Purification device for yellow phosphorus tail gas

Abstract

The present application relates to yellow phosphorus tail gas treatment technical field, specifically disclose a kind of yellow phosphorus tail gas purification device, including magnetization pretreatment unit and depth catalytic oxidation unit sequentially arranged and communicated along tail gas flow direction;The depth catalytic oxidation unit includes electric heating catalytic reactor, and multiple layers of electric heating catalytic net are arranged in its inside with interval, the electric heating catalytic net is perpendicular to tail gas flow direction, and each layer electric heating catalytic net is electrically connected by conductive structure.The yellow phosphorus tail gas treatment device is improved by optimization, can effectively avoid the absolute dependence of traditional spray washing on droplet atomization quality, avoid the problem of nozzle blockage and flow field uneven, thereby realizing the deep removal of PH3 and other difficult-to-treat components.

Description

Technical Field

[0001] This invention relates to the field of yellow phosphorus tail gas treatment technology, and specifically to a yellow phosphorus tail gas purification device. Background Technology

[0002] The exhaust gas emitted from electric furnaces used in the production of yellow phosphorus is complex and highly hazardous, primarily containing high concentrations of carbon monoxide (CO), as well as phosphine (PH3), hydrogen sulfide (H2S), hydrogen fluoride (HF), dust, hydrogen cyanide, and other toxic and harmful impurities. Without thorough purification, this exhaust gas cannot be utilized as a chemical raw material or fuel; direct emission poses a serious threat to the environment and human health. Therefore, efficient scrubbing and deep purification of yellow phosphorus exhaust gas is essential for the sustainable development of the industry.

[0003] Currently, spray scrubbing tower technology is widely used in the pretreatment stage of exhaust gas in the industry. Its core is to atomize the scrubbing liquid (usually water or alkaline solution) through nozzles, and then transfer mass with the exhaust gas in countercurrent or cocurrent flow to absorb and remove acidic gases and dust. However, the existing spray scrubbing technology based on ordinary nozzles has revealed several inherent defects in actual industrial operation, which seriously restricts the purification efficiency, operational stability and economy.

[0004] Conventional pressure or spiral nozzles produce droplets with a large average size (typically greater than 500 micrometers) and a wide droplet size distribution, resulting in a limited effective contact surface area between the gas and liquid phases. Larger droplets also exhibit high internal mass transfer resistance and fall at high speeds, leading to short contact times with the exhaust gas. These factors collectively result in low gas-liquid mass transfer efficiency, particularly for components requiring rapid chemical absorption, such as phosphine, making it difficult to achieve the purification effect required for deep resource utilization.

[0005] Yellow phosphorus exhaust gas contains a large amount of phosphorus dust and reaction intermediates, which easily generate slightly soluble or viscous substances such as phosphates during the washing process. These substances readily deposit and scale in the internal channels and outlets of the nozzles, leading to reduced nozzle flow, altered atomization angle, and even complete blockage. Frequent blockages force the system to be shut down for manual cleaning or nozzle replacement, disrupting production continuity and significantly increasing manual maintenance costs and spare parts consumption.

[0006] Fixed-installation nozzles have relatively fixed spray angles and ranges, making it difficult to dynamically adapt to the actual airflow distribution within the tower. Under complex flow fields, localized areas may experience excessively low spray density, creating spray blind zones. Simultaneously, the accumulation and downward flow of the scrubbing liquid on the tower wall can form wall flow, causing some exhaust gas to short-circuit through the scrubbing zone without sufficient contact with the scrubbing liquid. These phenomena all result in incomplete purification of some exhaust gases, affecting the overall purification effect and stability.

[0007] To overcome these shortcomings, the industry has attempted methods such as improving nozzle materials, adding pre-washing sections, or multi-stage series towers. However, these often only address the symptoms, not the root cause, or introduce new problems such as increased energy consumption and system complexity while solving one issue. Therefore, further optimization and improvement of the yellow phosphorus tail gas treatment device are needed to effectively avoid the absolute dependence of traditional spray washing on droplet atomization quality, avoid the problems of nozzle clogging and uneven flow field, and thus achieve deep removal of difficult-to-treat components such as PH3. Summary of the Invention

[0008] The purpose of this invention is to provide a yellow phosphorus tail gas purification device that effectively avoids the absolute dependence on droplet atomization quality of traditional spray washing, avoids the problems of nozzle clogging and uneven flow field, and thus achieves deep removal of difficult-to-treat components such as PH3.

[0009] This invention is achieved through the following technical solution:

[0010] A yellow phosphorus tail gas purification device includes a magnetization pretreatment unit and a deep catalytic oxidation unit arranged sequentially and connected along the tail gas flow direction.

[0011] The deep catalytic oxidation unit includes an electrothermal catalytic reactor, which has multiple layers of spaced electrothermal catalytic mesh inside. The electrothermal catalytic mesh is perpendicular to the exhaust gas flow direction, and the layers of electrothermal catalytic mesh are electrically connected through a conductive structure.

[0012] In one possible design, the electrothermal catalytic network includes a conductive substrate and a layer of catalytically active material supported on its surface. The catalytically active material layer is a gradient loading structure along the airflow direction, wherein the loading of active components gradually increases or the types of active components vary according to their oxidation capacity.

[0013] In one possible design, the conductive substrate is a metal honeycomb or metal fiber felt; the active component of the catalytic active material layer is a transition metal oxide, and the support is an active alumina coating.

[0014] In one possible design, the pore density of the metal honeycomb is 100-400 mesh, and the porosity of the metal fiber felt is greater than 85% and the fiber diameter is 10-50 micrometers.

[0015] In one possible design, the magnetization pretreatment unit includes at least one tubular magnetizer, in which a non-uniform strong magnetic field is formed, the direction of which is perpendicular to the exhaust gas direction or at an angle of 45°-90°.

[0016] In one possible design, the magnetization pretreatment unit includes two magnetizers connected in series, with the magnetic field directions within adjacent magnetizers perpendicular to each other.

[0017] In one possible design, the magnetic field is generated by electromagnetic coils wound in segments along the axis of the tubular magnetizer, each segment of which can be independently controlled to create a magnetic field intensity gradient or pulsed magnetic field in the direction of airflow.

[0018] In one possible design, the yellow phosphorus tail gas purification device further includes an aerosol condensation separator located downstream of the deep catalytic oxidation unit; the aerosol condensation separator contains multiple condensation plates arranged in a herringbone or wave-shaped array, the surface of the condensation plates is provided with a hydrophobic and oleophobic coating and / or raised texture, and the surface of the condensation plates forms an acute angle with the horizontal air intake direction.

[0019] In one possible design, the magnetization pretreatment unit is integrated with the deep catalytic oxidation unit within the same housing, with the magnetizer located at the inlet end of the electrothermal catalytic reactor.

[0020] In one possible design, the yellow phosphorus tail gas purification device further includes a controller and a concentration detector. The concentration detector is used to detect pollutant concentration information at the air inlet of the deep catalytic oxidation unit. The controller is communicatively connected to the power supply of the concentration detector and the electrothermal catalytic grid, and is used to dynamically adjust the input power of the electrothermal catalytic grid according to the pollutant concentration information.

[0021] In one possible design, the concentration detector is a phosphine concentration sensor and / or a particulate matter concentration sensor.

[0022] The advantages of this invention over the prior art are as follows:

[0023] Yellow phosphorus tail gas containing complex and harmful components enters the magnetization pretreatment unit. In this unit, the tail gas is exposed to a non-uniform strong magnetic field in a specific direction (at a large angle with the airflow direction). Under the magnetic effects of Lorentz force, magnetic moment orientation force, and other magnetic forces, the trajectory of certain paramagnetic or polar molecules, fine particulate matter, and aerosol precursors carried in the tail gas is deflected, and the probability of them colliding with each other increases. This promotes physical magnetoagglomeration or conformational changes, thereby initially agglomerating some submicron-sized fine pollutants into larger particles that are easier to capture or treat by subsequent processes. At the same time, it may weaken some molecular bond energies, creating favorable conditions for deep oxidation.

[0024] Subsequently, the pre-treated exhaust gas with magnetization enters the deep catalytic oxidation unit. The catalytic mesh, acting as a resistive heating element, rapidly heats to the temperature required for the catalytic reaction upon energization. Simultaneously, the catalytically active material loaded on its surface provides active sites for the deep oxidation of pollutant molecules. As the exhaust gas flows through these catalytic mesh layers arranged perpendicular to the gas flow direction and spaced apart, a tortuous and elongated flow path is formed. Pollutant molecules come into full contact with the high-temperature catalytic surface and react with oxygen under catalytic action, being completely oxidized into stable oxides such as phosphoric anhydride, sulfur dioxide, and hydrogen fluoride, which are easily processed later, or further converted into corresponding acid mists.

[0025] Driven by an induced draft fan, the yellow phosphorus exhaust gas first flows through a magnetization pretreatment unit. While flowing through this unit, the pollutants in the exhaust gas undergo preliminary physicochemical adjustments under the influence of the magnetic field. Subsequently, the gas enters the electrothermal catalytic reactor of the deep catalytic oxidation unit. Upon reactor startup, power is supplied to a multi-layered electrothermal catalytic mesh via an external power source. Each layer of the mesh forms an electrical circuit through a conductive structure and rapidly heats up. After entering the reactor inlet, the exhaust gas sequentially passes through each layer of incandescent catalytic mesh, which is maintained at a certain spacing. At each mesh, the gas undergoes intense heat and mass transfer with the catalytic surface, and the harmful components are catalytically oxidized. The purified high-temperature gas is finally discharged from the reactor outlet and enters the subsequent cooling or absorption section. The entire process is continuous, and the power of the electrothermal catalytic mesh can be adjusted as needed to maintain the optimal reaction temperature.

[0026] In this way, the magnetization pretreatment unit pre-conditions the exhaust gas through the action of a physical field. This not only captures some particulate matter, but also reduces the load and difficulty of the subsequent catalytic oxidation process by promoting agglomeration and changing the molecular state. This makes it easier to treat components that are difficult to oxidize directly. The two are connected in series to form a coordinated structure of physical pretreatment, heating, and chemical destruction, which is conducive to improving the overall purification efficiency.

[0027] The electrothermal catalytic mesh structure, arranged in multiple layers perpendicular to the airflow, breaks away from the traditional tightly packed catalyst bed pattern. The interleaved arrangement creates open airflow channels, reducing system airflow resistance (pressure drop) and minimizing fan energy consumption. Simultaneously, this structure forces moderate turbulence between the mesh layers, enhancing mass transfer between the gas and catalyst surface, ensuring sufficient contact between the exhaust gas and the catalytically active surface.

[0028] The electrothermal catalytic mesh integrates catalysis and electroheating functions, generating heat directly near the catalytic active sites. This results in a very short heat transfer path, minimal heat loss, and high energy utilization efficiency. Its multi-layered design increases the catalytic surface area, ensuring uniform heating of each layer and maintaining an active catalytic environment across the entire reaction cross-section. This promotes the complete oxidation of pollutants, thereby achieving highly efficient purification of yellow phosphorus tail gas. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of the yellow phosphorus tail gas purification device provided by the present invention in one embodiment;

[0031] Figure 2 This is a schematic diagram of the electrothermal catalytic mesh in one embodiment of the yellow phosphorus tail gas purification device provided by the present invention;

[0032] Figure 3 This is a cross-sectional view of the electrothermal catalytic mesh in one embodiment of the yellow phosphorus tail gas purification device provided by the present invention;

[0033] Figure 4 This is a schematic diagram of the aerosol condensation separator in the yellow phosphorus tail gas purification device provided by the present invention.

[0034] The markings and corresponding component names in the attached diagram are as follows: 1-Magnetizer, 2-Electrothermal catalytic mesh, 21-Conductive substrate, 22-Catalytic active material layer, 3-Aerosol condensation separator, 31-Condensation plate, 32-Raised texture, 4-Shell. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that while the description of these embodiments is intended to aid in understanding the invention, it does not constitute a limitation thereof. The specific structural and functional details disclosed herein are only for describing exemplary embodiments of the invention. However, the invention can be embodied in many alternative forms and should not be construed as being limited to the embodiments described herein.

[0036] According to a first aspect of this disclosure, a yellow phosphorus tail gas purification device is provided. Wherein, Figures 1 to 4 Specific embodiments thereof are shown.

[0037] See Figures 1 to 4 As shown, the yellow phosphorus tail gas purification device includes a magnetization pretreatment unit and a deep catalytic oxidation unit arranged sequentially and connected along the tail gas flow direction; the deep catalytic oxidation unit includes an electrothermal catalytic reactor, which has multiple layers of spaced electrothermal catalytic mesh 2 inside. The electrothermal catalytic mesh 2 is perpendicular to the tail gas flow direction, and each layer of electrothermal catalytic mesh 2 is electrically connected through a conductive structure.

[0038] Yellow phosphorus tail gas containing complex and harmful components enters the magnetization pretreatment unit. In this unit, the tail gas is exposed to a non-uniform strong magnetic field in a specific direction (at a large angle with the airflow direction). Under the magnetic effects of Lorentz force, magnetic moment orientation force, and other magnetic forces, the trajectory of certain paramagnetic or polar molecules, fine particulate matter, and aerosol precursors carried in the tail gas is deflected, and the probability of them colliding with each other increases. This promotes physical magnetoagglomeration or conformational changes, thereby initially agglomerating some submicron-sized fine pollutants into larger particles that are easier to capture or treat by subsequent processes. At the same time, it may weaken some molecular bond energies, creating favorable conditions for deep oxidation.

[0039] Subsequently, the pre-treated exhaust gas with magnetization enters the deep catalytic oxidation unit. The catalytic mesh, acting as a resistive heating element, rapidly heats to the temperature required for the catalytic reaction upon energization. Simultaneously, the catalytically active material loaded on its surface provides active sites for the deep oxidation of pollutant molecules. As the exhaust gas flows through these catalytic mesh layers arranged perpendicular to the gas flow direction and spaced apart, a tortuous and elongated flow path is formed. Pollutant molecules come into full contact with the high-temperature catalytic surface and react with oxygen under catalytic action, being completely oxidized into stable oxides such as phosphoric anhydride, sulfur dioxide, and hydrogen fluoride, which are easily processed later, or further converted into corresponding acid mists.

[0040] Driven by an induced draft fan, the yellow phosphorus exhaust gas first flows through a magnetization pretreatment unit. While flowing through this unit, the pollutants in the exhaust gas undergo preliminary physicochemical adjustments under the influence of the magnetic field. Subsequently, the gas enters the electrothermal catalytic reactor of the deep catalytic oxidation unit. Upon reactor startup, power is supplied to the multi-layer electrothermal catalytic mesh 2 via an external power source. Each layer of the mesh forms an electrical circuit through a conductive structure and rapidly heats up. After entering the reactor inlet, the exhaust gas sequentially passes through each layer of incandescent catalytic mesh, which is maintained at a certain spacing. On each mesh, the gas undergoes intense heat and mass transfer with the catalytic surface, and the harmful components are catalytically oxidized. The purified high-temperature gas is finally discharged from the reactor outlet and enters the subsequent cooling or absorption section. The entire process is continuous, and the power of the electrothermal catalytic mesh 2 can be adjusted as needed to maintain the optimal reaction temperature.

[0041] In this way, the magnetization pretreatment unit pre-conditions the exhaust gas through the action of a physical field. This not only captures some particulate matter, but also reduces the load and difficulty of the subsequent catalytic oxidation process by promoting agglomeration and changing the molecular state. This makes it easier to treat components that are difficult to oxidize directly. The two are connected in series to form a coordinated structure of physical pretreatment, heating, and chemical destruction, which is conducive to improving the overall purification efficiency.

[0042] The electrothermal catalytic mesh 2 structure, with its multi-layered, spaced arrangement perpendicular to the airflow, breaks away from the traditional tightly packed catalyst bed model. The spaced arrangement creates open airflow channels, reducing system airflow resistance (pressure drop) and minimizing fan energy consumption. Simultaneously, this structure forces moderate turbulence between the mesh layers, enhancing mass transfer between the gas and catalyst surface, ensuring sufficient contact between the exhaust gas and the catalytically active surface.

[0043] The electrothermal catalytic mesh 2 integrates catalysis and electroheating functions, generating heat directly near the catalytic active sites. This results in a very short heat transfer path, minimal heat loss, and high energy utilization efficiency. Its multi-layer design increases the catalytic surface area, ensuring uniform heating of each mesh layer and maintaining an active catalytic environment across the entire reaction cross-section. This promotes the complete oxidation of pollutants, thereby achieving highly efficient purification of yellow phosphorus tail gas.

[0044] It should be noted that directional terms such as "inner" and "outer" refer to "inner" and "outer" relative to the contour of the component; "inner" refers to the direction towards the component, and "outer" refers to the direction away from it. Furthermore, it should be noted that terms such as "first" and "second" are used to distinguish one element from another and do not indicate sequence or importance. Moreover, in the accompanying drawings, the same reference numerals in different drawings represent the same element. It should be noted that "and / or" in the text refers to A and / or B, indicating that there are three possible scenarios: only A, only B, and both A and B. Conversely, "and" in the text refers to A and B, indicating that there are two possible scenarios: only A and both A and B.

[0045] In one embodiment provided in this disclosure, the electrothermal catalytic mesh 2 includes a conductive substrate 21 and a catalytically active material layer 22 loaded on its surface. The catalytically active material layer 22 is a gradient loading structure along the airflow direction, wherein the loading amount of the active component gradually increases or the types of active components change according to the gradient of oxidation capacity.

[0046] Yellow phosphorus tail gas typically contains various reducing pollutants (such as PH3, H2S, COS, and organophosphorus compounds), with varying chemical stability and reactivity. By creating a gradient change in the catalytic active material layer 22 along the gas flow direction, a gradient reaction field matching the reaction difficulty and catalytic intensity can be formed. The front-end catalytic loading is low or the oxidation capacity is mild, mainly targeting easily oxidized components for preliminary conversion, avoiding sintering or wasted energy consumption that may be caused by over-reaction; the back-end catalytic loading is higher or uses more oxidizing active components, specifically designed to overcome the more stubborn pollutants remaining in the front-end, providing sufficient catalytic aggression to ensure complete oxidation.

[0047] When the pretreated exhaust gas passes through the multi-layer electrothermal catalytic mesh 2, the purification process does not occur uniformly across all mesh layers. Instead, it follows a graded, progressive reaction path guided by the gradient loading structure. The gas first contacts the front-end catalytic mesh, where the active components with lower loading or relatively mild oxidizing power preferentially capture and rapidly convert the most easily oxidized pollutants in the exhaust gas (such as some PH3) into intermediate products or primary oxides. Subsequently, the gas flow carries the remaining pollutants and intermediate products into subsequent mesh layers. As the loading of active components gradually increases or their oxidizing power successively strengthens, the driving force of the reaction increases synchronously. Pollutants with lower reactivity that were not completely oxidized in the front stage (such as some organophosphorus impurities) and potential intermediate products (such as partially oxidized phosphorus oxides) are further deeply oxidized at more concentrated or stronger catalytically active sites, ultimately transforming into the target end products (such as P2O5, SO2, etc.). The entire process achieves selective and sequential transformation of pollutants.

[0048] Therefore, by matching catalytic intensity with reaction difficulty, all pollutants, from easy to difficult, can be efficiently and thoroughly oxidized at appropriate reaction stages, improving overall purification efficiency and the purification depth of the outlet gas. At the same time, it avoids the risk of localized rapid deactivation or sintering caused by concentrating all highly active, high-load catalysts at the front end to react rapidly with easily oxidized components. This allows for more balanced and economical consumption of catalytic activity in each stage, slowing down the overall catalyst deactivation rate, improving the utilization efficiency of precious metals or active components, reducing operating costs, and extending the overall service life of the catalytic network.

[0049] Furthermore, the conductive substrate 21 is a metal honeycomb or metal fiber felt; the active component of the catalytic active material layer 22 is a transition metal oxide, and the support is an active alumina coating.

[0050] The metal honeycomb or metal fiber felt is composed of metals (such as iron-chromium-aluminum, nickel-based alloys, etc.), giving the conductive substrate 21 excellent electrical conductivity. This enables efficient conversion of electrical energy into heat energy, achieving rapid and uniform resistance heating to meet the precise temperature requirements of the catalytic reaction. Simultaneously, the high thermal conductivity of the metal material ensures rapid heat diffusion within and on the surface of the substrate, preventing localized overheating or cold spots, maintaining the temperature uniformity of the catalytic active layer, and thus ensuring stable catalytic reaction efficiency.

[0051] Metal honeycomb structures, with their regular pore structure and high geometrical surface area, provide a broad loading platform for the catalytic active layer while ensuring low airflow resistance, thus increasing the gas-solid reaction interface. Metal fiber felts, with their three-dimensional network structure and high porosity, effectively turbulent the flow and enhance gas-solid mass transfer. Their flexible fiber structure also endows the substrate with excellent thermal shock resistance and mechanical adaptability. Both materials possess sufficient structural strength and thermal stability to withstand thermal stress and airflow impacts from device start-up and shutdown, and fluctuations in operating conditions, ensuring reliable long-term operation in high-temperature reaction environments.

[0052] Transition metal oxides (such as MnO) X Using Co3O4, CuO, or composite oxides as active components, based on their rich valence states, high redox activity, and certain affinity for elements such as phosphorus and sulfur, they can activate oxygen molecules at relatively mild temperatures, attack the molecular bonds of pollutants, and promote their deep oxidation. They have good catalytic activity and target product selectivity, and are particularly suitable for catalytic oxidation of characteristic pollutants in yellow phosphorus tail gas such as PH3 and H2S.

[0053] Activated alumina coatings, acting as a carrier, can increase the dispersion of active components, expose more active sites, and improve catalytic efficiency. Secondly, alumina possesses excellent thermal stability and chemical inertness, maintaining structural stability in high-temperature reaction environments, protecting the metal substrate from corrosion, and preventing adverse interactions between the active components and the substrate.

[0054] By combining a metal substrate, an alumina support, and a transition metal oxide active component, the metal substrate is responsible for efficient heat generation and transfer, the alumina support is responsible for stable loading and dispersion, and the transition metal oxide provides catalytic active centers. Based on this integrated conductive-support-catalytic structure, efficient synergy of heat transfer, reactant mass transfer, and surface catalytic reactions can be achieved, reducing intermediate steps in energy and mass transfer and improving the overall efficiency of the electrothermal catalytic process.

[0055] Specifically, the pore density of the metal honeycomb is 100-400 mesh, and the porosity of the metal fiber felt is greater than 85% with a fiber diameter of 10-50 micrometers.

[0056] Based on the pore density setting of the metal honeycomb structure, it possesses dense and regular microchannels. The honeycomb structure has an extremely high geometrical specific surface area, which is beneficial for providing ample loading space for catalytically active materials, thereby enabling it to accommodate a large number of active sites. At the same time, the channel size within this mesh range is optimized to ensure smooth gas passage to maintain a low system pressure drop (reducing fan energy consumption), while also allowing the airflow to form a mass transfer-friendly flow pattern (such as laminar or transitional flow) within the channels, promoting the diffusion of pollutant molecules to the catalyst surface.

[0057] The metal fiber felt has a porosity greater than 85% and a fiber diameter of 10-50 micrometers, allowing gas to penetrate the felt with extremely low resistance, enabling high-throughput processing. The finer fibers increase the specific surface area per unit volume, providing more interfaces for catalyst loading and reaction. The network formed by these micrometer-scale interwoven fibers has a complex and varied pore structure, effectively disturbing the airflow, breaking the laminar boundary layer, and introducing turbulence effects at the microscale, thereby enhancing the mass transfer process of pollutants from the bulk gas phase to the catalyst layer on the fiber surface.

[0058] Yellow phosphorus exhaust gas is a complex gas-solid multiphase flow containing dust, aerosol precursors, and various polar molecules (such as PH3 and H2S). Fine particulate matter, some aerosols, or paramagnetic substances (such as certain iron- and manganese-containing dust particles) carried in the exhaust gas are subjected to a magnetic gradient force proportional to their magnetic susceptibility and volume in a non-uniform strong magnetic field. Since this force points towards the region of increased magnetic field strength, it drives these particles to migrate and aggregate towards the pipe wall or specific high-intensity areas, thereby promoting collisions between small particles and their agglomeration into larger particles—a phenomenon known as magnetoagglomeration.

[0059] In one embodiment provided in this disclosure, the magnetization pretreatment unit includes at least one tubular magnetizer 1. A non-uniform strong magnetic field is formed within the magnetizer 1, the direction of which is perpendicular to the exhaust gas flow direction or forms an angle of 45°-90° with the magnetic field. Yellow phosphorus exhaust gas flows into the tubular magnetizer 1 along a pipe. Within the magnetizer 1 section, the gas and the pollutants it carries are continuously exposed to a non-uniform strong magnetic field perpendicular to or intersecting the gas flow direction at a large angle. During the brief time the pollutants flow through the magnetic field, they are continuously subjected to the aforementioned magnetic force. Paramagnetic particles move towards the high field strength region and collide and aggregate under the drive of the magnetic field gradient force; polar molecules undergo dynamic magnetization and orientation processes under the influence of the magnetic field. After magnetic field pretreatment, the particle size distribution of some small particles in the exhaust gas shifts towards larger sizes, and the physicochemical state of some gaseous pollutants may be pre-activated. Subsequently, this magnetized exhaust gas is transported to a downstream deep catalytic oxidation unit for further treatment.

[0060] By arranging a non-uniform strong magnetic field at a large angle (especially perpendicular) to the airflow direction, the component of the magnetic field gradient force perpendicular to the airflow direction can be maximized. This effectively drives the migration and collision of particulate matter across the streamline direction, promotes the aggregation and growth of submicron fine particles and aerosol precursors, making them easier to be captured by subsequent inertial separation, interception or catalytic bed, reducing the risk of downstream units being blocked by ultrafine particles, and improving the particulate matter removal efficiency of the overall system.

[0061] The magnetic field is angled between 45° and 90° with the airflow direction, ensuring that the velocity vector of pollutant molecules and particles moving along the pipe is not parallel to the direction of the magnetic field lines. This increases the rate at which charge or magnetic moment cuts the magnetic field lines, enhancing the dynamic effects such as Lorentz force and magnetic torque, thereby increasing the strength and probability of the magnetic field's effect on pollutants. By promoting particulate agglomeration, the magnetization pretreatment reduces the number concentration of particulate matter at the inlet of the downstream catalytic unit, especially the difficult-to-treat ultrafine particles, mitigating the risk of physical blockage and deactivation of the catalyst. Simultaneously, the potential pre-activation of polar molecules could theoretically lower the initiation temperature or increase the reaction rate of subsequent catalytic oxidation reactions, contributing to deeper purification and potentially reducing the overall energy consumption of the catalytic unit.

[0062] This disclosure utilizes a tubular magnetizer 1 from the prior art, which resembles a conventional pipe in shape and can be easily connected in series or parallel to existing exhaust gas pipeline systems without requiring large-scale modifications to the process flow. The design of the magnetic field direction being perpendicular to the pipe axis (airflow direction) or at a fixed large angle allows the magnetic field generating device (such as a permanent magnet array or electromagnetic coil) to be regularly arranged around the pipe section, resulting in a compact structure and relatively simple installation and maintenance.

[0063] Specifically, the magnetization pretreatment unit includes two magnetizers 1 connected in series, with the magnetic field directions within adjacent magnetizers 1 perpendicular to each other, thus providing the flowing pollutants with two orthogonal magnetic field treatments. After being subjected to a force in one direction (e.g., radially along the pipe axis) in the first-stage magnetic field, the pollutants immediately receive a force in another direction perpendicular to the first direction (e.g., circumferentially along the pipe axis) in the second-stage magnetic field. Particles driven to migrate laterally in the first-stage magnetic field are deflected upon entering the second-stage magnetic field due to the new, perpendicular magnetic force. This sudden change in direction increases the probability of non-directional collisions between particles and between particles and the pipe wall. Simultaneously, the initially agglomerated particle clusters exiting the first stage undergo shearing or rotation due to different forces when entering the second-stage magnetic field, which helps break up the loose structure, promotes tighter agglomeration, or causes small clusters to further collide and merge into larger clusters, thereby more effectively shifting the particle size distribution in the exhaust gas towards larger sizes that are easier to process laterally.

[0064] In this disclosure, the magnetic field is generated by electromagnetic coils wound in segments along the axial direction of the tubular magnetizer 1. Each segment of the coil can be independently controlled to form a magnetic field intensity gradient or pulsed magnetic field in the airflow direction. By axially segmenting the coils and independently controlling the current in each segment, a preset magnetic field intensity gradient distribution can be precisely constructed along the airflow path. For example, it can be set to a strong magnetic field at the inlet and a weaker magnetic field at the outlet, or vice versa. This gradient design can match the state changes of pollutants during the pretreatment process: using a strong magnetic field at the inlet can apply the strongest capture and activation driving force to pollutants with high initial concentrations and different states, achieving rapid initialization; in subsequent sections, the magnetic field intensity is appropriately adjusted according to the partially agglomerated or activated state of the pollutants to maintain or complete the treatment process with optimal energy input. By configuring the corresponding magnetic field intensity in an on-demand manner, an optimal balance between treatment effect and energy consumption is achieved.

[0065] During the off or weak period of the pulsed magnetic field, the magnetic gradient force acting on the particles temporarily disappears or weakens, causing the aggregated particles that have been adsorbed by the magnetic field force near the pipe wall or coil to be partially carried away by the airflow shear force and enter the downstream unit. This prevents the excessive accumulation and blockage of particles in the pretreatment unit, keeps the flow channel unobstructed for a long time, and reduces maintenance requirements.

[0066] In one embodiment provided in this disclosure, the yellow phosphorus tail gas purification device further includes an aerosol condensation separator 3 located downstream of the deep catalytic oxidation unit; the aerosol condensation separator 3 is provided with a plurality of condensation plates 31 arranged in a herringbone or wave-shaped array, the surface of the condensation plates 31 is provided with a hydrophobic and oleophobic coating and / or raised texture 32, and the plate surface of the condensation plates 31 forms an acute angle with the horizontal air intake direction.

[0067] In the exhaust gas after deep catalytic oxidation, gaseous pollutants are converted into corresponding acid anhydrides, which readily condense into submicron-sized aerosol particles during cooling, making them difficult to remove effectively using traditional methods. When the airflow carrying aerosol particles enters the separator horizontally and flows through the array of condensation plates 31 arranged at an acute angle to the airflow, the airflow direction is forced to deflect multiple times. Larger aerosol particles, due to their greater inertia, cannot keep up with the abrupt changes in airflow direction, thus deviating from the streamline and directly impacting the inclined plate surface—this is the first stage of trapping. Tiny droplets or particles impacting the plate surface are not easily spread and wetted on the hydrophobic and oleophobic coating, tending to remain spherical and slide along the plate surface. During sliding, they are more likely to collide and merge (agglomerate) with other impacting particles, forming larger droplets. The raised texture 32 on the plate surface further disturbs the thin layer of airflow close to the plate surface, increasing the local turbulence and collision probability of particles, thereby helping droplets to aggregate more quickly.

[0068] The herringbone or wave-shaped array arrangement forms a continuous, tortuous, narrow flow channel. As the airflow passes through, its speed and direction constantly change, generating a series of vortices and acceleration zones. This allows particles of different sizes to have more opportunities to be thrown towards the plate surface due to inertia or centrifugal force at different positions, thus extending the effective residence time of the particles within the separator.

[0069] The exhaust gas containing secondary aerosols enters horizontally into the aerosol condenser separator 3. The gas first impacts the first row of inclined condensation plates 31, directly capturing some larger particles. The gas flow then splits, meandering through a herringbone or wavy channel formed by multiple condensation plates 31. Within this channel network, aerosol particles continuously undergo acceleration, deceleration, and changes in direction, constantly impacting the plate surfaces due to inertia. On the plate surfaces, the hydrophobic and oleophobic surfaces promote droplet coalescence, and the raised texture 32 enhances the disturbance, causing small droplets to rapidly merge into larger droplets sufficient to overcome the airflow drag and surface adhesion. These large droplets flow downwards along the inclined plate surfaces under gravity, eventually converging into a collection tank at the bottom of the separator. The purified gas is then discharged from the other end of the separator, thus completing the efficient removal of aerosols.

[0070] Through inertial collisions induced by the sharp-angled plate surface, multi-stage separation opportunities provided by the arrayed flow channels, and the aggregation effect promoted by surface treatment, this structure can efficiently capture submicron-sized aerosol particles that are difficult for traditional demisters to handle, reducing the emission concentration of total particulate matter and acid mist in the exhaust gas. The hydrophobic and oleophobic coating prevents the plate surface from being wetted and adhered to by sticky acid mist or solid particles, keeping the plate surface clean and allowing accumulated droplets to slide off smoothly, preventing plate clogging and scaling. Combined with the boundary layer disturbance caused by the raised texture 32, the possibility of solid deposition is further reduced, enabling the separator to operate for extended periods under high aerosol loads without frequent flushing, reducing maintenance frequency and costs.

[0071] In this disclosure, the magnetization pretreatment unit and the deep catalytic oxidation unit are integrated within the same housing 4, with the magnetizer 1 located at the inlet end of the electrothermal catalytic reactor. This eliminates the need for connecting pipes, supporting structures, and additional insulation layers between the two independent units, significantly reducing the equipment's footprint, steel consumption, and installation workload. Simultaneously, it shortens the exhaust gas flow path within the entire device, reducing flow resistance losses and helping to lower the overall system pressure drop. In this case, a smaller induced draft fan (to aid exhaust gas flow, as is common knowledge) can be selected, thereby reducing energy consumption.

[0072] Furthermore, the exhaust gas pretreated with a magnetic field can directly enter the catalytic reaction zone without passing through any external pipelines, thus preserving the activation effect of the magnetization pretreatment. The potential conformational changes of polar molecules or the agglomeration of particulate matter caused by the magnetic field may relax over time or under changing conditions. Direct introduction into the high-temperature catalytic environment allows the activated pollutant molecules to fully contact and react with the catalytically active sites, improving the utilization rate of the magnetization effect and strengthening the synergistic effect between pretreatment and main treatment.

[0073] The yellow phosphorus tail gas purification device also includes a controller and a concentration detector. The concentration detector is used to detect the pollutant concentration information at the air inlet of the deep catalytic oxidation unit. The controller is connected to the power supply of the concentration detector and the electrothermal catalytic grid 2, and is used to dynamically adjust the input power of the electrothermal catalytic grid 2 according to the pollutant concentration information.

[0074] A concentration detector at the inlet of the catalytic unit can acquire real-time concentration signals of key pollutants (such as pH3, total phosphorus, or particulate matter) in the exhaust gas about to enter the reactor. The controller uses this concentration signal (usually combined with a preset or measured flow rate signal) as a core input parameter. Through built-in control algorithms (such as PID control, fuzzy control, or model-based predictive control), it calculates and makes decisions, dynamically sending adjustment commands to the power supply of the electrothermal catalytic grid 2, changing its output voltage, current, or duty cycle. This precisely and quickly adjusts the total input power of the electrothermal catalytic grid 2, ultimately achieving precise control of the catalytic grid's operating temperature. In this way, the catalytic grid temperature can always automatically track and match the optimal reaction temperature required by the current pollutant load, ensuring that purification efficiency meets standards while avoiding unnecessary excessive energy consumption.

[0075] After the yellow phosphorus tail gas purification device is started, the control system immediately begins operation. Concentration detectors continuously monitor the tail gas entering the deep catalytic oxidation unit online and transmit real-time pollutant concentration data to the controller. The controller compares and calculates the received concentration data with internally set target concentration thresholds, temperature-load relationship models, and possible historical operating data. When an increase in inlet pollutant concentration is detected, the controller determines that the current input power (corresponding temperature) of the catalytic grid may be insufficient to efficiently handle the increased load. To prevent a decrease in purification efficiency, the controller immediately or at a preset rate increases the power output, raising the temperature of the electrothermal catalytic grid 2, enhancing its oxidation capacity, and ensuring that the outlet gas continuously meets standards. Conversely, when a decrease in inlet pollutant concentration is detected, the controller determines that the current power may exceed the necessary level. To avoid energy waste and potentially extend catalyst life, the controller gradually reduces the power output, allowing the catalytic grid to operate in a more energy-efficient temperature range while maintaining basic purification capacity. Throughout the operation, this adjustment is performed continuously or intermittently at high frequency, enabling the operating state of the electrothermal catalytic grid 2 to closely follow the tail gas load changes caused by fluctuations in the upstream process (yellow phosphorus production), forming a dynamic balance.

[0076] By employing a feedforward rapid response, power compensation is initiated the instantaneously upon an increase in pollutant concentration, allowing the catalytic grid temperature to rise in advance or synchronously. This effectively buffers load shocks, ensuring stable compliance with outlet concentration standards and enhancing the unit's resistance to shock loads and overall operational reliability. Avoiding unnecessary prolonged high-temperature operation reduces the accumulation of thermal stress and the rate of thermal aging in the catalytic grid. Simultaneously, stable power regulation (rather than frequent and abrupt start-stop cycles) helps protect the power supply equipment and catalytic grid structure. All of these factors contribute to extending the replacement cycle of core components and reducing maintenance frequency and costs. With process parameters (concentration) linked to equipment control (power), operators no longer need to make frequent manual adjustments based on experience, reducing reliance on human experience and the risk of operational errors. This also allows the unit to adapt more quickly to different operating conditions or changes in raw materials, ensuring safe and reliable tail gas purification. Furthermore, the inlet gas concentration data recorded by the concentration detector and the power regulation log recorded by the controller can be used to analyze the relationship between production conditions and purification performance, providing a basis for technicians to optimize control algorithms and improve processes.

[0077] In this disclosure, the concentration detectors are phosphine concentration sensors and / or particulate matter concentration sensors. The phosphine concentration sensor monitors the PH3 concentration at the catalytic unit inlet in real time, accurately reflecting the chemical oxidation load of the exhaust gas on the catalytic oxidation unit. Simultaneously, the particulate matter concentration sensor monitors the concentration of particulate matter (including soot, dust, and potentially formed phosphate microcrystals) in the exhaust gas. Adjusting the catalytic grid power accordingly can optimize the reaction temperature. For example, when the particulate matter concentration is abnormally high, moderately increasing the temperature may help ablate some volatile components or maintain catalyst surface activity, thereby alleviating blockage to some extent.

[0078] In this disclosure, the yellow phosphorus tail gas purification device also includes a terminal, to which the controller is communicatively connected. This allows the user to view purification process parameters and status via the terminal, and also to issue commands through the controller to adjust the corresponding process parameters. Specifically, the terminal is configured as a laptop, tablet, mobile phone, or other device with input capabilities; this disclosure does not impose any limitations on this.

[0079] In this disclosure, the controller is configured as a central processing unit (CPU). Furthermore, the controller is integrated into the terminal. Of course, in other embodiments, the controller may also be configured as a PLC logic controller and located elsewhere besides the terminal.

[0080] Alternatively, the controller can be configured as a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or a field-programmable gate array (FPGA).

[0081] In this disclosure, the controller is communicatively connected to various sensors via cables. In other embodiments, the controller may also be connected to the sensors via wireless communication modules such as Wi-Fi or ZigBee modules. Those skilled in the art can flexibly configure the controller based on the concept of this disclosure.

[0082] In addition, it should be noted that the tubular magnetizer 1, various sensors and controllers are all existing technologies. Those skilled in the art can make conventional improvements to the above-mentioned devices or components under the technical concept of this disclosure, and this disclosure does not impose any restrictions on them.

[0083] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0084] Finally, it should be noted that this invention is not limited to the optional embodiments described above, and anyone can derive other various forms of products under the guidance of this invention. The specific embodiments described above should not be construed as limiting the scope of protection of this invention, which should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A yellow phosphorus tail gas purification device, characterized in that, It includes a magnetization pretreatment unit and a deep catalytic oxidation unit that are arranged sequentially and connected along the exhaust gas flow direction; The deep catalytic oxidation unit includes an electrothermal catalytic reactor, which has multiple layers of spaced electrothermal catalytic mesh inside. The electrothermal catalytic mesh is perpendicular to the exhaust gas flow direction, and the layers of electrothermal catalytic mesh are electrically connected through a conductive structure. The electrothermal catalytic network includes a conductive substrate and a catalytically active material layer supported on its surface. The conductive substrate is a metal honeycomb or metal fiber felt. The catalytically active material layer is a gradient loading structure along the airflow direction, wherein the loading amount of the active component gradually increases or the types of active components change according to the oxidation capacity gradient. The active component of the catalytically active material layer is a transition metal oxide, and the support is an active alumina coating. The magnetization pretreatment unit includes at least one stage of tubular magnetizer, in which a non-uniform strong magnetic field is formed. The magnetic field is generated by electromagnetic coils wound in segments along the axial direction of the tubular magnetizer. Each segment of the coil can be controlled independently to form a magnetic field intensity gradient or pulsed magnetic field in the direction of airflow. The direction of the magnetic field is perpendicular to the direction of exhaust airflow or at an angle of 45°-90°. The magnetization pretreatment unit includes two magnetizers connected in series, and the magnetic field directions in adjacent magnetizers are perpendicular to each other.

2. The yellow phosphorus tail gas purification device according to claim 1, characterized in that, The metal honeycomb has a pore density of 100-400 mesh, and the metal fiber felt has a porosity greater than 85% and a fiber diameter of 10-50 micrometers.

3. The yellow phosphorus tail gas purification device according to claim 1, characterized in that, The yellow phosphorus tail gas purification device also includes an aerosol condensation separator located downstream of the deep catalytic oxidation unit; the aerosol condensation separator is provided with multiple condensation plates arranged in a herringbone or wave-shaped array, the surface of the condensation plates is provided with a hydrophobic and oleophobic coating and / or raised texture, and the plate surface of the condensation plate forms an acute angle with the horizontal air intake direction.

4. The yellow phosphorus tail gas purification device according to claim 1, characterized in that, The magnetization pretreatment unit and the deep catalytic oxidation unit are integrated in the same housing, and the magnetizer is located at the gas inlet end of the electrothermal catalytic reactor.

5. The yellow phosphorus tail gas purification device according to any one of claims 1-4, characterized in that, The yellow phosphorus tail gas purification device also includes a controller and a concentration detector. The concentration detector is used to detect the pollutant concentration information at the air inlet of the deep catalytic oxidation unit. The controller is connected in communication with the power supply of the concentration detector and the electrothermal catalytic grid, and is used to dynamically adjust the input power of the electrothermal catalytic grid according to the pollutant concentration information.

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