Manheim furnace combustion intensification process for reducing furnace temperature fluctuations

Abstract

The present application relates to the field of industrial furnace thermal regulation, and discloses a kind of manheim furnace combustion intensification process for reducing furnace temperature fluctuation, comprising: collecting real-time temperature of burner outlet flame root section and calculating the temperature time change rate, keeping the total flow of fuel and combustion air constant when the change rate exceeds the deviation threshold, reconstructing the momentum distribution ratio of airflow by adjusting the primary air speed and increasing the secondary air speed, using shear force to drive the interface of airflow to transition to parallel sliding state to form a aerodynamic force shield layer, and adjusting the negative pressure of the back of the furnace to assist the axial displacement of the combustion front, the present application reduces the transient thermal disturbance generated by reconstructing the heat release distribution of the combustion space during the adjustment process, solves the technical problem of local heat flux peak exceeding the conduction limit of the muffle furnace wall, suppresses the furnace temperature fluctuation and reduces the thermal stress damage of the furnace body, ensures the uniform heating of the muffle furnace, and improves the thermal robustness of the production process.

Description

Technical Field

[0001] This invention relates to a combustion enhancement process for a Mannheim furnace to reduce furnace temperature fluctuations, belonging to the field of industrial furnace thermal control technology. Background Technology

[0002] Currently, the Mannheim furnace, as the core indirect heat transfer kiln for potassium sulfate production, generates heat in its combustion chamber through a multi-channel burner and transfers the heat to the reaction zone via the silicon carbide muffle furnace wall. In the process of enhancing combustion to meet the demand for high yield, the industry generally increases the total supply of fuel and combustion air to increase the heat load per unit time. This conventional method is based on the static assumption that the distribution of combustion heat release is linearly related to the fuel supply, and can maintain a basic balance between furnace heat release and muffle furnace load heat absorption within the rated load range. As the combustion load is further increased, the local heat flux peak at the burner root and the flame axial coverage area will accumulate nonlinearly. Due to the inherent physical limitation of lateral heat conduction in silicon carbide muffle furnace material, the local heat release rate routinely exceeds the material's thermal conductivity. This spatial heat mismatch leads to drastic fluctuations in furnace temperature, which in turn causes surface damage or even structural cracking of the silicon carbide bricks under cyclic thermal stress, constituting a substantial physical barrier restricting the long-term high-load operation of the equipment.

[0003] To address the issue of localized overheating, industry experts have attempted to alter the flame morphology by continuously adjusting the momentum ratio of primary and secondary air in the burner, aiming to shift the heat release center towards the rear of the furnace. Analysis reveals that this linear, smooth adjustment method, within a specific range of changes in the inner and outer ring air velocity difference, can induce large-scale, Kelvin-to-Helmholtz unstable vortices due to variations in airflow shear force. The radial entrainment generated by these vortices enhances mass transfer efficiency in the root region, causing a transient retraction of the flame front before it completes controlled stretching. This localized deflagration phenomenon triggered by the adjustment action generates a secondary thermal shock, making it impossible for traditional air distribution strategies to smooth furnace temperature fluctuations without reducing the overall heat load. Existing improvements in thermal homogenization are largely limited to hardware optimizations such as roller morphology, failing to address the dynamics of the combustion field. For example, Chinese invention patent CN212374898U discloses a Mannheim reactor for potassium sulfate preparation, which reduces uneven local fire intensity by driving the internal reactant to rotate. However, such mechanical rotation schemes have limitations under high-temperature and heavy-load conditions: on the one hand, complex rotating mechanisms are prone to thermal deformation or bearing failure in the high-temperature radiation environment of silicon carbide bricks, resulting in poor physical stability of the equipment during long-term operation; on the other hand, the rotation only homogenizes heat in space, without addressing the transient flame retraction and secondary parasitic thermal shock caused by flow distortion at the burner root during enhanced combustion adjustment. This deviates from the underlying mechanical compensation method of combustion fluid dynamics, and cannot smooth furnace temperature fluctuations and ensure uniform heating of the muffle furnace while maintaining a constant total heat load.

[0004] Therefore, the technical problem to be solved by this invention is how to achieve spatial redistribution of combustion heat release without introducing flow field fluctuations by physically reshaping the momentum distribution logic of combustion air. Summary of the Invention

[0005] To address the problem in the background art where conventional air distribution regulation logic causes secondary thermal shock due to flame retraction induced by flow distortion, the technical solution of this invention is as follows: A Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations, comprising the following steps:

[0006] Step 101: Collect the real-time temperature of the flame root section at the burner outlet inside the Mannheim furnace and calculate the rate of change of the real-time temperature with respect to time.

[0007] Step 102: Determine whether the rate of change exceeds the preset fluctuation deviation threshold;

[0008] Step 103: When the rate of change exceeds the fluctuation deviation threshold, keep the total mass flow rate of fuel input and the total mass flow rate of combustion air at the current moment unchanged in order to shield the transient thermal disturbance caused by the large adjustment of flow rate.

[0009] Step 104: Obtain the primary air ejection velocity and secondary air ejection velocity of the burner, and lower the primary air ejection velocity while raising the secondary air ejection velocity to reconstruct the momentum distribution ratio of the primary and secondary air, while maintaining a constant total mass flow rate of the combustion air.

[0010] Step 105: Adjust the velocity difference between the primary air ejection velocity and the secondary air ejection velocity until the velocity difference exceeds the preset critical velocity difference threshold. Use fluid shear force to drive the interface between the primary air and the secondary air to change from a turbulent entrainment state to a parallel slip state, and form an aerodynamic shielding layer at the interface to block radial mixing.

[0011] Step 106: Adjust the negative pressure value of the exhaust gas and induced draft at the tail of the furnace according to the axial extension distance of the combustion front, and use the longitudinal pressure gradient formed in the furnace to assist the axial displacement of the combustion front in order to reduce the local heat flux density in the root section of the flame.

[0012] Preferably, in step 105, the parallel slip state is established through the following sub-steps: Step 1051, adjusting the velocity difference between the secondary air ejection velocity and the primary air ejection velocity so that an aerodynamic shielding layer is formed at the interface between the primary and secondary air; Step 1052, using the aerodynamic shielding layer to block the radial entrainment motion of the secondary air towards the flame root section, maintaining the stagnation point of the burner outlet recirculation zone above the preset stagnation lower limit value, and reducing the transient thermal fluctuations generated during the adjustment process through the reconstruction of the heat release distribution in the combustion space.

[0013] Preferably, in step 101, the real-time temperature is acquired by an infrared temperature sensor array arranged in the root section of the flame of the Mannheim furnace; the calculation of the rate of change of real-time temperature with respect to time includes: performing mean filtering on multiple acquisition points of the infrared temperature sensor array in the current sampling period to obtain temperature feature values, and comparing the deviation of temperature feature values ​​between two adjacent sampling periods.

[0014] Preferably, in step 104, reconstructing the momentum distribution ratio of primary air and secondary air includes: obtaining the transverse heat conduction capacity index of the muffle furnace wall inside the Mannheim furnace; and calculating the reduction step size of the primary air ejection velocity and the gain coefficient of the secondary air ejection velocity based on the real-time temperature fluctuation amplitude.

[0015] Preferably, in step 105, the duration of the parallel sliding state is dynamically adjusted based on the feedback signal from the rear temperature measurement section of the furnace; when the temperature of the rear temperature measurement section reaches the preset upper limit of heat transfer balance, the primary air jet speed is gradually restored to the original set value.

[0016] Preferably, in step 106, adjusting the exhaust and induced draft negative pressure value at the tail of the furnace includes: step 1061, monitoring the static pressure distribution curve along the furnace; step 1062, when the combustion front extends axially, correspondingly increasing the exhaust and induced draft negative pressure value to establish a controlled axial pressure gradient between the burner outlet and the tail of the furnace, preventing the combustion front from radially spreading within the furnace.

[0017] Preferably, it further includes: injecting periodic flow velocity pulse commands into the secondary air duct to cause the combustion front to generate axial reciprocating scouring motion inside the Mannheim furnace, so as to smooth the longitudinal temperature gradient of the outer wall of the muffle furnace inside the Mannheim furnace.

[0018] Preferably, the method further includes: obtaining asymmetric momentum distribution parameters among multiple burners; and independently adjusting the jet velocity ratio of primary air to secondary air for each burner according to the deviation of the thermal field distribution inside the Mannheim furnace, so as to eliminate local heat accumulation inside the Mannheim furnace.

[0019] Preferably, in step 103, the total mass flow rate of fuel input is kept constant by locking the opening of the electric regulating valve of the fuel supply pipeline; the total mass flow rate of combustion air is kept constant by locking the operating frequency of the combustion air blower or the position of the damper.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. In the combustion enhancement process of the Mannheim furnace, the decoupling effect between the momentum distribution matrix of the combustion air and the fuel diffusion rate is utilized. When the temperature rise rate in the root region of the furnace exceeds a predetermined suppression threshold, the total mass flow rate of fuel and combustion air is locked. By increasing the axial velocity difference between the secondary air and the primary air, a strong shear aerodynamic slip layer is established at the interface of the two airflows. This slip layer physically blocks the radial turbulent diffusion of fuel molecules into the high-oxygen zone, causing the unburned combustible mixture to undergo axial mass migration towards the tail of the furnace. This eliminates the common phenomenon of heat accumulation in the front section of the furnace in the Mannheim furnace under enhanced combustion conditions, reduces the local thermal stress impact on the silicon carbide muffle furnace bricks, and ensures the physical stability of the main structure of the kiln.

[0022] 2. This scheme uses a step-type velocity reconstruction mechanism to precisely avoid the Kelvin to Helmholtz unstable vortex region that is inevitably induced by the shearing of the inner and outer ring airflows during the traditional smooth regulation process. When an abnormal temperature change is detected in the first temperature measurement section, the system instantly increases the velocity difference between the secondary air and the primary air to a level greater than the preset critical velocity difference threshold. This nonlinear flow transition causes the interface between the inner and outer ring airflows to directly transition from a turbulent entrainment state to a parallel slip state. This eliminates the transient flame retraction and local deflagration side reactions that are easily generated in the early stage of the air distribution regulation action from the bottom layer of fluid mechanics. It transforms the high-speed combustion air into a rigid fluid sleeve that wraps around the fuel core, eliminating the secondary parasitic thermal shock brought about by the regulation process itself, and improving the robustness of the process system against thermal disturbances under extreme high load conditions.

[0023] 3. This invention establishes a logical correlation between the axial ejection velocity of the primary air duct and the stagnation stability of the burner outlet recirculation zone. When performing flow field stretching, the primary air velocity is monitored in real time and locked above the preset lower limit of flame stagnation limit. This ensures that the burner root always has a stable vortex structure during the axial migration of heat load, avoiding the risk of flameout due to excessive pursuit of flame stretching. On this basis, by adjusting the negative pressure value of the exhaust and induced draft at the tail of the furnace, the longitudinal pressure gradient is used to assist in the axial shift of the combustion interface, achieving a synergistic balance between combustion stability and spatial thermal field optimization, and broadening the production safety boundary of the Mannheim furnace without reducing the total heat input. Attached Figure Description

[0024] Figure 1 This is a flow chart of the Mannheim furnace temperature stabilization and combustion enhancement process of the present invention;

[0025] Figure 2 This is a schematic diagram of the evolution of combustion flow field morphology and thermal steady-state transformation in this invention.

[0026] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0028] This application provides a combustion enhancement process for a Mannheim furnace to reduce furnace temperature fluctuations. The process includes a thermal parameter acquisition stage, a flow field momentum reconstruction stage, and a longitudinal pressure gradient compensation stage. These stages form a closed loop through logical judgment and parameter feedback. While maintaining a stable total fuel input load, the process suppresses excessive local heat flux by physically intervening in the combustion air momentum distribution matrix. Under high-load continuous production conditions in the Mannheim furnace, the silicon carbide muffle furnace wall has physical limitations on lateral heat conduction, leading to heat accumulation in the flame stagnation area at the burner root, causing temperature fluctuations in the first temperature measurement section. An infrared temperature sensor array arranged in the flame root section of the Mannheim furnace collects the real-time temperature, and the system calculates the rate of change of this real-time temperature over time. The system uses a mean filtering process to process multiple sampling points of the infrared temperature sensor array within the current sampling period to obtain temperature characteristic values. By comparing the deviation of temperature characteristic values ​​between two adjacent sampling periods, the transient temperature rise rate is obtained. The sampling period is set to 100ms. If the temperature characteristic value of the current sampling period rises from 1150℃ to 1155℃ compared to the temperature characteristic value of the previous sampling period, the rate of change at the current moment is calculated to be 50℃ / s. This temperature characteristic value characterizes the dynamic evolution trend of heat flux in the flame root region.

[0029] When the rate of change exceeds the preset fluctuation deviation threshold, the root of the furnace is in a state of heat release and accumulation. The system locks the opening of the electric regulating valve of the fuel supply pipeline and the operating frequency of the combustion air fan to maintain a constant total mass flow rate of fuel input and total mass flow rate of combustion air at the current moment. The system obtains the primary air injection velocity of the burner. With secondary air ejection speed Based on the real-time fluctuation amplitude of the first temperature measurement section, the reduction step size of the primary air jet velocity and the gain coefficient of the secondary air jet velocity are calculated, and the primary air jet velocity is adjusted down accordingly. And increase the speed of the secondary air jet. Reconstruct the momentum distribution ratio between the primary and secondary winds, and the primary wind ejection velocity. With secondary air ejection speed The reverse regulation maintained a constant total heat load and changed the spatial distribution of combustion energy.

[0030] The burner flow field shear transition boundary parameter characterizes the critical velocity difference threshold at which the interface between the inner and outer annular airflows transitions from a turbulent entrainment state to a parallel slip state. The system sends flow rate commands to the primary and secondary wind channels to adjust the primary wind ejection speed. With secondary air ejection speed The speed difference is greater than the critical speed difference threshold within a single adjustment cycle. Set the current primary air jet speed The secondary air ejection velocity is 25 m / s. The critical velocity difference threshold is 35 m / s. The system adjusts the secondary air ejection speed to 20 m / s. At 46 m / s, the velocity difference is 21 m / s, which is greater than the critical velocity difference threshold. By driving the airflow interface from a turbulent entrainment state to a parallel slip state through shear force, an aerodynamic shielding layer is formed at the interface. Specifically, this invention utilizes the specific geometric contraction ratio of a coaxial dual-channel burner to create parallel initial flow fields at the primary and secondary air nozzles. When the velocity difference between the two exceeds a critical velocity difference threshold... Under the constraints of the narrow combustion space of the Mannheim furnace, the high-momentum secondary wind exerts a strong entrainment and envelopment effect on the primary wind, causing the momentum exchange between the two airflows at the interface to change from being dominated by large-scale vortex entrainment to being dominated by surface molecular diffusion. Due to the momentum rigidity generated by the secondary wind velocity at the moment of transition, the growth of Kelvin-Helmholtz instability in the flame root region is suppressed, thus forming a laminar slip zone with a thickness of millimeters. Maintained by an extremely high velocity gradient, it forms a physical aerodynamic shield layer, preventing fuel molecules from radially penetrating to the external high-oxygen zone before completing sufficient axial acceleration. This achieves spatial topological reconstruction of combustion heat release. This aerodynamic shield layer blocks radial mixing, reduces the diffusion rate of fuel molecules to the high-oxygen zone, and causes unburned combustible mixture to undergo axial mass migration towards the tail of the furnace, reducing the heat flux of the front section of the muffle furnace.

[0031] The system monitors the axial gas ejection velocity in the primary air duct. When the primary air ejection velocity... When the flame flow rate drops to the preset lower limit, the primary air jet velocity is locked. Maintaining the lower limit of the flame congestion limit, the system adjusts the negative pressure of the exhaust fan at the tail of the furnace according to the axial extension distance of the combustion front, monitors the static pressure distribution curve along the furnace, increases the negative pressure of the exhaust fan, and forms a longitudinal pressure gradient between the burner outlet and the tail of the furnace. Under the action of the longitudinal pressure gradient, the combustion front shifts towards the second temperature measurement section; the system inputs periodic flow velocity pulse commands to the secondary air channel, and the secondary air ejection velocity... The flame exhibits sinusoidal fluctuations around the baseline value, with low-frequency axial oscillations occurring in the core combustion heat release zone within the combustion chamber. The flame front reciprocates axially within the Mannheim furnace. For furnaces with multiple burners, the system acquires asymmetric momentum distribution parameters among multiple burner groups and independently adjusts the primary air ejection velocity of each burner based on the deviation in the transverse thermal field distribution within the furnace. With secondary air ejection speed jet velocity ratio The jet velocity ratio Secondary air ejection speed With the speed of the first air jet The ratio of the jet velocities of each burner Adjustments are made to change the lateral and longitudinal heat flow distribution, so that the transient temperature change rate of each heated surface on the outer wall of the muffle furnace converges to a preset range.

[0032] Axial extension distance of the combustion front The coordinates of the extreme heat intensity points captured by the infrared temperature sensor array along the longitudinal axis of the Mannheim furnace are used to determine the location. The system extracts the longitudinal physical location corresponding to the channel with the strongest output response electrical signal from the infrared temperature sensor array as the combustion heat release center. The axial extension distance is obtained by calculating the displacement vector of this longitudinal physical location relative to the burner outlet reference plane. The system is based on the axial extension distance. Adjust the frequency converter of the smoke exhaust fan; when the axial extension distance When the displacement is less than the extension threshold, the system initiates the precise compensation procedure for induced draft negative pressure based on the mass continuity equation and error negative feedback theory, and extracts the ideal axial limit characterizing the preset safe thermal field distribution as the target value. According to the formula Calculate the frequency output compensation increment of the induced draft fan inverter. ,in, Represents the frequency output compensation increment. This represents the longitudinal reference coordinate limit for maintaining uniform heating of the muffle furnace wall, and its value is defined within the physical depth dimension of the muffle furnace. This represents the proportional control gain coefficient that enables the variable frequency motor to accelerate its response, and is a positive real number. The differential damping coefficient represents the amplitude of high-frequency oscillations along the combustion front axis, where dt is the sampling time step and the system compensates for the frequency output increment. The duty cycle drive level signal is generated by superimposing it onto the current operating reference frequency. The controller increases the inverter output power of the flue gas induced draft fan to enhance the negative pressure extraction capability at the tail of the furnace. A controlled longitudinal static pressure gradient is established between the burner outlet and the tail of the muffle furnace. The aerodynamic force generated by this longitudinal static pressure gradient is used to drive the combustion front to shift towards the second temperature measurement section. In actual operation, the establishment of this longitudinal static pressure gradient directly changes the back pressure environment at the burner outlet. Because the Mannheim furnace cavity has a quasi-closed long tubular structure, the negative pressure fluctuations generated by the flue gas induced draft fan can be effectively converted into a steady flow bias along the furnace axis. This bias pressure and the dynamic pressure generated by the combustion jet itself are linearly related. By altering the pressure balance point in the downstream recirculation zone of the nozzle, an axial traction torque is applied to the flame front, which is in chemical reaction equilibrium. When the negative pressure at the tail of the furnace increases, this traction torque disrupts the original vector balance between flame propagation speed and local airflow speed, causing the high-temperature heat release center of the combustion reaction to undergo macroscopic displacement along the pressure gradient under the guidance of fluid dynamics. This achieves precise migration of the peak heat flux in physical space. Through this closed-loop negative pressure regulation mechanism based on thermal field morphology feedback, the system deviates the heat release center from the heat accumulation area at the front of the muffle furnace, thereby mitigating the risk of furnace temperature fluctuations caused by the local peak heat flux exceeding the thermal conductivity limit.

[0033] Example 1: When the Mannheim furnace system faces high-load continuous potassium sulfate production, the transverse thermal conductivity of the silicon carbide muffle furnace wall has a fixed upper limit. The transient heat release in the local space of the flame root section at the burner outlet is greater than the transverse thermal conductivity of the muffle furnace wall. The continuous accumulation of heat in this flame root section causes the temperature of the first temperature measurement section to fluctuate at high frequency. The transient change rate of the temperature characteristic value of the first temperature measurement section collected and calculated by the infrared temperature sensor array reaches 55℃ / s, and there is a risk of local overheating and melting. After the system detects that the change rate exceeds the preset fluctuation deviation threshold, it locks the opening of the electric regulating valve of the fuel supply pipeline and the operating frequency of the combustion air blower. The total mass flow rate of fuel input and the total mass flow rate of combustion air are kept constant. The system synchronously reduces the primary air injection speed of the burner. And increase the secondary air injection speed of the burner. The speed of the first air jet With secondary air ejection speed The speed difference increases and crosses the preset critical speed difference threshold. The flow field at the interface between the primary and secondary air flows changes from a turbulent entrainment state to a parallel slip state, forming an aerodynamic shield layer at the interface. This aerodynamic shield layer physically blocks the radial entrainment motion of the secondary air towards the flame root section. Under the constraint of this aerodynamic shield layer, the combustion front shifts axially towards the second temperature measurement section. The axial displacement of the combustion front causes the combustion heat release core area to deviate from the first temperature measurement section. The local heat flux density of the first temperature measurement section decreases, and the temperature characteristic value smoothly converges to the preset process safety range. The heat accumulation phenomenon in the front section of the muffle furnace is eliminated. The Mannheim furnace completes the reconstruction of the longitudinal heat flow spatial distribution of the furnace within the physical boundary of maintaining a constant overall fuel input heat load, and avoids local thermal stress damage to the muffle furnace wall.

[0034] Example 2: This example uses a 1:1 scale Mannheim furnace thermal simulation test platform to construct the test environment, including a silicon carbide muffle furnace simulator and a multi-channel DC burner. The temperature measurement signal acquisition frequency is set to 10Hz. This sampling frequency is adapted to the time constant and signal bandwidth of the thermal process, and is used to capture the heat flux changes caused by the transient displacement of the combustion front and balance the computational load of the control system. A 50Hz power frequency interference is actively superimposed at the temperature measurement signal input end, and the ambient background noise intensity is set to 20dB to simulate the electromagnetic environment and background noise of an industrial site. Multiple control groups are set up in the experiment. The control group adjusts the total mass flow rate of the fuel supply to smooth furnace temperature fluctuations, while the partially missing control group changes the primary air injection speed. With secondary air ejection speed The ratio of the two speeds is controlled to be within 15.0 m / s. The present invention adjusts the primary air ejection speed in the sample group. With secondary air ejection speed The speed difference crosses the critical speed difference threshold within a single adjustment cycle. Critical speed difference threshold The critical velocity difference threshold was determined to be 20.0 m / s through pre-calibrated cold-state flow field sweep. The critical physical quantity characterizing the transition of the airflow interface from being dominated by turbulent diffusion to being dominated by linear shear shielding.

[0035] The system continuously acquires temperature measurement data output by the sensor array. The sample group of this invention... (The sentence is incomplete and requires more context to translate accurately.) At that time, the radial entrainment eddies in the flame root region transform into axially stretched laminar slip surfaces, and the heat flux characteristic value of the first temperature measurement section changes from the initial... Descending to See Table 1, which records the thermal response parameters under different operating conditions.

[0036] Table 1: Comparative Data of Experiments on Reducing Furnace Temperature Fluctuations

[0037]

[0038] When the speed difference Crossing the critical speed difference threshold Subsequently, the temperature fluctuation rate showed a non-linear decreasing trend, changing from 14.8% in the partially missing control group to 69.5% in the sample group of this invention. The aerodynamic shielding layer formed at the interface between the primary and secondary air blocked radial heat transfer. When the velocity difference of the out-of-range control group II increased to 63.0 m / s, the decrease in temperature fluctuation rate entered the saturation zone, accompanied by a 32.4% increase in system energy consumption of the exhaust fan. The aforementioned parameter range constitutes an operating range that balances heat flux regulation and system robustness. The system maintains a constant total heat load, reconstructs the spatial distribution of heat release using flow field shear force, reduces local heat flux density through the aerodynamic shielding mechanism, and the transient temperature change rate of the muffle furnace heating surface converges to the process safety range.

[0039] Example 3: When the Mannheim furnace combustion system switches between multiple operating conditions, the difference in calorific value between different fuel batches causes a change in the initial heat release rate of the flame root section at the burner outlet. This change in the initial heat release rate causes a shift in the pre-set universal critical velocity difference threshold. The fixed velocity distribution ratio is difficult to maintain the stability of the airflow shielding layer, resulting in the first temperature measurement section facing the risk of transient thermal shock. The system then activates the critical velocity difference threshold. The dynamic calibration procedure acquires axial static pressure data along the burner nozzle within a 500.0 mm downstream range. A test airflow with a 2.0 m / s step gradient is injected into the primary and secondary air channels of the burner. The system calculates the static pressure gradient on both sides of the primary and secondary air interface. When the static pressure gradient abruptly changes from a positive value to zero and remains stable, the airflow interface transitions from a turbulent entrainment state to a parallel slip state. The system then extracts the primary air ejection velocity at the current moment. With secondary air ejection speed The speed difference is used as the current critical speed difference threshold. In specific implementation, the aforementioned axial static pressure data along the flow path is acquired through a miniature differential pressure sensor matrix pre-integrated in the burner head assembly. The sampling probes of this sensor matrix are arranged at the radial junction of the inner and outer rings at the outlets of the primary and secondary air channels, and are linearly arranged at equal intervals in the axial direction. By comparing the pressure difference changes of the inner and outer probes on the same axial section, the system constructs a pressure gradient profile of the flow field interface in real time. When a shear slip layer is formed between the two channels, the radial momentum exchange between the fluids is severely attenuated by the aerodynamic shielding effect, which manifests as the transient static pressure difference on both sides of the interface rapidly tending to balance. When the system captures that the pressure difference gradient drops to the preset zero drift range and the fluctuation frequency converges, it can determine that the flow regime has completed the transition and record the current wind speed difference value.

[0040] The system reconstructs the reduction step size of the primary air jet velocity based on the real-time fluctuation amplitude of the first temperature measurement section. and the gain coefficient of the secondary air ejection velocity The system is based on the real-time temperature change rate. Rate of change from preset benchmark Calculate the gain coefficient using the ratio The corresponding calculation formula is: And system settings The upper limit value is For the real-time temperature change rate at the current moment The rate of change is 60.5℃ / s and the preset baseline is used. Under the operating condition of 40.0℃ / s, the system calculates the gain coefficient according to the formula. The system multiplies the initial secondary air ejection velocity of 30.0 m / s by the gain coefficient 1.15, outputting a target secondary air ejection velocity of 34.5 m / s. The system then uses this target secondary air ejection velocity of 34.5 m / s and the updated critical velocity difference threshold as the basis for its output. That is, 20.5 m / s. The upper limit of the target primary air ejection velocity is derived and limited to 14.0 m / s. The system controls the fuel supply pipeline regulating valve and the combustion fan frequency to remain unchanged, and synchronously issues speed regulation commands to the primary air distribution baffle and the secondary air distribution baffle to reconstruct the momentum distribution ratio of the primary air and secondary air in the burner. The aerodynamic shielding layer at the airflow interface is then formed and blocks the radial diffusion of fuel. The peak heat flux generated by the combustion front is transferred to the tail of the muffle furnace, so that the Mannheim furnace maintains a stable distribution of heat release space under the condition of fluctuating fuel properties.

[0041] Example 4: Before the newly built Mannheim furnace is put into operation, the system performs spatial thermal mapping calibration between the infrared temperature sensor array and the thermocouple reference value on the inner surface of the silicon carbide muffle furnace wall. Under quasi-isothermal steady-state conditions in the furnace, the system collects radiation energy data output by the infrared temperature sensor array at multiple temperature measurement points. And mapped to equivalent temperature values Simultaneously, extract the muffle furnace wall embedded in the corresponding location. Actual wall temperature value fed back by the thermocouple The system establishes a global temperature correction compensation matrix by calculating the deviation distribution between the two. This matrix is ​​used to offset the measurement errors caused by the sensor installation angle deviation and the non-uniformity of the thermal emissivity of the outer wall of the muffle furnace, so that the calculated real-time temperature change rate can characterize the thermal balance state inside the muffle furnace.

[0042] When the system faces changes in burner specifications or furnace material, the system initiates an offline procedure for acquiring critical flow field parameters before the formal operation of the enhancement program. Under cold conditions, the system introduces airflow at the rated mass flow rate into the primary and secondary air channels and acquires dynamic pressure signals collected at pressure sampling points along the burner axis. With static pressure signal And calculate the amplitude of turbulence intensity fluctuations on both sides of the interface. The system monitors the process of increasing secondary wind speed. The numerical evolution trend, when The first derivative in When a step decrease occurs within the sampling window, the flow field is determined to have transitioned from a turbulent state to a parallel slip state with isolation characteristics, and the system records the primary wind speed at this time. With secondary wind speed The critical velocity difference threshold is determined by subtracting the two values. This calibration data is stored in the controller's non-volatile memory as a trigger criterion for the online adjustment logic.

[0043] Example 5: During the commissioning of a Mannheim furnace equipped with four sets of DC burners, the physical positional differences of each burner relative to the main exhaust port resulted in an asymmetrical distribution of the gravitational field of the flue gas along the furnace. The longitudinal temperature gradient deviation between the first and second temperature measurement sections exceeded 150.0℃. The system smoothed the heat release gradient by initiating a secondary air pulse frequency calibration program, and the controller obtained the equivalent thermal diffusivity of the muffle furnace wall. Characteristic thermal inertia time under current combustion conditions The system calculates the reference oscillation frequency of the secondary wind pulse. Its calculation formula is ,in, It is a dimensionless frequency adjustment constant with a value range of 0.8 to 1.2, for... It is 120.0s and Under the condition of 0.83, the system determines the reference oscillation frequency. The system controls the secondary air ejection speed at 0.01Hz. Based on the periodic fluctuations of the sine waveform between 45.0 m / s and 55.0 m / s, the flame front axially scours the inner wall of the muffle furnace, accelerating the heat transfer process in the middle and rear of the muffle furnace through physical intervention.

[0044] During the multi-burner coordinated control phase, the system utilizes an asymmetric momentum distribution protocol to balance the transverse thermal field within the furnace. The controller collects wall temperature data for the corresponding regions of the four burners and calculates the deviation of the wall temperature in each region relative to the global average temperature. ,in The system uses burner index numbers, with values ​​of 1, 2, 3, and 4, to calculate the jet velocity ratio of the corresponding burner based on the deviation in each region. The correction amount is the system setting of the jet velocity ratio. By changing the secondary air ejection speed The system uses weights to achieve differentiated compensation based on the formula. Adjust the opening of the secondary air distribution dampers on each branch, among which, As a reference secondary air ejection velocity, The dimensionless thermal field balance gain factor. Assuming a global average temperature, if the wall temperature deviation in the area where the third burner is located is +25.5℃, the system reduces the secondary air ejection velocity gain of the burner to shorten the flame axial length, thereby reducing the local heat flux input in that area and lowering the transverse temperature range of the muffle furnace inner wall to within 12.5℃.

[0045] In the continuous operation stability verification of the Mannheim furnace production line, the system maintains the stagnation point in the burner outlet recirculation zone at a preset safe stagnation displacement through a flow field reconstruction procedure; the safe stagnation displacement... The reference point is calibrated at a distance of 22.5 mm axially from the physical nozzle of the burner; this physical coordinate corresponds to the equilibrium position where the recirculation entrainment momentum and the jet shear momentum completely cancel each other out; the system adjusts the primary air ejection velocity in real time. With secondary air ejection speed The velocity difference is within the range of 21.5 m / s to 26.5 m / s; the aerodynamic shielding layer at the flow field interface maintains a continuous and rigid physical morphology; this shielding layer blocks the radial mass exchange at the flame root in the secondary wind direction; the stagnation point of the heat release core area is locked at 23.8 mm and the displacement deviation is reduced to within 1.5 mm; due to the high-precision displacement constraint of the stagnation point position; the local heat flux distribution in the flame root section remains spatially stable; the transient temperature rise rate of the muffle furnace heating surface during the enhanced combustion start-up stage decreases from 55.0℃ / s to about 5.0℃ / s; the above engineering specifications confirm the effectiveness of stagnation point locking in suppressing parasitic disturbances of the adjustment action in improving system robustness.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0047] Finally, 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 combustion enhancement process for a Mannheim furnace to reduce furnace temperature fluctuations, characterized in that, Includes the following steps: Step 101: Collect the real-time temperature of the flame root section at the burner outlet inside the Mannheim furnace and calculate the rate of change of the real-time temperature with respect to time. Step 102: Determine whether the rate of change exceeds the preset fluctuation deviation threshold; Step 103: When the rate of change exceeds the fluctuation deviation threshold, keep the total mass flow rate of fuel input and the total mass flow rate of combustion air at the current moment unchanged in order to shield the transient thermal disturbance caused by the large adjustment of flow rate. Step 104: Obtain the primary air ejection velocity and secondary air ejection velocity of the burner, and lower the primary air ejection velocity while raising the secondary air ejection velocity to reconstruct the momentum distribution ratio of the primary and secondary air, while maintaining a constant total mass flow rate of the combustion air. Step 105: Adjust the velocity difference between the primary air ejection velocity and the secondary air ejection velocity until the velocity difference exceeds the preset critical velocity difference threshold. Use fluid shear force to drive the interface between the primary air and the secondary air to change from a turbulent entrainment state to a parallel slip state, and form an aerodynamic shielding layer at the interface to block radial mixing. Step 106: Adjust the negative pressure value of the exhaust gas and induced draft at the tail of the furnace according to the axial extension distance of the combustion front, and use the longitudinal pressure gradient formed in the furnace to assist the axial displacement of the combustion front in order to reduce the local heat flux density in the root section of the flame.

2. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, In step 105, the parallel slip state is established through the following sub-steps: Step 1051, adjust the velocity difference between the secondary air ejection velocity and the primary air ejection velocity so that an aerodynamic shielding layer is formed at the interface between the primary and secondary air; Step 1052, use the aerodynamic shielding layer to block the radial entrainment motion of the secondary air towards the flame root section, maintain the stagnation point of the burner outlet recirculation zone above the preset stagnation lower limit, and reduce the transient thermal fluctuations generated during the adjustment process by reconstructing the heat release distribution in the combustion space.

3. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, In step 101, the real-time temperature is acquired by an array of infrared temperature sensors arranged in the root section of the flame in the Mannheim furnace. Calculating the rate of change of real-time temperature over time involves: performing mean filtering on multiple sampling points of the infrared temperature sensor array within the current sampling period to obtain temperature characteristic values, and comparing the deviation of temperature characteristic values ​​between two adjacent sampling periods.

4. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, In step 104, reconstructing the momentum distribution ratio of primary air and secondary air includes: obtaining the transverse heat conduction capacity index of the muffle furnace wall inside the Mannheim furnace; and calculating the reduction step size of the primary air ejection velocity and the gain coefficient of the secondary air ejection velocity based on the real-time temperature fluctuation amplitude.

5. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, In step 105, the duration of the parallel sliding state is dynamically adjusted based on the feedback signal from the rear temperature measurement section of the furnace; when the temperature of the rear temperature measurement section reaches the preset upper limit of heat transfer balance, the primary air jet speed is gradually restored to the original set value.

6. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, In step 106, adjusting the exhaust and induced draft negative pressure value at the tail of the furnace includes: step 1061, monitoring the static pressure distribution curve along the furnace; step 1062, when the combustion front extends axially, correspondingly increasing the exhaust and induced draft negative pressure value to establish a controlled axial pressure gradient between the burner outlet and the tail of the furnace, preventing the combustion front from radially spreading in the furnace.

7. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, Also includes: Periodic flow velocity pulse commands are injected into the secondary air duct to cause the combustion front to generate axial reciprocating scouring motion inside the Mannheim furnace, thereby smoothing the longitudinal temperature gradient on the outer wall of the muffle furnace inside the Mannheim furnace.

8. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, Also includes: Obtain the asymmetric momentum distribution parameters among multiple burners; based on the deviation of the thermal field distribution inside the Mannheim furnace, independently adjust the jet velocity ratio of primary air to secondary air for each burner to eliminate local heat accumulation inside the Mannheim furnace.

9. The Mannheim furnace combustion enhancement process for reducing furnace temperature fluctuations according to claim 1, characterized in that, In step 103, the total mass flow rate of fuel input is kept constant by locking the opening of the electric regulating valve of the fuel supply pipeline; the total mass flow rate of combustion air is kept constant by locking the operating frequency of the combustion air blower or the position of the damper.

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