Coal mill grinding collaborative control method and system based on dynamic air volume regulation

Abstract

The application discloses a coal mill grinding collaborative control method and system based on dynamic air volume regulation, and belongs to the field of coal mills. The method comprises the following steps: collecting the operation parameters of the coal mill, extracting the cumulative operation time length of the grinding part and the actual time interval value of the grinding part, and calculating the wear stage quantitative factor; correcting the preset basic grindability parameters and the basic grinding area parameters to obtain the corrected grindability parameters and the corrected grinding area parameters, calculating the adaptive load force set value and the adaptive air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state, and calculating the dynamic primary air volume set value; generating and issuing the initial air volume regulation instruction and the initial load force regulation instruction according to the dynamic primary air volume set value and the adaptive load force set value, so that the temperature is maintained within the preset target temperature interval. The application solves the technical problems that the existing coal mill cannot dynamically adapt to the interference of the wear attenuation of the grinding part and is prone to cause the running safety risk of mill blocking.

Description

Technical Field

[0001] This invention relates to the field of coal mill technology, and specifically to a coal mill pulverizing collaborative control method and system based on dynamic air volume regulation. Background Technology

[0002] In the field of operation and control of medium-speed coal mill pulverizing systems in thermal power plants, the industry currently generally adopts a fixed air-coal ratio and fixed loading force control strategy based on the new operating conditions of the grinding components. The control parameters do not incorporate the wear and decay characteristics of the grinding components throughout their entire life cycle for dynamic adaptation. As the grinding roller sleeves and grinding disc liners continue to wear during long-term grinding operations, the effective grinding working surface is continuously reduced, and the grinding cutting efficiency continues to decline. Under the fixed parameter mode, problems such as excessive fluctuations in coal powder fineness, poor coal powder uniformity, and continuous increase in pulverizing power consumption will gradually emerge. At the same time, in the traditional control logic, the coal mill outlet temperature regulation and the primary air total flow control are coupled. The temperature regulation process will synchronously change the total air volume, disturbing the stable state of the air-coal flow field inside the mill. This can easily lead to operational safety risks such as mill blockage, and it is also impossible to simultaneously ensure coal powder quality, operational economy, and system stability throughout the entire wear cycle of the grinding components. Summary of the Invention

[0003] This application provides a coal mill pulverizing collaborative control method and system based on dynamic air volume adjustment, which aims to solve the technical problem that existing coal mills cannot dynamically adapt to the interference of wear and decay of grinding parts, which easily leads to operational safety risks such as mill blockage.

[0004] In view of the above problems, this application provides a method and system for coordinated control of coal mill pulverization based on dynamic air volume regulation.

[0005] The first aspect disclosed in this application provides a method for coordinated control of coal mill pulverization based on dynamic airflow regulation, the method comprising: The system collects the operating parameters of the coal mill, extracts the cumulative running time of the grinding components and the real-time gap value of the grinding components, and calculates the wear stage quantification factor based on the cumulative running time and real-time gap value of the grinding components. Based on the wear stage quantification factor, the preset basic grindability parameters and basic grinding area parameters are corrected to obtain the corrected grindability parameters and corrected grinding area parameters. Based on the corrected grindability parameters and the corrected grinding area parameters, combined with the current coal feed rate, the system calculates the appropriate loading force setting value and the appropriate air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state. Based on the appropriate air-coal ratio coefficient and the current coal feed rate, the system calculates the dynamic primary air volume setting value. Based on the dynamic primary air volume setting value and the appropriate loading force setting value, the system generates and issues initial air volume adjustment commands and initial loading force adjustment commands to maintain the coal mill outlet temperature within the preset target temperature range.

[0006] Another aspect of this application discloses a coal mill pulverizing collaborative control system based on dynamic airflow regulation, the system comprising: The system comprises the following modules: a data acquisition module for collecting pulverizer operating parameters, extracting the cumulative running time and real-time gap value of the grinding components, and calculating a wear stage quantification factor based on these parameters; a correction module for correcting preset basic grindability parameters and basic grinding area parameters based on the wear stage quantification factor, resulting in corrected grindability parameters and corrected grinding area parameters; a calculation module for calculating, based on the corrected grindability parameters, the corrected grinding area parameters, and the current coal feed rate, the appropriate loading force setting value and the appropriate air-coal ratio coefficient required to maintain the target pulverized coal fineness under the current wear state; a dynamic module for calculating the dynamic primary air volume setting value based on the appropriate air-coal ratio coefficient and the current coal feed rate; and an execution module for generating and issuing initial air volume adjustment commands and initial loading force adjustment commands based on the dynamic primary air volume setting value and the appropriate loading force setting value, thereby maintaining the pulverizer outlet temperature within the preset target temperature range.

[0007] One or more technical solutions provided in this application have at least the following technical effects or advantages: By collecting the cumulative running time and real-time gap value of the grinding components, the wear stage quantification factor is calculated. This dynamically corrects the basic grindability parameters and basic grinding area parameters. The loading force setpoint and dynamic primary air volume setpoint are calculated in conjunction with the calculation to adapt to the current wear state. The outlet temperature is independently controlled by the cold and hot air ratio method with the total air volume locked. Combined with differential pressure feedback, the air volume is dynamically compensated. Ultimately, the target coal powder fineness and uniformity can be stably maintained throughout the entire wear cycle of the grinding components, reducing the overall power consumption of the pulverizing system, eliminating the coupling interference of temperature regulation on the total air volume, effectively preventing the risk of mill blockage, and achieving efficient, stable, and safe operation of the pulverizing system throughout its entire life cycle.

[0008] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0009] Figure 1 A flowchart illustrating the collaborative control method for coal mill pulverization based on dynamic airflow regulation is provided for embodiments of this application. Figure 2 A schematic diagram of the structure of a coal mill pulverizing collaborative control system based on dynamic air volume adjustment is provided for the embodiments of this application.

[0010] Explanation of reference numerals in the attached diagram: Acquisition module 11, Correction module 12, Calculation module 13, Dynamic module 14, Execution module 15. Detailed Implementation

[0011] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0012] The overall concept of the technical solution provided in this application is as follows: This application provides a method and system for coordinated control of coal mill pulverization based on dynamic airflow regulation. The wear stage quantification factor is calculated by using the cumulative running time of the grinding elements and the real-time gap value. This dynamically corrects the grindability and grinding area benchmark parameters, and coordinates the calculation of the adaptive loading force setpoint and dynamic primary airflow setpoint. The outlet temperature is independently controlled using a total volume-locked hot and cold air ratio method, supplemented by a differential pressure feedback dynamic airflow compensation mechanism. Ultimately, this method can stabilize the fineness and uniformity of coal powder throughout the entire wear cycle of the grinding elements, reduce the overall power consumption of the pulverizing system, eliminate interference from airflow and temperature regulation, avoid the risk of mill blockage, and achieve efficient, stable, and economical operation of the pulverizing system throughout its entire lifecycle.

[0013] After introducing the basic principles of this application, various non-limiting embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0014] Example 1, as Figure 1 As shown in the embodiments of this application, a coal mill pulverizing collaborative control method based on dynamic air volume regulation is provided. The method includes: S100: Collect the operating parameters of the coal mill, extract the cumulative running time of the grinding parts and the real-time gap value of the grinding parts, and calculate the wear stage quantification factor based on the cumulative running time of the grinding parts and the real-time gap value of the grinding parts.

[0015] Specifically, firstly, by deploying sensing devices and operational data acquisition modules on the coal mill body and auxiliary systems, all operating parameters of the coal mill are collected in real time. Then, two core wear characterization parameters are extracted from the collected parameter set: the cumulative running time of the grinding components and the real-time gap value of the grinding components. The cumulative running time of the grinding components refers to the cumulative effective time of the coal mill in the state of loading and grinding since the replacement and commissioning of core grinding components such as grinding rollers and grinding disc liners. Only the working period of actual coal powder grinding is counted, and the periods of no-load standby, shutdown for maintenance, start-stop transition, etc., which do not generate effective grinding wear, are automatically excluded. It is a macroscopic characterization indicator that reflects the fatigue wear progress of the wear-resistant layer of the grinding components from the dimension of time accumulation. The real-time gap value of the grinding components refers to the real-time detection value of the working gap between the outer working surface of the grinding roller sleeve and the working surface of the grinding disc liner. This gap will continue to increase as the wear-resistant layer on the surface of the grinding components is continuously worn away. It is usually collected and fed back in real time by high-precision displacement sensors installed on the grinding roller support or hydraulic loading circuit. It is a concrete microscopic indicator that directly reflects the wear degree of the grinding components from the dimension of physical form.

[0016] After extracting the two parameters, the wear ratio is first calculated. This involves comparing the extracted cumulative running time of the grinding parts with the rated running time of the grinding parts pre-stored in the control system. The rated running time of the grinding parts is the theoretical total running time calibrated by the equipment manufacturer based on standard coal quality and rated output conditions, when the wear-resistant layer of the grinding parts wears normally from a brand new state to the scrap limit. It serves as the full-scale benchmark value for assessing the degree of wear in the time dimension. The corresponding value range of the wear ratio is 0 to 1. The closer the value is to 1, the higher the degree of wear accumulation in the time dimension.

[0017] Then, the gap wear ratio is calculated. First, the gap growth is obtained by subtracting the preset gap value of the new state of the grinding part from the real-time gap value of the grinding part. Then, the gap growth is divided by the preset limit wear gap value of the grinding part to finally obtain the gap wear ratio. The gap value of the new state of the grinding part is the initial working gap when the grinding part is newly installed and debugged and has not produced any wear. It serves as the zero point benchmark for gap wear calculation. The limit wear gap value of the grinding part is the maximum allowable increase in working gap compared to the new state when the wear layer of the grinding part is worn to the scrap threshold. It serves as the full-scale benchmark for evaluating the degree of wear in the gap dimension. The gap wear ratio is also mapped to the numerical range of 0 to 1, which can directly correspond to the relative proportion of physical wear of the grinding part.

[0018] Finally, based on the preset weighting coefficients, the proportion of time-based wear and the proportion of gap wear are weighted and summed to obtain the wear stage quantification factor. This factor is a dimensionless standardized value ranging from 0 to 1. 0 corresponds to the initial state of the grinding part when it is newly put into operation, and 1 corresponds to the scrapped state of the grinding part when it reaches the limit of wear. The larger the value, the deeper the overall wear of the grinding part. By integrating the cumulative fatigue characteristics of the time dimension and the gap wear characteristics of the physical dimension, the bias caused by a single evaluation dimension can be effectively eliminated. For example, in the scenario of long-term low-load operation, the proportion of time-based wear is high but the actual physical wear is light, or in the scenario of short-term high-load grinding of hard coal, the gap wear progresses quickly but the proportion of time-based wear is low. After the weighted fusion of the two dimensions, the true wear stage of the grinding part can be more accurately represented.

[0019] S200: Based on the wear stage quantification factor, the preset basic grindability parameters and basic grinding area parameters are corrected to obtain the corrected grindability parameters and corrected grinding area parameters.

[0020] Specifically, based on two sets of new state reference parameters pre-stored in the control system, parameter corrections are performed according to the physical attenuation law corresponding to the degree of wear. During the calculation process, the definitions of the two sets of preset reference parameters are first clarified. The preset basic grindability parameter is a benchmark process parameter calibrated for the designed coal type under the new zero-wear state of the grinding parts. It characterizes the ease with which raw coal is ground into qualified coal powder. It is usually solidified in the control logic in the form of the corresponding conversion value of the Hardgrove Grindability Index. This parameter directly determines the grinding energy input required to achieve the target coal powder fineness under the unit coal feed rate. It is the core calculation benchmark for setting the loading force and air-coal ratio under the new working condition. The preset basic grinding area parameter is the benchmark geometric area value of the effective contact grinding area between the grinding roller and the grinding disc liner under the new installation state of the grinding parts. This area directly determines the grinding range of the coal and the grinding efficiency in a single grinding process. It is the core geometric benchmark for calculating the pulverizing output capacity. Both sets of basic parameters correspond to the new grinding parts working condition where the wear stage quantification factor is 0.

[0021] During the correction, the basic grindability parameters are first attenuated and corrected according to the wear stage quantification factor to obtain the corrected grindability parameters. The attenuation correction here follows the physical law that the deeper the wear, the worse the equivalent grindability. That is, as the wear of the grinding parts intensifies, the wear-resistant layer of the grinding working surface is gradually worn away, the surface morphology tends to be smooth, the transmission efficiency of grinding shear and extrusion forces decreases, and the crushing and grinding effect on coal particles under the same loading force is weakened, which is equivalent to the worse grindability of the raw coal. Therefore, the correction calculation takes the basic grindability parameters as the base and multiplies them by the grindability attenuation coefficient obtained by mapping the wear stage quantification factor. The coefficient ranges from 0 to 1 and the coefficient is smaller as the wear is more severe. Finally, the corrected grindability parameters that fit the current wear state are obtained.

[0022] Simultaneously, the basic grinding area parameters are reduced and corrected according to the wear stage quantification factor to obtain the corrected grinding area parameters. The physical logic corresponding to this reduction and correction is that during the wear process of the grinding parts, the contact surface between the grinding roller sleeve and the grinding disc liner will undergo contour deformation due to the wear-resistant layer loss. The effective contact grinding area will continuously shrink as the wear deepens, resulting in a decrease in the amount of coal that can be processed per unit time and a reduction in pulverizing output capacity. Therefore, the correction calculation takes the basic grinding area parameters as the base and multiplies them by the grinding area reduction coefficient obtained by mapping the wear stage quantification factor. This coefficient also decreases linearly or gradually according to a preset curve as the wear stage quantification factor increases, and finally obtains the corrected grinding area parameters that match the current wear contour of the grinding parts.

[0023] S300: Based on the corrected grindability parameters and the corrected grinding area parameters, and in conjunction with the current coal feed rate, calculate the appropriate loading force setting value and the appropriate air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state.

[0024] Specifically, the system first reads three sets of input parameters: the corrected grindability parameter, the corrected grinding area parameter, and the current coal feed rate. These are then input into a pre-defined output mapping table to obtain the reference loading force value and the reference air-coal ratio value. This output mapping table is a multi-dimensional mapping data table established in advance through laboratory bench tests and on-site working condition calibration. With grindability parameter, grinding area, and coal feed rate as input dimensions, it outputs the basic reference values ​​of loading force and air-coal ratio that meet the basic grinding output requirements. Its data logic conforms to the matching law between grinding capacity and pulverizing load. The wear-corrected parameter input can directly output a basic control benchmark that adapts to the current grinding capacity, avoiding the capacity matching deviation caused by directly using the benchmark parameters of brand-new parts.

[0025] After completing the basic reference value lookup table, the process index correction calculations are carried out simultaneously in two paths. The loading force correction branch first reads the preset target pulverized coal fineness threshold. This threshold is the pulverized coal fineness control target clearly required by the boiler combustion process, usually expressed as the percentage of residue on an R90 sieve. The smaller the value, the finer the pulverized coal particle size. It is a core quality indicator for ensuring pulverized coal burnout rate, reducing fly ash carbon content, and stabilizing boiler combustion. Subsequently, the reference loading force value and the target pulverized coal fineness threshold are input into the preset loading force correction relationship table to obtain the loading force correction ratio. The loading force correction relationship table is a pre-calibrated data table reflecting the correspondence between pulverized coal fineness requirements and loading force adjustment ratios. Its internal logic is based on pulverized coal fineness... Higher requirements necessitate greater grinding pressure, and the correction ratio increases accordingly with the fineness requirements. This is used to match specific fineness quality targets based on the basic output reference value. Finally, the reference loading force value is multiplied by the loading force correction ratio to obtain the appropriate loading force setting value. This setting value is a hydraulic loading mechanism pressure setting value that perfectly matches the current wear level, coal feed load, and coal powder fineness requirements, directly determining the magnitude of the grinding and squeezing force of the grinding roller on the coal material on the grinding disc. The air-coal ratio correction branch reads the preset coal powder uniformity index threshold. The coal powder uniformity index is a process indicator that characterizes the uniformity of coal powder particle size distribution. A higher index indicates a more concentrated coal powder particle size distribution and a lower proportion of excessively coarse and excessively fine particles.

[0026] Subsequently, the reference air-coal ratio value and the coal powder uniformity index threshold are input into a preset air-coal ratio correction relationship table to obtain the air-coal ratio correction ratio. The air-coal ratio correction relationship table is a pre-calibrated data table that reflects the correspondence between coal powder uniformity requirements and air-coal ratio adjustment ratios. Its internal logic is that higher coal powder uniformity requirements require more reasonable primary air carrying and air-coal classification capabilities. By adjusting the air-coal ratio, the air-coal flow field and separation effect in the mill can be optimized, thereby improving the uniformity of coal powder particle size distribution. Finally, the reference air-coal ratio value is multiplied by the air-coal ratio correction ratio to obtain the suitable air-coal ratio coefficient.

[0027] S400: The dynamic primary air volume setting value is calculated based on the adaptive air-coal ratio coefficient and the current coal feed rate.

[0028] Specifically, the real-time sampled value of the current coal feed rate is first read, and the filtered coal feed rate is obtained after the real-time sampled value is processed by moving average filtering. The moving average filtering is achieved by successively calculating the arithmetic mean of the sampled values ​​within a fixed time window, which can effectively filter out random fluctuations and feed pulse interference caused by the instantaneous sampling of the coal feed belt scale. The current coal feed rate is the actual coal feeding rate of the coal mill per unit time, which directly reflects the current load level of the pulverizing system and is the core load benchmark for calculating the air-coal ratio.

[0029] After smoothing the coal feed rate, the adaptive air-coal ratio coefficient, which matches the current wear state of the grinding components and the uniformity requirements of the pulverized coal, is read. The adaptive air-coal ratio coefficient is multiplied by the filtered coal feed rate to calculate the theoretical primary air volume value. The adaptive air-coal ratio coefficient is different from the fixed air-coal ratio value in traditional control logic. Its value has been dynamically corrected according to the wear degree of the grinding components. The deeper the wear, the more the coefficient is adjusted to match the attenuated grinding and carrying capacity. It is the proportional benchmark connecting the wear state and the air volume setting. The theoretical primary air volume value is the ideal volumetric air volume matching the current coal feed load and wear state under standard working conditions. It is only used as the calculation basis for subsequent working condition correction and has not yet considered the influence of the actual air temperature on the air volume.

[0030] Subsequently, the current inlet air temperature of the coal mill is read. Based on the ratio of this inlet air temperature to the preset standard air temperature, density compensation is calculated for the theoretical primary air volume to obtain the compensated primary air volume. The current inlet air temperature of the coal mill is the actual temperature of the primary air entering the coal mill cavity after the hot and cold air are mixed. Since the gas volume expands and the density decreases as the temperature rises, the mass of primary air under the same volumetric flow rate will decrease as the temperature rises. However, the primary air mass flow rate is what carries coal powder and dries raw coal in the pulverizing system. Controlling the volumetric air volume alone will cause the actual air-coal mass ratio to deviate from the target due to air temperature fluctuations. Therefore, density compensation must be introduced. The preset standard air temperature is a pre-set reference value of air temperature under standard conditions, corresponding to the standard temperature of primary air under the design conditions. The density compensation calculation is based on the inverse relationship between temperature and density under ideal gas conditions. The volumetric air volume at the actual air temperature is converted into a volumetric set value that is equivalent to the standard condition and meets the mass ratio requirements. This completely eliminates the interference of inlet air temperature fluctuations on the actual air supply quality and ensures the mass matching accuracy of the air-coal ratio. Finally, the compensated primary air volume value is determined as the dynamic primary air volume setpoint. This setpoint is the primary air volume control target that fully adapts to the current wear state of the grinding parts, coal feeding load and inlet air temperature conditions. It is also the total amount constraint benchmark for the subsequent operation of the air volume adjustment mechanism and the allocation of the opening ratio of hot and cold air.

[0031] S500: Based on the dynamic primary air volume setting value and the adaptive loading force setting value, generate and issue initial air volume adjustment command and initial loading force adjustment command to maintain the coal mill outlet temperature within the preset target temperature range.

[0032] Specifically, firstly, an initial air volume adjustment command is generated based on the dynamic primary air volume setpoint to control the opening of the primary air regulating mechanism. This initial air volume adjustment command is a basic air volume control signal obtained entirely from the feedforward calculation of the wear of the grinding mill components. It corresponds to the target opening of the primary air total regulating mechanism at the coal mill inlet and is used to precisely adjust the total primary air flow entering the coal mill to the optimal setpoint after wear adaptation. This command has not yet been superimposed with the correction compensation for the on-site operating deviation and is the benchmark command for differential pressure dynamic regulation. The primary air regulating mechanism is the execution device that controls the total primary air throughput at the coal mill inlet. It is generally an inlet total air volume regulating baffle and is responsible for implementing the total air volume control target. It is the carrier for the implementation of the air-coal ratio.

[0033] Simultaneously, an initial loading force adjustment command is generated based on the adapted loading force setting value to control the hydraulic loading mechanism. This initial loading force adjustment command is a hydraulic system pressure control signal that matches the current wear level, coal feed load, and coal powder fineness requirements. It corresponds to the target oil supply pressure of the hydraulic loading cylinder and is used to drive the grinding roller to apply a corresponding intensity of crushing pressure to the coal material on the grinding disc. This is also a basic output command of feedforward control, which can directly ensure the matching degree between the grinding capacity and the current working conditions. The hydraulic loading mechanism is the core device that provides grinding power to the medium-speed coal mill. It drives the grinding roller to apply pressure through the thrust of the hydraulic cylinder. The magnitude of the pressure directly determines the grinding intensity and is a key execution unit that affects the coal powder fineness and pulverizing power consumption.

[0034] While generating two types of basic instructions, the system uses the dynamic primary air volume setpoint as a fixed total constraint, and simultaneously calculates the opening ratio of the cold air regulating mechanism and the hot air regulating mechanism. It generates cold and hot air regulating instructions to maintain the coal mill outlet temperature and sends these instructions, along with the initial air volume regulating instructions, to the field execution terminal. The cold air regulating mechanism and the hot air regulating mechanism correspond to the cold primary air damper and the hot primary air damper at the coal mill inlet, respectively. They introduce ambient cold primary air and high-temperature hot primary air from the air preheater, respectively. After mixing, they form the working air at the coal mill inlet. By adjusting the opening ratio of the two mechanisms, the inlet mixed air temperature can be changed without changing the total air volume, thereby regulating the coal powder airflow temperature at the coal mill outlet. The preset target temperature range is a safety and performance dual constraint range pre-set by the pulverizing process. Too low a temperature will lead to excessive moisture in the coal powder, reduced fluidity, and the risk of pipe blockage. Too high a temperature will pose safety hazards such as spontaneous combustion and explosion of the coal powder. It is a core process indicator for the stable operation of the coal mill.

[0035] In specific temperature adjustment, the actual measured value of the coal mill outlet temperature is first obtained and compared with the preset target temperature range to obtain the temperature deviation value. Then, based on the polarity of the temperature deviation value, the dynamic primary air volume setting value is used as an insurmountable total boundary to adjust the opening ratio of cold air and hot air in reverse linkage. When the outlet temperature is higher than the target range, the opening ratio of cold air is increased proportionally and the opening ratio of hot air is decreased to reduce the mixed air temperature and lower the outlet temperature. When the outlet temperature is lower than the target range, the adjustment is reversed. The entire adjustment process only adjusts the opening ratio of cold and hot air, and never modifies the value of the dynamic primary air volume setting value, strictly ensuring that the total primary air flow is constant, avoiding fluctuations in total air volume caused by temperature adjustment, which would interfere with the coal powder carrying effect and the stability of the air-coal powder flow field inside the mill.

[0036] Furthermore, the method provided in this application embodiment also includes: collecting the actual differential pressure value during the operation of the coal mill, comparing the actual differential pressure value with a preset differential pressure target value to obtain a differential pressure deviation value, dynamically compensating the initial air volume adjustment command based on the differential pressure deviation value, and outputting the final primary air volume adjustment command; wherein, the dynamic compensation process does not change the opening ratio benchmark of the cold air adjustment mechanism and the hot air adjustment mechanism.

[0037] Specifically, pressure transmitters installed in the inlet air chamber and outlet pulverized coal pipeline of the coal mill are used to collect the actual differential pressure value during the operation of the coal mill in real time. The actual differential pressure value refers to the static pressure difference between the primary air side at the inlet of the coal mill and the air-pulverized coal mixing side at the outlet. This value directly reflects the comprehensive operating status of the coal bed thickness, pulverized coal concentration and ventilation resistance inside the mill. A high differential pressure usually corresponds to coal accumulation inside the mill, excessively thick coal bed, and insufficient ventilation carrying capacity, which is a precursor signal of mill blockage. A low differential pressure corresponds to insufficient coal storage in the mill and relatively excessive air volume, which can easily lead to excessively fine pulverized coal and artificially high power consumption of the primary air fan. It is the core intuitive indicator of whether the air-pulverized coal operating status inside the mill is in the optimal range.

[0038] After data collection, the system retrieves and compares the preset differential pressure target value that matches the current coal feed rate and wear stage. The preset differential pressure target value is an ideal differential pressure benchmark value obtained in advance through working condition calibration, corresponding to a moderate coal seam thickness in the mill, optimal air-coal carrying efficiency, and stable coal powder fineness. This value will be dynamically adapted with the coal feed load and wear stage. The differential pressure deviation value is obtained by calculating the difference between the actual differential pressure value and the differential pressure target value. The positive or negative polarity of the deviation value represents the direction of the actual working condition deviating from the optimal state, and the absolute value represents the degree of deviation.

[0039] Then, dynamic compensation is initiated, strictly adhering to the constraint of not altering the opening ratio of the cold and hot air regulating mechanisms. This means the compensation process only adjusts the total primary air volume in the same direction, with the openings of the cold and hot air always increasing or decreasing synchronously according to the previously calculated distribution ratio. This ensures the inlet air temperature after mixing remains essentially constant, preventing air volume compensation from interfering with the mill's drying output and outlet temperature control. Specifically, during compensation, the absolute value of the differential pressure deviation is first compared to a preset differential pressure fluctuation threshold. This threshold is a pre-set dead zone parameter used to filter out normal, minor random fluctuations in the differential pressure signal, preventing regulation oscillations and equipment wear caused by frequent reciprocating movements of the actuators. When the absolute value of the differential pressure deviation is less than or equal to the differential pressure fluctuation threshold, the current differential pressure is determined to be within the normal fluctuation range, and no correction is made to the initial air volume regulation command; the original command is directly output. When the absolute value of the differential pressure deviation is greater than the differential pressure fluctuation threshold, the mill's internal operating conditions are determined to deviate from the optimal range, and the deceleration process is initiated. Differential pressure correction involves adjusting the initial airflow setting in the airflow adjustment command according to the polarity of the differential pressure deviation. If the differential pressure deviation is positive, meaning the actual differential pressure is higher than the target value, it indicates that the ventilation resistance inside the mill is too high and the coal powder carrying capacity is insufficient, posing a risk of mill blockage. In this case, a positive correction is executed, increasing the total airflow setting proportionally to the deviation, while simultaneously increasing the opening of the cold and hot air adjustment mechanisms to improve the total primary air throughput and carrying capacity, and reducing the differential pressure inside the mill to a reasonable range. If the differential pressure deviation is negative, meaning the actual differential pressure is lower than the target value, it indicates that the airflow inside the mill is relatively excessive and the coal seam is too thin, resulting in energy waste and excessively fine coal powder. In this case, a negative correction is executed, decreasing the total airflow setting proportionally to the deviation, while simultaneously decreasing the opening of the cold and hot air adjustment mechanisms to reduce redundant airflow and optimize pulverizing power consumption and coal powder fineness. Furthermore, the correction process is constrained by upper and lower limits for compensation to prevent large fluctuations in operating conditions caused by excessive single correction. Finally, the corrected final airflow adjustment command is output.

[0040] Furthermore, in the method provided in this application embodiment, the initial air volume adjustment command is dynamically compensated according to the differential pressure deviation value, including: when the differential pressure deviation value is greater than a preset differential pressure fluctuation threshold, the air volume setting value in the initial air volume adjustment command is positively or negatively corrected according to the polarity of the differential pressure deviation value to obtain the final primary air volume adjustment command.

[0041] Specifically, the first step is to define a preset differential pressure fluctuation threshold. This threshold is a dead zone parameter pre-set by the control system. In order to filter out the small differential pressure fluctuations caused by normal turbulence in the air-powder flow field and random noise from pressure sampling, a formal correction is only triggered when the absolute value of the deviation exceeds this threshold. It serves as the boundary for distinguishing between normal operating condition fluctuations and substantial operating condition deviations. When the absolute value of the differential pressure deviation is greater than the preset differential pressure fluctuation threshold, the system first identifies the polarity of the differential pressure deviation, that is, the positive or negative sign of the deviation value. The polarity directly corresponds to the direction of deviation of the operating state inside the mill. A positive deviation means that the actual differential pressure is higher than the target value, and a negative deviation means that the actual differential pressure is lower than the target value. Then, based on the polarity, a positive or negative correction is performed. The entire correction process only adjusts the total air volume setting value in the initial air volume adjustment command. The opening ratio of cold air and hot air follows the previously calculated and determined ratio benchmark. The opening of both air and hot air increases and decreases synchronously and proportionally with the total air volume setting value.

[0042] Positive correction is triggered when the differential pressure deviation is positive, meaning the actual differential pressure is higher than the preset differential pressure target value and the deviation exceeds the fluctuation threshold. Here, positive correction refers to the direction of adjustment, which is to increase the initial air volume setting value. This corresponds to the adjustment action of increasing the total primary air throughput. The underlying operating logic is that a positive differential pressure deviation means that the coal seam thickness inside the mill is too large, the coal powder accumulation is increased, and the ventilation resistance is increased. This usually occurs when the coal feed rate suddenly increases, the grindability of the coal deteriorates, or the wear of the grinding parts is aggravated, leading to a decrease in pulverizing efficiency. If the air is not increased in time, it will further develop into a mill blockage failure. The specific execution process of positive correction is as follows: the system first calculates the corresponding air volume compensation increment based on the magnitude of the differential pressure deviation value and the preset deviation-air volume correction gain coefficient. The larger the deviation magnitude, the larger the air volume compensation increment. At the same time, the maximum increment limit for a single correction is set. Then, the air volume compensation increment is superimposed on the air volume setting value of the initial air volume adjustment command to obtain the corrected total air volume target value. Then, the opening commands of the cold and hot air adjustment mechanisms are amplified synchronously according to the original cold and hot air opening ratio.

[0043] The final primary airflow adjustment command, after positive correction, is generated. This reduces the differential pressure inside the mill by increasing the total carrying capacity of the primary air, alleviating the risk of coal seam accumulation and allowing the air-coal state inside the mill to return to the optimal range. Negative correction is triggered when the differential pressure deviation is negative, meaning the actual differential pressure is lower than the preset differential pressure target value and the deviation exceeds the fluctuation threshold. Here, negative correction refers to lowering the initial airflow setting value, corresponding to reducing the adjustment action of the total primary airflow. The underlying operating logic is that a negative differential pressure deviation means that the coal seam thickness inside the mill is too thin, the coal storage is insufficient, and the primary airflow is relatively excessive. This usually occurs when the coal feed rate drops instantaneously, the coal quality is easy to grind, or the grinding capacity is excessive during the new roller period. Continuous high airflow will cause waste of primary air fan power consumption and excessively fine coal powder. The increase in combustible content in fly ash is caused by the system calculating the corresponding air volume reduction based on the absolute value of the differential pressure deviation and the preset deviation-air volume correction gain coefficient. The larger the deviation, the greater the air volume reduction. At the same time, a minimum reduction limit is set for the maximum reduction in a single correction to prevent insufficient coal powder carrying caused by a sudden drop in air volume. Then, the air volume reduction is subtracted from the air volume setting value of the initial air volume adjustment command to obtain the corrected total air volume target value. Then, the opening commands of the cold and hot air adjustment mechanisms are reduced synchronously according to the original cold and hot air opening ratio. Finally, the final air volume adjustment command after negative correction is generated. By reducing redundant air volume, the power consumption of pulverizing is reduced, the fineness distribution of coal powder is optimized, and the operating state inside the mill returns to the economic optimal range.

[0044] Furthermore, in the method provided in this application embodiment, the wear stage quantification factor is calculated based on the cumulative running time of the grinding part and the real-time gap value of the grinding part, including: comparing the cumulative running time of the grinding part with a preset rated running time of the grinding part to obtain the time-based wear ratio; comparing the real-time gap value of the grinding part with a preset gap value of the grinding part in its new state and a preset limit wear gap value of the grinding part to obtain the gap wear ratio; and performing a weighted calculation on the time-based wear ratio and the gap wear ratio to obtain the wear stage quantification factor.

[0045] Specifically, the wear ratio calculation is performed first, clarifying the physical definitions of two basic parameters. The cumulative running time of the grinding components refers to the cumulative effective time the coal mill is in a loaded grinding operation state since the replacement and commissioning of core grinding components such as the grinding roller sleeve and grinding disc liner. During the statistics, periods of no-load standby, shutdown for maintenance, and start-stop transitions that do not generate effective grinding wear are automatically excluded, retaining only the actual grinding time. This is a macroscopic indicator reflecting the fatigue wear progress of the wear-resistant layer of the grinding components from a cumulative time perspective. The preset rated running time of the grinding components is the theoretical total running time calibrated by the equipment manufacturer based on standard coal quality and rated output conditions, representing the normal wear of the wear-resistant layer of the grinding components from a brand-new state to the scrap limit. This serves as the full-scale benchmark value for assessing the wear degree in the time dimension. Subsequently, the wear ratio is obtained through ratio calculation, and the calculation formula is as follows: ; In the formula This represents the percentage of wear and tear over time. The cumulative running time of the grinding parts, The rated operating time of the grinding part is defined as the wear percentage over time, which ranges from [0,1]. A value of 0 corresponds to the initial state of the grinding part when it is newly put into operation, while a value of 1 corresponds to the wear node that has reached the rated operating time. The closer the value is to 1, the higher the degree of wear accumulation in the time dimension. This indicator can intuitively reflect the time progress of the grinding part in its entire life cycle and has a good characterization ability for slow deformation fatigue wear.

[0046] Simultaneously, the wear ratio calculation based on physical morphology is performed. First, the physical meaning of three basic parameters is clarified. The real-time gap value of the grinding part refers to the real-time detected value of the working gap between the outer working surface of the grinding roller sleeve and the working surface of the grinding disc liner. This is typically collected in real-time by a high-precision displacement sensor installed on the grinding roller support or hydraulic loading circuit. This gap continuously increases as the wear-resistant layer on the surface of the grinding part wears away. It is a microscopic, concrete indicator that directly reflects the wear degree of the grinding part from a physical morphology perspective. The preset gap value for the grinding part in its brand-new state is the initial working gap when the grinding part is newly installed and debugged, without any wear, serving as the zero-point benchmark for gap wear calculation. The preset limit wear gap value for the grinding part is the maximum allowable increase in working gap compared to the brand-new state when the wear-resistant layer of the grinding part wears to the scrap threshold, serving as the full-scale benchmark for assessing the wear degree in the gap dimension. During calculation, the gap increase is first calculated, i.e., the difference between the real-time gap value and the gap value in the brand-new state, directly reflecting the gap expansion caused by wear. Then, the gap increase is compared with the limit wear gap value to obtain the gap wear ratio. The calculation formula is as follows: ; In the formula The percentage of clearance wear. This represents the real-time gap value of the grinding parts. This represents the clearance value of the grinding part in its brand new state. The value represents the limit wear clearance of the grinding parts. The wear ratio of the clearance is also in the range of [0,1]. A value of 0 corresponds to a brand new state with zero wear, while a value of 1 corresponds to a state where the clearance has reached the scrap limit. This indicator can directly reflect the actual contact state of the grinding pair and has a more direct indication of the decline in grinding capacity.

[0047] After calculating the wear ratio in both dimensions, the final wear stage quantification factor is obtained by merging the two-dimensional information through weighted calculation. Weighted calculation involves assigning preset weight coefficients to the duration-based wear ratio and the interval-based wear ratio, and then obtaining the comprehensive quantification result through weighted summation. The weight coefficients can be flexibly adjusted according to the on-site coal quality, operating load, and equipment characteristics. The sum of the two weights is always 1. The calculation formula is as follows: ; In the formula, K is the quantification factor for the wear stage. This is the weighting coefficient for the proportion of wear and tear over time. The weighting coefficient for the proportion of gap wear is used. For example, in high-load, hard coal operation scenarios, the wear rate of grinding parts is fast and the gap change has a more significant impact on grinding capacity. The weight of the proportion of gap wear can be appropriately increased to improve the sensitivity of wear assessment. In low-load, soft coal long-cycle operation scenarios, the proportion of fatigue wear is higher. The weight of the proportion of time wear can be appropriately increased to ensure the stability of assessment. The final wear stage quantification factor is a dimensionless standardized value with a value range of [0,1]. 0 corresponds to the initial state of the grinding parts when they are newly put into operation, and 1 corresponds to the scrap state of the grinding parts when they reach the limit of wear. The larger the value, the deeper the overall wear of the grinding parts. The dual-dimensional weighted fusion method can effectively eliminate the bias caused by a single assessment dimension. For example, in long-term low-load operation scenarios, the proportion of time wear is high but the actual physical wear is light, or in short-term high-load grinding of hard coal scenarios, the gap wear progresses quickly but the proportion of time wear is low. After fusion, the true wear stage of the current grinding parts can be more accurately represented.

[0048] Furthermore, in the method provided in this application embodiment, the preset basic abrasiveness parameter and basic grinding area parameter are corrected according to the wear stage quantification factor, including: attenuating the basic abrasiveness parameter according to the wear stage quantification factor to obtain the corrected abrasiveness parameter; and reducing the basic grinding area parameter according to the wear stage quantification factor to obtain the corrected grinding area parameter.

[0049] Specifically, using the calculated wear stage quantification factor as the correction input, targeted physical characteristic calibrations are performed on the basic grindability parameters and basic grinding area parameters. The wear stage quantification factor is a continuous quantified value in the range of 0 to 1, obtained by weighted fusion calculation of the cumulative running time of the grinding component and the real-time gap value of the grinding component in the previous steps. The closer the value is to 1, the deeper the wear of the grinding component. A value of 0 corresponds to the initial state of a brand-new, unworn grinding component, while a value of 1 corresponds to the critical state of the grinding component reaching the ultimate wear threshold, making it the core carrier for converting the physical wear degree of the equipment into a quantifiable and calculable value. The basic grindability parameter is a benchmark grindability index obtained by on-site calibration or laboratory tests under the condition that the grinding parts are brand new and the coal type fed into the furnace is fixed. It is equivalent to the engineered Hardgrove Grindability Index and characterizes the difficulty of grinding the current coal type with brand new grinding parts. The higher the value, the less effort is required to grind coal powder and the higher the pulverization efficiency under the same working conditions. The basic grinding area parameter is the geometric area of ​​the effective contact and rolling working surface formed by the grinding roller and the grinding disc liner under the rated loading pressure when the grinding parts are brand new. It is calibrated by the original structural dimensions of the equipment. The larger the area, the more raw coal can be processed per unit time.

[0050] Based on this, two correction calculations are performed simultaneously. The first is the attenuation correction for the basic grindability parameters. From a physical perspective, as the grinding parts wear continuously, the grinding edges of the grinding rollers and grinding disc liners gradually become blunt, and the surface roughness of the working surface continues to decrease. The cutting and crushing capabilities during the grinding process will continuously weaken as wear intensifies, which is equivalent to a decrease in the actual grindability of the current coal type. Therefore, the specific process of attenuation correction is as follows: the system first retrieves the baseline value of the basic grindability parameters that is completely matched with the current coal type and coal mill model from the built-in parameter library. Then, the quantification factor of the wear stage is substituted into the preset grindability attenuation correction formula. A linear or piecewise nonlinear attenuation logic is used, and the baseline value is down-calculated with the quantification factor of the wear stage as the attenuation weight. The higher the degree of wear and the larger the value of the quantification factor, the greater the attenuation of the grindability parameters. Finally, the corrected grindability parameters output can accurately match the actual grinding efficiency of the coal mill under the current wear state and restore the grindability level of the coal type under real working conditions.

[0051] The second item is the reduction and correction of the basic grinding area parameters. From the perspective of equipment geometry, after long-term operation of the grinding components, the grinding roller surface will show arc-shaped wear and indentation, and the working surface of the grinding disc liner will wear and thin evenly. The effective contact grinding area of ​​the two will gradually narrow along the radial and axial directions. The actual working surface area participating in grinding will continue to decrease as wear intensifies. Therefore, the specific process of reduction and correction is that the system first retrieves the basic grinding area benchmark value of the grinding components in a brand-new state, and then substitutes the wear stage quantification factor into the preset grinding area reduction and correction model. According to the geometric deformation law corresponding to wear, the effective working surface area is reduced proportionally. The larger the quantification factor, the higher the area reduction ratio. The finally obtained corrected grinding area parameters can accurately reflect the actual effective grinding working surface scale of the coal mill in the current wear stage.

[0052] Furthermore, in the method provided in this application embodiment, calculating the appropriate loading force setting value and appropriate air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state includes: reading the corrected grindability parameter, the corrected grinding area parameter, and the current coal feed rate, inputting them into a preset output mapping relationship table, and looking up the table to obtain the reference loading force value and the reference air-coal ratio value; reading the preset target coal powder fineness threshold, inputting the reference loading force value and the target coal powder fineness threshold into a preset loading force correction relationship table, and looking up the table to obtain the loading force correction ratio; multiplying the reference loading force value by the loading force correction ratio to obtain the appropriate loading force setting value; reading the preset coal powder uniformity index threshold, inputting the reference air-coal ratio value and the coal powder uniformity index threshold into a preset air-coal ratio correction relationship table, and looking up the table to obtain the air-coal ratio correction ratio; multiplying the reference air-coal ratio value by the air-coal ratio correction ratio to obtain the appropriate air-coal ratio coefficient.

[0053] Specifically, the system first synchronously reads three types of input parameters: the corrected grindability parameter obtained after prior attenuation correction, which is the equivalent coal type grindability characteristic value that matches the current wear degree of the grinding parts, truly reflecting the actual grinding and cutting capacity of the coal mill after wear; the corrected grinding area parameter obtained after prior reduction correction, which is the actual area of ​​the effective contact and rolling working surface between the grinding roller and the grinding disc under the current wear state, directly determining the upper limit of the single grinding process of the coal mill; and the real-time collected current coal feed rate, which represents the current output load demand of the pulverizing system.

[0054] Subsequently, the system inputs the three types of parameters into a preset output mapping table to complete the first-level benchmark lookup. This mapping table is a multi-dimensional discrete mapping database that has been pre-established by accumulating a large amount of measured data through coal mill bench tests and on-site hot calibration. It uses grindability parameters, grinding area, and coal feed rate as input dimensions and outputs benchmark operating parameters that can achieve basic pulverization effects under corresponding working conditions. During the lookup process, a linear interpolation algorithm is used to match the optimal result for non-node values, ultimately outputting reference loading force values ​​and reference air-coal ratio values. This set of reference values ​​only matches the basic working condition parameters of equipment wear status and output load, and has not yet incorporated the refined requirements of coal powder quality. Based on this, the system performs two parameter corrections in parallel. The first is the calculation of the adaptive loading force setpoint. The system first reads the preset target coal powder fineness threshold, i.e., based on stable boiler combustion, The burnout rate requires a pre-set control index for pulverized coal particle size, typically represented by the R90 sieve residue rate. A smaller threshold indicates a higher requirement for pulverized coal fineness. Subsequently, the reference loading force value and the target pulverized coal fineness threshold are input into a pre-set loading force correction relationship table. This correction relationship table is a pre-calibrated specialized database reflecting the correspondence between loading force magnitude and pulverized coal fineness. It clarifies the loading force adjustment ratio required to achieve the specified fineness under different benchmark loading forces. After looking up the table, the loading force correction ratio for the corresponding working condition is obtained. Finally, the reference loading force value is multiplied by the loading force correction ratio to obtain the appropriate loading force setting value that adapts to the current wear state, coal feed load, and pulverized coal fineness requirements. When the target fineness requirement is higher than the benchmark working condition, the correction ratio is greater than 1, correspondingly increasing the loading force to ensure the grinding effect. Conversely, the ratio is less than 1 to avoid excessive loading force causing unnecessary power waste.

[0055] The second step is the calculation of the adaptive air-coal ratio coefficient. The system first reads the preset coal powder uniformity index threshold, which is a preset control index characterizing the uniformity of coal powder particle size distribution, also known as the coal powder uniformity n-value. The higher the value, the more concentrated the coal powder particle size distribution, which is more conducive to stable boiler combustion and reducing fly ash carbon content. It is the core indicator for measuring the carrying and sorting effect of primary air. Then, the reference air-coal ratio value and the coal powder uniformity index threshold are input into the preset air-coal ratio correction relationship table. This correction relationship table is a special mapping library obtained through cold flow field test and hot pulverizing test. It clarifies the air-coal ratio adjustment range required to achieve the specified coal powder uniformity under different benchmark air-coal ratios. After looking up the table, the air-coal ratio correction ratio under the corresponding working condition is obtained. Finally, the reference air-coal ratio value is multiplied by the air-coal ratio correction ratio to obtain the adaptive air-coal ratio coefficient that adapts to the current wear state, coal feed load and coal powder uniformity requirements. By dynamically adjusting the air-coal ratio, the carrying and sorting capacity of primary air is optimized to ensure that the uniformity of coal powder particle distribution meets the standards.

[0056] Furthermore, in the method provided in this application embodiment, the dynamic primary air volume setting value is calculated based on the adapted air-coal ratio coefficient and the current coal feed rate, including: reading the real-time sampled value of the current coal feed rate, performing a moving average filter on the real-time sampled value to obtain the filtered coal feed rate; reading the adapted air-coal ratio coefficient, multiplying the adapted air-coal ratio coefficient by the filtered coal feed rate to obtain the theoretical primary air volume value; reading the current inlet air temperature value of the coal mill, performing density compensation calculation on the theoretical primary air volume value based on the ratio of the inlet air temperature value to the preset standard air temperature value to obtain the compensated primary air volume value; and determining the compensated primary air volume value as the dynamic primary air volume setting value.

[0057] Specifically, in the initial calculation stage, the system first reads the real-time sampled value of the current coal feed output by the coal feed detection device, and performs moving average filtering on it. Moving average filtering is a time-domain smoothing filtering algorithm. Specifically, the system continuously collects multiple sets of instantaneous coal feed data at a fixed sampling period, sets a moving data window of length N, and removes the earliest set of historical data in the window after each new set of sampled data is collected. The arithmetic mean of all N sets of data in the window is then calculated. The corresponding calculation formula is the filtered coal feed: ; in The i-th group of coal feed sampling values ​​within the window can be filtered out through this processing. This process can remove high-frequency random disturbances caused by instantaneous shaking of the coal feeder belt scale and uneven coal flow, and avoid frequent oscillations of the air volume setpoint with the coal feed sampling noise. The output is a stable and reliable filtered coal feed, which serves as a stable load benchmark for air volume calculation.

[0058] The system then reads the adaptive air-coal ratio coefficient calculated in the previous steps. This coefficient is the optimal ratio coefficient corresponding to the primary air volume per unit coal feed rate, calibrated by combining the wear state of the grinding mill parts and the requirements for coal powder fineness and uniformity. It directly represents the benchmark of primary air volume required per ton of raw coal entering the mill, and is denoted as [missing information]. Multiply the adaptive air-to-coal ratio coefficient by the filtered coal feed rate to obtain the theoretical primary air volume value: ; This value is the volumetric air volume benchmark under preset standard air temperature conditions, and does not take into account the impact of inlet air temperature changes on air density and, consequently, on the primary air powder drying capacity during actual operation.

[0059] Next, density compensation calculations are performed. Here, we first define the core feature term: the current inlet air temperature of the coal mill is the actual Celsius temperature of the primary air before it enters the coal mill cylinder after the hot and cold air mixture is collected in real time by a temperature sensor, denoted as [missing information]. Its value will fluctuate dynamically with boiler load, ambient temperature, and hot / cold air conditioning status. The standard air temperature value is the standard operating condition Celsius air temperature reference used when calibrating the air-coal ratio coefficient test. It is usually taken as the rated inlet air temperature corresponding to the equipment design operating condition, denoted as . The temperature reference condition corresponding to the theoretical primary air volume value is used. The physical principle of density compensation calculation is based on the ideal gas law under normal pressure. The operating pressure of the primary air system is approximately constant. At this time, the air density is inversely proportional to the thermodynamic temperature. The higher the air temperature, the lower the air density. The lower the air mass flow rate corresponding to the same volume flow rate of primary air, the weaker the actual ability to carry coal powder and dry raw coal. If the theoretical air volume value is used directly for control, when the air temperature is too high, the actual air-coal ratio will be insufficient, the powder carrying capacity will decrease, and problems such as mill blockage and excessive coal powder fineness will occur. When the air temperature is too low, there will be problems of redundant air volume and artificially high power consumption of the primary air fan.

[0060] The density compensation calculation process consists of three steps. The first step is temperature system conversion, which converts the current inlet air temperature value measured in Celsius and the preset standard air temperature value into thermodynamic temperatures. The corresponding formula is: ; in For the inlet air temperature thermodynamic temperature, The standard air temperature is the thermodynamic temperature.

[0061] The second step is to calculate the density compensation coefficient. Based on the inverse relationship between air density and thermodynamic temperature under normal pressure, to ensure that the mass flow rate of the primary air, i.e., the actual powder carrying and drying capacity, is consistent with the standard design value, the volumetric air volume needs to be increased proportionally with the increase of thermodynamic temperature. Therefore, the density compensation coefficient is: ; When the actual inlet air temperature is higher than the standard air temperature, the compensation coefficient is greater than 1, and the volumetric air volume setting needs to be increased to ensure that the air mass flow rate meets the standard. When the actual inlet air temperature is lower than the standard air temperature, the compensation coefficient is less than 1, and the volumetric air volume setting should be reduced accordingly to avoid air volume redundancy. The third step is to calculate the compensated air volume by multiplying the theoretical primary air volume value by the density compensation coefficient to obtain the compensated primary air volume value. ; This value has eliminated the impact of inlet air temperature fluctuations on the actual efficiency of air volume, and can truly reflect the primary air volume flow rate benchmark that meets the pulverization requirements; finally, the system will determine the compensated primary air volume value as the dynamic primary air volume setpoint, which will serve as the benchmark for subsequent air volume adjustment mechanism opening control and hot and cold air ratio calculation.

[0062] Furthermore, in the method provided in this application embodiment, generating and issuing an initial air volume adjustment command and an initial loading force adjustment command based on the dynamic primary air volume setting value and the adaptive loading force setting value includes: generating an initial air volume adjustment command for controlling the opening of the primary air adjustment mechanism based on the dynamic primary air volume setting value; generating the initial loading force adjustment command for controlling the hydraulic loading mechanism based on the adaptive loading force setting value; synchronously calculating the opening distribution ratio of the cold air adjustment mechanism and the hot air adjustment mechanism based on the dynamic primary air volume setting value, generating a cold and hot air adjustment command for maintaining the coal mill outlet temperature, and issuing the cold and hot air adjustment command and the initial air volume adjustment command synchronously.

[0063] Specifically, the system first generates an initial air volume adjustment command based on the dynamic primary air volume setpoint. The dynamic primary air volume setpoint is the optimal target value of the total primary air flow calculated by the preceding steps in combination with the wear state of the grinding components, coal feed load, and air temperature and density compensation. It serves as the total benchmark to ensure the matching of air-coal ratio, powder carrying capacity, and coal powder fineness. The primary air adjustment mechanism is usually the primary air total adjustment baffle at the inlet of the coal mill, which is the actuator that controls the total primary air flow entering the coal mill cylinder. Specifically, the system first collects the actual flow feedback value of the current primary air main pipe, subtracts it from the dynamic primary air volume setpoint to obtain the flow deviation, and then combines the preset valve flow characteristic curve and PID adjustment algorithm to convert the flow target value into the target opening value of the primary air adjustment mechanism, which is then encapsulated as a standard control signal, i.e., the initial air volume adjustment command. This command is the initial feedforward benchmark for total air volume control and has not yet been superimposed with subsequent differential pressure feedback compensation. Simultaneously, the system generates an initial loading force adjustment command in parallel. The adaptive loading force setpoint is the target grinding pressure value calculated in the previous step, combining the equipment grinding capacity after wear correction, the coal feed rate, and the target coal powder fineness. It directly determines the squeezing and grinding intensity of the grinding rollers on the raw coal. The hydraulic loading mechanism refers to the coal mill grinding pressure application system composed of a hydraulic station, loading cylinder, and accumulator, which is the execution carrier for loading force adjustment. Specifically, the system converts the adaptive loading force setpoint into the target working pressure of the hydraulic system, combines it with the actual pressure feedback value of the current hydraulic circuit, calculates the target opening of the proportional pressure valve through the closed-loop adjustment logic of the hydraulic control circuit, encapsulates it into an initial loading force adjustment command, and sends it to the hydraulic station to adjust the grinding pressure of the grinding rollers in real time, so as to accurately match the grinding requirements under the current wear state.

[0064] While generating total air volume and loading force commands, the system uses a dynamic primary air volume setpoint as a fixed total constraint, and simultaneously calculates the opening distribution ratio of the cold air regulating mechanism and the hot air regulating mechanism to generate cold and hot air regulating commands. The cold air regulating mechanism and the hot air regulating mechanism correspond to the cold primary air damper and the hot primary air damper at the coal mill inlet, respectively. The hot air is taken from the high-temperature primary air at the outlet of the boiler air preheater, which is responsible for drying the raw coal and raising the outlet temperature. The cold air is taken from the cold primary air header, which is used to reduce the mixed air temperature and assist in regulating the outlet temperature. The coal mill outlet temperature is the temperature when the air-coal mixture leaves the coal mill. It is a core indicator related to the safe operation of the pulverizing system and the quality of coal powder drying, and it needs to be stable within the preset target range.

[0065] The specific ratio calculation process involves locking the primary air volume benchmark unchanged throughout the entire process. This means that the total air volume after the combination of hot and cold air opening adjustments is always equal to the dynamic primary air volume setpoint, and the total air-coal ratio will not change due to temperature adjustments. Subsequently, the system collects the real-time measurement value of the coal mill outlet temperature and compares it with the preset target temperature range to obtain the temperature deviation value. Based on the polarity of the deviation, the opening ratio of hot and cold air is adjusted in the opposite direction: when the outlet temperature is higher than the upper limit of the target range, the opening ratio of the cold air adjustment mechanism is increased proportionally and the opening ratio of the hot air adjustment mechanism is decreased to reduce the inlet mixed air temperature and suppress the outlet temperature; when the outlet temperature is lower than the lower limit of the target range, the opening ratio of cold air is decreased proportionally and the opening ratio of hot air is increased to increase the mixed air temperature and raise the outlet temperature, ultimately driving the outlet temperature back to the target range. The generated hot and cold air adjustment commands are synchronously sent to the corresponding actuators along with the initial air volume adjustment command and the initial loading force adjustment command, ensuring the synchronicity of the adjustments of air volume, loading force, and air temperature.

[0066] Furthermore, in the method provided in this application embodiment, the opening ratio of the cold air regulating mechanism and the hot air regulating mechanism is simultaneously calculated based on the dynamic primary air volume setting value, and a cold and hot air regulating command for maintaining the coal mill outlet temperature is generated. This includes: obtaining the actual measured value of the coal mill outlet temperature; comparing the actual measured value with a preset target temperature range to obtain a temperature deviation value; and, based on the polarity of the temperature deviation value and with the dynamic primary air volume setting value as a total constraint, adjusting the opening ratio of the cold air regulating mechanism and the opening ratio of the hot air regulating mechanism in opposite directions to bring the coal mill outlet temperature back to the target temperature range. The adjustment process of the opening ratio does not modify the value of the dynamic primary air volume setting value.

[0067] Specifically, the actual measured value of the outlet temperature is first collected in real time by a contact-type temperature sensor at the coal mill outlet, and recorded as follows: Then compare it with the preset target temperature range. The comparison was conducted, with the target temperature range being a pre-set allowable temperature fluctuation range based on the drying requirements of the coal type entering the furnace and the explosion-proof safety standards of the pulverizing system. This ensures that the moisture content of the pulverized coal meets the boiler combustion requirements while avoiding the safety risk of spontaneous combustion of the pulverized coal due to excessive temperature. The midpoint of the range was used as the target benchmark value during the comparison. The temperature deviation value was calculated. The polarity of the deviation value indicates the direction of temperature deviation. This indicates that the outlet temperature is higher than the target baseline. This indicates that the outlet temperature is lower than the target baseline. The larger the absolute value of the deviation, the more serious the deviation from the control target.

[0068] The system then uses the dynamic primary air volume setpoint. To ensure rigid total volume constraints, the opening ratio is adjusted. The dynamic primary air volume setpoint is the optimal target value of the total primary air flow calculated in advance based on the wear state of the grinding mill parts, coal feed load, and air temperature and density compensation. It serves as the benchmark to ensure air-coal ratio matching, powder carrying capacity, and coal powder fineness compliance. It remains unchanged throughout the process regardless of temperature adjustment. The corresponding actuators are the cold air adjustment mechanism and the hot air adjustment mechanism, which correspond to the cold primary air adjustment baffle and the hot primary air adjustment baffle at the coal mill inlet, respectively. The hot air is taken from the high-temperature primary air at the boiler air preheater outlet and plays a core role in drying raw coal and raising the outlet temperature. The cold air is taken from the cold primary air header and is used to dilute the mixed air temperature and assist in lowering the outlet temperature. The system first establishes the flow linkage relationship between the cold and hot air: ; in For cold air flow, For hot air flow, the corresponding cool air opening ratio at the actuator opening level is... Ratio of hot air opening satisfy The opening ratio refers to the proportion of the equivalent opening of a single damper to the total equivalent opening of the dampers, which corresponds one-to-one with the flow ratio of the corresponding branch.

[0069] Next, the system performs reverse linkage adjustment based on the polarity of the temperature deviation value. The adjustment process uses a PID closed-loop algorithm to achieve continuous smooth control to avoid temperature oscillations: when When the outlet temperature is too high, the system increases the proportion of cold air opening proportionally to the deviation. Simultaneously reduce the proportion of hot air opening by the same amount. By increasing the proportion of cold air to reduce the inlet mixed air temperature, the outlet temperature of the coal mill is lowered. Since the absolute values ​​of the changes in the opening degrees of both are equal, the total air volume corresponding to the total opening degree is always equal to the dynamic primary air volume setpoint. ;when When the outlet temperature is low, the system proportionally reduces the proportion of cold air opening. Simultaneously increase the proportion of hot air opening by the same amount By increasing the proportion of hot air, the inlet mixed air temperature is increased, thereby raising the outlet temperature. At the same time, the total opening and total air volume remain constant. The entire adjustment process only adjusts the ratio of hot and cold air, without modifying the value of the dynamic primary air volume setting. Finally, the coal mill outlet temperature is driven to gradually return to the preset target temperature range, and the corresponding hot and cold air adjustment commands and total air volume commands are issued simultaneously.

[0070] In summary, the coal mill pulverizing collaborative control method based on dynamic air volume regulation provided in this application has the following technical effects: By collecting the cumulative running time and real-time gap value of the grinding components, the wear stage quantification factor is calculated. This dynamically corrects the basic grindability parameters and basic grinding area parameters. The loading force setpoint and dynamic primary air volume setpoint are calculated in conjunction with the calculation to adapt to the current wear state. The outlet temperature is independently controlled by the cold and hot air ratio method with the total air volume locked. Combined with differential pressure feedback, the air volume is dynamically compensated. Ultimately, the target coal powder fineness and uniformity can be stably maintained throughout the entire wear cycle of the grinding components, reducing the overall power consumption of the pulverizing system, eliminating the coupling interference of temperature regulation on the total air volume, effectively preventing the risk of mill blockage, and achieving efficient, stable, and safe operation of the pulverizing system throughout its entire life cycle.

[0071] Example 2 is based on the same inventive concept as the coal mill pulverizing collaborative control method based on dynamic air volume regulation in the previous examples, such as... Figure 2 As shown in the embodiment of this application, a coal mill pulverizing collaborative control system based on dynamic air volume regulation is provided. The system includes: The data acquisition module 11 is used to acquire the operating parameters of the coal mill, extract the cumulative running time of the grinding parts and the real-time gap value of the grinding parts, and calculate the wear stage quantification factor based on the cumulative running time of the grinding parts and the real-time gap value of the grinding parts; the correction module 12 is used to correct the preset basic grindability parameters and basic grinding area parameters based on the wear stage quantification factor to obtain the corrected grindability parameters and corrected grinding area parameters; the calculation module 13 is used to calculate the appropriate loading force setting value and appropriate air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state based on the corrected grindability parameters, the corrected grinding area parameters, and the current coal feed rate; the dynamic module 14 is used to calculate the dynamic primary air volume setting value based on the appropriate air-coal ratio coefficient and the current coal feed rate; the execution module 15 is used to generate and issue the initial air volume adjustment command and the initial loading force adjustment command based on the dynamic primary air volume setting value and the appropriate loading force setting value to maintain the coal mill outlet temperature within the preset target temperature range.

[0072] Furthermore, the acquisition module 11 is also used to perform the following steps: acquiring the actual differential pressure value during the operation of the coal mill, comparing the actual differential pressure value with the preset differential pressure target value to obtain the differential pressure deviation value, dynamically compensating the initial air volume adjustment command based on the differential pressure deviation value, and outputting the final primary air volume adjustment command; wherein, the dynamic compensation process does not change the opening ratio benchmark of the cold air adjustment mechanism and the hot air adjustment mechanism.

[0073] Furthermore, the acquisition module 11 is also used to perform the following steps: when the differential pressure deviation value is greater than the preset differential pressure fluctuation threshold, the air volume setting value in the initial air volume adjustment command is positively or negatively corrected according to the polarity of the differential pressure deviation value to obtain the final air volume adjustment command.

[0074] Furthermore, the acquisition module 11 is also used to perform the following steps: comparing the cumulative running time of the grinding part with the preset rated running time of the grinding part to obtain the time-based wear ratio; comparing the real-time gap value of the grinding part with the preset gap value of the grinding part in its new state and the preset limit wear gap value of the grinding part to obtain the gap wear ratio; and performing a weighted calculation on the time-based wear ratio and the gap wear ratio to obtain the wear stage quantification factor.

[0075] Furthermore, the correction module 12 is also used to perform the following steps: attenuating the basic grindability parameter according to the wear stage quantification factor to obtain the corrected grindability parameter; reducing the basic grinding area parameter according to the wear stage quantification factor to obtain the corrected grinding area parameter.

[0076] Furthermore, the calculation module 13 is also used to perform the following steps: reading the corrected grindability parameter, the corrected grinding area parameter, and the current coal feed rate, inputting them into a preset output mapping relationship table, and looking up the table to obtain the reference loading force value and the reference air-coal ratio value; reading the preset target coal powder fineness threshold, inputting the reference loading force value and the target coal powder fineness threshold into a preset loading force correction relationship table, and looking up the table to obtain the loading force correction ratio; multiplying the reference loading force value by the loading force correction ratio to obtain the adaptive loading force setting value; reading the preset coal powder uniformity index threshold, inputting the reference air-coal ratio value and the coal powder uniformity index threshold into a preset air-coal ratio correction relationship table, and looking up the table to obtain the air-coal ratio correction ratio; multiplying the reference air-coal ratio value by the air-coal ratio correction ratio to obtain the adaptive air-coal ratio coefficient.

[0077] Furthermore, the dynamic module 14 is also used to perform the following steps: read the real-time sampled value of the current coal feed rate, perform a moving average filter on the real-time sampled value to obtain the filtered coal feed rate; read the adaptive air-coal ratio coefficient, multiply the adaptive air-coal ratio coefficient by the filtered coal feed rate to obtain the theoretical primary air volume value; read the current inlet air temperature value of the coal mill, perform density compensation calculation on the theoretical primary air volume value according to the ratio of the inlet air temperature value to the preset standard air temperature value to obtain the compensated primary air volume value; and determine the compensated primary air volume value as the dynamic primary air volume setpoint.

[0078] Furthermore, the execution module 15 is also used to perform the following steps: generating an initial air volume adjustment command for controlling the opening of the primary air adjustment mechanism based on the dynamic primary air volume setting value; generating the initial loading force adjustment command for controlling the hydraulic loading mechanism based on the adaptive loading force setting value; synchronously calculating the opening distribution ratio of the cold air adjustment mechanism and the hot air adjustment mechanism based on the dynamic primary air volume setting value, generating a cold and hot air adjustment command for maintaining the coal mill outlet temperature, and synchronously issuing the cold and hot air adjustment command and the initial air volume adjustment command.

[0079] Furthermore, the execution module 15 is also used to perform the following steps: obtaining the actual measured value of the coal mill outlet temperature, comparing the actual measured value with the preset target temperature range to obtain a temperature deviation value; according to the polarity of the temperature deviation value, and with the dynamic primary air volume setting value as the total constraint, adjusting the opening ratio of the cold air regulating mechanism and the opening ratio of the hot air regulating mechanism in opposite directions to make the coal mill outlet temperature return to the target temperature range; wherein, the adjustment process of the opening ratio does not modify the value of the dynamic primary air volume setting value.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for coordinated control of coal mill pulverization based on dynamic airflow regulation, characterized in that, The method includes: Collect coal mill operating parameters, extract the cumulative running time of the grinding parts and the real-time gap value of the grinding parts, and calculate the wear stage quantification factor based on the cumulative running time of the grinding parts and the real-time gap value of the grinding parts; Based on the wear stage quantification factor, the preset basic grindability parameters and basic grinding area parameters are corrected to obtain the corrected grindability parameters and corrected grinding area parameters. Based on the corrected grindability parameters and the corrected grinding area parameters, and combined with the current coal feed rate, calculate the appropriate loading force setting value and the appropriate air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state. The dynamic primary air volume setpoint is calculated based on the adaptive air-coal ratio coefficient and the current coal feed rate. Based on the dynamic primary air volume setting value and the adaptive loading force setting value, an initial air volume adjustment command and an initial loading force adjustment command are generated and issued to maintain the coal mill outlet temperature within the preset target temperature range.

2. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 1, characterized in that, The method further includes: The actual differential pressure value during the operation of the coal mill is collected, and the actual differential pressure value is compared with the preset differential pressure target value to obtain the differential pressure deviation value. The initial air volume adjustment command is dynamically compensated based on the differential pressure deviation value, and the final primary air volume adjustment command is output. The dynamic compensation process does not change the opening ratio of the cold air conditioning mechanism and the hot air conditioning mechanism.

3. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 2, characterized in that, Dynamic compensation is performed on the initial airflow adjustment command based on the differential pressure deviation value, including: When the differential pressure deviation value is greater than the preset differential pressure fluctuation threshold, the air volume setting value in the initial air volume adjustment command is positively or negatively corrected according to the polarity of the differential pressure deviation value to obtain the final primary air volume adjustment command.

4. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 1, characterized in that, Based on the cumulative running time of the grinding element and the real-time gap value of the grinding element, a wear stage quantification factor is calculated, including: The cumulative running time of the grinding part is compared with the preset rated running time of the grinding part to obtain the time-based wear ratio. The real-time gap value of the grinding part is compared with the preset gap value of the grinding part in its new state and the preset gap value of the grinding part under extreme wear to obtain the gap wear ratio. The wear stage quantification factor is obtained by weighting the wear percentage based on the duration wear percentage and the wear percentage based on the gap wear percentage.

5. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 1, characterized in that, Based on the wear stage quantification factor, the preset basic grindability parameters and basic grinding area parameters are corrected, including: The basic wearability parameter is attenuated and corrected according to the wear stage quantification factor to obtain the corrected wearability parameter. The basic grinding area parameters are reduced and corrected based on the wear stage quantification factor to obtain the corrected grinding area parameters.

6. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 1, characterized in that, Calculate the appropriate loading force setpoint and appropriate air-coal ratio coefficient required to maintain the target pulverized coal fineness under the current wear condition, including: Read the corrected grindability parameters, the corrected grinding area parameters, and the current coal feed rate, input them into the preset output mapping table, and look up the table to obtain the reference loading force value and the reference air-coal ratio value; Read the preset target coal powder fineness threshold, input the reference loading force value and the target coal powder fineness threshold into the preset loading force correction relationship table, and look up the loading force correction ratio in the table; Multiply the reference loading force value by the loading force correction factor to obtain the adaptive loading force setting value; Read the preset coal powder uniformity index threshold, input the reference air-coal ratio value and the coal powder uniformity index threshold into the preset air-coal ratio correction relationship table, and look up the air-coal ratio correction ratio in the table; The appropriate air-coal ratio coefficient is obtained by multiplying the reference air-coal ratio value by the air-coal ratio correction factor.

7. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 1, characterized in that, Based on the adaptive air-to-coal ratio coefficient and the current coal feed rate, the dynamic primary air volume setpoint is calculated, including: Read the real-time sampled value of the current coal feed rate, and perform a moving average filter on the real-time sampled value to obtain the filtered coal feed rate; Read the adaptive air-coal ratio coefficient, multiply the adaptive air-coal ratio coefficient by the filtered coal feed rate, and obtain the theoretical primary air volume value; Read the current inlet air temperature value of the coal mill, and calculate the density compensation of the theoretical primary air volume value based on the ratio of the inlet air temperature value to the preset standard air temperature value to obtain the compensated primary air volume value. The compensated primary air volume value is determined as the dynamic primary air volume setting value.

8. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 1, characterized in that, Based on the dynamic primary air volume setting value and the adaptive loading force setting value, an initial air volume adjustment command and an initial loading force adjustment command are generated and issued, including: Based on the dynamic primary air volume setpoint, an initial air volume adjustment command is generated to control the opening of the primary air adjustment mechanism; Based on the adaptive loading force setting value, an initial loading force adjustment command for controlling the hydraulic loading mechanism is generated; Based on the dynamic primary air volume setting value, the opening ratio of the cold air regulating mechanism and the hot air regulating mechanism is calculated synchronously, and a cold and hot air regulating command for maintaining the coal mill outlet temperature is generated. The cold and hot air regulating command is then issued synchronously with the initial air volume regulating command.

9. The coal mill pulverizing collaborative control method based on dynamic air volume regulation as described in claim 8, characterized in that, Based on the dynamic primary air volume setpoint, the opening ratio of the cold air regulating mechanism and the hot air regulating mechanism is calculated synchronously, and cold and hot air regulating commands for maintaining the coal mill outlet temperature are generated, including: Obtain the actual measured value of the coal mill outlet temperature, and compare the actual measured value with the preset target temperature range to obtain the temperature deviation value; Based on the polarity of the temperature deviation value, and with the dynamic primary air volume setting value as the total constraint, the opening ratio of the cold air regulating mechanism and the opening ratio of the hot air regulating mechanism are adjusted in opposite directions to bring the coal mill outlet temperature back to the target temperature range. The adjustment process of the opening ratio does not modify the value of the dynamic primary air volume setting.

10. A coal mill pulverizing collaborative control system based on dynamic airflow regulation, characterized in that, The system is used to implement the coal mill pulverizing collaborative control method based on dynamic airflow regulation according to any one of claims 1 to 9, wherein the system comprises: The data acquisition module is used to collect the operating parameters of the coal mill, extract the cumulative running time of the grinding parts and the real-time gap value of the grinding parts, and calculate the wear stage quantification factor based on the cumulative running time of the grinding parts and the real-time gap value of the grinding parts. The correction module is used to correct the preset basic grindability parameters and basic grinding area parameters according to the wear stage quantification factor, so as to obtain the corrected grindability parameters and corrected grinding area parameters. The calculation module is used to calculate the appropriate loading force setting value and the appropriate air-coal ratio coefficient required to maintain the target coal powder fineness under the current wear state, based on the corrected grindability parameter, the corrected grinding area parameter, and the current coal feed rate. The dynamic module is used to calculate the dynamic primary air volume setpoint based on the adaptive air-coal ratio coefficient and the current coal feed rate. The execution module is used to generate and issue initial air volume adjustment commands and initial loading force adjustment commands based on the dynamic primary air volume setting value and the adaptive loading force setting value, so as to maintain the coal mill outlet temperature within the preset target temperature range.

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