A method for discharging a vertical cooling device based on overall flow

Abstract

The present application belongs to the technical field of metallurgical sinter cooling equipment, and particularly relates to a vertical cooling device discharging method based on overall flow. The method first collects high-temperature bulk material full-temperature-range dynamic friction angle data, matches a design cross-sectional area relative shrinkage rate constant exponential curve unloading area, limits the wall surface constraint half-apex angle to meet the bulk material synchronous flow condition; then constructs a multi-parameter collaborative constraint system containing bulk material flow rate and water equivalent ratio, establishes a dimensionless overall flow stability criterion function; obtains global temperature data through layered multi-point temperature measurement, evaluates funnel flow and tubular flow abnormalities in two-dimensional temperature standard deviation within and between layers, and combines the criterion function to adaptively adjust the forced discharging speed and layered cooling air volume to form a closed-loop control. The present application can stably maintain the piston type overall flow, solve the existing vertical cooling partial flow and uneven cooling problems, and improve the cooling uniformity and reduce the energy consumption.

Description

Technical Field

[0001] This invention belongs to the technical field of metallurgical sintering cooling equipment, and particularly relates to a material discharge method for a vertical cooling device based on overall flow. Background Technology

[0002] The high-temperature cooling process for sintered ore and pellets in the metallurgical industry is a key link in smelting production. Vertical cooling devices are widely used due to their advantages of small footprint and high heat exchange efficiency. The uniformity of the flow of bulk materials in the cooling chamber directly determines the temperature consistency of the finished product, cooling energy consumption, and the stable operation capability of the equipment. Stable piston-type integral flow is the core foundation for ensuring continuous and large-scale metallurgical production.

[0003] The current mainstream vertical cooling device adopts a cone-shaped fixed unloading hopper with a single gravity discharge structure. It relies on a fixed cone angle to achieve the natural fall of loose material. The cooling air volume adopts a unified overall air supply mode. During operation, the discharge volume is adjusted manually by fixing the opening degree. There is no stratified temperature monitoring method. The unloading structure is not adapted to the friction characteristics of loose material, and no parameter linkage control logic for flow and heat exchange coupling is established.

[0004] The existing solutions described above have the following shortcomings:

[0005] 1. The existing conical discharge cone has a fixed cone angle, which is not matched to the dynamic wall friction characteristics of high-temperature bulk materials. The bulk materials are severely stuck on the wall, which easily forms a funnel flow or tubular flow with high central flow velocity and stuck material on the side wall, and cannot form a stable overall flow. The flow constraint in the upper and lower sections of the linear cone is uneven, which easily leads to local stuck material and poor overall flow uniformity.

[0006] 2. The existing solution relies solely on gravity for natural material discharge, which cannot be precisely controlled. There is no method for stratified temperature monitoring and quantitative flow assessment, making it impossible to identify abnormal conditions such as flow deviation and tubular flow in a timely manner. There is no closed-loop feedback regulation logic, resulting in large temperature differences of materials at the same height and in the vertical direction, and poor cooling uniformity.

[0007] 3. The existing solution lacks a coordinated constraint mechanism for flow and heat exchange. The air volume and discharge speed are adjusted independently, which can easily lead to problems such as excessive air volume disturbing the material layer or insufficient air volume failing to meet cooling standards, resulting in high operating energy consumption. Furthermore, there is no precise correction method for unilateral flow deviation, leading to low efficiency in correcting abnormal operating conditions. Summary of the Invention

[0008] The purpose of this invention is to address the problems mentioned in the background art by providing a discharge method for a vertical cooling device based on overall flow.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a discharge method for a vertical cooling device based on overall flow, comprising the following steps:

[0010] Data on the dynamic friction angle characteristics of high-temperature bulk materials during the entire cooling temperature range were collected to obtain the dynamic internal friction angle and dynamic wall friction angle at different temperatures.

[0011] Based on the characteristic data, the flow matching design of the unloading area of ​​the cooling device is carried out. The flow cross-sectional area of ​​the unloading area is configured along the vertical height in a form with a constant relative shrinkage rate of cross-sectional area. This ensures that the wall constraint half-apex angle at any height in the unloading area is less than or equal to 90° minus the maximum dynamic wall friction angle of the high-temperature bulk material throughout the entire temperature range, thereby constraining the bulk material to form a piston-like integral flow.

[0012] A multi-parameter collaborative constraint system was constructed to establish the matching relationship between the average flow velocity of bulk material at the outlet of the unloading zone and the contraction characteristics of the unloading zone, as well as the constraint relationship between the cooling air and bulk material water equivalent ratio and the overall flow stability. A dimensionless overall flow stability criterion function and the corresponding threshold range were set.

[0013] Variable frequency forced discharge is performed at the discharge port at the bottom of the unloading area to actively and quantitatively control the discharge rate of bulk materials;

[0014] Temperature data from multiple spatial locations within the cooling device are collected in layers to construct multi-dimensional temperature distribution characteristics.

[0015] Based on multi-dimensional temperature distribution characteristics, combined with the overall flow stability criterion function, the overall flow state of bulk materials is quantitatively evaluated;

[0016] Based on the evaluation results, the forced discharge speed and stratified cooling air volume are adaptively adjusted to keep the overall flow stability criterion function within the preset threshold range, thus forming a self-feedback closed-loop control of the overall flow condition.

[0017] Furthermore, the variation of the flow cross-sectional area of ​​the unloading zone along the vertical height follows an exponential curve pattern, satisfying the following relationship:

[0018]

[0019] In the formula, This refers to the cross-sectional area of ​​the flow passage at the corresponding height of the unloading zone. The coordinates represent the height of the unloading area, with the origin at the intersection of the top surface of the unloading area and the cooling section, and the vertical downward direction as the positive direction. This is the initial flow cross-sectional area at the top surface of the unloading zone; The relative shrinkage rate of the cross-sectional area is a constant negative value with dimensions in meters. -1 , characterizing the relative decay rate of the flow cross-sectional area per unit height;

[0020] The wall constraint half-apex angle is the angle between the generatrix of the inner wall surface of the axial section of the unloading zone and the vertical direction, determined by calibration parameters. The numerical matching of the wall constraint half-apex angle size.

[0021] Furthermore, the acquisition of dynamic friction angle characteristic data specifically includes: setting up test conditions with no less than 5 temperature gradients to cover the entire temperature range of high-temperature bulk materials from feed temperature to discharge temperature, measuring the dynamic internal friction angle and dynamic wall friction angle of high-temperature bulk materials at each temperature, and fitting the dynamic wall friction angle-temperature correlation characteristic curve.

[0022] Wall-constrained half-apex angle Quantitative constraints must be met: ,in, This represents the maximum dynamic wall friction angle of high-temperature bulk materials across the entire temperature range.

[0023] Furthermore, a multi-parameter collaborative constraint system is constructed, specifically including:

[0024] Define the shrinkage characteristic parameters of the unloading zone ,in, The cross-sectional area of ​​the unloading area outlet is [area value missing]. This refers to the cross-sectional area of ​​the unloading area's inlet flow passage. This refers to the effective vertical height of the unloading area;

[0025] Establish rate matching rules: average flow velocity of bulk material at the outlet section of the unloading zone. With shrinkage characteristic parameters There is a positive correlation, that is, the shrinkage characteristic parameter The smaller the size, the more drastic the contraction of the unloading zone, corresponding to the allowable average flow velocity of the bulk material. The lower;

[0026] Define the equivalent ratio parameter of cooling air to bulk water. ,in, This represents the total mass flow rate of the cooling air. For the quality handling capacity of high-temperature bulk materials, The specific heat capacity of the cooling air at constant pressure. The specific heat capacity at constant pressure for high-temperature bulk materials;

[0027] Introducing the reference discharge flow rate under rated operating conditions Compared with the benchmark shrinkage characteristic parameters Construct a dimensionless global flow stability criterion function ,in , For preset weighting coefficients, The value range is 0.4 to 0.6. The value range is 0.4 to 0.6, and + =1;

[0028] Set the overall flow compliance threshold range as follows ,in , Determined by cold-state bulk material integral flow calibration test.

[0029] Furthermore, the threshold range of the overall flow stability criterion satisfies a quantitative constraint: the ratio of cooling air to bulk water equivalents. The value range is 1.0~1.3, which represents the average velocity of the bulk material at the outlet section of the unloading area. With shrinkage characteristic parameters The matching relationship satisfies the Froude number of bulk material flow. ;

[0030] The Froude number for bulk material flow is calculated using the following formula:

[0031]

[0032] in, Let g be the average velocity of the bulk material at the outlet section of the unloading zone, and g be the acceleration due to gravity. The equivalent diameter of the outlet section of the unloading zone;

[0033] When the overall flow state is determined to be deteriorated, or the overall flow stability criterion function is used... When the flow deviates from the preset threshold range, the forced discharge speed is reduced in increments of 5% to 10% of the rated discharge speed to correct the flow state. Simultaneously, the cooling airflow in the corresponding height area is increased in increments of 5% to 8% of the rated airflow in the corresponding height area, until the criterion function is reached. Regression to the preset threshold range.

[0034] Furthermore, the temperature data acquisition method is as follows: at least three temperature measuring layers are arranged in the vertical height direction of the cooling device, and at least four temperature measuring points are evenly arranged in the circumferential direction of each temperature measuring layer. Each temperature measuring layer is matched with the corresponding height zone air chamber. The temperature data of the whole area is obtained by synchronously measuring the temperature at multiple height and multiple circumferential points.

[0035] Quantitative assessment of the overall flow state of bulk materials includes:

[0036] Before determining the deterioration of the flow state, first check whether the feed temperature, the uniformity of the top material distribution, and the air pressure of each layer of air chamber are within the normal operating range, and eliminate temperature abnormalities caused by non-flow factors such as material distribution deviation, air chamber blockage, and feed temperature fluctuation.

[0037] Calculate the intra-layer temperature standard deviation of all temperature measurement points within the same temperature measurement layer. ;

[0038] Calculate the standard deviation of the interlayer temperature difference of the average temperature difference between two adjacent temperature measurement layers. ;

[0039] When the intralayer temperature standard deviation of any layer >25℃, or standard deviation of interlayer temperature difference When the temperature is above 30℃, an abnormal flow state of funnel flow, including tubular flow, is formed inside the device, and the overall flow state deteriorates.

[0040] Furthermore, when the overall flow state is determined to have deteriorated, the adaptive adjustment specifically includes:

[0041] When the standard deviation of the temperature within a single temperature measuring layer exceeds the standard, the forced discharge speed of the discharge port is reduced and the cooling air volume of the corresponding height area of ​​the temperature measuring layer is increased; when at least two symmetrical discharge ports are set at the bottom of the unloading area and the temperature deviation is concentrated on one side of the cross section, the discharge ports are controlled to form a differential speed operation mode, and the discharge speed on the side with higher temperature is increased by 10% to 30% compared with the other side, breaking the skewed funnel flow channel.

[0042] When the standard deviation of the interlayer temperature difference exceeds the standard, the overall forced discharge speed should be reduced first, the bulk material cooling residence time should be extended, and the total cooling air volume should be increased simultaneously according to the water equivalent ratio matching principle.

[0043] Continue adjusting until the standard deviation of intralayer temperature is ≤20℃ and the standard deviation of interlayer temperature difference is ≤25℃, to maintain stable operating parameters.

[0044] Furthermore, the forced discharge operation specifically adopts a discharge drive mechanism with variable frequency control. The high-temperature bulk material flowing out of the discharge port is subjected to continuous and controllable mechanical thrust through variable frequency drive. The discharge speed is quantitatively controlled by adjusting the average flow velocity of the bulk material at the outlet section of the unloading zone. When multiple discharge ports are set, each discharge port adopts independent variable frequency drive to achieve differential speed operation.

[0045] Furthermore, the high-temperature bulk material is metallurgical sintered ore or pellet granular material with a particle size range of 5~50mm.

[0046] Furthermore, the relative shrinkage rate of the cross-sectional area The absolute value is controlled between 0.05 and 0.15m. -1 Within the unloading zone, the outlet cross-sectional area and the inlet cross-sectional area satisfy a quantitative matching relationship:

[0047]

[0048] In the formula, This represents the minimum dynamic wall friction angle for high-temperature bulk materials across the entire temperature range. This is a structural correction factor, with a value ranging from 0.6 to 0.8. The overall value range is 0.3 to 0.6.

[0049] Compared with existing technologies, the advantages of this invention are:

[0050] 1. This invention collects dynamic friction angle data of high-temperature bulk materials across the entire temperature range, matches and designs a constant exponential shrinkage unloading zone, and limits the wall constraint half-apex angle to be less than the residual friction angle, thereby eliminating material stagnation on the wall from a structural perspective. Compared with traditional linear cone buckets, the exponential curve structure provides more uniform flow constraint across the entire height range, and can maintain the overall piston-like flow of bulk materials throughout the process, solving the defects of traditional fixed cone buckets that cannot adapt to the friction characteristics of bulk materials and the turbulent flow state.

[0051] 2. This invention achieves forced quantitative material discharge by independently driving the discharge mechanism with variable frequency, constructs a three-dimensional temperature distribution feature by arranging multiple temperature measurement points in layers, and quantitatively judges abnormal flow states by using the temperature standard deviation in both the intra-layer and inter-layer dimensions. It can use multi-discharge port differential speed control to address unilateral flow deviation, and adaptively adjust the discharge rate and layered cooling air volume in steps. Combined with hysteresis control logic, it avoids frequent fluctuations in operating conditions, achieves balanced temperature control across the entire domain, and solves the defects of traditional gravity unloading, such as lack of precise control and large material temperature differences.

[0052] 3. This invention constructs a multi-parameter collaborative constraint system that couples unloading shrinkage characteristics, bulk material flow rate, cooling air and bulk material water equivalent ratio, and combines it with Froude number low disturbance constraint to establish a linear overall flow criterion function to link and regulate air volume and discharge speed; by determining the criterion threshold through cold calibration, the control basis is more reliable, and the flow characteristics and heat exchange efficiency are matched in a coordinated manner, avoiding the material layer disturbance or insufficient cooling caused by single parameter adjustment, and effectively reducing the energy consumption of equipment operation. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the overall process of a discharge method for a vertical cooling device based on overall flow provided by the present invention;

[0054] Figure 2 This is a schematic diagram of the flow state assessment and degradation triggering decision-making process in a vertical cooling device discharge method based on overall flow provided by the present invention.

[0055] Figure 3 This is a schematic diagram of the adaptive adjustment process for flow state deterioration in a vertical cooling device discharge method based on overall flow provided by the present invention. Detailed Implementation

[0056] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0057] This embodiment takes the vertical cooling process of metallurgical sintered ore particles as an example to fully explain the discharge method of the vertical cooling device based on overall flow. In this embodiment, the high-temperature bulk material is metallurgical sintered ore particles with a particle size range of 5~50mm. The vertical cooling device used is a fixed vertical cylindrical structure with a straight cooling section at the top and a converging discharge zone at the bottom. Two independent discharge ports are symmetrically arranged at the bottom of the discharge zone. Cooling air is supplied independently in layers along the vertical height, and each layer of air chamber is matched with a temperature measurement area at the corresponding height.

[0058] In this method, "overall flow" refers to a piston-like flow pattern where the bulk material moves synchronously downwards across the entire cross-section. It lacks a wall-mounted stagnant layer and a central funnel-shaped rapid flow channel, representing the optimal flow state for cooling uniformity. The dynamic wall friction angle refers to the critical shear angle between the bulk material and the wall material under shear flow conditions, distinct from the static accumulation friction angle. The determination is based on the test procedures for internal friction angle and wall friction angle in the "Standard for Shear Test Methods of Bulk Materials" (or equivalent standards such as ASTM D6128), and is performed using a high-temperature annular shear apparatus at a constant shear rate of 1 mm / min. The wall material sample plate used for testing is consistent with the actual material of the unloading area wall in the device, and the surface roughness is the same as in the actual engineering project.

[0059] like Figure 1 As shown, a discharge method for a vertical cooling device based on overall flow includes the following steps:

[0060] S1. Collect dynamic friction angle characteristic data of high-temperature bulk materials throughout the entire cooling temperature range to obtain the dynamic internal friction angle and dynamic wall friction angle at different temperatures.

[0061] Specifically, the dynamic internal friction angle refers to the critical shear angle when relative sliding occurs between bulk material particles. It characterizes the flow resistance characteristics within the bulk material and is also used for overall flow internal shear stability verification, providing auxiliary basis for selecting the upper limit of the unloading zone shrinkage rate. The dynamic wall friction angle refers to the critical shear angle when relative sliding occurs between the bulk material and the wall material of the unloading zone. It characterizes the contact resistance characteristics between the bulk material and the wall, and is denoted by the symbol... express.

[0062] This step involves data acquisition through high-temperature bulk material shear tests: At least five temperature gradients are set up for the test conditions, uniformly covering the entire temperature range of the high-temperature bulk material from the feed temperature to the discharge temperature, ensuring the accuracy of the fitted curve. The dynamic internal friction angle and dynamic wall friction angle of the high-temperature bulk material are measured under each temperature condition. The dynamic wall friction angle-temperature correlation characteristic curve is obtained through data fitting, and the maximum dynamic wall friction angle of the high-temperature bulk material over the entire temperature range is extracted. As a conservative design basis for the structural design of the unloading area, the test used a sample plate with the same material as the actual device wall to ensure that the measured wall friction angle matches the actual engineering.

[0063] Furthermore, multiple temperature gradients are selected at equal intervals across the entire temperature range from feed temperature to discharge temperature, with the temperature difference between adjacent gradients not exceeding 25% of the entire temperature range. At least three parallel samples are prepared for each temperature gradient, and each sample is tested at least three times. The arithmetic mean is taken as the result of the dynamic friction angle measurement at that temperature. The dynamic internal friction angle and dynamic wall friction angle are tested in accordance with the "Standard for Shear Test Method of Bulk Materials" or equivalent industrial standards. A sample plate with the same material as the wall of the actual device is used, and the shear rate is kept constant at 1 mm / min. After the measurement is completed, the least squares method is used to perform polynomial fitting on the dynamic wall friction angle data at each temperature to obtain the dynamic wall friction angle-temperature correlation characteristic curve.

[0064] S2. Based on the characteristic data, the flow matching design of the unloading zone of the cooling device is carried out. The flow cross-sectional area of ​​the unloading zone is configured along the vertical height in a form with a constant relative shrinkage rate of cross-sectional area. This ensures that the wall constraint half-apex angle at any height within the unloading zone is less than or equal to 90° minus the maximum dynamic wall friction angle of the high-temperature bulk material throughout the entire temperature range, thus constraining the bulk material to form a piston-like integral flow.

[0065] Specifically, the wall constraint half-apex angle refers to the angle between the generatrix of the wall and the vertical direction within the axial section of the unloading zone, denoted by the symbol... This indicates that its size directly determines the flow resistance of the bulk material along the wall.

[0066] According to the principle of differential equations, when the relative decay rate per unit height of the flow cross-sectional area along the vertical height remains constant, the curve of this cross-sectional area change is uniquely determined to be an exponential function. Based on this, this embodiment adopts an exponential curve as the law of cross-sectional area change in the unloading zone. The specific form and parameter meanings are as follows:

[0067] In this embodiment, the variation of the flow cross-sectional area of ​​the unloading zone along the vertical height adopts an exponential curve form, satisfying the following relationship:

[0068]

[0069] In the formula, This refers to the cross-sectional area of ​​the flow passage at the corresponding height of the unloading zone. The coordinates represent the height of the unloading area, with the origin at the intersection of the top surface of the unloading area and the cooling section, and the vertical downward direction as the positive direction. This is the initial flow cross-sectional area at the top surface of the unloading zone; The relative shrinkage rate of the cross-sectional area is a constant negative value with dimensions in meters. -1 This characterizes the relative attenuation rate of the flow cross-sectional area per unit height, with its absolute value constantly controlled between 0.05 and 0.15 m. -1 Interval.

[0070] Compared to traditional linear conical discharge hoppers with a constant semi-apex angle, this exponential curve structure has a constant relative shrinkage rate of cross-sectional area throughout the entire process. The wall constraint semi-apex angle is adaptively adjusted with the cross-sectional shrinkage, which can accurately match the boundary conditions of bulk material flow within the entire height range. This avoids the defects of uneven flow constraints in the upper and lower sections of linear conical hoppers and the easy occurrence of local material stagnation. The cross-sectional velocity uniformity of the piston-type overall flow is also better.

[0071] By calibrating parameters The value of makes the wall constraint half-apex angle at any height position within the unloading zone. All meet the quantitative constraints:

[0072]

[0073] This constraint is based on Jannik's overall flow theory of bulk material flow. When the half-apex angle of the wall constraint is less than the complementary angle of the wall friction angle, the bulk material at the wall can continue to flow downward, avoiding material stagnation at the wall.

[0074] It should be noted that Jernike's overall flow theory is based on gravity unloading. This scheme uses forced discharge, but forced discharge only provides auxiliary downward driving force; the main flow of bulk materials is still dominated by gravity. The role of forced discharge is to actively compensate for the flow kinetic energy lost by wall friction in the contraction section, making the overall velocity distribution more uniform, rather than changing the main driving force mechanism of the bulk materials. Theoretical analysis and discrete element simulation both show that when the downward drag force generated by forced discharge does not exceed 15% of the bulk material's self-weight stress, the stress boundary conditions at the wall are basically equivalent to those under gravity unloading conditions, and Jernike's overall flow criterion can still effectively predict the risk of material stagnation at the wall. In this scheme, the control range of the discharge velocity is designed to ensure that the forced discharge drag force is always less than 10% of the bulk material's self-weight stress; therefore, this criterion applies.

[0075] Top surface of the unloading area =0, bottom surface Substituting =L into the formula The cross-sectional area of ​​the unloading area inlet is obtained. , Dividing the two equations, we get ,because The value is negative; to facilitate intuitive reading of shrinkage strength in engineering, it is defined as... The absolute value of the shrinkage rate is obtained by equivalent deformation. The final calculation result remains completely unchanged;

[0076] The ratio of the outlet cross-sectional area to the inlet cross-sectional area of ​​the unloading area. The quantitative mapping relationship is determined based on the ratio of the maximum to the minimum dynamic wall friction angle across the entire temperature range of high-temperature bulk materials.

[0077]

[0078] In the formula, This represents the minimum dynamic wall friction angle for high-temperature bulk materials across the entire temperature range. This is a structural correction factor, with a value ranging from 0.6 to 0.8. The overall value range is 0.3 to 0.6;

[0079] In industrial applications, the effective vertical height of the unloading area is typically taken as 3~8m. The value range is 0.05~0.15m -1 Substituting into the formula, we get The theoretical range is 0.301 to 0.861. In engineering applications, to balance overall flow stability and smooth discharge, the engineering range is limited to 0.3 to 0.6: when the area ratio is greater than 0.6, the shrinkage strength of the discharge zone is insufficient, and a stagnant material layer is easily formed on the wall, which cannot guarantee the overall flow pattern; when the area ratio is less than 0.3, the excessive shrinkage can easily cause discharge congestion. Therefore, 0.3 to 0.6 is ultimately the preferred range for engineering applications.

[0080] The above mapping relationship is established based on the following: According to Jannick's overall flow theory, the maximum allowable half-apex angle of the wall is directly related to the wall friction angle, the overall shrinkage of the unloading zone is positively correlated with the friction angle ratio, and the structural correction coefficient... This is used to adapt to different cylinder diameters, cross-sectional shapes, and other engineering factors, ensuring that the design results fall within the optimal engineering range. Taking a typical sintered mineral material as an example, it covers the entire temperature range. =35° =25°, the friction angle ratio is approximately 0.714, take When =0.7, the corresponding ≈0.5, falling within the optimal engineering range of 0.3~0.6. The value range of 0.6 to 0.8 is determined accordingly to ensure that materials with different frictional properties can obtain a suitable area ratio through this correction.

[0081] S3. Construct a multi-parameter collaborative constraint system, establish the matching relationship between the average flow velocity of bulk material at the unloading zone outlet and the contraction characteristics of the unloading zone, and the constraint relationship between the cooling air and bulk material water equivalent ratio and the overall flow stability. Set a dimensionless overall flow stability criterion function and the corresponding threshold interval.

[0082] Specifically, this step constructs a constraint system from two dimensions: flow characteristics and heat transfer characteristics, to achieve coordinated control of flow regime and cooling effect. The core of the overall flow stability criterion is the criterion function. :

[0083] Define the shrinkage characteristic parameters of the unloading zone ,in, The cross-sectional area of ​​the unloading area outlet is [area value missing]. This refers to the cross-sectional area of ​​the unloading area's inlet flow passage. To determine the effective vertical height of the unloading zone, a velocity matching rule is established: the average velocity of the bulk material at the outlet section of the unloading zone. With shrinkage characteristic parameters There is a positive correlation, that is, the more drastic the contraction in the unloading zone ( The smaller the value, the lower the outlet bulk material velocity, which avoids excessively high velocity causing flow disturbance and ensures flow stability;

[0084] Define the equivalent ratio parameter of cooling air to bulk water. ;in, This represents the total mass flow rate of the cooling air. For the quality handling capacity of high-temperature bulk materials, The specific heat capacity of the cooling air at constant pressure. For the specific heat capacity of high-temperature bulk materials at constant pressure, The value range is controlled between 1.0 and 1.3. This range is determined based on the optimal efficiency range of counter-current gas-solid heat exchange, which ensures that the bulk material cooling meets the standard while avoiding excessive air volume that causes flow disturbance and energy waste.

[0085] To address the issue of inconsistent dimensions among different physical quantities preventing direct weighting, a baseline discharge velocity under rated operating conditions is introduced. Compared with the benchmark shrinkage characteristic parameters The flow parameters are normalized to be dimensionless, and a dimensionless global flow stability criterion function is constructed. ,in , For preset weighting coefficients, The value range is 0.4 to 0.6. The value range is 0.4 to 0.6, and + =1, where, This comprehensive characteristic represents the flow intensity per unit unloading height. A higher value indicates a stronger coupling effect between the inertia and contraction of the bulk material flow, and a greater risk of flow disturbance. It is also related to the water equivalent ratio. The physical properties that characterize the degree of gas-solid heat transfer disturbance are matched, so a unified criterion can be constructed through linear weighting;

[0086] Furthermore, , The value is determined based on the weighting principle of flow-dominant and heat-dominant factors, and is obtained by comparing the flow regime observation data of multiple operating conditions in the cold-state overall flow calibration test with the corresponding values. value, Regression analysis was performed on the values, using the overall flow stability boundary as a constraint, to determine... and The preferred ratio range is 0.4~0.6. When the particle size of the bulk material is large (>30mm) or the wall friction angle is high, the influence of flow factors on the overall flow stability increases. It is advisable to take the upper limit of 0.6. The lower limit value is set to 0.4; when the particle size of the bulk material is small (<15mm) or the air permeability is poor, the weight of the influence of heat transfer factors on temperature uniformity increases. It is advisable to take the upper limit of 0.6. Take the lower limit value of 0.4; under normal operating conditions, take... = =0.5.

[0087] The overall flow stability criterion function given in this embodiment is a preferred form. Those skilled in the art can construct other equivalent dimensionless criterion structures based on the same flow-thermal coupling stability evaluation principle, all of which fall within the protection scope of this invention.

[0088] Set the overall flow compliance threshold range as follows ,in , The cold-state bulk flow calibration test of the target bulk material was determined. The specific steps of the cold-state calibration test are as follows:

[0089] Construct a cold-state test bench that is geometrically similar to the industrial equipment, with a geometric similarity ratio of not less than 1:10. The structure of the unloading area is made according to an exponential curve scale-down, and the wall material is the same as that of the industrial equipment.

[0090] The target bulk material with the same particle size distribution as the industrial equipment is loaded, the bulk material temperature is reduced to room temperature, and the material layer height corresponds to the height of the cooling section of the industrial equipment according to a geometric similarity ratio.

[0091] Set up no fewer than 10 sets of combined operating conditions with different discharge speeds and cooling air volumes, with the discharge speed covering 50% to 150% of the rated discharge speed of the industrial equipment and the air volume covering 60% to 140% of the rated air volume;

[0092] Under various working conditions, the flow pattern of bulk material is observed through the transparent observation window of the test bench or by the built-in tracer particle method. The velocity distribution of the material layer section is recorded simultaneously. The overall flow stability is determined by the relative standard deviation of the flow velocity of the whole section being less than 15% and the absence of a stagnant material layer on the wall.

[0093] Calculate the overall flow stability criterion function for each set of operating conditions. The value is used to stabilize the overall flow condition. The maximum value is used as Minimum value as ;

[0094] Cold calibration results , The threshold is directly applicable to high-temperature conditions because: the impact of the bulk material friction angle on the overall flow boundary conditions as temperature increases has been pre-counted by the conservative design of the unloading zone based on the maximum wall friction angle across the entire temperature range; and the magnitude of the impact of high-temperature-induced particle adhesion changes on the critical threshold for flow instability has been verified by gradient high-temperature shear tests to be less than 10%, which is within the acceptable range for engineering applications. If significant softening or adhesion of particles occurs under high-temperature conditions, calibration tests can be re-conducted under high-temperature operating conditions using the device's online temperature monitoring system to update the threshold. , Threshold.

[0095] Meanwhile, the matching relationship between the average flow velocity v of the bulk material at the outlet section of the unloading zone and the contraction characteristic parameter C must satisfy the low-disturbance flow condition where the bulk material flow Froude number Fr < 0.1. The bulk material flow Froude number is calculated by the following formula:

[0096]

[0097] in, Let g be the average velocity of the bulk material at the outlet section of the unloading zone, and g be the acceleration due to gravity. The equivalent diameter of the outlet section of the unloading zone is denoted by Froude number, which characterizes the ratio of inertial force to gravity in bulk material flow. When it is less than 0.1, the flow is dominated by gravity, and inertial disturbances can be ignored. It is the fluid dynamics basis for overall flow stability.

[0098] S4. Perform forced discharge operation at the discharge port at the bottom of the unloading area, and actively and quantitatively control the discharge rate of bulk materials.

[0099] Specifically, the forced discharge operation is achieved using a variable frequency drive mechanism. This mechanism applies a continuous and controllable mechanical thrust to the high-temperature bulk material flowing from the discharge port via frequency conversion. By adjusting the average flow velocity of the bulk material at the discharge zone outlet section, it replaces traditional gravity discharge, enabling proactive, quantitative, and precise control of the discharge speed. When multiple discharge ports are located at the bottom of the discharge zone, each port uses an independent frequency conversion drive, allowing for individual adjustment of its discharge speed and achieving differential operation.

[0100] The core function of forced discharge is to overcome the uncontrollable flow rate defect of natural discharge. By actively matching the contraction characteristics of the discharge zone, the bulk material flows downward in a uniform piston-like manner, avoiding the funnel flow defect that is prone to occur during natural discharge, where the center flow velocity is fast and the side wall flow velocity is slow.

[0101] S5. Collect temperature data from multiple spatial locations within the cooling device in a layered manner to construct multi-dimensional temperature distribution characteristics.

[0102] Specifically, temperature data is collected using a layered circumferential sampling method: at least three temperature measurement layers are arranged vertically along the cooling device, covering the upper, middle, and lower parts of the cooling zone; each temperature measurement layer has at least four temperature measurement points evenly distributed along the circumference of the cylindrical cross-section, and each temperature measurement layer is matched with an independent height-zoned air chamber. Temperature data for the entire area is obtained through simultaneous temperature measurement at multiple heights and circumferential points. The more temperature measurement layers there are, the higher the accuracy of the standard deviation of the inter-layer temperature difference in characterizing the uniformity of cooling in the vertical direction. Industrial devices can appropriately increase the number of temperature measurement layers according to the height of the cooling section to improve the accuracy of the assessment.

[0103] Temperature data is continuously collected at fixed time intervals, and the temperature values ​​and corresponding collection times at each point are recorded synchronously. Finally, a three-dimensional temperature distribution feature including height, circumferential, and time dimensions is constructed to provide full-domain data support for flow regime assessment.

[0104] S6. Based on multi-dimensional temperature distribution characteristics and combined with overall flow stability criteria, quantitatively assess the overall flow state of bulk materials.

[0105] Specifically, the overall flow status is executed using the logic of "interference verification - dual-dimensional joint evaluation":

[0106] First, conduct an operational interference check: Before determining the deterioration of the flow pattern, check whether the feed temperature, the uniformity of the top material distribution, and the air pressure of each layer of air chamber are within the normal operating range. Eliminate temperature anomalies caused by non-flow factors such as material distribution deviation, air chamber blockage, and feed temperature fluctuation to avoid accidental triggering of adjustments.

[0107] After eliminating interference, the flow regime is evaluated using two indicators:

[0108] 1. Temperature distribution characteristics assessment: Calculate two statistical indicators respectively.

[0109] Intralayer temperature standard deviation The standard deviation of the temperature at all temperature measurement points within the same temperature measurement layer characterizes the temperature uniformity of the cross section at the same height.

[0110] Standard deviation of interlayer temperature difference The standard deviation of the average temperature difference between two adjacent temperature measurement layers characterizes the cooling uniformity in the vertical direction.

[0111] When the intralayer temperature standard deviation of any layer >25℃, or standard deviation of interlayer temperature difference At temperatures above 30℃, an abnormal flow pattern of funnel flow, including tubular flow, is determined within the device, indicating a deterioration in the overall flow state. Tubular flow represents an extreme subdivision of funnel flow, and both exhibit localized temperature anomalies, allowing for a unified judgment logic. The aforementioned thresholds are based on statistical calibration using over 100 sets of field data from vertical cooling systems for industrial sintered ore, corresponding to the critical state of flow transitioning from overall flow to funnel flow.

[0112] 2. Criterion function evaluation: Calculate the value of the overall flow stability criterion function F under the current operating conditions in real time, and determine whether it falls within the preset threshold range.

[0113] When both indicators meet the requirements, the overall flow is determined to be in a stable state. If either indicator fails to meet the requirements, the overall flow state is determined to be deteriorated, triggering adaptive adjustment.

[0114] S7. Based on the evaluation results, adaptively adjust the forced discharge speed and stratified cooling air volume to maintain the overall flow stability criterion function within the preset threshold range, forming a self-feedback closed-loop control of the overall flow condition.

[0115] Specifically, the adaptive adjustment employs a scenario-specific precise control strategy, combined with hysteresis control logic to avoid frequent adjustments. Overall, it follows a priority principle of discharge speed as the primary factor and airflow as a secondary factor: discharge speed has a dominant effect on flow regulation, while airflow adjustment primarily compensates for cooling capacity. Each adjustment first modulates the discharge speed, then fine-tunes the airflow to avoid simultaneous large changes in both parameters that could cause reverse oscillations in the criteria, ensuring stable closed-loop convergence. The specific rules are as follows:

[0116] When the standard deviation of the temperature within a single temperature-measuring layer exceeds the standard: Firstly, reduce the forced discharge speed at the discharge port in steps of 5% to 10% of the rated discharge speed. Simultaneously, increase the cooling airflow of the corresponding height zone air chamber of that temperature-measuring layer in steps of 5% to 8% of the rated airflow of the corresponding area. The adjustment step size is determined based on process control tuning principles: too small a step size will lead to a delayed flow correction response, failing to promptly suppress the development of flow deviation; too large a step size will disturb the material layer due to sudden changes in airflow and velocity, thus disrupting the overall flow stability. Airflow is more sensitive to disturbances in the material layer flow than discharge speed; therefore, the airflow adjustment step size is slightly smaller than the discharge speed step size to ensure flow stability during adjustment.

[0117] When the temperature deviation is concentrated on one side of the cross-section (the difference between the highest and lowest temperatures at the circumferential temperature measurement points within the same temperature measurement layer exceeds 30℃, and the high-temperature area continuously covers one-quarter or more of the circumferential cross-sectional area of ​​the layer, while the low-temperature area is located on the opposite side), a differential speed operation mode is formed by controlling the symmetrical discharge ports on both sides. The discharge speed on the side with the higher temperature is increased by 10% to 30% compared to the other side, breaking the skewed funnel flow channel through offset discharge. This differential speed ratio range is determined based on discrete element simulation of the bulk material flow in the unloading area of ​​the vertical cooling device. The simulation model is established using EDEM software, the bulk particles are generated according to the actual particle size distribution, the wall contact parameters are set based on the measured dynamic wall friction angle, and the discharge port adopts independent velocity boundary conditions. Simulation results show that when the differential velocity ratio is below 10%, the flow deviation channel cannot be effectively broken, and the improvement rate of cross-sectional velocity non-uniformity is less than 5%; when the differential velocity ratio is above 30%, it is easy to induce reverse flow deviation on the other side, forming a new funnel flow channel; when the differential velocity ratio is 10%~30%, the improvement rate of cross-sectional velocity non-uniformity reaches 15%~35%, and there is no risk of reverse flow deviation. This ratio range has also been verified and confirmed by an industrial-scale cold-state test bench.

[0118] When the standard deviation of interlayer temperature difference exceeds the standard: prioritize reducing the overall forced discharge speed, extend the cooling residence time of bulk materials, and simultaneously increase the total cooling air volume according to the water equivalent ratio matching principle to maintain the water equivalent ratio in the optimal range of 1.0~1.3 and enhance the overall heat exchange intensity.

[0119] The adjustment process is carried out step by step according to the preset step size. After each adjustment is completed, the system is allowed to stabilize before the flow state is reassessed. The adjustment continues until the standard deviation of the intralayer temperature is ≤20℃ and the standard deviation of the interlayer temperature difference is ≤25℃. After the criterion function returns to the preset threshold range, the current operating parameters are maintained.

[0120] The hysteresis design, with a recovery threshold stricter than the degradation trigger threshold, avoids frequent fluctuations in the flow regime near critical states, ensuring operational stability. Through the complete process described above—real-time acquisition, disturbance verification, state assessment, and dynamic adjustment—a self-feedback closed-loop control of the overall flow conditions is ultimately formed.

[0121] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A material discharge method for a vertical cooling device based on overall flow, characterized in that, Includes the following steps: Data on the dynamic friction angle characteristics of high-temperature bulk materials during the entire cooling temperature range were collected to obtain the dynamic internal friction angle and dynamic wall friction angle at different temperatures. Based on the aforementioned characteristic data, the flow matching design of the unloading area of ​​the cooling device is carried out. The flow cross-sectional area of ​​the unloading area is configured along the vertical height in a form with a constant relative shrinkage rate of the cross-sectional area. This ensures that the wall constraint half-apex angle at any height in the unloading area is less than or equal to 90° minus the maximum dynamic wall friction angle of the high-temperature bulk material throughout the entire temperature range, thereby constraining the bulk material to form a piston-like integral flow. A multi-parameter collaborative constraint system was constructed to establish the matching relationship between the average flow velocity of bulk material at the outlet of the unloading zone and the contraction characteristics of the unloading zone, as well as the constraint relationship between the cooling air and bulk material water equivalent ratio and the overall flow stability. A dimensionless overall flow stability criterion function and the corresponding threshold range were set. Variable frequency forced discharge is performed at the discharge port at the bottom of the unloading area to actively and quantitatively control the discharge rate of bulk materials; Temperature data from multiple spatial locations within the cooling device are collected in layers to construct multi-dimensional temperature distribution characteristics. Based on the aforementioned multi-dimensional temperature distribution characteristics, the overall flow state of bulk materials is quantitatively evaluated using the overall flow stability criterion function. Based on the evaluation results, the forced discharge speed and stratified cooling air volume are adaptively adjusted to keep the overall flow stability criterion function within the preset threshold range, thus forming a self-feedback closed-loop control of the overall flow condition.

2. The material discharge method for a vertical cooling device based on overall flow according to claim 1, characterized in that, The variation of the flow cross-sectional area of ​​the unloading zone along the vertical height follows an exponential curve pattern, satisfying the following relationship: In the formula, This refers to the cross-sectional area of ​​the flow passage at the corresponding height of the unloading zone. The coordinates represent the height of the unloading area, with the origin at the intersection of the top surface of the unloading area and the cooling section, and the vertical downward direction as the positive direction. This is the initial flow cross-sectional area at the top surface of the unloading zone; The relative shrinkage rate of the cross-sectional area is a constant negative value with dimensions in meters. -1 , characterizing the relative decay rate of the flow cross-sectional area per unit height; The wall constraint half-apex angle is the angle between the generatrix of the inner wall surface of the axial section of the unloading area and the vertical direction, determined by calibration parameters. The numerical matching of the wall constraint half-apex angle size.

3. The material discharge method for a vertical cooling device based on overall flow according to claim 2, characterized in that, The acquisition of dynamic friction angle characteristic data specifically includes: setting up test conditions with no less than 5 temperature gradients to cover the entire temperature range of high-temperature bulk materials from feed temperature to discharge temperature, measuring the dynamic internal friction angle and dynamic wall friction angle of high-temperature bulk materials at each temperature, and fitting the dynamic wall friction angle-temperature correlation characteristic curve. The wall-constrained half-apex angle Quantitative constraints must be met: ,in, This represents the maximum dynamic wall friction angle of high-temperature bulk materials across the entire temperature range.

4. The material discharge method for a vertical cooling device based on overall flow according to claim 1, characterized in that, The construction of the multi-parameter collaborative constraint system specifically includes: Define the shrinkage characteristic parameters of the unloading zone ,in, The cross-sectional area of ​​the unloading area outlet is [area value missing]. This refers to the cross-sectional area of ​​the unloading area's inlet flow passage. This refers to the effective vertical height of the unloading area; Establish rate matching rules: average flow velocity of bulk material at the outlet section of the unloading zone. With shrinkage characteristic parameters There is a positive correlation, that is, the shrinkage characteristic parameter The smaller the size, the more drastic the contraction of the unloading zone, corresponding to the allowable average flow velocity of the bulk material. The lower; Define the equivalent ratio parameter of cooling air to bulk water. ,in, This represents the total mass flow rate of the cooling air. For the quality handling capacity of high-temperature bulk materials, The specific heat capacity of the cooling air at constant pressure. The specific heat capacity at constant pressure for high-temperature bulk materials; Introducing the reference discharge flow rate under rated operating conditions Compared with the benchmark shrinkage characteristic parameters Construct a dimensionless global flow stability criterion function ,in , For preset weighting coefficients, The value range is 0.4 to 0.

6. The value range is 0.4 to 0.6, and + =1; Set the overall flow compliance threshold range as ,in , Determined by cold-state bulk material integral flow calibration test.

5. The material discharge method for a vertical cooling device based on overall flow according to claim 4, characterized in that, The threshold range of the overall flow stability criterion satisfies a quantitative constraint: the ratio of cooling air to bulk water equivalents. The value range is 1.0~1.3, which represents the average velocity of the bulk material at the outlet section of the unloading area. With shrinkage characteristic parameters The matching relationship satisfies the Froude number of bulk material flow. ; The Froude number for bulk material flow is calculated using the following formula: in, Let g be the average velocity of the bulk material at the outlet section of the unloading zone, and g be the acceleration due to gravity. The equivalent diameter of the outlet section of the unloading zone; When the overall flow state is determined to be deteriorated, or the overall flow stability criterion function is used... When the flow deviates from the preset threshold range, the forced discharge speed is reduced in increments of 5% to 10% of the rated discharge speed to correct the flow state. Simultaneously, the cooling airflow in the corresponding height area is increased in increments of 5% to 8% of the rated airflow in the corresponding height area, until the criterion function is reached. Regression to the preset threshold range.

6. The material discharge method for a vertical cooling device based on overall flow according to claim 1, characterized in that, The temperature data is collected by: at least three temperature measuring layers are arranged in the vertical height direction of the cooling device, and at least four temperature measuring points are evenly arranged in the circumferential direction of each temperature measuring layer. Each temperature measuring layer is matched with the corresponding height zone air chamber. The temperature data of the whole area is obtained by synchronously measuring the temperature at multiple height and multiple circumferential points. The quantitative assessment of the overall flow state of bulk materials specifically includes: Before determining the deterioration of the flow state, first check whether the feed temperature, the uniformity of the top material distribution, and the air pressure of each layer of air chamber are within the normal operating range, and eliminate temperature abnormalities caused by non-flow factors such as material distribution deviation, air chamber blockage, and feed temperature fluctuation. Calculate the intra-layer temperature standard deviation of all temperature measurement points within the same temperature measurement layer. ; Calculate the standard deviation of the interlayer temperature difference of the average temperature difference between two adjacent temperature measurement layers. ; When the intralayer temperature standard deviation of any layer >25℃, or standard deviation of interlayer temperature difference When the temperature is above 30℃, an abnormal flow state of funnel flow, including tubular flow, is formed inside the device, and the overall flow state deteriorates.

7. The material discharge method for a vertical cooling device based on overall flow according to claim 6, characterized in that, When the overall flow state is determined to be deteriorated, the adaptive adjustment specifically includes: When the standard deviation of the temperature within a single temperature measuring layer exceeds the standard, the forced discharge speed of the discharge port is reduced and the cooling air volume of the corresponding height area of ​​the temperature measuring layer is increased; when at least two symmetrical discharge ports are set at the bottom of the unloading area and the temperature deviation is concentrated on one side of the cross section, the discharge ports are controlled to form a differential speed operation mode, and the discharge speed on the side with higher temperature is increased by 10% to 30% compared with the other side, breaking the skewed funnel flow channel. When the standard deviation of the interlayer temperature difference exceeds the standard, the overall forced discharge speed should be reduced first, the bulk material cooling residence time should be extended, and the total cooling air volume should be increased simultaneously according to the water equivalent ratio matching principle. Continue adjusting until the standard deviation of intralayer temperature is ≤20℃ and the standard deviation of interlayer temperature difference is ≤25℃, to maintain stable operating parameters.

8. The material discharge method for a vertical cooling device based on overall flow according to claim 1, characterized in that, The forced discharge operation specifically adopts a discharge drive mechanism with variable frequency control. The high-temperature bulk material flowing out of the discharge port is applied with a continuous and controllable mechanical thrust through the variable frequency drive. The discharge speed is quantitatively controlled by adjusting the average flow velocity of the bulk material at the outlet section of the unloading zone. When multiple discharge ports are set, each discharge port adopts an independent variable frequency drive to achieve differential speed operation.

9. The material discharge method for a vertical cooling device based on overall flow according to claim 1, characterized in that, The high-temperature bulk material is metallurgical sintered ore or pellet granules with a particle size range of 5~50mm.

10. The material discharge method for a vertical cooling device based on overall flow according to claim 2, characterized in that, The relative shrinkage rate of the cross-sectional area The absolute value is controlled between 0.05 and 0.15m. -1 Within the unloading zone, the outlet cross-sectional area and the inlet cross-sectional area satisfy a quantitative matching relationship: In the formula, This represents the minimum dynamic wall friction angle for high-temperature bulk materials across the entire temperature range. This is a structural correction factor, with a value ranging from 0.6 to 0.

8. The overall value range is 0.3 to 0.6.

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