In recent years, various sinter plants have paid more and more attention to the overall management automation problem. The distributed control system (DCS), which combines automation of management information system and automation of production process, has become the mainstream of old factory renovation and new plant design. At present, DCS is widely used in various large and medium-sized sintering plants and plays an increasingly important role in production. It is characterized by overcoming the singularity and limitation of the function of the analog instrument, and avoiding the danger of high concentration of computer control. It has flexible structure, convenient expansion and high reliability.
Domestic and medium-sized sinter plants to burn the new four Baoshan Steel Corporation three iron sintering and engineering company Wuhan Iron and Steel Group, represented by new modern sintering plant, sinter machine the size of their respectively 450m ² and 435m ^2. In this paper, in order to The two are examples of the application status of sintering process detection and automatic control at the domestic leading level.
The automation system of the sinter plant is divided into two levels: equipment control level and process management level integrated by machine, electricity and gas. The equipment control level includes direct digital control (DDC) and electrical sequential logic control (PLc) of the instrument, which not only completes the automatic measurement and continuous control of various process quantities, but also completes the chain and program of various process equipment start and stop. control. The process management level mainly processes and processes all the production process information sent by the device control level by the process management computer, prints it into various production reports, and performs data communication with the regional computer or other unit process machine.
According to the characteristics of the sintering process, the sintering process is divided into raw material preparation system, batching system, mixing system, sintering system, cooling system, finished product management system, waste heat recovery and main exhaust system, dust removal and water treatment system, etc. Implement decentralized control and centralized management. The main detection and control functions are shown below.

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(1) Raw material preparation system The number of sintering raw materials is large, the variety is varied, and the particle size and chemical properties are extremely uneven. Fluctuations in the characteristics of raw materials are a factor that cannot be ignored in the instability of sintering production. The use of advanced methods and techniques to enhance the detection and automatic control of the raw material preparation stage can greatly reduce the effect of raw material changes on sintering.
In the raw material preparation system, the main testing and control items are the detection of the material level of each trough (including the coarse flux tank, the flux crushing chamber ore tank, the flux screening chamber ore tank, the coarse fuel tank, the coarse fuel crushing tank, and the fine fuel crushing). Slot), the signal is sent to the computer, the upper and lower limits of the material level are alarmed and sent to the electrical chain. The level detector used in the system is a heavy hammer level gauge.
(2) The batching system batching system detection and control projects are:
(1) Automatic detection of the material level of the ore tank and selection of various raw material distribution schemes. The batching ore tank adopts the weighing type level meter and the heavy hammer type level meter for continuous level measurement, sends the signal to the computer, and uses the capacitive level switch for the level limit detection, alarm and chain; in most sintering plants, The mine plan generally relies on expert experience to refer to previous ore blending examples, and adjusts according to the feedback situation of the sinter, which has greater blindness. The application of a neural network-based ore expert system developed by Baosteel recently shows that this idea and technology are more suitable for the problem of ore blending.
(2) Raw material discharge control. The automatic batching uses the quantitative disc feeding control device and the belt scale for raw material batching. Multiplying various raw materials by a certain compounding coefficient and multi-feeding amount set value, and then outputting an operation signal by the control unit to drive the cutting device to realize automatic control of dosing, flux, fuel compounding, and metering, Accumulated and limit alarms.
(3) Automatic measurement, display, recording, upper and lower limit alarms of fuel moisture and raw material moisture, sending signals to computers and electrical interlocks.
(3) Hybrid system
The detection and control of the mixed system is mainly the detection and control of the water volume of the first and second mixers. The water pressure and low pressure alarm are added, and the signal is sent to the computer and electrical chain.
The detection and control of moisture is a difficult point in the sintering operation. The standard value and error range of the moisture of the mixture are strictly controlled to improve the gas permeability of the mixture and to suppress the excessively wide wet band. Commonly used detection methods are: thermal drying method, neutron measurement method, rapid weight loss method, infrared measurement method and conductance method. Among them, the thermal drying method and the rapid weight loss method are batch type determination methods, and in order to realize rapid on-line continuous measurement of moisture, a neutron method, an infrared method, and a conductance method are required. More neutron moisture meter and infrared moisture meter are used in the field. The mixed water flow rate is measured by an electromagnetic flowmeter and adjusted by a pneumatic diaphragm regulating valve. The sintering mixture detection and intelligent control system adopted by the second ironmaking plant of Benxi Iron and Steel Co., Ltd. combines the feedforward fuzzy control and the feedback expert control, and the control target reaches the moisture content of the mixture within the range of (7.0 soil 0.5)% standard deviation.
The mixing trough material level is automatically measured, displayed and alarmed by weighing full fulcrum method, and the signal is sent to the computer, which is controlled by computer and electrical interlock. The material level is continuously and automatically controlled according to factors such as the input material volume, the discharge amount and the measurement signal of the material level.
(4) The sintering system sintering system includes the bottoming material cloth, the mixed material cloth, and the ignition and sintering joint. The main items tested and controlled are:
(1) Automatic measurement and control of the material level of the bottoming trough. That is to say, the weighing level is automatically measured by the weighing analog fulcrum method to display the alarm. According to the feeding belt conveyor speed, the sintering machine speed and the feedback signal of the material level, the integrated operation processing is performed. The output signal of the adjusting unit controls the motor rotation number, and the belt conveyor speed is changed to change the feeding amount to realize the automatic material level control.
(2) Sintering machine speed control. That is, the detection signal of the tail section and the bellows exhaust gas temperature observed by the industrial television estimates the state of the sintering end point, and adjusts the machine speed in combination with the temperature signal of the main exhaust flue. At present, the speed of the sintering machine is manually set in the remote position at the operation station, and the speed of the ring cooler and the plate feeder is controlled in linkage according to a certain speed ratio. [next]
(3) Layer thickness control. The thickness control of the material layer consists of three parts: the main gate opening degree, the auxiliary gate opening degree and the round roller feeder speed control. Six auxiliary gates are arranged along the width direction on the side of the main gate, and respond to six independent automatic control systems. Each system performs constant value feedback control according to the layer thickness signal to keep the horizontal thickness of the trolley uniform. According to the average value of the six layer thickness signals, the round roller speed is feedback controlled to adjust the longitudinal feeding amount of the trolley to meet the requirements of the longitudinal layer thickness. According to the change of the speed of the round roller feeder, the operation signal is output through the operation, the opening degree of the main gate is automatically controlled, and the feeding amount is adjusted in coordination with the round roller. In addition, there is automatic monitoring and control of the liquid level, oil temperature and oil pressure of the oil pressure source device for layer thickness control.
(4) Ignition furnace combustion control. Ignition furnace combustion control includes furnace pressure, temperature detection, ignition intensity and ignition temperature control. The pressure in the ignition furnace and the pressure of the first bellows are automatically measured, displayed, and alarmed, and the signal is sent to the computer. According to the pressure signal, the opening degree of the No.1 bellows branch pipe is adjusted, and the suction pressure is changed to realize the automatic pressure control in the furnace. The furnace temperature is automatically measured and displayed, and the signal is sent to the computer. A combustion furnace feed point automatic measurement gas and coal with air flow, alarm and control signals sent to the computer. The ignition intensity is controlled according to the heat required for burning per unit area of ​​the loading layer of the trolley. Cascade temperature control based on furnace temperature. Automatic measurement of gas mains pressure, display alarm and automatic control, and automatic low pressure cutoff.
(5) Automatic detection and calculation of the number of trolleys, and send the signal to the computer.
(6) Automatic measurement and display of bellows exhaust gas temperature and bellows pressure, and send the signal to the computer. The air box exhaust gas temperature is a direct reflection of the thermal state of the sintering process. The bellows pressure can indirectly reflect the change of the gas permeability of the material layer. The detection of these two parameters is the key to realize the automatic control of the sintering machine. However, due to the lack of a sintering machine control model based on thermal state parameters, automatic control of the speed of the sintering machine has not yet been achieved.
(7) Calculation processing of the sintering end point. The sintering end point (BTP) is the position of the burning point of the loading layer of the trolley. It is generally considered that when the sintering action reaches the end point, the exhaust gas temperature reaches the highest value. In actual production, the BTP value is calculated according to the exhaust gas thermometers of the last three bellows, displayed, and sent to the computer.
(8) Automatic measurement, display, alarm of the main exhaust pressure at the sintering machine room, and send the signal to the computer.
(9) The cooling water flow rate of the hot crusher , the automatic measurement and alarm of the flow rate, pressure and return water temperature of the cooling water for the ignition furnace and the holding furnace. (10) The temperature and flow rate of the holding furnace, the residual heat air flow for the combustion furnace, and the automatic measurement, display and alarm of the auxiliary burner air pressure and send the signal to the computer.
(5) Cooling system
Large-scale sinter plants mostly use ring chillers. The detection and control projects include the measurement, display and alarm of the flue gas temperature and discharge temperature of the ring chiller. The number of revolutions of the ring chiller is automatically controlled according to the discharge temperature signal, and the air volume is changed. To regulate the discharge temperature. The analog fulcrum method is used to automatically measure, display and alarm the level of the discharge tank, and automatically control the speed of the plate feeder according to the material level detection signal to keep the level of the discharge tank within the allowable range.
(VI) The products of the finished product management system for the inspection and control of the finished product management system include the automatic measurement, display, integration and alarm of the bottoming material, returning mine, finished product output, finished product distribution, sending the signal to the computer, and sending the electricity to the material. Distribution control.
(7) Waste heat recovery and main exhaust system
The measurement, display and exit temperature alarm of the inlet and outlet temperatures of the hot air precipitator automatically adjust the opening of the cold air valve according to the wind temperature detection signal at the outlet of the hot air precipitator to control the air temperature. According to the hot air flow signal required by the ignition furnace and the holding furnace, the number of revolutions of the waste heat recovery fan and the opening degree of the inlet valve of the fan are controlled, and the hot air flow is adjusted accordingly. The waste heat recovery and main exhaust system detection and control projects have the measurement, display and alarm of the temperature and pressure of the exhaust heat recovery fan outlet, the automatic measurement of the main exhaust temperature, pressure and flow at the inlet of the main exhaust fan, display the alarm, and send the signal computer.
(8) Dedusting and water treatment system Dedusting system detection and control project Organic head, tail, batching, finished product Dust removal inlet gas pressure, temperature, flow rate, outlet gas dust concentration, automatic measurement of dust tank level, display alarm ; powder coke bag dust removal inlet gas pressure, flow, outlet gas pressure detection, display, alarm, send signals to the computer, dust tank level alarm. Detection point is provided on the 200m high chimney, flue gas emissions of NO _x, SO _x, CO _x content of the automatic measurement, a display, an alarm, a signal sent to the computer.
The water treatment system detects and controls the industrial water pressure, conductivity, flow measurement, display, the flow signal to the computer, the circulating water cooling pool level, the cooling water conductivity, the cooling water temperature automatic measurement, display and alarm, according to The cooling water temperature adjusts the number of cooling fan revolutions to control the cooling water temperature.

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