A high-temperature tunnel kiln for continuous sintering

Abstract

This invention discloses a continuous high-temperature tunnel kiln for sintering, comprising a kiln body with a channel and a travel track within the channel for kiln cars to travel in a straight line. A preheating zone, a sintering zone, and a cooling zone are sequentially formed within the channel along the direction of kiln car travel. A heating pipe is provided at the lower outer side of the kiln body corresponding to the sintering zone, and a cooling pipe is provided at the lower outer side of the kiln body corresponding to the cooling zone. A high-temperature exhaust gas pipe is also provided at the top of the kiln body. The inlet end of the high-temperature exhaust gas pipe is connected to the cooling zone, and the exhaust end is connected to a purification pipeline and the preheating zone via an electrically controlled three-way valve. A filter assembly with a self-cleaning function is also provided inside the inlet end of the high-temperature exhaust gas pipe. This high-temperature tunnel kiln enables continuous sintering of billets through the channels and zones within the kiln body; the high-temperature exhaust gas pipe allows heated exhaust gas to be introduced into the preheating zone for waste heat recovery, and the filter assembly and self-cleaning function ensure smooth flow of exhaust gas.

Description

Technical Field

[0001] This invention relates to the field of high-temperature tunnel kiln technology, specifically a high-temperature tunnel kiln for continuous sintering. Background Technology

[0002] The continuous high-temperature tunnel kiln for sintering is a core thermal equipment in the production process of inorganic non-metallic materials such as refractory materials, ceramics, and electronic components. Its interior is divided into a preheating zone, a sintering zone, and a cooling zone along the material conveying direction. The material is continuously carried through each temperature zone by the kiln car to realize the drying, preheating, sintering, and cooling processes of the material. In order to ensure product quality, the tunnel kiln usually adopts a stepped heating system, so that the billet is slowly heated in the preheating zone, treated at high temperature in the sintering zone, and gradually cooled in the cooling zone to prevent cracking defects caused by thermal stress.

[0003] To reduce energy consumption in production, existing tunnel kilns typically incorporate waste gas recovery systems. These systems guide high-temperature waste gas from the sintering or cooling zones back to the preheating zone via recovery pipes, utilizing the residual heat to preheat the incoming billets, thereby reducing energy consumption in the preheating zone. This waste heat recovery technology is of great significance for reducing production costs and improving energy efficiency.

[0004] However, the exhaust gas in the cooling zone carries a large amount of dust particles, which can lead to blockages in the recovery pipes and valves over long-term operation, affecting the exhaust gas flow and heat recovery efficiency, and in severe cases, even requiring shutdown for cleaning. To solve this problem, various self-cleaning filtration devices have emerged in existing technologies. For example, bag filters combined with pulse jet cleaning technology are used to filter and clean the flue gas, but the temperature resistance of the bag material is limited, making it only suitable for low-temperature flue gas dust removal. Metal mesh filters are also used to filter high-temperature exhaust gas, combined with a mechanical scraping mechanism for self-cleaning of the filter surface. However, mechanical scraping can only remove the filter cake from the filter surface, but cannot remove the scraped impurities from the filtration area. Impurities still accumulate near the filter, requiring manual cleaning after long-term operation, making true continuous production difficult.

[0005] Furthermore, the self-cleaning mechanism causes instantaneous and drastic fluctuations in airflow during operation, which in turn interferes with the temperature stability of the preheating zone, leading to temperature fluctuations inside the kiln and affecting the sintering quality of the billet. Summary of the Invention

[0006] Therefore, to address the aforementioned shortcomings, this invention provides a continuous high-temperature tunnel kiln for sintering. This high-temperature tunnel kiln enables continuous sintering of billets through channels and zones within the kiln body. Heated waste gas can be introduced into the preheating zone via a high-temperature waste gas pipeline to recover waste heat. A filter assembly and self-cleaning function ensure smooth flow of the waste gas. Simultaneously, an electrically controlled three-way valve activates during the self-cleaning of the filter assembly, effectively diverting instantaneous changes in airflow to maintain a stable flow rate into the preheating zone. This prevents excessive temperature fluctuations in the preheating zone from affecting the staged heating of the billets, thereby ensuring the sintering quality of the billets.

[0007] The present invention is achieved by constructing a continuous high-temperature tunnel kiln for sintering, including a kiln body, having a channel and a travel track provided in the channel for the kiln car to travel in a straight line. The passage is formed sequentially along the direction of the kiln car's travel, with a preheating zone, a sintering zone, and a cooling zone. Heating pipes and cooling pipes are provided at the lower outer ends of the kiln body corresponding to the sintering zone and the cooling zone. A high-temperature exhaust gas pipe is also provided at the top of the kiln body. The inlet end of the high-temperature exhaust gas pipe is connected to the cooling zone, and the exhaust end is connected to the purification pipeline and the preheating zone through an electrically controlled three-way valve. A self-cleaning filter assembly is also provided inside the inlet end of the high-temperature exhaust gas pipe.

[0008] Preferably, the kiln body is also provided with a cover and a protective door that keeps it raised and lowered at both ends of the channel. When the protective door is raised, it retracts into the cover to open the channel.

[0009] Preferably, one end of the high-temperature exhaust gas pipe is bent downwards and connected to the top of the kiln cooling zone to form an air inlet, and the other end is an exhaust end connected to one end of an electrically controlled three-way valve. The other two ends of the electrically controlled three-way valve are respectively connected to the purification pipeline and the preheating zone. The filter assembly is connected to the connection between the high-temperature exhaust gas pipe and the top of the kiln cooling zone. An induced draft fan is also installed in the air inlet of the high-temperature exhaust gas pipe to guide the airflow into the high-temperature exhaust gas pipe.

[0010] Preferably, the filter assembly includes a conical filter screen and a mounting component. The mounting component is annular and has a flange hole that maintains a flange connection with the end of the high-temperature exhaust gas pipeline and the top of the kiln cooling zone. The conical filter screen is placed on the mounting component through the folded edge of its large end, and the small end of the conical filter screen passes through the inner end of the mounting component and points towards the kiln cooling zone.

[0011] Preferably, a boss is provided on the outer end of the mounting component, and a slag discharge channel is provided inside the boss. One end of the slag discharge channel extends to the inner wall of the mounting component, and the other end is vertically downward connected to the external slag discharge pipe. A first driving component is provided on the outer end of the boss. The driving end of the first driving component is inserted into the slag discharge channel and moves linearly along the slag discharge channel to connect or block the slag discharge channel with the slag discharge pipe.

[0012] Preferably, the small end of the conical filter screen has a central hole, and a cleaning component is rotatably installed in the central hole. One end of the cleaning component has a scraper that contacts the outer conical surface of the conical filter screen, and the other end of the cleaning component passes through the conical filter screen and the second driving component at the outer end of the bend of the high-temperature exhaust gas pipe to maintain a transmission connection.

[0013] Preferably, a pressure sensor is installed in the inlet end of the high-temperature exhaust gas pipeline to detect the pressure difference Δ before and after the filter assembly. P When Δ P Reaching the preset cleanup initiation threshold P 1 At that time, the control system controls the first driving component to open the slag discharge channel and controls the second driving component to drive the cleaning component to rotate to clean the conical filter screen. When Δ P Reduce to the preset cleanup stop threshold P 2 At that time, the control system controls the second drive component to stop and controls the first drive component to close the slag discharge channel.

[0014] Preferably, the cleanup initiation threshold P 1 It is determined in the following way. , In the above formula, P 0 The normal pressure difference under clean conditions, Δ P 1 The maximum allowable differential pressure increment; The cleanup stop threshold P 2 It is determined in the following way. , In the above formula, Δ P 2 This is the preset hysteresis value.

[0015] Preferably, a temperature sensor is installed at the top of the preheating zone of the kiln body, and a speed sensor is installed on the traveling track to detect the traveling speed of the kiln car. The control system is electrically connected to the temperature sensor and the speed sensor, and the system operates based on the traveling speed of the kiln car detected by the speed sensor. v(t) Generate feedforward compensation amount α1 Based on the actual temperature detected by the temperature sensor T With set temperature T 0 deviation e(t) Establish a predictive model and generate feedback adjustment quantities. α 2 The feedforward compensation amount α 1 and feedback adjustment amount α 2 Generate the final opening control signal for the electrically controlled three-way valve. α(t) = α 1 + α 2 .

[0016] Preferably, the feedforward compensation amount α 1 It is determined in the following way. , In the above formula, K 1 This is the feedforward gain coefficient. α 0 The preset basic opening; The prediction model predicts future temperature deviations based on current and historical temperature deviations and valve openings. N Temperature deviation value at each sampling time e 1 , e 2 , ..., e N ,in e i For the future i The predicted value at each time point is used to calculate the feedback adjustment amount according to the following formula. α 2 , , In the above formula, N To predict the length of the time domain; w i The weighting coefficients are preset and satisfy the following conditions: , γ (Δ P The pressure difference Δ across the filter assembly is used as a reference. P A determined correction factor, when Δ P Below the first preset threshold P 1 hour, γ (ΔP )=1; when Δ P Reaching the second preset threshold P 2 hour, γ (Δ P )=0; when Δ P Between P 1 and P 2 When γ(Δ) P ) with Δ P It increases and then decreases monotonically.

[0017] Compared with the prior art, the present invention has the following advantages: First, the present invention enables the filtration and recycling of high-temperature waste gas by installing a filter component and a self-cleaning function in the high-temperature waste gas pipeline of the tunnel kiln. The filtered high-temperature waste gas can flow to the preheating zone to preheat the billet in the zone, forming a stepped heating of the billet and effectively utilizing waste resources.

[0018] Secondly, by setting the filter assembly as a conical filter screen, combined with the installation components, first drive component, second drive component, cleaning component, and slag discharge pipe, integrated continuous operation of filtration and slag discharge is achieved. The small end of the conical filter screen points towards the cooling zone, causing dust carried by the airflow to impact and adhere to the outer conical surface of the filter screen. The cleaning component rotates under the drive of the second drive component, scraping the impurities on the surface of the filter screen through a scraper. The scraped impurities fall into the slag discharge channel through the inner wall of the installation component and are discharged through the slag discharge pipe when the first drive component is opened. This structure solves the defect of existing metal filter screen self-cleaning mechanisms that cannot discharge scraped impurities, avoiding secondary blockage caused by impurities accumulating near the filter screen. Although a small amount of waste gas will be discharged from the slag discharge pipe during the cleaning process, it can carry away the impurities accumulated on the surface of the filter screen, eliminating the need for manual cleaning by stopping the machine. Only the waste gas discharged from the slag discharge pipe needs to be purified, thus achieving continuous and stable operation of the high-temperature tunnel kiln.

[0019] Secondly, a pressure sensor is installed at the inlet end of the high-temperature exhaust gas pipeline to monitor the pressure difference Δ across the filter assembly in real time. P And based on the preset startup threshold P 1 and stopping threshold P 2 Automatic control of the cleaning action, when Δ P achieve P 1 When Δ indicates that the filter cake on the filter screen surface is thick and needs cleaning, the control system activates the first drive component to open the slag discharge channel, and simultaneously activates the second drive component to drive the cleaning component to rotate and scrape off the ash; when Δ P Down to P 2When the filter screen is cleared, the control system stops the cleaning process and closes the slag discharge channel. This control mechanism ensures that the filter components are always in optimal working condition, guaranteeing both the flow of exhaust gas and reducing the load on the induced draft fan, thus ensuring the stable operation of the waste heat recovery system.

[0020] Finally, by installing temperature sensors in the preheating zone and speed sensors on the travel track, the kiln car's travel speed in the preheating zone can be monitored. v(t) Generate feedforward compensation amount α 1 The actual temperature detected by the temperature sensor T With set temperature T 0 deviation e(t) Feedback adjustment quantities are generated through predictive models. α 2 Generate the final opening control signal for the electrically controlled three-way valve. α(t) = α 1 + α 2 This control mechanism increases the exhaust gas return flow before the cold billet enters the preheating zone, effectively overcoming the temperature fluctuations caused by system lag, and avoiding the interference of airflow fluctuations caused by self-cleaning actions on the preheating zone temperature, thus achieving coordinated operation of the cleaning process and temperature control. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the detailed embodiments of the invention to explain the invention, but do not constitute any limitation on the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a structural schematic diagram of the present invention viewed from the front (the dashed lines and arrows in this figure indicate the direction of the kiln car's movement, and the text indicates the various areas). Figure 3 This is a schematic diagram of the structure of the present invention, which raises the protective door to allow the kiln car to enter the kiln body; Figure 4 This is a schematic diagram of the high-temperature exhaust gas pipeline and filter assembly of the present invention; Figure 5 for Figure 4 A schematic diagram of the structure viewed from the front; Figure 6 for Figure 5 Schematic diagram of the structure of section AA in the middle; Figure 7 This is a schematic diagram of the structure of the conical filter screen and mounting components of the present invention when disassembled; Figure 8This is a schematic diagram of the structure of the mounting component of the present invention; Figure 9 for Figure 8 A schematic diagram of the structure viewed from the front; Figure 10 for Figure 9 Schematic diagram of the structure of the middle BB section; Figure 11 This is a schematic diagram of the installation structure of the conical filter screen and cleaning component of the present invention; In the diagram: 1. Kiln body; 2. Cover; 3. Protective door; 4. Heating pipe; 5. Cooling pipe; 6. High-temperature exhaust gas pipe; 7. Purification pipe; 8. Electrically controlled three-way valve; 9. Exhaust fan; 10. Installation component; 11. Slag discharge pipe; 12. First drive component; 13. Second drive component; 14. Traveling track; 15. Kiln car; 16. Conical filter screen; 17. Cleaning component. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustrating and explaining the present invention and are not intended to limit the present invention in any way. The accompanying drawings in the present invention are only for describing the embodiments and for facilitating understanding and use, and are not intended to limit the present invention in any way.

[0023] It should be noted that the structures, proportions, sizes, etc. illustrated in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so that those skilled in the art can understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0024] As described in the background section, current high-temperature tunnel kilns used for sintering utilize waste gas recovery systems that can guide high-temperature waste gas from the sintering or cooling zones back to the preheating zone via recovery pipes. This waste heat is then used to preheat the incoming billets, reducing energy consumption in the preheating zone. However, the waste gas from the cooling zone carries a large amount of dust particles, which, with prolonged operation, can cause blockages in the recovery pipes and valves, affecting waste gas flow and heat recovery efficiency. In severe cases, shutdown for cleaning may be necessary. To address this issue, various self-cleaning filtration devices have emerged in the prior art. For example, bag filters combined with pulse jet cleaning technology are used to filter and clean the flue gas. However, the temperature resistance of the bag material is limited, making it only suitable for low-temperature flue gas dust removal. Metal mesh filters are also used to filter high-temperature waste gas, combined with a mechanical scraping mechanism for self-cleaning of the mesh surface. However, mechanical scraping only removes the filter cake from the mesh surface but cannot remove the scraped impurities from the filtration area. Impurities remain accumulated near the mesh, requiring manual cleaning after prolonged operation, making true continuous production difficult.

[0025] Furthermore, the self-cleaning mechanism causes instantaneous and drastic fluctuations in airflow during operation, which in turn interferes with the temperature stability of the preheating zone, leading to temperature fluctuations inside the kiln and affecting the sintering quality of the billet.

[0026] For the reasons stated above, please refer to the appendix for solutions to these problems. Figure 1 ~Appendix Figure 3 , The present invention provides a high-temperature tunnel kiln for continuous sintering, including a kiln body 1, wherein the kiln body 1 has a horizontally penetrating channel, and a travel track 14 for kiln cars 15 to travel in the channel.

[0027] The passage is divided into a preheating zone, a sintering zone and a cooling zone along the direction of travel of the kiln car 15. A heating pipe 4 is provided at the lower outer side of the kiln body 1 corresponding to the sintering zone to provide fuel combustion heating to the sintering zone; a cooling pipe 5 is provided at the lower outer side of the kiln body 1 corresponding to the cooling zone to introduce cooling medium to cool the sintered products. A high-temperature exhaust gas pipe 6 is also provided at the top of the kiln body 1. The inlet end of the high-temperature exhaust gas pipe 6 is connected to the cooling zone, and the exhaust end is connected to the purification pipe 7 and the preheating zone through an electrically controlled three-way valve 8. A self-cleaning filter assembly is also provided inside the inlet end of the high-temperature exhaust gas pipe 6.

[0028] Please refer to the appendix carefully. Figure 3 In order to reduce heat loss inside the kiln during sintering and concentrate heat inside the kiln to sinter the billet, in this embodiment, a cover 2 and a protective door 3 for raising and lowering are also provided at both ends of the channel of the kiln body 1. When the protective door 3 rises, it retracts into the cover 2 to open the channel.

[0029] Furthermore, to achieve automatic raising and lowering of the protective door, a lifting cylinder is installed inside the casing, which drives the protective door to rise and fall automatically.

[0030] Please see the appendix Figure 1 Appendix Figure 4 ~Appendix Figure 6 In this embodiment, one end of the high-temperature exhaust gas pipe 6 is bent downwards and connected to the top of the cooling zone of the kiln body 1 to form an air inlet, and the other end is an exhaust end and connected to one end of an electrically controlled three-way valve 8. The other two ends of the electrically controlled three-way valve 8 are respectively connected to the purification pipe 7 and the preheating zone. The filter assembly is connected to the connection between the high-temperature exhaust gas pipe 6 and the top of the cooling zone of the kiln body 1. An induced draft fan 9 is also provided in the air inlet of the high-temperature exhaust gas pipe 6 to guide the airflow into the high-temperature exhaust gas pipe 6. By adjusting the opening of the electrically controlled three-way valve 8, the proportion of exhaust gas flow back to the preheating zone can be controlled, and the remaining exhaust gas is discharged through the purification pipe 7.

[0031] Please refer to the appendix carefully. Figure 7 ~Appendix Figure 10 To facilitate the filtration of the exhaust gas flowing in the high-temperature exhaust gas pipeline and to block solid impurities mixed in the exhaust gas, preventing solid impurities from flowing back to the preheating zone and adhering to the billet, thus affecting the sintering quality, in this embodiment, the filter assembly includes a conical filter screen 16 and a mounting component 10. The mounting component 10 is annular and has a flange hole that connects to the end of the high-temperature exhaust gas pipeline 6 and the top of the cooling zone of the kiln body 1. The conical filter screen 16 is placed on the mounting component 10 through the folded edge of its large end, and the small end of the conical filter screen 16 passes through the inner end of the mounting component 10 and points towards the cooling zone of the kiln body 1.

[0032] Please refer to the appendix again. Figure 7 and attached Figure 10 To facilitate the discharge of solid impurities from the outer end of the filter screen and prevent solid impurities from accumulating on the outer end of the filter screen, thus eliminating the need for manual cleaning, in this embodiment, a boss is provided on the outer end of the mounting member 10. A slag discharge channel is provided inside the boss. One end of the slag discharge channel extends to the inner wall of the mounting member 10, and the other end is vertically downward connected to the external slag discharge pipe 11. A first driving member 12 is provided on the outer end of the boss. The driving end of the first driving member 10 is inserted into the slag discharge channel and moves linearly along the slag discharge channel to connect or block the slag discharge channel with the slag discharge pipe.

[0033] Furthermore, a dust collection box is provided below the outlet of the slag discharge pipe 11 to collect the scraped solid impurities. The dust collection box can be equipped with a sealing cover or a dust bag to prevent dust from flying during cleaning. At the same time, the exhaust port of the dust collection box is connected to the purification pipe 7, which can purify the small amount of waste gas discharged from the slag discharge pipe and prevent it from being directly discharged into the outside air.

[0034] Please refer to the appendix carefully.Figure 11 To facilitate effective cleaning of the conical filter screen and allow solid impurities at the outer end of the conical filter screen to flow into the slag discharge channel and be discharged, in this embodiment, a central hole is provided at the small end of the conical filter screen 16, and a cleaning component 17 is rotatably installed in the central hole. A scraper is provided on the outer side of one end of the cleaning component 17 to contact the outer conical surface of the conical filter screen 16, and the other end of the cleaning component 17 passes through the conical filter screen 16 and the second driving component 13 at the outer end of the bend of the inlet end of the high-temperature exhaust gas pipe 6 to maintain a transmission connection.

[0035] To facilitate self-cleaning of the filter assembly and prevent clogging caused by excessive impurities, in this embodiment, a pressure sensor is installed inside the inlet of the high-temperature exhaust gas pipe 6. The pressure sensor can be installed at both ends of the filter assembly to detect the pressure difference Δ across the filter assembly. P .

[0036] When Δ P Reaching the preset cleanup initiation threshold P 1 When the system determines that the filter cake on the filter screen surface is too thick and needs to be cleaned, the control system will perform the following actions: Control the first driving component 12 to move, the driving end retracts, and the slag discharge channel is opened, so that the inner wall of the mounting component 10 is connected to the slag discharge pipe 11. The second drive unit 13 is activated, driving the cleaning unit 17 to rotate. The scraper scrapes off the filter cake from the outer conical surface of the conical filter screen 16. The scraped-off impurities are pushed by the flow of exhaust gas, fall through the inner wall of the mounting part 10 into the slag discharge channel, and then are discharged out of the kiln through the slag discharge pipe 11. Δ is monitored during the cleaning process. P The changes.

[0037] When Δ P Reduce to the preset cleanup stop threshold P 2 When this occurs, it indicates that the filter has been restored to its normal flow, and the control system will perform the following actions: The second drive component 13 is stopped, and the cleaning component 17 stops rotating; After a delay of a period of time (e.g., 5 seconds) to ensure complete slag discharge, the first drive component 12 is controlled to extend, closing the slag discharge channel.

[0038] The above cleanup startup threshold P 1 It is determined in the following way. , In the above formula, P 0 The normal pressure difference under clean conditions (e.g., 50 Pa), Δ P 1 For the maximum allowable differential pressure increment (e.g., 150 Pa), thenP 1 =200Pa); The cleanup stop threshold P 2 It is determined in the following way. , In the above formula, Δ P 2 A preset hysteresis value (e.g., 10 Pa) is used to effectively prevent the cleaning mechanism from frequently starting and stopping near the threshold.

[0039] To facilitate airflow control in the preheating zone and ensure stable temperature within the zone, in this embodiment, a temperature sensor is installed at the top of the preheating zone of the kiln body 1, and a speed sensor is installed on the traveling track 14 to detect the kiln car's travel speed. The control system is electrically connected to the temperature sensor and the speed sensor, and operates based on the kiln car's travel speed detected by the speed sensor. v(t) Generate feedforward compensation amount α 1 The feedforward compensation amount α 1 It is determined in the following way. , In the above formula, K 1 The feedforward gain coefficient is obtained through step response experiments (e.g.) K 1 =0.05min / m), α 0 The preset base opening (e.g., 0.2) corresponds to the valve opening when the kiln is empty or at the lowest speed. This feedforward compensation can increase the exhaust gas flow rate in advance before the cold billet enters the preheating zone, effectively overcoming system lag.

[0040] Subsequently, based on the actual temperature detected by the temperature sensor T With set temperature T 0 Deviation (e.g., 200℃) e (t) , e(t) = T 0 - T Establish a predictive model and generate feedback adjustment quantities. α 2 , The prediction model predicts future temperature deviations based on current and historical temperature deviations and valve openings. N Temperature deviation value at each sampling time e 1 ,e 2 , ..., e N ,in e i For the future i The predicted value at each time point is used to calculate the feedback adjustment amount according to the following formula. α 2 , , In the above formula, N To predict the length of the time domain; w i The weighting coefficients are preset and satisfy the following conditions: , γ (Δ P The pressure difference Δ across the filter assembly is used as a reference. P A determined correction factor, when Δ P Below the first preset threshold P 1 hour, γ (Δ P )=1; when Δ P Reaching the second preset threshold P 2 hour, γ (Δ P When Δ = 0, the filter component's self-cleaning is triggered. Feedback adjustment is disabled at this time, and only feedforward compensation is retained to prevent airflow fluctuations caused by cleaning from interfering with temperature control; when Δ P Between P 1 and P 2 When γ(Δ) P ) with Δ P It increases and then decreases monotonically.

[0041] in P 2 Higher than P 1 This indicates that the filter is severely clogged and cleaning is about to be triggered.

[0042] According to the feedforward compensation amount α 1 and feedback adjustment amount α 2 Generate the final opening control signal for the electrically controlled three-way valve 8. α (t)， And it is limited to the range [0,1].

[0043] , Ultimately, this signal α(t)The output, after D / A conversion, is sent to the electric actuator of the electrically controlled three-way valve 8.

[0044] Sintering process: Set the target temperature of the preheating zone for the billet during sintering. T 0 =200℃, normal travel speed of kiln car v =1.5m / min. The filter is initially clean, Δ P =50Pa, γ =1. The control system operates stably, and the temperature in the preheating zone remains within the range of 200±2℃.

[0045] When the lifting cylinder drives the protective door 3 to rise, the internal travel track 14 of the kiln body 1 connects with the external track. At this time, the kiln car may travel faster (to avoid the protective door being open for a long time, causing smoke and dust to overflow or excessive heat loss). For example, the speed may increase to 3.0 m / min, and the feedforward compensation amount... α 1 To increase the value from 0.2 + 0.05 × 1.5 = 0.275 to 0.2 + 0.05 × 3 = 0.35, the valve should be opened more fully beforehand to avoid a temperature drop caused by the increased amount of cold billet. Simultaneously, the feedback adjustment should be fine-tuned based on the temperature deviation to ensure the temperature quickly returns to the set value.

[0046] When the kiln car is fully inside the kiln body 1 (e.g., by setting a photoelectric sensor at the bottom of the cover 2 to detect the position of the kiln car), the lifting cylinder drives the protective door 3 to descend, and the billet on the kiln car entering the kiln body is heated and sintered in a step-by-step manner. At this time, the speed of the kiln car may decrease, so the valve opening is reduced accordingly.

[0047] During the sintering process, the filter screen gradually becomes clogged, Δ P Rise to 150 Pa (still less than) P 1 =200Pa), γ The value remains 1, but the feedback adjustment calculation implicitly includes the effect of filter blockage—due to the reduced actual flow of exhaust gas entering the preheating zone, the temperature may show a downward trend, and the feedback adjustment will increase accordingly to compensate. When ΔP reaches 180Pa, γ begins to decrease linearly, and the feedback adjustment effect gradually weakens to prevent the controller from over-adjusting.

[0048] When Δ P When the pressure reaches 200Pa, the self-cleaning process is triggered: the first drive component 12 opens the slag discharge channel, and the second drive component 13 starts the rotation cleaning; simultaneously, γ =0, feedback adjustment amount α 2=0, the electrically controlled three-way valve 8 maintains its current opening α unchanged. During the cleaning process, although there may be momentary fluctuations in airflow, the valve will not swing accordingly because feedback is disabled, and the temperature fluctuation in the preheating zone is controlled within ±5℃. After about 30 seconds of cleaning, Δ P When the pressure drops to 60 Pa, the control system stops the cleaning components and closes the slag discharge channel. γ Reset to 1, feedback adjustment is re-enabled, and the system returns to normal control mode.

[0049] Through the above process, the tunnel kiln achieves automatic and continuous sintering of billets, as well as a self-cleaning process after filtration of high-temperature exhaust gas.

[0050] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A high-temperature tunnel kiln for continuous sintering, characterized in that: include, The kiln body has a passageway and a travel track is provided in the passageway for the kiln car to travel in a straight line; The passage is formed sequentially along the direction of the kiln car's travel, with a preheating zone, a sintering zone, and a cooling zone. Heating pipes and cooling pipes are provided at the lower outer ends of the kiln body corresponding to the sintering zone and the cooling zone. A high-temperature exhaust gas pipe is also provided at the top of the kiln body. The inlet end of the high-temperature exhaust gas pipe is connected to the cooling zone, and the exhaust end is connected to the purification pipeline and the preheating zone through an electrically controlled three-way valve. A self-cleaning filter assembly is also provided inside the inlet end of the high-temperature exhaust gas pipe.

2. The high-temperature tunnel kiln for continuous sintering according to claim 1, characterized in that: The kiln body is also equipped with a cover and a protective door that keeps it moving up and down at both ends of the channel. When the protective door is raised, it retracts into the cover to open the channel.

3. The high-temperature tunnel kiln for continuous sintering according to claim 1, characterized in that: One end of the high-temperature exhaust gas pipeline bends downwards and remains connected to the top of the kiln cooling zone to form an air inlet. The other end is the exhaust end and is connected to one end of an electrically controlled three-way valve. The other two ends of the electrically controlled three-way valve are respectively connected to the purification pipeline and the preheating zone. The filter assembly is connected to the connection between the high-temperature exhaust gas pipeline and the top of the kiln cooling zone. An induced draft fan is also installed in the air inlet end of the high-temperature exhaust gas pipeline to guide the airflow into the high-temperature exhaust gas pipeline.

4. The high-temperature tunnel kiln for continuous sintering according to claim 3, characterized in that: The filter assembly includes a conical filter screen and a mounting component. The mounting component is annular and has a flange hole that connects to the inlet end of the high-temperature exhaust gas pipeline and the top of the kiln cooling zone. The conical filter screen is placed on the mounting component with its large end folded over, and the small end of the conical filter screen passes through the inner end of the mounting component and points towards the kiln cooling zone.

5. The high-temperature tunnel kiln for continuous sintering according to claim 4, characterized in that: A boss is provided on the outer end of the mounting component. A slag discharge channel is provided inside the boss. One end of the slag discharge channel extends to the inner wall of the mounting component, and the other end is vertically downward connected to the external slag discharge pipe. A first driving component is provided on the outer end of the boss. The driving end of the first driving component is inserted into the slag discharge channel and moves linearly along the slag discharge channel to connect or block the slag discharge channel with the slag discharge pipe.

6. The high-temperature tunnel kiln for continuous sintering according to claim 5, characterized in that: The conical filter screen has a central hole at its small end, and a cleaning component is rotatably installed in the central hole. One end of the cleaning component has a scraper that contacts the outer conical surface of the conical filter screen. The other end of the cleaning component passes through the conical filter screen and the second drive component at the outer end of the bend of the high-temperature exhaust gas pipe to maintain a transmission connection.

7. The high-temperature tunnel kiln for continuous sintering according to claim 6, characterized in that: A pressure sensor is installed inside the inlet of the high-temperature exhaust gas pipeline to detect the pressure difference Δ before and after the filter assembly. P When Δ P Reaching the preset cleanup initiation threshold P 1 At that time, the control system controls the first driving component to open the slag discharge channel and controls the second driving component to drive the cleaning component to rotate to clean the conical filter screen. When Δ P Reduce to the preset cleanup stop threshold P 2 At that time, the control system controls the second drive component to stop and controls the first drive component to close the slag discharge channel.

8. The high-temperature tunnel kiln for continuous sintering according to claim 7, characterized in that: The cleanup start threshold P 1 It is determined in the following way. ， In the above formula, P 0 The normal pressure difference under clean conditions, Δ P 1 The maximum allowable differential pressure increment; The cleanup stop threshold P 2 It is determined in the following way. ， In the above formula, Δ P 2 This is the preset hysteresis value.

9. A high-temperature tunnel kiln for continuous sintering according to claim 7, characterized in that: A temperature sensor is installed at the top of the preheating zone of the kiln body, and a speed sensor is installed on the traveling track to detect the kiln car's traveling speed. The control system is electrically connected to the temperature sensor and the speed sensor, and operates based on the kiln car's traveling speed detected by the speed sensor. v(t) Generate feedforward compensation amount α 1 Based on the actual temperature detected by the temperature sensor T With set temperature T 0 deviation e(t) Establish a predictive model and generate feedback adjustment quantities. α 2 The feedforward compensation amount α 1 and feedback adjustment amount α 2 Generate the final opening control signal for the electrically controlled three-way valve. α(t) = α 1 + α 2 .

10. A high-temperature tunnel kiln for continuous sintering according to claim 9, characterized in that: The feedforward compensation amount α 1 It is determined in the following way. ， In the above formula, K 1 This is the feedforward gain coefficient. α 0 The preset basic opening; The prediction model predicts future temperature deviations based on current and historical temperature deviations and valve opening degrees. N Temperature deviation value at each sampling time e 1 , e 2 , ..., e N ,in e i For the future i The predicted value at each time point is used to calculate the feedback adjustment amount according to the following formula. α 2 , ， In the above formula, N To predict the length of the time domain; w i The weighting coefficients are preset and satisfy the following conditions: , γ (Δ P The pressure difference Δ across the filter assembly is used as a reference. P A determined correction factor, when Δ P Below the first preset threshold P 1 hour, γ (Δ P )=1; when Δ P Reaching the second preset threshold P 2 hour, γ (Δ P )=0; when Δ P Between P 1 and P 2 When γ(Δ) P ) with Δ P It increases and then decreases monotonically.

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