A fully automatic control system for pulverized coal preparation equipment

Abstract

This invention provides a fully automatic control system for pulverized coal preparation equipment, comprising: an automatic combustion control unit for the flue gas furnace, a furnace pressure stabilization and mill outlet temperature limiting control unit, a mill outlet temperature control unit, and a start-up and shutdown sequence control unit for the pulverizing equipment. This system is a fully automatic control system capable of automatically starting and stopping the entire system, controlling production, and automatically adjusting the mill outlet temperature and flue gas furnace pressure. It enables fully automatic control of the pulverized coal preparation process, thereby significantly reducing the workload of operators and improving the safety level of the production process.

Description

Technical Field

[0001] This invention mainly relates to the technical field of coal powder preparation, specifically a fully automatic control system for coal powder preparation equipment. Background Technology

[0002] Pulverized coal injection into blast furnaces is a crucial method for saving coke, reducing ironmaking and smelting costs, and minimizing environmental pollution from coking. Pulverized coal preparation is a key production step in blast furnace pulverized coal injection. Currently, the main equipment for pulverized coal preparation includes a raw coal yard, raw coal bunker, flue gas furnace, mill, baghouse, and pulverized coal silo. The raw coal yard supplies material to the raw coal bunker via conveyor belts and iron removers. The raw coal bunker is equipped with air cannons, and the flue gas furnace is controlled by a variable frequency combustion fan and corresponding valves. Currently, the main operation method for pulverized coal preparation is computer-controlled parameter monitoring and manual remote control via keyboard. Starting and stopping the system and during production require operators to follow the operating procedures step-by-step based on the actual parameters displayed on the screen, resulting in a heavy workload and high demands on responsibility. Incorrect operation can lead to flue gas furnace flameout, excessive mill outlet temperature, and internal mill combustion, among other malfunctions and safety issues. Therefore, achieving fully automated control of pulverized coal production has always been a pressing need for personnel in the pulverized coal preparation process. Summary of the Invention

[0003] To address the shortcomings of current technologies, this invention, based on existing technologies and practical applications, provides a fully automatic control system for pulverized coal preparation equipment. This invention is a fully automatic control system that can automatically start and stop the entire system, control production, and automatically adjust the mill outlet temperature and flue gas furnace pressure. It can achieve fully automatic control of the pulverized coal preparation process, thereby greatly reducing the workload of operators and improving the safety level of the process.

[0004] The technical solution of the present invention is as follows:

[0005] A fully automatic control system for a pulverized coal preparation equipment includes: an automatic combustion control unit for a flue gas furnace, configured to enable the flue gas furnace to enter a heat preservation combustion stage in a non-pulverizing state, to enable the flue gas furnace to enter a heat delivery combustion stage in a pulverizing state, to stabilize the furnace temperature at the heat preservation temperature in the heat preservation combustion stage, and to stabilize the furnace temperature at the heat delivery temperature in the heat delivery combustion stage.

[0006] The furnace pressure stabilization and mill outlet temperature control unit is configured to automatically stabilize the flue gas furnace pressure within the set pressure range and control the mill outlet temperature within a safe range during equipment start-up and shutdown.

[0007] The mill outlet temperature control unit is configured to automatically adjust the mill outlet temperature when it exceeds the set temperature during production, and to control the equipment to stop if the mill outlet temperature is still higher than the upper temperature limit after adjustment.

[0008] The start-stop sequence control unit for the pulverizing equipment is configured to call the automatic combustion control unit of the flue gas furnace, the furnace pressure stabilization and mill outlet temperature limiting control unit, and the mill outlet temperature control unit when executing start-stop control, so as to control the equipment to start and stop in the set start-stop sequence.

[0009] Furthermore, the automatic combustion control unit of the flue gas furnace includes a combustible gas regulating valve, a combustion-supporting fan, furnace temperature data, furnace pressure data, combustion-supporting air flow data, and combustible gas flow data;

[0010] During the heat preservation and combustion stage, the set values ​​of the combustion air flow and combustible gas flow are automatically replaced with the empirical values ​​of the heat preservation state. During the heat supply and combustion stage, the set values ​​of the combustion air flow and combustible gas flow are automatically replaced with the empirical values ​​of the heat supply. When the furnace temperature exceeds the heat supply temperature, the combustible gas regulating valve and the speed of the combustion air blower are adjusted by PID to stabilize the furnace temperature at the heat supply temperature.

[0011] Furthermore, during the combustion heating stage, the PID control method is as follows:

[0012] When the furnace temperature is at T LTSD2 -ΔT1<T LT <T LTSD2 When +ΔT1, no adjustment is made;

[0013] When the furnace temperature is at T LT >T LTSD2 +ΔT1 or T LT <T LTSD2 At -ΔT1, a deviation value ΔF is added or subtracted from the current combustible gas flow rate. The combustion air flow rate changes synchronously with the combustion ratio, achieving a 5-second adjustment cycle. When the temperature rises, the combustion amount is reduced by a deviation value ΔF, and when the temperature falls, the combustion amount is increased by a deviation value ΔF.

[0014] Where ΔT1 is the temperature adjustment dead zone deviation value, T LTSD2 T is the setpoint for the furnace heating temperature. LT This refers to the furnace temperature.

[0015] Furthermore, the furnace pressure stabilization and mill outlet temperature control unit includes the mill inlet regulating valve, circulating air valve, mill outlet temperature data, and furnace pressure data. The control methods during equipment start-up and shutdown are as follows:

[0016] When the furnace pressure P LT When P > -10Pa, the circulating air valve is closed by 1%; when P LT <-100Pa or mill outlet temperature T MCWhen the temperature is above 65℃, the mill inlet regulating valve is closed by 1% to ensure that the flue gas furnace pressure remains stable between -100 and -10 Pa during equipment startup or shutdown, thus controlling and limiting the mill outlet temperature to below 65℃.

[0017] Furthermore, the mill outlet temperature control unit includes a sealed coal feeder, a mill inlet regulating valve, a circulating air regulating valve, flue gas furnace temperature data, mill differential pressure data, and mill outlet temperature data. Its method for controlling the mill outlet temperature is as follows:

[0018] When the mill outlet temperature exceeds the set temperature ± deviation value, the coal feed rate will be automatically increased or decreased. If the increase or decrease in the coal feed rate cannot meet the temperature control requirements, the valve positions of the mill inlet regulating valve and the circulating air regulating valve will be adjusted. If the temperature control requirements still cannot be met, the flue gas furnace temperature will be automatically adjusted. If the mill outlet temperature still exceeds the set upper limit after the above adjustments, the equipment will automatically shut down for protection.

[0019] Furthermore, the specific control method of the mill outlet temperature control unit is as follows: it is adjusted every 10 seconds. When the 10-second pulse is triggered, the mill outlet temperature T is first determined. MC Is it in T? SD -ΔT<T MC <T SD Within the range of +ΔT, where T SD The setpoint for the mill outlet temperature is ΔT, where ΔT is the temperature deviation. If it is within the above range, the setpoint for the coal feeder flow rate is L. SD and the setpoint T for the flue gas furnace heating temperature LTSD2 No adjustments will be made. If the area is not within the above range, adjust as follows:

[0020] 2) When L is satisfied simultaneously SJ <L SX ΔP MJ <5 kPa, L SJ1 >L SJ3 At that time, the following adjustments will be made:

[0021] 1.1 If T is satisfied SD +ΔT<T MC For conditions <76℃, the setpoint L for the coal feeder flow rate is... SD An additional feeder flow rate adjustment constant ΔL needs to be added;

[0022] 1.2) If 76℃ < T MC For conditions <78℃, the setpoint L for the coal feeder flow rate is... SD It is necessary to increase the coal feeder flow rate adjustment constant ΔL by 2 times and activate the air cannon once.

[0023] 1.3) If T is satisfied MCFor conditions >78℃, the setpoint L for the coal feeder flow rate is... SD It is necessary to increase the coal feeder flow rate adjustment constant ΔL by 4 times and activate the air cannon twice at an interval of 10 seconds.

[0024] 1.4) If T is satisfied MC >78℃ or L SJ >L SX or ΔP MJ >5KPa: The mill inlet regulating valve will be closed by 1% and the circulating air valve will be opened by 1%. If the opening of the mill inlet regulating valve is <50% and the opening of the circulating air valve is >65%, the furnace heating temperature setting will be adjusted once to reduce the mill inlet temperature.

[0025] 1.5) If T is satisfied MC If the temperature exceeds 85℃, the equipment will initiate an automatic protection shutdown procedure.

[0026] 2 When T is satisfied simultaneously MC <T SD -ΔT、L SJ1 <L SJ3 At that time, the following adjustments will be made:

[0027] 2.1 As L SJ >L XX The setpoint L for the coal feeder flow rate SD The feeder flow rate adjustment constant ΔL needs to be reduced once;

[0028] 2.2 such as L SJ <L XX The system will automatically adjust the mill inlet regulating valve by increasing the valve position by 1% and the circulating air valve by decreasing the valve position by 1%.

[0029] 2.3 If the mill inlet regulating valve is open >65% and the circulating air valve is open <50%, it is determined that the flue gas furnace has a combustion fault, and the alarm will be triggered and the operation will switch to manual mode.

[0030] The above, L SJ For coal feeder flow rate, L SX For the upper limit of the coal feeder flow rate, ΔP MJ For mill pressure differential value, L XX For the lower limit of coal feeder flow rate, L SJ1 For the instantaneous coal quantity with a 1-second lag, L is a temporary variable. SJ3 This is a temporary variable for the instantaneous coal quantity with a 3-second lag.

[0031] Furthermore, the start-up and shutdown sequence control unit of the pulverizing equipment controls the equipment to start up in the following manner:

[0032] 1. Determine that all equipment is in a normal startable state, start the bag filter box back-flushing system, delay the start of the pulverized coal vibrating screen, delay the start of the airlock ash discharge valve, open the mill emergency nitrogen charging valve, start the mill separator to run at >40HZ, start the main induced draft fan to run at >15HZ, set the mill inlet regulating valve and circulating air valve to 20%, and start the flue gas furnace pressure stabilization and mill outlet temperature limiting programs;

[0033] 2. When -100Pa < P LT <-10Pa+T MC After the temperature drops below 65℃, the interlocking protection procedure is activated, where P LT T is the furnace pressure. MC This refers to the mill outlet temperature.

[0034] The main induced draft fan speeds up to 35Hz, automatically adjusting to meet the condition of -100Pa < P. LT <-10Pa+T MC After the temperature drops below 65℃, the main induced draft fan speed is increased to 45Hz, and then adjusted to ensure that -100Pa < P is met. LT <-10Pa+T MC After reaching a temperature of <65℃, warm up the mill for several minutes under this condition, then start the lubrication station, start the hydraulic station and lift the grinding rollers, and start the mill motor;

[0035] 4. Adjust the actual opening of the mill inlet regulating valve and the circulating air valve by +20%, and determine if -100Pa < P. LT <-10Pa+T MC After the temperature drops below 65℃, the actual opening value of the mill inlet regulating valve and the circulating air valve is increased by 20%. After the valve position is in place, under the adjustment of the automatic pressure stabilization of the flue gas furnace, the flue gas furnace vent valve is gradually adjusted from 100%, 65%, 30%, 0% until it is closed.

[0036] 5 when T MC When the temperature exceeds 65℃, the flue gas furnace heating program is initiated; when T... MC When the temperature is above 70℃, start the coal feeder belt and cleaning chain, and set the coal feeder flow rate to L. SD After PID control brings the actual flow rate to approximately the set value, the grinding roller is lowered and pressurized to start grinding after a 5-second delay. The automatic control program for mill outlet temperature and the flue gas furnace pressure stabilization program are then activated. While adjusting the outlet temperature, the automatic control program for mill outlet temperature automatically increases the coal feeder flow rate to near the hourly output.

[0037] Furthermore, the start-up and shutdown sequence control unit of the powder-making equipment controls the equipment to shut down in the following manner:

[0038] When the pulverized coal silo level exceeds the upper limit, the automatic shutdown procedure is initiated after a 40-second delay, and the flue gas furnace enters the heat preservation program. The mill outlet temperature T... MC With flue gas furnace temperature TLT As the temperature decreases, the program enters a 5-second interval for flue gas furnace pressure stabilization and mill outlet temperature limit control.

[0039] First, collect the hysteresis T. MC Temperature sampling value T2 at 5-second intervals; when T does not meet the requirements. MC <T2-ΔT but satisfies T2-ΔT<T MC <T2+ΔT condition, where ΔT is the temperature deviation value, adjust the opening of the mill inlet regulating valve and the circulating air valve to decrease by 1%; when T is not satisfied MC <T2-ΔT condition but satisfy T MC When the condition is greater than T2+ΔT, adjusting the feeder flow rate setpoint increases the feeder flow rate adjustment constant ΔL, thus promoting T. MC Decrease until T MC The condition <T2-ΔT holds true;

[0040] When T is satisfied MC When the condition <T2-ΔT is met, the feeder flow rate setpoint is reduced by the flow rate adjustment constant ΔL once, and then adjusted again after a 5-second interval, until the shutdown safety condition (feeder flow rate L) is met. SJ ≤20% of the measuring range + mill outlet temperature T MC <60℃;

[0041] After the shutdown safety conditions are met, sequentially fully open the cold air valve, fully open the flue gas furnace vent valve, close the circulating air valve, close the mill inlet regulating valve, and when the mill current reaches near the no-load value, raise the grinding rollers, stop the mill motor, stop the hydraulic station, and stop the main induced draft fan. Wait until the main induced draft fan flow rate is <1000 Nm³. 3 / h, the mill separator stops, after a 200-second delay, the bag filter backflushing system stops, the airlock ash discharge valve stops, the coal powder vibrating screen stops, the cold air valve closes, the main exhaust valve closes, the mill emergency nitrogen charging starts and closes after 2 minutes, and the system shutdown is complete.

[0042] The beneficial effects of this invention are:

[0043] 1. The control system of this invention can utilize existing PLC control systems, leveraging relevant equipment and detection parameters in the pulverized coal preparation process. Through years of accumulated production operation experience and exploration and practice in production process control, a process control flow has been developed, encompassing automatic combustion of the flue gas furnace, automatic adjustment of the mill outlet temperature, one-button sequential start-up and shutdown of the pulverizing system, segmented valve position control for furnace pressure stabilization and mill outlet temperature limiting during start-up and shutdown, and segmented control of flue gas velocity. By developing calculation and control programs that conform to the actual process, fully automatic control of the pulverized coal preparation process can be achieved, thereby greatly reducing the workload of on-site operators and improving the safety level of process production.

[0044] 2. The control system of the present invention adopts different adjustment modes for different control parameters based on their different characteristics. For example, parameters such as gas flow rate and coal feeder flow rate, which can respond quickly, adopt PID regulation. However, furnace temperature and mill outlet temperature, due to their large lag and fluctuation patterns within the range of the set value, adopt an approximate sine wave positive and negative region upper and lower edge partition control approach to reduce the oscillation amplitude of the adjustment and avoid overshoot.

[0045] 3. The automatic combustion control unit of the flue gas furnace in the control system of this invention automatically adjusts the ratio of combustible gas and combustion air according to the oxygen and CO content in the flue gas after combustion; during system startup, continuous furnace pressure regulation and mill outlet temperature limit control are adopted at different stages of valve position increase and flow rate acceleration; the automatic control program for mill outlet temperature adopts a hierarchical control mode of coal feed rate regulation (main adjustment), valve position regulation of mill inlet valve and circulating air valve (secondary adjustment), and furnace temperature regulation (auxiliary adjustment); the start-up and shutdown logic control sequence of the pulverizing system can ensure that the pulverized coal preparation system can reliably and safely start up the system equipment one by one and enter the normal production state; the shutdown program can ensure that the pulverized coal preparation system can reliably and safely stop the system equipment one by one and enter the shutdown state; the interlock protection program can interlock and protect the shutdown of the entire pulverizing system when key equipment or process parameters are seriously abnormal. Attached Figure Description

[0046] Appendix Figure 1 This is a schematic diagram of the control principle of the present invention. Detailed Implementation

[0047] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0048] This embodiment provides a fully automatic control system for pulverized coal preparation equipment. Utilizing a PLC control system, based on the process equipment configuration and process control principles, it has developed segmented and functional control for automatic combustion of the flue gas furnace, furnace pressure stabilization and mill outlet temperature limiting during system start-up and shutdown, automatic adjustment of mill outlet temperature, start-up and shutdown sequence of the pulverizing system, and interlock protection. The above four control units are organically combined to achieve fully automatic control of the pulverized coal preparation process, replacing the current manual operation and improving the operational level and safety reliability of the pulverized coal preparation process.

[0049] The control system of this invention mainly includes an automatic combustion control unit for the flue gas furnace, a furnace pressure stabilization and mill outlet temperature limiting control unit, a mill outlet temperature control unit, a pulverizing equipment start-up and shutdown sequence control unit, and an interlocking protection logic control unit. The automatic combustion control unit for the flue gas furnace enables automatic operation in both heat preservation and heating states; the furnace pressure stabilization and mill outlet temperature limiting control unit ensures stable combustion in the flue gas furnace and prevents the mill outlet temperature from exceeding limits during production start-up and shutdown; the mill outlet temperature control unit enables automatic adjustment of coal quantity, valve fine-tuning, and flue gas furnace temperature fine-tuning during production; the pulverizing equipment start-up and shutdown sequence control unit, by invoking the above units, achieves safe and reliable automatic start-up and shutdown of the entire production process; the interlocking protection logic control unit ensures the safe shutdown of the system in case of equipment failure or extreme abnormalities in process parameters. The following is a detailed description of each of the above control units.

[0050] Automatic combustion control unit for flue gas furnace:

[0051] The common states of a flue gas furnace in pulverized coal preparation processes are: shutdown, heat preservation, and heat supply. The set temperatures during heat preservation and heat supply can be controlled within the most economical range. The hardware of the automatic combustion control unit for the flue gas furnace in this embodiment mainly includes a variable frequency combustion fan, a combustible gas pipeline regulating valve and shut-off valve, a chimney vent valve, and furnace temperature, pressure, oxygen and CO content, combustible gas flow rate, pressure, and temperature detection equipment. The software mainly consists of two programs: heat preservation combustion and heat supply combustion.

[0052] During the heat preservation combustion phase, when the system program enters the heat preservation combustion phase, it automatically replaces the set values ​​of the combustion air flow and combustible gas flow with the empirical values ​​of the heat preservation state (preliminary debugging and experimental values) to keep the furnace temperature basically stable at 400-450℃. It also assists in the constant air conditioning combustible gas combustion control based on the flue gas content value to keep the flame running with the lowest possible combustible gas consumption.

[0053] When the combustion is in the pulverizing state, the system program automatically replaces the set values ​​of the combustion air flow rate and the combustible gas flow rate with the empirical values ​​of the combustion air flow rate (preliminary debugging and experimental values) to gradually bring the furnace temperature closer to about 950℃. This is assisted by constant air conditioning combustible gas combustion control based on the flue gas content value. When the furnace temperature exceeds the range of 950±10℃, the optimal flow ratio of combustible gas and combustion air is adjusted by automatically adjusting the combustible gas regulating valve and the speed of the combustion air blower, so that the furnace temperature is stabilized within the range of 950±10℃.

[0054] The process equipment and control parameters of this control procedure are controlled by the combustible gas regulating valve K. KR Shut-off valve K QD Combustion fan S ZR Chimney vent valve K FS Flame detection HY1 Furnace temperature T LT Furnace pressure P LT Oxygen content in the furnace 2 LT Furnace CO content LT Composition. This control unit can operate in two states: heat preservation and heat supply, depending on the production situation.

[0055] During heat preservation operation, the flow rate only needs to be adjusted to near the commonly used low empirical value. This can be aided by detecting the combustion gas content to adjust to the optimal combustion ratio, ensuring economical combustion at low flow rates. During heat supply, the furnace temperature and combustion conditions need to be adjusted: T is set according to the furnace temperature. LTSD2 The value is automatically coarsely adjusted to the commonly used air-fuel flow rate value and the empirically adjusted value, which assists in adjusting the combustion gas content (O2). 2 LT CO LT The detection is performed, and the combustible gas regulating valve K is adjusted via PID control. KR Opening degree and combustion fan S ZR Rotation speed ensures that combustion in the furnace is at the optimal combustion ratio.

[0056] When the furnace temperature is at T LTSD2 -ΔT1<T LT <T LTSD2 +ΔT1, when ΔT1 is the dead zone value, no adjustment is made; when the furnace temperature is at T LT >T LTSD2 +ΔT1 or T LT <T LTSD2 At -ΔT1, respectively, at the current combustible gas flow rate F KES Based on the above, reduce or increase by a deviation value ΔF, the combustion air flow value F ZRS Based on the synchronous change of the combustion ratio, an adjustable time period of 5 seconds can be achieved. When the temperature rises, the combustion amount decreases by ΔF once, and when the temperature falls, the combustion amount increases by ΔF once, so that the furnace temperature is stabilized within the deviation range of the set value.

[0057] Furnace pressure stabilization and mill outlet temperature control unit:

[0058] During system start-up, shutdown, and normal production, the furnace pressure of the flue gas furnace can be automatically stabilized within the range of -100 to -10 Pa, which can prevent the flue gas furnace from shutting down or emitting smoke; the mill outlet temperature is controlled within a safe value, which can effectively prevent the occurrence of system deflagration safety accidents.

[0059] The process equipment and control parameters of this control unit are controlled by the mill inlet regulating valve K. MR Circulating air valve K XH Mill outlet temperature T MC Furnace pressure PLT Composition. During system startup and shutdown, when P LT When the pressure is >-10Pa, the circulating air valve K XH Close the valve position by 1%; when P LT <-100Pa or T MC When the temperature is >65℃, the mill inlet regulating valve K MR Close the valve by 1%. This is to ensure that the flue gas furnace pressure P remains constant during system startup or shutdown. LT The temperature is kept consistently between -100°C and -10°C to prevent dangerous phenomena such as flue gas furnace flameout or flame ejection; the mill outlet temperature (T) is limited. MC Temperatures below 65℃ are necessary to ensure safety during system start-up and shutdown.

[0060] Mill outlet temperature control unit:

[0061] The system mainly consists of three functions: coal feed rate regulation (primary regulation), mill inlet valve and circulating air valve position regulation (secondary regulation), and furnace temperature regulation (auxiliary regulation). When the mill outlet temperature exceeds the set temperature ± deviation value, the coal feed rate is automatically increased or decreased. If the increase or decrease in coal feed rate cannot meet the temperature control requirements, the valve positions of the mill inlet regulating valve and circulating air regulating valve are adjusted. If the temperature control requirements are still not met, the flue gas furnace temperature is automatically adjusted. Regarding the upper temperature limit, if the mill outlet temperature still exceeds the allowable upper limit after the above adjustments, it indicates that the system has an abnormal situation, and the system will automatically shut down for protection.

[0062] The process equipment and control parameters of this control unit are controlled by the mill inlet regulating valve K. MR Circulating air valve K XH Coal feeder flow rate setpoint L SD Mill outlet temperature T MC Mill outlet temperature setpoint T SD Temperature deviation value ΔT, coal feeder flow rate setpoint L SD Coal feeder flow measurement value L SJ Upper limit of coal feeder flow rate L SX Lower limit of coal feeder flow rate L XX , Coal feeder flow rate adjustment constant ΔL, Mill pressure difference ΔP MJ This scheme consists of [various components]. It adjusts every 10 seconds. When the 10-second pulse is triggered, the current temperature T is first determined. MC Is the value in this T? SD- ΔT<T MC <T SD Within +ΔT range? If within the above range, the feeder flow setpoint L SD and flue gas furnace temperature setpoint T LTSD2 No adjustments will be made. If the item is not within the above range:

[0063] When the coal feeder flow rate L is simultaneously satisfied SJ < Upper limit of coal feeder flow rate L SX + Mill pressure difference ΔPMJ < 5KPa and instantaneous coal quantity temporary variable L SJ1 >Instantaneous coal quantity temporary variable L SJ3 When the parameters are at the rising edge of the positive zone of the control curve, the program will proceed with the following adjustments:

[0064] 1.1) If T is satisfied SD +ΔT<T MC For conditions <76℃, the feeder flow rate setpoint needs to be increased by one feeder flow rate adjustment constant ΔL;

[0065] 1.2) If 76℃ < T MC If the temperature is less than 78℃, the feeder flow rate setting needs to be increased by twice the feeder flow rate adjustment constant ΔL, and the air cannon needs to be activated once.

[0066] 1.3) If T is satisfied MC For conditions >78℃, the feeder flow rate setting needs to be increased by 4 times the feeder flow rate adjustment constant ΔL, and the air cannon needs to be activated twice at 10-second intervals.

[0067] 1.4) If T is satisfied MC >78℃ or coal feeder flow rate (L) SJ > Upper limit of coal feeder flow rate L SX Or the mill pressure difference value ΔP MJ If the pressure is greater than 5 kPa, the opening of the mill inlet regulating valve will be automatically adjusted to K. MR -1%, circulating air valve opening degree is K XH +1%; if the valve opening is at K MR <50%, K XH If the value is greater than 65%, then the flue gas furnace temperature setpoint should be adjusted once to T. LTSD2 -100℃, to reduce the mill inlet temperature;

[0068] 1.5) If T is satisfied MC If the temperature exceeds 85℃, the system will initiate an automatic protection shutdown procedure.

[0069] 2) When T is satisfied simultaneously MC <T SD -ΔT and instantaneous coal quantity temporary variable L SJ1 <Instantaneous Coal Quantity Temporary Variable L> SJ3 When the parameters are at the falling edge of the negative region of the control curve, the program will proceed with the following adjustments:

[0070] 2.1) For example, the coal feeder flow rate L SJ >Lower limit of coal feeder flow rate L XXIf so, the feeder flow rate setpoint needs to be reduced by one feeder flow rate adjustment constant ΔL;

[0071] 2.2) For example, the coal feeder flow rate L SJ <Lower limit of coal feeder flow rate L XX Then the opening degree of the mill inlet regulating valve will be automatically adjusted to K. MR +1%, circulating air valve opening is K XH -1% to increase the mill inlet temperature;

[0072] 2.3) If the valve opening is already at K MR >65%, K XH If the rate is less than 50%, it is determined that there is a furnace burnout fault in the flue gas furnace, and the alarm will be triggered to switch to manual operation.

[0073] Flour mill start / stop sequence control unit:

[0074] The startup sequence program ensures that the pulverized coal preparation system can reliably and safely start up each piece of equipment and enter normal production; the shutdown program ensures that the pulverized coal preparation system can reliably and safely stop each piece of equipment and enter shutdown state.

[0075] During start-up and shutdown, the aforementioned control unit was invoked to participate in the control. After startup, the mill outlet temperature automatic control unit and the flue gas furnace automatic combustion control unit mainly maintain stable production.

[0076] In this control unit, the automatic start-up sequence is as follows: determining that the flue gas furnace is in normal insulation mode + raw coal bunker material level W. YM Higher than the low material level (if lower than the low material level, the automatic feeding program will run) + coal powder silo material level W F <50% upper limit, given main exhaust valve K ZP =40%, circulating air valve K XH =0%, Mill inlet regulating valve K MR =0%, flue gas furnace vent valve K FS =100%, after all conditions are met, start the bag filter backflushing system, delay the start of the pulverized coal vibrating screen, delay the start of the airlock ash discharge valve, open the mill emergency nitrogen charging valve (stop after 3 minutes), start the mill separator to run at >40HZ, start the main induced draft fan to run at >15HZ, and adjust the mill inlet K. MR and circulating air K XH Set all parameters to 20% and initiate the flue gas furnace pressure stabilization and milling temperature limiting programs.

[0077] When -100Pa < P LT <-10Pa+T MC When the temperature drops below 65℃, the system engages its interlock protection program; the main induced draft fan speeds up to 35Hz and automatically adjusts to meet the condition of -100Pa < P. LT<-10Pa+T MC After the temperature drops below 65℃, the main induced draft fan speed is increased to 45Hz, and then adjusted to ensure that -100Pa < P is met. LT <-10Pa+T MC After reaching temperatures below 65℃, warm-up grinding for 10 minutes (adjustable) is performed. Then, the lubrication station and hydraulic station are started, and the grinding rollers are lifted. The roller lifting signal is checked until the +lubricating oil pressure P is reached. RH >0.1MPa + Lubricating oil temperature T RH Once the temperature reaches <45℃, start the mill motor;

[0078] Adjusting the mill inlet regulating valve K MR and circulating air valve K XH Actual value +20% (at this point, all are approximately 40%), adjust the judgment to satisfy -100Pa < P LT <-10Pa+T MC After the temperature drops below 65℃, the mill inlet regulating valve K... MR and circulating air valve K XH The actual value is increased by 20% (at this point, it is approximately 60%), and the valve position is basically in normal production condition. After the valve position is reached, under the adjustment of the automatic pressure stabilization of the flue gas furnace, the flue gas furnace vent valve gradually changes from 100%, 65%, 30%, 0% until it is closed. At this time, the mill outlet temperature T MC Gradually increase, when T MC When the temperature exceeds 65℃, the flue gas furnace heating program is initiated; when T... MC When the temperature is >70℃, the feeder flow range is 30% (flow setpoint L). SD Start the coal feeder belt and cleaning chain, and set the coal feeder flow rate to L. SD After PID control brings the actual flow rate to approximately the set value, and after a 5-second delay, the grinding roller is lowered and pressure is applied to start grinding. The automatic control program for mill outlet temperature and the flue gas furnace pressure stabilization program are then activated. While adjusting the outlet temperature, the automatic control program for mill outlet temperature automatically increases the coal feeder flow rate gradually to near the hourly output (this value can be manually intervened).

[0079] The automatic shutdown sequence is as follows: when the coal powder silo level W... FC When the upper limit is reached, the automatic shutdown program will be initiated after a 40-second delay, and the flue gas furnace will enter the heat preservation program. The mill outlet temperature T MC With flue gas furnace temperature T LT As the temperature decreases, the program enters a 5-second interval for flue gas furnace pressure stabilization and milling temperature limiting control, first collecting the lag T... MC Intermediate temperature variable value T2 at 5-second intervals; when T does not meet the requirements. MC When T < T2-ΔT, but T2-ΔT < T MC Under the condition <T2+ΔT, adjust the mill inlet regulating valve K. MRand circulating air valve K XH Actual value -1% (reduces system airflow to promote temperature drop); when T is not met MC When <T2-ΔT condition, but T is satisfied MC When the condition is greater than T2+ΔT, adjust the feeder flow rate setpoint to increase the feeder flow rate adjustment constant ΔL once, promoting a decrease in TMC until T2+ΔT is reached. MC The condition <T2-ΔT holds true.

[0080] When T is satisfied MC When the condition <T2-ΔT is met, the feeder flow rate setpoint is reduced by the flow rate adjustment constant ΔL once, and then adjusted again after a 5-second interval, until the shutdown safety condition (actual feeder flow rate L) is met. SJ ≤20% of the measuring range + mill outlet temperature T MC <60℃).

[0081] Once the shutdown safety conditions are met, sequentially and fully open the cold air valve K. LF Fully open flue gas furnace vent valve K FS Close the recirculating air valve K XH Close the mill inlet regulating valve K MR The current I of the mill to be ground MJ When the no-load value is near the specified value, lift the grinding roller, stop the grinding mill motor (delay 10 seconds to stop the lubrication station), stop the hydraulic station, stop the main induced draft fan, and wait for the main induced draft fan flow rate L. YFJ <1000NM 3 / h, mill separator shutdown, delay 200S, shutdown bag box backflushing system, shutdown airlock ash discharge valve, shutdown coal powder vibrating screen, close cold air valve, close main exhaust valve, start mill emergency nitrogen charging for 2 minutes and then close, system shutdown completed.

[0082] The interlocking protection logic control unit is activated when a fault occurs in the mill motor, separator, main induced draft fan, sealed coal feeder, or main induced draft fan, triggering the main induced draft fan vibration measurement Z. YFJ Vibration measurement of the input shaft of the mill reducer Z SRZ Mill outlet temperature T MC Outlet temperature T of the bag box BDC Oxygen content at the outlet of the bag box 2 BDC Mill lubricating oil pressure P RH Mill lubricating oil temperature T RH Temperature T of the thrust bearing of the reducer TLW The input shaft temperature T of the reducer SRZ When serious abnormalities occur in the process parameters, the entire pulverizing system can be shut down in a protective manner to prevent further expansion of equipment failure and process safety accidents.

[0083] The system provided in this embodiment employs different adjustment modes for different control parameters based on their varying characteristics. For example, parameters such as gas flow rate and coal feeder flow rate, which can respond quickly, utilize PID control. However, furnace temperature and mill outlet temperature, due to their significant lag and fluctuations within the setpoint range, employ a zonal control approach, approximating the upper and lower edges of a sine wave to reduce adjustment oscillations and avoid overshoot. The automatic combustion control program for the flue gas furnace uses the oxygen content (O2) in the post-combustion flue gas as a reference. 2 LT ), CO content (CO) LT The system automatically adjusts the ratio of combustible gas and combustion air; during system startup, it employs continuous furnace pressure regulation and mill outlet temperature control at different stages of valve position increase and flow rate acceleration; the automatic mill outlet temperature control program uses a hierarchical control mode of coal feed rate regulation (primary regulation), mill inlet valve and circulating air valve position regulation (secondary regulation), and furnace temperature regulation (auxiliary regulation); the start-up and shutdown logic control sequence of the pulverizing system ensures that the pulverized coal preparation system can reliably and safely start up the system equipment one by one and enter normal production; the shutdown procedure ensures that the pulverized coal preparation system can reliably and safely stop the system equipment one by one and enter shutdown state. The interlocking protection program can interlock and protect the shutdown of the entire pulverizing system when key equipment or process parameters experience serious abnormalities.

Claims

1. A fully automatic control system for a pulverized coal preparation device, characterized in that, include: The automatic combustion control unit of the flue gas furnace is configured to enable the flue gas furnace to enter the heat preservation combustion stage in the non-pulverizing state, to enable the flue gas furnace to enter the heat delivery combustion stage in the pulverizing state, to stabilize the furnace temperature at the heat preservation temperature in the heat preservation combustion stage, and to stabilize the furnace temperature at the heat delivery temperature in the heat delivery combustion stage. The furnace pressure stabilization and mill outlet temperature control unit is configured to automatically stabilize the flue gas furnace pressure within the set pressure range and control the mill outlet temperature within a safe range during equipment start-up and shutdown. The mill outlet temperature control unit is configured to automatically adjust the mill outlet temperature when it exceeds the set temperature during production, and to control the equipment to stop if the mill outlet temperature is still higher than the upper temperature limit after adjustment. The start-stop sequence control unit for the pulverizing equipment is configured to call the automatic combustion control unit of the flue gas furnace, the furnace pressure stabilization and mill outlet temperature limiting control unit, and the mill outlet temperature control unit when executing start-stop control, so as to control the equipment to start and stop according to the set start-stop sequence; The mill outlet temperature control unit includes a sealed coal feeder, a mill inlet regulating valve, a circulating air regulating valve, flue gas furnace temperature data, mill differential pressure data, and mill outlet temperature data. Its method for controlling the mill outlet temperature is as follows: When the mill outlet temperature exceeds the set temperature ± deviation value, the coal feed rate will be automatically increased or decreased. If the increase or decrease in the coal feed rate cannot meet the temperature control requirements, the valve positions of the mill inlet regulating valve and the circulating air regulating valve will be adjusted. If the temperature control requirements still cannot be met, the flue gas furnace temperature will be automatically adjusted. If the mill outlet temperature still exceeds the set upper limit after the above adjustments, the equipment will automatically shut down for protection. The specific control method of the mill outlet temperature control unit is as follows: it is adjusted every 10 seconds. When the 10-second pulse is triggered, the mill outlet temperature T is first determined. MC Is it in T? SD -ΔT<T MC <T SD Within the range of +ΔT, where T SD The setpoint for the mill outlet temperature is ΔT, where ΔT is the temperature deviation. If it is within the above range, the setpoint for the coal feeder flow rate is L. SD and the setpoint T for the flue gas furnace heating temperature LTSD2 No adjustments will be made. If the area is not within the above range, adjust as follows: When L is satisfied simultaneously SJ <L SX ΔP MJ <5 kPa, L SJ1 >L SJ3 At that time, the following adjustments will be made: 1.1 If T is satisfied SD +ΔT<T MC For conditions <76℃, the setpoint L for the coal feeder flow rate is... SD An additional feeder flow rate adjustment constant ΔL needs to be added; 1.2) If 76℃ < T MC For conditions <78℃, the setpoint L for the coal feeder flow rate is... SD It is necessary to increase the coal feeder flow rate adjustment constant ΔL by 2 times and activate the air cannon once. 1.3) If T is satisfied MC For conditions >78℃, the setpoint L for the coal feeder flow rate is... SD It is necessary to increase the coal feeder flow rate adjustment constant ΔL by 4 times and activate the air cannon twice at an interval of 10 seconds. 1.4) If T is satisfied MC >78℃ or L SJ >L SX or ΔP MJ >5KPa: The mill inlet regulating valve will be closed by 1% and the circulating air valve will be opened by 1%. If the opening of the mill inlet regulating valve is <50% and the opening of the circulating air valve is >65%, the furnace heating temperature setting will be adjusted once to reduce the mill inlet temperature. 1.5) If T is satisfied MC If the temperature exceeds 85℃, the equipment will initiate an automatic protection shutdown procedure. 2) When T is satisfied simultaneously MC <T SD -ΔT、L SJ1 <L SJ3 At that time, the following adjustments will be made: 2.1) As L SJ >L XX The setpoint L for the coal feeder flow rate SD The feeder flow rate adjustment constant ΔL needs to be reduced once; 2.2) As L SJ <L XX The system will automatically adjust the mill inlet regulating valve by increasing the valve position by 1% and the circulating air valve by decreasing the valve position by 1%. 2.3) If the mill inlet regulating valve is open >65% and the circulating air valve is open <50%, it is determined that the flue gas furnace has a combustion fault, and the alarm will be triggered and the operation will switch to manual mode. The above, L SJ For coal feeder flow rate, L SX For the upper limit of the coal feeder flow rate, ΔP MJ For mill pressure differential value, L XX For the lower limit of coal feeder flow rate, L SJ1 For the instantaneous coal quantity with a 1-second lag, L is a temporary variable. SJ3 This is a temporary variable for the instantaneous coal quantity with a 3-second lag.

2. The fully automatic control system for the pulverized coal preparation equipment according to claim 1, characterized in that, The automatic combustion control unit for the flue gas furnace includes a combustible gas regulating valve, a combustion-supporting fan, furnace temperature data, furnace pressure data, combustion-supporting air flow data, and combustible gas flow data; During the heat preservation and combustion stage, the set values ​​of the combustion air flow and combustible gas flow are automatically replaced with the empirical values ​​of the heat preservation state. During the heat supply and combustion stage, the set values ​​of the combustion air flow and combustible gas flow are automatically replaced with the empirical values ​​of the heat supply. When the furnace temperature exceeds the heat supply temperature, the combustible gas regulating valve and the speed of the combustion air blower are adjusted by PID to stabilize the furnace temperature at the heat supply temperature.

3. The fully automatic control system for the pulverized coal preparation equipment according to claim 2, characterized in that, During the combustion heating stage, the PID control method is as follows: When the furnace temperature is at T LTSD2 -ΔT1<T LT <T LTSD2 When +ΔT1, no adjustment is made; When the furnace temperature is at T LT >T LTSD2 +ΔT1 or T LT <T LTSD2 At -ΔT1, a deviation value ΔF is added or subtracted from the current combustible gas flow rate. The combustion air flow rate changes synchronously with the combustion ratio, achieving a 5-second adjustment cycle. When the temperature rises, the combustion amount is reduced by a deviation value ΔF, and when the temperature falls, the combustion amount is increased by a deviation value ΔF. Where ΔT1 is the temperature adjustment dead zone deviation value, T LTSD2 T is the setpoint for the furnace heating temperature. LT This refers to the furnace temperature.

4. The fully automatic control system for the pulverized coal preparation equipment according to claim 1, characterized in that, The furnace pressure stabilization and mill outlet temperature control unit includes the mill inlet regulating valve, circulating air valve, mill outlet temperature data, and furnace pressure data. The control methods during equipment start-up and shutdown are as follows: When the furnace pressure P LT When P > -10Pa, the circulating air valve is closed by 1%; when P LT <-100Pa or mill outlet temperature T MC When the temperature is above 65℃, the mill inlet regulating valve is closed by 1% to ensure that the flue gas furnace pressure remains stable between -100 and -10Pa during equipment startup or shutdown, thus controlling and limiting the mill outlet temperature to below 65℃.

5. The fully automatic control system for the pulverized coal preparation equipment according to claim 1, characterized in that, The start-up and shutdown sequence control unit of the powder making equipment controls the equipment to start up in the following manner:

1. Determine that all equipment is in a normal startable state, start the bag filter box back-flushing system, delay the start of the pulverized coal vibrating screen, delay the start of the airlock ash discharge valve, open the mill emergency nitrogen charging valve, start the mill separator to run at >40HZ, start the main induced draft fan to run at >15HZ, set the mill inlet regulating valve and circulating air valve to 20%, and start the flue gas furnace pressure stabilization and mill outlet temperature limiting programs; 2. When -100Pa < P LT <-10Pa+T MC After the temperature drops below 65℃, the interlocking protection procedure is activated, where P LT T is the furnace pressure. MC This refers to the mill outlet temperature. The main induced draft fan speeds up to 35Hz, automatically adjusting to meet the condition of -100Pa < P. LT <-10Pa+T MC After the temperature drops below 65℃, the main induced draft fan speed is increased to 45Hz, and then adjusted to ensure that -100Pa < P is met. LT <-10Pa+T MC After reaching a temperature of <65℃, warm up the mill for several minutes under this condition, then start the lubrication station, start the hydraulic station and lift the grinding rollers, and start the mill motor; 4. Adjust the actual opening of the mill inlet regulating valve and the circulating air valve by +20%, and determine if -100Pa < P. LT <-10Pa+T MC After the temperature drops below 65℃, the actual opening value of the mill inlet regulating valve and the circulating air valve is increased by 20%. After the valve position is in place, under the adjustment of the automatic pressure stabilization of the flue gas furnace, the flue gas furnace vent valve gradually changes from 100%, 65%, 30%, 0% until it is closed. 5 when T MC When the temperature exceeds 65℃, the flue gas furnace heating program is initiated; when T... MC When the temperature is above 70℃, start the coal feeder belt and cleaning chain, and set the coal feeder flow rate to L. SD After PID control brings the actual flow rate to approximately the set value, the grinding roller is lowered and pressurized to start grinding after a 5-second delay. The automatic control program for mill outlet temperature and the flue gas furnace pressure stabilization program are then activated. While adjusting the outlet temperature, the automatic control program for mill outlet temperature automatically increases the coal feeder flow rate to near the hourly output.

6. The fully automatic control system for the pulverized coal preparation equipment according to claim 5, characterized in that, The start-up and shutdown sequence control unit of the flour milling equipment controls the equipment to stop in the following manner: When the pulverized coal silo level exceeds the upper limit, the automatic shutdown procedure is initiated after a 40-second delay, and the flue gas furnace enters the heat preservation program. The mill outlet temperature T... MC With flue gas furnace temperature T LT As the temperature decreases, the program enters a 5-second interval for flue gas furnace pressure stabilization and mill outlet temperature limit control. First, collect the hysteresis T. MC Temperature sampling value T2 at 5-second intervals; when T does not meet the requirements. MC <T2-ΔT but satisfies T2-ΔT<T MC <T2+ΔT condition, where ΔT is the temperature deviation value, adjust the opening of the mill inlet regulating valve and the circulating air valve to decrease by 1%; when T is not satisfied MC <T2-ΔT condition but satisfy T MC When the condition is greater than T2+ΔT, adjusting the feeder flow rate setpoint increases the feeder flow rate adjustment constant ΔL, thus promoting T. MC Decrease until T MC The condition <T2-ΔT holds true; When T is satisfied MC When the condition <T2-ΔT is met, the feeder flow rate setpoint is reduced by the flow rate adjustment constant ΔL once, and then adjusted again after a 5-second interval, until the shutdown safety condition (feeder flow rate L) is met. SJ ≤20% of the measuring range + mill outlet temperature T MC <60℃; After the shutdown safety conditions are met, sequentially fully open the cold air valve, fully open the flue gas furnace vent valve, close the circulating air valve, close the mill inlet regulating valve, and when the mill current reaches near the no-load value, raise the grinding rollers, stop the mill motor, stop the hydraulic station, and stop the main induced draft fan. Wait until the main induced draft fan flow rate is <1000 Nm³. 3 / h, the mill separator stops, after a 200-second delay, the bag filter backflushing system stops, the airlock ash discharge valve stops, the coal powder vibrating screen stops, the cold air valve closes, the main exhaust valve closes, the mill emergency nitrogen charging starts and closes after 2 minutes, and the system shutdown is complete.

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