A coal mill safety control system

Abstract

This invention relates to the field of coal mill control technology, specifically disclosing a coal mill safety control system, comprising: a threshold setting unit for acquiring information on the type of coal used in the coal mill, predicting the flammability coefficient of the coal based on the coal type information, and setting a safety control threshold according to the flammability coefficient; a temperature acquisition unit for acquiring the outlet temperature of the coal mill and setting a cooling coefficient based on the outlet temperature; a concentration detection unit for acquiring the carbon monoxide concentration at the outlet of the coal mill and calculating a deflagration risk coefficient based on the carbon monoxide concentration and the cooling coefficient; a cooling unit for controlling the cooling of the coal mill according to the deflagration risk coefficient; an efficiency calculation unit for detecting the outlet temperature of the coal mill after cooling control and calculating the cooling efficiency based on the outlet temperature; and a safety control unit for setting safety control measures for the coal mill based on the cooling efficiency. This invention precisely controls the outlet temperature of the coal mill, effectively preventing deflagration accidents in the coal mill.

Description

Technical Field

[0001] This application relates to the field of coal mill control technology, and more specifically, to a coal mill safety control system. Background Technology

[0002] Currently, my country's power structure still relies heavily on thermal power generation. As a crucial auxiliary equipment in thermal power generating units, the control of the outlet temperature of coal mills is vital for the economic and safe operation of these units. To further improve boiler combustion efficiency, power plants need to minimize the fineness of pulverized coal. However, the finer the pulverized coal, the larger the contact area with air, making it more susceptible to transforming into a highly flammable and explosive mixture that is extremely sensitive to open flames. If this mixture comes into contact with an open flame or if the temperature in a localized area of ​​the coal mill rises above the ignition point of the pulverized coal, an explosion can occur. This can result in equipment damage and production interruption, or even serious injuries or fatalities. Furthermore, during coal mill operation, lumpy coal undergoes an oxidation reaction with hot air during grinding, generating CO gas. Simultaneously, the heat generated further accelerates the oxidation rate of the pulverized coal, producing even more CO gas. This lowers the ignition point of combustible materials within the coal mill, potentially leading to spontaneous combustion. Current technologies for controlling the outlet temperature of coal mills often overlook the influence of carbon monoxide concentration, resulting in inaccurate detection results and contributing to deflagration accidents. Summary of the Invention

[0003] The purpose of this invention is to provide a safety control system for a coal mill, which achieves precise control of the coal mill's outlet temperature by combining the outlet temperature and carbon monoxide concentration, including:

[0004] The threshold setting unit is used to obtain information on the type of coal used in the coal mill, predict the flammability coefficient of the coal based on the coal type information, and set the safety control threshold based on the flammability coefficient of the coal.

[0005] The temperature acquisition unit is used to acquire the coal mill outlet temperature and set the cooling coefficient based on the coal mill outlet temperature.

[0006] The concentration detection unit is used to obtain the carbon monoxide concentration at the outlet of the coal mill, and to calculate the deflagration risk factor of the coal mill based on the carbon monoxide concentration and the cooling coefficient.

[0007] The cooling unit is used to control the temperature of the coal mill based on the deflagration risk factor.

[0008] The efficiency calculation unit is used to detect the coal mill outlet temperature after cooling control and calculate the cooling efficiency based on the coal mill outlet temperature.

[0009] The safety control unit is used to set safety control measures for the coal mill based on the cooling efficiency.

[0010] Furthermore, the threshold setting unit is used for:

[0011] Obtain historical data on the coal types used in coal mills and their corresponding flammability coefficients.

[0012] A coal flammability coefficient prediction model was established, and historical corresponding data were preprocessed to obtain a model training sample set.

[0013] The coal flammability coefficient prediction model is trained based on the model training sample set, and the predicted value of the coal flammability coefficient is obtained based on the training results.

[0014] Furthermore, the threshold setting unit is also used for:

[0015] Substitute the flammability coefficient of the coal type into the safety control threshold calculation formula, and calculate the safety control threshold according to the formula. The specific formula for calculating the safety control threshold is as follows:

[0016]

[0017] Where K is the security control threshold, K α F is the standard value for safety control thresholds. i F represents the flammability coefficient of the coal type. α This is the standard value for the flammability coefficient of coal.

[0018] Furthermore, the temperature acquisition unit is used for:

[0019] Calculate the outlet temperature hazard deviation, which is the difference between the current outlet temperature and the standard value of the outlet temperature;

[0020] The cooling coefficient is set according to the dangerous deviation of the outlet temperature;

[0021] If the dangerous deviation of the outlet temperature is less than the first preset threshold, then the first cooling coefficient is set as the current cooling coefficient;

[0022] If the dangerous deviation of the outlet temperature is greater than or equal to the first preset threshold, then the second cooling coefficient is set as the current cooling coefficient.

[0023] If the dangerous deviation of the outlet temperature exceeds the second preset threshold, then the third cooling coefficient is set as the current cooling coefficient.

[0024] Furthermore, the concentration detection unit is used for:

[0025] Based on the change in carbon monoxide concentration during the first preset time period, a carbon monoxide concentration change curve is plotted, and the sudden change value of carbon monoxide concentration is calculated based on the carbon monoxide concentration change curve.

[0026] Calculate the ratio of the abrupt change in carbon monoxide concentration to the standard value of the change in carbon monoxide concentration, count the maximum and minimum values ​​of the carbon monoxide concentration ratio, and normalize the carbon monoxide concentration ratio based on the maximum and minimum values.

[0027] The risk coefficient of coal mill deflagration is obtained by multiplying the cooling coefficient by the ratio of the normalized carbon monoxide concentration.

[0028] Furthermore, the concentration detection unit is also used for:

[0029] Divide the first preset time period into several sub-preset time periods and calculate the average slope of the carbon monoxide concentration change curve within each sub-preset time period.

[0030] The maximum value of the average slope of the carbon monoxide concentration change curve within a preset time period is selected, and the maximum value of the average slope is taken as the abrupt change value of carbon monoxide concentration.

[0031] Furthermore, the cooling unit is used for:

[0032] Determine whether the risk factor of deflagration in the coal mill exceeds the safety control threshold. If the risk factor of deflagration in the coal mill does not exceed the safety control threshold, then no cooling control will be implemented on the coal mill.

[0033] If the risk coefficient of deflagration in the coal mill exceeds the safety control threshold, then calculate the difference between the risk coefficient of deflagration in the coal mill and the safety control threshold.

[0034] When the difference between the coal mill deflagration risk coefficient and the safety control threshold is less than the third preset threshold, the opening of the cold air damper is adjusted to the first opening.

[0035] When the difference between the coal mill deflagration risk coefficient and the safety control threshold is greater than or equal to the third preset threshold, the opening of the cold air damper is adjusted to the second opening.

[0036] When the difference between the coal mill deflagration risk coefficient and the safety control threshold is greater than the fourth preset threshold, the opening of the cold air damper is adjusted to the third opening.

[0037] Furthermore, the efficiency calculation unit is used for:

[0038] Based on the coal mill outlet temperature after cooling control, a curve of the coal mill outlet temperature changing over time was plotted, and the coal mill outlet temperature change curve was fitted into a linear regression model of temperature change.

[0039] Set a target value for the outlet temperature, and calculate the time required for the outlet temperature to decrease to the target value based on a linear regression model of temperature change.

[0040] The cooling efficiency is calculated by using a linear regression model based on temperature changes to determine the time required for the outlet temperature to decrease to the target outlet temperature.

[0041] Furthermore, the efficiency calculation unit is also used for:

[0042] Calculate the ratio of the time required for the outlet temperature to drop to the preset target temperature value to the optimal cooling time, and use this ratio as the cooling efficiency.

[0043] Furthermore, the safety control unit is used for:

[0044] Determine whether the cooling efficiency exceeds the fifth preset threshold. If the cooling efficiency exceeds the fifth preset threshold, no safety control is required.

[0045] If the cooling efficiency does not exceed the fifth preset threshold, the difference between the cooling efficiency and the fifth preset threshold is calculated, and the safety control measures for the coal mill are set according to the difference between the cooling efficiency and the fifth preset threshold.

[0046] When the difference between the cooling efficiency and the fifth preset threshold is greater than the sixth preset threshold, the coal mill is shut down.

[0047] When the difference between the cooling efficiency and the fifth preset threshold is less than or equal to the sixth preset threshold, fire-fighting steam is injected into the coal mill for rapid cooling.

[0048] The beneficial effects of this invention are as follows:

[0049] By applying the above technical solutions, this invention combines the outlet temperature and carbon monoxide concentration when controlling the coal mill outlet temperature, and sets a safety control threshold based on coal type information. This avoids the impact of coal type differences on the calculation of deflagration risk, making the control measures more flexible, the detection results more accurate, and the outlet temperature change curve more stable. This achieves precise control of the coal mill outlet temperature, greatly reducing the probability of coal mill deflagration accidents and contributing to the safe and efficient operation of the unit. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 A schematic diagram of a coal mill safety control system proposed in an embodiment of the present invention is shown. Detailed Implementation

[0052] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0053] This application provides a coal mill safety control system, such as... Figure 1 As shown, it includes:

[0054] The system includes the following components: a threshold setting unit for acquiring coal type information, predicting the flammability coefficient of the coal based on this information, and setting a safety control threshold; a temperature acquisition unit for acquiring the coal mill outlet temperature and setting a cooling coefficient based on this temperature; a concentration detection unit for acquiring the carbon monoxide concentration at the coal mill outlet and calculating the deflagration risk coefficient based on the carbon monoxide concentration and the cooling coefficient; a cooling unit for controlling the cooling of the coal mill based on the deflagration risk coefficient; an efficiency calculation unit for detecting the coal mill outlet temperature after cooling control and calculating the cooling efficiency based on this temperature; and a safety control unit for setting safety control measures for the coal mill based on the cooling efficiency.

[0055] In this embodiment, a temperature sensor and a carbon monoxide concentration detection device are installed inside the coal mill near the outlet. The outlet temperature and CO concentration are detected by the temperature sensor and the carbon monoxide concentration detection device. The cooling unit is connected to the cold air damper of the coal mill. The cooling control is achieved by controlling the opening of the cold air damper. The safety control unit sends a signal to control the equipment to stop and the injection of fire-fighting steam.

[0056] In some embodiments of this application, the threshold setting unit is used to: obtain information on the type of coal used in the coal mill and historical corresponding data on the flammability coefficient of the corresponding coal; establish a prediction model for the flammability coefficient of the coal, preprocess the historical corresponding data, and obtain a model training sample set; train the prediction model for the flammability coefficient of the coal based on the model training sample set, and obtain the predicted value of the flammability coefficient of the coal based on the training results.

[0057] In this embodiment, a coal flammability coefficient prediction model is established by using one or more of the following algorithms: convolutional neural network, deep neural network, and genetic algorithm. Historical data is determined by the explosion sensitivity characteristics of different coal types used in the unit's operation within one year. The coal flammability coefficient represents the explosion sensitivity characteristics of the coal type. By preprocessing the historical data such as denoising, redundancy removal, and normalization, a model training sample set and a model test sample set are obtained. The coal flammability coefficient prediction model is trained based on the model training sample set and the model test sample set to achieve the purpose of predicting the coal flammability coefficient.

[0058] In some embodiments of this application, the threshold setting unit is further configured to: substitute the flammability coefficient of the coal type into the safety control threshold calculation formula, and calculate the safety control threshold according to the safety control threshold calculation formula, wherein the safety control threshold calculation formula is specifically as follows:

[0059]

[0060] Where K is the security control threshold, K α F is the standard value for safety control thresholds. i F represents the flammability coefficient of the coal type. α This is the standard value for the flammability coefficient of coal.

[0061] In this embodiment, based on the degree of deviation between the predicted flammability coefficient of coal and the standard value of the flammability coefficient of coal, a standard value of the safety control threshold is set and the safety control threshold is calculated based on the exp exponential function. This allows the setting of the safety control threshold to be adjusted according to the flammability coefficient of coal, making the threshold setting more flexible.

[0062] In some embodiments of this application, the temperature acquisition unit is used to: calculate the dangerous deviation of the outlet temperature, wherein the dangerous deviation of the outlet temperature is the difference between the current outlet temperature and the standard value of the outlet temperature; set a cooling coefficient based on the dangerous deviation of the outlet temperature; if the dangerous deviation of the outlet temperature is less than a first preset threshold, then set a first cooling coefficient as the current cooling coefficient; if the dangerous deviation of the outlet temperature is greater than or equal to the first preset threshold, then set a second cooling coefficient as the current cooling coefficient; if the dangerous deviation of the outlet temperature is greater than the second preset threshold, then set a third cooling coefficient as the current cooling coefficient.

[0063] In this embodiment, a cooling coefficient is set by calculating the dangerous deviation of the outlet temperature. The first cooling coefficient, the second cooling coefficient, and the third cooling coefficient are set sequentially from low to high. The cooling coefficient represents the dangerous level of the current coal mill outlet temperature. The higher the deviation value, the larger the set cooling coefficient.

[0064] In some embodiments of this application, the concentration detection unit is used to: plot a carbon monoxide concentration change curve based on the change value of carbon monoxide concentration in a first preset time period; calculate the carbon monoxide concentration mutation value based on the carbon monoxide concentration change curve; calculate the ratio of the carbon monoxide concentration mutation value to the standard value of carbon monoxide concentration change; statistically analyze the maximum and minimum values ​​of the carbon monoxide concentration ratio; normalize the carbon monoxide concentration ratio based on the maximum and minimum values; and multiply the cooling coefficient by the normalized carbon monoxide concentration ratio to obtain the coal mill deflagration risk coefficient.

[0065] In this embodiment, the CO concentration at the outlet of the coal mill is detected in real time by a carbon monoxide detection device, and a concentration change curve is plotted based on the change of CO concentration in the first preset time period. The standard value of the carbon monoxide concentration change is the preset allowable change in CO concentration. By calculating the product of the cooling coefficient and the normalized carbon monoxide concentration ratio, the outlet temperature and CO concentration are combined to determine the deflagration risk coefficient of the coal mill.

[0066] In some embodiments of this application, the concentration detection unit is further configured to: divide the first preset time period into several sub-preset time periods, calculate the average slope of the carbon monoxide concentration change curve within the sub-preset time periods; select the maximum value of the average slope of the carbon monoxide concentration change curve within the sub-preset time periods, and use the maximum value of the average slope as the carbon monoxide concentration mutation value.

[0067] In this embodiment, the carbon monoxide concentration change curve is divided into ten time periods by sub-preset time periods, and the average slope of the carbon monoxide concentration at both ends of the sub-preset time periods is calculated.

[0068] In some embodiments of this application, the cooling unit is used to: determine whether the deflagration risk coefficient of the coal mill exceeds the safety control threshold; if the deflagration risk coefficient of the coal mill does not exceed the safety control threshold, then no cooling control is applied to the coal mill; if the deflagration risk coefficient of the coal mill exceeds the safety control threshold, then the difference between the deflagration risk coefficient of the coal mill and the safety control threshold is calculated; when the difference between the deflagration risk coefficient of the coal mill and the safety control threshold is less than a third preset threshold, the opening of the cold air damper is adjusted to a first opening; when the difference between the deflagration risk coefficient of the coal mill and the safety control threshold is greater than or equal to the third preset threshold, the opening of the cold air damper is adjusted to a second opening; when the difference between the deflagration risk coefficient of the coal mill and the safety control threshold is greater than a fourth preset threshold, the opening of the cold air damper is adjusted to a third opening.

[0069] In this embodiment, the cooling unit sends an opening setting signal to the cold air damper. The degree of danger of the deflagration risk coefficient is determined by calculating the difference between the deflagration risk coefficient and the safety control threshold. The valve opening of the cold air damper is controlled according to the degree of danger. The higher the degree of danger, the larger the corresponding valve opening. The coal mill outlet is cooled by increasing the opening of the cold air damper.

[0070] In some embodiments of this application, the efficiency calculation unit is used to: plot a curve of the coal mill outlet temperature changing over time based on the coal mill outlet temperature after cooling control, fit the coal mill outlet temperature change curve into a linear regression model of temperature change; set a target value for the outlet temperature, calculate the time required for the outlet temperature to decrease to the target value based on the linear regression model of temperature change; and calculate the cooling efficiency based on the time required for the outlet temperature to decrease to the target value based on the linear regression model of temperature change.

[0071] In this embodiment, the outlet temperature of the coal mill after cooling control is detected in real time by a temperature sensor and a temperature change curve is plotted. A target value for the outlet temperature is preset, and the time required for the outlet temperature to drop to the target value is predicted by a linear regression model.

[0072] In some embodiments of this application, the efficiency calculation unit is further configured to: calculate the ratio of the time required for the outlet temperature to decrease to the preset temperature target value to the optimal cooling time, and use the ratio of the time required for the outlet temperature to decrease to the preset temperature target value to the optimal cooling time as the cooling efficiency.

[0073] In this embodiment, the optimal cooling time is determined based on the unit's operating experience. The cooling efficiency is determined by the ratio of the time required for the outlet temperature to drop to the preset target temperature value to the optimal cooling time, thus obtaining the effect of the cold air damper opening on the outlet temperature adjustment.

[0074] In some embodiments of this application, the safety control unit is used to: determine whether the cooling efficiency exceeds a fifth preset threshold; if the cooling efficiency exceeds the fifth preset threshold, no safety control is required; if the cooling efficiency does not exceed the fifth preset threshold, calculate the difference between the cooling efficiency and the fifth preset threshold, and set safety control measures for the coal mill based on the difference between the cooling efficiency and the fifth preset threshold; when the difference between the cooling efficiency and the fifth preset threshold is greater than a sixth preset threshold, shut down the coal mill; when the difference between the cooling efficiency and the fifth preset threshold is less than or equal to the sixth preset threshold, spray fire-fighting steam into the coal mill for rapid cooling.

[0075] In this embodiment, the cooling efficiency is determined by the fifth preset threshold. When the safety control unit detects that the cooling efficiency does not exceed the fifth preset threshold, the degree of deviation of the cooling efficiency is calculated by the difference between the cooling efficiency and the fifth preset threshold. If the degree of deviation is greater than the sixth preset threshold, it indicates that the cooling efficiency is not high, and only a shutdown signal is issued to shut down the coal mill. If the degree of deviation is less than or equal to the sixth preset threshold, it indicates that the cooling efficiency is too low, and the coal mill may explode at any time. At this time, fire-fighting steam should be injected into the coal mill to achieve rapid cooling on the basis of shutdown.

[0076] To further illustrate the technical concept of this invention, the technical solution of this invention will now be described in conjunction with specific application scenarios.

[0077] By applying the above technical solutions, this invention establishes a coal flammability coefficient prediction model to predict the corresponding coal flammability coefficient based on the coal type information of the coal mill, and sets the safety control threshold of the coal mill based on the coal flammability coefficient. A cooling coefficient is selected by detecting the outlet temperature. The outlet CO concentration is monitored in real time, a CO concentration change curve is plotted, and the concentration change abrupt value is calculated. The ratio of the concentration change abrupt value to the standard value is normalized and multiplied by the cooling coefficient to obtain the deflagration risk coefficient. The opening degree of the coal mill's cold air damper is set by comparing the deflagration risk coefficient with the safety control threshold to reduce the coal mill outlet temperature. The outlet temperature change of the coal mill is monitored in real time, and the temperature change curve is fitted to a linear regression model to calculate the coal mill cooling efficiency. The coal mill cooling efficiency is used to determine whether to shut down the coal mill or use fire-fighting steam cooling to prevent coal mill deflagration accidents.

[0078] Through the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented in hardware or by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) and includes several instructions to cause a computer device (such as a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A safety control system for a coal mill, characterized in that, include: The threshold setting unit is used to obtain information on the type of coal used in the coal mill, predict the flammability coefficient of the coal based on the coal type information, and set the safety control threshold based on the flammability coefficient of the coal. The temperature acquisition unit is used to acquire the coal mill outlet temperature and set the cooling coefficient based on the coal mill outlet temperature. The concentration detection unit is used to obtain the carbon monoxide concentration at the outlet of the coal mill, and to calculate the deflagration risk factor of the coal mill based on the carbon monoxide concentration and the cooling coefficient. The cooling unit is used to control the temperature of the coal mill based on the deflagration risk factor. The efficiency calculation unit is used to detect the coal mill outlet temperature after cooling control and calculate the cooling efficiency based on the coal mill outlet temperature. The safety control unit is used to set safety control measures for the coal mill based on the cooling efficiency. The temperature acquisition unit is used for: Calculate the outlet temperature hazard deviation, which is the difference between the current outlet temperature and the standard value of the outlet temperature; The cooling coefficient is set according to the dangerous deviation of the outlet temperature; If the dangerous deviation of the outlet temperature is less than the first preset threshold, then the first cooling coefficient is set as the current cooling coefficient; If the dangerous deviation of the outlet temperature is greater than or equal to the first preset threshold and the dangerous deviation of the outlet temperature is less than or equal to the second preset threshold, then the second cooling coefficient is set as the current cooling coefficient. If the dangerous deviation of the outlet temperature exceeds the second preset threshold, then the third cooling coefficient is set as the current cooling coefficient.

2. The coal mill safety control system as described in claim 1, characterized in that, The threshold setting unit is used for: Obtain historical data on the coal types used in coal mills and their corresponding flammability coefficients. A coal flammability coefficient prediction model was established, and historical corresponding data were preprocessed to obtain a model training sample set. The coal flammability coefficient prediction model is trained based on the model training sample set, and the predicted value of the coal flammability coefficient is obtained based on the training results.

3. The coal mill safety control system as described in claim 2, characterized in that, The threshold setting unit is also used for: Substitute the flammability coefficient of the coal type into the safety control threshold calculation formula, and calculate the safety control threshold according to the formula. The specific formula for calculating the safety control threshold is as follows: in, K For safety control thresholds, This is the standard value for safety control thresholds. The flammability coefficient of the coal type, This is the standard value for the flammability coefficient of coal.

4. The coal mill safety control system as described in claim 1, characterized in that, The concentration detection unit is used for: Based on the change in carbon monoxide concentration during the first preset time period, a carbon monoxide concentration change curve is plotted, and the sudden change value of carbon monoxide concentration is calculated based on the carbon monoxide concentration change curve. Calculate the ratio of the abrupt change in carbon monoxide concentration to the standard value of the change in carbon monoxide concentration, count the maximum and minimum values ​​of the carbon monoxide concentration ratio, and normalize the carbon monoxide concentration ratio based on the maximum and minimum values. The risk coefficient of coal mill deflagration is obtained by multiplying the cooling coefficient by the ratio of the normalized carbon monoxide concentration.

5. The coal mill safety control system as described in claim 4, characterized in that, The concentration detection unit is also used for: Divide the first preset time period into several sub-preset time periods and calculate the average slope of the carbon monoxide concentration change curve within each sub-preset time period. The maximum value of the average slope of the carbon monoxide concentration change curve within a preset time period is selected, and the maximum value of the average slope is taken as the abrupt change value of carbon monoxide concentration.

6. The coal mill safety control system as described in claim 1, characterized in that, The cooling unit is used for: Determine whether the risk factor of deflagration in the coal mill exceeds the safety control threshold. If the risk factor of deflagration in the coal mill does not exceed the safety control threshold, then no cooling control will be implemented on the coal mill. If the risk coefficient of deflagration in the coal mill exceeds the safety control threshold, then calculate the difference between the risk coefficient of deflagration in the coal mill and the safety control threshold. When the difference between the coal mill deflagration risk coefficient and the safety control threshold is less than the third preset threshold, the opening of the cold air damper is adjusted to the first opening. When the difference between the coal mill deflagration risk coefficient and the safety control threshold is greater than or equal to the third preset threshold, and the difference between the coal mill deflagration risk coefficient and the safety control threshold is less than or equal to the fourth preset threshold, the opening of the cold air damper is adjusted to the second opening. When the difference between the coal mill deflagration risk coefficient and the safety control threshold is greater than the fourth preset threshold, the opening of the cold air damper is adjusted to the third opening.

7. The coal mill safety control system as described in claim 1, characterized in that, The efficiency calculation unit is used for: Based on the coal mill outlet temperature after cooling control, a curve of the coal mill outlet temperature changing over time was plotted, and the coal mill outlet temperature change curve was fitted into a linear regression model of temperature change. Set a target value for the outlet temperature, and calculate the time required for the outlet temperature to decrease to the target value based on a linear regression model of temperature change. The cooling efficiency is calculated by using a linear regression model based on temperature changes to determine the time required for the outlet temperature to decrease to the target outlet temperature.

8. The coal mill safety control system as described in claim 7, characterized in that, The efficiency calculation unit is also used for: Calculate the ratio of the time required for the outlet temperature to drop to the preset target temperature value to the optimal cooling time, and use this ratio as the cooling efficiency.

9. The coal mill safety control system as described in claim 1, characterized in that, The safety control unit is used for: Determine whether the cooling efficiency exceeds the fifth preset threshold. If the cooling efficiency exceeds the fifth preset threshold, no safety control is required. If the cooling efficiency does not exceed the fifth preset threshold, the difference between the cooling efficiency and the fifth preset threshold is calculated, and the safety control measures for the coal mill are set according to the difference between the cooling efficiency and the fifth preset threshold. When the difference between the cooling efficiency and the fifth preset threshold is greater than the sixth preset threshold, the coal mill is shut down. When the difference between the cooling efficiency and the fifth preset threshold is less than or equal to the sixth preset threshold, fire-fighting steam is injected into the coal mill for rapid cooling.

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