Anti-ringing suspension calcining furnace for kaolin suitable for high-speed railway and its control method

Abstract

This invention relates to an anti-ringing suspension calcination furnace for high-speed railway kaolin and its control method, belonging to the technical field of suspension calcination and anti-ringing control of high-speed railway kaolin. It includes: a furnace main frame vertically fixed on a base, with a main burner at the bottom center and a main swirl vent tangentially connected to a high-temperature flue gas generator at the bottom; an inner lining assembly within the frame, consisting of a cylindrical calcination chamber constructed of refractory bricks, longitudinally divided into independent annular sections with guide rings installed in the slits between sections; a secondary gas supply assembly, with an annular main pipe surrounding the outer wall of the frame connected to the annular cavity outside the inner lining via a branch pipe equipped with an adaptive negative pressure compensation valve; and a detection and control assembly, where an industrial control computer connects to a high-frequency pressure transmitter on the main pipe and a fast-response electromagnetic regulating valve, controlling their opening and closing. This invention reduces the probability of material adhesion to the furnace wall, achieving the anti-ringing function.

Description

Technical Field

[0001] This invention relates to the field of suspension calcination and anti-ringing control of kaolin for high-speed railways, specifically to an anti-ringing suspension calcination furnace and its control method applicable to kaolin for high-speed railways. Background Technology

[0002] Suspension calcination is a commonly used heat treatment process in the mineral processing field, and it has an important application in the processing of high-speed kaolin. Under normal working conditions, the material is suspended and undergoes phase transformation under the action of high temperature and strong centrifugal force. However, the high iron oxide content in high-speed kaolin is prone to forming low-melting-point eutectic with the silica-alumina matrix in the high-temperature phase transformation range. These semi-molten particles collide and adhere to the inner wall of the conventional single-layer furnace under the action of centrifugal force, thus causing the problem of ring formation and ash accumulation.

[0003] To address the problem of ash rings and buildup on furnace walls, external mechanical bombardment is a traditional method. While this method is direct, it often disrupts the continuous thermal regime and fails to prevent the initial adhesion of particles. Currently, to overcome the shortcomings of traditional physical ash removal methods, changing the conventional solid-wall contact mode has become the primary method for preventing ring formation. The main direction of improvement is to construct a dynamic fluid isolation barrier inside the furnace to achieve physical isolation between high-temperature suspended particles and the inner wall, eliminating the thermodynamic basis for the stickiness of semi-molten particles, thereby effectively inhibiting the initial deposition of eutectic materials on the refractory brick surface. Summary of the Invention

[0004] The purpose of this invention is to provide an anti-ringing suspension calcining furnace and its control method for high-speed railway kaolin, solving the following technical problems:

[0005] Existing suspension calcination technology often encounters the problem of ash accumulation and ring formation due to the adhesion of semi-molten particles to the furnace wall when processing high-speed kaolin. Traditional mechanical bombardment methods not only disrupt the thermal regime but also fail to prevent the initial adhesion behavior of particles. Therefore, there is an urgent need for a suspension calcination furnace and its control method that can change the solid-wall contact mode, construct a dynamic fluid isolation barrier, and combine pneumatic vibration to achieve active defense and removal of the deposit layer.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] The furnace body main frame is vertically fixed on the base. The main burner is located at the bottom center of the furnace body main frame. The main swirl air outlet is located on the lower side wall of the furnace body main frame along the tangential direction. The main swirl air outlet is connected to the high temperature flue gas generator.

[0008] The inner lining assembly is located inside the main frame of the furnace body. The inner lining assembly is constructed of refractory bricks and encloses a cylindrical calcination cavity. The inner lining assembly is divided into independent annular sections in the vertical direction, and annular slits are formed between adjacent annular sections. A guide ring is installed at the annular slit.

[0009] The secondary gas supply assembly includes an annular main pipe surrounding the outer wall of the main frame of the furnace body, wherein the annular main pipe is connected to the annular cavity outside the inner lining assembly through a branch pipe, and an adaptive negative pressure compensation valve is provided at the connection between the branch pipe and the annular cavity.

[0010] The detection and control assembly includes a high-frequency pressure transmitter and a fast-response solenoid valve mounted on the annular manifold. The high-frequency pressure transmitter and the fast-response solenoid valve are respectively connected to an industrial control computer, which controls the opening and closing of the fast-response solenoid valve.

[0011] As a further embodiment of the present invention, the guide ring is made of silicon carbide material, wherein the cross-sectional shape of the guide ring is wedge-shaped and has a wedge tip, the wedge tip points upward to the main frame of the furnace body and is in close contact with the inner wall of the lining assembly, and the guide ring guides the airflow passing through the annular slit to flow tangentially upward along the inner wall of the lining assembly to form a wall-adhering gas film.

[0012] As a further embodiment of the present invention, the adaptive negative pressure compensation valve includes a valve seat and an elastic diaphragm. The valve seat is fixed to the inlet flange of the annular cavity, and a vent hole is opened in the center of the valve seat. The edge of the elastic diaphragm is pressed against the valve seat. In its natural state, the elastic diaphragm covers the vent hole and leaves a preset gap. When the static pressure in the calcination chamber decreases, the elastic diaphragm deforms inward to increase the opening area of ​​the vent hole.

[0013] As a further embodiment of the present invention, the elastic diaphragm is made of high-temperature resistant fluororubber material, and the height of the annular slit is set to a preset slit height.

[0014] As a further embodiment of the present invention, the probe of the high-frequency pressure transmitter extends into the interior of the annular manifold, and the fast-response electromagnetic regulating valve is connected in series at the front end of the air inlet of the annular manifold, wherein the opening response time of the fast-response electromagnetic regulating valve is less than a preset response time threshold.

[0015] As a further embodiment of the present invention, the annular main pipe, the branch pipe and the annular cavity constitute a secondary airflow channel, and the airflow in the secondary airflow channel is modulated into a pulse flow by the fast-response electromagnetic regulating valve.

[0016] Control methods for anti-ringing suspension calcining furnaces of kaolin used in high-speed railways include:

[0017] S1. Under no-load conditions, the main swirl duct and the secondary gas supply assembly are started in the anti-ring suspension calcining furnace, and the first pressure pulsation data in the annular main pipe is collected by the high-frequency pressure transmitter.

[0018] S2. The industrial control computer performs spectrum analysis on the first pressure pulsation data to identify the fundamental frequency peak and its harmonic components, and establishes a flow field acoustic impedance reference model.

[0019] S3. During the material feeding and production process, the high-frequency pressure transmitter collects the second pressure pulsation data in the annular main pipe in real time, and the industrial control computer calculates and obtains the current power spectral density.

[0020] S4. The industrial control computer extracts low-frequency characteristic energy and high-frequency substrate energy based on the current power spectral density and calculates the fluid impedance distortion coefficient.

[0021] S5. The industrial control computer determines whether the fluid impedance distortion coefficient is greater than or equal to a preset threshold. If it is greater than or equal to the threshold, the industrial control computer sends a modulation signal to the fast-response electromagnetic regulating valve. If it is less than the threshold, the process returns to step S3.

[0022] As a further aspect of the present invention, step S5 includes:

[0023] S601. The fast-response electromagnetic regulating valve performs a high-frequency opening and closing action according to the modulation signal, converting the airflow entering the annular slit from a continuous flow to a pulsed flow;

[0024] S602. The pulse flow generates a periodic excitation force in the wall-adhering gas film on the inner wall surface of the lining assembly, wherein the excitation force acts perpendicularly on the furnace wall deposit layer.

[0025] As a further embodiment of the present invention, the modulation signal is a pulse width modulation signal, wherein the carrier frequency of the pulse width modulation signal is set to be out of phase with the turbulent main frequency of the main swirling flow field in the calcination cavity.

[0026] As a further aspect of the present invention, the method following step S5 includes:

[0027] S701. When the local flow channel cross-section in the calcination chamber narrows, causing a decrease in static pressure, the adaptive negative pressure compensation valve increases the opening degree by utilizing the pressure difference.

[0028] S702, The increased opening degree of the adaptive negative pressure compensation valve draws in a low-temperature pulse airflow to the ring-forming area for cooling and vibration stripping.

[0029] This invention provides an anti-ringing suspension calcining furnace and its control method for kaolin used in high-speed railways, which has the following improvements and advantages compared with the prior art:

[0030] 1. The present invention installs a guide ring at the annular slit formed between adjacent annular sections of the inner lining component. The guide ring has a wedge-shaped cross-section and is closely attached to the inner wall of the inner lining component. This effectively guides the airflow to flow tangentially upward along the inner wall of the inner lining component, thereby forming a wall-adhering air film. This air film can physically isolate the high-speed kaolin from the furnace wall, reduce the probability of material adhesion, and achieve the function of preventing ring formation.

[0031] 2. This invention utilizes a high-frequency pressure transmitter to collect pressure pulsation data in real time, and an industrial control computer calculates the fluid impedance distortion coefficient. When the coefficient is detected to reach or exceed a preset threshold, the system sends a modulation signal to the fast-response electromagnetic regulating valve, converting the airflow entering the annular slit from a continuous flow to a pulsed flow. This pulsed flow generates a periodic excitation force perpendicular to the furnace wall deposit layer in the wall-attached gas film, thereby actively breaking down and peeling off the attached ring material, improving the equipment's self-cleaning and continuous operation capabilities.

[0032] 3. The present invention is equipped with an adaptive negative pressure compensation valve. When the flow channel cross section narrows and the static pressure decreases due to local ring formation inside the calcination chamber, its elastic diaphragm will automatically deform inward, thereby increasing the opening area of ​​the vent. By utilizing the increased opening degree due to the pressure difference, a low-temperature pulse airflow can be automatically drawn into the ring formation area, and the local ring formation can be peeled off and removed through cooling and vibration. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly described below:

[0034] Figure 1 This is a schematic diagram of the overall external structure of the device;

[0035] Figure 2 This is a schematic diagram of the furnace body main frame and main burner structure of the device;

[0036] Figure 3 This is a schematic diagram of the internal structure of the main frame of the furnace body;

[0037] Figure 4 This is a schematic diagram of the adaptive negative pressure compensation valve structure of the device;

[0038] Figure 5 This is a schematic flowchart of a control method for an anti-ringing suspension calcining furnace for high-speed railway kaolin provided in an embodiment of this application.

[0039] In the diagram: 100, main furnace frame; 110, main burner; 120, main swirl nozzle; 130, base; 200, lining assembly; 210, calcination chamber; 220, annular section; 230, annular slit; 240, guide ring; 241, wedge tip; 250, annular cavity; 300, secondary gas supply assembly; 310, annular main pipe; 320, branch pipe; 330, adaptive negative pressure compensation valve; 331, valve seat; 332, vent; 333, elastic diaphragm; 334, preset gap; 335, counterweight; 400, detection and control assembly; 410, high-frequency pressure transmitter; 420, fast-response electromagnetic regulating valve. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0041] Example 1:

[0042] Please see Figure 1-4 Anti-ringing suspension calcining furnace for kaolin used in high-speed rail, including:

[0043] The furnace body main frame 100 is vertically fixed on the base 130. The main burner 110 is set at the bottom center of the furnace body main frame 100. The main swirl air inlet 120 is set along the tangential direction on the lower side wall of the furnace body main frame 100. The main swirl air inlet 120 is connected to the high temperature flue gas generator.

[0044] The inner lining assembly 200 is located inside the main frame 100 of the furnace body. The inner lining assembly 200 is constructed of refractory bricks and encloses a cylindrical calcination chamber 210. The inner lining assembly 200 is divided into independent annular sections 220 in the vertical direction. An annular slit 230 is formed between adjacent annular sections 220. A guide ring 240 is installed at the annular slit 230.

[0045] The secondary gas supply assembly 300 includes an annular main pipe 310 surrounding the outer wall of the furnace main frame 100. The annular main pipe 310 is connected to the annular cavity 250 outside the inner lining assembly 200 through a branch pipe 320. An adaptive negative pressure compensation valve 330 is provided at the connection between the branch pipe 320 and the annular cavity 250.

[0046] The detection and control component 400 includes a high-frequency pressure transmitter 410 and a fast-response solenoid regulating valve 420 mounted on the annular manifold 310. The high-frequency pressure transmitter 410 and the fast-response solenoid regulating valve 420 are respectively connected to an industrial control computer, and the industrial control computer controls the opening and closing of the fast-response solenoid regulating valve 420.

[0047] In the process of suspension calcination of high-speed railway kaolin, the high content of iron oxide in the raw material is very likely to form a low melting point eutectic with the silicon-aluminum matrix in the high temperature phase transformation range. These semi-molten particles collide with the inner wall of the furnace under the action of centrifugal force, which may cause the problem of ring formation and ash accumulation. Traditional external mechanical bombardment methods often interrupt the continuous thermal process and cannot block the initial adhesion behavior of particles.

[0048] To address the aforementioned technical obstacles, the furnace main frame 100 provided in this embodiment serves as a load-bearing structure, and together with the inner lining component 200 constructed of refractory bricks, it changes the traditional solid-wall contact mode; the inner lining component 200 is divided into independent annular sections 220 in the vertical direction and forms annular slits 230, which, together with the annular main pipe 310 and branch pipes 320 of the secondary gas supply component 300, construct a distributed channel for the introduction of external airflow.

[0049] The adaptive negative pressure compensation valve 330 configured at the connection between the branch pipe 320 and the annular cavity 250 can dynamically adjust the flow rate when the local flow field is distorted, in order to cope with the local ring protrusion; the detection and control component 400 installed on the annular main pipe 310 obtains the flow field pressure pulsation state through the high-frequency pressure transmitter 410, and sends it to the industrial control computer to drive the fast-response electromagnetic regulating valve 420 to perform flow modulation; the above structural system works together to build a dynamic fluid isolation barrier inside the furnace body main frame 100, which weakens the liquid bridge force adhesion effect of particles when they come into contact with the furnace wall from the physical source.

[0050] The flow guide ring 240 is made of silicon carbide material. The cross-sectional shape of the flow guide ring 240 is wedge-shaped and has a wedge tip 241. The wedge tip 241 points above the main frame 100 of the furnace body and is in close contact with the inner wall of the lining assembly 200. The flow guide ring 240 guides the airflow passing through the annular slit 230 to flow tangentially upward along the inner wall of the lining assembly 200 to form a wall-adhering air film.

[0051] The guide ring 240 is made of silicon carbide and is designed to resist the continuous erosion and wear of high-temperature particulate flow to maintain structural integrity. The wedge-shaped cross-section design of the guide ring 240 changes the injection vector of the secondary airflow. The wedge tip 241 points upward and is close to the inner wall of the liner assembly 200, forcing the airflow through the annular slit 230 to be deflected.

[0052] This structural layout utilizes the Coanda effect to guide the airflow tangentially upward along the inner wall of the lining component 200, thereby constructing a stable, high-shear-rate, wall-attached gas film in situ. This wall-attached gas film acts as a hydrodynamic barrier, physically isolating high-temperature suspended particles from the inner wall of the lining component 200. At the same time, it suppresses the near-wall temperature below the eutectic point of the high-iron components, eliminating the thermodynamic basis for the viscosity of semi-molten particles and effectively suppressing the initial deposition of low-eutectic materials on the refractory brick surface.

[0053] The adaptive negative pressure compensation valve 330 includes a valve seat 331 and an elastic diaphragm 333. The valve seat 331 is fixed to the inlet flange of the annular cavity 250. A vent hole 332 is opened in the center of the valve seat 331. The edge of the elastic diaphragm 333 is pressed against the valve seat 331. In its natural state, the elastic diaphragm 333 covers the vent hole 332 and leaves a preset gap 334. When the static pressure in the calcination chamber 210 decreases, the elastic diaphragm 333 deforms inward to increase the opening area of ​​the vent hole 332. The elastic diaphragm 333 is made of high-temperature resistant fluororubber material, and the height of the annular slit 230 is set to a preset slit height.

[0054] The adaptive negative pressure compensation valve 330 incorporates a purely mechanical fluid dynamics coupling mechanism in its structural design; the valve seat 331 is fixed to the inlet flange and supports an elastic diaphragm 333 made of high-temperature resistant fluororubber material, which can maintain a stable elastic modulus under high-temperature heat radiation environment; under normal production conditions, the elastic diaphragm 333 covers the vent hole 332 and only maintains the basic airflow injection of the preset gap 334.

[0055] The specific dimensions of the preset gap 334 are determined as follows: based on the minimum basic air flow rate required to maintain the back pressure of the elastic diaphragm 333 and prevent the backflow of high-temperature flue gas. Derivation is performed using the flow rate formula:

[0056] ;

[0057] in, For flow coefficient, A pressure difference is preset across the diaphragm. Calculate the required flow area based on the gas density. The width of the preset gap 334 is calculated based on the perimeter of the vent hole 332 of the valve seat 331 to ensure that only a small amount of airflow is provided to maintain the positive pressure of the gas path when the static pressure does not drop. When the local flow channel cross-section is narrowed due to micro-ringing inside the calcination chamber 210, according to Bernoulli's principle, the local flow velocity in this area increases sharply, thereby causing a significant drop in static pressure.

[0058] At this time, the pressure difference between the inside and outside of the furnace overcomes the inherent elastic restoring force of the elastic diaphragm 333, forcing the elastic diaphragm 333 to deform towards the inside of the furnace, spontaneously increasing the opening area of ​​the vent 332.

[0059] For the condition where the secondary airflow is modulated into a high-frequency pulsed flow, the mass and elastic damping of the elastic diaphragm 333 are specially configured so that its inherent response frequency is much lower than the high-frequency carrier frequency of the pulsed flow. Specifically, the elastic diaphragm 333 is simplified into a single-degree-of-freedom spring-mass-damping system, with its inherent response frequency as follows:

[0060] ;

[0061] in For the equivalent stiffness of the diaphragm, For diaphragm quality; to meet requirements far below high-frequency carrier frequencies Conditions, setting The equivalent stiffness of the diaphragm was determined through materials mechanics testing. Then, the required minimum configuration quality is calculated. This mass configuration is achieved by pre-embedding a counterweight 335 in the center of the diaphragm through vulcanization.

[0062] Meanwhile, according to the system damping ratio formula ,in The damping coefficient is determined by adjusting the carbon black filling ratio of the fluororubber. Specifically, the base compound of the fluororubber uses a terpolymer of vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene, and the carbon black is N990 semi-reinforcing thermal cracking carbon black. The filling ratio is set at 35 to 50 parts by weight of carbon black per 100 parts by weight of the base compound. This formulation range can stably achieve the desired damping ratio. Between 0.71 and 0.85, thus satisfying the requirement. The requirement is to effectively eliminate the resonance peak of the diaphragm under broadband excitation;

[0063] The low-pass filtering effect of the elastic diaphragm 333 is utilized so that the diaphragm will not flutter randomly when facing high-frequency pulsating airflow. Instead, it will maintain the average opening degree determined by the low-frequency static pressure difference by its mechanical inertia, thereby ensuring that the excitation energy of the high-frequency pulsed airflow can pass through the vent 332 into the furnace without attenuation.

[0064] This passive response mechanism based on fluid dynamics mismatch can avoid the risk of failure of electronic sensors in high-temperature dust environments, achieve flow compensation for local flow patterns, and ensure that areas with high ring formation can obtain sufficient cooling airflow. Among them, the preset slit height refers to the vertical distance between fluid channels between adjacent annular sections 220, and its physical significance lies in determining the initial jet kinetic energy and air film thickness of the secondary cooling airflow.

[0065] The parameter is determined by back-calculating the minimum attached-wall jet Reynolds number required for the Coanda effect based on the rated airflow of the main swirl outlet 120 and the inner diameter of the lining component 200. The specific mathematical model for this back-calculation is as follows: [The mathematical model is then defined as follows:] Set the attached-wall jet Reynolds number... ,in The minimum attached wall jet Reynolds number, characteristic length Taking the macroscopic turbulence scale of the main swirling flow field, the jet velocity ,in, The airflow allocated to this slit. For the inner lining component with an inner diameter of 200, For gas density, Let be the gas dynamic viscosity. Substituting it into the Reynolds number formula, we can derive the formula for calculating the preset slit height. ;

[0066] In the logic of constructing the wall-attached air film, if the preset slit height is too large, the initial kinetic energy of the airflow will not be enough to overcome the radial penetration force of the main swirling flow; if it is too small, the airflow resistance will increase sharply, resulting in ineffective injection. Therefore, this parameter plays a throttling and pressure-stabilizing role in ensuring that the wall-attached air film is stably attached to the inner wall.

[0067] The probe of the high-frequency pressure transmitter 410 extends into the annular main pipe 310. The fast-response electromagnetic regulating valve 420 is connected in series at the front end of the air inlet of the annular main pipe 310. The opening response time of the fast-response electromagnetic regulating valve 420 is less than the preset response time threshold. The annular main pipe 310, the branch pipe 320 and the annular cavity 250 constitute a secondary airflow channel. The airflow in the secondary airflow channel is modulated into a pulse flow by the fast-response electromagnetic regulating valve 420.

[0068] The high-frequency pressure transmitter 410 probe in the detection and control assembly 400 extends directly into the annular manifold 310, aiming to acquire minute pressure pulsation signals in the airflow channel with extremely low delay, providing high-fidelity raw data for subsequent spectrum analysis; the fast-response solenoid regulating valve 420 connected in series at the front end of the air inlet has an extremely short opening response time, which enables it to perform high-frequency flow cut-off and conduction actions.

[0069] The secondary airflow channel, consisting of the annular main pipe 310, branch pipe 320, and annular cavity 250, originally transported a continuous steady airflow. After the high-frequency modulation intervention of the fast-response electromagnetic regulating valve 420, the continuous flow was forcibly converted into a pulse flow with a specific frequency. This unsteady airflow input broke the flow field balance of the conventional constant air supply, providing a dynamic source for the subsequent application of dynamic aerodynamic excitation on the furnace wall surface.

[0070] The preset response time threshold refers to the maximum time delay required for the fast-response electromagnetic regulating valve 420 to reach the specified opening degree from receiving the control signal. Its significance is to ensure that the valve's operating frequency can cover and interfere with the turbulent main frequency of the main swirling flow field. The method for determining this threshold is: by extracting the highest effective harmonic frequency in the flow field acoustic impedance reference model under no-load conditions, one-quarter of the period of this frequency is taken as the preset response time threshold.

[0071] The criteria for determining effective harmonics are: the amplitude of the harmonic component is greater than or equal to 5% of the fundamental frequency amplitude, and its signal-to-noise ratio is greater than 3dB. The highest frequency harmonic that meets this condition is the highest-order effective harmonic frequency. In the modulated pulse flow control process, this threshold is used as the basis for hardware selection and control closed-loop judgment to ensure that the waveform of the pulse flow does not suffer serious distortion, thereby ensuring the effective transmission of high-frequency aerodynamic excitation force.

[0072] Example 2:

[0073] Please see Figure 1-5 Control methods for anti-ringing suspension calcining furnaces of kaolin for high-speed railways include:

[0074] S1. Under no-load conditions of the anti-ringing suspension calcining furnace, start the main swirl air outlet 120 and the secondary air supply component 300, and collect the first pressure pulsation data in the annular main pipe 310 through the high-frequency pressure transmitter 410.

[0075] S2. Perform spectrum analysis on the first pressure pulsation data using an industrial control computer to identify the fundamental frequency peak and its harmonic components, and establish a flow field acoustic impedance benchmark model.

[0076] S3. During the material feeding and production process, the second pressure pulsation data in the annular main pipe 310 is collected in real time by the high-frequency pressure transmitter 410, and the current power spectral density is obtained by the industrial control computer.

[0077] S4. The low-frequency characteristic energy and high-frequency substrate energy are extracted based on the current power spectral density by an industrial control computer, and the fluid impedance distortion coefficient is calculated.

[0078] S5. The industrial control computer determines whether the fluid impedance distortion coefficient is greater than or equal to a preset threshold. If it is greater than or equal to the preset threshold, the industrial control computer sends a modulation signal to the fast-response electromagnetic regulating valve 420. If it is less than the preset threshold, the process returns to step S3.

[0079] The control method provided in this embodiment uses fluid impedance spectroscopy analysis to invert the roughness state of the furnace wall. In the initial stage when the equipment is unloaded and the inner wall is clean, the main swirling air outlet 120 and the secondary air supply component 300 work together to build a stable cold swirling field. The high-frequency pressure transmitter 410 continuously collects the first pressure pulsation data in the annular main pipe 310. The industrial control computer performs a fast Fourier transform on the time domain signal to extract the fundamental frequency peak and its harmonic components unique to the clean state, which are used as the flow field acoustic impedance reference model under smooth boundary conditions.

[0080] The purpose of this model is to provide a reference standard representing ideal smooth boundary conditions when the micro-roughness of the furnace wall cannot be directly measured, for subsequent calculation of impedance distortion coefficient. In terms of logic structure and data flow, the model receives the pressure time-domain signal under no-load conditions as input, and after frequency domain mapping, outputs a feature vector containing the fundamental frequency, fundamental frequency amplitude, and harmonic attenuation rate, which serves as the reference fingerprint of the system.

[0081] Among them, harmonic attenuation rate The specific mathematical definition is: the average value of the logarithmic attenuation gradient of each harmonic amplitude in the spectrum relative to the fundamental frequency amplitude, and its calculation formula is:

[0082] ;

[0083] in, This is the fundamental frequency amplitude, in dB. For the first The amplitude of the first harmonic. The total order of the effective harmonics; this parameter physically characterizes the dissipation characteristics of the flow field energy transfer from low frequency to high frequency in the frequency domain; from a physical perspective, this model characterizes the ideal coupling state of the hydrodynamic oscillation and acoustic reflection characteristics of the main swirling flow field under the condition of a smooth rigid boundary without rings on the furnace wall, and establishes the inherent white noise base and energy distribution law of the characteristic turbulence of the system.

[0084] Meanwhile, under smooth boundaries, the frictional resistance and acoustic reflection coefficient of the fluid are at their minimum values. At this time, the fundamental frequency peak of the pressure pulsation corresponds to the macroscopic period of the main swirling flow, and the harmonic components correspond to the regular turbulent microstructure near the wall. When the wall roughness increases due to ring formation, the change in acoustic impedance will directly lead to the transfer of fundamental frequency energy to irregular high-frequency harmonics, thereby realizing the accurate mapping of the pressure pulsation frequency characteristics to the acoustic impedance and roughness state of the boundary layer.

[0085] During the material feeding and production stage, the high-frequency pressure transmitter 410 continuously monitors the second pressure pulsation data, and the industrial control computer calculates the current power spectral density in real time. The processor focuses on extracting the low-frequency surge characteristic energy that reflects the local narrowing of the flow channel, as well as the high-frequency white noise base energy that reflects the airflow friction noise. The fluid impedance distortion coefficient is calculated by the ratio of the two.

[0086] The specific calculation logic is as follows: the current power spectral density is divided into a preset low-frequency band and a high-frequency band; the specific basis for the preset low-frequency band and high-frequency band is: the fundamental frequency peak value identified in the flow field acoustic impedance reference model. As the baseline limit;

[0087] Specifically, the frequency range is in The interval is defined as the low-frequency band, which mainly contains the macroscopic pressure pulsation energy caused by changes in the flow channel cross-section. The extraction of low-frequency characteristic energy is specifically achieved by analyzing this low-frequency band. Power spectral density function within The low-frequency characteristic energy is obtained by performing definite integral operations. This integral value accurately represents the surge macroscopic energy contained in the low-frequency band;

[0088] The frequency range is The interval is designated as the high-frequency band. The Nyquist frequency is the system sampling frequency. To resolve the physical contradiction between the second and higher-order harmonics in the high-frequency band and the definition of background white noise, a comb-shaped notch filter logic is used when calculating the high-frequency substrate energy. Within, remove all center frequencies. , Integer and Bandwidth is Within the frequency band, only the remaining spectral components are integrated to extract the high-frequency base energy value; this process ensures that the denominator purely reflects the random background white noise generated by airflow friction, rather than deterministic harmonic components;

[0089] Combining the fundamental frequency amplitude and harmonic attenuation rate in the eigenvector, the low-frequency characteristic energy value is divided by the high-frequency fundamental energy value and multiplied by the ratio of the fundamental frequency amplitude to the harmonic attenuation rate to calculate the fluid impedance distortion coefficient. When micro-rings begin to form on the furnace wall, changes in the cylindrical boundary conditions lead to attenuation of high-frequency components and enhancement of low-frequency fluctuations. The industrial control computer compares the fluid impedance distortion coefficient with a preset threshold. Once the threshold is reached or exceeded, it determines that there are precursors to viscous deposition in the furnace wall boundary layer and then outputs a modulation signal to the fast-response electromagnetic regulating valve 420.

[0090] The preset threshold represents the impedance distortion state when the micro-rings on the furnace wall reach the critical thickness that causes local flow velocity variations. This threshold is determined by calibrating the flow field acoustic impedance reference model by introducing a disturbance of known size and extracting the distortion coefficient at this point.

[0091] The specific calibration process is as follows: In the high-frequency ring area of ​​the inner wall of the liner component 200 under no-load conditions, a thickness of [missing information] is manually applied. A hemispherical array of silicon carbide perturbation bodies was used to simulate the initial viscous deposition layer.

[0092] The disturbance array is evenly distributed in the annular area using an equilateral triangle staggered arrangement. The center-to-center distance between adjacent disturbances is set to 50mm to 80mm, and the overall distribution density is controlled between 150 and 400 disturbances per square meter. This specific arrangement and distribution density can accurately reproduce the true interference degree of the initial micro-rings on the acoustic impedance of the near-wall flow field.

[0093] The main swirl vent 120 is activated to reach the rated air volume. The pressure pulsation data at this time is collected by the high-frequency pressure transmitter 410, and the fluid impedance distortion coefficient at this time is extracted according to the aforementioned distortion coefficient calculation logic. The average value of the distortion coefficient is multiplied by a safety factor of 1.1 to 1.2 and set as the preset threshold. This equivalent mapping transforms the abstract critical thickness into a clear spectral energy ratio limit, ensuring the physical reproducibility of the calibration reference.

[0094] S5 and later include:

[0095] S601, The fast-response electromagnetic regulating valve 420 performs high-frequency opening and closing actions according to the modulation signal, converting the airflow entering the annular slit 230 from continuous flow to pulse flow;

[0096] S602. Periodic excitation force is generated in the wall-adhering gas film on the inner wall surface of the lining component 200 by using pulse flow, wherein the excitation force acts perpendicularly to the furnace wall deposit layer; the modulation signal is a pulse width modulation signal, wherein the carrier frequency of the pulse width modulation signal is set to be out of phase with the turbulent main frequency of the main swirling flow field in the calcination chamber 210.

[0097] Upon receiving a pulse width modulation signal, the fast-response solenoid valve 420 initiates a high-frequency opening and closing action, forcibly changing the airflow entering the annular slit 230 from a continuous flow to a pulsed flow. In order to overcome the mechanical inertia of conventional industrial solenoid valves and meet the physical action requirements of such high frequency and extremely low delay under high temperature conditions, the fast-response solenoid valve 420 uses a direct-acting piezoelectric ceramic servo valve or a high-frequency pulse valve driven by a voice coil motor. Its valve core mass is less than 50 grams, its inherent response frequency reaches more than 500 Hz, and its full-stroke opening and closing time is less than 2 milliseconds.

[0098] This hardware configuration ensures that the valve can accurately track the turbulent frequency of the main swirling flow field, which is usually in the range of 50Hz to 150Hz, and perform high-frequency actions without distortion. Regarding the carrier frequency setting of the pulse width modulation signal, the specific numerical relationship is as follows: the carrier frequency is set to be equal to the turbulent frequency of the main swirling flow field in the calcination chamber 210.

[0099] The specific method for obtaining the dominant turbulence frequency is as follows: the industrial control computer performs a fast Fourier transform on the real-time acquired second pressure pulsation data, extracts the frequency component with the largest amplitude within a preset low-frequency band, and uses this frequency component as the dominant turbulence frequency of the current flow field. This characterizes the macroscopic periodic oscillation frequency of the main swirling flow field; the inverse phase here does not refer to the frequency property, but rather to the pressure difference maximization modulation logic based on reverse pressure gradient injection; the industrial control computer analyzes the phase angle of the turbulent main frequency in real time. The specific analysis steps are as follows:

[0100] The industrial control computer performs a discrete Fourier transform on the real-time acquired second pressure pulsation data to obtain the turbulence dominant frequency. The corresponding complex Fourier coefficients ,in For the real part, Let i be the imaginary part, and i be the imaginary unit; then, the initial phase angle of this frequency component is calculated using the four-quadrant arctangent function. and map it to The phase angle is used to control the action phase of the fast-response electromagnetic regulating valve 420.

[0101] Considering the non-negligible transmission time of airflow from the electromagnetic regulating valve through the annular main pipe 310 and branch pipe 320 to the inner wall of the liner assembly 200. The industrial control computer calculates the phase lag angle of fluid transmission based on the current airflow sound velocity and transmission path length. ;

[0102] The current airflow sound velocity is obtained by real-time acquisition of the current airflow thermodynamic temperature using a high-temperature resistant thermocouple installed on the wall of the main swirling air outlet 120 or the calcining chamber 210. And using the ideal gas speed of sound formula Calculate the current airflow speed ;in The adiabatic index of the gas. The gas constant is obtained through the formula. The transmission time is calculated, where The calibrated fixed transmission path length from the electromagnetic control valve to the inner wall of the liner assembly 200;

[0103] The actual action phase compensation of the fast-response solenoid control valve 420 is precisely set. ; Utilizing the principle of reverse pressure gradient injection, this same-frequency anti-phase control with transmission delay compensation eliminates the phase lag characteristic of fluid transmission, ensuring that the pulsed airflow arrives at the furnace wall surface precisely at the phase when the local pressure in the main swirling flow field is in the low-pressure trough period, thereby creating the maximum instantaneous pressure difference, causing a violent collision of fluid momentum, and generating strong unsteady pressure oscillations; This pulsed flow continuously generates periodic excitation force inside the gas film attached to the wall, and this excitation force vertically penetrates the gas film and acts on the deposited layer on the furnace wall surface;

[0104] The eutectic material within the sediment layer experiences a sudden increase in stiffness under the rapid cooling effect of pulsed cold air, resulting in a significant thermal hysteresis effect that prevents it from synchronizing with the airflow frequency. This dynamic mismatch induces intense shear fatigue failure at the interface between the sediment layer and the refractory brick, causing microcracks to propagate in the unconsolidated initial sediment and eventually peel off. This aerodynamic excitation mechanism replaces mechanical bombardment, achieving active defense and removal of the sediment layer through hydrodynamic means. Furthermore, the aforementioned high-frequency hardware execution capability provides solid mechanical support for the real-time control logic of the algorithm and the expected aerodynamic excitation effect.

[0105] S5 is followed by: S701, when the local flow channel cross-section narrows in the calcination chamber 210, causing a decrease in static pressure, the adaptive negative pressure compensation valve 330 increases the opening degree by utilizing the pressure difference; S702, by increasing the opening degree of the adaptive negative pressure compensation valve 330, low-temperature pulse airflow is drawn into the ring-forming area for cooling and vibration stripping.

[0106] During active pneumatic excitation, if the speed of ring formation at a certain point on the furnace wall exceeds expectations, the narrowing of the local flow channel cross-section in the calcination chamber 210 will cause a more significant drop in static pressure. After sensing this pressure difference change, the adaptive negative pressure compensation valve 330 passively undergoes a larger displacement of its elastic diaphragm 333 to increase the opening degree of the vent 332. The increased opening degree allows this specific valve to draw in a low-temperature pulse airflow that far exceeds the normal flow rate and directly guide it to the area with the most severe ring formation.

[0107] The injected excess low-temperature pulsed gas flow not only accelerated the phase change cooling process of the eutectic but also significantly amplified the amplitude of the periodic excitation force in the region. This feedback mechanism based on spontaneous adjustment of physical state ensures that the system can automatically carry out high-intensity in-situ physical removal of abnormal knots without the need for precise sensor positioning, thereby improving the stability of the system under complex formulation fluctuation conditions.

[0108] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A suspension calcining furnace for preventing ring formation of kaolin used in high-speed rail, characterized in that, include: The furnace body main frame (100) is vertically fixed on the base (130). The main burner (110) is provided at the bottom center of the furnace body main frame (100). The main swirl air outlet (120) is provided along the tangential direction on the lower side wall of the furnace body main frame (100). The main swirl air outlet (120) is connected to the high temperature flue gas generator. The inner lining assembly (200) is located inside the main frame (100) of the furnace body. The inner lining assembly (200) is constructed of refractory bricks and encloses a cylindrical calcination chamber (210). The inner lining assembly (200) is divided into independent annular sections (220) in the vertical direction. An annular slit (230) is formed between adjacent annular sections (220). A guide ring (240) is installed at the annular slit (230). The secondary gas supply assembly (300) includes an annular main pipe (310) surrounding the outer wall of the main frame (100) of the furnace body, wherein the annular main pipe (310) is connected to the annular cavity (250) outside the lining assembly (200) through a branch pipe (320), and an adaptive negative pressure compensation valve (330) is provided at the connection between the branch pipe (320) and the annular cavity (250). The detection and control assembly (400) includes a high-frequency pressure transmitter (410) and a fast-response solenoid valve (420) mounted on the annular manifold (310). The high-frequency pressure transmitter (410) and the fast-response solenoid valve (420) are respectively connected to an industrial control computer, which controls the opening and closing of the fast-response solenoid valve (420).

2. The anti-ringing suspension calcining furnace for high-speed railway kaolin as described in claim 1, characterized in that, The guide ring (240) is made of silicon carbide material. The cross-sectional shape of the guide ring (240) is wedge-shaped and has a wedge tip (241). The wedge tip (241) points above the main frame (100) of the furnace body and is close to the inner wall of the lining assembly (200). The guide ring (240) guides the airflow through the annular slit (230) to flow tangentially upward along the inner wall of the lining assembly (200) to form a wall-adhering air film.

3. The anti-ringing suspension calcining furnace for high-speed railway kaolin as described in claim 1, characterized in that, The adaptive negative pressure compensation valve (330) includes a valve seat (331) and an elastic diaphragm (333). The valve seat (331) is fixed to the inlet flange of the annular cavity (250). A vent hole (332) is opened in the center of the valve seat (331). The edge of the elastic diaphragm (333) is pressed against the valve seat (331). In its natural state, the elastic diaphragm (333) covers the vent hole (332) and leaves a preset gap (334). When the static pressure in the calcination chamber (210) decreases, the elastic diaphragm (333) deforms inward to increase the opening area of ​​the vent hole (332).

4. The anti-ringing suspension calcining furnace for high-speed railway kaolin as described in claim 3, characterized in that, The elastic diaphragm (333) is made of high-temperature resistant fluororubber material, and the height of the annular slit (230) is set to a preset slit height.

5. The anti-ringing suspension calcining furnace for high-speed railway kaolin as described in claim 4, characterized in that, The probe of the high-frequency pressure transmitter (410) extends into the annular manifold (310), and the fast-response electromagnetic regulating valve (420) is connected in series at the front end of the air inlet of the annular manifold (310). The opening response time of the fast-response electromagnetic regulating valve (420) is less than the preset response time threshold.

6. The anti-ringing suspension calcining furnace for high-speed railway kaolin as described in claim 5, characterized in that, The annular main pipe (310), the branch pipe (320) and the annular cavity (250) constitute a secondary airflow channel, and the airflow in the secondary airflow channel is modulated into a pulse flow by the fast-response electromagnetic regulating valve (420).

7. A control method for an anti-ringing suspension calcining furnace for high-speed railway kaolin, applicable to the anti-ringing suspension calcining furnace for high-speed railway kaolin as described in claim 1, characterized in that, include: S1. Under no-load conditions, the main swirl vent (120) and the secondary gas supply assembly (300) are started in the anti-ring suspension calcining furnace, and the first pressure pulsation data in the annular main pipe (310) is collected through the high-frequency pressure transmitter (410). S2. The industrial control computer performs spectrum analysis on the first pressure pulsation data to identify the fundamental frequency peak and its harmonic components, and establishes a flow field acoustic impedance reference model. S3. During the material feeding and production process, the second pressure pulsation data in the annular main pipe (310) is collected in real time by the high-frequency pressure transmitter (410), and the current power spectral density is calculated by the industrial control computer. S4. The industrial control computer extracts low-frequency characteristic energy and high-frequency substrate energy based on the current power spectral density and calculates the fluid impedance distortion coefficient. S5. The industrial control computer determines whether the fluid impedance distortion coefficient is greater than or equal to a preset threshold. If it is greater than or equal to the preset threshold, the industrial control computer sends a modulation signal to the fast-response electromagnetic regulating valve (420). If it is less than the preset threshold, the process returns to step S3.

8. The control method for the anti-ringing suspension calcining furnace of kaolin for high-speed railway as described in claim 7, characterized in that, S5 followed by: S601, The fast-response electromagnetic regulating valve (420) performs high-frequency opening and closing action according to the modulation signal, converting the airflow entering the annular slit (230) from continuous flow to pulse flow; S602. The pulse flow generates a periodic excitation force in the wall-adhering gas film on the inner wall surface of the lining assembly (200), wherein the excitation force acts perpendicularly on the furnace wall deposit layer.

9. The control method for the anti-ringing suspension calcination furnace of kaolin for high-speed railway as described in claim 7, characterized in that, The modulation signal is a pulse width modulation signal, wherein the carrier frequency of the pulse width modulation signal is set to be opposite to the turbulent main frequency of the main swirling flow field in the calcination cavity (210).

10. The control method for the anti-ringing suspension calcination furnace of kaolin for high-speed railway as described in claim 7, characterized in that, Following S5, the following is also included: S701. When the local flow channel cross-section in the calcination chamber (210) narrows, causing a decrease in static pressure, the adaptive negative pressure compensation valve (330) increases the opening degree by utilizing the pressure difference. S702, by increasing the opening degree of the adaptive negative pressure compensation valve (330), a low-temperature pulse airflow is drawn into the ring-forming area for cooling and vibration stripping.

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