SU1211575A1 - Method of automatic control of clinker roasting process in rotating furnace - Google Patents

Description

The invention relates to methods for the automatic control and sintering of clinker in rotary kilns and can be used in cement industry.

The aim of the invention is to improve the control accuracy.

The method is illustrated by the example of burning clinker in a rotary kiln with a grate cooler according to the wet production method. The essence of the described method can be understood / as follows.

To control the firing process, it is necessary to form an optimal torch structure. A short and remote from the exit edge of the kiln flame causes a decrease in lining durability, while due to the fact that the sintering zone is removed from the exit edge of the kiln, an already finished clinker in the kiln is overexposed. .kodilnika.

On the other hand, the formation of a torch that is too long in the logo leads to the burning of the nozzle, the deposition of refractory bricks and threshold plates at the hot end of the furnace.

An important factor in controlling the firing process of a pincher in rotary kilns with a grate cooler is to maintain the optimal enthalpy value of the secondary air supplied from the cooler to the combustion zone. In general, the enthalpy of all the secondary air supplied to the furnace can be determined from the ratio

Q; (

,, GEN ,, iEb. vg ,, tv at 6 tg bc,

sharp

where G /, G

OSbl,

ie

vg

(one)

-respectively, the masses of air acute total blowing supplied

in the refrigerator for cooling the clinker, and excess, discharged from the refrigerator, kg / h;

- secondary air temperature. WITH;

ten

13752

C is the heat capacity of the secondary air, kJ / kg.

5 The enthalpy of secondary air supplied to the kiln per 1 kg of clinker can be determined from the ratio

q Q; / Gn, (2)

where GI, is the productivity of the furnace according to clinker, i.e. amount of clinker entering the refrigerator, kg / h.

15 The optimum enthalpy of air supplied from the refrigerator to the combustion zone is determined by the maximum value of the efficiency of the refrigerator (0.57 - 0.85) and is equal to 9002CI 1050 kJ / kg. At these temperatures, an optimal plume structure is formed, i.e. its shape, d.pina, heat stress. This is explained by the fact that at lower

The 25 enthalpy values of the total air supplied to the combustion zone decrease to 300 ° C, displacing the cold edge of the furnace and the ignition point.

JQ Combustion of T (5 fuel takes place on a short heat-stressed and remote from the hot cut edge of the furnace. Higher enthalpy value (over 1050 kJ / kg) is difficult in practice, and the temperature of the secondary air supplied to the combustion zone rises to 500 600 C, which is close to the ignition point of the fuel. This means that the fuel ignites near the mouth of the nozzle, which is also unacceptable. The position of the point with the maximum thermal stress can be changed by the amount of excess air supplied to the combustion zone The amount of excess air in the combustion zone can be regulated by baking smoke exhausters.

It has been established that when a clinker barked, the point with the maximum temperature of the furnace body should be at a distance of 6-10% of the length of the furnace from its hot cut. Fluctuations in the temperature and volume of air supplied to the combustion zone, changes in the physicochemical parameters of firing- Moi o feedstock and other parameters require continuous adjustment.

35

40

five

3

the shape and structure of the torch, and hence the temperature.

An implementation scheme for mathematical control is shown in the drawing.

The method includes supplying and burning fuel in the furnace 1 through the nozzle 2, supplying hot secondary air from the grate refrigerator 3, supplying cold air sharply from the fan 4 under the fixed grate 5 of the refrigerator, and blowing cold air from the fan 6 under the moving grate 7 refrigerators, regulation of the amount of cold air supplied to the refrigerator by gates 8 and 9, regulation of the amount of air emitted from the refrigerator as excessive by gate 10 of the exhauster 11, regulation of excess air in the combustion zone of the chimney 12 of the baking smoke exhauster 13, measuring the temperature of the furnace body 1 with the aid of a radiation pyrometer 14 mounted on a mobile carriage 15, measuring the amount of oxygen in the exhaust gases by the sensor 16 installed in the cooling chamber 17, measuring the temperature of the secondary air sensor 18 installed in the shaft of the refrigerator 3 The automatic control of the clinker burning process in a kiln is carried out using two control loops. The first circuit performs continuous automatic control of the position of the point with the maximum temperature of the furnace body using a radiation pyrometer 14, a gate 12, a smoke exhauster 13 and a former 19. The control signal in this circuit is a signal 20, which comes from the former 19. Differentiation of the signal from the radiation pyrometer 14, and determination of the distance from the point with the maximum temperature to the hot edge of the furnace.

The position of the point with the maximum temperature is controlled as follows. The control signal from the radiation pyrometer, which characterizes the temperature value of the furnace body, is fed to the imaging unit 19.

1 S 7 5

In Shaper 19, the point with the maximum temperature value is determined using a differentiation unit and the distance from this point to the 5 output edge of the furnace, then the received signal 20 is fed to the comparison device 21, where it is compared with the signal coming from the gate position 22 smoke exhauster

0 and a signal characterizing the oxygen content in the exhaust gases. A controller 23, an actuator 24, and a comparison device 25 are also included in this circuit. A comparison device 25 is supplied with a signal from sensor 16, which measures the oxygen content in the exhaust gases, and a signal from the transmitter 26, which characterizes the oxygen content in the exhaust gases.

If the point with the maximum value is (the peruraura is at a distance greater than 10%, then the control system changes the position

5 gate 12 of the exhauster 13, while reducing the vacuum for cutting the cold part of the furnace. As a result, the point with the maximum value of thermal stress shifts towards the hot edge.

0 furnace, If the point with the maximum temperature of the furnace body is located closer than 6% of the length of the furnace, the control system by the gate 12 of the exhauster 13 increases the vacuum behind the edge of the furnace.

The second circuit provides continuous automatic regulation of the enthalpy of hot (secondary) air supplied

0 from the refrigerator to the burning zone. Regulation in this circuit is carried out as follows. Signals from actuators 28 are supplied to computing device 27,

5 29 and 30, characterizing, respectively, the position of the gates 8, 9 and 10 of the fans 4, 6 and 11 of acute, common and aspiration (excessive) blow. These signals characterize

0 respectively volume expenses

sharp

V

OEbJ,

V

Hb

mh / h

spirit, V g,. g,. g

The device 27 is supplied with signals characterizing the temperatures from the ambient air resistance thermometer 31, from the excess air temperature sensor 32, and a signal from the former 33, which characterizes the amount of clinker entering the grate. Based on the volume flow rates V,

,, sharp ,,

Vg, Vg, ambient air temperatures and excess air are determined respectively by the mass of total G, acute G and excess air. As a result

In an EE1 calculation of secondary air from the relations (1) and (2), the computing device 27 generates a control signal that is fed to the comparison device 34. The comparator 34 also receives a signal from the air flow defining unit 35 for a sharp blow. The resulting control signal is fed to the controller 36 and then to the actuator 28, which changes the position of the gate 8 of the fan 4 of a sharp blow. In this case, if the enthalpy value of the secondary air exceeds the maximum permissible value of 1050 kJ / kg, the comparison device 34 receives corrections to the signal — an increase in the amount of air blown sharply: if the secondary air enthalpy is below 900 kJ / kg, the comparison device 34 is supplied a correction signal to reduce the air flow of an acute blow; The automatic control scheme provides for a stable air supply of the total blow which is set by the control 37 by the regulator 38 and the performer mechanism 29, and stabilized excess air blowout by fan 1I with the help of a knob 39, a regulator 40 of the actuator 30, and a gate 10.

The optimum position of the point with the maximum temperature of the furnace body is the position at a distance of 6-10% of the length of the furnace from the output edge, preferably 9j, 1%. To achieve this position, the enthalpy of secondary air must be maintained within 900-1050 kJ / kg, and the oxygen content B of the exhaust gases — 0.8-2.0%. The maintenance of the specified limits is carried out as follows.

The signal, n from the radiation pyrometer 14, characterizing the value of the temperature of the furnace body, goes to the imaging unit 19, where the point with the maximum temperature and the distance from this point to the output edge of the furnace is determined. The received signal 20 is supplied to a comparison device 21, which also receives signals from the comparison device 25 and the setting unit 22 of the position of the chimney damper.

Example 1, the point with the maximum value of the body temperature is at a distance greater than 10% of the furnace length from the cut-off. In this case, the comparison device 21 is connected to the regulator 23 and the actuator 24 is given a correction signal to change the position of the spindle 12 of the exhauster 13 for reducing the vacuum across the cold end of the furnace. At the same time, the computational device 27 of the secondary control loop calculates the enthalpy value of the secondary air, which can either be in the optimal range, or, as in this case, be lower than 900 kJ / kg. The device 27 generates a control signal that is fed to the device 34. compare. The comparator 34 also receives a signal from the unit 35 for setting the air flow rate to blow sharp. From the comparison device 34, a control signal is transmitted to the regulator 3 and the actuator 28, which by changing the position of the gate 8 of the fan 4 reduces the amount of cold, sharp air blowing.

EXAMPLE 2. A point with a maximum, with the increase in the temperature of the body, is located at a distance less than 6% of the length of the furnace from the EE of the cutting edge. In this case, from the comparison device 2t, the regulator 23 and the actuator 24 are supplied with a correction signal to change the position of the slider 12 of the exhauster 13 to increase the vacuum pressure after the cold end of the furnace. The enthalpy value of secondary air5 calculated in device 27 can either be in the optimal range, or, as in this case, be higher than 1050 kJ / kg. If the enthalpy value is above 1050 kJ / kg, then device 27 generates a signal that is transmitted to comparison device 34, where the signal from block 35 also arrives.

7

Set air flow rate for sharp blowing. From the comparator device 34, a control signal is transmitted to the controller 36 and the actuator mechanism 28, which by changing the position of the gate 8 of the fan 4 increases the amount of cold, sharp air blowing.

Thus, maintaining the position of the point with the maximum body temperature at a distance of 6-10% of the length of the furnace from the edge of the cut-off is to ensure the value of the enthalpy of secondary air within 900-1050 kJ / kg and the oxygen content in waste

115758

gases in the range of 0.8-2.0%. In the case when the point with the maximum value of the body temperature is located outside 6-10% of the length of the output edge of the furnace, a change in its position is achieved either by changing the enthalpy of the secondary air or by changing the amount of oxygen.

10 in the exhaust gases, or by simultaneously changing the values of the specified parameters.

Thus, efficiency and quality are improved.

15 control, which creates optimal conditions for the granularity of the clinker while reducing fuel consumption.

Claims (1)

METHOD FOR AUTOMATIC CONTROL OF THE CLINKER FIRING PROCESS IN A ROTARY FURNACE, which includes continuous measurement of the furnace body temperature along the sintering zone, changing the sharp air flow rate to cool the clinker and changing the position of the smoke exhauster gate, so that In order to improve control accuracy, measure the amount of clinker entering the refrigerator, the ambient air temperature and excess air, the position of the gates of the fans of acute, general and aspiration blasting, the oxygen content Yes, in the exhaust gases and on the basis of these parameters, the enthalpy of the secondary air supplied to the furnace for burning fuel is determined, and the distance from the furnace inlet to the point with the maximum temperature of the furnace body is determined, moreover, the air flow rate of sharp blast for cooling the clinker is carried out until the enthalpy is reached secondary air values of 900 1050 kJ / kg, and the change in the position of the gate of the exhaust fan is carried out until the distance from the furnace inlet to the point with the minimum temperature of the furnace body reaches th 6 10% of the length of the furnace. J7