A lime kiln dust collection and processing device

Abstract

The application relates to the technical field of industrial kiln flue gas purification and resource recovery, in particular to a lime kiln dust collecting and processing device which is a multistage processing device comprising an impact wave buffer cavity, a vortex coagulation chamber, a dynamic gas-solid separation ring, a bag-type dust collector, a hot air back-blowing system, a back-dust system and a central cooperative controller. High-pressure dust-containing gas is depressurized through the buffer cavity, enters the vortex coagulation chamber, is coagulated by sound waves, and then is separated from dust through the dynamic separation ring made of shape memory alloy blades. The separated gas enters the bag-type dust collector for fine filtration, and the dust is cleaned by hot air back-blowing using the residual heat of the kiln body. The collected dust is reused to the finished product conveying belt after passivation and activation treatment. The application realizes step-by-step buffer of pressure relief impact and dust resource utilization, the emission concentration is lower than 5 mg / Nm3, the finished product activity retention rate is greater than or equal to 98%, and the energy consumption and secondary pollution are significantly reduced.

Description

Technical Field

[0001] This application relates to the field of industrial kiln flue gas purification and resource recovery technology, and in particular to a lime kiln dust collection and treatment device. Background Technology

[0002] During the reversal process of production in a parallel-flow regenerative double-chamber vertical lime kiln, the pressure inside the kiln is instantly released from a positive pressure state, generating a shock wave as high as 17-30 kPa, which carries a large amount of fine dust (particle size ≤10μm, accounting for more than 65%) out at high speed. Due to the excessively high initial shock wave pressure, traditional bag filters cannot be directly connected (the filter bags typically have a withstand limit of no more than 3 kPa), resulting in existing technologies mostly using empty exhaust or simple cyclone dust collection, leading to serious fugitive dust emissions and long-term exceedances of dust concentration in the plant environment.

[0003] Therefore, there is an urgent need for a device that can withstand pressure relief impacts, efficiently purify dust-laden gas, and realize the resource utilization of dust. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a lime kiln dust collection and treatment device.

[0005] This application provides a lime kiln dust collection and treatment device, which adopts the following technical solution: The device includes: The shock wave buffer chamber has its air inlet connected to the pressure relief valve of the lime kiln body through a pressure relief pipe. Inside, there is an impact-resistant and wear-resistant target plate facing the air inlet, which is used to absorb the shock wave energy at the initial moment of pressure relief.

[0006] The vortex coagulation chamber has an air inlet connected to the air outlet of the shock wave buffer cavity. Inside, there are double tangential air inlets to create a rotating and rising vortex field for the dust-laden gas. An acoustic generator is also embedded to promote the collision and coagulation of fine dust particles into large particles.

[0007] A dynamic gas-solid separation ring is located at the top outlet of the vortex condensation chamber. It includes a set of guide vanes arranged in a ring. The guide vanes are made of shape memory alloy. The vane angle is automatically deflected by the instantaneous temperature change of the depressurized gas to achieve gas-solid separation.

[0008] The bag filter dust collector has its inlet end connected to the outlet end of the dynamic gas-solid splitting ring via a pipe.

[0009] The hot air backflushing system has its air inlet connected to the waste heat recovery pipe of the lime kiln body and its air outlet connected to the clean air chamber of the bag filter. It is used to introduce hot air to backflush the filter bags during the pressure relief interval.

[0010] The ash return system is located below the vortex condensation chamber, the dynamic gas-solid splitting ring, and the bag filter. It includes a humidifier with a dual-chamber structure. The first chamber is a passivation chamber, which is connected to the kiln tail flue gas duct to introduce saturated steam containing carbon dioxide. The second chamber is an activation chamber, which is equipped with a binder injection inlet.

[0011] The central coordinating controller is connected to the reversing control system of the lime kiln body, the acoustic generator, the hot air backflushing system, and the ash return system, respectively, and is used to perform predictive feedforward control based on the predicted pressure relief sequence.

[0012] As a further improvement, the sound wave generator operates at a frequency of 80Hz-200Hz. Its frequency control module is connected to a pressure sensor located at the inlet of the shock wave buffer cavity. The central coordinating controller dynamically adjusts the sound wave frequency according to the real-time monitored shock wave pressure value: when the shock wave pressure is ≥15kPa, the frequency is adjusted to 80-100Hz to enhance the coagulation effect; when the shock wave pressure is <8kPa, the frequency is adjusted to 150-200Hz to reduce energy consumption.

[0013] As a further improvement, the guide vane angle adjustment range of the dynamic gas-solid splitting ring is 30° to 60°, and the phase transition temperature of the shape memory alloy is 180°-250°. When the temperature of the depressurized gas reaches above the phase transition temperature, the vane automatically deflects to the maximum angle of 60° to increase the centrifugal separation force. When the gas temperature drops below the phase transition temperature, the vane returns to the minimum angle of 30° to reduce system resistance.

[0014] As a further improvement, the bag filter uses a three-layer gradient filter material: the outer layer is a needle-punched felt layer resistant to 250℃ high temperature, the middle layer is an ultra-fine fiber layer for intercepting submicron dust, and the inner layer is an anti-static conductive fiber layer. The hot air temperature introduced by the hot air backflushing system is 120℃-150℃, and its control valve is connected to the central coordinating controller. It is only opened when the lime kiln body is in the reversing interval and the pressure difference between the inlet and outlet of the bag filter is higher than 1200Pa.

[0015] As a further improvement, in the dual-cavity humidification modifier, the passivation cavity is equipped with an array of atomizing nozzles for spraying saturated steam containing 5%-15% carbon dioxide by volume to form a thin layer of calcium carbonate on the surface of the recovered dust; the activation cavity is equipped with micro-nozzles for spraying in an organic binder accounting for 0.1%-0.3% of the dust mass; the organic binder is lignin sulfonate or sodium carboxymethyl cellulose.

[0016] As a further improvement, the central coordinating controller includes a pressure relief timing prediction module, which is directly connected to the reversing control system of the lime kiln body to obtain the pressure relief plan for the next 30 seconds. According to the pressure relief plan, the central coordinating controller starts the sound wave generator to the preparatory frequency 5-10 seconds before the pressure relief time arrives, and drives the dynamic gas-solid splitting ring to preheat to the working state. After the pressure relief is completed, it automatically switches to the energy-saving standby mode.

[0017] As a further improvement, an online laser particle size analyzer is installed at the outlet of the ash recovery system. The central coordinating controller dynamically adjusts the steam injection rate in the passivation chamber and the binder injection rate in the activation chamber based on the particle size distribution data fed back by the laser particle size analyzer, ensuring that the particle size matching degree between the recovered dust and the finished lime does not exceed ±5%.

[0018] The present invention also provides a method for collecting and treating dust from lime kilns using the above-mentioned device, comprising the following steps: S1: Impact buffering step. The high-pressure dust-laden gas generated by the depressurization of the lime kiln body enters the shock wave buffer cavity. The impact-resistant and wear-resistant target plate absorbs the peak pressure and reduces the shock wave pressure from 17-30kPa to below 8kPa. S2: Vortex coalescence step, gas enters the vortex coalescence chamber to form a rotating and rising vortex field. The central coordinating controller starts the sound wave generator in advance according to the predicted pressure relief sequence, which causes fine dust to collide and coalesce to form agglomerated particles with a particle size ≥20μm. S3: Dynamic flow separation step, gas flows through dynamic gas-solid flow separation ring, shape memory alloy blades automatically deflect the angle according to gas temperature, separate the agglomerated high-concentration dust and introduce it into the ash return system. S4: Fine filtration step. The gas enters the bag filter for purification. The central coordinating controller starts the hot air back-blowing system during the pressure relief interval and when the pressure difference is higher than 1200Pa. The waste heat is used to back-blow the filter bags to achieve dust removal. S5: Modification and reuse step. The dust collected by the ash recovery system enters the passivation chamber and activation chamber in sequence. After being passivated by carbon dioxide saturated steam and activated by organic binder, it is transported to the lime finished product conveyor belt for mixing and off-site transportation.

[0019] As a further improvement, in step S2, the frequency of the acoustic generator is dynamically adjusted based on real-time feedback from the pressure sensor at the inlet of the shock wave buffer cavity: 80-100Hz is used during the pressure peak stage, and 150-200Hz is used during the pressure attenuation stage.

[0020] In summary, this application includes the following beneficial technical effects: 1. Achieve ultra-low emissions: Through three-stage pre-purification of impact buffering, eddy coagulation and dynamic diversion, the dust concentration and particle size entering the bag filter are significantly reduced. With the help of three-layer gradient filter material, the outlet emission concentration can be stably controlled below 5mg / Nm³, which is far superior to the national emission standards.

[0021] 2. High resource utilization rate: After surface passivation and binder activation treatment, the recovered lime dust can be directly mixed into the finished lime conveyor belt, achieving 100% recycling and avoiding raw material waste.

[0022] 3. Protecting lime activity: The passivation chamber introduces saturated carbon dioxide vapor to form a thin layer of calcium carbonate on the dust surface, which effectively inhibits the hydration reaction (dissolution) that occurs after the recycled dust is mixed into the finished product. The activity retention rate of the finished product is ≥98%, which solves the technical problem of "recycled dust reducing the activity of the finished product" that has long existed in the industry.

[0023] 4. Significant energy saving and consumption reduction: The shape memory alloy blades automatically deflect by utilizing the temperature change of the depressurized gas itself, without the need for external power; the hot air backflushing system utilizes the waste heat of the kiln body to replace the traditional compressed air pulse cleaning, reducing overall energy consumption by about 30%.

[0024] 5. Intelligent Adaptive: The central coordinating controller is directly connected to the kiln reversing system to achieve predictive feedforward control. Each module automatically adjusts its operating parameters according to the depressurization sequence and real-time operating conditions, greatly improving the durability and adaptability of the equipment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the device; Figure 2 This is a schematic diagram of the dynamic gas-solid splitting ring of this device; Figure 3 This is a schematic diagram of the dual-cavity humidification modifier structure of this device; Figure 4 This is the control logic block diagram of this device; Figure 5 This is a schematic diagram showing the airflow and dust flow direction of this device; The components include: 1. Lime kiln body; 2. Shock wave buffer chamber; 3. Vortex coagulation chamber; 4. Dynamic gas-solid diversion ring; 5. Bag filter; 6. Hot air backflushing system; 7. Ash return system; 8. Central coordinating controller; 9. Lime finished product conveyor belt; 11. Pressure relief valve; 12. Pressure relief pipeline; 14. Reversing control system; 22. Impact-resistant and wear-resistant target plate; 24. Pressure sensor; 31a. Double tangential air inlet pipe; 31b. Double tangential air inlet pipe; 32. Acoustic wave generator; 42. Guide vane; 51. Clean air chamber; 54. Filter bag; 61. Waste heat recovery pipeline; 63. Control valve; 72. Dual-chamber humidifier and modifier; 73. Online laser particle size analyzer; 81. Pressure relief timing prediction module; 721. Passivation chamber; 722. Activation chamber; 721a. Atomizing nozzle array; 722a. Micro-nozzle. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that these embodiments are only for explaining the invention and do not constitute a limitation on the scope of protection of this invention. Example

[0027] Reference Figures 1 to 5 This embodiment provides a dust collection and treatment device for a parallel-flow regenerative double-chamber lime vertical kiln.

[0028] I. Overall Structure and Connections like Figure 1 As shown, the device includes: a shock wave buffer chamber 2, a vortex condensation chamber 3, a dynamic gas-solid diversion ring 4, a bag filter 5, a hot air backflushing system 6, a dust return system 7, and a central coordinating controller 8.

[0029] A pressure relief valve 11 is installed at the top of the lime kiln body 1. This pressure relief valve 11 is connected to the air inlet of the shock wave buffer chamber 2 via a pressure relief pipe 12. The air outlet of the shock wave buffer chamber 2 is connected to the air inlet of the vortex condensation chamber 3 via a pipe. A dynamic gas-solid splitting ring 4 is installed at the top outlet of the vortex condensation chamber 3. The air outlet of the dynamic gas-solid splitting ring 4 is connected to the air inlet of the bag filter 5 via a pipe. The clean air chamber 51 of the bag filter 5 is connected to the exhaust pipe 52.

[0030] The inlet of the hot air backflushing system 6 is connected to the waste heat recovery port 13 of the lime kiln body 1 via a waste heat recovery pipe 61, and the outlet is connected to the clean air chamber 51 of the bag filter 5 via a hot air pipe 62. The waste heat recovery port 13 is located in the cooling zone of the lime kiln body 1, and a coarse metal mesh filter (40 mesh) is installed before the recovery port to intercept large dust particles and ensure the cleanliness of the hot air entering the backflushing system.

[0031] The ash return system 7 is located below all ash hoppers: the bottom of the vortex condensation chamber 3 is equipped with a first ash hopper 31, the outer periphery of the dynamic gas-solid diversion ring 4 is equipped with a negative pressure suction port 41 (connected to the ash return system via a pipe), and the bottom of the bag filter 5 is equipped with a second ash hopper 53. The outlet of each ash hopper is connected to a screw conveyor 71, and the outlet of the screw conveyor 71 is connected to a dual-chamber humidification and modification device 72.

[0032] The central coordinating controller 8 is connected via signal cables to the reversing control system 14 of the lime kiln body 1, the pressure sensor 24 at the inlet of the shock wave buffer chamber 2, the acoustic generator 32 in the eddy coagulation chamber 3, the control valve 63 of the hot air backflushing system 6, the actuators of the dual-chamber humidification and modification device 72, and the online laser particle size analyzer 73.

[0033] II. Specific Structure and Function of Each Component (a) Shock wave buffer cavity 2 Reference Figure 1 The shock wave buffer chamber 2 is a rectangular steel shell with a wall thickness of 10mm, lined with wear-resistant ceramic sheets. A flexible expansion joint 21 is installed at its air inlet to absorb vibrations during pipeline thermal expansion and pressure relief impacts. An impact-resistant and wear-resistant target plate 22 is vertically installed inside the chamber, directly opposite the air inlet. The target plate 22 has a honeycomb alumina ceramic structure (20mm thick) to absorb the peak pressure (17-30kPa) at the initial pressure relief, preventing high-speed airflow from directly scouring the rear wall of the chamber. A dust discharge port 23 is located at the bottom of the chamber to discharge pre-settled large particles of dust. A pressure sensor 24 (range 0-40kPa, accuracy ±0.5%) is installed on the inlet pipe of the chamber to monitor the airflow pressure entering the device in real time.

[0034] (ii) Vortex Coagulation Chamber 3 Reference Figure 1 The vortex condensation chamber 3 is a cylindrical vertical cavity (1200mm in diameter and 1800mm in height), made of Q235B steel plate with a wear-resistant inner lining. Its air inlet is equipped with two tangential air inlet pipes 31a and 31b, which are arranged symmetrically at 180°, so that the incoming gas forms a rotating and rising vortex field, which prolongs the residence time of dust in the cavity (design residence time ≥1.5s).

[0035] A sound wave generator 32 is installed in the lower middle part of the cavity. This sound wave generator 32 is a diaphragm-type sound wave transducer driven by compressed air, with an operating frequency range of 80-200Hz and a sound pressure level ≥140dB. The frequency control module of the sound wave generator 32 is connected to the central coordinating controller 8 via a signal line, and simultaneously receives real-time pressure signals from the pressure sensor 24. The central coordinating controller 8 has a built-in PID algorithm that dynamically adjusts the sound wave frequency according to the pressure value: when the pressure is ≥15kPa, it outputs a low frequency of 80-100Hz, utilizing the strong penetrating power of low-frequency sound waves to cause the fine dust to vibrate and collide violently; when the pressure is <8kPa, it outputs a high frequency of 150-200Hz to reduce energy consumption. A first ash hopper 31 with a cone angle of 60° and lined with wear-resistant plates is located at the bottom of the cavity.

[0036] (III) Dynamic gas-solid splitting ring 4 like Figure 2 As shown, the dynamic gas-solid splitting ring 4 is installed at the top outlet of the vortex condensation chamber 3, and is an annular shell (outer diameter 800mm, inner diameter 500mm, height 200mm). Twelve guide vanes 42 are evenly arranged circumferentially inside the shell. The vanes are made of NiTi-based shape memory alloy (SMA), and the phase transition temperature Af is set at 200℃±10℃. Each vane has a mounting hole machined at its root and is fixedly connected to the flange of the rotating shaft 43 by high-temperature bolts. A 0.5mm gap is left between the vane and the shell to accommodate thermal expansion. A return torsion spring 44 is fitted on the rotating shaft 43 to assist the vanes in returning to a small angle at low temperatures.

[0037] The blade angle adjustment range is 30° to 60°. When the temperature of the depressurized gas is below 180° (such as in non-depressurization state or at the end of depressurization), the blade maintains a minimum angle of 30°, at which point the airflow resistance is minimal. When the temperature of the depressurized gas reaches above 200° (the high-temperature shock wave in the initial stage of depressurization), the shape memory alloy undergoes a martensitic inverse phase transformation, and the blade automatically deflects to a maximum angle of 60°. At this point, the flow channel cross-section decreases, the tangential velocity of the airflow increases, and the centrifugal separation effect reaches its maximum. An annular gap is formed between the outer periphery of the blade and the annular shell, which connects to the negative pressure suction port 41. The negative pressure suction port 41 is connected to the screw conveyor 71 of the ash return system through a pipe. The induced draft fan (not shown in the figure) of the ash return system generates a slight negative pressure (-500Pa to -1000Pa) to promptly remove the separated high-concentration dust. The central outlet of the diversion ring is a clean airflow channel, connected to the bag filter 5.

[0038] (iv) Baghouse dust collector 5 Reference Figure 1 The bag filter 5 is a box-type dust collector with external dimensions of 3000×2000×4500mm. It contains 120 filter bags 54, with a filter bag specification of Φ130×3000mm and a filtration area of ​​approximately 150m².

[0039] Filter bag 54 uses a three-layer gradient filter media: the outer layer is polyphenylene sulfide (PPS) needle-punched felt, temperature resistant up to 250℃, 1.5mm thick, with a pore size of approximately 30μm, mainly intercepting large dust particles and protecting the middle layer; the middle layer is a polytetrafluoroethylene (PTFE) ultrafine fiber layer, 0.3mm thick, with a pore size ≤5μm, mainly intercepting submicron dust; the inner layer is a conductive fiber layer blended with stainless steel fiber and PPS, with a surface resistivity ≤10 Ω·cm. 6 Ω is used to discharge static electricity and prevent spark discharge from the filter bag caused by static electricity buildup in dust. The three layers of filter media are bonded together using a hot-pressing composite process.

[0040] The upper part of the bag filter 5 is a clean air chamber 51, which has an outlet connected to an exhaust pipe 52. An induced draft fan (not shown in the figure) is installed in the exhaust pipe 52. A differential pressure sensor 55 is installed between the clean air chamber 51 and the dust-containing chamber to monitor the pressure difference before and after the filter bag in real time.

[0041] (v) Hot air backflushing system 6 The hot air backflushing system 6 includes: a waste heat recovery pipe 61 (leading out from the waste heat recovery port 13 of the lime kiln body 1, with an inner diameter of 150mm and an outer insulation layer), a hot air pipe 62 (connected to the clean air chamber 51), an electro-pneumatic butterfly valve 63 (as a control valve), and a temperature sensor 64 (installed on the hot air pipe 62).

[0042] Waste heat recovery port 13 is located in the cooling zone of the lime kiln body 1, where the flue gas temperature is stable at 200-300℃. To ensure the cleanliness of the hot air entering the bag filter, a coarse metal mesh filter (40 mesh) is installed before waste heat recovery port 13 to intercept particles larger than 0.5mm. The hot air is drawn out through an ejector (not shown in the figure) and transported to hot air duct 62 via a pipeline. Before the hot air reaches the clean air chamber 51, the temperature drops to 120-150℃ due to heat loss in the pipeline. Temperature sensor 64 monitors the hot air temperature; if the temperature is below 120℃, the control valve 63 is interlocked and an alarm is triggered.

[0043] The opening logic of control valve 63 is controlled by the central coordinating controller 8: the valve will only open when the following three conditions are met simultaneously: (1) the lime kiln body 1 is in the reversing interval (i.e. the pressure relief valve is closed and there is no pressure relief action, and the central coordinating controller 8 obtains the status signal from the reversing control system 14); (2) the differential pressure sensor 55 detects a pressure difference ≥ 1200 Pa; (3) the hot air temperature is in the range of 120-150℃. After the valve opens, the hot air enters the clean air chamber 51 in reverse and blows from the inside of the filter bag 54 outward. The dust layer on the surface of the filter bag is cracked and falls off due to the thermal expansion and contraction effect. The fallen dust falls into the second ash hopper 53. The backflushing duration is set to 10-15 seconds, after which the valve closes.

[0044] (vi) Ash return system 7 The ash return system 7 includes: a screw conveyor 71, a dual-chamber humidifier and modifier 72, and an online laser particle size analyzer 73.

[0045] The screw conveyor 71 is a horizontally arranged shaftless screw conveyor, 6m in length and 300mm in diameter, with a U-shaped trough shell lined with wear-resistant plates. The feed inlets of the screw conveyor 71 are connected to the first ash hopper 31 (bottom of the vortex condensation chamber), the negative pressure suction port 41 (outer circumference of the dynamic diversion ring), and the second ash hopper 53 (bottom of the bag filter). The discharge outlet of the screw conveyor 71 is connected to the feed inlet of the dual-chamber humidification and modification device 72.

[0046] like Figure 3 As shown, the dual-chamber humidifier 72 has a dual-tank horizontal series structure. Both tanks are cylindrical, with a diameter of 400mm and a length of 800mm. They are made of 304 stainless steel and have internal stirring blades.

[0047] First chamber (passivation chamber 721): The top of the chamber is equipped with an array of atomizing nozzles 721a (4 nozzles in a cross shape). The nozzles are connected to a steam generator and a carbon dioxide gas source (not shown in the figure) via pipes, forming saturated steam with a carbon dioxide volume concentration of 5%-15% after mixing. To accurately control the carbon dioxide concentration, an infrared carbon dioxide concentration analyzer (not shown in the figure) is installed on the mixing pipe, interlocked with the steam flow valve and the carbon dioxide flow valve, to adjust the mixing ratio in real time. The steam pressure is 0.2-0.4 MPa, and the injection volume accounts for 8%-12% of the dust mass. Inside the passivation chamber, the dust and the saturated carbon dioxide steam are in full contact. The active CaO on the dust surface reacts with CO2 to form a thin layer of CaCO3 (approximately 0.1-0.5 μm thick), thus "coating" the surface of the active lime and preventing violent hydration reaction (dissolution) with moisture after being mixed into the finished product. The bottom of the chamber is equipped with a discharge port, which connects to the second chamber.

[0048] The second chamber (activation chamber 722): A micro-nozzle 722a (high-pressure atomizing nozzle, 0.3mm orifice) is installed at the top of the chamber. The nozzle is connected to a binder storage tank and a metering pump (not shown in the figure) via a pipe. The binder is sodium lignosulfonate (a 30% solids content aqueous solution), and the injection volume is controlled at 0.1%-0.3% of the dry weight of the dust. The binder increases the adhesion between the recycled dust particles and the affinity with the finished lime particles, reducing secondary dust generation during transportation and mixing. A dual-shaft stirring paddle 722b (60-100 rpm) is installed inside the chamber to ensure uniform mixing of the binder and dust.

[0049] An online laser particle size analyzer 73 (model: MalvernInsitec, measurement range 0.1-1000μm) is installed at the outlet of the dual-chamber humidification modifier 72. The laser particle size analyzer 73 measures the particle size distribution of the modified dust in real time and sends the data to the central co-controller 8.

[0050] (vii) Central Coordination Controller 8 The central coordination controller 8 uses a Siemens S7-1500 series PLC and is equipped with a touch screen human-machine interface. Its core functions include: The pressure relief timing prediction module 81 is directly connected to the reversing control system 14 of the lime kiln body 1 via the Profinet bus. It reads the time parameters in the reversing program in real time to obtain whether pressure relief will occur within the next 30 seconds and the duration of the pressure relief. Based on this information, the controller issues a pre-start command 5-10 seconds before the pressure relief time arrives.

[0051] Sound wave generator frequency control: Receives the signal from pressure sensor 24, and outputs a 4-20mA analog signal through PID calculation to control the frequency converter of sound wave generator 32, thereby achieving continuous frequency adjustment.

[0052] Dynamic split ring preheating: 5-10 seconds before depressurization, the controller powers the electric heating strip (not shown in the figure, embedded installation, power 500W) in the housing of the dynamic gas-solid split ring 4 to preheat the split ring housing to about 150°C, ensuring that the SMA blades can quickly respond and deflect when the high-temperature gas arrives at the beginning of depressurization.

[0053] Hot air backflush control: Monitor the differential pressure sensor 55 and the reversing status of the lime kiln. When the conditions are met, output a digital signal to open the control valve 63 and start timing for 15 seconds before closing.

[0054] The ash return system operates in a closed-loop configuration, receiving particle size distribution data (D10, D50, D90) from the online laser particle size analyzer 73. The central coordinating controller 8 stores the target particle size curve of the finished lime (pre-input by the user). When the D50 deviation of the recovered dust exceeds the target value ±5%, the controller automatically adjusts the steam injection rate in the passivation chamber 721 and the binder injection rate in the activation chamber 722: if the dust is too fine, the binder injection rate is appropriately increased (up to 0.3%) to promote agglomeration; if the dust is too coarse, the binder injection rate is reduced (down to 0.1%) and the stirring speed is appropriately increased.

[0055] Energy-saving standby mode: When the lime kiln body is in stable operation for a long time (without pressure relief for more than 5 minutes), the controller will turn off the sound wave generator 32, cut off the power to the dynamic diversion ring preheating, keep the hot air back-blowing system in standby mode, and reduce the speed of the screw conveyor 71 and the dual-cavity humidifier 72 (minimum 30% of rated speed), which greatly reduces energy consumption.

[0056] III. Working Methods and Procedures The lime kiln dust collection and treatment method of this embodiment includes the following steps: Step S1: Shock buffer (see...) Figure 1 , Figure 5 ) The lime kiln body 1 reverses direction and releases pressure. Pressure relief valve 11 opens, allowing the generated high-pressure dust-laden gas (pressure 18-25 kPa, temperature 200-250℃, dust concentration 10-30 g / Nm³) to enter the shock wave buffer chamber 2 via pressure relief pipe 12. The airflow first impacts the impact-resistant and wear-resistant target plate 22; the peak pressure is absorbed by the target plate, and the pressure instantly drops to 8-10 kPa. Simultaneously, the flexible expansion joint 21 absorbs the impact vibration. The gas briefly resides in the buffer chamber (approximately 0.3 s), and some coarse particles larger than 100 μm settle due to gravity into the bottom ash discharge port 23 (to be manually cleaned periodically). Pressure sensor 24 records the inlet pressure value in real time and transmits it to the central coordinating controller 8.

[0057] Step S2: Eddy coagulation (see...) Figure 1 , Figure 4 , Figure 5 ) The buffered gas (pressure ≤ 8 kPa, temperature approximately 180-220℃) enters the vortex coagulation chamber 3. Due to the action of the dual tangential air inlets 31a and 31b, the gas forms a rotating and rising vortex field with a rotation speed of approximately 5-8 m / s. Based on the 30-second pressure relief plan obtained from the reversing control system 14, the central coordinating controller 8 activates the acoustic generator 32 8 seconds before the actual pressure relief occurs. When the pressure sensor 24 detects a pressure peak of 22 kPa, the controller sets the acoustic frequency to 85 Hz (within the 80-100 Hz range). The acoustic waves propagate within the vortex field, causing the fine dust particles with a diameter of 1-10 μm to vibrate and collide violently, forming agglomerated particles with a diameter of 20-50 μm. The coagulated gas flows out from the top outlet of the vortex coagulation chamber 3, and some of the agglomerated particles are thrown against the wall by centrifugal force and fall into the first ash hopper 31.

[0058] Step S3: Dynamic traffic splitting (see...) Figure 2 , Figure 5 ) The gas enters the dynamic gas-solid splitting ring 4. At this point, the gas temperature is approximately 200°C, reaching the phase transition temperature of the SMA blades. The blades automatically deflect from 30° to 60° within 3 seconds. The flow channel cross-section decreases, and the gas tangential velocity increases to 12-15 m / s, significantly improving centrifugal separation efficiency. The agglomerated high-concentration dust (particle size ≥ 20 μm) is thrown towards the outer periphery of the blades and sucked into the screw conveyor 71 of the ash return system through the negative pressure suction port 41. The purified gas (dust concentration reduced to 1-3 g / Nm³) flows out from the central outlet of the splitting ring and enters the bag filter 5.

[0059] Step S4: Fine filtration (see...) Figure 1 , Figure 4 , Figure 5 ) Gas enters the dust-laden chamber of the bag filter 5. As it passes through the filter bags 54, the remaining dust is intercepted by the three-layer gradient filter media. Clean gas enters the clean air chamber 51 and is discharged into the atmosphere via the exhaust pipe 52 and the induced draft fan. An online dust concentration monitor (not shown in the figure) is installed at the outlet of the exhaust pipe 52, showing that the emission concentration is stable at 3-5 mg / Nm³.

[0060] When the pressure difference across the filter bag 54 reaches 1200 Pa (detected by the differential pressure sensor 55), and the central coordinating controller 8 confirms that the lime kiln is currently in a reversing interval (without pressure relief), the controller opens the control valve 63, and hot air at 120-150℃ enters the clean air chamber 51 through the hot air duct 62, backflushing the filter bag for 15 seconds. The hot air causes the filter bag 54 to expand, and the dust layer cracks and falls off due to the difference in thermal expansion and contraction coefficients, falling into the second ash hopper 53. After the backflushing is completed, the pressure difference drops to 600-800 Pa.

[0061] Step S5: Modified Reuse (see...) Figure 3 , Figure 5 ) The dust collected by the first dust hopper 31, the negative pressure suction port 41, and the second dust hopper 53 (total amount of about 50-200 kg / h) is sent into the dual-chamber humidifier 72 via the screw conveyor 71.

[0062] First, the dust enters the passivation chamber 721: saturated steam (105°C) with a carbon dioxide concentration of 10% is injected into the atomizing nozzle array 721a, with the injection amount accounting for 10% of the dust mass. The dust and steam come into full contact under stirring, and the surface-active CaO reacts with CO2 to form a thin layer of CaCO3. The reaction equation is: CaO + CO2 → CaCO3. The surface activity of the treated dust is thus "passivated".

[0063] Then, the mixture enters the activation chamber 722: a sodium lignosulfonate solution (0.2% of the dry weight of the dust) is sprayed in by a micro-nozzle 722a, and the dual-shaft agitator 722b mixes it at 80 rpm for 2 minutes to ensure that the binder evenly coats the dust particles.

[0064] The online laser particle size analyzer 73 detected the particle size distribution of the modified dust: D10=8μm, D50=35μm, D90=120μm. The central coordinating controller 8 compared D50=35μm with the target D50=38μm of the finished lime, and the deviation was -7.9%, exceeding the ±5% threshold. The controller automatically increased the binder spray volume to 0.28% and simultaneously increased the stirring speed to 95rpm. After 5 minutes, the particle size distribution was measured again, and D50=37μm, with a deviation of -2.6%, which met the requirements.

[0065] The modified dust is transported through pipelines to the finished lime conveyor belt 9, where it is mixed with the finished lime produced in the kiln (temperature approximately 60-80℃) before being transported off-site. Because a CaCO3 passivation layer has formed on the surface of the dust, it will not undergo a hydration reaction with residual moisture in the finished lime or ambient humidity after mixing, thus ensuring the activity index of the finished lime (laboratory testing showed that the activity after mixing was ≥380mL, while the original finished product's activity was approximately 390mL, resulting in a retention rate of 97.4%).

[0066] IV. Control Logic Example To more clearly illustrate the operation of the central coordinating controller 8, the following description uses a typical pressure relief cycle as an example (see...). Figure 4 ).

[0067] After the lime kiln reversing control system 14 issues a pressure relief pre-signal, the central coordinating controller 8 begins predictive feedforward control. Specifically, 10 seconds before the pressure relief moment arrives, the controller first initiates a preheating program: the electric heating belt of the dynamic gas-solid splitting ring 4 is energized, and simultaneously, the acoustic generator 32 is activated to a preparatory frequency of 80Hz. Five seconds later (i.e., 5 seconds before pressure relief), the controller switches the acoustic frequency to 85Hz based on historical data and current operating conditions to match the upcoming pressure relief impact.

[0068] When the pressure relief valve 11 opens (T0), the pressure sensor 24 detects a pressure jump to 22 kPa. The controller confirms the frequency setting is correct, and simultaneously, the shape memory alloy blades of the dynamic gas-solid splitter ring 4 begin to deflect from 30° to 60°. One second after pressure relief, the pressure reaches its peak, and the sound wave frequency remains at 85 Hz. Three seconds later, the pressure drops to 12 kPa, and the controller adjusts the sound wave frequency to 120 Hz. Eight seconds later, the pressure further drops to 6 kPa, and the controller adjusts the sound wave frequency to 180 Hz, while the splitter ring blades begin to recover their angle. Twelve seconds later, the pressure relief valve closes, the controller shuts off the sound wave generator, the splitter ring heater is de-energized, and the pressure difference of the bag filter 5 is checked—the current pressure difference is 1050 Pa, which does not reach the 1200 Pa backflushing threshold, therefore hot air backflushing is not initiated. Fifteen seconds later, the system automatically enters energy-saving standby mode, waiting for the next pressure relief pre-signal.

[0069] Throughout the process, the central coordinating controller 8 obtains the pressure relief plan for the next 30 seconds of the reversing control system 14 in real time through the pressure relief timing prediction module 81, realizing precise feedforward control of the sound wave frequency, preheating timing, and backflushing logic, thus avoiding the lag and energy waste caused by passive response.

[0070] The working principle of this device has been explained through the above embodiments. These embodiments merely illustrate several implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A lime kiln dust collection and disposal apparatus, characterized by, include: The shock wave buffer cavity (2) has its air inlet connected to the pressure relief valve (11) of the lime kiln body (1) through the pressure relief pipe (12). Inside, there is an impact-resistant and wear-resistant target plate (22) facing the air inlet, which is used to absorb the shock wave energy at the initial moment of pressure relief. The vortex coagulation chamber (3) has an air inlet connected to the air outlet of the shock wave buffer chamber (2). It is equipped with double tangential air inlet pipes (31a, 31b) to make the dust-laden gas form a rotating and rising vortex field, and is also equipped with a sound wave generator (32) to promote the collision and coagulation of fine dust to form large particles. The dynamic gas-solid separation ring (4) is located at the top outlet of the vortex condensation chamber (3) and includes a set of guide vanes (42) arranged in a ring. The guide vanes (42) are made of shape memory alloy and the vane angle is automatically deflected by the instantaneous temperature change of the depressurized gas to achieve gas-solid separation. The bag filter (5) has its inlet end connected to the outlet end of the dynamic gas-solid splitting ring (4) via a pipe. The hot air backflushing system (6) has its air inlet end connected to the waste heat recovery pipe (61) of the lime kiln body (1) and its air outlet end connected to the clean air chamber (51) of the bag filter (5), which is used to introduce hot air backflushing the filter bag (54) during the pressure relief interval. The ash return system (7) is located below the vortex condensation chamber (3), the dynamic gas-solid splitting ring (4) and the bag filter (5), and includes a humidifier (72) with a dual-chamber structure. The first chamber is a passivation chamber (721), which is connected to the kiln tail flue gas pipe to introduce saturated steam containing carbon dioxide. The second chamber is an activation chamber (722), which is equipped with a binder spray inlet. The central coordinating controller (8) is connected to the reversing control system (14) of the lime kiln body (1), the acoustic generator (32), the hot air backflushing system (6) and the ash return system (7) respectively, and is used to perform predictive feedforward control according to the predicted pressure relief sequence.

2. A lime kiln dust collection and treatment apparatus according to claim 1, wherein, The sound wave generator (32) operates at a frequency of 80Hz-200Hz. Its frequency control module is connected to the pressure sensor (24) located at the inlet of the shock wave buffer cavity (2). The central coordinating controller (8) dynamically adjusts the sound wave frequency according to the real-time monitored shock wave pressure value: when the shock wave pressure is ≥15kPa, the frequency is adjusted to 80-100Hz; when the shock wave pressure is <8kPa, the frequency is adjusted to 150-200Hz.

3. A lime kiln dust collection and treatment apparatus as defined in claim 1, wherein, The angle adjustment range of the guide vanes (42) of the dynamic gas-solid splitting ring (4) is 30° to 60°, and the phase transformation temperature of the shape memory alloy is 180°-250°. When the temperature of the depressurized gas reaches above the phase transformation temperature, the vanes automatically deflect to the maximum angle of 60°. When the gas temperature drops below the phase transformation temperature, the vanes return to the minimum angle of 30°.

4. A lime kiln dust collection and treatment apparatus as defined in claim 1, wherein, The bag filter (5) uses a three-layer gradient filter material (54), the outer layer is a needle-punched felt layer that can withstand high temperatures of 250℃, the middle layer is an ultra-fine fiber layer that intercepts submicron dust, and the inner layer is an anti-static conductive fiber layer; the hot air temperature introduced by the hot air backflushing system (6) is 120℃-150℃, and its control valve (63) is connected to the central coordinating controller (8) by signal, and is only opened when the lime kiln body (1) is in the reversing interval and the pressure difference between the inlet and outlet of the bag filter (5) is higher than 1200Pa.

5. A lime kiln dust collection and disposal apparatus as defined in claim 1 wherein, In the dual-cavity humidifier (72), the passivation cavity (721) is equipped with an array of atomizing nozzles (721a) for spraying saturated steam containing 5%-15% carbon dioxide by volume to form a thin layer of calcium carbonate on the surface of the recovered dust; the activation cavity (722) is equipped with a micro-spray nozzle (722a) for spraying an organic binder accounting for 0.1%-0.3% of the dust mass; the organic binder is lignin sulfonate or sodium carboxymethyl cellulose.

6. A lime kiln dust collection and disposal apparatus as defined in claim 1 wherein, The central coordinating controller (8) includes a pressure relief timing prediction module (81), which is directly connected to the reversing control system (14) of the lime kiln body (1) to obtain the pressure relief plan within the next 30 seconds. According to the pressure relief plan, the central coordinating controller (8) starts the sound wave generator (32) to the preparatory frequency 5-10 seconds before the pressure relief time arrives, and drives the dynamic gas-solid splitting ring (4) to preheat to the working state. After the pressure relief is completed, it automatically switches to the energy-saving standby mode.

7. A lime kiln dust collection and disposal apparatus as defined in claim 1 wherein, The outlet of the ash recovery system (7) is equipped with an online laser particle size analyzer (73). The central coordinating controller (8) dynamically adjusts the steam injection amount of the passivation chamber (721) and the binder injection amount of the activation chamber (722) according to the particle size distribution data fed back by the laser particle size analyzer (73), so as to ensure that the particle size matching degree deviation between the recovered dust and the finished lime does not exceed ±5%.

8. A method for dust collection and disposal in a lime kiln using the apparatus of any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Impact buffering step, the high-pressure dust-laden gas generated by the depressurization of the lime kiln body (1) enters the shock wave buffer cavity (2), and the impact-resistant and wear-resistant target plate (22) absorbs the peak pressure, reducing the shock wave pressure from 17-30kPa to below 8kPa. S2: Vortex coagulation step, gas enters the vortex coagulation chamber (3) to form a rotating and rising vortex field, and the central coordinating controller (8) starts the sound wave generator (32) in advance according to the predicted pressure relief sequence, so as to cause fine dust to collide and coagulate to form agglomerated particles with a particle size ≥20μm; S3: Dynamic diversion step, gas flows through dynamic gas-solid diversion ring (4), shape memory alloy blades automatically deflect the angle according to gas temperature, separate the agglomerated high-concentration dust and introduce it into the ash return system (7). S4: Fine filtration step, the gas enters the bag filter (5) for purification, the central coordinating controller (8) starts the hot air back-blowing system (6) during the pressure relief interval and when the pressure difference is higher than 1200Pa, and uses the residual heat to back-blow the filter bag (54) to achieve dust removal; S5: Modification and reuse step, the dust collected by the ash return system (7) enters the passivation chamber (721) and activation chamber (722) in sequence. After being passivated by carbon dioxide saturated steam and activated by organic binder, it is transported to the lime finished product conveyor belt (9) for mixing and transportation.

9. The method of claim 8, wherein, In step S2, the frequency of the acoustic generator (32) is dynamically adjusted according to the real-time feedback from the pressure sensor (24) at the inlet of the shock wave buffer cavity (2): 80-100Hz is used during the pressure peak stage and 150-200Hz is used during the pressure attenuation stage.

10. A lime kiln dust collection and handling system characterized by, The system includes a lime kiln body (1) and a lime kiln dust collection and treatment device as described in any one of claims 1 to 7. The pressure relief valve (11) of the lime kiln body (1) is connected to the air inlet of the shock wave buffer cavity (2) through a pressure relief pipe (12). The waste heat recovery pipe (61) of the lime kiln body (1) is connected to the air inlet of the hot air backflushing system (6). The kiln tail flue gas pipe of the lime kiln body (1) is connected to the air inlet of the passivation cavity (721) in the ash return system (7). The central coordinating controller (8) is directly connected to the reversing control system (14) of the lime kiln body (1).

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