SU1697883A1 - Automatic control system for a ball-tube mill operating at its maximal efficiency - Google Patents

Abstract

The invention relates to the automatic regulation of dust preparation plants with ventilated ball drum mills, can be used to optimize the dust systems of thermal power plants and will improve the control accuracy and reliability of the drum mill. It contains a stabilizer regulator 7 for the flow rate of the drying agent, a regulator stabilizer 8 for the air-mix temperature behind the mill, regulator 9 for the maximum load of the mill, sensor 10 for the rotational speed of the raw material feeder, unit 11 for the minimum rotational speed of the raw coal feeder, integrator (L C dust bin

Description

Cold bozduh

FIG I

12, a manual control unit 13 regulating the pulse device 14, the setting unit 15 of the maximum rotational speed of the raw coal feeder, the dust consumption sensor 16 behind the separator, the adder 17, the nonlinear element 18, the integrator 19, the analog-discrete converter 20, the elements 21 and 22, analog-discrete converter 23, adder 24, analog-discrete converter 25, adder 26, trigger 27, element AND 28, element OR 29, elements And 30 and 31. 2 Il.

The invention relates to the automatic regulation of dust preparation plants with ventilated ball drum mills. It can be used to optimize the dust systems of thermal power plants.

The aim of the invention is to improve the control accuracy and reliability of the operation of the drum mill.

FIG. 1 is a block diagram of the system; on figa, b - the temporal characteristics of the dust consumption for the separator.

The dust preparation plant contains a raw coal bunker 1, a raw material feeder 2 with a DC electric motor 3, a ball drum mill 4, a separator 5, a cyclone 6, a drying agent regulator 7, a drying agent regulator, and a regulator 8 for the mixture of an air mixture using a mill. The system contains a regulator 9 for maximum loading of a ball drum mill 4, a sensor 10 for the rotational speed of the raw material feeder, a setting device 11 for the minimum rotational speed of the raw coal feeder and an integrator 12, a manual control unit 13 for regulating a pulse device 14, a setting device 15 for the maximum rotational speed of the feeder raw coal, dust consumption sensor 16 behind separator, adder 17, nonlinear element 18, Integrator 19, first analog-discrete Converter 20, And 21 and 22 elements, Itera analog-discrete converter 23, adder 24, three s analog-to-digital converter 25, an adder 26, RS-flip-flop 27, AND gate 28, an OR gate 29, AND gates 30 and 31.

The system works as follows.

The system is put into operation immediately after turning the mill 4, and loading the mill with coal. The regulator 9 of the maximum mill load, acting on the electric motor 3 of the raw coal feeder 2, sets its rotation frequency in accordance with the minimum setting. The regulator stabilizer 7 establishes a constant flow rate of the drying agent through

the mill, and the stabilizer-regulator 8 of the aero-mix temperature behind the mill sets a constant temperature behind the mill.

When the manual control unit 13 is turned on, the automaton appears logical 1 at the first input of the element 31, and the signal from the output of the regulating pulse device 14, at the input of which

the difference between tasks 11 and 15 is established, is fed to the second input of integrator 19, and the mill begins to be charged with coal by increasing the frequency of rotation of the raw material feeder 2 to the maximum setting.

As the mill is loaded, its drum is not overfilled with coal, i.e. filling it has not passed the critical point, the dust output from the mill grows and the signal from the output of the sensor 16 dust consumption behind the separator grows, then

the difference at the output of the first adder 17 is positive and it goes through the nonlinear element 18 to the first input of the integrator 12. Mill 4 was saturated with coal, the dust consumption behind the separator passed the critical point and the readings of sensor 16 began to decrease. A negative signal appears at the output of the adder 17, which does not pass through the nonlinear element 18, and the logical analog 1 goes through the first analog-discrete converter 20 to the first inputs of the elements 21 and 22, and since the signal from the raw carbon feeder 10 is close to the maximum reference, then through the second analog-to-discrete converter, logical 1 is fed to the second input of the And 21 element. Consequently, logical 1 from the output of the And 21 element goes to both inputs of the And 28 element and logical 1 from its output through

the OR element 29 is fed to the second input (zeroing) of the integrator 12 and resets it, preparing it for determining the next search step, and logical 1, coming from the output of the AND 21 element via the S input

RS-flip-flop 27, is fed to the first input of the element And 31, and logical 1 from the output of the element And 31, arriving at the first input of the integrator 19, resets the maximum

setting the maximum efficiency of the mill from the input of the regulator 9, Mill 4 begins to unload, the rotational speed of the raw coal feeder is reduced to the minimum setting, the mill begins to thicken and at the initial moment the dust output behind the separator 16 begins to increase. At the output of the adder 17, a positive difference appears, which through the nonlinear element 18 enters the first input of the integrator 12, but as the mill is exhausted after the critical point, the dust consumption behind the separator 16 begins to decrease and at the output of the adder 17 there appears a negative difference The first analog-to-discrete converter 20 to in, the logical 1 is fed to the first inputs of elements 21 and 22. But, since at this moment the rotational frequency of the raw coal feeder is close to the minimum reference, then logical 1 to the second input of the second element AND 22 through the third analog-discrete converter 25 and the logical 1 from the output of the second element AND 22 enters the R-input of the RS flip-flop and resets its direct output. Consequently, the maximum reference enters the input of the maximum load controller 9 through the pulse control device 14, the manual control unit 13 and the integrator 12, and the mill starts to be charged with coal by increasing the rotation frequency of the raw coal feeder. Logic 1 from the reverse output of the RS flip-flop 27 and logical 1 from the output of element 22 causes the appearance of logical 1 at the output of element 30, which through element OR 29 enters the second input (zeroing) of integrator 12, preparing it for determining the next search step and the process is repeated.

Fig. 2a shows the temporal characteristics when the regulator operates under stable grinding conditions (constant grindability of coal, constant moisture of coal, ball loading does not change, etc., let's call this generalized grinding conditions and denote o). As can be seen from the nature of the transient process, the dust consumption behind the selector fluctuates around its maximum value due to the grinding conditions within the search zone, which is defined by the dead zone at the first analog-discrete converter 20. The rotation frequency of the raw coal feeder in this case varies from max to min.

Fig. 26 shows the temporal characteristics of a change in the dust consumption behind the separator when the grinding conditions change abruptly (dry soft coal has gone, new balls are poured, etc., i.e., it has also changed stepwise).

The system of automatic control of the maximum performance of a ball drum mill ensures the stability of the control process at any high drift velocity of the extremum.

Claims (1)

Claims of the Invention A system for automatically controlling the maximum performance of a ball drum mill working in conjunction with a separator, comprising a controller for maximum mill loading, the output of which is connected to a raw material feeder motor, characterized in that. that, in order to improve the control accuracy and reliability of the drum mill operation, the rotational speed sensor of the feedstock motor, three adders, a nonlinear element, three analog-discrete converters, two integrators, five AND elements, an OR control element, a pulse device, were inserted into it; control devices for the minimum and maximum rotational speeds of the electric motor for the feedstock feed, manual control unit, dust consumption sensor behind the separator, RS trigger, the dust consumption sensor after the separator connected the first input of the first adder, the output of which is connected to the input of the first analog-discrete converter and the input of the nonlinear element, the output of which is connected to the first input of the first integrator, the output of which is connected to the second input of the first adder, the output of the first analog-discrete converter is connected to the first inputs of the first and the second element And, the output of the second ana-disk converter is connected to the second input of the first element And, the output of which is connected to the first input of the RS flip-flop and the first input of the second element AND, the output of which is connected to the first input of the element OR, the output of which is connected to the second input of the first integrator, the output of the third enal-discrete converter is connected to the second input of the second element AND, the output of which is connected to the second input of the RS flip-flop and the first input of the fourth element And, the first output of the RS-flip-flop is connected to the second input of the fourth element And, the output of which is connected to the second input of the OR element, the second output of the RS-flip-flop is connected to the second input of the third element And and the first input of the fifth element I, the output of which is connected to the first input of the second integrator, the output of the regulating pulse device is connected to the input of the manual control unit, the first output of which is connected to the second input of the fifth element And, the second output of the manual control unit is connected to the second input of the second integrator which is connected to the first input of the controller of the maximum load of the mill and to the first input of the regulating pulse device, the setpoint of the minimum frequency of rotation of the electric motor of the raw material feeder is connected to the first input of the regulator of the maximum load of the mill, with the second input of the regulating n fit. “„ but) five pulse device and with the first input of the second adder, the second input of which, the first input of the third adder and the third input of the maximum mill load controller are connected to the rotational speed sensor of the raw material feeder motor, the maximum speed frequency adjuster of the raw material feeder motor is connected to the second input of the third adder and with the third input of the regulating pulse converter, the output of the second adder is connected to the input of the third analog-discrete converter, and the output of the third ummatora connected to the input of the second analog-to-digital converter. R