A waste gas treatment device for boron acid production

Abstract

The utility model discloses a waste gas treatment device of boric acid production, including cloth bag dust collector main part, the output of cloth bag dust collector main part is assembled and is arranged into gas pipeline, the end of arranged into gas pipeline is assembled and is equipped with the fan, the end of arranged into gas pipeline is assembled and is equipped with the adapter pipe, the output of fan is assembled and is equipped with the communicating pipe, the adapter pipe and the communicating pipe between assembly have the filter seal cover, the inside center of filter seal cover is assembled and is equipped with the filter component, the bottom of cloth bag dust collector main part is assembled and is equipped with the dust outlet hopper, and this device adds filter seal cover and built -in filter component after cloth bag dust collector main part, forms " cloth bag primary filter + filter screen secondary filter " double filtration structure: the dust cloth bag in cloth bag dust collector first carries out the primary filtration to the big particle dust in waste gas, and the residual fine dust is further intercepted by the filter screen board inlayed in the filter ring in filter component after entering filter seal cover with waste gas, effectively reduces the particulate matter content in waste gas.

Description

Technical Field

[0001] This utility model relates to the field of waste gas treatment technology, specifically a waste gas treatment device for boric acid production. Background Technology

[0002] Boric acid, as an important inorganic chemical raw material, is widely used in glass, ceramics, and pharmaceutical industries. Its production process (such as acidolysis, crystallization, and drying) generates a large amount of waste gas containing particulate matter (boric acid dust, sodium fluoride dust), small amounts of acid mist, and fluorides. Direct emission of this waste gas not only causes air pollution but also erodes surrounding soil and water bodies. Furthermore, dust accumulation easily adheres to the surfaces of production equipment, affecting its lifespan. Long-term exposure to this type of waste gas can also damage the respiratory system and skin / mucous membranes of operators. Therefore, it requires purification treatment using specialized waste gas treatment devices.

[0003] Currently, baghouse dust collectors are commonly used in the industry as pretreatment equipment for boric acid production waste gas, utilizing the filtration effect of the filter bags to remove particulate matter from the waste gas. However, existing baghouse dust collectors have significant shortcomings in practical applications: Firstly, even after filtration by a single filter bag, fine dust particles may still remain in the waste gas, and direct emission can easily lead to substandard purification efficiency, making it difficult to meet increasingly stringent environmental emission standards; secondly, the connection between the baghouse dust collector and the subsequent waste gas conveying pipeline is mostly achieved through welding or flange fixing. When it is necessary to replace or repair the filter components inside the pipeline, the disassembly and assembly process is cumbersome, time-consuming, and labor-intensive. Furthermore, the sealing performance of flange connections is prone to deterioration over time, easily leading to waste gas leakage problems. Therefore, improvements to the existing technology are needed. Utility Model Content

[0004] The purpose of this invention is to provide a waste gas treatment device for boric acid production to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a waste gas treatment device for boric acid production, comprising a bag filter body, an inlet gas pipe installed at the output end of the bag filter body, a fan installed at the end of the inlet gas pipe; a transfer pipe installed at the end of the inlet gas pipe, a connecting pipe installed at the output end of the fan, a filter sealing cover installed between the transfer pipe and the connecting pipe; a filter assembly installed at the center of the filter sealing cover, a dust outlet funnel installed at the bottom end of the bag filter body, a dust collector bag installed inside the bag filter body, a maintenance port installed on the side wall of the dust outlet funnel, and an outlet pipe installed at the input end of the fan.

[0006] In a preferred embodiment of the waste gas treatment device for boric acid production according to this utility model, the end of the transfer pipe is inserted into the left end of the filter sealing cover, the end of the connecting pipe is inserted into the right end of the filter sealing cover, the outer wall of the transfer pipe is provided with external threads, and the inner wall of the filter sealing cover is provided with internal threads, and the external threads and internal threads are matched.

[0007] In a preferred embodiment of the waste gas treatment device for boric acid production according to this utility model, the end of the connecting pipe is fitted with a limiting ring plate inside the filter sealing cover, and the outer diameter of the limiting ring plate is larger than the inner diameter of the filter sealing cover.

[0008] As a preferred embodiment of the waste gas treatment device for boric acid production according to this utility model, the filter assembly includes a support ring and a filter ring installed inside the filter sealing cover. The filter ring is fitted with a filter screen plate. Fixing holes are provided at both ends of the side walls of the support ring and the filter ring, and fasteners are installed in the fixing holes.

[0009] As a preferred embodiment of the waste gas treatment device for boric acid production according to this utility model, the fastener includes a fastening screw and an anti-loosening screw. A fastening nut is screwed onto the outside of the fastening screw. An anti-loosening groove is provided at the bottom end of the fastening screw, and the anti-loosening screw is screwed into the anti-loosening groove. An anti-loosening sleeve is sleeved on the outside of the anti-loosening screw. Three limiting posts are installed on the outer wall of the anti-loosening sleeve. The three limiting posts are distributed in a triangle. The inner wall of each limiting post is provided with a spiral groove that cooperates with the fastening screw. An annular rotating groove is provided on the outer wall of the fastening nut, and the end of the limiting post is located in the annular rotating groove.

[0010] In a preferred embodiment of the waste gas treatment device for boric acid production according to this utility model, a fixing ring is fixedly installed on the upper outer end of the fastening screw, and an annular pressure plate, a spring and an annular rubber sheet are fitted on the circumferential surface of the fastening screw, and an extrusion block is fixedly installed at the lower edge of the annular pressure plate.

[0011] As a preferred embodiment of the waste gas treatment device for boric acid production according to this utility model, the main body of the bag filter is fitted with a support frame, the top of the support frame is equipped with a maintenance platform frame, the side wall of the support frame is equipped with a ladder, and the ladder is provided with a protective frame.

[0012] Compared with the prior art, the beneficial effects of this utility model are: the waste gas treatment device for boric acid production has a reasonable structural design; This device adds a filter sealing cover and built-in filter components after the main body of the bag filter, forming a dual filtration structure of "primary bag filtration + secondary filter". The dust collection bags inside the bag filter first perform preliminary filtration of large dust particles in the exhaust gas. The remaining fine dust enters the filter sealing cover with the exhaust gas and is further intercepted by the filter screen embedded in the filter ring in the filter component, effectively reducing the particulate matter content in the exhaust gas. Compared with single bag filtration, the purification efficiency is significantly improved, which can better meet the environmental emission requirements and avoid the pollution problems caused by the direct emission of fine dust. The adapter pipe and filter sealing cover are connected by external and internal threads. Compared with traditional welding or flange connections, this not only simplifies the disassembly and assembly process (the filter sealing cover can be disassembled and installed without the need for complicated tools), but also improves the sealing performance of the connection through the tightness of the threaded fit, effectively preventing exhaust gas from leaking at the connection between the adapter pipe and the filter sealing cover. At the same time, the limiting ring plate design at the end of the connecting pipe can limit the right end of the filter sealing cover, avoiding excessive tightening during threaded connection that could cause pressure damage to the filter assembly, further ensuring the stability of the device operation. Attached Figure Description

[0013] Figure 1 This is a front-view three-dimensional structural schematic diagram of the present invention; Figure 2 This is a front view of the present utility model; Figure 3 This is a schematic diagram of the adapter pipe, filter sealing cover, and connecting pipe of this utility model; Figure 4 This is a schematic diagram of the fastener of this utility model.

[0014] In the diagram: 1. Main body of baghouse dust collector; 2. Support frame; 3. Ladder; 4. Protective frame; 5. Maintenance platform frame; 6. Dust collection funnel; 7. Maintenance port; 8. Air inlet pipe; 9. Fan; 10. Adaptor pipe; 11. Filter sealing cover; 12. Connecting pipe; 13. Discharge pipe; 14. Internal thread; 15. Filter ring; 16. Bearing ring; 17. Fixing hole; 18. Filter screen; 19. Fastener. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0016] Please see Figure 1-4 This utility model provides a technical solution: In this technical solution, a waste gas treatment device for boric acid production includes a bag filter body 1. The output end of the bag filter body 1 is equipped with an inlet gas pipe 8, and the end of the inlet gas pipe 8 is equipped with a fan 9. The end of the inlet gas pipe 8 is equipped with a transfer pipe 10, and the output end of the fan 9 is equipped with a connecting pipe 12. A filter sealing cover 11 is installed between the transfer pipe 10 and the connecting pipe 12. A filter assembly is installed at the center of the filter sealing cover 11. A dust discharge funnel 6 is installed at the bottom of the bag filter body 1. A dust collection bag is installed inside the bag filter body 1. A maintenance port 7 is installed on the side wall of the dust discharge funnel 6. An outlet pipe 33 is installed at the input end of the fan 9.

[0017] The main body of the bag filter (1) is the core pretreatment unit of the entire waste gas treatment device, and its internal space is used to house key filtration components such as dust collector bags. The main body is typically welded from Q235 carbon steel, a material known for its good strength and economy, ability to withstand certain pressures and resistance to deformation, effectively handling the waste gas treatment conditions of boric acid production. To enhance its corrosion resistance, the exterior of the main body is generally painted or galvanized, with a paint layer thickness of approximately 80-120μm and a galvanized layer thickness of 50-80μm. This protects against the corrosive effects of any small amounts of acidic substances that may be present in the waste gas, extending the equipment's service life. The dimensions of the main unit depend on the actual volume of waste gas to be treated. Common small units may have dimensions of 1.5m in length, 1m in width, and 2m in height; medium-sized units are approximately 3m in length, 2m in width, and 4m in height; and large units can reach 5m in length, 3m in width, and 6m in height. The effective filtration space inside occupies 70%-80% of the total volume to ensure that the waste gas has sufficient residence time for filtration. The main body should be equipped with a reasonable airflow distribution device, such as a baffle plate or perforated plate, to ensure that the incoming exhaust gas passes evenly through the dust collector bags, avoiding excessively high local airflow velocities that could lead to poor filtration. The baffle plate is generally made of 3-5mm thick stainless steel plate, with the tilt angle determined based on actual airflow simulation results, typically between 30° and 45°. The perforated plate has a pore diameter of 10-15mm and an opening rate of 20%-30% to achieve uniform airflow distribution. Simultaneously, an inspection port should be provided at the top of the main body for convenient periodic inspection and replacement of internal components such as the dust collector bags. The inspection port is generally square with sides of 0.6m-0.8m, equipped with a well-sealed cover. The cover uses a double-layer rubber seal, ensuring no gas leakage under negative pressure conditions ranging from -800Pa to -1500Pa. The exhaust pipe 8 is responsible for transporting the exhaust gas, after preliminary filtration by the main body 1 of the bag filter, to the subsequent treatment unit. Seamless steel pipes are mostly used for the pipes because they have good pressure resistance, can adapt to pressure changes during exhaust gas transport, and have smooth inner walls to reduce resistance during transport. To prevent dust and other impurities in the exhaust gas from causing wear on the inner wall of the pipe, the inner wall can be treated with wear-resistant coatings, such as tungsten carbide coating, with a coating thickness of approximately 0.3-0.5 mm, significantly improving the service life of the pipe. The pipe diameter is designed and calculated based on the waste gas flow rate and velocity. Generally, the waste gas velocity in the pipe is controlled at 12-18 m / s to ensure smooth waste gas transport without excessive pressure drop. For example, for a treatment device with a waste gas flow rate of 10,000 m³ / h, the calculated pipe diameter may be 300-400 mm. The pipeline should be equipped with multiple support points, typically spaced 3-5 meters apart, using steel supports to prevent deformation or damage due to its own weight and internal exhaust gas pressure. Simultaneously, pipeline connections should utilize flanges, with sealing gaskets installed between the flanges. The gaskets should be made of high-temperature resistant, corrosion-resistant rubber or graphite composite materials to ensure a good seal at the connection points and prevent exhaust gas leakage. The sealing gasket thickness should be 3-5 mm, and its sealing performance must ensure no leakage under normal operating pressure and withstand a certain temperature range (e.g., 80℃-150℃). Fan 9 provides power to the entire waste gas treatment system, causing the waste gas to flow within the device. Centrifugal fans are typically selected due to their large flow rate and stable pressure, meeting the requirements for waste gas volume and pressure during boric acid production waste gas treatment. The fan impeller is generally made of aluminum alloy or stainless steel. Aluminum alloy offers advantages such as light weight and high strength, while stainless steel provides better corrosion resistance. The appropriate material can be selected based on the waste gas composition and operating conditions. The impeller undergoes dynamic balancing testing, achieving a balancing accuracy of G6.3 to reduce vibration during fan operation and ensure stable equipment operation. The power of the fan is determined based on factors such as the waste gas treatment capacity, pipeline resistance, and system pressure loss. For example, for a system treating 15,000 m³ / h of waste gas with a total pipeline resistance of 2,000 Pa, the fan power may be between 15 and 22 kW. The fan speed is generally between 1450 and 2900 r / min. The fan speed can be adjusted according to actual operating conditions using a variable frequency drive (VFD) for the motor, achieving energy-saving operation. The adapter pipe 10 serves to connect the exhaust gas pipe 8 and the filter sealing cover 11, enabling the redirection and connection of the exhaust gas transport path. The adapter pipe is generally made of the same material as the exhaust gas pipe, i.e., seamless steel pipe, to ensure its strength and corrosion resistance. To facilitate connection with the filter sealing cover 11, one end of the adapter pipe 10 has an external thread 13 machined on its outer wall. The specification of the external thread is determined according to the internal thread size of the filter sealing cover 11, commonly using standard thread specifications such as M50×2 and M60×2, ensuring a tight connection. The length of the transfer pipe 10 is determined according to the actual installation space and connection requirements, generally between 0.3-0.5m. The pipe diameter is consistent with that of the exhaust pipe 8 to ensure the stability of the exhaust gas flow. The connecting pipe 12 is used to transport the exhaust gas, after secondary filtration by the filter sealing cover 11, to subsequent discharge or further treatment stages. Its material, manufacturing process, and related requirements are similar to those of the exhaust gas pipe 8; it also uses seamless steel pipe, and the inner wall can be treated for wear resistance. The pipe diameter is determined according to the exhaust gas flow rate and velocity. The connection between the connecting pipe 12 and the output end of the fan 9 is mostly through flange connection to ensure a firm connection and good sealing, preventing exhaust gas leakage. The principle for calculating the pipe diameter is the same as that for the exhaust pipe 8. If the flow rate of the exhaust gas is slightly reduced after secondary filtration, assuming the flow rate becomes 9000 m³ / h and the flow velocity is still controlled at 12-18 m / s, then the pipe diameter may be between 250-350 mm. The length of the connecting pipe 12 is determined according to the actual layout, and is generally between 0.5-1 m. The filter sealing cover 11 is a key component for achieving secondary filtration of exhaust gas. The filter assembly installed inside it further intercepts fine dust remaining after the initial filtration by the main body of the bag filter 1. The filter sealing cover is made of stainless steel, such as 304 stainless steel, which has excellent corrosion resistance and can effectively resist the erosion of acidic substances that may be present in the exhaust gas. The design of the sealing cover should ensure good sealing performance to prevent the leakage of unfiltered exhaust gas.

[0018] The dimensions of the filter sealing cover 11 are determined based on the size of the internal filter components and the installation space, and are generally a cylindrical structure with a diameter of 0.4-0.6m and a length of 0.6-0.8m. Its internal space should be large enough to accommodate the filter components and ensure sufficient flow space for exhaust gas to achieve adequate filtration. The filter assembly is the core component of the filter sealing cover 11, consisting of a support ring 16 and a filter ring 15. The support ring 16 supports the filter ring 15 and the filter screen 18, and is made of stainless steel plate with a thickness of 5-8mm to ensure sufficient strength. The filter screen 18 embedded inside the filter ring 15 is the key element for dust filtration. The filter screen can be made of stainless steel woven mesh or sintered mesh. Stainless steel woven mesh has the characteristics of high filtration accuracy and large flow rate, while sintered mesh has better strength and stability. The diameter of the filter ring 15 is generally 30-50mm smaller than the inner diameter of the filter sealing cover 11 to ensure sufficient airflow channel after installation. The filtration accuracy of the filter screen 18 is determined according to the size of the dust particles in the exhaust gas. For fine dust in boric acid production exhaust gas, the filtration accuracy can reach 5-10μm, which can effectively intercept the tiny particles that the bag filter cannot filter out. The dust discharge hopper 6 is used to collect the dust filtered by the main body 1 of the bag filter. Its shape is an inverted cone, which facilitates the natural sliding of dust under gravity. The dust discharge hopper is made of 3-5mm thick Q235 carbon steel, and the surface can be treated with anti-corrosion coatings, such as painting, with a paint layer thickness of 80-120μm. To ensure smooth dust flow, the cone angle of the dust discharge hopper is generally between 60° and 70°; for boric acid dust, a cone angle of 65° is more suitable. The upper opening size of the dust discharge hopper matches the bottom size of the main body 1 of the bag filter, while the lower opening size is determined based on the interface of the subsequent ash discharge equipment, generally with a lower opening diameter between 0.2 and 0.3 meters. The height of the dust discharge hopper is determined based on the overall equipment layout and the amount of dust accumulation, generally between 0.8 and 1.2 meters. The filter bag is the core filtration element of the baghouse dust collector (body 1), performing preliminary filtration of large dust particles in the exhaust gas. The filter bag is woven from special fibers such as polyester, Nomex, or PPS. These materials have excellent temperature and corrosion resistance, and can adapt to the working conditions of boric acid production exhaust gas. For example, polyester fiber is suitable for exhaust gas environments with temperatures below 120℃, Nomex can withstand temperatures around 190℃, and PPS can operate stably in high-temperature environments of 200℃-240℃. The surface of the filter bag is generally treated, such as singeing or calendering, to enhance its filtration performance and dust removal effect. The diameter of dust collector bags is commonly 120-160mm, and the length is generally between 2-6m. The specific dimensions are determined based on the internal space of the baghouse dust collector body 1 and the filtration requirements. For example, for small baghouse dust collectors, the bag diameter may be 120mm and the length 2m; for medium-sized dust collectors, the bag diameter is 140mm and the length is 4m; and for large dust collectors, the bag diameter is 160mm and the length is 6m. The filtration area of ​​the bag can be calculated using a formula. Generally, the amount of waste gas that can be treated per square meter of filtration area is 1-5 m³ / min, and the specific value is adjusted according to factors such as waste gas concentration and dust properties. Maintenance port 7 provides a convenient passage for cleaning accumulated dust inside the dust outlet funnel 6 and for inspecting related components. The maintenance port is generally square in shape and made of the same material as the dust outlet funnel, namely Q235 carbon steel. The cover of the maintenance port is hinged to the side wall of the dust outlet funnel for easy opening and closing. A rubber sealing strip is used to seal the cover and the dust outlet funnel to ensure no dust leakage during equipment operation. The maintenance port is typically a square with sides of 0.3-0.4m, which satisfies the operator's hand space requirements without significantly affecting the structural strength of the dust collection funnel. The discharge pipe 33 is used to discharge the purified exhaust gas from the entire exhaust gas treatment device into the atmosphere. The discharge pipe is generally made of the same seamless steel pipe as the connecting pipe to ensure strength and corrosion resistance. The height of the discharge pipe is determined according to local environmental protection requirements, and it generally needs to be a certain distance above surrounding buildings to ensure effective dispersion of exhaust gas and reduce its impact on the surrounding environment. The diameter of the discharge pipe is determined based on the exhaust gas flow rate and the emission velocity specified in the emission standards. For example, if the exhaust gas flow rate is 8000 m³ / h and the emission standard stipulates that the emission velocity should not exceed 25 m / s, the calculated pipe diameter may be 200-300 mm. The height of the discharge pipe may be required to be 15-20 m in general industrial areas, and may be higher in environmentally sensitive areas. In some technical solutions, the end of the adapter pipe 10 is inserted into the left end of the filter sealing cover 11, and the end of the connecting pipe 12 is inserted into the right end of the filter sealing cover 11. The outer wall of the adapter pipe 10 is provided with an external thread 13, and the inner wall of the filter sealing cover 11 is provided with an internal thread 14. The external thread 13 and the internal thread 14 are matched.

[0019] The threaded connection between the adapter pipe 10 and the filter sealing cover 11 is a "sealing thread" structure, requiring double protection against leakage through thread gap sealing and a sealing ring. The insertion end of the adapter pipe is ≥80mm long, with an external thread 13 (7h precision) machined on the outer wall, and the thread crest must be rounded (R0.5mm) to prevent scratching the sealing ring; the inner wall of the left end of the filter sealing cover is machined with an internal thread 14 (7H precision), and a sealing groove (8mm width, 4mm depth) is opened at the bottom of the thread, with an internal O-ring (fluororubber material, 4mm cross-sectional diameter) installed. The outer diameter of the adapter connector is 0.5~1mm smaller than the inner diameter of the left end of the filter sealing cover (e.g., the inner diameter of the cover is Φ350mm, and the outer diameter of the adapter connector is Φ349.5mm) to ensure smooth insertion; the external thread is 13mm with a pitch of 3mm, a thread height of 1.732mm, and an effective thread length of 100mm; the radial clearance after thread mating is ≤0.2mm, and the axial compression (sealing ring) is 1~1.5mm to ensure sealing effect.

[0020] In some technical solutions, the end of the connecting pipe 12 is fitted with a limiting ring plate inside the filter sealing cover 11, and the outer diameter of the limiting ring plate is larger than the inner diameter of the filter sealing cover 11.

[0021] The limiting ring plate is a "ring-shaped stop" used to limit the insertion depth of the connecting pipe 12 and enhance the connection stability between the connecting pipe and the filter sealing cover. The ring plate is made of 304 stainless steel (10mm thick) and is welded to the connecting pipe (argon arc welding, weld height 8mm, post-weld flaw detection); the outer diameter of the ring plate is 5~10mm larger than the inner diameter of the filter sealing cover (e.g., if the inner diameter of the cover is Φ350mm, the outer diameter of the ring plate is Φ360mm), ensuring that it cannot be inserted from the opening at the right end of the cover; The inner diameter of the limiting ring plate is the same as the outer diameter of the connecting pipe (e.g., the outer diameter of the connecting pipe is Φ300mm, and the inner diameter of the ring plate is Φ300mm), and the width of the ring plate is 20mm; the welding position is 50mm away from the end of the connecting pipe to ensure that after the connecting pipe is inserted, the gap between the ring plate and the right end face of the cover is ≤2mm; an asbestos gasket (2mm thick, temperature resistance ≤200℃) needs to be placed between the ring plate and the end face of the cover to reduce vibration and friction.

[0022] In some technical solutions, the filter assembly includes a support ring 16 and a filter ring 15 installed inside the filter sealing cover. A filter screen plate 18 is embedded inside the filter ring 15. Fixing holes 17 are opened at both ends of the side walls of the support ring 16 and the filter ring 15, and fasteners 19 are installed in the fixing holes 17.

[0023] The support ring 16 and the filter ring 15 are rigidly connected by fasteners 19 to ensure the overall stability of the filter assembly. The fixing hole 17 is a stepped hole structure (hole diameter Φ14mm, countersunk hole diameter Φ20mm, depth 5mm) to accommodate the head of the fastener 19 and prevent it from protruding and affecting airflow; the filter screen plate 18 is embedded in the "U"-shaped groove of the filter ring 15, and the groove is coated with high-temperature resistant sealant (temperature resistance ≤150℃) to prevent dust from leaking from the gap between the plate and the groove; There are 4 fixing holes 17, distributed at 90°, with the center of the hole 20mm from the edge of the bearing ring / filter ring; the countersunk hole depth is 5mm, matching the head height of the fastener 19 (e.g., bolt head height 4.5mm); the fit clearance between the filter screen plate 18 and the filter ring groove is ≤0.3mm, the sealant coating thickness is 1~2mm, and the adhesive layer width is 5mm.

[0024] In some technical solutions, the fastener 19 includes a fastening screw 20 and an anti-loosening screw 24. A fastening nut 21 is screwed onto the outside of the fastening screw 20. An anti-loosening groove 22 is provided at the bottom end of the fastening screw 20. The anti-loosening screw 24 is screwed into the anti-loosening groove 22. An anti-loosening sleeve 23 is sleeved on the outside of the anti-loosening sleeve 24. Three limiting posts 25 are installed on the outer wall of the anti-loosening sleeve 23. The three limiting posts 25 are distributed in a triangle. The inner wall of each limiting post 25 is provided with a spiral groove 26 that cooperates with the fastening screw 20. An annular groove 27 is provided on the outer wall of the fastening nut 21. The end of the limiting post 25 is located in the annular groove 27.

[0025] Fastener 19 is an "anti-loosening structure" that restricts the loosening of the fastening nut 21 through the cooperation of the limiting post 25 and the annular groove 27. The fastening screw 20 is made of 304 stainless steel (diameter Φ12mm, length 50mm) with an external thread specification of M12×1.75 (precision 6g); the anti-loosening screw groove 22 is a blind hole (diameter Φ8mm, depth 15mm) with an internal thread specification of M8×1.25 (precision 6H); the anti-loosening sleeve 23 is made of 304 stainless steel (inner diameter Φ8mm, outer diameter Φ16mm, length 20mm), and its inner wall is clearance-fitted with the anti-loosening screw 24 (clearance 0.1~0.2mm). The limiting post 25 is made of 304 stainless steel (diameter Φ6mm, length 25mm), and three of them are distributed at 120°. The inner wall spiral groove 26 has the same specifications as the fastening screw 20 (M12×1.75). The annular groove 27 is opened on the outer wall of the fastening nut 21 (width 6mm, depth 3mm). The end of the limiting post 25 is inserted into the groove, and the fit clearance is ≤0.2mm. The anti-loosening screw 24 is made of 304 stainless steel (diameter Φ8mm, length 30mm), with an external thread specification of M8×1.25. After tightening, the gap between it and the end face of the anti-loosening cylinder 23 is ≤1mm.

[0026] In some technical solutions, a retaining ring 28 is fixedly installed on the upper outer end of the fastening screw 20, and an annular pressure plate 30, a spring 32 and an annular rubber sheet 31 are fitted on the circumferential surface of the fastening screw 20. An extrusion block 29 is fixedly installed at the lower edge of the annular pressure plate 30.

[0027] This structure achieves a "self-tightening seal" through the elastic force of spring 32, compensating for fastener loosening caused by vibration. The fixing ring 28 is an annular structure (made of 304 stainless steel, 5mm thick, inner diameter Φ12mm), welded to the fastening screw 20 (weld height 3mm), used to limit the axial displacement of the annular pressure plate 30; the annular pressure plate 30 is made of 304 stainless steel (diameter Φ20mm, thickness 3mm), and the lower end extrusion block 29 is a "wedge-shaped" structure (3 blocks, distributed at 120°, height 5mm), used to extrude the annular rubber sheet 31; Spring 32 is a cylindrical helical compression spring (material 60Si2Mn, wire diameter 2mm, outer diameter Φ16mm, free length 25mm, stiffness 5N / mm), with a working compression of 5~8mm, providing an elastic force of 25~40N; the annular rubber sheet 31 is made of fluororubber (diameter Φ20mm, inner diameter Φ12mm, thickness 8mm), with a Shore hardness of 60±5A; the wedge angle of the extrusion block 29 is 30°, and the rubber sheet is compressed by 2~3mm after extrusion, achieving a seal.

[0028] In some technical solutions, the main body 1 of the bag filter is fitted with a support frame 2, the top of the support frame 2 is equipped with a maintenance platform frame 5, the side wall of the support frame 2 is equipped with a ladder 3, and the outside of the ladder 3 is equipped with a protective frame 4.

[0029] Support frame 2 is the load-bearing structure of the main body 1, and must withstand the equipment's own weight (including dust) and wind load. It is made of Q235B carbon steel (section steel specifications H300×150×6.5×9), using welded connections with a weld height ≥8mm. After welding, it undergoes overall rust removal (Sa2.5 grade) and is coated with anti-rust paint (dry film thickness 80μm) + topcoat (dry film thickness 60μm). Maintenance platform frame 5 provides standing space for operators during maintenance. The platform is made of patterned steel plate (thickness 5mm, pattern height 2mm), with an anti-slip performance ≥0.5 (coefficient of friction).

[0030] The support frame 2 has the same height as the main body 1 (e.g., if the main body is 6m high, the support frame is 6m high), the column spacing is 2m, and the cross brace spacing is 1.5m; the maintenance platform frame 5 has dimensions (length × width) of 2m × 1.5m, a guardrail height of 1.2m, and a guardrail crossbar spacing of 300mm; the ladder 3 has anti-slip steel plate steps (thickness 4mm, size 200mm × 300mm), a step spacing of 300mm, and a ladder width of 600mm; the protective frame 4 has a grid structure (material ∠30×3 angle steel, wire diameter 4mm, grid size 100×100mm), and the same height as the ladder.

[0031] Working process and principle: I. Work Process 1. System startup and exhaust gas introduction phase Before starting the device, the status of each component must be checked: confirm that the dust collector bags are installed in place inside the main body 1 of the bag filter, the filter components inside the filter sealing cover 11 are firmly fixed, the sealing gaskets of each pipe flange are undamaged, and the vibration damping pads of the fan 9 are not aged. Start the fan 9 (motor drives the impeller to rotate), and a stable negative pressure (≤-1800Pa) is formed in the system. The dust-containing waste gas (containing boric acid dust, sodium fluoride dust and trace amounts of acid mist) generated during the boric acid production process first enters the air inlet of the main body 1 of the bag filter under the action of negative pressure, and the waste gas purification process begins. 2. Primary dust removal stage (bag filter) After the exhaust gas enters the main body 1 of the bag filter, it is guided by the internal guide cone (cone angle 60°) and flows evenly to the dust collector bag area. The dust collector bags are made of PPS needle-punched felt membrane material, whose fiber pores (pore size ≤10μm after membrane) can capture large dust particles (such as boric acid crystal dust) with a particle size ≥10μm in the exhaust gas through interception, inertial collision, and diffusion. During the purification process, the pulse cleaning device is activated according to a preset cycle (30~60s): the electromagnetic pulse valve (working pressure 0.4~0.6MPa) sprays compressed air into the bag, with a single spray time of 0.1~0.2s, causing the bag to expand and then contract instantly, shaking off the dust adhering to the surface into the bottom dust outlet funnel 6. Dust gradually accumulates in the dust discharge hopper 6. When the level gauge (RF admittance type) detects that the dust reaches 80% of the hopper volume, the dust discharge alarm is triggered, and the star-shaped unloader (discharge rate 0.5~1m³ / h) is started to discharge the dust evenly to the collection device. If dust bridging occurs on the inner wall of the hopper, the side wall maintenance port 7 can be opened (the cover can be opened through the hinge, cleaned, closed and tightened with M12 bolts, torque 25N・m), or the vibrator on the outer wall of the hopper can be started to assist in the dust discharge. 3. Secondary filtration (precision filtration) stage The exhaust gas after primary dust removal (still containing 5~10μm fine dust) is transported to the transfer pipe 10 through the exhaust pipe 8 (flow velocity 14~16m / s, slope 3‰~5‰ to prevent condensate accumulation). The transfer pipe 10 is connected to the filter sealing cover 11 by the external thread 13 and the internal thread 14 (thread clearance ≤0.2mm, double seal with O-ring at the root), guiding the exhaust gas into the filter sealing cover 11. After the exhaust gas enters the filter sealing cover 11, it is guided by the positioning block on the inner wall and flows to the central filter assembly. It first contacts the filter structure composed of the support ring 16 and the filter ring 15. The multi-layer sintered stainless steel mesh (100 mesh in the upper layer, 200 mesh in the middle layer, and 300 mesh in the lower layer) embedded in the filter ring 15 intercepts fine dust particles with a diameter of 5~10μm through deep filtration. During the filtration process, the pipeline pressure transmitter (measurement range -2000Pa~0Pa) monitors the pressure in the exhaust gas pipeline 8 in real time. If the pressure difference exceeds 500Pa, it indicates that the filter assembly or dust collector bag is blocked, and the machine needs to be stopped for maintenance (close the manual butterfly valve on the connecting pipe 12, remove the quick-opening maintenance door of the filter sealing cover 11, and replace the filter screen 18 or dust collector bag). 4. Clean Gas Emission and System Maintenance Phase The clean exhaust gas (particulate matter concentration ≤5mg / m³) after secondary filtration is transported to the output end of fan 9 through connecting pipe 12 (flow velocity 15~18m / s), and then discharged into the atmosphere through discharge pipe 33 (height 15~20m, exceeding 2m above surrounding buildings). During the discharge process, the online monitoring interface in the middle of discharge pipe 33 can be connected to a particulate matter concentration monitor (accuracy ±5%) to monitor emission indicators in real time; the top rain cap (cone angle 60°) prevents rainwater backflow, and the bottom support is fixed by M24 anchor bolts (pre-embedded depth ≥500mm) to ensure pipeline stability. After the system has been running for 1-2 months, regular maintenance is required: Climb the maintenance platform frame 5 (guardrail height 1.2m, lower anti-fall net load capacity ≥500kg) via ladder 3 (step spacing 300mm, external protective frame 4 grid size 100×100mm) to check the working condition of the pulse valve at the top of the bag filter body 1; open the quick-opening maintenance door of the filter sealing cover 11, remove the fasteners 19, take out the filter components, and clean or replace the filter screen 18; at the same time, clean the residual dust in the dust discharge funnel 6, and check whether the sealing ring (fluororubber material) of the maintenance port 7 is aging to ensure the sealing performance in subsequent operation. II. Core Working Principle 1. Filtration principle of dust collector bags The dust collector bags adopt a "membrane-coated needle-punched felt" structure, with the core principle of surface filtration + depth filtration: The PTFE coating on the surface (0.1mm thick) has a pore size of ≤10μm, which can directly intercept large dust particles and form a "dust primary layer". Subsequent dust passes through the primary layer for filtration, improving the filtration accuracy. The bottom needle-punched felt fibers are distributed in three dimensions, and further capture fine dust through inertial collision (large particles cannot follow the airflow around the fibers due to inertia and are captured after collision) and Brownian diffusion (small particles are randomly moved by the impact of gas molecules and are captured after contact with the fibers). During pulse cleaning, compressed air is sprayed to cause the filter bag to expand in the opposite direction, breaking the adhesion between the initial dust layer and the fibers. The dust falls into the dust outlet funnel under the action of gravity, thus regenerating the filter bag. 2. Precision filtration principle of the filter assembly The filter assembly adopts a "multi-layer sintered stainless steel mesh" structure, and its core principle is gradient filtration + sealing interception. The three-layer filter is distributed with a precision gradient of "100 mesh → 200 mesh → 300 mesh". The upper layer (100 mesh) first intercepts larger residual dust and reduces the load on the lower filter; the middle layer (200 mesh) further filters medium-sized dust particles; and the lower layer (300 mesh) finally captures fine dust particles with a diameter of 5μm, achieving "step-by-step purification". The filter screen plate 18 is embedded in the "U" shaped groove of the filter ring 15. The groove is coated with high-temperature resistant sealant (temperature resistance ≤150℃), and is fitted with silicone sealing gaskets (thickness 5mm) at both ends to ensure that the exhaust gas has no bypass leakage and must pass through the filter screen to improve the filtration efficiency (up to 99.9% or more). The radial guide grooves (8 grooves, 5mm wide and 3mm deep) on the inner wall of the filter ring 15 guide the exhaust gas to be evenly distributed on the filter screen surface, avoiding excessive local flow velocity (≤1.5m / s) which may cause filter screen damage or uneven filtration. 3. The anti-loosening and sealing principle of fasteners Fastener 19 adopts a composite structure of "mechanical anti-loosening + elastic sealing", and its core principle is multi-directional limiting + self-tightening compensation. The three limiting posts 25 on the outer wall of the anti-detachment cylinder 23 (distributed at 120°) are inserted into the annular groove 27 of the fastening nut 21, and engage with the thread of the fastening screw 20 through the inner spiral groove 26, thereby restricting the rotation of the nut radially and circumferentially and preventing loosening caused by vibration. The spring 32 (stiffness 5N / mm) outside the fastening screw 20 is compressed by 5~8mm during installation, generating a continuous elastic force of 25~40N. This force acts on the annular rubber sheet 31 through the wedge-shaped extrusion block 29 (angle 30°) of the annular pressure plate 30, compressing the rubber sheet by 2~3mm and filling the connection gap between the bearing ring 16 and the filter ring 15 to achieve a seal. At the same time, the spring force can compensate for bolt deformation caused by temperature changes or vibration, maintaining long-term sealing pressure. 4. System negative pressure and airflow stabilization principle Fan 9 (centrifugal type, 2500Pa total pressure) provides the core power for the system. Its working principle is that the impeller rotation generates centrifugal force. When the impeller rotates at high speed (1450 r / min), the gas between the blades is thrown out by centrifugal force, forming a negative pressure at the center of the impeller and drawing in exhaust gas; the thrown-out gas enters the connecting pipe 12 after being guided by the casing, forming a stable airflow; The pipeline design follows the principle of "low resistance + anti-deposition": the pipe diameter is calculated based on a flow velocity of 14~18m / s (e.g., Φ300mm pipe diameter corresponds to 18000m³ / h of exhaust gas), and large-radius elbows (R≥3D) are used at bends to reduce local resistance; the pipeline slope is 3‰~5‰ downward along the airflow direction, and a drain outlet (DN50) is provided every 10m to avoid condensate and dust from mixing and depositing, ensuring stable airflow delivery. 5. Corrosion Prevention and Structural Stability Principles To address the fluorides and acid mist in boric acid waste gas, the device achieves corrosion protection through material selection and coating protection: Components in contact with clean exhaust gas (such as connecting pipe 12 and filter sealing cover 11) are made of 304 stainless steel (containing ≥8% nickel), which can withstand immersion in 10% sulfuric acid for 48 hours without corrosion; pipes in contact with dusty exhaust gas (such as exhaust pipe 8) are made of 20# seamless steel pipe lined with PTFE coating (thickness 0.2~0.3mm), which is resistant to fluorine corrosion and has a smooth inner wall (Ra≤6.3μm). The carbon steel components such as support frame 2 and dust hopper 6 are treated with "Sa2.5 grade rust removal + rust-preventive paint (80μm) + topcoat (60μm)" to prevent atmospheric corrosion; Structural stability is achieved through rigid support and vibration damping design: support frame 2 is made of H300 steel, with column spacing of 2m and cross brace spacing of 1.5m. The bottom embedded plate is fixed with M24 anchor bolts; the fan base is equipped with 50mm thick rubber vibration damping pads (vibration damping efficiency ≥80%) to reduce vibration transmission and avoid structural loosening caused by long-term operation.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0033] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in this invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A waste gas treatment device for boric acid production, comprising a bag filter body (1), characterized in that, The output end of the main body (1) of the bag filter is equipped with an air inlet pipe (8), and the end of the air inlet pipe (8) is equipped with a fan (9). The end of the exhaust pipe (8) is equipped with a transfer pipe (10), the output end of the fan (9) is equipped with a connecting pipe (12), and a filter sealing cover (11) is installed between the transfer pipe (10) and the connecting pipe (12). The filter sealing cover (11) is equipped with a filter assembly at its center, the bottom of the bag filter body (1) is equipped with a dust discharge funnel (6), the inside of the bag filter body (1) is equipped with a dust collection bag, the side wall of the dust discharge funnel (6) is equipped with a maintenance port (7), and the input end of the fan (9) is equipped with a discharge pipe (33).

2. The waste gas treatment device for boric acid production according to claim 1, characterized in that, The end of the adapter pipe (10) is inserted into the left end of the filter sealing cover (11), and the end of the connecting pipe (12) is inserted into the right end of the filter sealing cover (11). The outer wall of the adapter pipe (10) is provided with an external thread (13), and the inner wall of the filter sealing cover (11) is provided with an internal thread (14). The external thread (13) and the internal thread (14) are matched.

3. The waste gas treatment device for boric acid production according to claim 2, characterized in that, The end of the connecting pipe (12) is fitted with a limiting ring plate inside the filter sealing cover (11), and the outer diameter of the limiting ring plate is larger than the inner diameter of the filter sealing cover (11).

4. The waste gas treatment device for boric acid production according to claim 1, characterized in that, The filter assembly includes a support ring (16) and a filter ring (15) installed inside the filter sealing cover. The filter ring (15) is fitted with a filter screen plate (18). Fixing holes (17) are provided at both ends of the side walls of the support ring (16) and the filter ring (15), and fasteners (19) are installed in the fixing holes (17).

5. The waste gas treatment device for boric acid production according to claim 4, characterized in that, The fastener (19) includes a fastening screw (20) and an anti-loosening screw (24). A fastening nut (21) is screwed onto the outside of the fastening screw (20). An anti-loosening groove (22) is provided at the bottom end of the fastening screw (20). The anti-loosening screw (24) is screwed into the anti-loosening groove (22). An anti-loosening sleeve (23) is sleeved on the outside of the anti-loosening screw (24). Three limiting posts (25) are installed on the outer wall of the anti-loosening sleeve (23). The three limiting posts (25) are arranged in a triangle. The inner wall of each limiting post (25) is provided with a spiral groove (26) that cooperates with the fastening screw (20). An annular rotating groove (27) is provided on the outer wall of the fastening nut (21). The end of the limiting post (25) is located in the annular rotating groove (27).

6. The waste gas treatment device for boric acid production according to claim 5, characterized in that, A retaining ring (28) is fixedly installed on the upper outer end of the fastening screw (20). An annular pressure plate (30), a spring (32) and an annular rubber sheet (31) are fitted on the circumferential surface of the fastening screw (20). An extrusion block (29) is fixedly installed at the lower edge of the annular pressure plate (30).

7. The waste gas treatment device for boric acid production according to claim 1, characterized in that, The main body (1) of the bag filter is fitted with a support frame (2), the top of the support frame (2) is fitted with a maintenance platform frame (5), the side wall of the support frame (2) is fitted with a ladder (3), and the outside of the ladder (3) is fitted with a protective frame (4).

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