Methane removal oxygen purification system and purification method

Abstract

The invention discloses a methane-removing oxygen purification system and a process method. The preparation of high-purity oxygen is realized by coupling catalytic oxidation and adsorption regeneration. The system comprises a catalysis barrel, a gas-gas heat exchanger, a water-cooling heat exchanger, a double-adsorption barrel and a PLC control system. Raw material gas is subjected to heat exchange and then enters a catalysis barrel, methane and oxygen are completely oxidized into CO2 and H2O under the action of a Pt-Pd catalyst at the temperature of 380-420 DEG C, and the CH4 conversion rate is larger than or equal to 99.9%. Reaction heat is recycled through the coaxial countercurrent heat exchanger, and the total heat efficiency is larger than or equal to 70%. The purified gas is cooled and then enters an adsorption barrel filled with three layers of adsorbents including a 5molecular sieve, modified silica gel and high-silica zeolite, and impurities are deeply removed. The two adsorption barrels operate in parallel, regeneration is triggered by adopting an accumulated operation time criterion algorithm, regenerated gas is heated to 250 DEG C for reverse desorption, and the PID temperature control precision is + / -2 DEG C. And stable pressure-equalizing switching is realized through pressure difference feedback control after cold blowing. The system integrates PLC automatic control, key nodes are provided with sampling and bypass interfaces, safe, stable and continuous operation is ensured, and the system is suitable for industrial and electronic-grade high-purity oxygen production requirements.

Description

Technical Field

[0001] This invention relates to the field of methane removal and oxygen purification technology, and in particular to a methane removal and oxygen purification system and method. Background Technology

[0002] Traditional technologies typically employ methods such as cryogenic separation, room temperature adsorption, and high-temperature catalytic oxidation, which have many problems such as high energy consumption, limited purification depth, and complex systems. These problems lead to high operating costs, difficult maintenance, and difficulty in meeting the 9N-level ultra-high purity requirements for product gas.

[0003] An existing patent application (application number 202411959949.4) describes a purification system for oxygen, nitrogen, and crude neon / helium gas. This system uses a non-cryotherapy gas separation technique to purify nitrogen, oxygen, and crude neon / helium gas in a coordinated manner, achieving multi-component gas synergistic treatment. It employs units such as a deoxygenation tower, a permeate membrane module, a carbon dioxide and water adsorption tower, and an oxygen purification tower to remove hydrocarbons, nitrogen oxides, and perform deep purification of oxygen. However, this system suffers from problems such as overly complex process flow, excessive system coupling, and poor operational flexibility. In this system, nitrogen purification and hydrogen removal from crude neon / helium gas are interdependent and must operate synchronously, preventing independent regeneration or adjustment, leading to difficulties in operation scheduling. The three-stage permeate membrane structure results in high pressure loss, requiring pressurization for waste gas recirculation, significantly increasing energy consumption. The ice dryer's refrigeration path is complex, resulting in low cooling efficiency and inaccurate temperature control. More importantly, this method does not have a dedicated methane removal unit. Methane is difficult to remove effectively under conventional adsorption and catalysis conditions. Even after multi-stage treatment, it is still difficult to reduce the 1000 ppb methane in the feed gas to below 1 ppb, which cannot meet the stringent requirements of high-end electronic manufacturing processes for 9N-grade oxygen.

[0004] An existing patent application (application number 201911037247.X) describes a system and method for producing medical oxygen using a purification tank. This method utilizes a high temperature (above 800°C) within the purification tank to cause a combustion reaction between hydrocarbons and oxygen. The resulting carbon dioxide and moisture are then removed by a purifier. However, this method suffers from extremely high energy consumption, significant safety hazards, and short equipment lifespan. High-temperature combustion in an oxygen-rich environment poses an explosion risk, and the heating device operates under extreme conditions for extended periods, leading to material aging and frequent maintenance. The heat exchange structure is poorly designed, resulting in low heat transfer efficiency and a tendency for localized overheating. This method is extremely ineffective at removing chemically stable methane, as its reactivity is low below 800°C, making complete oxidation difficult, and residual methane concentrations typically remain above 100 ppb. Furthermore, the system lacks deep purification methods for nitrogen, argon, and other trace impurities, failing to achieve a purity target of 9N or higher. It also suffers from low automation, lacks a dynamic feedback mechanism, and is ill-suited to fluctuations in inlet gas quality.

[0005] In summary, existing technologies cannot provide an effective solution for the deep removal of high-concentration methane (1000ppb) to below 1ppb, especially lacking proprietary technological pathways for the efficient conversion and removal of methane, which poses challenges to the application of ultra-high purity oxygen in high-end fields such as semiconductors and photolithography. Summary of the Invention

[0006] In view of the above problems, the present invention provides a methane removal and oxygen purification system and method to solve the problems of insufficient gas purification quality, low regeneration efficiency and insufficient automation in the prior art.

[0007] To address the problems of existing technologies, the present invention adopts the following technical solution: a methane removal and oxygen purification system, comprising an adsorption system and a control system, characterized in that: the raw material gas inlet is connected to the cold side inlet of a gas-to-gas heat exchanger via a pipeline, the cold side outlet of the gas-to-gas heat exchanger is connected to the gas inlet of a catalytic tank, the catalytic tank being a vertically installed cylindrical pressure vessel with a heating device on its outer wall and a temperature sensor inserted into a temperature measuring sleeve; the gas outlet of the catalytic tank is connected to the hot side inlet of the gas-to-gas heat exchanger via a pipeline, the hot side outlet being connected to the gas inlet of a water-cooled heat exchanger via a pipeline, and the gas outlet leading to the front end of the adsorption system; the adsorption system consists of two structurally identical adsorption tanks, ADS-A and ADS-B, which are connected in parallel. Placed on the same support, each adsorption tank's air inlet is connected to the front end of the main air circuit via an independent pneumatic valve, and then outputs to the purified gas outlet via the same pneumatic valve. A pressure equalization branch is provided between the two adsorption tanks, which consists of a pneumatic valve and a throttling orifice connected in series. The two ends of the pipe are connected to the air inlets of ADS-A and ADS-B, respectively. The regeneration gas route is led out from the purified gas outlet, and after passing through a pressure regulating valve, it is divided into two paths. Each path is connected in series with a throttling orifice, a preheater, and a corresponding pneumatic valve, and finally connected to the bottom air inlets of the two adsorption tanks. The top air outlet of each adsorption tank is cooled by a regeneration heat exchanger and then connected to the regeneration exhaust port. The control system is based on a PLC and connects to temperature, pressure, and flow sensors and pneumatic actuators through I / O modules to achieve logical linkage.

[0008] Preferably, the cooling medium for the regeneration heat exchange is circulating water, and its inlet and outlet water pipes are controlled by solenoid valves, with sampling valves and bypass interfaces installed at key nodes.

[0009] Preferably, the catalyst tank is filled with a honeycomb ceramic support, and the inner wall of its channel is coated with a platinum-palladium bimetallic catalyst layer with a Pt:Pd mass ratio of 3:1 and a catalyst coating thickness of 20-50 μm. Preferably, the gas-to-gas heat exchanger has a coaxial double-tube structure, with the inner tube carrying low-temperature raw material gas and the outer tube carrying high-temperature reaction gas, and the heat exchange length is ≥1.5m, realizing countercurrent heat exchange; Preferably, each adsorption tank is a vertical cylindrical container with three layers of packing support plates arranged from bottom to top inside, which respectively support 5Å molecular sieve, modified silica gel and high silica zeolite particles, with a total bed height ≥500mm; Preferably, the throttling orifice is a standard flow limiting orifice plate with a diameter of Φ0.8mm, installed on the downstream side of AV-13, to limit the pressure equalization rate to within 0.1MPa / min; Preferably, the preheater is an electric heating tube bundle structure with a heating section length ≥300mm, an outlet temperature set at 250℃, and an adjustable heating power range of 1.5~3kW; Preferably, the regenerator HE-2 is a plate heat exchanger with a single-pass gas flow design and a multi-pass cooling water flow design to ensure that the exhaust temperature is ≤40℃. Preferably, the PLC is configured with an analog input module to receive TC14, TC16, and PX1 signals, and a digital output module to drive 12 pneumatic valves from AV-2 to AV-13.

[0010] An oxygen purification process based on the coupling of catalytic oxidation and adsorption regeneration is described in the following steps.

[0011] Step A. After filtering the methane-containing feed oxygen, it is introduced into the catalytic reaction zone, where CH4 reacts with O2 at a temperature of 380–420°C to produce CO2 and H2O. The catalytic reaction is carried out in a fixed-bed reactor. Step B. After the reaction, the high-temperature gas first passes through a gas-to-gas heat exchanger to recover heat, reducing the gas temperature from 400°C to 200°C, and then passes through a water-cooled heat exchanger to further cool it to 30°C. Step C. The cooled gas enters the adsorption chamber in operation, where CO2, H2O, and other hydrocarbon impurities are removed through physical adsorption at room temperature. The adsorption operation pressure is 0.6–0.8 MPa, and the gas residence time in the adsorption bed is ≥3 s to ensure that impurities are fully captured by the multilayer adsorbents, including 5Å molecular sieves, modified silica gel, and high-silica zeolite, thereby obtaining a high-purity oxygen product.

[0012] Step D: After the working adsorption tank has run for a preset time, its inlet and outlet valves are closed, and another adsorption tank is started. The regeneration cycle is triggered using a cumulative running time criterion algorithm. , When R t When rigger≥Tt, initiate the ADS-A or ADS-B regeneration process; Where, Δt i Let I be the time interval for the i-th consecutive run. o This is the running status indication function, where Tt is the preset regeneration cycle threshold. Purified oxygen is introduced into the decommissioned adsorption tank as a regeneration gas source. The regeneration gas flow rate is 20% of the normal operating flow rate. After being heated to 250°C, the oxygen is reversed and introduced into the tank to desorb and regenerate the adsorbent. After heating, continue to purge with purified gas at room temperature for 30 minutes, or terminate early when the outlet temperature change rate is less than 0.5℃ / min, until the tank temperature drops below 40℃. After cold purging, open the pressure equalization valve and use the pressure of the running tank to pressurize and balance the regeneration tank. The pressure equalization control for switching between the two tanks uses a pressure difference feedback function. , If P d If iff > ΔPset, then the pneumatic valve AV-13 is opened and pressure is equalized through the throttle orifice OR-3 for a duration of tb (typically 30 seconds); where P ADSA and P ADSB ΔPset represents the real-time pressure inside the two adsorption tanks, and ΔPset is the maximum allowable pressure difference threshold.

[0013] Preferably, the catalytic reaction is carried out in a fixed-bed reactor with a CH4 conversion rate of ≥99.9%.

[0014] Preferably, the preset time is 8 hours.

[0015] Preferably, the catalytic reaction zone and the regeneration gas heating temperature are controlled by a PID function, and the heating control adopts a PID temperature regulation function, the expression of which is: , Among them, T c trl(t) represents the heating output command value at time t, e(t) = Tset - Tmeas(t), which is the deviation between the set temperature Tset and the measured temperature Tmeas(t); K p For proportional gain, K i For integral gain, K d The differential gain is determined by system calibration.

[0016] This invention employs an integrated purification system combining catalytic oxidation, deep adsorption, and intelligent regeneration, solving the technical challenge of existing technologies being unable to remove methane from 1000 ppb to below 1 ppb. The entire system can achieve a methane content of ≤1 ppb in oxygen (9N grade), meeting the requirements of high-end processes.

[0017] Among them, the catalytic oxidation unit can efficiently convert difficult-to-remove methane into easily adsorbable CO2 and H2O, breaking through the bottleneck of the limited methane purification capacity of conventional adsorption methods; the two-stage heat exchange structure significantly reduces energy consumption and improves system energy efficiency; the pressure equalization branch combined with the throttling orifice effectively suppresses pressure fluctuations, prevents adsorbent pulverization, and extends service life; the closed-loop regeneration gas circuit uses high-purity oxygen as the regeneration gas source, avoiding external pollution and ensuring the purity of the product gas; the multi-algorithm integrated PLC control system realizes precise temperature control, dynamic regeneration judgment and smooth switching, improving system stability and automation level.

[0018] The synergistic effect of the various parts of this invention not only improves methane removal efficiency but also optimizes energy utilization, equipment lifespan, and operational reliability. It solves problems such as insufficient purification depth, high energy consumption, incomplete regeneration, and low automation in existing technologies, providing a practical and feasible technical solution for the preparation of ultra-high purity oxygen. Attached Figure Description

[0019] Figure 1 A schematic diagram of the structure provided by the present invention; Figure 2 This is a control block diagram provided by the present invention. Detailed Implementation

[0020] The exemplary embodiments of this disclosure are described below with reference to the accompanying drawings, including various details of the embodiments to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0021] Reference Figure 1 As shown: The methane-oxygen purification system has its feed gas inlet connected to the cold-side inlet of a gas-to-gas heat exchanger (HE-3) via a pipeline. The cold-side outlet of the gas-to-gas heat exchanger (HE-3) is connected to the inlet of a catalytic converter (CAT). The catalytic converter is a vertically mounted cylindrical pressure vessel with a heating device on its outer wall and a temperature sensor TC14 inserted into a temperature measuring sleeve. The interior of the catalytic converter is filled with a honeycomb ceramic carrier, and the inner wall of its channels is coated with a platinum-palladium bimetallic catalyst layer with a Pt:Pd mass ratio of 3:1 and a catalyst coating thickness of 20–50 μm. This catalyst is used to promote the complete oxidation reaction of methane and oxygen to produce CO2 and H2O under high-temperature conditions.

[0022] The gas outlet of the catalytic converter is connected to the hot-side inlet of the gas-to-gas heat exchanger (HE-3) via a pipeline. The hot-side outlet is then connected to the gas inlet of the water-cooled heat exchanger (HE-4) via another pipeline. The gas outlet of HE-4 leads to the front end of the adsorption system. The gas-to-gas heat exchanger (HE-3) has a coaxial double-tube structure. The inner tube carries the low-temperature feed gas, and the outer tube carries the high-temperature reaction gas. The heat exchange length is ≥1.5m, realizing countercurrent heat exchange and effectively recovering the reaction heat. The water-cooled heat exchanger (HE-4) further cools the gas to the ambient temperature range of 20-30℃, and a temperature sensor TC16 is installed at its outlet to monitor the outlet gas temperature in real time and feed it back to the control system.

[0023] The adsorption system consists of two identical adsorption tanks, ADS-A and ADS-B, arranged in parallel on the same support. Their respective inlets are connected to the main gas path via independent pneumatic valves AV-2 and AV-3, and exit to the purified gas outlet via AV-7 and AV-8. Each adsorption tank is a vertical cylindrical container with three layers of packing support plates arranged from bottom to top, supporting 5Å molecular sieves, modified silica gel, and high-silica zeolite particles, respectively. The total bed height is ≥500mm. It performs efficient physical adsorption of CO2, H2O, and other hydrocarbon impurities at room temperature and operating pressures of 0.6–0.8 MPa.

[0024] A pressure equalization branch is provided between the two adsorption tanks. This branch consists of a pneumatic valve AV-13 and a throttling orifice OR-3 connected in series, with the two ends of the pipe connected to the air inlets of ADS-A and ADS-B, respectively. The throttling orifice OR-3 is a standard flow-limiting orifice plate with a diameter of Φ0.8mm, installed downstream of AV-13, used to limit the pressure equalization rate to within 0.1MPa / min, avoiding equipment shock or adsorbent pulverization caused by sudden pressure changes.

[0025] The regeneration gas route is led out from the purified gas outlet, and after passing through the pressure regulating valve PRV-2, it is divided into two paths. Each path is connected in series with the throttling orifice OR-1, the preheater, and the corresponding pneumatic valve AV-9 or AV-10, and finally connected to the bottom air inlet of ADS-A or ADS-B respectively. The preheater is an electrically heated tube bundle structure with a heating section length ≥300mm, an outlet temperature set at 250℃, and an adjustable heating power range of 1.5~3kW, used to provide the heat energy required for desorption.

[0026] The top outlet of each adsorption tank is cooled by the regeneration heat exchanger HE-2 and then connected to the regeneration exhaust port. The cooling medium of HE-2 is circulating water, and its inlet and return water pipes are controlled by solenoid valves. The regeneration heat exchanger HE-2 is a plate heat exchanger with a single-pass gas flow design and a multi-pass cooling water flow design, ensuring that the exhaust temperature is ≤40℃, meeting safety emission requirements.

[0027] All functional components are connected via 316L stainless steel pipes using compression fittings or flanged detachable joints. The main pipe diameter is DN15~DN25. Welding is performed using fully automatic rail argon arc welding, and the welds are inspected by X-ray flaw detection. Sampling valves and bypass interfaces are installed at key nodes to ensure system sealing and maintainability.

[0028] The control system is centered around a PLC, equipped with analog input modules to receive signals from TC14, TC16, and PX1, and digital output modules to drive 12 pneumatic valves (AV-2 to AV-13), enabling real-time monitoring and logical linkage control of parameters such as temperature, pressure, and flow. The control system incorporates data acquisition, logic judgment, and execution control modules. Based on the real-time collected temperature, pressure, and flow parameters, it uses embedded algorithms to dynamically adjust the valve opening and closing sequence, heating power output, and regeneration cycle start conditions.

[0029] An oxygen purification process based on the coupling of catalytic oxidation and adsorption regeneration is described in the following steps.

[0030] After filtering, the methane-containing feedstock oxygen is introduced into the catalytic reaction zone, where CH4 reacts with O2 at a temperature of 380–420 °C to produce CO2 and H2O. The catalytic reaction is carried out in a fixed-bed reactor with a space velocity (SV) of 1500 h⁻¹. -1 The CH4 conversion rate is ≥99.9%. During the reaction, methane is completely oxidized under the action of rare metal catalysts supported on platinum or palladium to generate harmless products, thereby achieving deep removal.

[0031] After the reaction, the high-temperature gas first recovers heat through a gas-to-gas heat exchanger, reducing the gas temperature from 400℃ to 200℃ (HE-3), and then cools it to 30℃ through a water-cooled heat exchanger (HE-4), with a total heat recovery efficiency of ≥70%. This heat exchange process not only reduces the inlet temperature of the subsequent adsorption system, but also significantly improves the overall energy efficiency of the system.

[0032] The cooled gas enters the adsorption chamber in operation, where CO2, H2O, and other hydrocarbon impurities are removed through physical adsorption at room temperature. The adsorption operation pressure is 0.6–0.8 MPa, and the gas residence time in the adsorption bed is ≥3 s to ensure that impurities are fully captured by multilayer adsorbents such as 5Å molecular sieves, modified silica gel, and high-silica zeolite, thereby obtaining a high-purity oxygen product.

[0033] After the working adsorption tank has run for a preset time (e.g., 8 hours), its inlet and outlet valves are closed, and another adsorption tank is started. The regeneration cycle triggering condition uses a cumulative running time criterion algorithm: ,

[0034] When R tWhen rigger ≥ Tt, initiate the regeneration process of ADS-A or ADS-B; where Δt i Let I be the time interval (in hours) for the i-th consecutive run. o This is the operating status indicator function (1 when the adsorption tank is running, 0 when the adsorption tank is stopped), and Tt is the preset regeneration cycle threshold (typically 72 hours). This algorithm is deployed in the timing module of the control system to determine whether to enter the regeneration program.

[0035] Purified oxygen is introduced into the deactivated adsorption tank as a regeneration gas source. The regeneration gas flow rate is 20% of the normal operating flow rate. After being heated to 250°C, it is introduced into the tank in reverse to desorb and regenerate the adsorbent.

[0036] During the heating process of the catalytic converter and the regeneration heating stage of the adsorption tank, the heating temperature is controlled by a PID algorithm with a deviation of ≤±2℃. The heating control employs a PID temperature regulation algorithm, the expression of which is:

[0037] Among them, T c trl(t) represents the heating output command value at time t (unit: % power), e(t) = Tset - Tmeas(t), which is the deviation between the set temperature Tset and the measured temperature Tmeas(t); K p For proportional gain, K i For integral gain, K d The differential gain is determined by system calibration. Ensure the temperature remains stable within ±2℃ of the target range.

[0038] After heating is completed, continue to purge with purified gas at room temperature for cold blowing. The cold blowing stage lasts for 30 minutes, or is terminated early when the outlet temperature change rate is less than 0.5℃ / min, until the barrel temperature drops below 40℃.

[0039] After cold blowing is completed, the pressure equalization valve is opened, and the pressure of the running tank is used to pressurize and balance the regeneration completed tank. The dual-tank switching pressure equalization control adopts a pressure difference feedback algorithm.

[0040] If P d If iff > ΔPset, then the pneumatic valve AV-13 is opened and pressure is equalized through the throttle orifice OR-3 for a duration of tb (typically 30 seconds); where P ADSA and P ADSB These represent the real-time pressures (in MPa) inside the two adsorption tanks, and ΔPset is the maximum allowable pressure difference threshold (typically 0.05 MPa). This algorithm is executed before switching adsorption tanks to avoid airflow impact caused by excessive pressure difference.

[0041] After pressure equalization, the original working tank is switched to standby mode, and the original regeneration tank is switched to working mode, completing one cycle switchover. A safety confirmation procedure is performed before and after each switchover, including checking whether the non-working tank is sealed, whether valves are leak-free, and whether the system has any alarms, ensuring continuous and stable process operation. The entire process is automatically executed by a PLC control system, covering functions such as valve opening and closing sequence, timing control, temperature and pressure interlock protection, and fault alarms, achieving fully automated management of the entire process.

[0042] I. Application Examples and Comparative Analysis To verify the actual operating effect of the oxygen purification system and process, two typical operating conditions were selected for actual testing, representing conventional industrial oxygen use scenarios and high-purity electronic-grade gas supply requirements, respectively. The operating parameters and performance of the two specific application examples are as follows.

[0043] Application Example 1: Preparation of high-purity oxygen for industrial welding.

[0044] Case study of a large metal processing workshop. The raw gas is oxygen-enriched gas from an air separation unit, containing approximately 500 ppmv of methane and other trace hydrocarbons. It needs to be deeply purified before being used in the automated laser welding production line, requiring high purity and stability of oxygen.

[0045]

[0046] The final product gas test results are as follows: CH4 ≤ 0.5 ppmv; H2O ≤ 1 ppmv; CO2 ≤ 0.3 ppmv; total hydrocarbon impurities ≤ 1 ppmv (calculated as CH4); oxygen purity ≥ 99.999%. The system has been running continuously and stably for more than 6 months without any shutdown events caused by adsorbent failure or catalyst deactivation.

[0047] Application Example 2: Supply of ultra-high purity oxygen for semiconductor manufacturing.

[0048] This case study serves an integrated circuit wafer fab. The raw material gas comes from the on-site PSA oxygen generator unit. The initial methane content fluctuates greatly (300-800 ppmv) and is extremely sensitive to impurities such as water and carbon dioxide. It needs to meet the Class F or higher requirements of the SEMI standard.

[0049]

[0050] Actual measured data of product gas: CH4 ≤ 0.2 ppmv; H2O ≤ 0.5 ppmv; CO2 ≤ 0.1 ppmv; particulate matter (≥0.1μm) < 1 particle / L; oxygen purity ≥ 99.9995%.

[0051] It meets the electronic special gas delivery standards, has been successfully connected to the plant's bulk gas pipeline network, and has been operating for a long time without any alarm records.

[0052] Advantages and Effects Analysis and Comparative Summary The actual operational data from the two application scenarios above demonstrate that this coupled catalytic oxidation and adsorption-regeneration system exhibits excellent adaptability and stability under varying degrees of complexity. The following comparison summarizes its core advantages from the perspective of key technical indicators.

[0053] 1. Highly efficient methane removal capability: In both operating conditions, the initial CH4 concentrations were 500 ppmv and up to 800 ppmv, respectively. After catalytic oxidation and multi-stage adsorption treatment, the final residual amount was less than 1 ppmv, with a CH4 conversion rate of ≥99.9%, which fully meets the stringent limits for hydrocarbon impurities in high-end industries and electronics.

[0054] 2. Significant energy-saving and consumption-reducing characteristics: The system employs a gas-to-gas heat exchanger (HE-3) to achieve counter-current heat exchange, recovering heat from the high-temperature reaction gas and reducing its temperature from approximately 400°C to 200°C. The gas is then further cooled to 30°C by a water-cooled heat exchanger. The measured heat recovery efficiency reaches 72.3%, significantly reducing the subsequent cooling load and saving approximately 35% of electricity compared to traditional all-water cooling solutions.

[0055] 3. Multi-layered composite adsorption structure enhances purification depth: A 5Å molecular sieve is used to preferentially capture CO2 and small water molecules, a modified silica gel layer in the middle layer enhances moisture absorption, and a high-silica zeolite layer adsorbs residual hydrocarbons, forming a gradient purification path. This regeneration design avoids the overload problem of a single adsorbent, essentially achieving the same lifespan as the unit.

[0056] 4. Intelligent control system ensures continuous operation PLC system integration time accumulation criterion R t rigger and differential pressure feedback algorithm P d The iff algorithm enables precise triggering and safe pressure equalization control of the regeneration process. The PID temperature control algorithm ensures that the heating process deviation is ≤±2℃, effectively preventing local overheating from causing adsorbent structural damage or catalyst sintering.

[0057] 5. Compact and highly reliable design All piping is made of 316L stainless steel, and welded parts are inspected by X-ray flaw detection. The system leakage rate is <1×10⁻⁶. -9 Pa·m 3 / s (helium leak detection standard) meets high sealing requirements. The compression fitting and flange connection facilitates maintenance and disassembly, and bypass interfaces are configured at key points to support online maintenance.

[0058] In summary, this oxygen purification system not only achieves highly efficient removal of impurities such as methane, but also demonstrates significant technological advantages over traditional purification processes in terms of energy efficiency, stability, and safety through energy recovery, intelligent control, and modular design. It is applicable to a wide range of fields, from general industry to high-end electronics manufacturing. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A methane removal and oxygen purification system, comprising a catalytic tank, characterized in that: The raw material gas inlet is connected to the cold side inlet of the gas-gas heat exchanger via a pipeline. The cold side outlet of the gas-gas heat exchanger is connected to the gas inlet of the catalytic tank. The catalytic tank is a vertically installed cylindrical pressure vessel with a heating device on its outer wall and a temperature sensor inserted into a temperature measuring sleeve. The gas outlet of the catalytic tank is connected to the hot side inlet of the gas-gas heat exchanger via a pipeline. The hot side outlet is then connected to the gas inlet of the water-cooled heat exchanger via a pipeline. The gas outlet of the water-cooled heat exchanger leads to the front end of the adsorption system. The adsorption system consists of two identical adsorption tanks, ADS-A and ADS-B, arranged in parallel on the same support. Each tank's inlet is connected to the main gas path via an independent pneumatic valve, and then exits to the purified gas outlet via the same pneumatic valve. A pressure equalization branch is provided between the two adsorption tanks, consisting of a pneumatic valve and a throttling orifice connected in series, with both ends of the pipe connected to the inlets of ADS-A and ADS-B, respectively. The regeneration gas route is led out from the purified gas outlet, and after passing through a pressure regulating valve, it is divided into two paths. Each path is connected in series with a throttling orifice, a preheater, and a corresponding pneumatic valve, ultimately connecting to the bottom inlets of the two adsorption tanks. The top outlets of each adsorption tank are cooled by a regeneration heat exchanger and then connected to the regeneration exhaust port. The control system is based on a PLC, connecting temperature, pressure, and flow sensors and pneumatic actuators via I / O modules to achieve logical linkage.

2. The methane removal and oxygen purification system according to claim 1, characterized in that: The cooling medium for the regenerative heat exchange is circulating water, and its inlet and outlet water pipes are controlled by solenoid valves. Sampling valves and bypass interfaces are set at key nodes.

3. The methane removal and oxygen purification system according to claim 1, characterized in that: The catalytic tank is filled with a honeycomb ceramic carrier, and the inner wall of its channel is coated with a platinum-palladium bimetallic catalyst layer with a Pt:Pd mass ratio of 3:1 and a catalyst coating thickness of 20-50 μm.

4. The methane removal and oxygen purification system according to claim 1, characterized in that: The gas-to-gas heat exchanger has a coaxial double-tube structure, with the inner tube carrying low-temperature raw material gas and the outer tube carrying high-temperature reaction gas. The heat exchange length is ≥1.5m, realizing countercurrent heat exchange.

5. The methane removal and oxygen purification system according to claim 1, characterized in that: Each adsorption chamber is a vertical cylindrical container with three layers of packing support plates arranged from bottom to top inside, respectively supporting 5Å molecular sieves, modified silica gel and high silica zeolite particles, with a total bed height ≥500mm.

6. The methane removal and oxygen purification system according to claim 1, characterized in that: The regenerator HE-2 is a plate heat exchanger.

7. The purification method of any one of the systems described in claims 1-6, characterized in that: Step A. After filtering the methane-containing feed oxygen, it is introduced into the catalytic reaction zone, where CH4 reacts with O2 at a temperature of 380–420°C to produce CO2 and H2O. The catalytic reaction is carried out in a fixed-bed reactor. Step B. After the reaction, the high-temperature gas first passes through a gas-to-gas heat exchanger to recover heat, reducing the gas temperature from 400°C to 200°C, and then passes through a water-cooled heat exchanger to further cool it to 30°C. Step C. The cooled gas enters the adsorption chamber in operation, where CO2, H2O, and other hydrocarbon impurities are removed through physical adsorption at room temperature. The adsorption operation pressure is 0.6–0.8 MPa, and the gas residence time in the adsorption bed is ≥3 s to ensure that impurities are fully captured by the multilayer adsorbents, including 5Å molecular sieves, modified silica gel, and high-silica zeolite, thereby obtaining a high-purity oxygen product.

8. The oxygen purification process based on the coupling of catalytic oxidation and adsorption regeneration according to claim 7, characterized in that: It also includes step D: After the working adsorption tank has run for a preset time, its inlet and outlet valves are closed, and another adsorption tank is started. The regeneration cycle triggering condition adopts the cumulative running time criterion algorithm. ， When R t When rigger ≥ Tt, initiate the ADS-A or ADS-B regeneration process; Where, Δt i Let I be the time interval for the i-th consecutive run. o This is the running status indication function, where Tt is the preset regeneration cycle threshold. Purified oxygen is introduced into the decommissioned adsorption tank as a regeneration gas source. The regeneration gas flow rate is 20% of the normal operating flow rate. After being heated to 250°C, the oxygen is reversed and introduced into the tank to desorb and regenerate the adsorbent. After heating, continue to purge with purified gas at room temperature for 30 minutes, or terminate early when the outlet temperature change rate is less than 0.5℃ / min, until the tank temperature drops below 40℃. After cold purging, open the pressure equalization valve and use the pressure of the running tank to pressurize and balance the regeneration tank. The pressure equalization control for switching between the two tanks uses a pressure difference feedback function. ， If P d If iff > ΔPset, then the pneumatic valve AV-13 is opened and pressure is equalized through the throttle orifice OR-3 for a duration of tb (typically 30 seconds); where P ADSA and P ADSB ΔPset represents the real-time pressure inside the two adsorption tanks, and ΔPset is the maximum allowable pressure difference threshold.

9. The oxygen purification process based on the coupling of catalytic oxidation and adsorption regeneration according to claim 8, characterized in that: The preset time is 8 hours.

10. The oxygen purification process based on the coupling of catalytic oxidation and adsorption regeneration according to claim 7 or 8, characterized in that: The catalytic reaction zone and regeneration gas heating temperature are controlled by a PID function. The heating control uses a PID temperature regulation function, the expression of which is: ， Among them, T c trl(t) represents the heating output command value at time t, e(t) = Tset - Tmeas(t), which is the deviation between the set temperature Tset and the measured temperature Tmeas(t); K p For proportional gain, K i For integral gain, K d The differential gain is determined by system calibration.

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