Cement kiln dust removal and denitration integrated device

Abstract

The present application relates to a kind of cement kiln dust removal denitration integrated device, by import flue with the preheater of cement production line connection.The device includes electric precipitator and denitration reactor being communicated.Electric precipitator includes dust removal bin, dust removal hopper, anode frame equipped with swingable anode plate and cathode frame equipped with swingable cathode wire, dust removal bin extends along vertical direction, its top is communicated import flue, dust removal hopper is connected to the bottom of dust removal bin, multiple anode frame and multiple cathode frame are staggered and arranged at equal intervals in dust removal bin.Denitration reactor includes reaction bin, reaction hopper, catalyst layer, rectifier layer and ash cleaning device, reaction bin extends along vertical direction, reaction hopper is connected to the bottom of reaction bin, catalyst layer is arranged in reaction bin, rectifier layer is arranged in reaction bin and below catalyst layer, and ash cleaning device is used to clean the bottom surface of denitration catalyst.Among them, the flue gas in dust removal bin flows from top to bottom, and the flue gas in reaction bin flows from bottom to top.

Description

Technical Field

[0001] This invention relates to the field of cement flue gas treatment, and more specifically, to an integrated dust removal and denitrification device for cement kilns. Background Technology

[0002] SCR (Selective Catalytic Reduction) denitrification technology is currently the mainstream technology for achieving ultra-low NOx emissions from cement kilns. However, the dust concentration in the flue gas from cement kilns is as high as 80–120 g / Nm³. 3 Furthermore, the dust contains a high content of alkaline earth metals and is characterized by high viscosity, strong adhesion, and small particle size. Direct entry of this type of high-dust-content flue gas into the SCR denitrification reactor can easily lead to problems such as catalyst blockage and wear. Therefore, considering the adverse effects of dust on the catalyst is crucial to the cement denitrification process.

[0003] Currently, the mainstream SCR denitrification processes for cement are high-temperature and high-dust, high-temperature and medium-dust, and high-temperature and low-dust SCR denitrification technologies.

[0004] The high-temperature, high-dust SCR denitrification process involves placing the SCR denitrification reactor directly at the outlet of the C1 preheater without a dust removal device. In this approach, the catalyst is highly susceptible to dust accumulation or blockage. Furthermore, fluctuations in upstream operating conditions can cause significant dust buildup on the catalyst surface, leading to blockage, wear, and deactivation, thus affecting the entire system's operation. To alleviate catalyst blockage, continuous sootblowing with a rake-type compressed air blower is required, resulting in high energy consumption and operating costs.

[0005] The high-temperature, medium-dust SCR denitrification process uses a horizontal electrostatic precipitator installed at the front end of the SCR denitrification reactor. The gas enters the SCR denitrification reactor after dust removal. This approach solves the problem of high dust content in the flue gas within the catalyst. However, the electrostatic precipitator is a horizontal structure with horizontal air intake, resulting in a large overall footprint, high system operating resistance, and the need for a separate rake-type compressed air blower for continuous soot blowing. This leads to high energy consumption, high system resistance, high operating costs, and a large footprint.

[0006] The high-temperature, low-dust SCR denitrification process uses high-temperature metal filter bags for dust collection at the front end of the SCR denitrification reactor. This removes the vast majority of dust from the flue gas, reducing the dust concentration entering the SCR denitrification process to the mg level. This solves the problems of catalyst wear and clogging, and allows for the use of catalysts with smaller pitches. However, the overall cost of metal filter bags is high, they occupy a large area, and because cement dust particles are small, they easily embed themselves in the filter bags. As operating time increases, the filter bag resistance rises rapidly, resulting in high system resistance, high operating costs, and high maintenance costs. Summary of the Invention

[0007] The purpose of this invention is to provide an integrated dust removal and denitrification device for cement kilns to solve the problems mentioned in the background art.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0009] This invention provides an integrated dust removal and denitrification device for cement kilns. It connects to the preheater of a cement production line via an inlet flue. An ammonia injection device is installed on the inlet flue. The device includes: an electrostatic precipitator comprising a dust collection chamber, a dust collection hopper, an anode frame with swingable anode plates, and a cathode frame with swingable cathode wires. The dust collection chamber extends vertically, its top connected to the inlet flue, and the dust collection hopper connected to and communicating with the bottom of the dust collection chamber. Multiple anode frames and multiple cathode frames are arranged alternately at equal intervals within the dust collection chamber. A denitrification reactor includes a reaction chamber, a reaction hopper, a catalyst layer, a rectifying layer, and a dust removal device. The reaction chamber extends vertically. The reaction ash hopper is connected to the bottom of the reaction chamber and communicates with the reaction chamber. The catalyst layer is disposed inside the reaction chamber and includes a denitrification catalyst. The catalyst layer has multiple layers spaced vertically. The rectifying layer is disposed inside the reaction chamber and below the catalyst layer. The rectifying layer has multiple vertically extending rectifying holes evenly distributed on it. The dust removal device is disposed inside the reaction chamber and is used to clean the bottom surface of the denitrification catalyst. The dust removal chamber and the reaction chamber are arranged adjacent to each other and have a connecting port. The flue gas in the dust removal chamber flows from top to bottom and enters the reaction chamber through the connecting port. The flue gas in the reaction chamber flows from bottom to top.

[0010] In some embodiments of this application, the dust removal chamber and the reaction chamber are integrally connected; a partition is provided between the dust removal chamber and the reaction chamber, the partition serving as a common sidewall between the dust removal chamber and the reaction chamber, and the communication opening is provided on the partition.

[0011] In some embodiments of this application, the communication port is located below the anode frame and the cathode frame in the dust removal chamber, and below the rectifier layer in the reaction chamber. The reaction chamber is also provided with a flue gas outlet located above the catalyst layer.

[0012] In some embodiments of this application, both the anode plate and the cathode wire extend vertically; multiple anode plates on the anode frame and cathode wires on the cathode frame are arranged side-by-side at intervals.

[0013] In some embodiments of this application, the denitrification reactor further includes a guide vane; the guide vane is disposed inside the reaction chamber, below the rectifying layer, and close to the communication port; the end of the guide vane close to the communication port and the end away from the communication port are inclined upwards; multiple guide vanes are provided at vertical intervals, and the inclination angle of the guide vanes gradually decreases from top to bottom.

[0014] In some embodiments of this application, the integrated dust removal and denitrification device for cement kilns further includes a dust interceptor located at the communication port.

[0015] In some embodiments of this application, the integrated dust removal and denitrification device for cement kilns further includes an ash discharge machine; the ash discharge machine is used to receive the dust discharged from the bottom outlet of the dust removal ash hopper and the dust discharged from the bottom outlet of the reaction ash hopper, and discharge the dust to the raw material silo.

[0016] In some embodiments of this application, the reaction chamber is connected to a waste heat boiler via an outlet flue.

[0017] As can be seen from the above technical solutions, the embodiments of the present invention have at least the following advantages and positive effects:

[0018] In the integrated dust removal and denitrification device for cement kilns in this embodiment of the invention, the high-temperature flue gas from the preheater of the cement production line enters the dust removal chamber of the electrostatic precipitator through the inlet flue.

[0019] Both the dust removal chamber and the reaction chamber extend vertically, meaning they are both vertical structures. Furthermore, the dust removal chamber and the reaction chamber are arranged adjacent to each other, which greatly reduces the floor space occupied by the electrostatic precipitator and the denitrification reactor.

[0020] The flue gas enters from the top of the dust collection chamber, which reduces the number of bends used to connect the dust collection chamber and the preheater, allowing the flue gas from the preheater to flow smoothly into the dust collection chamber and reducing system resistance.

[0021] The flue gas flows from top to bottom within the dust collection chamber. High-voltage discharge occurs on the cathode wires inside the chamber, separating charged anionic and cation-carrying dust ions. Cation-carrying dust is adsorbed by the cathode wires, while anion-carrying dust is adsorbed by the anode plates. Since both the anode plates and cathode wires can oscillate, they swing under the influence of the airflow, shaking off the dust onto the anode plates and cathode wires into the dust collection hopper. This eliminates the need for a vibrating device to vibrate the anode plates and cathode wires, reducing power consumption and maintenance workload during operation.

[0022] After being treated by the electrostatic precipitator, the flue gas enters the reaction chamber through the connecting port. Inside the chamber, the flue gas passes through a rectifying layer and multiple catalyst layers from bottom to top before exiting through the exhaust port. When passing through the rectifying layer, multiple vertically extending rectifying holes are evenly distributed on it. These holes distribute the flue gas flow evenly, and the rectification of the flue gas by these holes ensures that it flows vertically towards the denitrification catalyst in the catalyst layers, perpendicular to the bottom surface of the catalyst. Because the denitrification catalyst has a porous structure, when the flue gas passes through the bottom catalyst layer, the catalyst can block most of the dust in the flue gas at its bottom surface, reducing the concentration of dust entering subsequent catalyst layers and thus preventing clogging and wear of the denitrification catalyst in those layers. The dust collected on the bottom of the denitrification catalyst can also be cleaned using a dust removal device. After being cleaned, the dust falls into the ash hopper for collection, giving the bottom catalyst layer a pre-dust removal function. Combined with the front-end electrostatic precipitator that has already removed a large amount of dust, the system resistance is reduced, ensuring the stability and reliability of the denitrification reaction. At the same time, the investment and operating costs are lower, and the entire device is more energy-efficient and carbon-reducing. Attached Figure Description

[0023] Various objects, features, and advantages of the invention will become more apparent from the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings. The drawings are merely illustrative of the invention and are not necessarily drawn to scale. In the drawings, the same reference numerals always denote the same or similar parts.

[0024] in:

[0025] Figure 1 This is a schematic diagram of the structure of an integrated dust removal and denitrification device for cement kilns according to an embodiment of the present invention.

[0026] The following are explanations of the reference numerals in the attached drawings: 1. Cement rotary kiln; 2. Preheater; 30. Inlet flue; 3. Electrostatic precipitator; 31. Dust collection bin; 32. Dust collection hopper; 33. Anode frame; 34. Cathode frame; 40. Outlet flue; 4. Denitrification reactor; 41. Reaction chamber; 42. Reaction hopper; 43. Catalyst layer; 44. Rectifying layer; 45. Ash removal device; 46. Baffle plate; 461. Connecting port; 47. Guide vane; 5. Dust interceptor; 6. Ash discharge machine; 7. Waste heat boiler; 8. Fan; 9. Ammonia injection grid. Detailed Implementation

[0027] Although the invention can be readily embodied in various forms, only some specific embodiments are shown in the accompanying drawings and will be described in detail in this specification. It is understood that this specification should be regarded as an exemplary illustration of the principles of the invention and is not intended to limit the invention to what is described herein.

[0028] Therefore, a feature pointed out in this specification is used to illustrate one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. While certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0029] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various elements of the invention are relative rather than absolute. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the descriptions of the positions of these elements change, these directional indications also change accordingly.

[0030] Please see Figure 1 This invention provides an integrated dust removal and denitrification device for cement kilns, which is connected to the preheater 2 of the cement production line via an inlet flue 30. An ammonia injection grille 9 is installed on the inlet flue 30. Specifically, the preheater 2 is connected to the outlet of the cement rotary kiln, and the inlet flue 30 is connected to the top of the preheater 2 and the integrated dust removal and denitrification device.

[0031] The integrated dust removal and denitrification device for cement kilns includes an electrostatic precipitator 3 and a denitrification reactor 4.

[0032] The electrostatic precipitator 3 includes a dust collection chamber 31, a dust collection hopper 32, an anode frame 33 equipped with swingable anode plates, and a cathode frame 34 equipped with swingable cathode wires. The dust collection chamber 31 extends vertically, and the top of the dust collection chamber 31 is connected to the top of the preheater 2. The dust collection hopper 32 is connected to the bottom of the dust collection chamber 31 and communicates with the dust collection chamber 31. Multiple anode frames 33 and multiple cathode frames 34 are arranged alternately at equal intervals inside the dust collection chamber 31.

[0033] The denitrification reactor 4 includes a reaction chamber 41, a reaction ash hopper 42, a catalyst layer 43, a rectifier layer 44, and a dust removal device 45. The reaction chamber 41 extends vertically. The reaction ash hopper 42 is connected to the bottom of the reaction chamber 41 and communicates with the reaction chamber 41. The catalyst layer 43 is located inside the reaction chamber 41 and includes a denitrification catalyst. The catalyst layer 43 has multiple layers spaced vertically. The rectifier layer 44 is located inside the reaction chamber 41 and below the catalyst layer 43. The rectifier layer 44 has multiple vertically extending rectifier holes evenly distributed on it. The dust removal device 45 is located inside the reaction chamber 41 and is used to clean the bottom surface of the denitrification catalyst.

[0034] The dust removal chamber 31 and the reaction chamber 41 are arranged adjacent to each other and are connected by a connecting port 461. The flue gas in the dust removal chamber 31 flows from top to bottom and enters the reaction chamber 41 through the connecting port 461. The flue gas in the dust removal chamber 31 flows from bottom to top.

[0035] Through the above structural design, the high-temperature flue gas from the cement rotary kiln 1 exchanges heat with the cement raw materials through the preheater 2, and the ammonia injection device atomizes the ammonia water through compressed air and injects it into the inlet flue 30 for evaporation and mixing with the flue gas.

[0036] Both the dust removal chamber 31 and the reaction chamber 41 extend vertically, meaning that both the dust removal chamber 31 and the reaction chamber 41 are vertical structures. Furthermore, the dust removal chamber 31 and the reaction chamber 41 are arranged adjacent to each other, which greatly reduces the floor space occupied by the electrostatic precipitator 3 and the denitrification reactor 4.

[0037] The flue gas enters from the top of the dust collection chamber 31, which reduces the number of bends used to connect the dust collection chamber 31 and the preheater 2. This facilitates the smooth entry of the flue gas from the preheater 2 into the dust collection chamber 31, reduces system resistance, and increases the flow velocity of the flue gas in the dust collection chamber 31. Under the same flow requirements, the cross-sectional area of ​​the dust collection chamber 31 can be smaller, further reducing the footprint of the electrostatic precipitator 3.

[0038] The flue gas in the dust collection chamber 31 flows from top to bottom. The cathode wire 34 within the dust collection chamber 31 undergoes high-voltage discharge, separating the charged anionic and cation-carrying dust ions entering the chamber. Cation-carrying dust is adsorbed by the cathode wire 34, while anion-carrying dust is adsorbed by the anode plate 33. Since both the anode plate 33 and the cathode wire 34 are oscillating within the dust collection chamber 31, they oscillate under the influence of the airflow, shaking off the dust onto the anode plate 33 and cathode wire 34 and depositing it into the dust collection hopper 32. This eliminates the need for a tapping device to beat the anode plate 33 and cathode wire 34, effectively reducing the volume of the dust collection chamber 31, decreasing the footprint of the electrostatic precipitator 3, and reducing the power consumption during operation.

[0039] After being cleaned by the electrostatic precipitator 3, the flue gas enters the reaction chamber 41 through the connecting port 461. Inside the reaction chamber 41, the flue gas passes through the rectifying layer 44 and multiple catalyst layers 43 from bottom to top before exiting the reaction chamber 41 through the exhaust port. When passing through the rectifying layer 44, which has multiple vertically extending rectifying holes evenly distributed on it, the flue gas flows vertically under the rectification of these holes, ensuring that it is blown towards the denitrification catalyst in the catalyst layer 43 in a direction perpendicular to the bottom surface of the catalyst. Because the denitrification catalyst has a porous structure, when the flue gas passes through the bottom catalyst layer 43, the denitrification catalyst can block most of the dust in the flue gas at the bottom surface, reducing the concentration of dust entering subsequent catalyst layers 43 and thus preventing clogging and wear of the denitrification catalyst in the subsequent catalyst layers 43. The dust collected on the bottom surface of the denitrification catalyst can also be cleaned by the dust removal device 45. After being cleaned, the dust falls into the ash hopper for collection, so that the bottom catalyst layer 43 has a pre-dust removal function. Combined with the front-end electrostatic precipitator 3, which has already removed a large amount of dust, the system resistance is reduced, ensuring the stability and reliability of the denitrification reaction. At the same time, the investment and operating costs are lower, and the whole device is more energy-efficient and carbon-reducing.

[0040] It should be noted that the preheater 2 has a certain height, and the outlet of the preheater 2 is located at the top. In related technologies, a horizontal electrostatic precipitator 3 is used. When the outlet of the preheater 2 is connected to the horizontal electrostatic precipitator 3, at least one U-shaped pipe and one L-shaped pipe are required. The number of bends is relatively large, which increases the resistance to flue gas flow. In addition, the flue gas enters the horizontal electrostatic precipitator 3 laterally. Due to the large number of bends, the area occupied by the dust collection chamber 31 needs to be reduced accordingly under the same floor area, thereby reducing the flow velocity of the flue gas in the dust collection chamber 31. Therefore, the horizontal electrostatic precipitator 3 has a larger requirement for cross-sectional area.

[0041] In this embodiment, the top of the dust removal chamber 31 and the top of the preheater 2 are connected by a U-shaped pipe, which reduces the number of bends, makes the flue gas flow into the dust removal chamber 31 from the preheater 2 more smoothly, reduces system resistance, increases the flow velocity of flue gas in the dust removal chamber 31, and reduces the cross-sectional area requirement of the dust removal chamber 31, thus reducing the floor space occupied.

[0042] The connecting port 461 is located below the anode frame 33 and cathode frame 34 in the dust removal chamber 31, and below the rectifier layer 44 in the reaction chamber 41. The reaction chamber 41 is also provided with a flue gas outlet located above the catalyst layer 43.

[0043] Both the anode plate and the cathode wire are long strips. One end of the anode plate is fixedly connected and the other end is movably connected, and / or one end of the cathode wire is fixedly connected and the other end is movably connected.

[0044] Because both the anode plate and the cathode wire are elongated, they possess a degree of flexibility. Under the influence of airflow, the movable end of the anode plate will cause it to oscillate, and the movable end of the cathode wire will cause it to oscillate.

[0045] Specifically, the movable connection can be achieved by having a first slot on the anode frame, into which the lower end of the anode plate is inserted, and the volume of the first slot being larger than the volume of the lower end of the anode plate to provide space for the anode plate to swing. Similarly, a second slot on the cathode frame, into which the lower end of the cathode wire is inserted, and the volume of the second slot being larger than the volume of the lower end of the cathode wire to provide space for the cathode wire to swing.

[0046] Both the anode plates and cathode wires extend vertically, and multiple anode plates on the anode frame 33 and multiple cathode wires on the cathode frame 34 are arranged side-by-side at intervals. Flue gas entering the dust collection chamber 31 can pass through the gaps between the anode plates and the gaps between the cathode wires, prolonging the residence time of the flue gas in the dust collection chamber 31. This helps to increase the flue gas velocity at the cross-section entering the dust collection chamber, effectively reducing the volume of the dust collection chamber 31 and the floor space occupied by the electrostatic precipitator. In this embodiment, the multiple anode plates 33 and the multiple cathode wires 34 are all louvered.

[0047] The dust collection chamber 31 and the reaction chamber 41 are integrally connected, with a partition 46 between them. The partition 46 serves as a common sidewall between the two chambers, and a connection port 461 is located on the partition 46. Alternatively, it can be described as a partition 46 within a single integrated chamber, dividing the integrated chamber into the dust collection chamber 31 and the reaction chamber 41. This not only reduces the manufacturing materials required for the dust collection chamber 31 and the reaction chamber 41, but also further reduces the floor space required because the two chambers are integrated as a single unit without any gaps between them.

[0048] The integrated dust removal and denitrification device for cement kilns also includes a dust interceptor 5 located at the connection port 461. The dust interceptor 5 performs mechanical dust removal, intercepting the flaky dust collected by the dust hopper 32, and preventing the dust from being carried into the denitrification reactor 4 by the flue gas.

[0049] After being precipitated by the electrostatic precipitator 3, the flue gas enters the denitrification reactor 4. The connecting port 461 is located on the side wall of the reaction chamber 41, near the inlet of the reaction ash hopper 42. The exhaust port is located at the top of the reaction chamber 41. Because the bottom opening of the reaction chamber 41 connects to the inlet of the reaction ash hopper 42, and the reaction ash hopper 42 is vertically connected to the reaction chamber 41, it makes it easier for vertically falling dust to be collected by the reaction ash hopper 42. Therefore, the connecting port 461 is located on the side wall of the reaction chamber 41 to make way for the bottom opening of the reaction chamber 41. After entering the reaction chamber 41 through the connecting port 461 on the side wall, the flue gas begins to rise, passing through the rectifier layer 44 for uniform flow field distribution and rectification, allowing the flue gas to uniformly and vertically rise through multiple catalyst layers 43 in sequence, and finally exiting upwards along the flow direction of the flue gas from the exhaust port at the top of the reaction chamber 41, resulting in smoother exhaust.

[0050] The denitrification reactor 4 also includes a guide vane 47, which is located inside the reaction chamber 41, below the rectifying layer 44, and near the connecting port 461. The guide vane 47 is inclined upwards from the end near the connecting port 461 to the end away from the connecting port 461. When the flue gas enters the reaction chamber 41 through the connecting port 461 on the side wall of the reaction chamber 41, the flue gas flows laterally. Under the action of the guide vane 47, the flow direction of the flue gas can be changed, causing the flue gas to turn and flow towards the rectifying layer above the connecting port 461. The guide vane 47 can prevent the flue gas from blowing up the dust collected in the reaction ash hopper 42 downwards, making the flue gas flow field from bottom to top in the reaction chamber 41 smoother.

[0051] Multiple guide vanes 47 are arranged at vertical intervals, with their tilt angles gradually decreasing from top to bottom. That is, the uppermost guide vane 47 has a larger tilt angle, and the lowermost guide vane 47 has a smaller tilt angle. The uppermost guide vane 47 is closer to the rectifier layer 44, and the lowermost guide vane 47 is farther from the rectifier layer 44. The side of the rectifier layer 44 closest to the flue gas inlet is defined as the near end, and the side farther from the flue gas inlet is defined as the far end. The larger tilt angle of the uppermost guide vane 47 guides the flue gas to the near end of the rectifier layer 44, while the smaller tilt angle of the lowermost guide vane 47 guides the flue gas to the far end of the rectifier layer 44. The guide vane 47 in the middle has a moderate tilt angle, guiding the flue gas to the middle of the rectifier layer 44, ensuring that the flue gas is evenly distributed throughout the rectifier layer 44, achieving a uniform flue gas distribution effect. The guide vane 47 can be arc-shaped or straight.

[0052] It should be noted that by using the guide vane 47 and the rectifier layer 44 to evenly distribute the flue gas flow field, it is possible to avoid the situation where excessive flue gas volume in certain areas causes dust to clog the catalyst.

[0053] The denitrification catalyst can be one or more of plate type, honeycomb type and corrugated plate type. In this embodiment, the denitrification catalyst is a honeycomb type denitrification catalyst.

[0054] The catalyst layer 43 also includes a support frame for supporting the denitrification catalyst. The support frame may be a mesh structure, allowing the flue gas to pass through the support frame and contact the denitrification catalyst.

[0055] In this embodiment, multiple sets of cleaning devices 45 are provided, each corresponding to one of the multi-layer catalyst layers 43. Each set of cleaning devices 45 is used to clean the bottom surface of the denitrification catalyst in each catalyst layer 43. The catalyst layers 43 and the rectifying layer 44 are both arranged along the cross-sectional direction of the reaction chamber 41, and each set of cleaning devices 45 includes multiple cleaning devices 45 extending laterally. In other embodiments, only one set of cleaning devices 45 may be provided, used to clean the bottom surface of the denitrification catalyst on the lowest catalyst layer 43.

[0056] The dust removal device 45 can be any type of dust removal device, such as sonic, shock wave, or rake type.

[0057] A dust removal device 45 is disposed adjacent to the catalyst layer 43 below. The dust removal device 45 can be a purge pipe, which uses compressed gas to clean the bottom surface of the denitrification catalyst. Furthermore, the purge pipe blows upwards, consistent with the flow direction of the flue gas, but the blowing force is greater than the flow force of the flue gas. Large dust particles blown down by the purge pipe will fall due to gravity and be collected in the ash hopper, while other fine dust particles will be carried upwards by the flue gas through the catalyst. The purge pipe provides the driving force for the fine dust particles to pass through the catalyst with the flue gas.

[0058] The dust removal device 45 can also be a brush, which uses the back-and-forth movement of the brush to clean the bottom surface of the denitrification catalyst. The bottom catalyst layer 43 is used for interception in conjunction with the dust removal device 45 to achieve a secondary dust removal effect.

[0059] The rectifier layer 44 can be made of rectifier grid or honeycomb wear-resistant bricks. When honeycomb wear-resistant bricks are used in the rectifier layer 44, their excellent wear resistance can reduce the degree of wear caused by powder. Furthermore, the small pores within the honeycomb wear-resistant bricks also allow them to intercept dust, blocking most of the dust at the bottom surface of the rectifier layer 44. The dust removal device 45 is also used to clean the bottom surface of the rectifier layer 44, reducing the amount of dust entering the subsequent catalyst layer 43 and ensuring the stability and reliability of the denitrification reactor 4.

[0060] It should be noted that most existing SCR denitrification reactors are designed with top-in, bottom-out flue gas, and the few with bottom-in, top-out designs are only used in clean or low-dust environments. Conventional SCR reactors are arranged from top to bottom. Due to the small pore size of the catalyst within an SCR reactor, dust easily adheres to the catalyst surface, causing blockage. This not only affects the SCR reaction but also increases resistance. To solve the catalyst blockage problem, one approach is to install various soot blowing devices such as acoustic waves, shock waves, and rakes within the SCR denitrification reactor to blow away dust from the catalyst surface and carry it away with the flue gas. Another approach is to increase the catalyst pitch to reduce blockage. However, these methods are not suitable for applications with dust concentrations as high as 60 g / Nm³. 3 In the above situations, the above measures are insufficient to ensure that the catalyst does not become clogged. Once the catalyst becomes clogged, the overall denitrification efficiency will decrease, the system resistance will increase significantly, and eventually the system will have to be shut down for manual cleaning, which will affect the stability and reliability of the SCR denitrification system.

[0061] The integrated dust removal and denitrification device for cement kilns also includes an ash discharger 6. The ash discharger 6 is used to receive the dust discharged from the bottom outlet of the dust removal hopper 32 and the dust discharged from the bottom outlet of the reaction hopper 42, and discharge the dust to the raw material silo for dust recycling, thereby reducing the production cost of cement and preventing excessive ash accumulation in the dust removal hopper 32 and the reaction hopper 42.

[0062] The reaction chamber 41 is connected to the waste heat boiler 7 via the outlet flue 40, and the waste heat boiler 7 extends vertically. The flue gas outlet of the reaction chamber 41 is located at the top of the reaction chamber 41 and connects to the top of the waste heat boiler 7, while the bottom of the waste heat boiler 7 connects to the raw material grinding equipment. The denitrified flue gas is drawn to the waste heat boiler 7 for waste heat recovery, and then transported to the raw material grinding equipment for subsequent heat exchange.

[0063] The blower 8 is located on the flue between the waste heat boiler 7 and the raw material grinding equipment. It is used to drive the flow of flue gas in the flue and provides driving force for the flow of flue gas during the operation of the device.

[0064] The following is a specific embodiment of the integrated dust removal and denitrification device for cement kilns provided by the present invention.

[0065] Taking a 5000t / d cement kiln as an example, the flue gas temperature discharged from the C1 preheater 2 of the cement production line is around 260-350℃, and the dust concentration reaches 80-120g / Nm3. This flue gas enters the integrated dust removal and denitrification device from top to bottom through the inlet flue, first entering the electrostatic precipitator 3, where the flue gas velocity reaches as high as 3.5m / s. Simultaneously, an ammonia injection device is installed on the inlet flue. Based on the original NOx concentration value, ammonia water is atomized by compressed air and sprayed into the flue to evaporate and mix with the flue gas. After the flue gas enters the electrostatic precipitator 3, under the electrostatic action of the electric field between the anode and cathode frames, the dust becomes charged. Cation-carrying dust is adsorbed by the cathode wire, and anion-carrying dust is adsorbed by the anode plate. Since both the anode plate and cathode wire can be oscillating within the dust collection chamber, as the flue gas flows, the anode plate and cathode wire oscillate under the action of the airflow, shaking the dust on the anode plate and cathode wire into the dust collection hopper 32. To prevent secondary dust generation, a dust interceptor 5 is installed at the lower connection port 461 of the electrostatic precipitator 3. This interceptor 5 performs mechanical dust removal, intercepting the flaky dust collected in the dust hopper 32. The electrostatic precipitator 3 achieves a dust removal efficiency of up to 65%, reducing the dust concentration entering the denitrification reactor 4 to 28–42 g / Nm³, a significant reduction.

[0066] After being precipitated by the electrostatic precipitator 3, the flue gas enters the adjacent denitrification reactor 4 from bottom to top. The inlet of the denitrification reactor 4 is equipped with guide vanes 47 for guiding the flue gas flow. A rectifier layer 44 is also provided to ensure uniform distribution of the flue gas after passing through the catalyst layer 43, achieving flue gas homogenization. After the rectified, uniform flue gas comes into contact with the denitrification catalyst in the bottom catalyst layer 43. Due to the honeycomb porous structure of the denitrification catalyst, dust is further intercepted and adheres to the lower surface of the catalyst. When a certain level of dust accumulates, it can be blown down by a dust removal device 45 located at the bottom of the catalyst layer 43, falling into the reaction ash hopper 42. This achieves secondary dust removal of the flue gas, resulting in a dust removal efficiency of 40%, at which point 80% of the dust in the flue gas has been removed. The flue gas dust concentration is significantly reduced, effectively preventing clogging of the denitrification catalyst and ensuring that the flue gas entering the denitrification catalyst can effectively convert NOx in the flue gas into harmless nitrogen and water through catalytic action. The denitrified flue gas is then fed to the waste heat boiler 7 for waste heat recovery, and then sent to the raw material mill equipment via fan 8 for further heat exchange. The dust collected by the dust collector hopper 32 and the reaction ash hopper 42 is transported back to the raw material silo via the ash discharge machine 6.

[0067] Although the invention has been described with reference to several typical embodiments, it should be understood that the terminology used is illustrative and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An integrated dust removal and denitrification device for cement kilns, connected to the preheater of a cement production line via an inlet flue, wherein an ammonia injection device is installed on the inlet flue, characterized in that, include: An electrostatic precipitator includes a dust collection chamber, a dust collection hopper, an anode frame equipped with a swingable anode plate, and a cathode frame equipped with a swingable cathode wire. The dust collection chamber extends vertically, and the top of the dust collection chamber is connected to the inlet flue. The dust collection hopper is connected to the bottom of the dust collection chamber and communicates with the dust collection chamber. Multiple anode frames and multiple cathode frames are arranged alternately at equal intervals within the dust collection chamber. A denitrification reactor includes a reaction chamber, a reaction ash hopper, a catalyst layer, a rectifying layer, and a dust removal device. The reaction chamber extends vertically, and the reaction ash hopper is connected to the bottom of the reaction chamber and communicates with it. The catalyst layer is disposed within the reaction chamber and includes a denitrification catalyst. The catalyst layer has multiple layers spaced vertically. The rectifying layer is disposed within the reaction chamber and below the catalyst layer. The rectifying layer has multiple vertically extending rectifying holes evenly distributed on it. The dust removal device is disposed within the reaction chamber and is used to clean the bottom surface of the denitrification catalyst. The dust removal chamber and the reaction chamber are arranged adjacent to each other and are connected by a connecting port. The flue gas in the dust removal chamber flows from top to bottom and enters the reaction chamber through the connecting port. The flue gas in the reaction chamber flows from bottom to top.

2. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, The dust removal chamber and the reaction chamber are integrally connected; A partition is provided between the dust removal chamber and the reaction chamber, and the partition serves as a common side wall between the dust removal chamber and the reaction chamber. The communication port is located on the partition.

3. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, The connection port is located below the anode frame and the cathode frame in the dust removal chamber, and below the rectifier layer in the reaction chamber. The reaction chamber is also provided with a flue gas outlet located above the catalyst layer.

4. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, Both the anode plate and the cathode wire extend vertically; The anode plate and the cathode wire are arranged side by side at intervals.

5. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, The denitrification reactor also includes flow guide vanes; The flow guide plate is disposed inside the reaction chamber, below the rectifier layer, and near the communication port; The guide vane is inclined upwards from the end closest to the communication port to the end furthest from the communication port; The guide vanes are arranged in multiple vertically spaced intervals, and the tilt angle of the guide vanes gradually decreases from top to bottom.

6. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, The integrated dust removal and denitrification device for cement kilns also includes a dust interceptor located at the connection port.

7. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, The integrated dust removal and denitrification device for cement kilns also includes an ash discharge machine; The dust discharge machine is used to receive the dust discharged from the bottom outlet of the dust removal hopper and the dust discharged from the bottom outlet of the reaction hopper, and discharge the dust to the raw material silo.

8. The integrated dust removal and denitrification device for cement kilns according to claim 1, characterized in that, The reaction chamber is connected to the waste heat boiler via an outlet flue.

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