Full-automatic control system of pulverized coal preparation equipment

Abstract

The invention provides a full-automatic control system of pulverized coal preparation equipment. The full-automatic control system comprises a flue gas furnace automatic combustion control unit, a hearth pressure stabilizing and mill outlet temperature limiting control unit, a mill outlet temperature control unit and a powder preparation equipment start-stop sequence control unit. The system is a full-automatic control system capable of realizing automatic start-stop and production of the whole system and automatically adjusting the temperature of the outlet of the mill and the pressure of the hearth of the flue gas furnace, and can realize full-automatic control of a pulverized coal preparation process, so that the workload of post operators can be greatly reduced, and the safe operation level of process production is improved.

Description

Technical Field

[0001] The present invention mainly relates to the technical field related to coal powder preparation, and in particular to a fully automatic control system for coal powder preparation equipment. Background Art

[0002] Pulverized coal injection (PFI) in blast furnaces (BFs) is an important means of conserving coke, reducing ironmaking costs, and mitigating environmental pollution. Pulverized coal preparation is a key production process for BF PFI. Currently, the main equipment for PFI production includes a raw coal yard, raw coal bunker, flue gas furnace, mill, baghouse, and pulverized coal bunker. The raw coal yard feeds the raw coal bunker via a belt conveyor and iron remover. The bunker is equipped with an air cannon, and the flue gas furnace is controlled by a variable-frequency combustion-supporting blower and corresponding valves. Currently, PFI primarily relies on computer-based parameter monitoring and keyboard-based manual remote control. System startup and shutdown, as well as production, require operators to follow operating procedures and perform step-by-step operations based on actual display parameters. This requires significant workload and a high level of responsibility. Incorrect operation can lead to faults or safety issues such as flue gas furnace flameout, excessive mill outlet temperature, and internal mill explosions. Therefore, fully automated PFI production has long been a pressing need for personnel working in the PFI process. Summary of the Invention

[0003] In order to address the deficiencies of current technology, the present invention combines existing technology with practical application to provide a fully automatic control system for coal powder preparation equipment. The present invention is a fully automatic control system that can realize automatic start and stop, production, and automatic adjustment of the mill outlet temperature and flue gas furnace pressure of the entire system. It can realize fully automatic control of the coal powder preparation process, thereby greatly reducing the workload of job operators and improving the safe operation level of process production.

[0004] The technical solutions of the present invention are as follows:

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

[0006] The furnace pressure stabilization and mill outlet temperature limiting 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 value range during the equipment start-up and shutdown process;

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

[0008] The start-stop sequence control unit of the pulverizing equipment is configured to call the flue gas furnace automatic combustion control unit, the furnace pressure stabilization and mill outlet temperature limit control unit, and the mill outlet temperature control unit when executing start-stop control, and control the equipment to start and stop according to the set start-up and shutdown 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 combustion stage, the set values of the combustion air flow and the combustible gas flow are automatically replaced with the experience values of the heat preservation state. During the heat delivery combustion stage, the set values of the combustion air flow and the combustible gas flow are automatically replaced with the experience values of the heat delivery state. When the furnace temperature exceeds the heat delivery temperature, the combustible gas regulating valve and the combustion fan speed are adjusted by PID to stabilize the furnace temperature at the heat delivery temperature.

[0011] Furthermore, in the temperature delivery combustion stage, the PID adjustment method is as follows:

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

[0013] When the furnace temperature is T LT >T LTSD2 +ΔT1 or T LT <T LTSD2 -ΔT1, a deviation value ΔF is reduced or increased based on the current combustible gas flow value, and the combustion-supporting air flow value changes synchronously according to the combustion ratio, so that 5S is an adjustment period. When the temperature rises, the combustion amount is reduced by the deviation value ΔF, and when the temperature drops, the combustion amount is increased by the deviation value ΔF;

[0014] Among them, ΔT1 is the temperature adjustment dead zone deviation value, T LTSD2 is the furnace heating temperature setting value, T LT is the furnace temperature.

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

[0016] When the furnace pressure P LT >-10Pa, the circulating air valve is closed 1%; when P LT <-100Pa or mill outlet temperature T MCWhen the temperature is greater than 65℃, the regulating valve at the mill inlet is closed by 1% so that the pressure in the flue gas furnace is always stable between -100 and -10Pa during the start-up or shutdown of the equipment, and the mill outlet temperature is controlled to be less than 65℃.

[0017] Furthermore, the mill outlet temperature control unit includes a closed coal feeder, a mill inlet regulating valve, a circulating air regulating valve, flue gas furnace temperature data, mill pressure difference data, and mill outlet temperature data. The mill outlet temperature control method is:

[0018] When the mill outlet temperature exceeds the set temperature ± the deviation value, the coal feed will be automatically increased or decreased; when the increase or decrease in the coal feed 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 are still not met, the flue gas furnace temperature will be automatically adjusted; if the mill outlet temperature still exceeds the set upper limit after the above adjustment, the equipment will automatically shut down for protection.

[0019] Furthermore, the specific control mode of the mill outlet temperature control unit is as follows: it is adjusted every 10 seconds. When the 10S pulse is triggered, the mill outlet temperature T is first determined. MC Is it in T SD -ΔT<T MC <T SD +ΔT range, where T SD is the mill outlet temperature setting value, ΔT is the temperature deviation value, if it is within the above range, the coal feeder flow setting value L SD And the flue gas furnace furnace temperature setting value T LTSD2 No adjustment will be made. If it is not within the above range, the following adjustments will be made:

[0020] 2) When L SJ <L SX , ΔP MJ <5KPa、L SJ1 >L SJ3 , make the following adjustments:

[0021] 1.1 If T is satisfied SD +ΔT<T MC <76℃, the coal feeder flow setting value L SD It is necessary to increase the flow adjustment constant ΔL of the coal feeder once;

[0022] 1.2) If 76℃<T MC <78℃, the coal feeder flow setting value L SD It is necessary to increase the coal feeder flow adjustment constant ΔL by 2 times and open the air cannon once more;

[0023] 1.3) If T is satisfied MC>78℃, the coal feeder flow setting value is L SD It is necessary to increase the coal feeder flow adjustment constant ΔL by 4 times and open the air cannon twice with an additional 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 automatically adjusted to close by 1% and the circulating air valve will be increased by 1%. If the mill inlet regulating valve opening is less than 50% and the circulating air valve opening is greater than 65%, the furnace temperature setting will be adjusted once to reduce the mill inlet temperature.

[0025] 1.5) If T is satisfied MC >85℃, the equipment starts the automatic protection shutdown program;

[0026] 2 When T is satisfied at the same time MC <T SD -ΔT, L SJ1 <L SJ3 , make the following adjustments:

[0027] 2.1 Such as L SJ >L XX , then the coal feeder flow setting value L SD The flow adjustment constant ΔL of the primary coal feeder needs to be reduced;

[0028] 2.2 Such as L SJ <L XX , the mill inlet regulating valve will be automatically adjusted to increase the valve position by 1% and the circulating air valve will be automatically adjusted to decrease the valve position by 1%.

[0029] 2.3 If the opening of the mill inlet regulating valve is greater than 65% and the opening of the circulating air valve is less than 50%, it is judged that the flue gas furnace has a burning fault and the alarm is turned to manual operation;

[0030] Above, L SJ is the coal feeder flow rate, L SX is the upper limit of coal feeder flow rate, ΔP MJ is the mill pressure difference value, L XX is the lower limit of coal feeder flow, L SJ1 is the instantaneous coal quantity temporary variable with a 1s lag, L SJ3 It is a temporary variable of instantaneous coal quantity with a lag of 3s.

[0031] Furthermore, the start-stop sequence control unit of the milling equipment controls the equipment to start as follows:

[0032] 1. Determine that all equipment is in a normal start-up state, start the bag box backflush system, delay the start of the pulverized coal screen, delay the start of the air lock ash discharge valve, open the mill emergency nitrogen filling valve, start the mill separator to run to >40HZ, start the main induced draft fan to run to >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 limit program;

[0033] 2 When -100Pa<P LT <-10Pa+T MC When the temperature is below 65℃, the chain protection program is activated. LT is the furnace pressure, T MC is the mill outlet temperature;

[0034] 3. The main induced draft fan speed increases to 35HZ and automatically adjusts to meet -100Pa<P LT <-10Pa+T MC <65℃, the main induced draft fan speed is increased to 45HZ, and then adjusted to meet the -100Pa <P LT <-10Pa+T MC After the temperature is less than 65℃, warm the mill for several minutes under this condition, start the lubrication station, start the hydraulic station, lift the grinding roller, and start the mill motor;

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

[0036] 5 When T MC >65℃, start the flue gas furnace temperature sending program; when T MC When the temperature is higher than 70℃, start the coal feeder belt and cleaning chain, and set the coal feeder flow rate to L SD Through PID control, the actual flow rate reaches the approximate set value. After a delay of 5S, the grinding roller is dropped and pressure is applied to start pulverizing. The automatic control program of the mill outlet temperature and the flue gas furnace pressure stabilization program are put into operation. While adjusting the outlet temperature, the automatic control program of the mill outlet temperature automatically increases the coal feeder flow rate to near the hourly output.

[0037] Furthermore, the start-stop sequence control unit of the milling equipment controls the equipment to shut down as follows:

[0038] When the pulverized coal bin level is greater than the upper limit, the system will automatically shut down after a delay of 40 seconds, and the flue gas furnace will enter the insulation program. The mill outlet temperature T MC Furnace temperature of flue gas furnace TLT The program enters the 5S interval flue gas furnace voltage stabilization and mill outlet temperature limit control;

[0039] First, collect the hysteresis T MC T2 temperature sampling value at intervals of 5S; when T MC <T2-ΔT condition but satisfies T2-ΔT<T MC <T2+ΔT condition, ΔT is the temperature deviation value, adjust the mill inlet regulating valve and circulating air valve opening to reduce by 1%; when T is not met MC <T2-ΔT condition but satisfies T MC >T2+ΔT, adjust the coal feeder flow setting value to increase the coal feeder flow adjustment constant ΔL to promote T MC Decrease until T MC <T2-ΔT condition holds true;

[0040] When T is satisfied MC When the condition is less than T2-ΔT, the coal feeder flow setting value is reduced by the flow adjustment constant ΔL, and then adjusted again after 5S interval until the shutdown safety condition is reached (coal feeder flow L SJ ≤20% of the measuring range + mill outlet temperature T MC <60℃;

[0041] When the shutdown safety conditions are met, open the cold air valve, open the flue gas furnace vent valve, close the circulating air valve, close the mill inlet regulating valve, wait for the mill current to reach the no-load value, lift the grinding roller, stop the mill motor, stop the hydraulic station, stop the main induced draft fan, and wait for the main induced draft fan flow to be less than 1000NM 3 / h, the mill separator is shut down, the bag box backflush system is shut down with a delay of 200S, the air lock ash unloading valve is shut down, the coal powder vibrating screen is shut down, the cold air valve is closed, the main exhaust valve is closed, the mill emergency nitrogen filling is turned on and closed after 2 minutes, and the system shutdown is completed.

[0042] Beneficial effects of the present invention:

[0043] 1. The control system of the present invention can utilize the existing PLC control system, with the help of relevant equipment and detection parameters in the coal powder preparation process, through years of accumulated production operation experience and exploration and practice of production process control, to compile a process control flow of automatic combustion of the flue gas furnace, automatic adjustment of the mill outlet temperature, one-button sequential start and stop of the pulverizing system, valve position segmented control of furnace pressure stabilization and mill outlet temperature limit during start and stop, and segmented control of flue gas flow rate. By compiling calculation and control programs that conform to the actual process, fully automatic control of the coal powder preparation process can be achieved, thereby greatly reducing the workload of post operators and improving the safe operation level of process production.

[0044] 2. The control system of the present invention adopts different adjustment modes for different control parameters according to their different characteristics. For example, PID adjustment is adopted for the gas flow rate and coal feeder flow rate, which are parameters that can respond quickly. However, due to the large hysteresis and fluctuation pattern of the furnace temperature and mill outlet temperature within the upper and lower ranges of the set values, the control concept of approximating the upper and lower edges of the positive and negative zones of the sine wave is adopted to reduce the oscillation amplitude of the adjustment and avoid overshoot.

[0045] 3. The control system of the present invention automatically adjusts the ratio of combustible gas and combustion-supporting air in the flue gas furnace automatic combustion control unit according to the oxygen content and CO content in the flue gas after combustion; during the system startup process, continuous furnace pressure stabilization adjustment and mill outlet temperature limit control are adopted in different stages of valve position segmentation increase and flow segmentation speed increase; the mill outlet temperature automatic control program adopts coal feed amount adjustment (main adjustment), mill inlet valve and circulation air valve valve position adjustment (secondary adjustment, furnace temperature adjustment (auxiliary) hierarchical control mode; the start-stop logic control sequence of the pulverizing system can ensure that the pulverized coal preparation system can reliably and safely start the system equipment one by one and enter the normal production state; the stop 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, and the interlocking protection program can shut down the entire pulverizing system for interlocking protection when serious abnormalities occur in key equipment or process parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Attachment Figure 1 This is the control principle diagram of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present application.

[0048] This embodiment provides a fully automatic control system for coal powder preparation equipment. Utilizing a PLC control system, based on process equipment configuration and process control principles, the system develops segmented and functional functions 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, and start-up and shutdown sequence and interlocking protection of the pulverizing system. The system also organically combines the above four control units to achieve fully automatic control of the coal powder preparation process, replacing current manual operations and improving the operational level, safety, and reliability of the coal powder preparation process.

[0049] The control system of the present invention mainly includes a flue gas furnace automatic combustion control unit, a furnace pressure stabilization and mill outlet temperature limit control unit, a mill outlet temperature control unit, a pulverizing equipment start-stop sequence control unit, and an interlocking protection logic control unit. The flue gas furnace automatic combustion control unit realizes automatic operation of the two process states of insulation and heat delivery; the furnace pressure stabilization and mill outlet temperature limit control unit ensures that the flue gas furnace combustion is stable and the mill outlet temperature does not exceed the limit during the production start-stop process; the mill outlet temperature control unit can realize the automatic increase and decrease of coal quantity, valve fine-tuning and flue gas furnace temperature fine-tuning functions during the production process; the pulverizing equipment start-stop sequence control unit realizes safe and reliable start-stop automatic operation of the entire production process under the premise of calling the above units; the interlocking protection logic control unit ensures that the system can be safely stopped when the process equipment fails and the process parameters are extremely abnormal. The above control units are described in detail below.

[0050] Flue gas furnace automatic combustion control unit:

[0051] The common states of a flue gas furnace during the pulverized coal preparation process 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 flue gas furnace automatic combustion control unit in this embodiment primarily includes a variable-frequency combustion-supporting blower, a combustible gas pipeline regulating valve and shut-off valve, a chimney vent valve, and equipment for measuring furnace temperature, pressure, oxygen and CO content, combustible gas flow rate, pressure, and temperature. The software primarily consists of two programs: heat preservation combustion and heat supply combustion.

[0052] Among them, when the heat preservation combustion is in the non-pulverizing working state, the system program automatically replaces the set values of the combustion-supporting air flow rate and the combustible gas flow rate with the heat preservation state experience value (preliminary debugging experimental value), so that the furnace temperature is basically stable at 400-450℃, and the fixed air conditioning combustible gas combustion control based on the flue gas content value is assisted to keep the flame from being extinguished with the lowest combustible gas consumption.

[0053] When the temperature-supply combustion is in the pulverizing working state and the system program enters the temperature-supply combustion, the set values of the combustion-supporting air flow rate and the combustible gas flow rate are automatically replaced with the temperature-supply experience values (preliminary debugging experimental values), so that the furnace temperature gradually approaches about 950℃, and the fixed air conditioning combustible gas combustion control based on the flue gas content value is assisted. When the furnace temperature exceeds the range of 950±10℃, the combustible gas regulating valve and the combustion-supporting fan speed are automatically adjusted, thereby adjusting the optimal flow ratio of the combustible gas and the combustion-supporting air, so that the furnace temperature is stabilized within the range of 950±10℃.

[0054] The process equipment and control parameters of this control program are determined by the combustible gas regulating valve K KR , cut-off valve K QD , combustion-supporting fan S ZR , Chimney relief valve K FS , flame detection HY1 , furnace temperature T LT Furnace pressure P LT , furnace oxygen content O 2 LT 、Furnace CO content CO LT This control unit can operate in two states: heat preservation and heat delivery according to production conditions.

[0055] During heat preservation operation, it is only necessary to adjust the flow rate to the low empirical value commonly used, and adjust the optimal combustion ratio by detecting the combustion gas content to ensure low flow rate economic combustion. When delivering heat, the furnace temperature and combustion conditions need to be adjusted: set T according to the furnace temperature LTSD2 The value is automatically adjusted to the commonly used air-fuel flow value and the experience debugging value, which assists the combustion gas content O 2 LT 、CO LT Detection and adjustment of the combustible gas regulating valve K through PID KR Opening and combustion fan S ZR The rotation speed makes the furnace burn at the optimal combustion ratio;

[0056] When the furnace temperature is T LTSD2 -ΔT1<T LT <T LTSD2 +ΔT1, when ΔT1 is the dead zone value, no adjustment is made; when the furnace temperature is T LT >T LTSD2 +ΔT1 or T LT <T LTSD2 -ΔT1, respectively at the current combustible gas flow value F KES Based on the above, a deviation value ΔF is reduced or increased, and the combustion air flow value F ZRS According to the synchronous change of the combustion ratio, the adjustable period of 5S can be achieved. When the temperature rises, the combustion amount is reduced by ΔF, and when the temperature drops, the combustion amount is increased by ΔF, which is automatically controlled to stabilize the furnace temperature within the deviation range of the set value.

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

[0058] During system startup and shutdown and normal production, the flue gas furnace pressure can automatically stabilize within the range of -100 to -10Pa, which can avoid the occurrence of flue gas furnace flameout and smoking; the mill outlet temperature is controlled within the safe value, which can effectively avoid the occurrence of system explosion safety accidents.

[0059] The process equipment and control parameters of this control unit are controlled by the mill inlet regulating valve K MR , Circulation air valve K XH , mill outlet temperature T MC , furnace pressure PLT During the system startup and shutdown process, when P LT >-10Pa, circulation air valve K XH Close the valve position by 1%; when P LT <-100Pa or T MC >65℃, the mill inlet regulating valve K MR Close the valve position by 1%. Its function is to ensure that the flue gas furnace pressure P LT Always keep it stable between -100~-10 Paz to prevent the occurrence of dangerous phenomena such as flameout or flameout of the flue gas furnace; limit the mill outlet temperature (T MC )<65℃, which is a safety requirement to ensure the system start and stop process.

[0060] Mill outlet temperature control unit:

[0061] The system primarily consists of three functions: coal feed rate regulation (primary), mill inlet valve and circulating air valve position adjustment (secondary), and furnace temperature regulation (auxiliary). When the mill outlet temperature exceeds the set temperature ± a deviation value, the coal feed rate is automatically increased or decreased. If the increase or decrease in coal feed rate fails to meet temperature control requirements, the position of the mill inlet regulating valve and circulating air regulating valve are adjusted. If this still fails to meet temperature control requirements, 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 these adjustments, a system abnormality has occurred 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 , Circulation air valve K XH , Coal feeder flow setting value L SD , mill outlet temperature T MC , mill outlet temperature setting value T SD , temperature deviation value ΔT, coal feeder flow setting value L SD , Coal feeder flow measurement value L SJ , Coal feeder flow upper limit L SX , Coal feeder flow lower limit L XX , coal feeder flow adjustment constant ΔL, mill pressure difference ΔP MJ This solution is adjusted once every 10 seconds. When the 10S pulse is triggered, the current temperature T is first determined. MC Is the value in this T SD- ΔT<T MC <T SD +ΔT range? If within the above range, the coal feeder flow setting value L SD And the flue gas furnace temperature setting value T LTSD2 No adjustment will be made. If it is not within the above range:

[0063] When the coal feeder flow rate L SJ <Coal feeder flow upper limit L SX + mill pressure difference ΔPMJ<5KPa and instantaneous coal quantity temporary variable L SJ1 > Instantaneous coal quantity temporary variable L SJ3 When (the parameter is running on the rising edge of the positive area of the control curve), the program enters the following adjustments:

[0064] 1.1) If T is satisfied SD +ΔT<T MC If the temperature is less than 76℃, the coal feeder flow setting value needs to increase the coal feeder flow adjustment constant ΔL once;

[0065] 1.2) If 76℃<T MC If the temperature is less than 78℃, the coal feeder flow setting value needs to be increased by 2 times the coal feeder flow adjustment constant ΔL, and an additional air cannon should be opened.

[0066] 1.3) If T is satisfied MC If the temperature is higher than 78℃, the coal feeder flow rate setting value needs to be increased by 4 times the coal feeder flow rate adjustment constant ΔL, and the air cannon should be opened twice with an additional interval of 10S;

[0067] 1.4) If T is satisfied MC >78℃ or coal feeder flow rate L SJ > Coal feeder flow upper limit L SX Or mill pressure difference ΔP MJ Greater than 5KPa: automatically adjust the opening of the mill inlet regulating valve to K MR -1%, the opening of the circulating air valve is K XH +1%; if the valve opening is at K MR <50%、K XH >65%, then adjust the flue gas furnace temperature setting value to T LTSD2 -100℃ to reduce the mill inlet temperature;

[0068] 1.5) If T is satisfied MC >85℃, the system starts the automatic protection shutdown program.

[0069] 2) When T MC <T SD -ΔT and instantaneous coal quantity temporary variable L SJ1 <Instantaneous coal quantity temporary variable L SJ3 When (the parameter is running on the falling edge of the negative area of the control curve), the program enters the following adjustments:

[0070] 2.1) For example, the coal feeder flow rate L SJ >Coal feeder flow lower limit L XX, then the coal feeder flow setting value needs to be reduced by one coal feeder flow adjustment constant ΔL;

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

[0072] 2.3) If the valve opening is at K MR >65%、K XH If the value is less than 50%, it is judged that the flue gas furnace has a burning failure and the alarm is turned to manual operation.

[0073] Pulverizing equipment start and stop sequence control unit:

[0074] The startup sequence program 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 stop 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.

[0075] The aforementioned control unit is called upon to participate in the control during the start-up and shutdown periods. After startup, the process is mainly maintained in a stable production manner by the automatic control unit for the mill outlet temperature and the automatic combustion control unit for the flue gas furnace.

[0076] Among them, in this control unit, the automatic start sequence is: determine that the flue gas furnace is in normal insulation state + the raw coal bin level W YM Higher than the low material level (if lower than the low material level, the loading program will automatically run) + coal powder bin 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 the conditions are met, start the bag box backflush system, delay the start of the pulverized coal screen, delay the start of the air lock ash discharge valve, open the mill emergency nitrogen filling valve (stop after 3 minutes), start the mill separator to run to >40HZ, start the main induced draft fan to run to >15HZ, and adjust the mill inlet K MR and circulating air K XH All are set to 20%, start the flue gas furnace voltage stabilization and grinding temperature limit program;

[0077] When -100Pa<P LT <-10Pa+T MC When the temperature is less than 65℃, the system enters the interlock protection program; the main induced draft fan speed increases to 35HZ and automatically adjusts to meet -100Pa<P LT<-10Pa+T MC <65℃, the main induced draft fan speed is increased to 45HZ, and then adjusted to meet the -100Pa <P LT <-10Pa+T MC After the temperature is less than 65℃, warm the grinding wheel for 10 minutes (adjustable), start the lubrication station, start the hydraulic station and lift the grinding roller, and judge whether the grinding roller lifting signal reaches + lubricating oil pressure P RH >0.1MPa+lubricating oil temperature T RH When the temperature is less than 45℃, start the mill motor;

[0078] Adjust the mill inlet regulating valve K MR And circulating air valve K XH Actual value + 20% (about 40% at this time), adjust the judgment to meet -100Pa<P LT <-10Pa+T MC After the temperature is less than 65℃, the mill inlet regulating valve K MR And circulating air valve K XH The actual value is +20% (about 60% at this time), and the valve position is basically in normal production state; after the valve position is in place, under the adjustment of the automatic voltage stabilization of the flue gas furnace, the flue gas furnace vent valve gradually increases from 100%, 65%, 30%, 0% until it is closed. At this time, the mill outlet temperature T MC Gradually increase, when T MC >65℃, start the flue gas furnace temperature sending program; when T MC >70℃, 30% of coal feeder flow range (flow setting value L SD ) Start the coal feeder belt and cleaning chain, and set the coal feeder flow rate to L SD Through PID control, the actual flow rate reaches the approximate set value. After a delay of 5S, the grinding roller is dropped and pressure is applied to start pulverizing. The automatic control program of the mill outlet temperature and the flue gas furnace pressure stabilization program are put into operation. While adjusting the outlet temperature, the automatic control program of the mill outlet temperature automatically increases the coal feeder flow rate to near the hourly output (this value can be manually intervened).

[0079] The automatic shutdown sequence is: when the coal powder bin level W FC > When the upper limit is reached, the system will enter the automatic shutdown program after a delay of 40 seconds, and the flue gas furnace will enter the insulation program. The mill outlet temperature T MC Furnace temperature of flue gas furnace T LT The program enters the 5S interval flue gas furnace voltage stabilization and grinding temperature limit control, first collects the hysteresis T MC The intermediate variable value of T2 temperature at intervals of 5S; when T MC <T2-ΔT condition, but satisfying T2-ΔT<T MC <T2+ΔT condition, adjust the mill inlet regulating valve K MRAnd circulating air valve K XH Actual value -1% (reducing system air volume to promote temperature drop); when T is not met MC <T2-ΔT condition, but satisfies T MC >T2+ΔT, adjust the coal feeder flow setting value to increase the coal feeder flow adjustment constant ΔL once, to promote the decrease of TMC until T MC The condition of <T2-ΔT is met.

[0080] When T is satisfied MC When the condition is less than T2-ΔT, the coal feeder flow setting value is reduced by the flow adjustment constant ΔL, and then adjusted again after 5S interval until the shutdown safety condition is reached (the actual value of the coal feeder flow L SJ ≤20% of the measuring range + mill outlet temperature T MC <60℃).

[0081] When the shutdown safety conditions are met, open the cold air valve K in sequence LF , Fully open the flue gas furnace vent valve K FS , Close the circulating air valve K XH , Close the mill inlet regulating valve K MR , waiting mill current I MJ When the no-load value is close to the value, lift the grinding roller, stop the grinding motor (delay 10S 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, shut down the mill separator, delay 200S, shut down the bag box backflush system, shut down the air lock ash unloading valve, shut down the coal powder vibrating screen, close the cold air valve, close the main exhaust valve, open the mill emergency nitrogen filling for 2 minutes and then close it, and the system shutdown is completed.

[0082] The interlocking protection logic control unit is in the event of a fault in the mill motor, separator, main induced draft fan, closed coal feeder, or main induced draft fan. YFJ , Grinding mill reducer input shaft vibration measurement Z SRZ , mill outlet temperature T MC , bag box outlet temperature T BDC , oxygen content at bag box outlet O 2 BDC , mill lubricating oil pressure P RH , mill lubricating oil temperature T RH , reducer thrust bearing temperature T TLW , reducer input shaft temperature T SRZ When serious abnormalities occur in process parameters, the entire milling system can be shut down for protection, avoiding further expansion of equipment failure scope and process production safety accidents.

[0083] The system provided in this embodiment adopts different adjustment modes for different control parameters according to their different characteristics. For example, the gas flow and coal feeder flow are parameters that can respond quickly and are PID regulated. However, the furnace temperature and mill outlet temperature, due to their large hysteresis and fluctuation pattern within the range of the set value, adopt the control idea of the upper and lower edges of the positive and negative zones of the approximate sine wave to reduce the oscillation amplitude of the regulation and avoid overshoot. In the automatic combustion control program of the flue gas furnace, the oxygen content (O) in the flue gas after combustion is used as the control parameter. 2 LT ), CO content (CO LT ) Automatically adjust the ratio of combustible gas and combustion-supporting air; during the system startup process, continuous furnace pressure stabilization and mill outlet temperature limit control are adopted in different stages of valve position segmentation increase and flow segmentation speed increase; the mill outlet temperature automatic control program adopts coal feed adjustment (main adjustment), mill inlet valve and circulating air valve valve position adjustment (secondary adjustment), furnace temperature adjustment (auxiliary) hierarchical control mode; the start and stop logic control sequence of the pulverizing system can ensure that the pulverized coal preparation system can reliably and safely start the system equipment one by one and enter normal production status; the stop 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 interlocking protection program can shut down the entire pulverizing system for interlocking protection when serious abnormalities occur in key equipment or process parameters.

Claims

1. A fully automatic control system for coal powder preparation equipment, characterized in that: include: The automatic combustion control unit of the flue gas furnace is configured to make the flue gas furnace enter the heat preservation combustion stage in the non-pulverizing state, and to make the flue gas furnace 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 limiting 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 value range during the equipment start-up and shutdown process; The mill outlet temperature control unit is configured to automatically adjust the mill outlet temperature when the mill outlet temperature exceeds the set temperature during the production process, and control the equipment to shut down if the mill outlet temperature is still higher than the temperature upper limit after adjustment; The start-stop sequence control unit of the pulverizing equipment is configured to call the flue gas furnace automatic combustion control unit, the furnace pressure stabilization and mill outlet temperature limit control unit, and the mill outlet temperature control unit when executing start-stop control, and control the equipment to start and stop according to the set start-up and shutdown sequence.

2. The fully automatic control system for pulverized coal preparation equipment according to claim 1, characterized in that: 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; During the heat preservation combustion stage, the set values of the combustion air flow and the combustible gas flow are automatically replaced with the experience values of the heat preservation state. During the heat delivery combustion stage, the set values of the combustion air flow and the combustible gas flow are automatically replaced with the experience values of the heat delivery state. When the furnace temperature exceeds the heat delivery temperature, the combustible gas regulating valve and the combustion fan speed are adjusted by PID to stabilize the furnace temperature at the heat delivery temperature.

3. The fully automatic control system for coal powder preparation equipment according to claim 2, characterized in that: In the temperature delivery combustion stage, the PID adjustment method is as follows: When the furnace temperature is T LTSD2 -ΔT1<T LT <T LTSD2 When +ΔT1, no adjustment is made; When the furnace temperature is T LT >T LTSD2 +ΔT1 or T LT <T LTSD2 -ΔT1, a deviation value ΔF is reduced or increased based on the current combustible gas flow value, and the combustion-supporting air flow value changes synchronously according to the combustion ratio, so that 5S is an adjustment period. When the temperature rises, the combustion amount is reduced by the deviation value ΔF, and when the temperature drops, the combustion amount is increased by the deviation value ΔF; Among them, ΔT1 is the temperature adjustment dead zone deviation value, T LTSD2 is the furnace heating temperature setting value, T LT is the furnace temperature.

4. The fully automatic control system for pulverized coal preparation equipment according to claim 1, characterized in that: The furnace pressure stabilization and mill outlet temperature limit control unit includes the mill inlet regulating valve, circulating air valve, mill outlet temperature data, and furnace pressure data. The control method during the equipment start-up and shutdown process is as follows: When the furnace pressure P LT >-10Pa, the circulating air valve is closed 1%; when P LT <-100Pa or mill outlet temperature T MC When the temperature is greater than 65℃, the regulating valve at the mill inlet is closed by 1% so that the pressure in the flue gas furnace is always stable between -100 and -10Pa during the start-up or shutdown of the equipment, and the mill outlet temperature is controlled to be less than 65℃.

5. The fully automatic control system for pulverized coal preparation equipment according to claim 1, characterized in that: The mill outlet temperature control unit includes a closed coal feeder, a mill inlet regulating valve, a circulating air regulating valve, flue gas furnace temperature data, mill pressure difference data, and mill outlet temperature data. The mill outlet temperature control method is as follows: When the mill outlet temperature exceeds the set temperature ± the deviation value, the coal feed will be automatically increased or decreased; when the increase or decrease in the coal feed 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 are still not met, the flue gas furnace temperature will be automatically adjusted; if the mill outlet temperature still exceeds the set upper limit after the above adjustment, the equipment will automatically shut down for protection.

6. The fully automatic control system for pulverized coal preparation equipment according to claim 5, characterized in that: The specific control method of the mill outlet temperature control unit is as follows: adjust once every 10 seconds. When the 10S pulse is triggered, first determine the mill outlet temperature T MC Is it in T SD -ΔT<T MC <T SD +ΔT range, where T SD is the mill outlet temperature setting value, ΔT is the temperature deviation value, if it is within the above range, the coal feeder flow setting value L SD And the flue gas furnace furnace temperature setting value T LTSD2 No adjustment will be made. If it is not within the above range, the following adjustments will be made: 1) When L SJ <L SX , ΔP MJ <5KPa、L SJ1 >L SJ3 , make the following adjustments: 1.1 If T is satisfied SD +ΔT<T MC <76℃, the coal feeder flow setting value L SD It is necessary to increase the flow adjustment constant ΔL of the coal feeder once; 1.2) If 76℃<T MC <78℃, the coal feeder flow setting value L SD It is necessary to increase the coal feeder flow adjustment constant ΔL by 2 times and open the air cannon once more; 1.3) If T is satisfied MC >78℃, the coal feeder flow setting value is L SD It is necessary to increase the coal feeder flow adjustment constant ΔL by 4 times and open the air cannon twice with an additional 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 automatically adjusted to close by 1% and the circulating air valve will be increased by 1%. If the mill inlet regulating valve opening is less than 50% and the circulating air valve opening is greater than 65%, the furnace temperature setting will be adjusted once to reduce the mill inlet temperature. 1.5) If T is satisfied MC >85℃, the equipment starts the automatic protection shutdown program; 2 When T is satisfied at the same time MC <T SD -ΔT, L SJ1 <L SJ3 , make the following adjustments: 2.1 Such as L SJ >L XX , then the coal feeder flow setting value L SD The flow adjustment constant ΔL of the primary coal feeder needs to be reduced; 2.2 Such as L SJ <L XX , the mill inlet regulating valve will be automatically adjusted to increase the valve position by 1% and the circulating air valve will be automatically adjusted to decrease the valve position by 1%. 2.3 If the opening of the mill inlet regulating valve is greater than 65% and the opening of the circulating air valve is less than 50%, it is judged that the flue gas furnace has a burning fault and the alarm is turned to manual operation; Above, L SJ is the coal feeder flow rate, L SX is the upper limit of coal feeder flow rate, ΔP MJ is the mill pressure difference value, L XX is the lower limit of coal feeder flow, L SJ1 is the instantaneous coal quantity temporary variable with a 1s lag, L SJ3 It is a temporary variable of instantaneous coal quantity with a lag of 3s.

7. The fully automatic control system for pulverized coal preparation equipment according to claim 1, characterized in that: The start-stop sequence control unit of the milling equipment controls the equipment to start as follows:

1. Determine that all equipment is in a normal start-up state, start the bag box backflush system, delay the start of the pulverized coal screen, delay the start of the air lock ash discharge valve, open the mill emergency nitrogen filling valve, start the mill separator to run to >40HZ, start the main induced draft fan to run to >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 limit program; 2 When -100Pa<P LT <-10Pa+T MC When the temperature is below 65℃, the chain protection program is activated. LT is the furnace pressure, T MC is the mill outlet temperature; 3. The main induced draft fan speed increases to 35HZ and automatically adjusts to meet -100Pa<P LT <-10Pa+T MC <65℃, the main induced draft fan speed is increased to 45HZ, and then adjusted to meet the -100Pa <P LT <-10Pa+T MC After the temperature is less than 65℃, warm the mill for several minutes under this condition, start the lubrication station, start the hydraulic station, lift the grinding roller, and start the mill motor; 4. Adjust the actual opening of the mill inlet regulating valve and circulating air valve by +20% to meet the requirement of -100Pa<P LT <-10Pa+T MC When the temperature is less than 65℃, the actual opening value of the mill inlet regulating valve and circulating air valve is increased by 20%. After the valve position is in place, under the adjustment of the flue gas furnace automatic pressure stabilization, the flue gas furnace vent valve gradually increases from 100%, 65%, 30%, 0% until it is closed; 5 When T MC >65℃, start the flue gas furnace temperature sending program; when T MC When the temperature is higher than 70℃, start the coal feeder belt and cleaning chain, and set the coal feeder flow rate to L SD Through PID control, the actual flow rate reaches the approximate set value. After a delay of 5S, the grinding roller is dropped and pressure is applied to start pulverizing. The automatic control program of the mill outlet temperature and the flue gas furnace pressure stabilization program are put into operation. While adjusting the outlet temperature, the automatic control program of the mill outlet temperature automatically increases the coal feeder flow rate to near the hourly output.

8. The fully automatic control system for pulverized coal preparation equipment according to claim 7, characterized in that: The start-stop sequence control unit of the milling equipment controls the equipment to stop as follows: When the pulverized coal bin level is greater than the upper limit, the system will automatically shut down after a delay of 40 seconds, and the flue gas furnace will enter the insulation program. The mill outlet temperature T MC Furnace temperature of flue gas furnace T LT The program enters the 5S interval flue gas furnace voltage stabilization and mill outlet temperature limit control; First, collect the hysteresis T MC T2 temperature sampling value at intervals of 5S; when T MC <T2-ΔT condition but satisfies T2-ΔT<T MC <T2+ΔT condition, ΔT is the temperature deviation value, adjust the mill inlet regulating valve and circulating air valve opening to reduce by 1%; when T is not met MC <T2-ΔT condition but satisfies T MC >T2+ΔT, adjust the coal feeder flow setting value to increase the coal feeder flow adjustment constant ΔL to promote T MC Decrease until T MC <T2-ΔT condition holds; When T is satisfied MC When the condition is less than T2-ΔT, the coal feeder flow setting value is reduced by the flow adjustment constant ΔL, and then adjusted again after 5S interval until the shutdown safety condition is reached (coal feeder flow L SJ ≤20% of the measuring range + mill outlet temperature T MC <60℃; When the shutdown safety conditions are met, open the cold air valve, open the flue gas furnace vent valve, close the circulating air valve, close the mill inlet regulating valve, wait for the mill current to reach the no-load value, lift the grinding roller, stop the mill motor, stop the hydraulic station, stop the main induced draft fan, and wait for the main induced draft fan flow to be less than 1000NM 3 / h, the mill separator is shut down, the bag box backflush system is shut down with a delay of 200S, the air lock ash unloading valve is shut down, the coal powder vibrating screen is shut down, the cold air valve is closed, the main exhaust valve is closed, the mill emergency nitrogen filling is turned on and closed after 2 minutes, and the system shutdown is completed.

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