Hydrogen purification system based on adsorption and membrane separation cooperation

Abstract

This invention specifically relates to a hydrogen purification system based on the synergistic application of adsorption and membrane separation, encompassing the field of hydrogen purification technology. The system includes: a feed gas pretreatment module; a pressure swing adsorption (PSA) primary purification module; a membrane separation deep purification module; a truncation gas pulse regeneration control module; and a tail gas recovery and energy allocation module. In this invention, the deep synergy between the two core units, PSA and membrane separation, achieves a dual improvement in hydrogen purification accuracy and system operational stability. The design of the radial flow adsorption tower combined with a gradient composite adsorbent bed optimizes the gas flow field distribution and mass transfer efficiency, enabling the cascaded and targeted removal of different types of impurities in the feed gas, ensuring stable and efficient operation of the primary purification stage. The optimized design of the asymmetric composite palladium-silver alloy membrane tube balances hydrogen permeation flux and long-term operational reliability, achieving deep removal of trace toxic impurities from hydrogen and stably producing ultra-high purity hydrogen suitable for high-end hydrogen applications.

Description

Technical Field

[0001] This invention relates to the field of hydrogen purification technology, and in particular to a hydrogen purification system based on the synergy of adsorption and membrane separation. Background Technology

[0002] Hydrogen purification is a key link in the hydrogen energy industry chain, and its technological level directly determines the safety and economy of hydrogen used in the end. At present, the mainstream purification technologies used in the industry are pressure swing adsorption and membrane separation. Both technologies have formed mature industrial application systems and have been widely promoted in different raw gas conditions and purification needs.

[0003] Pressure swing adsorption (PSA) technology achieves separation based on the selective adsorption characteristics of adsorbents for different gas molecules. It features a wide range of adaptable feed gases, high operational flexibility, and strong operational stability. Through adsorbent selection and bed structure optimization, it can achieve efficient removal of multi-component impurities from hydrogen and is one of the mainstream technologies for industrial hydrogen purification. Membrane separation technology achieves selective separation based on the dissolution-diffusion characteristics of gas molecules in dense membrane materials. It boasts advantages such as high separation precision, continuous operation, and no moving parts wear. Palladium-based alloy membrane materials, in particular, with their ultra-high selectivity for hydrogen, can achieve deep removal of impurities at the ppb level, giving them a significant technological advantage in the production of ultra-high purity hydrogen. Currently, the industry has gradually developed a coupled purification process combining pressure swing adsorption (PSA) and membrane separation, leveraging the advantages of both technologies to achieve cascaded purification of hydrogen, providing a mature and feasible technical path for high-end hydrogen applications.

[0004] With the rapid development of the hydrogen energy industry, the industry has put forward higher requirements for the hydrogen recovery rate, comprehensive energy consumption, and long-term operational stability of hydrogen purification systems. There is still room for further optimization and upgrading of existing coupling processes, especially in the deep synergy of material flow and energy flow in the two core separation units, the efficient utilization of resources in the adsorbent regeneration process, and the cascade recovery of waste heat and pressure throughout the entire process. There is still great potential for technological improvement in these areas.

[0005] Based on this, developing a hydrogen purification system that can achieve deep synergy between pressure swing adsorption and membrane separation throughout the entire process and fully and efficiently utilize resources and energy is of great engineering application value and industrial significance for promoting the improvement and cost reduction of ultra-high purity hydrogen preparation technology and helping the hydrogen energy industry chain to achieve large-scale and high-quality development. Summary of the Invention

[0006] The purpose of this invention is to propose a hydrogen purification system based on the synergy of adsorption and membrane separation in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A hydrogen purification system based on the synergistic effect of adsorption and membrane separation includes: The feed gas pretreatment module is used to receive the raw gas, and then pass it through a cyclone gas-liquid separation unit, a wire mesh defoaming filter unit, and a constant temperature heating and regulating unit to remove droplets and dust, and regulate the gas temperature. The pressure swing adsorption primary purification module is used to receive the pretreated gas, remove impurities, and output primary pure hydrogen. The membrane separation deep purification module is used to receive primary pure hydrogen, output ultra-high purity hydrogen product in the tube side, and output high-pressure intercept gas in the shell side. The intercepted gas pulse regeneration control module is used to convert high-pressure intercepted gas into high-frequency pulsed gas flow and inject it in reverse into the radial flow adsorption tower in the regeneration state to remove impurities. The exhaust gas recovery and energy distribution module is used to receive the desorption exhaust gas, recover pressure energy through a turbine expander and output low-temperature exhaust gas to cool the adsorption tower, and convert the exhaust gas into heat energy through a catalytic combustion reactor to heat the membrane separation deep purification module and the feed gas pretreatment module.

[0008] Preferably, the cyclone gas-liquid separation unit includes a cylindrical shell and a liquid collecting cone, and the raw material gas enters the cylindrical shell through a tangential inlet pipe to form an outer vortex; Determination of the critical separation particle size of the cyclone gas-liquid separation unit: ; in, The dynamic viscosity of the raw gas; The width of the rectangular inlet of the cyclone gas-liquid separation unit; The effective number of rotations of the airflow within the cyclone gas-liquid separation unit; The linear velocity of the raw gas at the inlet; The density of the droplet or solid particle; This represents the density of the raw gas.

[0009] Preferably, the wire mesh defoaming filter unit is composed of multiple layers of interwoven micro-wire mesh pads with a hydrophobic and oleophobic coating on the surface; The constant temperature heat tracing and regulating unit adopts a shell-and-tube heat exchange structure, with the raw material gas introduced into the tube side and the heating medium introduced into the shell side; The heat transfer rate of the constant temperature heat tracing unit is through Sure; in, The overall heat transfer coefficient; This refers to the effective heat transfer area of ​​the heat exchanger tube; The temperature difference is the logarithmic mean.

[0010] Preferably, the pressure swing adsorption primary purification module includes multiple radial flow adsorption towers connected in parallel, and the radial flow adsorption towers have a built-in gradient composite adsorbent bed. The radial flow adsorption tower includes an outer shell, an outer gas distribution cylinder, and an inner gas collection cylinder, with a gradient composite adsorbent bed filling the space between the outer gas distribution cylinder and the inner gas collection cylinder. The gradient composite adsorbent bed is divided into three gradient layers from the outside to the inside along the radial flow direction of the airflow: the outermost layer filled with activated alumina particles, the middle layer filled with modified coal-based activated carbon, and the innermost layer filled with low silica-alumina ratio zeolite molecular sieves.

[0011] Preferably, the equilibrium adsorption capacity of the multi-component competitive adsorption in the gradient composite adsorbent bed is determined based on: ; in, Components The amount of saturated monolayer adsorption; Components The adsorption affinity constant; Components Partial pressure in the gas phase; Components The adsorption heterogeneity index; This represents the total number of adsorbable components in the gas mixture. For summation index, it represents each component in the gas mixture.

[0012] Preferably, the membrane separation deep purification module is equipped with a composite palladium-silver alloy membrane tube: The composite palladium-silver alloy membrane tube adopts an asymmetric composite structure, including a porous alumina ceramic tube support layer, a mesoporous transition layer, and a dense palladium-silver alloy thin film separation layer. The shell side of the membrane separation deep purification module is equipped with multi-stage spiral baffles, which force the airflow to laterally sweep the surface of the composite palladium-silver alloy membrane tube in a spiral shape to suppress concentration polarization.

[0013] Preferably, the hydrogen permeation flux of the composite palladium-silver alloy membrane tube is: ; in, The pre-exponential factor for membrane materials; The apparent activation energy is the diffusion energy of hydrogen atoms in the palladium-silver alloy lattice. It is the ideal gas constant; This refers to the absolute operating temperature of the membrane module. The thickness of the dense palladium-silver alloy thin film separation layer; This represents the partial pressure of hydrogen in the shell side; This represents the partial pressure of hydrogen gas in the tube side; This is a stress index.

[0014] Preferably, the intercepted gas pulse regeneration control module is equipped with a fluid jet oscillator: The fluid jet oscillator internally includes a converging nozzle, a wedge-shaped flow divider, a feedback channel, and an attached sidewall; The oscillation frequency of the high-frequency pulsed airflow is constant: ;in, These are Strauhal numbers; To trap the jet velocity of the gas at the constricting nozzle; This is the equivalent diameter of the shrink nozzle.

[0015] Preferably, when the high-frequency pulsed gas flow is injected in reverse into the radial flow adsorption tower in the regeneration state, an alternating local pressure gradient and transient shear force are generated outside the micropores of the adsorbent, and the desorption rate of impurities is: ;

[0016] in, The time variable is the desorption and regeneration process; The total mass transfer coefficient under steady-state conditions; The impulse enhancement response coefficient; The pressure amplitude of the pulsed airflow; The frequency of the pulsed airflow; For the components under the current transient gas phase partial pressure Theoretical equilibrium adsorption amount; Components The actual average adsorption amount.

[0017] Preferably, the exhaust gas recovery and energy distribution module further includes a rigid buffer tank with a back pressure regulating valve, wherein the desorbed exhaust gas first enters the rigid buffer tank for pressure stabilization before entering the turbine expander. The catalytic combustion reactor is filled with a honeycomb ceramic catalyst loaded with precious metals. The high-temperature flue gas generated by the catalytic combustion reactor enters the heating jacket of the membrane separation deep purification module, the shell side of the constant temperature heat tracing and regulating unit, and the air preheater in sequence to realize the cascade utilization of thermal energy. The actual shaft power output of the turbine expander is: ;in, The exhaust gas mass flow rate entering the turbine expander; The specific heat capacity at constant pressure of the mixed exhaust gas; The absolute temperature of the exhaust gas when it enters the turbine expander; The isentropic efficiency of the turbine expander; This refers to the absolute pressure at the inlet of the turbine expander. This refers to the absolute pressure at the outlet of the turbine expander. It represents the adiabatic index of the mixed exhaust gas.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention achieves a dual improvement in hydrogen purification accuracy and system operational stability through the deep synergy of two core units: pressure swing adsorption and membrane separation. The radial flow adsorption tower combined with a gradient composite adsorbent bed optimizes the gas flow field distribution and mass transfer efficiency, enabling the cascaded and directional removal of different types of impurities in the feed gas, ensuring stable and efficient operation of the primary purification stage. The optimized design of the asymmetric composite palladium-silver alloy membrane tube balances hydrogen permeation flux and long-term operational reliability, enabling the deep removal of trace toxic impurities in hydrogen and stably producing ultra-high purity hydrogen suitable for high-end hydrogen application scenarios.

[0019] 2. This invention achieves a significant improvement in overall system energy efficiency and a substantial reduction in operating costs through the resource utilization of waste pressure, waste heat, and waste materials throughout the entire process. The design of the exhaust gas recovery and energy allocation module enables full energy recovery from the pressure swing adsorption (PSA) desorption exhaust gas. The pressure energy of the exhaust gas is recovered and converted into electrical energy through a turbine expander, while the cooling generated during the expansion process optimizes the adsorption conditions, further improving adsorption separation efficiency. Furthermore, the chemical energy in the exhaust gas is recovered through catalytic combustion and supplied to the entire process's heat demand in tiered temperature stages, reducing the system's dependence on external energy input. Attached Figure Description

[0020] Further details, features, and advantages of this application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a system structure diagram of the present invention. Detailed Implementation

[0021] Several embodiments of this application will now be described in more detail with reference to the accompanying drawings to enable those skilled in the art to implement this application. This application may be embodied in many different forms and for various purposes and should not be limited to the embodiments set forth herein. These embodiments are provided to make this application thorough and complete, and to fully convey the scope of this application to those skilled in the art. The embodiments described do not limit this application.

[0022] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0023] Example 1

[0024] Its specific implementation method is combined with the appendix Figure 1 Please provide a detailed explanation.

[0025] Appendix Figure 1 The diagram shows the structural block diagram of a hydrogen purification system based on the synergy of adsorption and membrane separation provided in the embodiments of the present invention. It illustrates the connection relationship between the feed gas pretreatment module and the tail gas recovery and energy allocation module, and marks the main functional interaction flow of each module.

[0026] In this embodiment, it includes: Module 1: Feed gas pretreatment module, used to receive raw gas, and sequentially pass it through a cyclone gas-liquid separation unit, a wire mesh defoaming filter unit, and a constant temperature heating and regulating unit to remove droplets and dust, and regulate the gas temperature; The feed gas pretreatment module is the first solid line of defense to ensure the lifespan of the downstream adsorbent and the permeation performance of the membrane material. If droplets and dust entrained in the feed gas directly enter the adsorption tower, they will clog the micropores of the adsorbent, leading to irreversible decay of the adsorption capacity. This module contains, in sequence, a cyclone gas-liquid separation unit, a wire mesh demister filter unit, and a constant temperature heating and regulation unit.

[0027] The main body of the cyclone gas-liquid separator is made of 316L stainless steel to resist corrosion from trace amounts of hydrogen sulfide that may be present in the feed gas. Its structure includes a cylindrical upper shell and an inverted conical lower liquid collection hopper. The feed gas enters the cylindrical shell at a high speed of 15 to 25 m / s through a tangential inlet pipe. The tangentially entering airflow is confined within the shell and forced into a downward spiral motion, forming a strong external vortex flow field.

[0028] Under strong centrifugal force, liquid water droplets, heavy hydrocarbon droplets, and large solid dust particles with densities much greater than gases are thrown towards the inner wall of the cylinder. Upon collision with the inner wall, these particles dissipate a significant amount of kinetic energy and, subsequently, under the combined influence of gravity and downward airflow, spiral down the wall into the collection cone at the bottom. The bottom of the collection cone is equipped with a high-precision ultrasonic level gauge and an automatic drain valve. When the liquid level reaches the set upper limit, the drain valve automatically opens, discharging the collected waste liquid from the system.

[0029] To ensure separation efficiency, the critical separation particle size (i.e., the smallest particle diameter that can be completely separated) of the cyclone gas-liquid separation unit is determined by the following formula: ; in, Critical separation particle size, in meters (m); the smaller this value, the stronger the dust removal and drip removal capability of the separator. The dynamic viscosity of the feed gas, measured in Pascal-seconds (Pa·s). This parameter fluctuates dynamically with changes in gas temperature and composition. : Width of the rectangular inlet of the cyclone separator, in meters (m); : The effective number of rotations of the airflow within the cyclone separator. A dimensionless parameter, typically ranging from 5 to 10, depending on the ratio of the height to the diameter of the cylinder. Linear velocity of the raw gas at the inlet, in meters per second (m / s); Density of droplets or solid particles, expressed in kilograms per cubic meter; : Density of the raw gas, in kilograms per cubic meter; The system monitors and adjusts the inlet linear velocity in real time by installing a Venturi flow meter and a variable frequency control valve on the inlet pipe. This allows for control of the critical separation particle size, ensuring that droplets and particles with a diameter greater than 5 micrometers are effectively removed.

[0030] After being separated by the cyclone separator, the gas folds back upward above the cone, forming an inner vortex, and then enters the wire mesh defoaming filter unit located at the top of the housing. This unit is designed to capture fine mist droplets (between 1 and 5 micrometers in diameter) that the cyclone separator cannot remove.

[0031] The wire mesh defogging filter unit consists of multiple layers of interwoven stainless steel microwire mesh. To enhance the repulsion of water and hydrocarbon droplets, the surface of the microwires is treated with a hydrophobic and oleophobic polytetrafluoroethylene (PTFE) nano-coating. When gas carrying fine mist passes through the mesh at a set apparent flow rate (typically 2 to 4 m / s), the mist deviates from the airflow streamline due to the inertia of the airflow, colliding with the mesh skeleton and adhering to its surface. As the adhering mist accumulates, the tiny droplets coalesce into larger droplets at the intersections of the mesh. When the weight of the droplet exceeds the upward drag of the airflow and the surface tension of the liquid, the droplet drips from the bottom of the mesh and falls back into the collection cone below.

[0032] The pressure drop of gas passing through the wire mesh demister filter unit is a key indicator for system energy consumption control; an excessively high pressure drop indicates potential wire mesh blockage. The pressure drop calculation follows a modified Ergun equation: ; in, Pressure drop of the wire mesh filter unit, in Pascals (Pa). Dynamic viscosity of a gas, measured in Pascal-seconds (Pa·s). Thickness of the wire mesh mat, in meters (m). The porosity of wire mesh pads is a dimensionless parameter, typically between 0.90 and 0.98. High porosity helps reduce pressure drop. Equivalent diameter of wire mesh microfilaments, in meters (m). Apparent velocity of gas passing through the wire mesh, measured in meters per second (m / s). Density of a gas, expressed in kilograms per cubic meter; The system has high-precision pressure transmitters installed on both the upper and lower sides of the wire mesh pad to calculate the pressure difference in real time. When the differential pressure exceeds the set threshold (e.g., 500 Pascals), the control system will issue an alarm, indicating that the wire mesh may be clogged with particulate matter and that an online backflushing cleaning program needs to be initiated.

[0033] The feed gas, after undergoing deep gas-liquid separation, then enters the constant temperature heating and regulating unit. This unit employs a highly efficient shell-and-tube heat exchange structure, with the feed gas flowing through the tubes and the heating medium (such as medium-temperature flue gas or low-pressure steam from the exhaust gas recovery module) flowing through the shell. Multiple arc-shaped baffles are installed inside the shell to increase the turbulence of the heating medium and improve heat transfer efficiency.

[0034] The primary objective of this unit is to raise the temperature of the feed gas to at least 15 degrees Celsius above its water dew point and hydrocarbon dew point. This step is crucial because the gas will experience periodic pressure fluctuations as it subsequently enters the pressure swing adsorption bed. If the gas temperature is close to the dew point during the high-pressure adsorption stage, capillary condensation is highly likely to occur within the micropores of the adsorbent, leading to pore blockage by liquid water or liquid hydrocarbons and severely disrupting the adsorption kinetics.

[0035] The heat transfer rate of the constant temperature heat tracing unit is described by the following fundamental heat transfer equation: ; in, : The total heat transfer rate of the heat exchanger, measured in watts (W). Overall heat transfer coefficient, measured in watts per square kelvin. This coefficient takes into account convective heat transfer inside the tube, heat conduction through the tube wall, and resistance to convective heat transfer outside the tube. Effective heat transfer area of ​​heat exchanger tubes, in square meters; Logarithmic mean temperature difference, in Kelvin (K); Among them, the logarithmic mean temperature difference The calculation formula is: ; in, : Inlet temperature of the heating medium, in Kelvin (K); : Outlet temperature of the heating medium, in Kelvin (K); : Inlet temperature of the raw gas, in Kelvin (K); : The outlet temperature of the raw gas (i.e., the target preheating temperature), in Kelvin (K). The system acquires the gas outlet temperature signal in real time by inserting a high-precision armored thermocouple into the raw gas outlet pipeline, and feeds this signal back to the proportional-integral-derivative (PID) pneumatic control valve at the inlet of the shell-side heating medium. By dynamically adjusting the flow rate of the heating medium, the system controls the raw gas outlet temperature, with fluctuations kept within ±1 degree Celsius.

[0036] Module 2: Pressure Swing Adsorption Primary Purification Module, connected to the feed gas pretreatment module, includes multiple parallel radial flow adsorption towers. The radial flow adsorption towers have built-in gradient composite adsorbent beds to receive the pretreated gas, remove impurities, and output primary pure hydrogen. The pressure swing adsorption (PSA) primary purification module is the core area for achieving the initial separation of hydrogen from a large number of impurities. In order to reduce bed pressure drop, improve mass transfer efficiency, and meet the needs of large-scale industrial production, this module abandons the traditional axial flow adsorption tower design and adopts multiple parallel radial flow adsorption towers, with a carefully designed gradient composite adsorbent bed built in.

[0037] Each radial flow adsorption tower consists of a high-pressure resistant cylindrical shell, an outer gas distribution cylinder, an inner gas collection cylinder, and an annular adsorbent bed filled between the inner and outer cylinders. Both the outer gas distribution cylinder and the inner gas collection cylinder are made of porous sintered metal plates or wedge-shaped wire-wound screens. To ensure uniform radial flow rate of gas throughout the entire tower height and avoid localized short-circuiting of gas flow (i.e., "flow deviation"), the porosity of the inner and outer cylinders is designed with a specific gradient distribution along the axial direction.

[0038] The pretreated feed gas enters from the bottom of the tower, first entering the annular space between the outer shell and the outer gas distribution cylinder. Then, the gas passes radially (i.e., perpendicular to the central axis of the tower) through the adsorbent bed. During this penetration, impurity gas molecules are captured by the active sites on the adsorbent surface, while the highly permeable hydrogen-rich gas collects in the inner gas collection cylinder and finally exits from the outlet at the top of the tower.

[0039] The core hydrodynamic advantage of radial flow design lies in increasing the cross-sectional area of ​​the airflow (the cross-sectional area is equal to the lateral area of ​​the cylinder, much larger than that of axial flow), while significantly shortening the path length of the gas through the bed (the path length is only the width of the annular gap between the inner and outer cylinders). According to Darcy's law for porous media flow, the bed pressure drop is inversely proportional to the cross-sectional area and directly proportional to the path length. Therefore, when processing the same flow rate of gas, the radial flow structure can reduce the bed pressure drop to less than one-fifth of that of a traditional axial flow tower. This extremely low pressure drop characteristic is crucial for maintaining high-pressure driving force in subsequent membrane separation modules, effectively avoiding the need for intermediate booster compressors and saving significant equipment investment and operating energy consumption.

[0040] To address the complex and diverse impurities in the feed gas, a single adsorbent often struggles to remove all impurities simultaneously. Therefore, the adsorbent bed in this module is divided into three functionally distinct gradient layers along the radial flow direction of the gas flow (from the outside to the inside): The outermost layer (windward layer): filled with high specific surface area activated alumina (Al2O3) particles or silica gel. This layer mainly utilizes its abundant hydroxyl functional groups on its surface to preferentially adsorb residual trace moisture and heavy hydrocarbon molecules in the feed gas through strong hydrogen bonding and polar interactions. This layer acts as a "security filter," preventing these highly polar molecules from entering the inner layer and causing irreversible poisoning and deactivation of the microporous adsorbent.

[0041] Intermediate layer (main adsorption layer): Filled with specially chemically modified coal-based activated carbon. The activated carbon possesses an extremely well-developed mesoporous and microporous structure, exhibiting very high adsorption capacity for carbon dioxide (CO2), methane (CH4), and hydrogen sulfide (H2S). By controlling the carbonization and activation process parameters of the activated carbon, its pore size distribution is concentrated between 0.7 and 1.2 nanometers. This pore size range is highly matched with the kinetic diameters of CO2 and CH4, thereby achieving highly efficient physical adsorption based on steric hindrance and van der Waals forces.

[0042] Innermost layer (refined layer): Filled with Li-LSX type (low silica-to-alumina ratio) zeolite molecular sieve. This molecular sieve has undergone deep lithium-ion exchange treatment, and the exposed lithium ions (Li+) on its framework can generate strong induced dipole-quadrupole interactions with carbon monoxide (CO) and nitrogen (N2) molecules. This special chemical-physical composite adsorption mechanism enables the Li-LSX molecular sieve to achieve deep removal of CO and N2 even at extremely low partial pressures, ensuring that the purity of primary hydrogen remains stable at 99.9% to 99.99%.

[0043] In a gradient composite adsorbent bed, multiple impurity gases coexist, and they engage in fierce competitive adsorption in order to compete for limited adsorption sites.

[0044] To predict the equilibrium adsorption capacity of each component under different pressures and temperatures, the system control unit incorporates an extended Langmuir-Freundlich multicomponent competitive adsorption isotherm model: ; in, Components The equilibrium adsorption capacity on the adsorbent, expressed in mol / kg. Components The saturated monolayer adsorption capacity, expressed in mol / kg, represents the limiting adsorption capacity of the adsorbent for that component. Components The adsorption affinity constant, in Pascals. The power of this power decreases exponentially with increasing temperature. Components Partial pressure in the gas phase, measured in Pascals (Pa). Components The adsorption heterogeneity index is a dimensionless parameter that reflects the degree of non-uniformity in energy distribution on the adsorbent surface. When the surface is completely homogeneous, Approaching 1; The total number of adsorbable components in the gas mixture; : Summation index, representing each component in the gas mixture; : Represent the first in the gas mixture The adsorption affinity constant, gas phase partial pressure (unit: Pa), and adsorption heterogeneity index of each component; This model fully considers the competitive effect of different impurity molecules on adsorption sites. For example, when the partial pressure of CO2 in the gas mixture is high, it occupies a large number of adsorption sites due to its large affinity constant, resulting in a significant increase in the denominator and thus affecting the actual adsorption capacity of CH4. The adsorption capacity is far lower than that in the single-component state. The system collects the component concentration of the feed gas in real time using an online gas chromatograph, combines it with pressure sensor data, and substitutes it into the above formula to dynamically calculate the saturation time of the bed, thereby precisely controlling the switching cycle of the adsorption step.

[0045] The process of gas molecules moving from the bulk gas phase through the gas film, into the macropores of the adsorbent, and finally to the adsorption sites within the micropores is an extremely complex dynamic mass transfer process. To accurately describe this process in engineering applications, a linear driving force model is used to characterize the adsorption rate. ; in, Components The rate of change of the average adsorption amount over time, i.e. the adsorption rate, is expressed in mol / (kg·s). : The time variable of the adsorption process, in seconds (s); Components The total mass transfer coefficient, expressed as the reciprocal of seconds. This coefficient integrates external gas film diffusion resistance, macroporous diffusion resistance, and microporous diffusion resistance, and is a core indicator for evaluating the rate of adsorption kinetics. Under the current gas phase partial pressure, the components The theoretical equilibrium adsorption amount (calculated from the above thermodynamic model) is expressed in mol / kg. Components exist The actual average adsorption amount at time t, in moles per kilogram (mol / kg). In actual operation, not all adsorbent in the adsorption tower reaches saturation simultaneously; instead, a "mass transfer zone" of a certain width is formed. At the forefront of this zone, the adsorbent has not yet come into contact with impurities and remains fully active; at the trailing edge, the adsorbent has reached saturation. As the adsorption process continues, the mass transfer zone moves inward toward the inner gas collecting cylinder. When the forefront of the mass transfer zone is about to break through the innermost purification layer, adsorption must be stopped immediately, and the tower switched to regeneration mode.

[0046] To monitor the movement trajectory of the mass transfer zone in real time, this system embeds multiple miniature armored resistance thermometers (RTDs) at different depths (equally spaced radially) within the radial bed. Since adsorption is a typical exothermic reaction, the temperature at the mass transfer zone location rises significantly, forming a distinct temperature peak. The system control unit captures the movement speed and location of this temperature peak within the bed, and, combined with the LDF kinetic model, predicts the adsorption breakthrough time in advance, effectively preventing product gas defects caused by impurity penetration.

[0047] Each adsorption tower undergoes the following complex steps sequentially through precise switching of programmed valves within a complete operating cycle: Adsorption: Under high pressure (typically 1.5 to 2.5 MPa), the feed gas passes radially through the bed, impurities are adsorbed, and primary pure hydrogen is produced.

[0048] Equalization: After adsorption, a large amount of high-pressure hydrogen-rich gas remains in the column. Connecting this column to another column operating at low pressure transfers the high-pressure gas to the low-pressure column, recovering hydrogen and pressure energy. This system is typically configured with multiple equalization steps (e.g., single equalization, double equalization, triple equalization) to maximize hydrogen recovery.

[0049] Forward depressurization: The pressure is further reduced along the adsorption direction, and the released gas is used to flush other towers that are about to complete regeneration.

[0050] Reverse pressure release: Gas is discharged in reverse to the waste gas pipeline network, and the pressure inside the tower drops to near atmospheric pressure, causing some impurities with weak adsorption to begin to desorb.

[0051] Pulse flushing regeneration: The trapped gas pulse flow provided by module four is injected into the bed in the reverse direction (from the inside to the outside) to achieve deep desorption of impurities. This part will be discussed in detail in the subsequent output.

[0052] Equalization: Receives equalization gas from other columns to gradually restore the pressure inside the column.

[0053] Final pressurization of product gas: Using a portion of the primary pure hydrogen product gas, the tower pressure is slowly increased to the adsorption pressure, in preparation for the next cycle.

[0054] Module 3: Membrane separation deep purification module, which is connected to the shell side of the membrane separation deep purification module and the pressure swing adsorption primary purification module respectively. It includes a fluid jet oscillator to convert high-pressure intercepted gas into high-frequency pulsed gas flow and inject it back into the radial flow adsorption tower in the regeneration state to remove impurities.

[0055] After processing by the pressure swing adsorption (PSA) primary purification module, most impurities in the gas have been removed, and the hydrogen purity can typically reach 99.9% to 99.99%. However, for cutting-edge applications such as proton exchange membrane fuel cells (PEMFC) or high-end semiconductor epitaxial wafer manufacturing, the hydrogen purity must reach 99.999% (5N) or even 99.9999% (6N), and the tolerance for trace toxic impurities such as carbon monoxide (CO) and hydrogen sulfide (H2S) is extremely low (usually requiring strict control at the ppb level, i.e., one part per billion). Traditional pressure swing adsorption technology faces significant thermodynamic limitations and economic bottlenecks when dealing with ppb-level impurities.

[0056] Therefore, this system introduces a membrane separation deep purification module based on the principle of selective permeation.

[0057] This module employs a shell-and-tube composite membrane separator with high temperature and high pressure resistance. Its core separation element consists of multiple parallel-connected composite palladium-silver (Pd-Ag) alloy membrane tubes. To balance extremely high hydrogen permeation flux with mechanical strength under harsh operating conditions, the membrane tubes utilize a highly precise asymmetric composite structure design. Porous ceramic support layer: The bottom layer is a high-purity porous α-alumina (α-Al₂O₃) ceramic tube, possessing extremely high mechanical compressive strength and excellent thermal stability. To reduce the flow resistance of gas within the support layer (i.e., Knudsen diffusion resistance), the pore size of the ceramic tube exhibits an asymmetric gradient distribution. The inner side (near the tube side) has a larger pore size, approximately 1 to 3 micrometers; the outer surface undergoes multiple coating processes using an advanced sol-gel method followed by high-temperature sintering to form an extremely thin mesoporous transition layer with a pore size of approximately 5 to 10 nanometers. This transition layer provides an extremely smooth and defect-free substrate for the subsequent deposition of dense metal films.

[0058] Dense Alloy Separation Layer: A dense palladium-silver alloy film with a thickness of only 2 to 5 micrometers is uniformly deposited on the outer surface of the mesoporous transition layer of the ceramic support layer using electroless chemical plating or magnetron sputtering techniques. When pure palladium absorbs hydrogen, it undergoes a crystal phase transition from the α phase (low hydrogen concentration) to the β phase (high hydrogen concentration), resulting in a lattice volume expansion of approximately 10%. After repeated cycles of temperature rise and fall or pressure fluctuations, this phase transition is highly susceptible to fatal "hydrogen embrittlement," leading to microcracks or even peeling and rupture of the film.

[0059] To eliminate this potential hazard, the present invention strictly controls the mass fraction of silver in the alloy to around 23%. The addition of 23% silver not only effectively suppresses the phase transformation from α to β phase and eliminates the risk of hydrogen embrittlement, but also optimizes the lattice constant of the alloy, thereby increasing the diffusion coefficient of hydrogen in the metal lattice and making the overall permeability 1.7 times that of a pure palladium film.

[0060] Primary pure hydrogen enters from the shell side of the membrane module (high-pressure side, typically 1.5 to 2.5 MPa). Driven by the huge partial pressure difference, hydrogen molecules pass through the dense palladium-silver alloy membrane into the tube side (low-pressure side, typically close to atmospheric pressure), becoming ultra-high purity hydrogen. The process of hydrogen passing through the palladium membrane is not a simple physical pore filtration, but follows a complex "dissolution-diffusion" microscopic mechanism, specifically involving the following five tandem physicochemical steps: External diffusion: Hydrogen molecules diffuse from the bulk gas phase in the shell through the gas film boundary layer to the outer surface of the palladium film; Surface dissociative adsorption: Hydrogen molecules undergo chemisorption at the active sites on the outer surface of the palladium film and overcome the dissociation energy to dissociate into two independent hydrogen atoms; Bulk dissolution: The dissociated hydrogen atoms dissolve into the interstitial spaces of the face-centered cubic (FCC) lattice of the palladium-silver alloy; Lattice diffusion: Driven by a concentration gradient (essentially a chemical potential gradient), hydrogen atoms diffuse in a skipping manner through the octahedral interstices of the metal lattice, penetrating the entire film layer to reach the inner surface. Composite desorption and internal diffusion: Hydrogen atoms recombine into hydrogen molecules on the inner surface of the membrane and desorb into the bulk gas phase in the tube side, eventually flowing out of the membrane module.

[0061] Of the five steps described above, the diffusion of hydrogen atoms within the metal lattice (step 4) is typically the rate-controlling step of the entire permeation process. The permeation flux of hydrogen can be described by a modified Richardson equation or Sieferts' law: ; in, Hydrogen permeation flux, expressed in moles per square meter per second; Pre-exponential factor (permeability constant) of membrane materials, expressed in moles per meter-second (Pascals). The power reflects the hydrogen permeability of the material itself; Apparent activation energy of hydrogen atom diffusion in palladium-silver alloy lattice, in joules per mole (J / mol). Ideal gas constant, with a value of 8.314 joules per mole Kelvin; : Absolute operating temperature of the membrane module, in Kelvin (K); The thickness of the dense palladium-silver alloy separation layer, measured in meters (m). A thinner layer results in higher throughput, but a defect-free rate must also be considered. : The partial pressure of hydrogen in the shell side (feed side), in Pascals (Pa). : Partial pressure of hydrogen in the tube side (permeation side), in Pascals (Pa). Stress index; For dense metal films, when bulk diffusion is the absolute controlling step... The theoretical value is 0.5 (i.e., it conforms to Sieverts' law); if the resistance of the surface dissociation or recombination process cannot be ignored (especially under conditions of extremely thin film or low temperature). The value will fluctuate between 0.5 and 1.0.

[0062] The system maintains the operating temperature of the membrane module between 350°C and 400°C using an external high-temperature flue gas jacket or precision electric heating device. Within this temperature range, not only the exponential term... The significantly increased permeation flux meets the requirements for industrial applications. More importantly, the high temperature effectively prevents trace carbon monoxide molecules from generating strong competitive adsorption on the palladium membrane surface, thereby avoiding the "poisoning" and deactivation of the membrane material.

[0063] As hydrogen continuously permeates through the membrane, trace impurities that do not permeate in the shell side (such as nitrogen, methane, and carbon monoxide) accumulate near the outer surface of the membrane. Since these impurity molecules cannot permeate the dense metal membrane, they can only return to the bulk gas phase through reverse molecular diffusion.

[0064] When the impurity flux flowing towards the membrane surface reaches a dynamic equilibrium with the reverse diffusion flux, a fluid boundary layer with a much higher impurity concentration than the bulk gas phase forms on the membrane surface. This phenomenon is known as "concentration polarization" in membrane separation engineering. Concentration polarization causes a sharp drop in the actual hydrogen partial pressure at the membrane surface, which severely weakens the permeation driving force and leads to a significant decrease in the system's hydrogen production.

[0065] To quantify the negative impact of concentration polarization on permeation flux, a thin-film theoretical mass transfer model was introduced into the system: ; in, Hydrogen permeation flux, expressed in moles per square meter per second; The mass transfer coefficient within the gas-phase boundary layer, measured in meters per second (m / s). This coefficient is closely related to the Reynolds number (Re) and Schmidt number (Sc) of the fluid. Total molar concentration of the gas, expressed in moles per cubic meter; : The mole fraction of hydrogen gas at the outer surface of the membrane, dimensionless. In cases of severe concentration polarization, this value is much lower than the bulk concentration; : The mole fraction of hydrogen in the bulk gas phase of the shell side, dimensionless; : Mole fraction of hydrogen on the permeate side of the tube, dimensionless.

[0066] To effectively suppress concentration polarization, this module incorporates a multi-stage helical baffle structure within the shell side. These baffles force the airflow to move beyond simple axial advection within the shell side, instead causing it to helically and at high speed scour the membrane tube surface, increasing the degree of turbulence (significantly raising the Reynolds number). This enhanced turbulence induces intense radial mixing of fluid particles, significantly improving the mass transfer coefficient. This significantly reduces the thickness of the concentration polarization boundary layer. Through this hydrodynamic optimization, the molar fraction of hydrogen at the membrane surface is reduced. Always infinitely close to the main mole fraction This maintains the high separation performance of the membrane module during long-term operation.

[0067] Module 4: Retained Gas Pulse Regeneration Control Module, which is connected to the shell side of the membrane separation deep purification module and the pressure swing adsorption primary purification module respectively. It includes a fluid jet oscillator to convert high-pressure retained gas into high-frequency pulse gas flow and inject it back into the radial flow adsorption tower in the regeneration state to remove impurities. In the membrane separation deep purification module, the gas that does not permeate through the membrane is called "retained gas". This part of the gas is enriched with trace impurities retained from the primary pure hydrogen. At the same time, due to the recovery rate limitation of membrane separation, the retained gas still contains a certain proportion (usually 10% to 20%) of unpermeated hydrogen and maintains a high pressure state similar to that of the feed side (usually between 1.5 and 2.5 MPa).

[0068] In traditional hydrogen purification processes, this retentate gas is usually either depressurized and discharged directly, or fed into a flare system and burned as ordinary fuel. This not only wastes the high-value hydrogen but also squanders valuable pressure energy.

[0069] The regeneration process (i.e. the rinsing step) of traditional pressure swing adsorption requires a large amount of purified product hydrogen to be used for reverse rinsing, resulting in a low overall hydrogen recovery rate and a significant reduction in economic benefits.

[0070] This invention proposes a pulsed regeneration control module for intercepted gas, breaking away from conventional unidirectional material flow designs. This module converts high-pressure intercepted gas into a high-frequency pulsed gas flow, which is then injected in reverse into the pressure swing adsorption tower during the low-pressure regeneration stage. This utilizes the pulsed hydrodynamic effect to achieve deep desorption of the adsorbent. This design not only eliminates the need for external high-purity hydrogen as regeneration gas but also transforms waste gas into a high-value regeneration power source.

[0071] The core component of this module is a pure fluid jet oscillator without any moving mechanical parts, which works in conjunction with the upstream high-pressure buffer tank and high-speed electromagnetic proportional valve. The absence of moving parts gives the device extremely high reliability and a very long service life, enabling it to adapt to harsh operating conditions involving high pressure and frequent switching.

[0072] The high-pressure choke gas first enters the high-pressure buffer tank to smooth out any pressure fluctuations that may occur on the membrane module side, and then enters the fluid jet oscillator through a high-speed electromagnetic proportional valve. The flow channel design inside the oscillator is based on the Coanda Effect (fluid wall adhesion effect) in fluid mechanics.

[0073] Its internal geometry includes a contracting main nozzle, a downstream symmetrical wedge-shaped flow divider, two feedback channels on the left and right, and two sidewalls on the left and right. When the high-pressure intercepted gas is ejected at high speed from the contracting nozzle to form a jet, due to the unavoidable small disturbances in the flow field, the jet will randomly deflect and adhere to a certain sidewall (e.g., the left sidewall).

[0074] At this point, most of the fluid flows out from the left outlet, but a small portion is introduced into the left feedback channel. This feedback fluid flows upstream, generating a lateral pressure pulse at the nozzle outlet, forcing the main jet to detach from the left wall and cross the centerline to attach to the right wall. Subsequently, the right feedback channel activates, pushing the jet back to the left.

[0075] This alternating attachment and switching process occurs continuously within a very short time, thus transforming the continuous steady-state high-pressure airflow into a high-frequency pulsed airflow with periodic pressure peaks and troughs at the oscillator outlet. The oscillation frequency of the pulsed airflow is determined by the Strouhal number, which is calculated using the following formula: ; in, : The oscillation frequency of the pulsed airflow, measured in Hertz (Hz); The Strauhall number is a dimensionless parameter that depends on the internal geometry of the oscillator (such as the length of the feedback channel and the width of the nozzle). In this system, it has been optimized through flow field simulation and is designed to be between 0.015 and 0.035. : The jet velocity of the trapped gas at the converging nozzle, in meters per second (m / s). Equivalent diameter of the constriction nozzle, in meters (m). The system uses a DCS control system to adjust the opening of a high-speed electromagnetic proportional valve, thereby changing the gas flow rate into the oscillator and thus altering the jet velocity. This enables control over the pulse frequency. Precise and stepless control is achieved. Typically, the pulse frequency is controlled between 10 Hz and 50 Hz. This frequency range can match the acoustic resonance characteristics of the adsorbent bed to maximize energy transfer.

[0076] When a high-frequency pulsed gas flow is injected in reverse (from the inner gas collecting cylinder to the outer gas distributing cylinder) into the pressure swing adsorption tower in a low-pressure regeneration state, it exerts a strong stripping effect on impurity molecules on the adsorbent surface. This enhanced desorption mechanism far surpasses traditional steady-state gas flushing, mainly due to the following two deep physical mechanisms: First, the effects of local cavitation and microscopic pressure gradients. When a pulsed gas flow propagates through a porous adsorbent bed, it generates alternating local high-pressure and low-pressure zones. At the pressure trough, the local pressure outside the adsorbent micropores drops sharply, creating a "cavitation effect" similar to that in fluid dynamics. This transient, large pressure gradient increases the driving force for impurity molecules to diffuse from the inside of the micropores outward, disrupting the original adsorption equilibrium. To accurately describe the desorption kinetics under a pulsed flow field, this invention modifies the traditional linear driving force (LDF) model by introducing a pulse enhancement coefficient: ; in, Components The desorption rate (since it is a desorption process, the theoretical equilibrium adsorption amount at this time) Less than the actual adsorption amount Therefore, the rate is negative, representing a decrease in adsorption amount), and the unit is mol / (kg·s).

[0077] : The time variable in the desorption and regeneration process, in seconds; : Total mass transfer coefficient under steady state, in reciprocal of seconds; The pulse-enhanced response coefficient is dimensionless and closely related to the pore structure (micropore ratio) of the adsorbent and the dynamic diameter of gas molecules. Pressure amplitude of pulsed airflow, i.e., the pressure difference between the peak and trough, is measured in Pascals (Pa). : The oscillation frequency of the pulsed airflow, measured in Hertz (Hz); Under the current transient gas phase partial pressure, the components The theoretical equilibrium adsorption capacity, in mol / kg. Components The actual average adsorption capacity is expressed in mol / kg. It can be clearly seen from the above modified formula that the pulse amplitude and frequency The introduction of [a specific ingredient] resulted in a multiple increase in the desorption rate, shortening the regeneration time and improving the regeneration efficiency.

[0078] Second, the destructive effect of transient shear force on the stagnant boundary layer. In traditional steady-state gas flow washing regeneration, a stagnant gas boundary layer forms on the surface of the adsorbent particles. Desorbed impurity molecules must pass through this boundary layer via extremely slow molecular diffusion to be carried away by the gas flow, which constitutes the main mass transfer resistance during regeneration. However, under pulsed gas flow, the drastic periodic fluctuations in flow velocity generate enormous transient shear force on the surface of the adsorbent particles. The mathematical expression for transient wall shear force is: ; in, Over time The changing transient wall shear force, measured in Pascals (Pa). : Steady-state shear force corresponding to average flow velocity, in Pascals (Pa). : Shear force amplitude caused by the pulse, in Pascals (Pa); Pulse frequency, measured in Hertz (Hz); : Time variable, in seconds (s); Phase angle, dimensionless, reflects the phase difference between velocity fluctuations and shear force fluctuations; This high-frequency alternating transient shear force It can effectively tear and peel away the stagnant boundary layer on the surface of the adsorbent, generating strong micro-eddies that rapidly entrain desorbed impurity molecules into the bulk gas phase and carry them out of the bed. Especially for hydrogen sulfide and heavy hydrocarbon molecules with extremely strong adsorption capacity, the mechanical peeling effect of pulse shear force can achieve deep regeneration, fully restore the initial activity of the adsorbent, and prevent the long-term accumulation of impurities.

[0079] Module 5: Tail gas recovery and energy allocation module, connected to the pressure swing adsorption primary purification module, includes a turbine expander and a catalytic combustion reactor, used to receive the desorbed tail gas, recover pressure energy through the turbine expander and output low-temperature tail gas to cool the adsorption tower, and convert the tail gas into heat energy through the catalytic combustion reactor to heat the membrane separation deep purification module and the feed gas pretreatment module. During the reverse depressurization step of the pressure swing adsorption (PSA) primary purification module and the flushing step of the retentate gas pulse regeneration control module, a large amount of low-pressure tail gas (desorption gas) is generated. This tail gas contains a large amount of impurities desorbed from the adsorbent (such as carbon monoxide, carbon dioxide, methane, hydrogen sulfide, etc.) and a small amount of unrecovered hydrogen. At the same time, although the pressure of this tail gas has been significantly reduced, it still has a certain residual pressure (approximately 0.15 to 0.3 MPa) and considerable chemical energy (lower heating value).

[0080] Traditional processes often treat this exhaust gas as waste, directly discharging it or simply burning it, resulting in significant energy waste and environmental thermal pollution. Module 5 is designed to break away from this extensive treatment method, transforming these waste material streams into a deeply usable energy stream within the system, achieving energy self-sufficiency and global optimized configuration throughout the process, thereby reducing the production cost of ultra-high purity hydrogen. This module mainly comprises three highly integrated sub-units: an exhaust gas buffer and pressure stabilization unit, a turbine expansion pressure energy recovery unit, and a catalytic combustion and thermal energy cascade utilization unit.

[0081] Because pressure swing adsorption (PSA) is a periodic dynamic process involving multiple alternating towers, the exhaust gas flow rate and pressure exhibit extremely drastic fluctuations over time. Directly introducing this pulsating gas flow into downstream rotating machinery (such as turbine expanders) and combustion equipment would lead to highly unstable equipment operation, and could even cause severe mechanical vibrations and combustion failure. Therefore, it is essential to first perform large-capacity buffering and pressure stabilization of the exhaust gas.

[0082] This unit employs a rigid, large-capacity buffer tank with a precision back pressure regulating valve. The tank's interior is lined with a corrosion-resistant epoxy resin to protect against the weakly acidic corrosion caused by the combination of hydrogen sulfide and moisture in the exhaust gas. When pulsating exhaust gas enters the rigid buffer tank, the dynamic pressure change within the tank follows the law of conservation of mass and the differential form of the ideal gas law: ; in, : The rate of change of pressure inside the buffer tank over time, expressed in Pascals per second (Pa / s).

[0083] : The time variable of the buffer voltage regulation process, in seconds (s); : A specific gas constant for the mixed exhaust gas, expressed in joules per kilogram Kelvin (J / (kg·K)), which is dynamically updated as the exhaust gas composition changes in real time; : Absolute temperature of the gas inside the buffer tank, in Kelvin (K). The fixed physical volume of the buffer tank, in cubic meters; The sum of instantaneous tail gas inflow mass flow rates from each adsorption tower in the depressurization and flushing state, expressed in kilograms per second (kg / s). This value is an input variable that fluctuates wildly. : Mass flow rate of the buffer tank into the downstream energy recovery unit, expressed in kilograms per second (kg / s).

[0084] The system monitors in real time using a feedforward-feedback composite control algorithm. The fluctuation trend was monitored, and the opening of the precision pneumatic regulating valve at the outlet of the buffer tank was adjusted in advance to ensure... It remains constant throughout. Through this dynamic volume compensation mechanism, the drastically fluctuating intermittent airflow is successfully transformed into a stable, continuous airflow, providing an extremely stable operating condition benchmark for subsequent energy recovery.

[0085] The stabilized exhaust gas enters the centripetal turboexpander. The turboexpander is a precision, high-speed rotating fluid machine. The exhaust gas is accelerated in the expander's guide vane and then enters the high-speed rotating impeller for adiabatic expansion. During expansion, the thermodynamic enthalpy of the gas molecules decreases, driving the impeller to rotate at high speed, thus converting the gas's pressure energy into mechanical shaft work. This mechanical energy is converted into electrical energy by a coaxially connected high-efficiency permanent magnet synchronous generator. After frequency conversion and rectification, it is directly integrated into the system's internal power supply network to drive various pumps and control valves in the feed gas pretreatment module, achieving partial self-sufficiency in electrical energy.

[0086] The actual shaft power output of a turboexpander is calculated using the following thermodynamic formula: ; in, : The actual output shaft power of the turbine expander, in watts (W). Mass flow rate of exhaust gas entering the expander, in kilograms per second (kg / s). : The specific heat capacity at constant pressure of the mixed exhaust gas, expressed in joules per kilogram Kelvin (J / (kg·K)). : Absolute temperature of exhaust gas when it enters the expander, in Kelvin (K). The isentropic efficiency of an expander is a dimensionless parameter, typically between 0.75 and 0.85, reflecting the degree to which the actual expansion process deviates from the ideal isentropic process (mainly caused by internal fluid friction and eddy current losses). The absolute pressure at the inlet of the expander, measured in Pascals (Pa). The absolute pressure at the outlet of the expander (usually slightly higher than the local atmospheric pressure to overcome the resistance of the subsequent pipeline), measured in Pascals (Pa). : The adiabatic index (specific heat ratio, i.e., the ratio of specific heat capacity at constant pressure to specific heat capacity at constant volume) of the mixed exhaust gas, dimensionless; In addition to recovering electrical energy, the turbine expansion process is accompanied by a significant throttling and cooling effect (an extension of the Joule-Thomson effect). After the exhaust gas expands and performs work, its temperature drops sharply (typically to between -20°C and 0°C). This portion of the low-temperature exhaust gas, containing valuable cooling capacity, is not directly emitted but is cleverly introduced into the external cooling jacket of the pressure swing adsorption (PSA) primary purification module. Since the adsorption process is a strongly exothermic reaction, an increase in bed temperature leads to a decrease in adsorbent capacity. Introducing this portion of low-temperature exhaust gas as a cooling medium can effectively absorb the heat of adsorption, suppress the bed temperature rise, and thus further improve the impurity adsorption capacity of the adsorbent, achieving a match between the thermodynamic heat source and cold source within the system.

[0087] After expansion, cooling, and absorption of adsorption heat, the exhaust gas, although its pressure has dropped to atmospheric pressure, still contains methane, carbon monoxide, and trace amounts of unrecovered hydrogen, and has a considerable low heating value. This portion of the gas finally enters the catalytic combustion reactor.

[0088] Traditional open-flame combustion suffers from incomplete combustion, secondary pollution from nitrogen oxides (NOx), and uneven heat distribution. This unit employs advanced flameless catalytic combustion technology. The reactor is filled with a honeycomb cordierite ceramic catalyst supported on precious metal nanoparticles such as platinum (Pt) or palladium (Pd). Due to the reduced activation energy of the precious metal catalyst, the combustible components in the exhaust gas undergo a deep flameless oxidation reaction with the introduced combustion air at extremely low temperatures (300℃ to 450℃), releasing a large amount of heat energy and completely avoiding the formation of high-temperature thermal NOx.

[0089] Taking the catalytic combustion of methane, carbon monoxide, and hydrogen as an example, the exothermic rate model is as follows: ; in, : Total heat release rate of the catalytic combustion reactor, in watts (W); : These are the molar flow rates of methane, carbon monoxide, and hydrogen in the exhaust gas, respectively, in moles per second (mol / s). : Standard molar enthalpy of combustion (positive values) for methane, carbon monoxide, and hydrogen, respectively, in joules per mole (J / mol); : These represent the conversion rates of each combustible component in the catalyst bed, dimensionless. Due to the high efficiency of the catalyst, this value can typically reach above 0.98. The high-temperature clean flue gas (approximately 500°C to 600°C) generated by catalytic combustion is introduced into a carefully designed thermal energy cascade utilization network to achieve "dry-out" utilization of energy. First stage (high temperature section utilization): The highest temperature flue gas first enters the heating jacket of the membrane separation deep purification module, providing a large amount of heat required to maintain the optimal operating temperature of 350℃ to 400℃ for the palladium-silver alloy membrane, completely replacing the high energy consumption electric heating method in the traditional process.

[0090] The second stage (medium temperature section utilization): The flue gas cooled by the first stage (temperature of about 200℃ to 250℃) enters the constant temperature heating and regulation unit of the feed gas pretreatment module to heat the raw gas and make its temperature higher than the dew point to prevent capillary condensation.

[0091] The third stage (low-temperature utilization): The remaining low-grade heat energy (temperature approximately 100℃ to 150℃) enters the air preheater to preheat the cold combustion air entering the catalytic combustion reactor, thereby improving combustion efficiency. After three stages of utilization, the flue gas temperature drops to a safe range, ultimately meeting emission standards.

[0092] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

[0093] It should be noted that, in this document, the use of relational terms such as "first" and "second" is merely for distinguishing one entity or operation from another, and does not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0094] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0095] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0096] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hydrogen purification system based on the synergistic effect of adsorption and membrane separation, characterized in that, include: The feed gas pretreatment module is used to receive the raw gas, and then pass it through a cyclone gas-liquid separation unit, a wire mesh defoaming filter unit, and a constant temperature heating and regulating unit to remove droplets and dust, and regulate the gas temperature. The pressure swing adsorption primary purification module is used to receive the pretreated gas, remove impurities, and output primary pure hydrogen. The membrane separation deep purification module is used to receive primary pure hydrogen, output ultra-high purity hydrogen product in the tube side, and output high-pressure intercept gas in the shell side. The intercepted gas pulse regeneration control module is used to convert high-pressure intercepted gas into high-frequency pulsed gas flow and inject it in reverse into the radial flow adsorption tower in the regeneration state to remove impurities. The exhaust gas recovery and energy distribution module is used to receive the desorption exhaust gas, recover pressure energy through a turbine expander and output low-temperature exhaust gas to cool the adsorption tower, and convert the exhaust gas into heat energy through a catalytic combustion reactor to heat the membrane separation deep purification module and the feed gas pretreatment module.

2. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 1, characterized in that, The cyclone gas-liquid separation unit includes a cylindrical shell and a liquid collecting cone. The raw material gas enters the cylindrical shell through a tangential inlet pipe to form an outer vortex. Determination of the critical separation particle size of the cyclone gas-liquid separation unit: ; in, The dynamic viscosity of the raw gas; The width of the rectangular inlet of the cyclone gas-liquid separation unit; The effective number of rotations of the airflow within the cyclone gas-liquid separation unit; The linear velocity of the raw gas at the inlet; The density of the droplet or solid particle; This represents the density of the raw gas.

3. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 2, characterized in that, The wire mesh defogging filter unit consists of multiple layers of interwoven micro-wire mesh pads with a hydrophobic and oleophobic coating on the surface. The constant temperature heat tracing and regulating unit adopts a shell-and-tube heat exchange structure, with the raw material gas introduced into the tube side and the heating medium introduced into the shell side; The heat transfer rate of the constant temperature heat tracing unit is through Sure; in, The overall heat transfer coefficient; This refers to the effective heat transfer area of ​​the heat exchanger tube; The temperature difference is the logarithmic mean.

4. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 1, characterized in that, The pressure swing adsorption primary purification module contains multiple radial flow adsorption towers connected in parallel, and each radial flow adsorption tower has a built-in gradient composite adsorbent bed. The radial flow adsorption tower includes an outer shell, an outer gas distribution cylinder, and an inner gas collection cylinder, with a gradient composite adsorbent bed filling the space between the outer gas distribution cylinder and the inner gas collection cylinder. The gradient composite adsorbent bed is divided into three gradient layers from the outside to the inside along the radial flow direction of the airflow: the outermost layer filled with activated alumina particles, the middle layer filled with modified coal-based activated carbon, and the innermost layer filled with low silica-alumina ratio zeolite molecular sieves.

5. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 4, characterized in that, Basis for determining the equilibrium adsorption capacity of multi-component competitive adsorption in a gradient composite adsorbent bed: ; in, Components The amount of saturated monolayer adsorption; Components The adsorption affinity constant; Components Partial pressure in the gas phase; Components The adsorption heterogeneity index; This represents the total number of adsorbable components in the gas mixture. For summation index, it represents each component in the gas mixture.

6. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 1, characterized in that, The membrane separation deep purification module is equipped with a composite palladium-silver alloy membrane tube: The composite palladium-silver alloy membrane tube adopts an asymmetric composite structure, including a porous alumina ceramic tube support layer, a mesoporous transition layer, and a dense palladium-silver alloy thin film separation layer. The shell side of the membrane separation deep purification module is equipped with multi-stage spiral baffles, which force the airflow to laterally sweep the surface of the composite palladium-silver alloy membrane tube in a spiral shape to suppress concentration polarization.

7. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 6, characterized in that, The hydrogen permeation flux of the composite palladium-silver alloy membrane tube is: ; in, The pre-exponential factor for membrane materials; The apparent activation energy is the diffusion energy of hydrogen atoms in the palladium-silver alloy lattice. It is the ideal gas constant; This refers to the absolute operating temperature of the membrane module. The thickness of the dense palladium-silver alloy thin film separation layer; This represents the partial pressure of hydrogen in the shell side; This represents the partial pressure of hydrogen gas in the tube side; This is a stress index.

8. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 1, characterized in that, The intercepted gas pulse regeneration control module is equipped with a fluid jet oscillator: The fluid jet oscillator internally includes a converging nozzle, a wedge-shaped flow divider, a feedback channel, and an attached sidewall; The oscillation frequency of the high-frequency pulsed airflow is constant: ;in, These are Strauhal numbers; To trap the jet velocity of the gas at the constricting nozzle; This is the equivalent diameter of the shrink nozzle.

9. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 8, characterized in that, When a high-frequency pulsed gas flow is injected in reverse into a radial flow adsorption tower in the regeneration state, an alternating local pressure gradient and transient shear force are generated outside the micropores of the adsorbent. The desorption rate of impurities is: ; in, The time variable is the desorption and regeneration process; The total mass transfer coefficient under steady-state conditions; The impulse enhancement response coefficient; The pressure amplitude of the pulsed airflow; The frequency of the pulsed airflow; For the components under the current transient gas phase partial pressure Theoretical equilibrium adsorption amount; Components The actual average adsorption amount.

10. The hydrogen purification system based on the synergistic effect of adsorption and membrane separation according to claim 1, characterized in that, The exhaust gas recovery and energy distribution module also includes a rigid buffer tank with a back pressure regulating valve. The desorbed exhaust gas first enters the rigid buffer tank for pressure stabilization before entering the turbine expander. The catalytic combustion reactor is filled with a honeycomb ceramic catalyst loaded with precious metals. The high-temperature flue gas generated by the catalytic combustion reactor enters the heating jacket of the membrane separation deep purification module, the shell side of the constant temperature heat tracing and regulating unit, and the air preheater in sequence to realize the cascade utilization of thermal energy. The actual shaft power output of the turbine expander is: ;in, The exhaust gas mass flow rate entering the turbine expander; The specific heat capacity at constant pressure of the mixed exhaust gas; The absolute temperature of the exhaust gas when it enters the turbine expander; The isentropic efficiency of the turbine expander; This refers to the absolute pressure at the inlet of the turbine expander. This refers to the absolute pressure at the outlet of the turbine expander. It represents the adiabatic index of the mixed exhaust gas.

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