SU992596A1 - Method for automatically controlling electrical ore furnace having even number of electrodes - Google Patents

Description

This invention relates to automating the electrical and thermal conditions of ore-smelting furnaces, e.g. ferroalloy.

A method is known which involves maintaining the same active power and active component of the voltage on each electrode of the same phase Cl.

There is a known method in which the issues of regulating the active power on the electrodes with current limitations of the electrode C2 are solved.

However, this creates conditions for a different embedding of the electrodes of the same phase, which leads to a heterogeneous thermal field of the bath; especially with the segregation of charge materials, which in practice often takes place.

Closest to the present invention is a method for adjusting a six-electrode furnace according to the active resistance under the electrode and the active power of the C 3 phase.

In this method, restrictions are placed on the movement of the electrode according to the position of the electrode holder and the gas temperature under the furnace roof. When controlled by this method, due to the inequality of the conductivities of the charge materials, a different depth of the electrodes of the same phase is observed. In addition, a change in resistance under one electrode causes a change in the current in the circuit consisting of two electrodes. The presence of an arc under the second electrode leads to a change in the resistance of this arc. In this case, the regulator will move both electrodes, although a disturbance occurred only on one electrode. Such unnecessary movements of the electrodes degrade the structure of the melting space and reduce the technical and economic performance of the process.

Thus, the known methods of regulation do not ensure uniformity of the thermal floor of the smelting

20 spaces and lead to unnecessary private movement of the electrodes.

The purpose of the invention is to stabilize the melting mode due to a more uniform heat supply in the furnace's melting space and to reduce the number of movements of the electrodes.

The goal is achieved by using known methods as

30, moving the electrodes and switching the voltage levels of the transformer, depending on the electrode current, changes the position of one or both electrodes in a predetermined interval depending on the sign and the value of the difference in voltage drops across the electrodes in the direction of eliminating the deviation, and or temperature, the voltage steps of the transformer of this phase are switched. Also, when the current decreases, the electrode with a higher voltage drop is lowered By contrast, when the current is lowered, the electrode is lifted with a smaller voltage drop, and if the voltage drops across the electrodes, the mode is controlled by both electrodes.The regulation is carried out by testing the current deviation of the electrode from the set electrode displacement or switching the voltage of the furnace transformer of this phase The elimination of the current deviation by moving the electrodes is performed depending on the voltage difference across the paired electrodes of the phase. The voltage drop across the electrodes of the same phase more reliably characterizes their relative depth. This is due to the fact that with the deepening of the electron, the flow decreases both the active and the inductive components of the resistance of the electrode and vice versa. Monitoring the difference in voltage drop across paired electrodes allows determining their relative depth and choosing the correct control effect. To increase the current, the electrode on which a greater voltage drop is lowered is applied. Accordingly, to decrease the current, the electrode is raised with a smaller voltage drop. In case of equality of the PII of the scientific research institute of voltages, the working is carried out by both electrodes. If necessary, the asymmetry of voltage drops can be specified while maintaining the stated law of regulation. The movement of the electrodes as a regulating effect is used if the position of the electric holders and the temperature of the gases under the roof are in the established boundaries. Otherwise, the testing of the current deviation is carried out by switching the voltage of the furnace transformer towards the elimination of the deviation. This restriction on the movement of the electrodes is associated with the need to introduce energy into a given area of the filling space, which will provide a higher energy efficiency of the installation. The uniformity of the thermal field within this region provides for the displacement of the paired electrodes depending on the distribution of the Pade-NII voltage on them. The method is implemented by various devices and systems. The drawing shows a block diagram that implements the method of automatic control. In the block diagram, the output of the current transformer (A) (TT) of the paired electrodes is connected to the first input of the comparison unit 1, the second input of which is connected to the output of the electrode current setting unit 2. The output of block 1 through delay element 3 is connected with the first input of logic unit 4. The second input of block 4 is connected with the output of comparison block 5 - voltages on the first and second electrodes B and C through delay element 6. Sensor outputs (D, D) The positions of the electrodes (D P1 and C P2) are associated respectively with the first inputs of the comparison units 7 and 8, the second inputs of which are connected to the output of the unit 9 defining the working area of the movements of the electrodes. The outputs of blocks 7 and 8 are connected respectively to the third and fourth inputs of logic unit 4. The temperature sensor E (DT) output under the roof is connected to the first input of the comparison unit 10, the second input of which is connected to the output of the block 11 for setting the permissible operating temperature under the roof . The output of block 10 through the transponder element 12 is connected to the fifth input of logic unit 4. The first output of logic unit 4 via amplifier 13 is connected to the actuator 14 for moving the first electrode, and the second output of block 4 through the amplifier 15 is connected to the actuator 16 for moving the second electrode. The third output of unit 4 through the amplifier 17 is connected to a switch of 18 steps, the voltage of the furnace transformer Ж (ПТ). The fourth output of block 4 is associated with the information board 19. Delay elements 3, 6 and 12 are designed to filter out random short-term disturbances that the device has not been processed. The device works as follows. At the output of block 4 six control and one information signals are formed: P1 - rise of the first electrode; 01 - lowering the first electrode; 02 - rise of the second electrode; 02 - lowering the second electrode; PN — voltage increase of the furnace transformer; CH - voltage decrease of the furnace transformer, And violation of the technological mode.

The formation of control and information signals is carried out

at

& :) o,,, e.,; with,, g BN, with,,,, with; at

,, C “if 7, o

& 2 E {if.

or ri

g E Oh, C / VC, if 4 and: j O

2 6 bs: li,

or and

4J Oh, le7 / 0, B e „, if, o

2 e, if 4U and.

Is where D E Eel -; L in e - Q li. When the electrode current deviates from the given value Dj, the error signal AZ will go to the logical unit 4. At the same time, the voltage difference signal from the second electrode (U-j-Uj) will come from block 4 compared to voltage drops 5 in block 4. If the electrodes are in the working zone of movement and the gas temperature under vault 9 is less than the permissible value QsdA 1 ° depending on the signs of d3 and di at the output of block 4, the signals are in the signal and one or two electrodes will move towards the elimination of the deviation. Testing takes place on the movement control channels. If in order to test the disturbance in current, it is necessary to move the electrode, which is located on the border or behind the working zone of movement, then at the output of block 4, depending on the sign of d3, a signal of voltage or voltage is obtained and the voltage level of the furnace transformer is switched. Finally, if the electrode current is small, and the electrode on which the greater voltage drop is at the lower boundary of the displacement zone or below and the gas temperature under the roof is equal to or higher than that set, then the output of logic unit 4 shows a signal H, which includes alarm mode violation. Example. The electrode current is less than a specified value (d3). The voltage drop on the first electrode is greater than on the second (di 0). Both electrodes are in the working zone of movement PH B and e 2 e, the gas temperature under the roof is less than the allowable value 5 QjoiA To eliminate the current deviation at the output of logic unit 4, the signal 01 for lowering the first electrode appears. When the first electrode moves, such a situation may arise when the voltage 1) becomes equal to UQ,

in logical block 4 according to the following laws: i.e. di O and l3. Then, along with signal 01 at the output of unit 4, Vits and signal 92 to move the second electrode down. If the movement of both electrodes down to the lower boundary of the zone of movement Pn does not ensure the elimination of the current deviation, then due to the fact that Pjn at the output of block 4, the signal to move the electrodes 01 and 02 will disappear, and an increase signal will appear tension mon. Q. (ijc, A-. In this case, the process of eliminating the deviation will be similar to the gas temperature under the roof is less than the allowable value QQ j except for the last stage. After the signal to lower the electrodes 01 and 02 disappears at the output of block 4 instead of the monitors, the information signal H which indicates a violation of the technological mode. The electrodes are in the lower position, the electrode current is low, and the temperature under the roof is high. This may be due to a breakage of the electrode or because it is short. In this case, increase. not with Example 2. Electrode current: greater than a given value (d3) Both electrodes are in the working area E, EB 22 PB "H" --I H H The voltage drop on the first electrode is greater than on the second (di 0 The gas temperature under the dome is less than the permissible value (Q for A) At the output of block 4, turn on signal 02 to raise the second electrode. If, when processing Uj, it becomes equal to, then at the output of block 4, turn on the second signal P1 - lifting the first electrode. If the electrodes reach the upper limit of the working area of the displacement (and the current is still more than a predetermined value), the signals P1 and P2 will disappear and the output of block 4 shows the signal CH - switching furnace

transformer to reduce voltage.

And in this case, at the output of unit 4, the signal of CH is received, since the rise of the electrode will further increase the temperature of the gas under the roof.

The economic effect from the introduction of the proposed method will be about 50 thousand rubles. per year one furnace of high unit capacity due to an increase in the productivity of the unit and energy saving.

Claims (3)

1. USSR author's certificate No. 318629, cl. C 21 C 5/52, 1968. 2. USSR author's certificate number 556181, cl. C 21 C 5/52, 1974. 3. Regulation of automatic APP-1. Passport of the OLH 468.129, TsNIIR, Cheboksary, -1977.