 6. Nitrogen storage unit; 7. Gas-liquid separation assembly;

[0038] 201. Gas collection pipe; 202. Isolation valve;

[0039] 301. Gas buffer tank; 302. Gas analyzer; 303. Gas detection tube; 304. Gas delivery tube;

[0040] 401. Membrane separation module box; 402. Vacuum pump; 403. Multi-stage vacuum fiber membrane module; 404. Nitrogen-rich gas pipe;

[0041] 501. Pressure Swing Adsorption Tower; 502. Switching Valve Assembly; 503. Diverter Pipe; 504. T-shaped Manifold;

[0042] 601. Nitrogen storage tank; 602. Pressure reducing valve assembly; 603. Pressure gauge; 604. Make-up gas pipe; 605. Recovered gas pipe;

[0043] 701. Gas-liquid separator; 702. Air guide pipe; 703. Inlet inclined pipe; 704. Strip brush; 705. Conical collection shell; 706. Annular rubber ring; 707. Impurity removal filter screen; 708. Limiting sliding sleeve; 709. Air guide impeller; 710. Rotating shaft; 711. Rotating plate; 712. Arc-shaped top block; 713. Circular protrusion; 714. Movable frame. Detailed Implementation

[0044] The following is in conjunction with the appendix Figure 1 To be continued Figure 8 This application will be described in further detail below.

[0045] This embodiment discloses a nitrogen replacement system gas recovery and recycling device, which mainly includes a sterilizer 1, a gas collection unit 2, a buffer and pressure stabilizing unit 3, a gas separation unit 4, a nitrogen purification unit 5, a nitrogen storage unit 6, and a gas-liquid separation component 7. The entire set of equipment is equipped with an independent control system to achieve fully automatic linkage control, and is specifically used for the recovery, purification and recycling of nitrogen in the exhaust gas emitted from the nitrogen replacement process of the ethylene oxide sterilizer 1.

[0046] The gas collection unit 2 comprises three main components: a gas collection pipe 201, an isolation valve 202, and a check valve. The inlet end of the gas collection pipe 201 is directly and sealed to the external exhaust pipe port of the sterilizer 1, enabling the directional discharge of the exhaust gas from the sterilizer 1. The isolation valve 202 and the check valve are sequentially mounted on the body of the gas collection pipe 201 along the airflow direction, and the two valve bodies work together to form a bidirectional protection structure.

[0047] The mixed exhaust gas discharged from sterilizer 1 can only be transported in one direction to the rear buffer and pressure stabilizing unit 3. The check valve prevents the backflow of gas and condensate from the rear end back into sterilizer 1. The isolation valve 202 can cut off the gas path of the front and rear pipelines when the equipment is under maintenance or shut down due to failure, so as to achieve segmented isolation maintenance.

[0048] It is worth noting that the exhaust gas is completely captured through a dedicated, sealed collection pipeline with protective valves, with no waste gas being emitted in an unorganized manner. All nitrogen-containing waste gas enters the downstream recovery process, ensuring the nitrogen recovery baseline from the source and laying the foundation for the high nitrogen recovery rate of the unit. At the same time, it avoids the leakage of trace amounts of ethylene oxide waste gas and pollution of the workshop environment.

[0049] The output end of the gas collection pipe 201 is fixedly connected to the flange at the input end of the gas buffer tank 301 of the buffer and pressure stabilizing unit 3, thus completing the transfer of waste gas from the collection unit to the buffer and pressure stabilizing unit.

[0050] The buffer and pressure stabilizing unit 3 includes a gas buffer tank 301, a gas analyzer 302, a gas detection tube 303, and a gas delivery tube 304. The volume of the gas buffer tank 301 is set to 1.5 to 2 times the volume of the sterilizer 1. The large-volume tank can temporarily store and homogenize the fluctuating exhaust gas discharged instantaneously, balance the airflow pressure and component concentration, eliminate the airflow impact caused by the intermittent exhaust of the sterilizer, and ensure the stable air intake conditions of the downstream membrane separation and PSA purification units.

[0051] The gas analyzer 302 is fixedly installed on the upper surface of the gas buffer tank 301. One end of the gas detection tube 303 is connected to the detection chamber of the gas analyzer 302, and the other end extends to the output pipeline of the gas buffer tank 301. It can extract mixed waste gas samples in real time and detect the real-time concentration of oxygen, nitrogen and trace amounts of ethylene oxide in the tank. The output end of the gas analyzer 302 is connected to the gas delivery tube 304, and the end of the gas delivery tube 304 is connected to the inlet of the membrane separation component box 401 of the gas separation unit 4.

[0052] It is worth noting that, on the one hand, the waste gas components are mixed uniformly to avoid drastic concentration fluctuations that could cause instability in the oxygen-nitrogen separation coefficient of the membrane separation and fluctuations in the adsorption efficiency of the PSA adsorption tower; on the other hand, the waste gas components are monitored online in real time, and the control system can automatically adjust the membrane separation operating pressure, the vacuum pump 402 pumping load, and the replenishment flow of the gas replenishment unit based on the detection data, so as to achieve intelligent adjustment of the entire process and improve the accuracy of the automated operation of the whole set of equipment.

[0053] The gas separation unit 4 includes a membrane separation component box 401, a vacuum pump 402, a multi-stage vacuum fiber membrane module 403, and a nitrogen-rich gas pipe 404. The multi-stage vacuum fiber membrane module 403 is vertically arranged inside the membrane separation component box 401. The membrane module is made of polyimide. The initial gas separation is completed by relying on the difference in the permeation rate of oxygen and nitrogen molecules inside the membrane fibers. The permeation rate of oxygen is much higher than that of nitrogen. After the gas enters the membrane module, nitrogen is retained on the inner side of the membrane to form a nitrogen-rich feed gas. Oxygen, water vapor, and ethylene oxide penetrate the membrane wall and enter the permeate side of the membrane shell.

[0054] The vacuum pump 402 is fixedly installed on the permeate side of the membrane separation module box 401. The vacuum pump 402 is used to continuously extract the oxygen-rich mixed gas on the permeate side to form a stable pressure difference of 0.5 to 1.0 MPa on both sides of the membrane fiber, so as to ensure that the oxygen-nitrogen separation is continuous and efficient. The output end of the vacuum pump 402 is equipped with a nitrogen-rich gas pipe 404. The nitrogen-rich gas pipe 404 extends downward to connect to the diversion conduit 503 of the nitrogen purification unit 5, and delivers the nitrogen-rich gas with a purity of 90% to 95% after membrane separation to the dual-tower PSA purification process.

[0055] A gas-liquid separation component 7 is fixedly mounted on the outside of the membrane separation component box 401. The gas-liquid separation component 7 is located between the membrane separation permeate outlet and the vacuum pump 402 inlet, serving as a pre-protection structure for the vacuum pump 402. This is a key structural feature that distinguishes this device from traditional membrane separation nitrogen generation equipment. The gas-liquid separation component 7 mainly consists of a gas-liquid separation cylinder 701, a gas guide pipe 702, an inclined inlet pipe 703, and a conical collection shell 705.

[0056] The permeate side outlet of the membrane separation module box 401 is connected to the inlet inclined pipe 703, which is inclined downward and connected to the lower middle part of the side wall of the gas-liquid separator 701; the top of the gas-liquid separator 701 extends vertically upward through the gas guide pipe 702, and the other end of the gas guide pipe 702 is sealed and connected to the input end of the vacuum pump 402; the bottom of the gas-liquid separator 701 is equipped with a threaded detachable conical collection shell 705, which is used to centrally store condensed liquid water vapor and ethylene oxide waste liquid. The threaded structure facilitates periodic disassembly and emptying of the waste liquid.

[0057] An annular rubber ring 706 is fixed to the inner wall of the gas-liquid separator 701. A conical impurity removal filter 707 is integrally connected to the inner side of the annular rubber ring 706. A limiting sleeve 708 is embedded at the bottom of the filter. A fixed cross frame is erected in the middle of the separator. An air guide impeller 709 is rotatably installed at the center of the cross frame. After the airflow enters the separator, it impacts the blades and drives the impeller to rotate. A rotating shaft 710 is coaxially connected to the bottom of the impeller. The shaft extends downward through the limiting sleeve 708 to below the impurity removal filter 707. A rotating plate 71 is fixed to the bottom of the shaft. 1. Two sets of arc-shaped top blocks 712 are symmetrically arranged on the rotating plate 711. Two sets of circular protrusions 713 are correspondingly set at the bottom of the impurity removal filter screen 707. During the rotation of the impeller, the arc-shaped top blocks 712 continuously push the circular protrusions 713, forming vibration to remove scale from the filter screen. Movable frames 714 extend outward from both ends of the rotating plate 711. A strip brush 704 is fixed on the surface of the movable frame 714. The top surface of the strip brush 704 is closely attached to the inner wall of the conical impurity removal filter screen 707. The rotation of the impeller synchronously drives the brush body to reciprocate along the surface of the filter screen for cleaning.

[0058] It is worth noting that the exhaust gas from ethylene oxide sterilization and replacement carries water vapor and trace amounts of ethylene oxide. After the gas cools down in the membrane shell and pipeline, it is very easy to condense into a liquid medium. Traditional equipment does not have a pre-gas-liquid separation structure, and the accumulated liquid will be directly sucked in by the vacuum pump 402, which will corrode the impeller and cavity of the vacuum pump 402. At the same time, the accumulated liquid accumulates at the bottom of the membrane module box, which soaks the polyimide hollow fiber membrane filaments for a long time, clogging the membrane pores and significantly reducing the oxygen-nitrogen separation efficiency.

[0059] This application places the gas-liquid separation component 7 upstream of the vacuum pump 402. The mixed permeate waste gas enters the cylinder through the inclined inlet pipe 703. The airflow is decelerated by the swirling impeller 709. Under the action of gravity, water vapor and liquid EtO settle to the bottom conical collection shell 705. The conical impurity removal filter 707 intercepts solid dust and colloidal impurities in the waste gas. The self-cleaning brush body linked to the impeller continuously cleans the filter screen to avoid insufficient negative pressure caused by filter screen blockage. The oxygen-enriched gas after drying and dehydration is sent to the vacuum pump 402 from the top of the cylinder through the air guide pipe 702. The liquid medium is isolated from the membrane module and vacuum pump 402 from the source, and the oxygen-nitrogen separation coefficient of the membrane separation is maintained in the range of 3 to 5. This extends the service life of the membrane module and vacuum pump 402, and greatly reduces the frequency of equipment maintenance and maintenance costs. At the same time, the conical collection shell 705 is threaded and detachable, and the waste liquid is collected and treated centrally, reducing the waste liquid treatment pressure of the tail gas treatment system.

[0060] The nitrogen purification unit 5 includes two pressure swing adsorption (PSA) towers 501, a switching valve group 502, a branch pipe 503, and a T-shaped manifold 504. The input end of the branch pipe 503 receives the crude nitrogen-rich gas transported by the nitrogen-rich gas pipe 404. The branch pipe 503 splits into two paths, each connecting to the bottom inlet of one of the two independent PSA towers 501. The PSA tower 501 is filled with carbon molecular sieve adsorption packing. It utilizes the difference in adsorption capacity of the molecular sieve for oxygen and nitrogen to achieve deep deoxygenation. Under high pressure, the carbon molecular sieve selectively adsorbs residual oxygen in the mixed gas, and high-purity nitrogen penetrates the bed and is output from the top of the tower. During the low-pressure regeneration stage, the adsorbed oxygen is desorbed and discharged.

[0061] The top outlets of the two pressure swing adsorption towers 501 are connected to the T-shaped manifold 504. The switching valve group 502 is uniformly installed on the T-shaped manifold 504. The switching valve group 502 is driven by the control system to control the two pressure swing adsorption towers 501 to alternately complete the high-pressure adsorption and low-pressure regeneration processes.

[0062] It is worth noting that the adsorption and regeneration stage of the single-tower PSA purification equipment must be stopped. An interruption in gas supply will cause the nitrogen replacement process in the sterilizer to stop, affecting the continuity of medical device sterilization production. This device uses dual adsorption towers paired with switching valve group 502, operating alternately. One tower adsorbs and produces high-purity nitrogen, while the other tower simultaneously depressurizes and desorbs for regeneration, achieving a stable 24-hour uninterrupted gas supply. After deep PSA purification, the nitrogen purity can reach over 99.5%, meeting the high-purity gas source standard for oxygen removal in ethylene oxide sterilizers. The entire membrane separation + PSA two-stage coupled purification process significantly improves the overall nitrogen recovery rate and reduces fresh nitrogen consumption. Simultaneously, most of the recovered nitrogen is recycled and reused, with only a small amount of oxygen-enriched waste gas sent to the tail gas treatment system. This significantly reduces the total intake of the tail gas treatment system, lowering energy and reagent consumption for tail gas incineration and water washing equipment. The output of the T-shaped manifold 504 connects to the input of the nitrogen storage unit 6, nitrogen tank 601, allowing the purified high-purity nitrogen to be buffered in the storage tank.

[0063] The nitrogen storage unit 6 includes a nitrogen storage tank 601, a pressure reducing valve assembly 602, a pressure gauge 603, a gas supply pipe 604, and a gas recovery pipe 605. The nitrogen storage tank 601 is a pressure-resistant vessel designed to withstand a pressure of 1.0 MPa, used to buffer high-pressure, high-purity nitrogen after purification. The pressure gauge 603 is fixedly installed on the side wall of the nitrogen storage tank 601 to monitor the nitrogen level and pressure in real time, and the pressure data is synchronously transmitted to the control system. The output end of the nitrogen storage tank 601 is connected to the gas recovery pipe 605. The gas recovery pipe 605 is sequentially equipped with the pressure reducing valve assembly 602 along the pipeline. The pressure reducing valve assembly 602 reduces the pressure of the high-pressure nitrogen in the storage tank to the appropriate working pressure of 0.4–0.6 MPa for the sterilizer 1. The end of the gas recovery pipe 605 is connected to the nitrogen replacement inlet circuit inside the sterilizer 1, forming a complete closed-loop cycle of nitrogen sterilization discharge – recovery purification – return for sterilization and reuse.

[0064] The nitrogen storage tank 601 is connected to a gas supply pipe 604 on its side wall. The outer end of the gas supply pipe 604 is connected to an external liquid nitrogen storage tank or a high-purity nitrogen cylinder group as a fresh nitrogen source. A gas supply regulating valve and a flow meter are installed on the gas supply pipe 604 respectively. The control system collects the pressure signal of the pressure gauge 603 of the nitrogen storage tank 601 in real time. When the recovered nitrogen production is insufficient or the pressure inside the tank is lower than the set threshold, the gas supply regulating valve is automatically opened to replenish fresh high-purity nitrogen. The flow meter accurately measures the single and cumulative nitrogen replenishment volume.

[0065] It is worth noting that the storage tank buffer eliminates fluctuations in the gas flow rate of the purification unit, ensuring a stable and continuous gas supply to the sterilization cabinet; the automatic gas replenishment unit makes up for peak gas consumption and nitrogen shortages during maintenance shutdowns, eliminating the need for manual on-site gas replenishment throughout the process. It is highly automated and fully compatible with continuous sterilization production lines in factories, ensuring that sterilization operations will not be interrupted due to insufficient nitrogen reserves.

[0066] The working principle of this embodiment is as follows: First, the exhaust gas from the sterilizer 1 is discharged through the gas collection pipe 201. The isolation valve 202 and the check valve prevent the gas from flowing back. All the exhaust gas is sent into the gas buffer tank 301. The tank, with a volume of 1.5 to 2 times that of the sterilizer, temporarily stores and mixes the intermittently discharged fluctuating exhaust gas. The gas analyzer 302 detects the concentrations of oxygen, nitrogen, and ethylene oxide in the mixed gas in the tank in real time and transmits the component data to the main control system. The mixed and stabilized exhaust gas is then transported to the membrane separation component box 401 through the gas delivery pipe 304.

[0067] In the second step, the mixed waste gas enters the multi-stage polyimide hollow fiber membrane. The control system adjusts the pressure regulating valve before the membrane according to the data from the gas analyzer 302 to stabilize the inlet pressure at 0.5-1.0 MPa. The vacuum pump 402 continuously draws gas on the permeate side of the membrane, forming a stable pressure difference on both sides of the membrane fibers. Oxygen, water vapor, and trace amounts of EtO penetrate the membrane wall and enter the permeate side of the membrane shell. High-concentration nitrogen gas remains inside the membrane to form a nitrogen-rich gas with a purity of 90%-95%. The nitrogen-rich gas is transported to the PSA purification unit through the nitrogen-rich gas pipe 404.

[0068] The oxygen-rich mixed gas, condensed water vapor, and liquid ethylene oxide discharged from the permeate side of the membrane housing enter the gas-liquid separator 701 through the inclined inlet pipe 703. The inclined pipe ensures that the condensate flows into the separator by gravity. The airflow impacts the guide impeller 709 to generate a swirling flow, accelerating the condensation and settling of water vapor. The conical impurity filter 707 intercepts solid impurities in the exhaust gas. The impeller drives the rotating shaft 710 and the rotating plate 711 to rotate synchronously. The arc-shaped top block 712 intermittently impacts the circular protrusion 713 at the bottom of the filter screen to achieve vibration cleaning. The strip brush 707... 04. Continuously wipe the inner wall of the filter screen to prevent the filter screen pores from being blocked by gelatinous condensate and dust; all liquid media settle to the conical collection shell 705 at the bottom of the cylinder for centralized storage; the oxygen-enriched gas after drying and removing the liquid is sent to the vacuum pump 402 through the air guide pipe 702 at the top of the cylinder; the oxygen-enriched waste gas discharged by the vacuum pump 402 is uniformly transported to the plant's tail gas treatment system for incineration and degradation; the conical collection shell 705 adopts a threaded detachable structure, which can be disassembled and emptied by maintenance personnel at regular intervals to avoid secondary backflow of accumulated liquid and contamination of the membrane module.

[0069] In the third step, the crude nitrogen-rich gas is evenly distributed into the bottom of the two pressure swing adsorption towers 501 via the diversion conduit 503. The gas passes through the carbon molecular sieve packing layer inside the tower from bottom to top. Under the high pressure of 0.6-0.8 MPa, the molecular sieve selectively adsorbs the residual oxygen in the mixed gas. High-purity nitrogen gas with a purity of ≥99.5% penetrates the molecular sieve bed and flows out from the top of the pressure swing adsorption tower 501 and merges into the T-shaped collection pipe 504. The switching valve group 502 switches the operating conditions of the two pressure swing adsorption towers 501 at regular intervals by the control system. When one tower is in the high pressure adsorption and gas production state, the other tower is simultaneously depressurized to atmospheric pressure. The oxygen adsorbed by the molecular sieve is desorbed and released. The desorbed waste gas is returned to the tail gas treatment system. The two towers operate alternately to achieve uninterrupted production of high-purity nitrogen gas. The purified nitrogen gas is fed into the nitrogen storage tank 601 for buffering.

[0070] Fourth, high-purity nitrogen is stored in a pressure-resistant nitrogen storage tank 601, and a pressure gauge 603 monitors the amount of gas stored in the tank in real time. When the gas consumption and recovery production of the sterilizer 1 are insufficient and the pressure inside the tank is lower than the system's set lower limit, the control system automatically opens the gas replenishment regulating valve on the gas replenishment pipe 604 to replenish fresh nitrogen from the high-purity nitrogen cylinder group in the external liquid nitrogen storage tank. The flow meter measures the total amount of nitrogen replenished in real time. The high-pressure high-purity nitrogen in the storage tank is reduced to 0.4-0.6 MPa through the pressure reducing valve group 602 on the recovery gas pipe 605 and transported back to the sterilizer 1 for use in the nitrogen replacement and deoxygenation process before sterilization, realizing the closed-loop recycling of nitrogen resources.

Claims

1. A gas recovery and recycling device for a nitrogen replacement system, characterized in that, It includes a sterilizer (1), a gas collection unit (2), a buffer and pressure stabilizing unit (3), a gas separation unit (4), a nitrogen purification unit (5), and a nitrogen storage unit (6). The gas collection unit (2) includes a gas collection pipe (201), the input end of which is fixedly connected to the external exhaust pipe port of the sterilizer (1); The buffer voltage stabilizing unit (3) includes a gas buffer tank (301), the input end of which is fixedly connected to the output end of the gas collection pipe (201); The gas separation unit (4) includes a membrane separation module box (401) and a vacuum pump (402). The vacuum pump (402) is fixedly installed on the permeate side of the membrane separation module box (401). The vacuum pump (402) is used to extract the permeate gas and maintain the pressure difference across the membrane. The nitrogen purification unit (5) includes two pressure swing adsorption towers (501) and a switching valve group (502), which is used to control the alternating adsorption and regeneration of the two adsorption towers. The nitrogen storage unit (6) includes a nitrogen storage tank (601), a pressure reducing valve group (602), and a pressure gauge (603).

2. The nitrogen replacement system gas recovery and recycling device according to claim 1, characterized in that, The gas collection pipe (201) is used to collect the exhaust gas from the sterilization cabinet (1). An isolation valve (202) and a check valve are fixedly installed on the surface of the gas collection pipe (201). The isolation valve (202) and the check valve are used to prevent gas backflow.

3. The nitrogen replacement system gas recovery and recycling device according to claim 2, characterized in that, The volume of the gas buffer tank (301) is 1.5 to 2 times that of the sterilizer (1). The gas buffer tank (301) is used to temporarily store the emitted gas and uniformly mix the gas components.

4. The nitrogen replacement system gas recovery and recycling device according to claim 3, characterized in that, A gas analyzer (302) is fixedly installed on the upper surface of the gas buffer tank (301). A gas detection tube (303) is fixedly installed at the input end of the gas analyzer (302). The end of the gas detection tube (303) away from the gas analyzer (302) extends to the output end of the gas buffer tank (301) and is fixedly connected. A gas delivery tube (304) is fixedly installed at the output end of the gas analyzer (302).

5. A nitrogen replacement system gas recovery and recycling device according to claim 4, characterized in that, The membrane separation component box (401) is equipped with a multi-stage vacuum fiber membrane component (403), and the multi-stage vacuum fiber membrane component (403) is made of polyimide. The multi-stage vacuum fiber membrane component (403) uses the difference in the permeation rate of oxygen and nitrogen in the membrane (the oxygen permeation rate is higher than that of nitrogen) to separate oxygen from the gas.

6. A nitrogen replacement system gas recovery and recycling device according to claim 5, characterized in that, The output end of the vacuum pump (402) is fixedly provided with a nitrogen-rich gas pipe (404), and the input ends of the two pressure swing adsorption towers (501) are fixedly provided with a diversion conduit (503). The output end of the nitrogen-rich gas pipe (404) is fixedly connected to the input end of the diversion conduit (503).

7. A nitrogen replacement system gas recovery and recycling device according to claim 6, characterized in that, The two pressure swing adsorption towers (501) operate in an alternating mode. The interior of the pressure swing adsorption tower (501) is filled with carbon molecular sieves. The carbon molecular sieves have different adsorption capacities for oxygen and nitrogen (oxygen adsorption capacity is greater than nitrogen). Oxygen is adsorbed under high pressure and desorbed under low pressure. A T-shaped manifold (504) is fixedly installed at the top output end of the pressure swing adsorption tower (501). The output end of the T-shaped manifold (504) is fixedly connected to the input end of the nitrogen storage tank (601).

8. A nitrogen replacement system gas recovery and recycling device according to claim 7, characterized in that, The switching valve assembly (502) is fixedly installed on the surface of the T-shaped manifold (504). The output end of the nitrogen storage tank (601) is fixed with a recovery gas pipe (605). The output end of the recovery gas pipe (605) extends into the interior of the sterilizer (1). The pressure reducing valve assembly (602) is fixedly installed on the surface of the recovery gas pipe (605). The pressure reducing valve assembly (602) is used to reduce the pressure of high-pressure nitrogen to the pressure required by the sterilizer (1). The pressure gauge (603) is fixedly installed on the surface of the nitrogen storage tank (601) for monitoring the amount of gas stored. The surface of the nitrogen storage tank (601) is fixedly provided with a gas replenishment pipe (604). The input end of the gas replenishment pipe (604) is connected to a liquid nitrogen storage tank or a high-purity nitrogen cylinder assembly for replenishing fresh nitrogen. The surface of the gas replenishment pipe (604) is provided with a gas replenishment regulating valve and a flow meter. The gas replenishment regulating valve is used to automatically replenish fresh nitrogen when the recovered nitrogen is insufficient. The flow meter is used to measure the amount of nitrogen replenished.

9. A nitrogen replacement system gas recovery and recycling device according to claim 8, characterized in that, The gas separation unit (4) is provided with a gas-liquid separation component (7) on its surface. The gas-liquid separation component (7) includes a gas-liquid separation cylinder (701). The gas-liquid separation cylinder (701) is fixedly installed on one side of the membrane separation component box (401), and a gas guide pipe (702) is fixedly provided at the top output end of the gas-liquid separation cylinder (701). The end of the gas guide pipe (702) away from the gas-liquid separation cylinder (701) is fixedly connected to the input end of the vacuum pump (402). An inlet inclined pipe (703) is fixedly provided at the input end of the gas-liquid separation cylinder (701). The end of the inlet inclined pipe (703) away from the gas-liquid separator (701) is fixedly connected to the output end of the membrane separation component box (401). The bottom end of the gas-liquid separator (701) is threadedly connected to a conical collection shell (705). An annular rubber ring (706) is fixedly provided on the inner wall of the gas-liquid separator (701). A filter screen (707) is fixedly connected to the inner annular surface of the annular rubber ring (706). The filter screen (707) is conical in shape, and a limiting sleeve (708) is fixedly embedded at the bottom end of the filter screen (707).

10. A nitrogen replacement system gas recovery and recycling device according to claim 9, characterized in that, A fixed crossbar is fixedly installed on the inner wall of the gas-liquid separator (701). A guide impeller (709) is rotatably installed at the center of the upper surface of the fixed crossbar. A rotating shaft (710) is fixedly installed at the bottom end of the guide impeller (709). The bottom end of the rotating shaft (710) extends to the bottom of the impurity removal filter (707) and is fixedly connected to a rotating plate (711). The rotating shaft (710) is slidably connected to the inner wall of the limiting sleeve (708). Two arc-shaped top blocks (712) are symmetrically fixed on the upper surface of (711). Two circular protrusions (713) are fixed at the bottom end of the impurity removal filter (707). The position of the circular protrusions (713) corresponds to the arc-shaped top blocks (712). Movable frames (714) are fixed at both ends of the rotating plate (711). A strip brush (704) is fixed on the surface of the movable frame (714). The strip brush (704) overlaps with the surface of the impurity removal filter (707).

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