A system for inert gas closed circuit circulation and purification recovery

Abstract

This invention discloses a system for closed-loop circulation and purification recovery of inert gases, belonging to the field of industrial gas treatment technology. It includes a treatment chamber, outside which, via a return pipe, are sequentially connected a pretreatment and solvent recovery component for gas filtration and solvent classification and recovery, and a purification and power component for purifying the inert gas. Leakage diagnostic components are installed at the inlet and outlet of the treatment chamber. An online oxygen analyzer is installed inside the treatment chamber, and a system controller is located outside the chamber. This invention integrates and optimizes the entire system architecture through the pretreatment and solvent recovery component, purification and power component, and system controller, reducing energy and nitrogen consumption. It lowers operating costs through adaptive adjustment of operating strategies, and ensures the inherent safety of the process and equipment through multiple safeguards such as SIS linkage, safety bypass, and backoff strategies. Furthermore, it can effectively couple with external energy sources such as process waste heat, improving energy utilization.

Description

Technical Field

[0001] This invention belongs to the field of industrial gas treatment technology, specifically relating to a system for closed-loop circulation and purification recovery of inert gases. Background Technology

[0002] In industries such as chemical engineering, pharmaceuticals, and lithium battery drying, inert gases (such as N2) are often used as protective atmospheres.

[0003] During the process, the inert gas carries solvent vapor, moisture, and oxygen; the traditional "single-pass" emission method leads to resource waste and environmental pollution. Existing technologies use condensation and adsorption for purification and recovery, but these methods have the following problems: 1. Poor system coordination: Each unit (condensation, membrane, adsorption) operates independently, lacking overall optimization, resulting in high energy and nitrogen consumption; 2. Outdated control strategies: Mostly using PID setpoint control or simple sequential control, unable to cope with fluctuations in operating conditions, and often overly conservative to ensure safety, leading to high operating costs; 3. Insufficient safety and reliability: Lack of intelligent early warning and adaptive handling mechanisms for risks such as oxygen concentration control, equipment leakage, and adsorbent failure; 4. Low overall energy utilization efficiency: Failure to effectively couple with external energy sources such as process waste heat. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a system for closed-loop circulation and purification recovery of inert gas.

[0005] The technical solution adopted to solve the above-mentioned technical problems is: a system for closed-loop circulation and purification recovery of inert gas, including a processing chamber. A pretreatment and solvent recovery component for filtering the gas and classifying and recovering the solvent, and a purification and power component for purifying the inert gas are connected in series on the outside of the processing chamber via a return pipe. The purification and power component is connected to the processing chamber via the return pipe. A leak diagnosis component for diagnosing system sealing is provided at the inlet and outlet of the processing chamber. An online oxygen analyzer is installed inside the processing chamber. A system controller is located outside the processing chamber. A fresh nitrogen replenishment valve is installed through the side wall of the processing chamber. The system controller, in conjunction with the pretreatment and solvent recovery component, the purification and power component, the online oxygen analyzer, and the leak diagnosis component, maintains O2 ≤ 2% within the processing chamber, monitors the dew point and transmembrane pressure difference online to control regeneration and switching, and simultaneously monitors and diagnoses the system's sealing performance.

[0006] Furthermore, the pretreatment and solvent recovery assembly includes a buffer tank, a particulate filter, and a multi-stage condensation unit. The buffer tank, particulate filter, and multi-stage condensation unit are connected in sequence through pipelines, and valves are installed on the pipelines.

[0007] Through the above technical solution, the gas in the treatment chamber passes sequentially through a buffer tank, a particulate filter, and a multi-stage condensation unit. The buffer tank stabilizes the airflow pulsation from the treatment chamber, the particulate filter removes dust and particulate matter entrained in the airflow, protecting the downstream membrane modules and adsorbents, and the multi-stage condensation unit realizes the stepwise and classified condensation and recovery of volatile organic compound solvents, recovering expensive process solvents from the waste gas, and significantly reducing raw material procurement costs and hazardous waste treatment costs.

[0008] Furthermore, the purification and power assembly includes a gas compressor, a membrane separation assembly, an oil-free screw compressor, and a high-pressure storage tank. The gas compressor, membrane separation assembly, oil-free screw compressor, and high-pressure storage tank are connected in sequence via pipelines. A three-way solenoid valve is installed on the outlet pipe of the high-pressure storage tank. One end of the three-way solenoid valve is connected to a venting branch. The other end of the three-way solenoid valve is connected in sequence via pipelines to an alkaline washing tower and a composite adsorption bed. The composite adsorption bed is connected to the treatment chamber via pipelines.

[0009] The above technical solution employs a multi-stage, synergistic purification process involving membrane separation, alkaline washing, and composite adsorption. The membrane separation component serves as a pretreatment, efficiently removing most of the oxygen and water vapor, thus reducing the load on subsequent units. The alkaline washing tower is specifically designed to remove acidic gases. The composite adsorption bed uses adsorbents such as molecular sieves and activated alumina to deeply remove residual trace amounts of moisture, oxygen, and other impurities. This combination ensures that the purity of the effluent can be stably maintained at an extremely low level of O2≤%, achieving an extremely low dew point, thus meeting the stringent atmospheric requirements of high-end manufacturing and precision scientific research.

[0010] Furthermore, the multi-stage condensing unit includes a primary condenser, a secondary condenser, a tertiary condenser, a gas-liquid separator I, a gas-liquid separator II, and a gas-liquid separator III. The primary condenser, gas-liquid separator I, gas-liquid separator II, gas-liquid separator III, and gas-liquid separator III are sequentially connected by pipelines. The outlet of gas-liquid separator III is connected to the inlet of the gas compressor. Plate heat exchangers are fixedly installed between the inlet and outlet pipelines of the primary condenser, secondary condenser, and tertiary condenser. Flow meters are installed at the outlets of gas-liquid separator I, gas-liquid separator II, and gas-liquid separator III. The other end of each flow meter is connected to a drain pipe. The refrigerant inlet and outlet of the primary condenser are connected to a chiller unit. The refrigerant inlet and outlet of the secondary condenser are connected to a low-temperature ethylene glycol refrigeration unit. The liquid nitrogen cryogenic unit is connected to the tertiary condenser.

[0011] Through the above technical solution, the primary, secondary, and tertiary condensers achieve cascaded and classified condensation and recovery of volatile organic compound (VOC) solvents from cold water, low-temperature ethylene glycol to liquid nitrogen cryogenic cooling. The gas-liquid separator installed after each condenser accumulates and measures the separated liquid through a flow meter, achieving "category-based measurement" and tracking with a recovery rate of no less than 70%, which facilitates subsequent resource utilization. The plate heat exchanger uses purified low-temperature dry gas returned from the end of the system to exchange heat with the high-temperature and high-humidity gas before entering the condenser, improving energy utilization.

[0012] Furthermore, the membrane separation assembly includes several membrane separators arranged in parallel. Each membrane separator is equipped with a back pressure regulating valve at its permeate side port and a pressure regulating valve at its inlet. The parallel inlets of the membrane separators are connected to the outlet of the gas compressor.

[0013] Through the above technical solution, multiple membrane separators arranged in parallel are composed of hollow fiber membranes or spiral wound membranes. They preferentially permeate out fast gases such as O2 and water vapor, leaving purified slow gas N2. The control system dynamically adjusts the back pressure regulating valve and the pressure regulating valve based on the PIT readings of the pressure sensors on the high-pressure side and the permeate side, so as to accurately stabilize the pressure difference within the optimal range of 0.3–1.5 MPa, balancing separation efficiency and energy consumption.

[0014] Furthermore, the composite adsorption bed includes adsorption towers and a heater. Two adsorption towers are provided and arranged in parallel. Three-way solenoid valves three and two, respectively, are installed at the parallel inlet and outlet of the two adsorption towers. Dew point sensors are fixedly installed at the outlets of both adsorption towers. The inlet of three-way solenoid valve two is connected to the outlet of the alkaline washing tower via a pipeline. The outlet of three-way solenoid valve three is connected to the side wall of the processing chamber via a pipeline, and a nitrogen valve is installed at the outlet end of the pipeline. The two outlets of the heater are respectively connected to the two adsorption towers, and solenoid valves are installed on both ports of the heater. An exhaust pipe is provided at the top of each adsorption tower, and a vent valve is installed on each exhaust pipe.

[0015] With the above technical solution, during normal operation, one of the two adsorption towers is used for adsorption and the other is used for regeneration or standby. The towers are filled with molecular sieves and activated carbon to adsorb residual water and organic solvents and keep the recovered inert gas dry. When the dew point sensor at the outlet of one adsorption tower detects that the dew point has risen to the threshold, the control system automatically triggers the regeneration program and switches the main channel to the other standby adsorption tower. The heater blows a stream of dry hot gas back to purge the saturated adsorption bed, regenerating the adsorption bed. This allows for seamless connection between the use and regeneration of the adsorption bed while the system is running without stopping, significantly improving the system's operating efficiency.

[0016] Furthermore, the leak diagnosis component includes a tracer gas storage tank and a high-precision flow meter. A gas injection device is fixedly installed at the opening of the tracer gas storage tank, and a flow controller is installed through the port of the gas injection device. The outlet of the flow controller is connected through to the side wall of the processing chamber. Two high-precision flow meters are respectively installed at the inlet and outlet of the pipeline that communicates with the processing chamber.

[0017] Through the above technical solution, the tracer gas storage tank injects a trace amount of tracer gas into the system periodically or continuously through the injection device. The tracer gas concentration and total mass flow rate at the inlet and outlet of the system are monitored by a high-precision flow meter. Based on the mass balance model, the leakage rate of the system can be estimated.

[0018] Furthermore, the system controller includes a SIS safety instrumented system, an MPC intelligent controller, a leak diagnosis module, and an energy recovery module. The SIS safety instrumented system is electrically connected to an online oxygen analyzer, a three-way solenoid valve, and a fresh nitrogen replenishment valve. The MPC intelligent controller is electrically connected to a gas compressor, a multi-stage condenser unit, an oil-free screw compressor, a back pressure regulating valve, a pressure regulating valve, and a reflux regulating valve. The leak diagnosis module is electrically connected to a flow controller and a high-precision flow meter. The energy recovery module is electrically connected to three-way solenoid valves, a heater, a solenoid valve, a dew point sensor, and a vent valve. The energy recovery module, the leak diagnosis module, the SIS safety instrumented system, and the MPC intelligent controller are electrically connected.

[0019] Through the above technical solution, the SIS (Safety Instrumented System) will override control when the oxygen analyzer detects an O2 concentration approaching 2%, immediately opening the emergency fresh nitrogen replenishment valve to inject high-purity nitrogen into the chamber until the O2 concentration returns to a safe range. Simultaneously, when the system detects abnormal conditions such as overpressure or compressor failure, the SIS will instruct the three-way solenoid valve to actuate, directly guiding untreated or partially treated gas to the vent branch to prevent damage to the main circuit equipment. The MPC (Multi-Purpose Control Controller) is capable of adaptive weighting. When the MPC predicts an impending violation of core safety constraints (such as excessive O2), it will immediately trigger an avoidance strategy, forcibly switching the control command to a safe mode to prioritize the safety of the processing chamber. Simultaneously, the MPC communicates with the energy recovery module to obtain real-time waste heat and temperature data from the drying / pyrolysis section. When sufficient waste heat is available, the MPC will decide to switch the adsorption bed regeneration heat source from electricity to waste heat, significantly reducing power consumption.

[0020] The beneficial effects of this invention are as follows: (1) The architecture of the inert gas purification unit was integrated and optimized by setting up pretreatment and solvent recovery components, purification and power components, reducing energy consumption and nitrogen consumption, ensuring that the purity of the gas outlet can be stably maintained at an extremely low level of O2≤2%, and achieving an extremely low dew point, which meets the requirements of high-end manufacturing. At the same time, the volatile organic compound (VOCs) solvent was condensed and recovered in stages and categories, resulting in higher purity, which facilitates subsequent resource utilization, significantly reducing the cost of raw material procurement and hazardous waste treatment. In addition, the inert gas is recycled in the system, which greatly reduces the amount of fresh high-purity inert gas to be replenished, and significantly reduces the operating cost. (2) Through the system controller, online oxygen analyzer, and fresh nitrogen replenishment valve, the dynamic coordination and optimization of multiple variables is realized through MPC, which significantly reduces the overall operating cost of the system; the system can adaptively adjust the operating strategy according to the changes in production capacity, electricity price, and gas source composition, and has a high degree of intelligence; through SIS linkage, safety bypass, and retreat strategy, the inherent safety of the process and equipment is ensured. (3) By setting up a leak diagnosis component, based on the leak self-diagnosis function of tracer gas, it can provide early warning of micro gas leaks, quickly locate the fault point, guide maintenance, and reduce downtime. (4) Through the plate heat exchanger, energy recovery module and composite adsorption bed, the plate heat exchanger recovers cold energy between the condensers at each stage, and the heater is used for energy recovery after the adsorption bed is regenerated. All of these greatly reduce the overall cooling and heating power consumption of the system. Attached Figure Description

[0021] Figure 1 This invention relates to a three-dimensional system for closed-loop circulation and purification recovery of inert gases. Figure 1 ; Figure 2 This invention relates to a three-dimensional system for closed-loop circulation and purification recovery of inert gases. Figure 2 ; Figure 3 This is a top view of a system for closed-loop circulation and purification recovery of inert gases according to the present invention; Figure 4 This is a perspective view of a leak diagnosis component for a closed-loop circulation and purification recovery system for inert gases according to the present invention. Figure 5 This is a three-dimensional view of a multi-stage condensation unit of a system for closed-loop circulation and purification recovery of inert gases according to the present invention; Figure 6 This is a perspective view of a membrane separation component for a closed-loop circulation and purification recovery system for inert gases according to the present invention. Figure 7 This is a three-dimensional view of a composite adsorption bed for a closed-loop circulation and purification recovery system for inert gases according to the present invention. Figure 8 This is a system controller structure diagram of a system for closed-loop circulation and purification recovery of inert gas according to the present invention; Figure 9 This is a flowchart of a system for closed-loop circulation and purification recovery of inert gas according to the present invention.

[0022] Figure reference numerals: 1. Processing chamber; 2. Pretreatment and solvent recovery assembly; 3. Purification and power assembly; 4. System controller; 5. Leak diagnosis assembly; 6. Online oxygen analyzer; 7. Fresh nitrogen replenishment valve; 201. Buffer tank; 202. Particulate filter; 203. Multistage condensation unit; 301. Gas compressor; 302. Membrane separation assembly; 303. Oil-free screw compressor; 304. High-pressure storage tank; 305. Three-way solenoid valve; 306. Venting branch; 307. Alkali washing tower; 308. Composite adsorption bed; 401. SIS safety instrumented system; 402. MPC intelligent controller; 403. Leak diagnosis module; 404. Energy recovery module; 501. Tracer gas storage tank; 502. Gas injection... Inlet device; 503, Flow controller; 504, High-precision flow meter; 2031, Primary condenser; 2032, Secondary condenser; 2033, Tertiary condenser; 2034, Gas-liquid separator I; 2035, Gas-liquid separator II; 2036, Gas-liquid separator III; 2037, Flow meter; 2038, Drain pipe; 2039, Plate heat exchanger; 3021, Membrane separator; 3022, Back pressure regulating valve; 3023, Pressure regulating valve; 3081, Adsorption tower; 3082, Three-way solenoid valve II; 3083, Three-way solenoid valve III; 3084, Heater; 3085, Solenoid valve; 3086, Dew point sensor; 3087, Reflux regulating valve; 3088, Exhaust pipe; 3089, Vent valve. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] like Figures 1-9As shown, this embodiment of a system for closed-loop circulation and purification recovery of inert gas includes a processing chamber 1. A pretreatment and solvent recovery assembly 2 for filtering the gas and classifying and recovering the solvent, and a purification and power assembly 3 for purifying the inert gas are connected in series via a return pipe on the outside of the processing chamber 1. The purification and power assembly 3 is connected to the processing chamber 1 via the return pipe. A leak diagnosis assembly 5 for diagnosing system sealing is provided at the inlet and outlet of the processing chamber 1. An online oxygen analyzer 6 is installed inside the processing chamber 1. A system controller 4 is provided outside the processing chamber 1. A fresh nitrogen replenishment valve 7 is installed through the side wall of the processing chamber 1. The system controller 4, in conjunction with the pretreatment and solvent recovery assembly 2, the purification and power assembly 3, the online oxygen analyzer 6, and the leak diagnosis assembly 5, maintains O2 ≤ 2% inside the processing chamber 1, monitors the dew point and transmembrane pressure difference online to control regeneration and switching, and simultaneously monitors and diagnoses the system's sealing performance. The pretreatment and solvent recovery assembly 2 includes a buffer tank 201, a particulate filter 202, and a multi-stage condensation unit 203. The buffer tank 201, particulate filter 202, and multi-stage condensation unit 203 are connected sequentially by pipelines, and valves are installed on the pipelines. The gas in the treatment chamber 1 passes sequentially through the buffer tank 201, particulate filter 202, and multi-stage condensation unit 203. The buffer tank 201 stabilizes the airflow pulsation from the treatment chamber 1, providing a stable gas source point for the entire system. It is equipped with a pressure transmitter to send the signal to the control system. The particulate filter 202 removes dust and particulate matter entrained in the airflow, protecting the downstream membrane module and adsorbent. It is equipped with a differential pressure switch, which alarms when the differential pressure exceeds the set value, prompting the replacement of the filter element. The multi-stage condensation unit 203 realizes the step-by-step and classified condensation and recovery of volatile organic compound solvents, recovering expensive process solvents from the waste gas, significantly reducing raw material procurement costs and hazardous waste treatment costs. The purification and power assembly 3 includes a gas compressor 301, a membrane separation assembly 302, an oil-free screw compressor 303, and a high-pressure storage tank 304. The gas compressor 301, membrane separation assembly 302, oil-free screw compressor 303, and high-pressure storage tank 304 are sequentially connected by pipelines. A three-way solenoid valve 305 is installed on the outlet pipe of the high-pressure storage tank 304. One end of the three-way solenoid valve 305 is connected to a vent branch 306, and the other end of the three-way solenoid valve 305 is sequentially connected by pipelines to an alkaline washing tower 307 and a composite adsorption bed 308. The composite adsorption bed 308 is connected to the treatment chamber 1 by a pipeline, employing a multi-stage, synergistic approach of membrane separation, alkaline washing, and composite adsorption. In the purification process, membrane separation component 302 serves as a pretreatment, efficiently removing most oxygen and water vapor, reducing the load on subsequent units. The alkaline washing tower 307 is filled with Pall rings and other packing materials, and sprayed with alkaline solutions such as NaOH from the top, specifically targeting acidic gases (such as CO2 and SO2), components that are difficult to completely remove through physical adsorption. The composite adsorption bed 308 serves as a fine treatment unit, deeply removing residual trace amounts of moisture, oxygen, and other impurities through adsorbents such as molecular sieves and activated alumina. This combination ensures that the purity of the effluent is stably maintained at an extremely low level of O2 ≤ 2%, achieving an extremely low dew point (e.g., below -70℃), meeting the stringent atmospheric requirements of high-end manufacturing and precision scientific research. Furthermore, a high-pressure storage tank 304 provides reflux power for the purified gas and acts as a buffer and guarantee for the system's gas volume. The oil-free screw compressor 303 uses a variable frequency drive (VFD) to regulate the "circulating air volume." The three-way solenoid valve 305 is designed to directly guide untreated or partially treated gas to the vent branch 306 under abnormal operating conditions, preventing damage to the main circuit equipment. The multi-stage condensing unit 203 includes a primary condenser 2031, a secondary condenser 2032, a tertiary condenser 2033, a first gas-liquid separator 2034, a second gas-liquid separator 2035, and a third gas-liquid separator 2036. These components are sequentially connected by pipelines. The outlet of the third gas-liquid separator 2036 is connected to the inlet of the gas compressor 301. Plate heat exchangers 2039 are fixedly installed between the inlet and outlet pipes of the primary condenser 2031, secondary condenser 2032, and tertiary condenser 2033. Flow meters 2037 are installed at the outlets of the first gas-liquid separator 2034, second gas-liquid separator 2035, and third gas-liquid separator 2036. The system is connected by a drain pipe 2038. The refrigerant inlet and outlet of the first-stage condenser 2031 are connected to the chiller unit, the refrigerant inlet and outlet of the second-stage condenser 2032 are connected to the low-temperature ethylene glycol refrigeration unit, and the liquid nitrogen cryogenic unit is connected to the third-stage condenser 2033. The first-stage condenser 2031, the second-stage condenser 2032, and the third-stage condenser 2033 achieve cascaded and classified condensation and recovery of volatile organic compound (VOC) solvents from chilled water, low-temperature ethylene glycol, to liquid nitrogen cryogenic refrigeration. A gas-liquid separator is installed after each condenser. The separated liquid is cumulatively metered by a flow meter 2037, achieving "metering by category" and tracking with a recovery rate of not less than 70%. Solvents with different boiling points are condensed and recovered separately at different temperature ranges, resulting in higher purity and facilitating subsequent resource utilization. This reduces VOC emissions at the source, complies with the strictest environmental regulations, and has significant environmental benefits. Plate heat exchanger 2039 utilizes purified low-temperature dry gas returned from the end of the system to exchange heat with high-temperature and high-humidity gas before entering the condenser. It pre-cools the inlet gas, reduces the load on the condenser unit, saves electricity, and preheats the return gas to prevent condensation at the inlet of the processing chamber 1. It also increases the surface temperature of the condenser and effectively avoids blockage caused by condensation and frost. The membrane separation module 302 includes several membrane separators 3021 arranged in parallel. Each membrane separator 3021 has a back pressure regulating valve 3022 installed at its permeate side port and a pressure regulating valve 3023 installed at its inlet. The parallel inlets of the membrane separators 3021 are connected to the outlet of the gas compressor 301. The multiple membrane separators 3021 arranged in parallel are composed of hollow fiber membranes or spiral wound membranes. By utilizing the difference in the dissolution and diffusion rates of gas components in the membrane material, fast gases such as O2 and water vapor are preferentially permeated away, leaving purified slow gas N2. The control system dynamically adjusts the back pressure regulating valve 3022 and the pressure regulating valve 3023 based on the PIT readings of the pressure sensors on the high-pressure side and the permeate side, so as to accurately stabilize the pressure difference within the optimal range of 0.3–1.5 MPa, taking into account both separation efficiency and energy consumption. The composite adsorption bed 308 includes adsorption towers 3081 and heaters 3084. Two adsorption towers 3081 are provided and arranged in parallel. Three-way solenoid valves 3083 and 3082 are respectively installed at the parallel inlet and outlet of the two adsorption towers 3081. Dew point sensors 3086 are fixedly installed at the outlets of both adsorption towers 3081. The inlet of three-way solenoid valve 3082 is connected to the outlet of the alkaline washing tower 307 via a pipeline. The outlet of three-way solenoid valve 3083 is connected to the side wall of the processing chamber 1 via a pipeline, and a reflux regulating valve 3087 is installed at the outlet end of the pipeline. The two outlets of the heater 3084 are respectively connected to the two adsorption towers 3081. Solenoid valves 3085 are installed on both ports of the heater 3084. Exhaust pipes 3088 are provided at the top of each adsorption tower 3081, and vent valves are installed on each exhaust pipe 3088. During normal operation, the two adsorption towers 3081, one for adsorption and the other for regeneration or standby, are filled with molecular sieves and activated carbon to adsorb residual water and organic solvents and keep the recovered inert gas dry. When the dew point sensor 3086 at the outlet of one adsorption tower 3081 detects that the dew point has risen to the threshold, the control system automatically triggers the regeneration program, starts the three-way solenoid valve 2 3082, three-way solenoid valve 3083 and solenoid valve 3085 to switch the regeneration channel, and switches the main channel to another standby adsorption tower 3081. The heater 3084 blows a stream of dry hot gas in the opposite direction to sweep the saturated adsorption bed to regenerate the adsorption bed. The desorbed pollutants are discharged directly through the exhaust pipe 3088 and the vent valve 3089 or discharged to the external waste gas treatment system. This allows for seamless connection between the use and regeneration of the adsorption bed while the system is running without stopping, ensuring the continuity of production. The leak diagnosis component 5 includes a tracer gas storage tank 501 and a high-precision flow meter 504. A gas injection device 502 is fixedly installed at the inlet of the tracer gas storage tank 501. A flow controller 503 is installed through the port of the gas injection device 502. The outlet of the flow controller 503 is connected through to the side wall of the processing chamber 1. Two high-precision flow meters 504 are respectively installed at the inlet and outlet of the pipeline connected to the processing chamber 1. The tracer gas storage tank 501 injects a trace amount of tracer gas (such as hexafluorocarbon) into the system periodically or continuously through the gas injection device 502. (Sulfur or helium) The high-precision flow meter 504 monitors the concentration of tracer gas and the total mass flow rate at the inlet and outlet of the system, which can quantitatively and accurately diagnose minor leaks in the system and issue early warnings. Based on the mass balance model, the leakage rate of the system can be estimated, avoiding gas loss, purity reduction and safety risks caused by leaks. Afterwards, a portable tracer gas detector can be used to inspect suspected points such as pipe flanges and valves, or multiple sampling points can be set in different sections of the system to quickly locate the specific leak location and carry out timely repairs. System controller 4 includes a SIS safety instrumented system 401, an MPC intelligent controller 402, a leak diagnosis module 403, and an energy recovery module 404. The SIS safety instrumented system 401 is electrically connected to the online oxygen analyzer 6, the three-way solenoid valve 305, and the fresh nitrogen replenishment valve 7. The MPC intelligent controller 402 is electrically connected to the gas compressor 301, the multi-stage condenser unit 203, the oil-free screw compressor 303, the back pressure regulating valve 3022, the pressure regulating valve 3023, and the reflux regulating valve 3087. The leak diagnosis module 403 is electrically connected to the flow controller 503 and the high-precision flow meter 504. The energy recovery module 404 is electrically connected to the three-way solenoid valve 3082, the three-way solenoid valve 3083, the heater 3084, the solenoid valve 3085, the dew point sensor 3086, and the vent valve 3089. The energy recovery module 404, the leak diagnosis module 403, and the SIS safety instrument system 401 are electrically connected to the MPC intelligent controller 402. When the online oxygen analyzer 6 detects that the O2 concentration is close to 2%, the SIS safety instrument system 401 will override the control and immediately open the emergency fresh nitrogen replenishment valve 7 to inject high-purity nitrogen into the cavity until the O2 concentration returns to the safe range. Simultaneously, when the system detects abnormal operating conditions such as overpressure or compressor failure, the SIS system will instruct the three-way solenoid valve 305 to activate, directly guiding untreated or partially treated gas to the vent branch 306 to prevent damage to the main circuit equipment. The configured MPC intelligent controller 402 is capable of adaptive weighting; the weighting coefficients α and β in the controller are not fixed, but are dynamically adjusted based on real-time electricity prices obtained from the energy management system and the system's capacity (t / h). The MPC intelligent controller 402 predicts the system's behavior over a future period within a rolling time domain and calculates the optimal operating instructions, which are then sent to each actuator. The system's prediction time domain and sampling period are not fixed. Under stable operating conditions, a longer time domain and slower sampling are used to save computing power. Under extreme operating conditions such as drastic load changes, it automatically switches to a shorter time domain and faster sampling to respond quickly. When MPC predicts that a violation of core safety constraints (such as O2 exceeding the standard) is about to occur, it will immediately trigger the backoff strategy. At this time, the goal of minimizing nitrogen consumption is temporarily put aside, and the control command is forcibly switched to the safety mode, which greatly increases the pre-spray amount of nitrogen supplemented by the fresh nitrogen supplement valve 7, reduces the circulating air volume, and even suspends some purification units to prioritize the safety of the treatment chamber 1. Meanwhile, the MPC intelligent controller 402 communicates with the energy recovery module 404. The heater 3084 of the adsorption bed regeneration gas is a dual-source heat exchanger with switchable heat sources. The MPC intelligent controller 402 obtains the waste heat and temperature of the drying / pyrolysis section in real time. When there is sufficient waste heat, the MPC will decide to switch the adsorption bed regeneration heat source from electricity to waste heat, which will greatly reduce power consumption. When waste heat is predicted, the number of regeneration cycles of the adsorption bed will be advanced or increased to achieve "peak shaving and valley filling" energy scheduling and greatly improve resource utilization.

[0025] The working principle of this embodiment is as follows: During use, the gas in the processing chamber 1 passes sequentially through the buffer tank 201 and the particulate filter 202. The particulate filter 202 removes dust and particulate matter entrained in the gas flow. The filtered gas then passes sequentially through the first-stage condenser 2031, the first gas-liquid separator 2034, the second-stage condenser 2032, the second gas-liquid separator 2035, the third-stage condenser 2033, and the third gas-liquid separator 2036. The first-stage condenser 2031, the second-stage condenser 2032, and the third-stage condenser 2033 achieve the stepped and classified condensation of volatile organic compound (VOC) solvents from cold water and low-temperature ethylene glycol to deep cryogenic liquid nitrogen, and recover them through the gas-liquid separator. At the same time, the plate heat exchanger 2039 uses the purified low-temperature dry gas returning from the end of the system to exchange heat with the high-temperature and high-humidity gas before entering the condenser, pre-cooling the inlet gas and preheating the return gas, thereby improving energy utilization. The condensed gas sequentially passes through a gas compressor 301, a membrane separation unit 302, an oil-free screw compressor 303, a high-pressure storage tank 304, an alkaline scrubbing tower 307, and a composite adsorption bed 308. The membrane separation unit 302 serves as a pretreatment process, utilizing the difference in dissolution and diffusion rates of gas components within the membrane material to preferentially remove fast gases such as O2 and water vapor, leaving purified slow gas N2, thus reducing the load on subsequent units. The control system dynamically adjusts the back pressure regulating valve 3022 and the pressure regulating valve 3023 based on the PIT readings from the high-pressure side and the permeate side, precisely stabilizing the pressure difference between 0.3 and 1.5 MPa. Within the optimal range, balancing separation efficiency and energy consumption, the gas is then compressed by an oil-free screw compressor 303 and stored in a high-pressure storage tank 304. An alkaline washing tower 307 removes acidic gases from the gas stream. A composite adsorption bed 308 serves as a fine treatment unit, deeply removing residual trace amounts of moisture, oxygen, and other impurities through the adsorbent. Finally, the purified inert gas is returned to the treatment chamber 1, ensuring that the purity of the effluent can be stably maintained at an extremely low level of O2≤2% and achieving an extremely low dew point (such as below -70℃), meeting the stringent requirements of high-end manufacturing and precision scientific research for the atmospheric environment. When adsorbing gas, two adsorption towers 3081 are used, one for adsorption and the other for regeneration or standby. The towers are filled with molecular sieves and activated carbon to adsorb residual water and organic solvents and keep the recovered inert gas dry. When the dew point sensor 3086 at the outlet of one adsorption tower 3081 detects that the dew point has risen to the threshold, the control system automatically triggers the regeneration program, starts the three-way solenoid valve 3082, the three-way solenoid valve 3083 and the solenoid valve 3085 to switch the regeneration channel, and switches the main channel to the other standby adsorption tower 3081. The heater 3084 blows a stream of dry hot gas back to sweep the saturated adsorption bed to regenerate the adsorption bed. The desorbed pollutants are discharged directly through the exhaust pipe 3088 and the vent valve 3089 or discharged to the external waste gas treatment system. The use and regeneration of the adsorption bed can be seamlessly connected when the system is running without stopping. While in operation, the tracer gas storage tank 501 injects trace amounts of tracer gas into the system periodically or continuously through the gas injection device 502. The tracer gas concentration and total mass flow rate at the system inlet and outlet are monitored by the high-precision flow meter 504. This allows for the quantitative and accurate diagnosis of minor leaks in the system and the early warning. Based on the mass balance model, the system's leakage rate can be estimated. By using a portable tracer gas detector to inspect suspicious points such as pipe flanges and valves, or by setting multiple sampling points in different sections of the system, the specific leak location can be quickly located and repairs can be carried out in a timely manner. When the online oxygen analyzer 6 detects that the O2 concentration is close to 2%, the SIS system will override and immediately open the emergency fresh nitrogen replenishment valve 7 to inject high-purity nitrogen into the chamber until the O2 concentration returns to a safe range. Meanwhile, when the system detects abnormal conditions such as overpressure or compressor failure, the SIS system will instruct the three-way solenoid valve 305 to operate, directly guiding the untreated or partially treated gas to the vent branch 306 to prevent damage to the main circuit equipment. When the MPC predicts that the core safety constraints will be violated, it will immediately trigger the backoff strategy. At this time, the goal of minimizing nitrogen consumption is temporarily put aside, and the control command will be forcibly switched to the safety mode, which will significantly increase the pre-injection amount of nitrogen supplemented by the fresh nitrogen replenishment valve 7, reduce the circulating air volume, and even suspend some purification units to prioritize the safety of the treatment chamber 1. The system operates fully automatically. From solvent condensation and recovery, membrane separation, adsorption regeneration to leak diagnosis, the entire process is automatically managed by the system controller 4, which greatly reduces the dependence on operators and the risk of human error. In addition, the system continuously monitors and records key parameters such as dew point, differential pressure, oxygen content, and flow rate, providing complete data support for equipment status assessment, fault diagnosis and process optimization, making maintenance work more targeted.

[0026] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A system for closed-loop circulation and purification recovery of inert gas, comprising a processing chamber (1), characterized in that: The processing chamber (1) is connected in series via a return pipe to a pretreatment and solvent recovery component (2) for filtering the gas and classifying and recovering the solvent, and a purification and power component (3) for purifying inert gas. The purification and power component (3) is connected to the processing chamber (1) via a return pipe. A leak diagnosis component (5) for diagnosing the system's sealing is provided at the inlet and outlet of the processing chamber (1). An online oxygen analyzer (6) is installed inside the processing chamber (1). A system controller (4) is provided outside the processing chamber (1). A fresh nitrogen replenishment valve (7) is installed through the side wall of the processing chamber (1). The system controller (4) links the pretreatment and solvent recovery component (2), the purification and power component (3), the online oxygen analyzer (6), and the leak diagnosis component (5) to maintain O2 ≤ 2% in the processing chamber (1), and monitors the dew point and transmembrane pressure difference online to control regeneration and switching, while monitoring and diagnosing the system's sealing.

2. The system for closed-loop circulation and purification recovery of inert gas according to claim 1, characterized in that, The pretreatment and solvent recovery assembly (2) includes a buffer tank (201), a particulate filter (202), and a multi-stage condensation unit (203). The buffer tank (201), the particulate filter (202), and the multi-stage condensation unit (203) are connected in sequence through pipelines, and valves are installed on the pipelines.

3. The system for closed-loop circulation and purification recovery of inert gas according to claim 1, characterized in that, The purification and power assembly (3) includes a gas compressor (301), a membrane separation assembly (302), an oil-free screw compressor (303), and a high-pressure storage tank (304). The gas compressor (301), membrane separation assembly (302), oil-free screw compressor (303), and high-pressure storage tank (304) are connected in sequence through pipelines. A three-way solenoid valve (305) is installed on the outlet pipe of the high-pressure storage tank (304). One end of the outlet of the three-way solenoid valve (305) is connected to a venting branch (306). The other end of the outlet of the three-way solenoid valve (305) is connected in sequence through pipelines to an alkaline washing tower (307) and a composite adsorption bed (308). The composite adsorption bed (308) is connected to the treatment chamber (1) through pipelines.

4. A system for closed-loop circulation and purification recovery of inert gas according to claim 2, characterized in that, The multi-stage condensing unit (203) includes a primary condenser (2031), a secondary condenser (2032), a tertiary condenser (2033), a gas-liquid separator I [2034], a gas-liquid separator II [2035], and a gas-liquid separator III [2036]. The primary condenser (2031), gas-liquid separator I [2034], secondary condenser (2032), gas-liquid separator II [2035], tertiary condenser (2033), and gas-liquid separator III [2036] are connected sequentially by pipelines. The outlet of gas-liquid separator III [2036] is connected to the inlet of the gas compressor (301). The primary condenser (2031)... Plate heat exchangers (2039) are fixedly installed between the inlet and outlet pipes of the first-stage condenser (2032) and the third-stage condenser (2033). Flow meters (2037) are installed through the liquid outlets of the first gas-liquid separator (2034), the second gas-liquid separator (2035), and the third gas-liquid separator (2036). The other end of each flow meter (2037) is connected to a drain pipe (2038). The refrigerant inlet and outlet of the first-stage condenser (2031) are connected to a chiller unit. The refrigerant inlet and outlet of the second-stage condenser (2032) are connected to a low-temperature ethylene glycol refrigeration unit. The liquid nitrogen cryogenic unit is connected to the third-stage condenser (2033).

5. A system for closed-loop circulation and purification recovery of inert gas according to claim 3, characterized in that, The membrane separation assembly (302) includes several membrane separators (3021) arranged in parallel. Each membrane separator (3021) has a back pressure regulating valve (3022) installed at its permeate side port and a pressure regulating valve (3023) installed at its inlet. The parallel inlets of several membrane separators (3021) are connected to the outlet of the gas compressor (301).

6. A system for closed-loop circulation and purification recovery of inert gas according to claim 3, characterized in that, The composite adsorption bed (308) includes an adsorption tower (3081) and a heater (3084). There are two adsorption towers (3081) arranged in parallel. The parallel inlet and outlet of the two adsorption towers (3081) are respectively equipped with a three-way solenoid valve three (3083) and a three-way solenoid valve two (3082). A dew point sensor (3086) is fixedly installed at the outlet of each of the two adsorption towers (3081). The inlet of the three-way solenoid valve two (3082) is connected to the outlet of the alkaline washing tower (307) through a pipeline. The outlet of the three-way solenoid valve (3083) is connected to the side wall of the processing chamber (1) through a pipeline, and a reflux regulating valve (3087) is installed at the outlet end of the pipeline. The two outlets of the heater (3084) are respectively connected to the two adsorption towers (3081). Solenoid valves (3085) are installed on both ports of the heater (3084). An exhaust pipe (3088) is provided at the top of each adsorption tower (3081), and a venting valve (3089) is installed on each exhaust pipe (3088).

7. A system for closed-loop circulation and purification recovery of inert gas according to claim 1, characterized in that, The leak diagnosis component (5) includes a tracer gas storage tank (501) and a high-precision flow meter (504). A gas injection device (502) is fixedly installed at the opening of the tracer gas storage tank (501). A flow controller (503) is installed through the port of the gas injection device (502). The outlet of the flow controller (503) is connected through to the side wall of the processing chamber (1). Two high-precision flow meters (504) are respectively installed at the inlet and outlet of the pipeline that is connected to the processing chamber (1).

8. A system for closed-loop circulation and purification recovery of inert gas according to claim 1, characterized in that: The system controller (4) includes a SIS safety instrumented system (401), an MPC intelligent controller (402), a leak diagnosis module (403), and an energy recovery module (404). The SIS safety instrumented system (401) is electrically connected to an online oxygen analyzer (6), a three-way solenoid valve (305), and a fresh nitrogen replenishment valve (7). The MPC intelligent controller (402) is connected to a gas compressor (301), a multi-stage condensing unit (203), an oil-free screw compressor (303), a back pressure regulating valve (3022), a pressure regulating valve (3023), and a reflux regulating valve. The valve (3087) is electrically connected. The leakage diagnosis module (403) is electrically connected to the flow controller (503) and the high-precision flow meter (504). The energy recovery module (404) is electrically connected to the three-way solenoid valve two (3082), the three-way solenoid valve three (3083), the heater (3084), the solenoid valve (3085), the dew point sensor (3086), and the vent valve (3089). The energy recovery module (404), the leakage diagnosis module (403), the SIS safety instrumented system (401) and the MPC intelligent controller (402) are electrically connected.

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