Three-phase synergic trapping pre-purification equipment for industrial waste gas nitric acid mist

Abstract

The present application relates to the technical field of filtering and purifying equipment, and discloses a three-phase synergistic capture pre-purification equipment for industrial waste gas nitric acid mist, which comprises a purification tank, a pretreatment unit, a capture unit, an interference elimination unit and a sample adaptation unit and other components, and aims to solve the problem of low capture efficiency of aerosol nitrate with small particle size and strong dispersibility in flue gas in the prior art, which leads to inaccurate monitoring results, wherein the capture unit is combined with a constant-temperature immersion filter membrane through a three-stage tapered impact plate to realize efficient inertial impact and absorption of aerosols with different particle sizes; the interference elimination unit can target removal of interference substances such as VOCs and carbonate; and the sample adaptation unit can automatically complete dilution, pH adjustment and filtration, the whole device is modularized and corrosion-resistant, can efficiently capture nitric acid mist and remove interference, and makes the pretreated sample directly into the ion chromatograph, thereby significantly improving the accuracy, automation degree and operation stability of nitric acid mist monitoring in complex flue gas matrix.

Description

Technical Field

[0001] This invention relates to the field of filtration and purification equipment technology, and in particular to a pre-purification equipment for the three-phase synergistic capture of nitric acid mist in industrial waste gas. Background Technology

[0002] Nitric acid mist, a typical pollutant in industrial flue gas, is widely generated in industrial production processes such as metal smelting, electronic etching, and chemical synthesis. Its main components include gaseous nitric acid, nitric acid droplets, and aerosol nitrates. This type of pollutant is both highly corrosive and biotoxic, causing severe corrosion to industrial equipment, disrupting the ecological balance, and harming human respiratory health. Therefore, accurate monitoring and efficient treatment of nitric acid mist has become a key issue in industrial flue gas purification. In the field of environmental monitoring of nitric acid mist in industrial waste gas, various pretreatment technologies have been developed to meet the needs of different monitoring scenarios. Among these methods, absorption, a widely used traditional approach, typically combines a spray tower with an absorbent such as sodium hydroxide to remove nitric acid mist from flue gas through acid-base neutralization. Filtration relies mainly on media such as quartz membranes to physically trap dust-laden flue gas, thereby separating particulate matter and some liquid nitric acid mist. Electrostatic capture technology uses a high-voltage electric field to charge aerosol particles and capture them under the influence of the electric field, showing particular advantages in treating fine particulate matter. In addition, combinations of absorption, filtration, or electrostatic technologies are often used in practice to form a combined treatment process, comprehensively improving the pretreatment effect and providing a sample basis for subsequent environmental monitoring and analysis.

[0003] Regarding the above and existing related technologies, the inventors believe that the following defects often exist: the existing purification equipment has low efficiency in capturing aerosol nitrates: the aerosol nitrate particles in complex flue gas are small in size and highly dispersed, making it difficult for traditional single technologies to achieve efficient capture, resulting in low monitoring results. Summary of the Invention

[0004] The technical problem to be solved by this invention is that the existing technology has the disadvantage that traditional purification equipment is difficult to effectively capture aerosol nitrate with small particle size and strong dispersion, resulting in significantly lower environmental detection results. To this end, we propose a three-phase synergistic capture and pre-purification equipment for industrial waste gas nitrate mist.

[0005] To achieve the above objectives, this application adopts the following technical solution: a pre-purification device for three-phase synergistic capture of nitric acid mist in industrial waste gas, including a purification box and an inspection port opened on the top of the purification box. The top of the inspection port is covered with a sealing cover. Inside the purification box, a pretreatment unit, a capture unit, and an interference elimination unit are arranged in sequence. The capture unit is used to capture aerosol nitrates in the waste gas. The interference elimination unit is used to eliminate the interference of nitrate ions in the sample during ion chromatography detection. An exhaust pipe is fixedly connected to the outer wall of the exhaust port of the purification box. An exhaust fan is installed at the inlet end of the exhaust pipe. A sample adaptation unit is connected to the end of the exhaust pipe. The sample adaptation unit is used to adjust and process the sample. The processed sample directly enters the ion chromatograph through the injection valve. The pretreatment unit includes a filter membrane support and a quartz fiber filter membrane fixedly connected to the inner wall of the filter membrane support. A preheater is fixedly connected to the outer wall of the filter membrane support near the air inlet of the inspection port. A fixed frame is provided on the outer wall of the other side of the filter membrane support. A granular activated carbon filter plate is fixedly connected to the inner wall of the fixed frame. An inner groove is opened at the adjacent edge of the top of the filter membrane support and the fixed frame. A connector is fixed in the inner groove. The filter membrane support and the fixed frame are detachably connected by the connector. A fastener is fixedly connected to the bottom of the outer wall of the fixed frame away from the filter membrane support. Positioning pins are fixedly connected to both sides of the bottom of the filter membrane support on the same side as the preheater. Positioning holes are opened on the bottom plate of the purification box corresponding to the positioning pins.

[0006] Preferably, the granular activated carbon filter plate has a hollow structure, and micro-pores are evenly opened on the two side walls corresponding to the air inlet of the purification box. The interior of the granular activated carbon filter plate is filled with granular activated carbon that has been impregnated and modified with 1.0 mol / L sodium carbonate. The activated carbon particle size is 2-3 mm and the specific surface area is ≥1000 m² / g.

[0007] Preferably, the connector includes a positioning shaft and a rotating cylinder movably sleeved on the outer wall of the positioning shaft. A connecting rod is fixedly connected to the side wall of the rotating cylinder. The end of the connecting rod is movably engaged with a limiting cylinder. The limiting cylinder has a hollow cylindrical structure. An opening is provided on one side wall of the limiting cylinder to engage the end of the connecting rod. The positioning shaft and the limiting cylinder are respectively fixedly connected to the filter membrane support and the bottom plate of the inner groove at the top of the fixed frame.

[0008] Preferably, the fastener includes a fixed plate fixedly connected to the bottom edges of the side wall of the fixed frame and a rotating rod rotatably connected between the side walls of the fixed plate. A positioning cylinder is fixedly connected to the opposite side wall of the fixed plate. The rotating rod is movably connected through the positioning cylinder. A spring is fixedly connected to the outer wall of the rotating rod inside the positioning cylinder. Arc-shaped rods are fixedly connected to the outer walls of the two ends of the rotating rod between the positioning cylinders. A limit rod is fixedly connected to the bottom plate of the purification box at the corresponding arc-shaped rod. A pull rope is wound on the outer wall of one end of the rotating rod. A limit plate is fixedly connected to the side wall at the top of the fixed frame above the pull rope. The top end of the pull rope is movably connected through the limit plate. The top end of the pull rope has a spherical structure.

[0009] Preferably, the arc-shaped rod has a G-shaped structure. When the spring is in a normally relaxed state, the end of the arc-shaped rod is located directly above the rotating rod. At this time, the arc-shaped rod is suspended within the semicircle formed by the top of the limiting rod.

[0010] Preferably, the collection unit includes three sets of spaced constant-temperature heating walls and connecting rods that penetrate the side walls at the four corners of the constant-temperature heating walls. Polytetrafluoroethylene (PTFE) filter membranes treated with sodium carbonate are fixedly attached to the outer walls of the three sets of constant-temperature heating walls near the air inlet of the purification box. A first-stage impact plate, a second-stage impact plate, and a third-stage impact plate are sequentially fixed and penetrated on the outer walls of the connecting rods on the outer sides of the three sets of PTFE filter membranes. Impact through holes are opened on the side walls of the first-stage, second-stage, and third-stage impact plates, and the inner diameter of the impact through holes on the first-stage, second-stage, and third-stage impact plates gradually decreases.

[0011] Preferably, the interference cancellation unit includes an outer frame fixedly connected to the inner wall of the purification chamber and a first mounting hole and a second mounting hole formed on the bottom plate of the outer frame. C is sequentially inserted into the first mounting hole and the second mounting hole, respectively. 18 Solid phase extraction column and soda lime packed column, C 18 Both the solid-phase extraction column and the soda-lime packed column extend to the top surface of the outer frame, and C 18 Both the solid phase extraction column and the soda lime packed column have handle grooves machined on the top.

[0012] Preferably, adjacent C 18 Solid-phase extraction columns are arranged side-by-side in close contact, and adjacent soda-lime packed columns are arranged side-by-side in close contact. C 18 Both the solid phase extraction column and the soda lime packed column have uniformly permeable pores on their shell sidewalls.

[0013] Preferably, the sample adapter unit includes a gas washing tank and a bracket fixedly connected to the side wall of the gas washing tank. The end of the suction pipe extends through the top plate of the gas washing tank and into its interior. Three sets of liquid storage tanks are fixedly connected to the top of the bracket. The three sets of liquid storage tanks respectively store deionized water, 0.1 mol / L sodium hydroxide solution and 0.1 mol / L hydrochloric acid solution. A peristaltic pump is fixedly connected to the top of each set of liquid storage tanks. A suction pipe is fixedly connected to the input end of the peristaltic pump. The end of the suction pipe extends through the inside of the liquid storage tank. An outlet pipe is fixedly connected to the output end of the peristaltic pump. The end of the outlet pipe extends through the top plate of the gas washing tank and into its interior. An outlet valve pipe is fixedly connected to the bottom of the gas washing tank. A filter box is fixedly installed at the inlet end of the outlet valve pipe. A polyethersulfone filter membrane is fixedly installed on the inner wall of the filter box.

[0014] Preferably, a PLC controller is fixedly connected to one side of the outer wall of the purification box, and buffer boxes are respectively provided on the bottom plate of the purification box adjacent to the pretreatment unit, the collection unit and the interference elimination unit. The buffer boxes are detachably connected to the purification box by bolts.

[0015] The technical effects and advantages of this invention are as follows: In this invention, a multi-stage synergistic purification process is constructed by integrating a pretreatment unit, a collection unit, an interference elimination unit, and a sample adaptation unit. This significantly improves the collection efficiency and anti-interference capability of aerosol nitrates. The pretreatment unit uses a combination of a quartz fiber filter membrane and a modified activated carbon filter plate to effectively trap particulate matter and adsorb acidic gases, creating favorable conditions for subsequent treatment. The collection unit combines a three-stage tapered impactor plate with a constant-temperature impregnated filter membrane to achieve efficient inertial impaction and surface absorption of aerosol nitrates of different particle sizes, overcoming the problem of low collection efficiency for small-particle aerosols. The interference elimination unit uses C... 18 Solid-phase extraction (SPE) columns and quicklime-packed columns target and remove VOCs and carbonate ions, ensuring sample suitability for ion chromatography analysis. The sample adaptation unit integrates online dilution, pH adjustment, and microfiltration functions, enabling automatic sample conditioning and direct injection, significantly reducing human error. The overall device features a modular structure, corrosion-resistant materials, and convenient maintenance. It can operate stably for extended periods in complex flue gas environments with high temperature and humidity, significantly improving the accuracy and precision of nitric acid mist monitoring and providing reliable pretreatment technology support for industrial flue gas purification and precision treatment. Attached Figure Description

[0016] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts: Figure 1 This is a schematic diagram of the overall structure of the pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas according to the present invention. Figure 2 This is a schematic diagram of the internal structure of the purification box of the pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas according to the present invention. Figure 3 This is a schematic cross-sectional view of the purification box of the pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas according to the present invention; Figure 4 This is a schematic diagram of the pretreatment unit structure of the pretreatment device for the three-phase synergistic capture and purification of nitric acid mist in industrial waste gas according to the present invention. Figure 5 An exploded view of the pretreatment unit of the industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification device of the present invention. Figure 6 The present invention relates to a pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas. Figure 4 Enlarged structural diagram at point A in the middle; Figure 7 This is a schematic diagram of the fixing structure of the pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas according to the present invention; Figure 8 This is a schematic diagram of the collection unit structure of the pre-purification device for the three-phase synergistic collection of nitric acid mist in industrial waste gas according to the present invention. Figure 9 This is a schematic diagram of the interference elimination unit structure of the pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas according to the present invention. Figure 10 This is a schematic diagram of the sample adaptation unit structure of the pre-purification device for the three-phase synergistic capture of nitric acid mist in industrial waste gas according to the present invention.

[0017] Legend: 1. Purification box; 11. Inspection port; 12. Sealing cover; 13. PLC controller; 14. Buffer box; 2. Pretreatment unit; 21. Filter membrane support; 22. Quartz fiber filter membrane; 23. Preheater; 24. Fixing frame; 25. Granular activated carbon filter plate; 26. Connector; 261. Positioning shaft; 262. Rotary drum; 263. Support rod; 264. Limiting cylinder; 27. Fixing component; 271. Fixing plate; 272. Rotary rod 273. Positioning cylinder; 274. Clock spring; 275. Arc rod; 276. Limiting rod; 277. Pull rope; 278. Limiting plate; 28. Positioning pin; 3. Collection unit; 31. Constant temperature heating wall; 32. Connecting rod; 33. Polytetrafluoroethylene filter membrane; 34. First-stage impact plate; 35. Second-stage impact plate; 36. Third-stage impact plate; 4. Interference cancellation unit; 41. Outer frame; 42. First mounting hole; 43. Second mounting hole; 44. C 18 45. Solid phase extraction column; 46. Soda lime packed column; 5. Handle groove; 6. Vacuum tube; 7. Vacuum fan; 8. Sample fitting unit; 9. Washing tank; 10. Bracket; 11. Liquid storage tank; 12. Peristaltic pump; 13. Liquid extraction tube; 14. Liquid outlet tube; 15. Liquid outlet valve tube; 16. Filter box. Detailed Implementation

[0018] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0019] Reference Figures 1-2As shown, this invention provides a technical solution: a pre-treatment device for the three-phase synergistic capture of nitric acid mist in industrial waste gas, comprising a purification chamber 1 and a support frame welded and fixed to the bottom of the purification chamber 1. The purification chamber 1 is a sealed cavity used to accommodate various treatment units, ensuring the airtightness and high efficiency of the waste gas treatment process. An inspection port 11 is provided on the top of the purification chamber 1, which facilitates the installation, inspection, maintenance, and replacement of the internal units. A sealing cover plate 12 is fixed to the top of the inspection port 11 by fixing bolts to ensure the airtightness of the equipment during operation and prevent waste gas leakage or external air intrusion that could affect the purification effect.

[0020] Inside the purification chamber 1, from the exhaust gas inlet (located to the left of the pretreatment unit) to the outlet, are arranged the pretreatment unit 2, the collection unit 3, and the interference elimination unit 4. This series design follows the logical sequence of exhaust gas treatment: first, preliminary purification and solid matter removal; then, droplet and aerosol collection; and finally, enrichment of the target component and elimination of interfering substances. The collection unit 3 is specifically designed for the efficient collection of aerosol nitrates in the exhaust gas, one of the main forms of nitrate mist. The interference elimination unit 4 addresses the needs of subsequent ion chromatography detection, eliminating various substances in the sample that may interfere with the detection of nitrate ions, ensuring the accuracy of the detection results.

[0021] An extraction pipe 5 is fixedly connected to the outer wall of the outlet of the purification chamber 1 to discharge the treated clean gas from the purification chamber 1. An extraction fan 6 is installed at the inlet end of the extraction pipe 5. The function of the extraction fan 6 is to provide power to draw the industrial waste gas into the purification chamber 1 and pass it sequentially through each treatment unit, maintaining negative pressure inside the system to ensure smooth flow of the waste gas and achieve the expected treatment efficiency. A sample adaptation unit 7 is connected to the end of the extraction pipe 5. This unit is used to further adjust the sample after capture and interference elimination, such as dilution and pH adjustment, to meet the injection requirements of the ion chromatograph. The treated sample will be directly injected into the ion chromatograph for analysis through the injection valve. This design integrates sampling, purification, pretreatment, and sample adaptation, greatly improving the convenience and automation of nitric acid mist detection in waste gas.

[0022] Furthermore, referring to Figures 1-5The pretreatment unit 2 is the first line of defense in the purification equipment, mainly used to remove coarse particulate matter from the waste gas and separate gaseous nitric acid. It includes a filter membrane support 21 and a quartz fiber filter membrane 22 fixedly connected to the inner wall of the filter membrane support 21. The quartz fiber filter membrane 22 has excellent high-temperature resistance and chemical stability, effectively capturing solid particulate matter in the waste gas while exhibiting low adsorption of gaseous nitric acid, thus achieving preliminary separation of gaseous nitric acid from particulate matter. A preheater 23 is fixedly connected to the outer wall of the filter membrane support 21 near the air inlet of the inspection port 11. The preheater 23 is crucial, as it heats the incoming waste gas to 5-10°C above the dew point (temperature controllable accuracy ±1°C), preventing water vapor in the waste gas from condensing on the quartz fiber filter membrane 22 and affecting its filtration efficiency. More importantly, heating inhibits the condensation and adsorption of gaseous nitric acid on the filter membrane, ensuring that gaseous nitric acid can pass smoothly through the quartz fiber filter membrane 22 and enter the subsequent granular activated carbon filter plate 25 for collection. This avoids additional errors caused by the reaction or adsorption of gaseous nitric acid on solid particles. A fixed frame 24 is provided on the outer wall of the other side of the filter membrane support 21. This fixed frame 24, together with the filter membrane support 21, constitutes the main structure of the pretreatment unit. Granular activated carbon filter plates 25 are fixedly connected to the inner walls of the fixed frame 24. The granular activated carbon filter plates 25 are used to adsorb the gaseous nitric acid after passing through the quartz fiber filter membrane 22, converting it into nitrates for collection.

[0023] To facilitate maintenance and replacement of the quartz fiber filter membrane 22 and the granular activated carbon filter plate 25, an inner groove is provided at the adjacent edges of the top of the filter membrane support 21 and the fixed frame 24, and a connector 26 is fixed in the inner groove. Through the connector 26, the filter membrane support 21 and the fixed frame 24 can be detachably connected, which greatly improves the maintenance convenience of the pretreatment unit.

[0024] A fixing member 27 is fixedly connected to the bottom of the outer wall of the fixed frame 24 on the side away from the filter membrane support 21. This fixing member 27 is used to stably fix the pretreatment unit 2 inside the purification chamber 1, preventing it from shifting or vibrating during equipment operation. Positioning pins 28 are fixedly connected to both sides of the bottom of the filter membrane support 21 on the same side as the preheater 23. Positioning holes are provided on the bottom plate of the purification chamber 1 corresponding to the positioning pins 28. The cooperation between the positioning pins 28 and the positioning holes further ensures the precise installation and stable positioning of the pretreatment unit 2 inside the purification chamber 1.

[0025] In a preferred embodiment, the granular activated carbon filter plate 25 has a hollow structure, which increases the contact area between the adsorption medium and the waste gas. Micropores are uniformly formed on the side walls at both ends corresponding to the air inlet of the purification chamber 1. These micropores ensure that the waste gas can uniformly enter the interior of the activated carbon filter plate, improving adsorption efficiency. The interior of the granular activated carbon filter plate 25 is filled with granular activated carbon modified by impregnation with 1.0 mol / L sodium carbonate. Sodium carbonate impregnation modification significantly enhances the adsorption capacity of activated carbon for acidic gases, especially the collection efficiency for gaseous nitric acid. As an alkaline substance, sodium carbonate can react with acidic nitric acid, fixing it on the surface of the activated carbon to form stable nitrates, thereby achieving efficient collection. Preferably, the activated carbon particle size is 2-3 mm, and the specific surface area is ≥1000 m² / g. Such particle size and specific surface area ensure that the activated carbon has sufficient adsorption capacity and low flow resistance, while avoiding dust problems caused by excessively small particles. Modified activated carbon removes acidic gases such as SO2 through a dual process of "physical adsorption + chemical adsorption": physical adsorption relies on its high specific surface area to achieve initial SO2 interception, while chemical adsorption involves the reaction of surface-loaded sodium carbonate with SO2 (SO2 + Na2CO3 = Na2SO3 + CO2↑), converting the acidic interference into stable salts and preventing it from competing with nitric acid mist for absorption sites in subsequent units. In a preferred embodiment, refer to Figures 4-6 The connector 26 includes a positioning shaft 261 and a rotating cylinder 262 movably sleeved on the outer wall of the positioning shaft 261. The positioning shaft 261 provides a center of rotation around which the rotating cylinder 262 rotates. A connecting rod 263 is fixedly connected to the side wall of the rotating cylinder 262, serving as the connecting actuator. The end of the connecting rod 263 movably engages with a limiting cylinder 264, providing a reliable engaging structure. The limiting cylinder 264 has a hollow cylindrical structure, with an opening on one end of its side wall to engage the end of the connecting rod 263. This structure allows the connecting rod 263 to flexibly enter and lock. The positioning shaft 261 and the limiting cylinder 264 are respectively fixedly connected to the filter membrane support 21 and the bottom plate of the inner groove at the top of the fixed frame 24. By rotating the rotating drum 262, the mounting rod 263 can be disengaged from or inserted into the limiting cylinder 264, thereby enabling the quick disassembly and installation of the filter membrane support 21 and the fixed frame 24, which greatly improves the efficiency and convenience of component replacement.

[0026] In a preferred embodiment, refer to Figures 2-7The fixing component 27 includes a fixing plate 271 fixedly connected to the bottom edges of the sidewall of the fixing frame 24 and a rotating rod 272 rotatably connected between the sidewalls of the fixing plate 271. The fixing plate 271 provides stable support, while the rotating rod 272 is responsible for the locking function. A positioning cylinder 273 is fixedly connected to the opposite sidewall of the fixing plate 271, and the rotating rod 272 is movably inserted through the positioning cylinder 273, which guides and supports the rotating rod 272. A spring-loaded spring 274 is fixedly connected to the outer wall of the rotating rod 272 inside the positioning cylinder 273. The spring-loaded spring 274 provides restoring force, allowing the fixing component 27 to automatically reset or maintain a certain tension in the released state. Arc-shaped rods 275 are fixedly connected to the outer walls of the two ends of the rotating rod 272 between the positioning cylinders 273, and the arc-shaped rods 275 are the key structure for achieving the locking function. A limiting rod 276 is fixedly connected to the bottom plate of the purification chamber 1 at the corresponding position of the arc-shaped rod 275. The limiting rod 276 cooperates with the arc-shaped rod 275 for locking. A pull rope 277 is wound on the outer wall of one end of the rotating rod 272. The pull rope 277 is used to manually operate the rotating rod 272. A limiting plate 278 is fixedly connected to the side wall at the top of the fixed frame 24 above the pull rope 277. The limiting plate 278 guides the pull rope 277. The top end of the pull rope 277 has a spherical structure, which is convenient for the operator to grasp and pull. When the pull rope 277 is pulled, the rotating rod 272 rotates, causing the arc-shaped rod 275 to disengage from the limiting rod 276, and the pretreatment unit 2 can be removed from the purification chamber 1. After the pull rope 277 is released, the spring 274 returns to its original position, and the arc-shaped rod 275 re-engages into the limiting rod 276, thereby achieving a firm fixation of the pretreatment unit.

[0027] In a preferred embodiment, refer to Figure 7 The curved rod 275 has a G-shaped structure. This unique shape design facilitates precise engagement and stable locking with the limiting rod 276. When the spring 274 is in its normally relaxed state, the end of the curved rod 275 is directly above the rotating rod 272. At this time, the curved rod 275 is suspended within the semi-circle formed by the top of the limiting rod 276, ensuring that the pretreatment unit 2 is firmly fixed to the bottom plate of the purification box 1. This G-shaped design, combined with the semi-circular top of the limiting rod 276, provides a stable engagement while also allowing the curved rod 275 to smoothly disengage when the pull rope 277 is pulled, balancing both stability and operability.

[0028] In a preferred embodiment, refer to Figure 2 and Figure 8The collection unit 3, located after the pretreatment unit 2, is primarily tasked with efficiently collecting aerosol nitrates from the exhaust gas. It comprises three sets of spaced-apart constant-temperature heating walls 31 and connecting rods 32 extending through the four corners of each wall. The constant-temperature heating walls 31 ensure the collection process operates under stable temperature conditions, preventing sample condensation or evaporation, thereby improving collection efficiency and accuracy. The connecting rods 32 are used to fix and support the constant-temperature heating walls 31 and the subsequent impact plate. On the outer wall of the three sets of constant-temperature heating walls near the air inlet of the purification chamber 1 (i.e., upstream of the exhaust flow), polytetrafluoroethylene (PTFE) filter membranes 33, treated with sodium carbonate, are fixed and adhered. PTFE filter membranes possess excellent chemical inertness, resisting corrosion from acidic gases. Sodium carbonate impregnation further enhances the membrane's ability to collect aerosol nitrates, especially when aerosols collide with the membrane surface; sodium carbonate forms stable compounds with nitrate ions, fixing them onto the membrane for enrichment. Three sets of polytetrafluoroethylene (PTFE) filter membranes 33 are connected by connecting rods 32 on their outer walls (i.e., downstream of the exhaust flow). A primary impact plate 34, a secondary impact plate 35, and a tertiary impact plate 36 are sequentially fixed and penetrated on the outer wall. This multi-stage impact plate design is a classic method for capturing aerosols based on the principle of inertial impaction. When exhaust gas containing aerosols passes through the small holes on the impact plates at high speed, the abrupt change in airflow direction, coupled with the inertia of the aerosol particles, prevents them from changing direction with the airflow. The aerosol particles then collide with the back of the impact plates or the filter membranes on them and are captured. Impact through-holes are provided on the side walls of the primary impact plate 34, secondary impact plate 35, and tertiary impact plate 36. The inner diameter of the impact through-holes on the primary impact plate 34, secondary impact plate 35, and tertiary impact plate 36 gradually decreases. This design, with apertures decreasing in size, gradually increases the gas flow rate, enabling the sequential capture of aerosol particles of different sizes. This achieves a wider range and higher efficiency in capturing aerosol nitrates, ensuring that nitrate particles of various sizes are effectively retained.

[0029] In a preferred embodiment, refer to Figure 2 and Figure 9 The interference cancellation unit 4 is located after the collection unit 3, and its core function is to remove impurities from the sample that may interfere with ion chromatography detection. It includes an outer frame 41 fixedly connected to the inner wall of the purification chamber 1. The outer frame 41 is used to house and position the key components for interference cancellation. The bottom plate of the outer frame 41 has a first mounting hole 42 and a second mounting hole 43, which are used to insert and fix different purification columns. C14 columns are sequentially inserted into the first mounting hole 42 and the second mounting hole 43, respectively. 18 Solid-phase extraction column 44 and quicklime packed column 45. C 18 Solid-phase extraction column 44 is mainly used to remove organic matter from samples. Many industrial waste gases contain complex organic components, which may co-elute with target ions or contaminate the chromatographic column during ion chromatography analysis.18 The column effectively traps these non-polar or weakly polar organic interferences (C) through hydrophobic interactions. 18 The packing material is a non-polar adsorbent, which can efficiently adsorb non-polar VOCs in flue gas, such as toluene, xylene, and acetone, through hydrophobic interactions. The soda-lime packed column 45 is mainly used to remove acidic gases (such as CO2, SO2, and HCl) from samples. Soda-lime (usually a mixture of calcium oxide and sodium hydroxide) is highly alkaline and can neutralize acidic gases. The reaction formula between soda-lime and CO2 is CaO + CO2 = CaCO3↓, removing it from the gas matrix (achieving deep removal of CO2 through physical interception, effectively avoiding interference from carbonate ions in the quantitative analysis of nitrate ions), thereby eliminating the potential interference of these acidic gases on the detection of nitrate ions. 18 Both the solid-phase extraction column 44 and the soda-lime packed column 45 extend through to the top surface of the outer frame 41, facilitating column installation and removal. Furthermore, C... 18 Both the solid-phase extraction column 44 and the soda-lime packed column 45 have handle grooves 46 machined on their tops. The handle grooves 46 further enhance operational convenience, making column replacement or maintenance easier. This two-column series combination achieves highly efficient removal of both organic matter and acidic gases, significantly improving the detection accuracy and reliability of ion chromatography. An online VOCs monitor is installed on the inner wall of the outlet end of the purification chamber 1. When the adsorption capacity is saturated (as indicated by an online VOCs monitor), the chamber can be quickly replaced to ensure stable interference removal.

[0030] In a preferred embodiment, adjacent C 18 Solid-phase extraction columns 44 are arranged side-by-side in a tightly fitted configuration, as are adjacent soda-lime packed columns 45. This close-fitting arrangement facilitates space utilization, resulting in a more compact equipment structure, while ensuring efficient airflow through all columns. 18 Both the solid-phase extraction column 44 and the soda-lime packed column 45 have uniformly distributed vent holes on their shell sidewalls. The design of these vent holes is crucial, ensuring that the exhaust gas can fully and uniformly contact the packing material within the column, improving adsorption and removal efficiency while preventing localized airflow short-circuiting or excessive flow resistance. These vent holes are typically fitted with precision filters or microporous membranes to prevent the packing material from escaping.

[0031] In a preferred embodiment, refer to Figure 1 and Figure 10The sample adaptation unit 7 is the final link in the entire purification equipment chain. It converts the purified gas, containing the nitrate ions or their derivatives to be detected, into a liquid sample suitable for injection into the ion chromatograph. It includes a gas washing tank 71 and a bracket 72 fixedly connected to the side wall of the gas washing tank 71. An exhaust valve and pressure gauge are installed on the top of the gas washing tank 71. The gas washing tank 71 serves as the core container for liquid absorption processing. The exhaust pipe 5 extends into the interior of the gas washing tank 71 after penetrating its top plate, allowing the exhaust gas, after pre-purification and interference elimination, to enter the gas washing tank 71 and fully contact the absorption liquid, transferring the gaseous or aerosol nitrate ions into the liquid phase. Three sets of liquid storage tanks 73 are fixedly connected to the top of the bracket 72. These liquid storage tanks 73 store various reagents used for sample conditioning. The three sets of liquid storage tanks 73 respectively store deionized water, 0.1 mol / L sodium hydroxide solution, and 0.1 mol / L hydrochloric acid solution. Deionized water can be used to dilute high-concentration samples, 0.1 mol / L sodium hydroxide solution can be used to increase the sample pH or neutralize acidity, and 0.1 mol / L hydrochloric acid solution can be used to decrease the sample pH or neutralize alkalinity. By providing these commonly used reagents, flexible adjustment of sample pH and concentration can be achieved to meet the requirements of the ion chromatograph. Each reservoir 73 is fixedly connected to a peristaltic pump 74 at its top. The peristaltic pump 74 is a pump with precise flow control, suitable for conveying various liquids. A suction pipe 75 is fixedly connected to the inlet of the peristaltic pump 74, extending into the reservoir 73 to precisely draw the required reagent from it. An outlet pipe 76 is fixedly connected to the outlet of the peristaltic pump 74, extending through the top plate of the gas washing tank 71 and into it, adding the drawn reagent to the gas washing tank 71 for mixing with the absorbed sample, for dilution or pH adjustment. A liquid outlet valve pipe 77 is fixedly connected to the bottom of the gas washing tank 71. The liquid outlet valve pipe 77 is used to discharge the processed liquid sample and send it to the ion chromatograph. A filter box 78 is fixedly installed at the inlet end of the liquid outlet valve pipe 77, and a polyethersulfone filter membrane is fixedly installed on the inner wall of the filter box 78. The polyethersulfone filter membrane has excellent chemical stability and filtration accuracy, which can effectively remove small particulate matter in the liquid sample, prevent it from clogging the sample injection system or chromatographic column of the ion chromatograph, and ensure the smooth progress of the analysis process and the accuracy of the results. The entire sample adaptation unit 7 is automatically controlled by a PLC controller 13. It can automatically adjust the reagent addition amount according to a preset program or according to the real-time monitored sample parameters (such as pH value and conductivity), realize automatic sample dilution and neutralization, minimize human operation error, and improve analytical efficiency.

[0032] In a preferred embodiment, refer to Figure 1 and Figure 3A PLC controller 13 is fixedly connected to the outer wall of one side of the purification chamber 1. The PLC controller 13 (Programmable Logic Controller) is the "brain" of the entire equipment, responsible for centralized control and management of various operating parameters and workflows of the equipment, such as the temperature of the preheater 23, the speed of the exhaust fan 6, the flow rate of the peristaltic pump 74, and the temperature of the constant temperature heating wall 31. Through the PLC controller 13, users can program and monitor the equipment to achieve automated operation, fault diagnosis, and parameter adjustment, greatly improving the intelligence and automation level of the equipment. Buffer boxes 14 are respectively installed on the bottom plate of the purification chamber 1 adjacent to the pretreatment unit 2, the collection unit 3, and the interference elimination unit 4. Buffer boxes 14 are used to collect waste, condensate, or samples to be processed generated during the processing of each unit. For example, the buffer box 14 below the pretreatment unit 2 can collect particulate matter trapped by the quartz fiber filter membrane 22, the buffer box 14 below the collection unit 3 can collect droplets captured by the impact plate and nitrates on the filter membrane, and the buffer box 14 below the interference elimination unit 4 can collect absorbent liquid or condensate enriched with impurities. The buffer box 14 is detachably connected to the purification chamber 1 via bolts. This detachable connection allows the buffer box 14 to be easily pulled down or slid out for easy emptying, cleaning, or replacement, greatly simplifying daily maintenance and meeting environmental requirements for waste sorting. The buffer box 14 is typically designed as an airtight container to prevent secondary contamination.

[0033] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A pre-treatment device for the three-phase synergistic capture of nitric acid mist in industrial waste gas, characterized in that, The purification chamber (1) includes a purification box (1) and an inspection port (11) on the top of the purification box (1). The top of the inspection port (11) is covered with a sealing cover plate (12). Inside the purification box (1), a pretreatment unit (2), a collection unit (3) and an interference elimination unit (4) are arranged in sequence. The collection unit (3) is used to collect aerosol nitrates in the exhaust gas. The interference elimination unit (4) is used to eliminate the interference of nitrate ions in the sample during ion chromatography detection. A suction pipe (5) is fixedly connected to the outer wall of the exhaust port of the purification box (1). A suction fan (6) is provided at the inlet end of the suction pipe (5). A sample adapter unit (7) is connected to the end of the suction pipe (5). The sample adapter unit (7) is used to adjust the sample. The processed sample directly enters the ion chromatograph through the injection valve. The pretreatment unit (2) includes a filter membrane support (21) and a quartz fiber filter membrane (22) fixedly connected to the inner wall of the filter membrane support (21). A preheater (23) is fixedly connected to the outer wall of the filter membrane support (21) near the air inlet of the inspection port (11). A fixed frame (24) is provided on the other outer wall of the filter membrane support (21). A granular activated carbon filter plate (25) is fixedly connected to the inner wall of the fixed frame (24). The filter membrane support (21) and the fixed frame (24) are topped together. An inner groove is provided at the adjacent edge of the part, and a connector (26) is fixed in the inner groove. The filter membrane support (21) and the fixed frame (24) are detachably connected by the connector (26). A fixing member (27) is fixedly connected to the bottom of the outer wall of the fixed frame (24) away from the filter membrane support (21). Positioning pins (28) are fixedly connected to the bottom sides of the filter membrane support (21) on the same side as the preheater (23). Positioning holes are provided on the bottom plate of the purification box (1) corresponding to the positioning pins (28).

2. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: The granular activated carbon filter plate (25) has a hollow structure, and micro-pores are evenly opened on the two side walls corresponding to the air inlet of the purification box (1). The granular activated carbon filter plate (25) is filled with granular activated carbon modified by impregnation with 1.0mol / L sodium carbonate. The activated carbon particle size is 2-3mm and the specific surface area is ≥1000m² / g.

3. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: The connector (26) includes a positioning shaft (261) and a rotating cylinder (262) movably sleeved on the outer wall of the positioning shaft (261). A connecting rod (263) is fixedly connected to the side wall of the rotating cylinder (262). The end of the connecting rod (263) is movably engaged with a limiting cylinder (264). The limiting cylinder (264) has a hollow cylindrical structure. An opening is provided on one side wall of the limiting cylinder (264) to engage the end of the connecting rod (263). The positioning shaft (261) and the limiting cylinder (264) are respectively fixedly connected to the filter membrane support (21) and the bottom plate of the inner groove at the top of the fixed frame (24).

4. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: The fastener (27) includes a fixed plate (271) fixedly connected to the bottom edges of the side wall of the fixed frame (24) and a rotating rod (272) rotatably connected between the side walls of the fixed plate (271). A positioning cylinder (273) is fixedly connected to the opposite side wall of the fixed plate (271). The rotating rod (272) is movably connected through the positioning cylinder (273). A spring spring (274) is fixedly connected to the outer wall of the rotating rod (272) inside the positioning cylinder (273). The rotating rod (272) between the positioning cylinders (273) is connected to the spring spring (274). Arc-shaped rods (275) are fixedly connected to the outer walls of both ends of the rod (272). A limiting rod (276) is fixedly connected to the bottom plate of the purification box (1) at the corresponding arc-shaped rod (275). A pull rope (277) is wound on the outer wall of one end of the rotating rod (272). A limiting plate (278) is fixedly connected to the side wall at the top of the fixed frame (24) above the pull rope (277). The top end of the pull rope (277) is movably connected through the limiting plate (278). The top end of the pull rope (277) has a spherical structure.

5. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 4, characterized in that: The arc-shaped rod (275) has a G-shaped structure. When the spring (274) is in a normal relaxed state, the end of the arc-shaped rod (275) is located directly above the rotating rod (272). At this time, the arc-shaped rod (275) is suspended in the semi-circle formed by the top of the limiting rod (276).

6. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: The collection unit (3) includes three sets of spaced constant temperature heating walls (31) and connecting rods (32) that penetrate the side walls at the four corners of the constant temperature heating walls (31). The outer walls of the three sets of constant temperature heating walls (31) near the air inlet of the purification box (1) are respectively fixed with polytetrafluoroethylene filter membranes (33) that have been impregnated with sodium carbonate. The outer walls of the connecting rods (32) on the outside of the three sets of polytetrafluoroethylene filter membranes (33) are sequentially fixed with a first-stage impact plate (34), a second-stage impact plate (35) and a third-stage impact plate (36). Impact through holes are opened on the side walls of the first-stage impact plate (34), the second-stage impact plate (35) and the third-stage impact plate (36). The inner diameter of the impact through holes on the first-stage impact plate (34), the second-stage impact plate (35) and the third-stage impact plate (36) gradually decreases.

7. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: The interference cancellation unit (4) includes an outer frame (41) fixedly connected to the inner wall of the purification box (1) and a first mounting hole (42) and a second mounting hole (43) opened on the bottom plate of the outer frame (41). C is inserted into the first mounting hole (42) and the second mounting hole (43) respectively. 18 Solid-phase extraction column (44) and quicklime packed column (45), wherein C 18 The tops of both the solid-phase extraction column (44) and the soda-lime packed column (45) extend through to the top surface of the outer frame (41), and C 18 Both the solid phase extraction column (44) and the soda lime packed column (45) have handle grooves (46) machined on their tops.

8. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 7, characterized in that: The adjacent C 18 Solid phase extraction columns (44) are arranged side by side in close contact, and adjacent soda-lime packed columns (45) are arranged side by side in close contact. 18 The solid phase extraction column (44) and the soda lime packed column (45) have uniformly permeable pores on their shell sidewalls.

9. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: The sample fitting unit (7) includes a gas washing tank (71) and a bracket (72) fixedly connected to the side wall of the gas washing tank (71). The end of the suction pipe (5) extends through the top plate of the gas washing tank (71) and into its interior. Three sets of liquid storage tanks (73) are fixedly connected to the top of the bracket (72). The three sets of liquid storage tanks (73) respectively store deionized water, 0.1 mol / L sodium hydroxide solution and 0.1 mol / L hydrochloric acid solution. A peristaltic pump (74) is fixedly connected to the top of each set of liquid storage tanks (73). The peristaltic pump (74) is fixedly connected to a liquid extraction pipe (75) at its input end. The end of the liquid extraction pipe (75) extends through the inside of the liquid storage tank (73). The peristaltic pump (74) is fixedly connected to an outlet pipe (76) at its output end. The end of the outlet pipe (76) extends through the top plate of the gas washing tank (71) and into its interior. The gas washing tank (71) is fixedly connected to an outlet valve pipe (77) at its bottom. A filter box (78) is fixedly installed at the inlet end of the outlet valve pipe (77). A polyethersulfone filter membrane is fixedly disposed on the inner wall of the filter box (78).

10. The industrial waste gas nitric acid mist three-phase synergistic capture and pre-purification equipment according to claim 1, characterized in that: A PLC controller (13) is fixedly connected to one side of the outer wall of the purification box (1). A buffer box (14) is respectively provided on the bottom plate of the purification box (1) adjacent to the pretreatment unit (2), the collection unit (3) and the interference elimination unit (4). The buffer box (14) is detachably connected to the purification box (1) by bolts.

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