Cement kiln bypass co-dechlorination and layered filter dust collector and dechlorination dust removal method

Abstract

This invention discloses a bypass-coordinated dechlorination and stratified filtration dust collector for cement kilns, and a dechlorination and dust removal method, suitable for high-temperature flue gas treatment within a temperature window of 200~300℃. The dust collector includes a filter housing, within which a dechlorination chamber, a dust removal chamber, and a clean gas chamber are sequentially formed along the flue gas flow direction. The dechlorination chamber is equipped with an alkaline dry powder injection device and an S-shaped flow guiding structure composed of baffles and inclined guide plates. By extending the flue gas path and counter-current injection, the alkaline agent reacts fully with trace amounts of HCl gas to generate solid chloride salts. The dust removal chamber is equipped with an array of double-layer filtration devices, consisting of an inner filter bag and an outer filter screen forming a sandwich cavity. The inner wall of the inner filter bag is equipped with an adaptive beam shaping component, which can drive the filter bag to partially expand outward and abut against the outer filter screen during shock wave backflushing, dividing the sandwich cavity into several flow-limiting channels. After backflushing, the cavity is reset to an integrated space. This invention achieves integrated synergistic operation of fine dechlorination and efficient dust removal, with a simplified structure and stable and reliable operation.

Description

Technical Field

[0001] This invention relates to dechlorination and dust removal technology for cement clinker calcination, and in particular to a cement kiln bypass co-dechlorination and stratified filtration dust collector and dechlorination and dust removal method. Background Technology

[0002] During the calcination of cement clinker, chlorine in the raw materials and fuels volatilizes under high-temperature calcination conditions, forming chloride gas that circulates and accumulates within the kiln system. To mitigate the adverse effects of chlorine circulation on clinker quality and kiln equipment, a bypass venting system is typically installed between the preheater and the rotary kiln to extract some of the chlorine-containing high-temperature flue gas outside the kiln for treatment. The chlorine-containing components in the bypass flue gas exist primarily in two forms: crystalline chloride salt solid particles adhering to the surface of fine dust, and trace amounts of HCl gas remaining in gaseous form. The former can be intercepted through dust removal processes, while the latter, due to its gaseous nature, is difficult to capture directly by conventional filter bags. Without targeted treatment, it will be emitted into the atmosphere with the purified flue gas, resulting in incomplete dechlorination and secondary problems such as pipeline corrosion and environmental pollution.

[0003] Existing dechlorination processes mostly employ wet scrubbing or independent dry absorption devices to treat HCl gas. These are independently set up from the dust removal system, resulting in dispersed process flows, large equipment footprints, and low system integration. While integrated solutions that directly introduce alkaline dry powder into the dust removal process have been explored, the resulting solid chloride particles, if not intercepted by layers and directly enter the inner filter bags, are highly prone to clogging the filter bag pores due to their small particle size and strong adhesion, affecting filtration accuracy and filter bag lifespan. Furthermore, existing dust collectors also have shortcomings in cleaning efficiency: the high-temperature filter bags use high-temperature resistant materials such as glass fiber filter media and metal mesh membranes (see announcement number CN213313852U), resulting in high bag rigidity and small deformation. Cleaning relies heavily on the direct scouring of the backflushing airflow. Meanwhile, bypass dust has strong adhesion; during backflushing, fine dust easily moves disorderly within the cavity between the outer wall of the filter bag and the supporting structure, forming eddies, causing secondary adhesion and caking, severely restricting cleaning efficiency.

[0004] The above problems indicate that the existing technology lacks an integrated technical solution that can organically combine the precise removal of gaseous HCl, the stratified interception of solid chloride salts, and the efficient cleaning of high-temperature filter bags, and urgently needs improvement. Summary of the Invention

[0005] The technical problem that the invention aims to solve is that in the existing technology, the dechlorination and dust removal processes are independent of each other, and the equipment integration is low; the traditional single-layer filter bag structure lacks dynamic control of the interlayer space, and the dust moves randomly in the cavity during shock wave cleaning.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: Option 1 (device): A cement kiln bypass co-processing dechlorination and stratified filtration dust collector, comprising a filter housing. Within the filter housing, along the flue gas flow direction, a dechlorination chamber, a dust removal chamber, and a clean air chamber are sequentially formed, with the three chambers functionally zoned and operating collaboratively. The dechlorination chamber is equipped with an alkaline dry powder injection device to inject alkaline dry powder into the flue gas, causing it to neutralize with trace amounts of HCl gas within a temperature range of 200–300°C, generating solid chloride salt particles, thus achieving fine dechlorination. The dust removal chamber contains an array of multiple double-layer filtration devices. Each double-layer filtration device consists of an inner filter bag, an outer filter screen, and an adaptive beam shaping component disposed on the inner wall of the inner filter bag, forming a cavity between the inner filter bag and the outer filter screen. The clean air chamber connects to a negative pressure adsorption system and a shock wave cleaning system, with airflow driven through a connecting hole above the double-layer filtration devices. The adaptive beam shaping component is configured to: during shock wave backflushing, drive the inner filter bag to expand locally and abut against the outer filter screen, dynamically dividing the interlayer cavity into several flow-limiting channels to constrain the dust to fall in a specific direction; after the backflushing ends, automatically reset so that the interlayer cavity returns to an integrated connected space, which is conducive to the smooth flow of flue gas during the negative pressure adsorption stage.

[0007] Based on the above scheme, the adaptive beam shaping component includes multiple annular elastic skeletons spaced apart along the axial direction of the inner filter bag. Each annular elastic skeleton is composed of multiple arc-segment skeletons spliced ​​circumferentially. The arc-segment skeletons themselves are elastic, and their elastic force is less than the airflow force generated during shock wave backflushing. This allows the ends of the arc-segment skeletons to automatically expand outward and abut against the outer filter screen during backflushing, and elastically reset after backflushing stops. The positions of the arc-segment skeletons of the multiple annular elastic skeletons correspond one-to-one, and the segmented seams are aligned longitudinally to form a longitudinally straight flow-blocking structure and a flow-limiting channel without inflection points, ensuring smooth dust fall.

[0008] To ensure the stable and reliable return of the arc-shaped frame, a stabilizing reset structure is installed between the adjacent ends of adjacent arc-shaped frames to provide additional passive reset force. The sum of this force and the elastic force of the arc-shaped frame itself is still less than the airflow force generated by the shock wave backflushing, ensuring reliable outward expansion during backflushing. The stabilizing reset structure can be implemented using magnetic attraction, where an adsorption magnet and a magnetic adsorption layer formed at the end of the arc-shaped frame achieve passive reset through magnetic attraction; alternatively, a non-equivalent elastic spring can be used, utilizing its non-linear elastic deformation to continuously generate low-frequency, micro-amplitude radial vibration during the reset process. Combined with the axial vibration generated by its own weight, this effectively shakes off the fine dust retained on the filter bag at the end of the arc-shaped frame, requiring no additional energy consumption.

[0009] To further enhance the support and shaping performance of the inner filter bag, multiple axially spaced support frames are also provided on the inner wall of the inner filter bag. These frames are interrupted at the points where they pass through the annular elastic frames, thus both constraining and shaping the overall shape of the filter bag and assisting in constraining the stress position of the annular elastic frames. The annular elastic frames are installed within the mounting cavity of the inner filter bag, which is formed by connecting the two ends of flexible splicing pieces to the inner filter bag. The flexible splicing pieces are interrupted at the points where adjacent arc-shaped frames meet, ensuring that the ends can freely expand radially outward and return to their original position. The inner wall of the outer filter screen has an axial limiting fitting at each annular elastic frame. When the ends of the arc-shaped frames expand outward, they are embedded within this fitting, achieving axial limiting and ensuring the stability and reliability of the flow-limiting channel.

[0010] The outer filter is designed with pores smaller than solid chloride particles, trapping coarse dust and solid chloride on the outer layer to prevent clogging of the inner filter bag and achieving fine filtration in layers. The bottom of the outer filter also features a linked dust collection opening and closing structure. During the negative pressure adsorption stage, this structure remains closed, sealing the bottom opening of the outer filter and preventing secondary pollution from settled dust in the bottom hopper. During the shockwave backflushing stage, it automatically opens based on the reverse airflow, providing a directional falling channel for the detached dust, allowing it to smoothly flow into the bottom hopper. The linkage-type dust collection opening and closing structure consists of a valve plate, a return spring, a movable pressure-bearing linkage component, and a perforated dust-removing limiting plate. The movable pressure-bearing linkage component, located at the upper end of the central shaft, receives the airflow impact from the bottom of the inner filter bag, causing the central shaft to move downwards, compressing the return spring, and pushing the valve plate away from the bottom opening to achieve automatic opening. After the backflow airflow disappears, the return spring rebounds, driving the valve plate to reset and close. The perforated dust-removing limiting plate constrains and guides the return spring and the central shaft; its perforated gaps also serve as a dust falling channel, achieving the dual functions of limiting guidance and dust removal. The entire structure relies entirely on pneumatic linkage for passive opening and closing, without any additional driving components.

[0011] Regarding the structural optimization of the dechlorination chamber, a baffle is installed inside the dust removal chamber, separating the inlet and outlet on opposite sides. A flow guide gap is left between one end of the baffle and the chamber wall, forming an isosceles triangle structure with the inlet and outlet. This forces the flue gas to flow through a circuitous path, extending the contact reaction time with the alkaline dry powder. An S-shaped flow guide structure is also installed between the chamber wall and the baffle near the inlet. This structure consists of multiple longitudinally staggered and oppositely arranged oblique flow guide plates forming an S-shaped flue gas channel, further extending the reaction path and promoting flue gas rotation by changing the flow direction, thus enhancing the uniform mixing and reaction efficiency of the alkaline agent. Multiple pulse-type dry powder nozzles of the alkaline dry powder injection device are sealed and inserted through the side wall of the dechlorination chamber on the side where the inlet is located, and are longitudinally staggered with the oblique flow guide plates. Alkaline agent is sprayed within the independent reaction area between each pair of adjacent flow guide plates. The spray direction of the dry powder nozzles is opposite to the flue gas flow direction, forming a counter-current contact, maximizing the contact area and time, and significantly improving dechlorination efficiency.

[0012] In addition, a concentrating and sealing connector is installed at the connecting hole above the double-layer filter device. It is sealed and connected to the clean air chamber and isolated from the interlayer cavity. It is used to gather and guide the filtered airflow to ensure stable operation under negative pressure filtration conditions.

[0013] Option 2 (Method): A method for combined dechlorination and stratified filtration dust removal in a cement kiln bypass, comprising the following steps: Step S1 (Introduction and Cooling): The flue gas, which has undergone cyclone pre-dust removal and pipeline liquid cooling, and whose temperature has been reduced to 200-300℃, and contains fine dust with adhering crystalline chloride salts and HCl gas, is introduced into the filter box. 200-300℃ is selected as the process temperature window, taking into account the natural landing point of the preceding liquid cooling process, the upper temperature resistance limit of the high-temperature filter bag material, the safety margin of the acid dew point, and the stable reaction temperature range of commonly used alkaline dry powder, to ensure optimal overall performance in terms of equipment safety, process compatibility, and dechlorination efficiency.

[0014] Step S2 (Fine Chlorine Removal): After the flue gas enters the dechlorination chamber, alkaline dry powder (one or more of Ca(OH)2, NaHCO3, Na2CO3, CaO, and CaCO3) is injected in a counter-current pulse manner. The flue gas flows synchronously along an S-shaped path. The alkaline dry powder and the HCl gas in the flue gas come into counter-current contact and undergo a neutralization reaction within a temperature range of 200-300℃ to generate solid chloride salt particles, which enter the dust removal chamber along with the flue gas, thus achieving fine chlorine removal.

[0015] Step S3 (Layered Filtration): Under negative pressure adsorption, the flue gas passes through the outer filter screen, the interlayer cavity and the inner filter bag in sequence from the side to achieve layered fine filtration. Coarse dust and solid chloride particles are trapped in the outer filter screen, while fine dust is trapped in the inner filter bag. The filtered purified flue gas enters the clean air chamber and is transported to the next process.

[0016] Step S4 (Shockwave Cleaning and Flow Convergence): When the dust adhering to the filter bag accumulates to a set amount, shockwave backflushing is activated. The airflow is pulsed outward from the inside of the inner filter bag, causing the inner filter bag to expand locally and come into contact with the outer filter screen. This dynamically divides the interlayer cavity into several flow-limiting channels. The adhering dust is peeled off under the action of the backflushing airflow and falls directionally into the ash hopper through the flow-limiting channels. At the same time, the shockwave backflushing synchronously triggers the automatic opening of the linkage dust collection opening and closing structure at the bottom of the outer filter screen, forming a directional dust falling channel from the interlayer cavity to the ash hopper.

[0017] Step S5 (Reset Cycle): After the shock wave backflushing ends, the inner filter bag is passively reset, the linkage dust collection opening and closing structure automatically closes as the backflushing airflow disappears, the interlayer cavity returns to an integrated connected space, and the system enters the next round of negative pressure adsorption filtration, and the cycle alternates.

[0018] Compared with the prior art, the present invention has the following significant technical effects: 1. Integrated dechlorination and dust removal for high-efficiency fine dechlorination. This invention integrates the alkaline dry powder dechlorination process with the high-temperature filter bag dust removal process into the same device, making full use of the process temperature window of 200-300℃. Through the S-shaped flow channel and counter-current jet design, the contact reaction time between HCl gas and alkaline dry powder is significantly extended, significantly improving dechlorination efficiency. The generated solid chloride particles are then efficiently captured by the layered filtration system, achieving synergistic and efficient operation of dechlorination and dust removal.

[0019] 2. The adaptive beam shaping component enables dynamic control, significantly improving dust removal efficiency. Relying on the shock wave backflushing air pressure and the inherent elasticity of the arc-shaped frame, the adaptive beam shaping component automatically and dynamically switches the interlayer cavity between an "integrated large-volume flow space" and a "multi-flow-limiting channel guiding space" without the need for additional drive components. During the filtration stage, the interlayer cavity maintains a large-volume, low-resistance flow; during the dust removal stage, it is automatically divided into flow-limiting channels, effectively suppressing disordered dust movement and ash caking, ensuring that dust falls directionally and smoothly into the ash hopper without additional energy consumption.

[0020] 3. Layered fine filtration effectively extends filter bag lifespan. The outer filter screen traps coarse dust and solid chloride salts, while the inner filter bag focuses on high-precision fine dust filtration. This clear division of labor prevents solid chloride salts from clogging the pores of the inner filter bag, effectively protecting the filtration accuracy and extending its lifespan. The axial support frame and the annular elastic frame work together to prevent hard contact friction during negative pressure collapse and shock wave expansion, further extending the filter bag's lifespan.

[0021] 4. The linked dust collection opening and closing structure accommodates both operating conditions and prevents secondary dust generation. Relying on passive air pressure linkage, the linked dust collection opening and closing structure requires no additional drive and automatically adapts to both negative pressure filtration (closing and sealing to prevent air leakage and dust generation) and shockwave cleaning (opening and guiding airflow for smooth dust discharge), effectively eliminating secondary dust generation and improving dust collection reliability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the cut-out portion of the present invention; Figure 2 This is a schematic diagram of the structure of the dual-layer filtration device of the present invention; Figure 3 for Figure 2 Enlarged view of section I; Figure 4 This is a schematic diagram of the linkage dust collection opening and closing structure of the present invention; Figure 5 This is a top view of the internal structure of the present invention; Figure 6 This is a schematic diagram of the structure of the arc segment skeleton end during the resetting process of the present invention; Figure 7This is a schematic diagram of the internal structure of the dechlorination chamber of the present invention; Figure 8 This is a flowchart of the overall process path of the present invention; Figure 9 This describes the filtration and cleaning cycle of the dual-layer filtration device of the present invention.

[0023] Filter housing 10, alkaline dry powder injection device 20, double-layer filter device 30, dechlorination chamber 11, dust removal chamber 12, clean air chamber 13, connecting hole 14, dry powder nozzle 21, inner filter bag 31, outer filter screen 32, interlayer cavity 33, adaptive beam shaping component 34, stable reset structure 35, axial support frame 36, linked dust collection opening and closing structure 37, annular elastic frame 341, arc segment frame 3411, adsorption magnet 35 1. Valve plate 371, return spring 372, movable pressure-bearing linkage component 373, hollow dust removal limiting plate 374, central shaft 375, mounting cavity 38, flexible splicing piece 381, axial limiting mating part 39, partition plate 41, air inlet 42, air outlet 43, flow guide notch 411, S-shaped flow guide structure 44, oblique flow guide plate 441, wind-gathering sealing connection nozzle 50, negative pressure adsorption system 60, shock wave dust removal system 70, ash hopper 80. Detailed Implementation Example

[0024] In this embodiment, the high-temperature filter bag dust removal step of the cement kiln bypass dechlorination system is used. At this time, after the initial high-temperature flue gas has undergone cyclone pre-dust removal and pipeline liquid cooling treatment, the temperature has dropped to 200 to 300°C and most of the coarse dust has been removed. The remaining flue gas is mostly fine dust with crystalline chloride salts and trace amounts of HCl gas. The temperature of 200 to 300°C is a suitable reaction temperature range that takes into account the previous liquid cooling process, the upper limit of filter bag temperature resistance, and the safety margin of acid dew point. It can avoid the formation of strong acid mist due to the combination of HCl and water vapor below the acid dew point (<200°C), which would corrode the pipeline filter bag, etc. It can also avoid the temperature being too high (>300°C), which would exceed the stable reaction temperature range of commonly used alkaline dry powder (such as NaHCO3, which completely decomposes at about 270°C), and avoid exceeding the long-term temperature resistance limit of conventional filter bag materials. Therefore, this embodiment utilizes this feature to add a fine dechlorination step and integrates it with filter bag dust collection. At the same time, the dust collection structure is further improved to enhance its dust removal effect. For this purpose, a cement kiln bypass co-dechlorination and stratified filtration dust collector is provided.

[0025] The filter bag dust removal system can adsorb the remaining flue gas laterally into its interior. During the adsorption process, trace amounts of HCl gas are first removed by using dry ultrafine alkaline dry powder to adsorb and form solid chloride salts, thereby achieving fine chlorine removal. The solid chloride salts then move towards the filter bag body along with the flue gas containing chlorine fine dust to achieve the capture and filtration of solid dust particles. Finally, the dust is discharged through the shock wave cleaning system 70 of this system, achieving a dual high-efficiency synergistic operation of dust removal and fine chlorine removal.

[0026] Specifically, refer to Figure 1 The filter bag dust removal system includes a filter box 10, inside which a dechlorination chamber 11, a dust removal chamber 12, and a clean air chamber 13 are sequentially formed according to the flue gas flow direction. The dechlorination chamber 11 is sealed with an alkaline dry powder injection device 20 for injecting alkaline ultrafine dry powder, preferably Ca(OH)2 dry powder, to neutralize trace amounts of HCl gas in the flue gas, forming solid chloride salts. The dust removal chamber 12 is arrayed with multiple double-layer filter devices 30 (only one is shown in the figure for illustration), used to filter solid dust particles, achieving gas-solid separation and purifying the flue gas. The clean air chamber 13 is connected to a negative pressure adsorption system 60 and a shock wave cleaning system 70. The two are connected through a connecting hole 14 above the double-layer filter device 30, ensuring the flow of the negative pressure adsorption airflow and the reverse airflow of the cleaning system, thereby driving the flue gas to flow in a directional manner and performing pulse blowing dust removal on the filter bag surface.

[0027] The dual-layer filtration device 30 is a major improved design of the present invention, as described in the reference. Figure 2 , Figure 3 The filter comprises an inner filter bag 31 and an outer filter screen 32, with a cavity 33 formed between them. The inner filter bag 31 filters dust particles, while the outer filter screen 32 provides overall support and filters residual coarse dust in the flue gas. Preferably, the pore size of the outer filter screen 32 is set to be smaller than the particle size of solid chloride (CaCl2) to allow solid chloride to pass through. This design has the following advantages: it prevents solid chloride from clogging the smaller pores of the inner filter bag 31, protecting the high-precision filtration of the filter bag; combined with the high proportion of fine dust and the relatively low proportion of coarse dust and solid chloride, the distribution of dust particles is more balanced, ensuring effective filtration of solid chloride without affecting the filtration accuracy of fine dust; and the large pores and high rigidity of the outer filter screen 32 facilitate cleaning and improve the chloride removal effect.

[0028] Further, refer to Figure 2The inner wall of the inner filter bag 31 is provided with an adaptive beam shaping component 34, which is used to further support and shape the inner filter bag 31, and also to adaptively divide the interlayer cavity 33. During shock wave backflushing, the original integrated large-capacity space can be divided into multiple small-volume guiding intervals, thereby limiting the dust falling channel space, inhibiting dust movement, retention and ash accumulation. At the same time, during the negative pressure adsorption of flue gas, the integrated large-capacity space is still retained, reducing wind resistance and ensuring the flow of flue gas.

[0029] The adaptive beam shaping component 34 is the core innovation of this dual-layer filter device 30. (Refer to...) Figure 3 It includes multiple annular elastic skeletons 341 arranged along the axial direction. The annular elastic skeletons 341 are disposed on the inner wall of the inner filter bag 31 and are composed of multiple arc-segment skeletons 3411 spliced ​​together circumferentially. This embodiment is provided with four arc-segment skeletons 3411 (e.g., Figure 5 As shown, each of them is elastic, and the elastic force is less than the airflow force generated during shock wave backflushing. Therefore, when the shock wave backflushes, the two ends of the arc-shaped frame 3411 can be expanded outward, and the corresponding inner filter bag 31 can be deformed outward until it abuts against the inner wall of the outer filter screen 32. Through multiple continuous abutment points, an axial flow restriction channel is formed in the interlayer cavity 33, thereby reducing the effective flow volume and reducing the amount of dust moving in the circumferential direction and axial direction. At the same time, gaps are still maintained between the abutment points to achieve balanced interconnection of a small amount of airflow, avoiding problems such as local air blockage, increased resistance, and dead corners for dust removal caused by full enclosure.

[0030] The adaptive beam shaping component 34 also has the following advantages: relying on the pressure difference between the inside and outside of the filter bag generated by the shock wave backflushing and the elasticity of the arc frame 3411 itself, it can realize the adaptive dynamic switching of the contact and separation between the inner filter bag 31 and the outer filter screen 32 without the need for additional drive components. Moreover, the limiting guide only temporarily contacts and shapes during the dust removal process, and completely disengages during the filtration stage. Through this purely mechanical passive adaptation method, it takes into account both the needs of normal flow and instantaneous flow restriction. The structure is simplified and has no additional losses, and it is compatible with the continuous alternating filtration and dust removal cycle operation mode of this double-layer filter device 30.

[0031] Preferably, refer to Figure 2 The positions of the arc segments 3411 of the multiple annular elastic skeletons 341 are one-to-one, so the segment joints of the multiple annular elastic skeletons 341 can be aligned longitudinally, so that the ends of the multiple longitudinally corresponding arc segments 3411 and the contact points of the outer filter screen 32 can form a longitudinally straight flow-blocking structure. Therefore, the flow-limiting channel formed is also straight without turning points, which can ensure that the dust falls smoothly.

[0032] To ensure that the end of the arc segment frame 3411 can stably return to its original position after the shock wave backflush stops, a stable reset structure 35 is also provided (e.g., Figure 5 (As shown).

[0033] In this embodiment, reference Figure 3 , Figure 5 The stable reset structure 35 is disposed between adjacent ends of adjacent arc segment skeletons 3411 to provide a passive reset force. The sum of this force and the elastic force of the arc segment skeleton 3411 itself is less than the airflow force generated by the shock wave backflush. Preferably, it is achieved by magnetic attraction: including an adsorption magnet 351 and a magnetic adsorption layer formed on the end of the arc segment skeleton 3411 (the magnetic adsorption layer is not shown in the figure). The magnetic adsorption layer can be obtained by any method of forming stable magnetic features on the end of the arc segment skeleton 3411, such as coating with composite magnetic powder, magnetic patch bonding, integral molding of magnetic materials, etc.

[0034] Among them, reference Figure 6 During the resetting process of the arc-shaped frame 3411, due to its own weight, its resetting trajectory is a downward concave arc shape. Specifically, when it is far from the adsorption magnet 351, it moves towards the adsorption magnet 351 while drooping due to its own weight. As it moves radially and shortens the distance with the adsorption magnet 351, the magnetic attraction between the two increases, which can completely overcome its own weight. Therefore, it can adsorb the end of the arc-shaped frame 3411 in an upward oblique trajectory until the two are adsorbed and attached. During the process of the arc-shaped frame 3411 moving downward and then upward in an arc shape, it is equivalent to the end generating axial vibration. Therefore, it can shake off the dust on the filter bag at the corresponding outward expansion end during the shock wave backflushing.

[0035] In another embodiment (the structure of this embodiment is not shown in the figure), to further improve the dust removal effect at the corresponding end during shock wave backflushing, the stable reset structure 35 is implemented using a non-equivalent elastic spring, specifically a wave-type elastic sheet or a variable-diameter helical damping spring. Through its non-equivalent elastic deformation structure, low-frequency, micro-amplitude radial vibration is continuously generated during the slow rebound reset process. At the same time, combined with the axial vibration generated by its own weight, instantaneous rigid reset can be further avoided, removing the retained fine dust without additional energy consumption, and is compatible with the filter bag cleaning structure that can deform along with it.

[0036] To further improve the support and shape retention of the inner filter bag 31, and to prevent excessive inward collapse and shrinkage of the bag during negative pressure adsorption, as well as excessive outward expansion of the bag during shock wave cleaning, which would result in hard contact and frictional loss with the filter screen, thereby stabilizing the filter bag deformation range and optimizing the flue gas flow gap. (Reference) Figure 3 , Figure 5In this embodiment, multiple axial support frames 36 arranged at equal intervals along the circumference are also provided on the inner wall of the inner filter bag 31. The arrangement of the axial support frames 36 can also provide auxiliary positioning constraints for the annular elastic frame 341, reduce the stress load on the annular elastic frame 341, and allow its number to be reasonably and appropriately arranged without the need for dense addition.

[0037] Preferably, the axial support frame 36 is provided with four (e.g., Figure 5 As shown), it is interrupted when passing through the annular elastic skeleton 341, and the interruption is preferably at the stable reset structure 35.

[0038] This embodiment also includes a linkage-type dust collection opening and closing structure 37 (such as...). Figure 2 As shown), it is located at the bottom of the outer filter screen 32 and in front of the dust collection hopper 80 (as shown). Figure 1 As shown in the figure, it is used to coordinate with both negative pressure dust collection and shock wave dust removal, and can dynamically switch between opening and closing.

[0039] During the dust removal stage of negative pressure adsorption, the linkage dust collection opening and closing structure 37 remains closed, which can seal the bottom opening of the outer filter screen 32 and prevent the side-entering flue gas from leaking out from the bottom. Therefore, it constrains the flue gas flow direction in the interlayer cavity 33 and maintains the stability of the cavity negative pressure, preventing the bottom leakage and random flow that would stir up the settled dust in the ash hopper 80 and cause secondary dust. During the dust removal stage of shock wave backflushing, it automatically opens by relying on the reverse airflow, providing a downward directional falling channel for the blown-off dust, ensuring that the dust falls smoothly into the ash hopper 80. At the same time, it can balance the internal air pressure of the interlayer cavity 33, reduce the backflushing airflow loss, and optimize the dust removal efficiency. The entire structure relies on air pressure linkage to achieve passive opening and closing, without the need for additional driving components. The structure is simple and also adaptable to the continuous alternating filtration and dust removal cycle operation mode of the double-layer composite structure of this invention.

[0040] Specifically, refer to Figure 4The linkage-type dust collection opening and closing structure 37 includes a valve plate 371, a return spring 372, a movable pressure-bearing linkage component 373, and a hollow dust removal limiting plate 374. The valve plate 371 can be detachably and properly sealed with the opening at the bottom of the outer filter screen 32. The return spring 372 is sleeved on the central shaft 375 at the upper end of the valve plate 371. The movable pressure-bearing linkage component 373 is located at the upper end of the central shaft 375 and can float axially with air pressure. It also receives the airflow impact from the bottom of the inner filter bag 31, thereby causing the central shaft 375 to move downwards and compress and reset. Spring 372 enables automatic linkage opening of valve plate 371. The hollowed-out dust-removing limiting plate 374 is movably sleeved at one end with the lower part of the central shaft 375, and fixedly connected to the inner wall of the outer filter screen 32 at the other end. It employs a multi-rod circumferential arrangement, which not only limits and supports the bottom end of the return spring 372, constraining the movement trajectory of the central shaft 375 and the return spring 372, but also utilizes the gaps between the rods to form a dust-falling channel, allowing dust to smoothly pass through the hollowed-out dust-removing limiting plate 374 and enter the ash hopper 80, achieving a dual function of limiting and guiding, and smooth dust removal. When the shock wave backflushing ends, the airflow force on the movable pressure-bearing linkage 373 disappears. At this time, the movable pressure-bearing linkage 373, the central shaft 375, and the valve plate 371 move upwards under the rebound force of the return spring 372 and return to the closed state.

[0041] To further improve the installation fit of the arc segment frame 3411 and ensure its installation stability and stable operation during expansion, this embodiment also has the following two settings (such as... Figure 3 , Figure 6 (As shown).

[0042] The annular elastic skeleton 341 is installed in the mounting cavity 38 of the inner filter bag 31. The mounting cavity 38 is composed of flexible splicing pieces 381 connected to the inner filter bag 31 at both ends. The flexible splicing pieces 381 are separated at the corresponding two adjacent arc segment skeletons 3411 to facilitate radial expansion or repositioning of the ends.

[0043] The inner wall of the outer filter screen 32 is also provided with an axial limiting fitting part 39 at each corresponding annular elastic skeleton 341, so that when the end of the arc segment skeleton 3411 expands outward, it is embedded into the axial limiting fitting part 39 to limit its axial displacement, thereby ensuring the stability of the flow-limiting channel formed by multiple contact points and the reliability of the dust flow recovery process.

[0044] This invention also makes further improvements to the fine dechlorination operation, such as... Figure 7 As shown, the specific structure is as follows.

[0045] To ensure sufficient reaction of HCl gas within the dechlorination chamber 11 and improve dechlorination efficiency, a partition 41 is integrated into the dust removal chamber 12. This partition 41 is vertically positioned in the center of the chamber, separating the inlet 42 and outlet 43 of the dust removal chamber 12 on either side. A guide gap 411 is formed at one end of the partition 41 through a gap, creating an isosceles triangle with the inlet 42 and outlet 43. This causes the flue gas entering through the inlet 42 to first flow through the guide gap 411 to the other side and then move in the opposite direction to the outlet 43 before entering the dust removal chamber 12. This extends the flow path of the flue gas and increases the reaction time of the HCl gas.

[0046] Furthermore, the aforementioned baffle 41 structure can be replaced or further modified. In this embodiment, the latter is preferred. Specifically, an S-shaped flow guide structure 44 is provided in the space formed between the cavity wall and the baffle 41 on the side near the air inlet 42. This structure includes multiple longitudinally staggered and relatively arranged inclined flow guide plates 441 in this space to form an S-shaped flue gas channel, further extending the reaction time. At the same time, by setting a certain inclination angle and continuously changing the direction, the flue gas forms a rotating flow, which can enhance the mixing effect of HCl gas and alkaline agent, improve the reaction efficiency, and strengthen the dechlorination effect.

[0047] While extending the path to increase time and ensure sufficient reaction, it is also necessary to consider that the alkaline agent content is sufficient and preferably evenly distributed in the cavity. Therefore, the alkaline dry powder spraying device 20 is optimized as follows.

[0048] Specifically, the alkaline dry powder injection device 20 includes multiple pulse-type dry powder nozzles 21, which are sealed and penetrate the side wall of the dechlorination chamber 11 on the side where the air inlet 42 is located. The multiple dry powder nozzles 21 and multiple inclined guide plates 441 disposed on this side wall are longitudinally staggered to allow the injection of alkaline agent between every two adjacent inclined guide plates 441 on this side. This arrangement utilizes the multiple inclined guide plates 441 to form multiple small, independent reaction zones. By injecting alkaline agent into each zone, the contact area between the agent and HCl gas is increased, thereby significantly improving the reaction efficiency.

[0049] Preferably, the dry powder nozzle 21 sprays at an angle, with its spray direction opposite to the flue gas flow direction, so as to form a counter-current contact with the flue gas, increase the contact area and contact time between the two, enhance the mixing contact effect, and improve the reaction efficiency.

[0050] In this embodiment, the air inlet 42 and the air outlet 43 are located on the lower parts of opposite sides of the dust removal chamber 12, and the air inlet 42 is also the air inlet of the filter box 10. This allows the flue gas entering the dust removal chamber 12 to flow upwards and laterally into the interior from the bottom of the double-layer filter device 30, ensuring that the filtered dust is evenly distributed throughout the double-layer filter device 30 as much as possible. Correspondingly, the flow guide notch 411 is located above the partition 41; the inclined flow guide plate 441 is arranged obliquely upwards to form an upward flow guide for the flue gas; and the dry powder nozzle 21 is arranged obliquely downwards to spray.

[0051] Multiple dry powder nozzles 21, arranged in a staggered pattern with the inclined guide vane 441, are grouped together. In practical applications, the number of groups of dry powder nozzles 21 can be adjusted according to factors such as the volume of the dechlorination chamber 11 and the location of the air inlet 42. (Only one group is shown in the figure for illustrative purposes.) In this embodiment, a wind-concentrating sealing connector 50 is preferably provided at the connecting hole 14 (e.g., ...). Figure 2 As shown in the figure, it is sealed and connected to the clean air chamber 13 and isolated from the interlayer cavity 33. It is used to gather and filter and guide the airflow to ensure stable operation under negative pressure filtration conditions.

[0052] Refer to all attached diagrams Figures 1 to 9 The specific working process of this embodiment is as follows: 1. Fine dechlorination operation: The flue gas enters the filter box 10 from the inlet 42, which is also the dechlorination chamber 11. Then it flows along the S-shaped channel formed by multiple inclined guide plates 441. During this process, the dry powder nozzle 21 sprays alkaline agent powder into the dust removal chamber 12 at a certain pulse frequency, so that it reacts with the trace amount of HCl gas remaining in the flue gas to generate solid chloride salt particles (CaCl2), which continue to flow with the flue gas until they pass through the guide gap 411 and the outlet 43 in sequence, and then enter the dust removal chamber 12.

[0053] 2. High-efficiency dust removal operation: The flue gas entering the dust removal chamber 12 flows upward and passes laterally through the outer filter screen 32, the interlayer cavity 33 and the inner filter bag 31 in sequence under the action of the negative pressure adsorption system 60, thereby achieving dust filtration and purifying the flue gas. The purified flue gas continues to flow upward from the hollow part of the inner filter bag 31, passes through the air-gathering sealing connection nozzle 50 and enters the clean air chamber 13. The purified flue gas is then transported to the next process by the negative pressure adsorption system 60.

[0054] During the negative pressure adsorption stage, the coarse dust remaining in the flue gas and the newly generated solid chloride particles adhere to the outer filter screen 32, while a large amount of fine dust adheres to the inner filter bag 31. Under the support and shaping of the axial support frame 36 and the annular elastic frame 341, the inner filter bag 31 has a small degree of inward collapse and shrinkage. Therefore, it can maintain a stable gap in the interlayer cavity 33 and effectively maintain the filtration area of ​​the filter bag. This ensures stable ventilation in the interlayer cavity 33, avoids the filter bag from sticking to the wall and blocking the flow, and also avoids local folds and stacking of the filter bag, thereby ensuring the dust collection and filtration effect.

[0055] After a certain period of filtration, when a large amount of dust has adhered, the system automatically activates the shockwave cleaning system 70 to clean the dust. During this process, the shockwave cleaning system 70 sprays airflow in pulse form from the center of the filter bag outward, thereby blowing out the fine dust adhering to the filter bag and temporarily locking it in the interlayer cavity 33. When the backflushing stops, the dust falls due to its own weight and is collected in the bottom ash hopper 80 through the self-opening linkage dust collection opening and closing structure 37. At the same time, the backflushing airflow also blows a small amount of coarse dust and solid chloride salts on the outer filter screen 32 into the dust collection chamber 12 and collects them in the bottom ash hopper 80.

[0056] During the outward ejection of airflow, the ends of the arc-shaped skeletons 3411 on each annular elastic skeleton 341 will expand and deform outward due to the force of the airflow, and embed into the axial limiting fitting part 39 to fit and abut against it. These multiple continuous fitting and abutting points can form multiple parallel longitudinal flow-blocking structures, thereby forming multiple adjacent and longitudinally straight flow-limiting channels in sequence. This divides the original integrated large-capacity sandwich cavity 33 into multiple independent flow-guiding intervals, greatly reducing the space for lateral airflow diffusion and vortex formation, thereby constraining the airflow direction, reducing the range of disordered dust movement, and improving the stability of filtration and dust removal. At the same time, the axial support skeleton 36 still plays its role in supporting and shaping the filter bag. Therefore, even under the action of pulsed airflow, the degree of outward expansion deformation of the filter bag body is very small, which can avoid frictional loss caused by hard contact with the outer filter screen 32.

[0057] 3. Return to original position: After the shock wave cleaning is completed, the airflow force it generates disappears. Under its own elasticity and the external action of the stable reset structure 35, the end of the arc segment skeleton 3411 returns to its initial normal position and restores the integrated large volume state of the interlayer cavity 33, ready for the next negative pressure dust removal and chlorine removal operation.

[0058] The system selects 200 to 300°C as the temperature window for fine dechlorination, which is the result of considering the following process chain conditions: (1) the natural temperature drop of the flue gas after the preceding cyclone pre-dust removal and pipeline liquid cooling treatment; (2) the long-term temperature resistance limit of high-temperature filter bag materials (such as P84, PTFE membrane) is usually no more than 260 to 280°C; (3) to avoid acid mist corrosion below the sulfuric acid dew point range (usually 120 to 150°C); (4) to take into account the stable reaction temperature range of commonly used alkaline dry powders (such as NaHCO3 which decomposes completely at 270°C, and Ca(OH)2 which maintains good reactivity in this temperature range). Those skilled in the art will understand that, under the aforementioned constraints, 200 to 300°C is a suitable engineering range that simultaneously satisfies equipment safety, process compatibility, and dechlorination efficiency.

[0059] The above description is merely a specific example of the present invention and does not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and detail without departing from the principles and structure of the present invention; however, these modifications and changes based on the spirit of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A cement kiln bypass co-chlorination and stratified filtration dust collector, characterized in that, The system includes a filter housing (10), within which a dechlorination chamber (11), a dust removal chamber (12), and a clean air chamber (13) are sequentially formed along the flue gas flow direction. An alkaline dry powder injection device (20) is installed in the dechlorination chamber (11). Multiple double-layer filter devices (30) are installed in the dust removal chamber (12). Each double-layer filter device (30) includes an inner filter bag (31), an outer filter screen (32) located outside the inner filter bag (31), and an adaptive beam shaping assembly disposed on the inner wall of the inner filter bag (31). 34), an interlayer cavity (33) is formed between the inner filter bag (31) and the outer filter screen (32); the clean air cavity (13) is connected to a negative pressure adsorption system (60) and a shock wave cleaning system (70); the adaptive beam shaping component (34) is configured to: drive the inner filter bag (31) to expand locally and abut against the outer filter screen (32) when the shock wave cleaning system (70) backflushes, dividing the interlayer cavity (33) into several flow-limiting channels; reset after backflushing, so that the interlayer cavity (33) returns to an integrated connected space.

2. The dust collector according to claim 1, characterized in that, The adaptive beam shaping component (34) includes multiple annular elastic skeletons (341) spaced apart along the axial direction of the inner filter bag (31). Each annular elastic skeleton (341) is composed of multiple arc-shaped skeletons (3411) spliced ​​together circumferentially. The arc-shaped skeletons (3411) are elastic, and their elastic force is less than the airflow force generated when the shock wave blows back. The positions of the arc-shaped skeletons (3411) of the multiple annular elastic skeletons (341) correspond one-to-one, so that the segment joints of the multiple annular elastic skeletons (341) are aligned longitudinally.

3. The dust collector according to claim 2, characterized in that, A stable reset structure (35) is provided between adjacent ends of the adjacent arc segment skeleton (3411) to provide a passive reset force. The sum of this force and the elastic force of the arc segment skeleton (3411) itself is less than the airflow force generated by the shock wave backflush. The stable reset structure (35) is a magnetic attraction structure including an adsorption magnet (351) and a magnetic adsorption layer formed at the end of the arc segment skeleton (3411), or a non-equivalent elastic spring that generates low-frequency micro-amplitude radial jitter and vibration during the reset process.

4. The dust collector according to claim 2, characterized in that, The inner wall of the inner filter bag (31) is also provided with a plurality of axial support skeletons (36) arranged circumferentially. The axial support skeletons (36) are separated at the annular elastic skeleton (341). The annular elastic skeleton (341) is installed in the mounting cavity (38) of the inner filter bag (31). The mounting cavity (38) is formed by connecting the two ends of the flexible splicing piece (381) to the inner filter bag (31). The flexible splicing piece (381) is separated at the segmentation of the corresponding two adjacent arc segment skeletons (3411). The inner wall of the outer filter screen (32) is provided with an axial limiting fitting part (39) at each annular elastic skeleton (341) for axially limiting the arc segment skeleton (3411) after it expands outward.

5. The dust collector according to claim 1, characterized in that, The pore size of the outer filter (32) is smaller than the particle size of the solid chloride salt particles generated by the reaction of alkaline dry powder and HCl; the bottom of the outer filter (32) is provided with a linkage dust collection opening and closing structure (37), which is configured to: remain closed during the negative pressure adsorption stage to block the bottom opening of the outer filter (32); and automatically open during the shock wave backflushing stage to form a dust falling channel by relying on the reverse airflow.

6. The dust collector according to claim 5, characterized in that, The linkage dust collection opening and closing structure (37) includes a valve plate (371), a return spring (372), a movable pressure-bearing linkage component (373), and a hollow dust removal limiting plate (374). The valve plate (371) can be separated and sealed with the opening at the bottom of the outer filter screen (32). The return spring (372) is sleeved on the central shaft (375) at the upper end of the valve plate (371). The movable pressure-bearing linkage component (373) is set at the upper end of the central shaft (375) and bears the airflow impact at the bottom of the inner filter bag (31). One end of the hollow dust removal limiting plate (374) is movably sleeved with the lower part of the central shaft (375), and the other end is fixedly connected to the inner wall of the outer filter screen (32).

7. The dust collector according to claim 1, characterized in that, The dust removal chamber (12) is provided with an air inlet (42) and an air outlet (43) on opposite sides of the lower part. A partition (41) is provided inside the dust removal chamber (12). The partition (41) separates the air inlet (42) and the air outlet (43) on both sides. A gap is left between one end of the partition (41) and the chamber wall to form a flow guide notch (411). The flow guide notch (411) forms an isosceles triangle structure with the air inlet (42) and the air outlet (43). An S-shaped flow guide structure (44) is provided between the chamber wall near the air inlet (42) and the partition (41). The S-shaped flow guide structure (44) includes multiple longitudinally staggered and relatively arranged oblique flow guide plates (441).

8. The dust collector according to claim 7, characterized in that, The alkaline dry powder injection device (20) includes multiple pulse dry powder nozzles (21), which are sealed and penetrate the side wall of the dechlorination chamber (11) on the side of the air inlet (42), and the multiple dry powder nozzles (21) are longitudinally staggered with multiple inclined guide plates (441) on the side wall; the injection direction of the dry powder nozzles (21) is opposite to the flue gas flow direction.

9. A method for combined dechlorination and stratified filtration dust removal in a cement kiln bypass, characterized in that, Includes the following steps: S1. Introduction and cooling: The flue gas, which has been pre-dust removed by cyclone and liquid-cooled in pipeline, and whose temperature has been reduced to 200-300℃ and contains fine dust with adhering crystalline chloride salts and HCl gas, is introduced into the filter box (10). S2, fine dechlorination: After the flue gas enters the dechlorination chamber (11), alkaline dry powder is pulsed into the flue gas. The alkaline dry powder and the HCl gas in the flue gas undergo a neutralization reaction in the temperature range of 200-300℃ to generate solid chloride salt particles, which enter the dust removal chamber (12) along with the flue gas. S3, Layered Filtration: Under the action of negative pressure adsorption, the flue gas passes through the outer filter screen (32), the interlayer cavity (33) and the inner filter bag (31) in sequence. Coarse dust and solid chloride salt particles are trapped in the outer filter screen (32), and fine dust is trapped in the inner filter bag (31). The filtered purified flue gas enters the clean air chamber (13) and is transported to the next process. S4, Shockwave cleaning and jetting: When the dust adhering to the filter bag reaches the set amount, the shockwave backflushing is activated, causing the airflow to pulse outward from the inside of the inner filter bag (31), driving the inner filter bag (31) to expand locally and come into contact with the outer filter screen (32), dividing the interlayer cavity (33) into several flow-limiting channels. The adhering dust peels off under the action of the backflushing airflow and falls directionally into the ash hopper (80) through the flow-limiting channels; S5, Reset Cycle: After the shock wave backflushing ends, the inner filter bag (31) is passively reset, the interlayer cavity (33) is restored to an integrated connected space, and the next round of negative pressure adsorption filtration in S3 is started, and the cycle is alternated.

10. The method according to claim 9, characterized in that, In step S2, the alkaline dry powder is one or more of Ca(OH)2, NaHCO3, Na2CO3, CaO, and CaCO3, and its injection direction is opposite to the flue gas flow direction to form a counter-current flow, and the flue gas flows along an S-shaped path in the dechlorination chamber (11); in step S4, the shock wave backflushing synchronously triggers the opening of the linkage dust collection opening and closing structure (37) at the bottom of the outer filter screen (32), forming a dust falling channel from the interlayer cavity (33) to the ash hopper (80); in step S5, the linkage dust collection opening and closing structure (37) automatically closes as the backflushing airflow disappears.

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