JP5343421B2 - Electrode lifting device for steelmaking arc furnace - Google Patents

Description

  The present invention relates to an electrode lifting apparatus for a steelmaking arc furnace that melts scrap by generating arc discharge between an electrode and scrap.

FIG. 3 is a configuration diagram showing an electrode lifting apparatus of a conventional steelmaking arc furnace. A conventional electrode lifting apparatus will be described with reference to FIG.
In the steelmaking arc furnace, the scrap 2 in the furnace body 1 is melted by generating an arc between the scrap 2 in the furnace body 1 and the electrode 3. The raising / lowering operation of the electrode 3 is performed by the electric motor 5. The speed command value output from the comparator 7 is input to the electrode lift control panel 6 via the sensitivity dead zone characteristic generator 13, and the motor 5 is controlled by the electrode lift control panel 6. The sensitivity dead zone characteristic generator 13 is provided to prevent a sensitive reaction related to the raising and lowering of the electrode 3, and a predetermined dead zone is set.

  In addition, as a conventional technique related to an electrode lifting apparatus for a steelmaking arc furnace, adjustment of the dead band width based on the amplitude of the speed feedback signal to the electrode, the integrated value of the rising and falling signals of the speed feedback signal, the number of times of rapid lifting of the electrode There has also been proposed one that performs (see, for example, Patent Document 1).

JP 2003-83680 A

In the conventional electrode lifting apparatus for an arc furnace for steel making as shown in FIG. 3, when the dead zone width is adjusted before the furnace operation, it is generally not performed to adjust the dead zone width again during the operation. . In addition, in order to adjust the dead band width, dedicated software or the like must be used, and the above adjustment has to be performed manually.
Note that the optimum value of the dead zone width varies depending on the condition in the furnace, that is, the initial stage immediately after the start of charging, the subsequent boring period, the melting period, and the refining period. For this reason, conventionally, when the dead zone width deviates from the optimum value, the dead zone characteristics must be adjusted each time, and there is a problem that the efficiency of the furnace operation and the above adjustment cannot be achieved.

  In addition, in the thing of patent document 1, a dead zone width is not necessarily adjusted according to the condition in a furnace, but the said problem was not able to be solved from such description.

  The present invention has been made to solve the above-described problems, and its purpose is to switch the dead zone width to an appropriate value according to the situation in the furnace, and to adjust the furnace operation and dead zone width. It is an object to provide an electrode lifting / lowering device for an arc furnace for steel making that can improve efficiency.

The electrode raising / lowering device for an arc furnace for steel making according to the present invention is an electrode raising / lowering control panel for controlling an electric motor by moving an electrode by generating an arc between the scrap and an electrode for melting the scrap in the furnace body. And a comparator that outputs a speed command value corresponding to the motor so that the actual current and voltage supplied to the electrode become set values, and an electrode lift control based on the speed command value output from the comparator Based on the sensitivity deadband characteristic generator that outputs a command value based on a predetermined deadband characteristic curve or zero to the panel, and the elapsed time after the start of charging the electrode, the sensitivity deadband characteristic generator and a dead zone automatic adjustment circuit for adjusting the dead zone width for outputting zero Te, deadband automatic adjustment circuit, the elapsed time after charging initiation to the electrode, corresponds to the time of expiration of the boring phase If the first set time is less than or equal to the first set time, the dead zone width is set to the first value, and the elapsed time after the start of charging the electrode exceeds the first set time and corresponds to the second time when the dissolution period expires. When the time is equal to or shorter than the set time, the dead zone width is set to a second value smaller than the first value. When the elapsed time after the start of charging the electrode exceeds the second set time, the dead zone width is set to the second value. It is set to a third value smaller than the value .

  According to the present invention, the dead zone width can be switched to an appropriate value according to the situation in the furnace, and the efficiency of the furnace operation and the dead zone adjustment can be improved.

  In order to explain the present invention in more detail, it will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing an electrode lifting apparatus for a steelmaking arc furnace according to Embodiment 1 of the present invention, and FIG. 2 is a diagram for explaining the function of the electrode lifting apparatus for a steelmaking arc furnace according to Embodiment 1 of the present invention. FIG.
1 and FIG. 2, 1 is a furnace body of a steelmaking arc furnace, 2 is a scrap in the furnace body 1, and 3 is an electrode for melting the scrap 2. That is, in the arc furnace for steel making, the scrap 2 is melted by generating an arc between the scrap 2 and the electrode 3. Specifically, the electrode 3 is connected to the secondary side tap of the furnace transformer 4, and an AC power source is connected to the primary side tap. Then, the voltage supplied from the AC power source is stepped down by the furnace transformer 4 and an arc is generated between the scrap 2 and the electrode 3 by applying the secondary voltage between the scrap 2 and the electrode 3. ing.
Reference numeral 5 denotes an electric motor for driving the electrode 3 to move up and down, and 6 denotes an electrode elevating control panel for controlling the electric motor 5 to move the electrode 3 up and down.

  A comparator 7 outputs a speed command value for the electric motor 5 so that the actual current and the actual voltage supplied to the electrode 3 become set values. Specifically, the comparator 7 receives the measured arc current value from the arc current detecting transducer 8 and the measured arc voltage value from the arc voltage detecting transducer 9. Reference numeral 10 denotes a current regulator that outputs an arc current set value to the comparator 7. The comparator 7 compares the input arc current actual measurement value, arc current set value, and arc voltage actual measurement value so that the current-voltage ratio according to the drooping characteristics of the load is constant by constant impedance control. In addition, a speed command value corresponding to the electric motor 5 is output.

  Reference numeral 11 denotes a current transformer built in the in-furnace transformer 4 to which the transducer 8 is connected. Reference numeral 12 denotes an auxiliary transformer provided on the secondary side of the in-furnace transformer 4, and the transducer 9 is connected to the secondary side.

  The speed command value from the comparator 7 is input to a sensitivity dead band characteristic generator 13 that determines the lifting / lowering characteristics of the electrode 3. The sensitivity dead zone characteristic generator 13 is provided to prevent a sensitive reaction related to the raising and lowering of the electrode 3, and a predetermined dead zone is set. The sensitivity dead zone characteristic generator 13 outputs a command value or zero based on a predetermined dead zone characteristic curve to the electrode elevation control panel 6 based on the speed command value from the comparator 7, and the electrode elevation control panel 6. To control the electric motor 5.

  1 is provided with a time count circuit 14 and a dead zone automatic adjustment circuit 15. When the scrap 2 is melted, the time counting circuit 14 counts the elapsed time since the charging of the electrode 3 is started. The dead zone automatic adjustment circuit 15 adjusts the dead zone width for the sensitivity dead zone characteristic generator 13 to output zero to the electrode elevation control panel 6 based on the elapsed time counted by the time counting circuit 14. The dead band width varies greatly depending on the conditions in the furnace, that is, the initial period immediately after the start of charging, the initial to the boring period, the boring period to the melting period, and the elapsed time after the start of charging from the melting period to the refining period. . For this reason, the dead zone automatic adjustment circuit 15 sets the dead zone width according to the elapsed time after the start of charging, and the sensitivity dead zone characteristic generator 13 in order to adjust the dead zone characteristic (dead zone width) in the sensitivity dead zone characteristic generator 13. A dead zone command value is output in response to.

  For example, as shown in FIG. 2, a first set time T1, a second set time T2, and a third set time T3 are preset in the time count circuit 14. Here, the first set time T1 is a time corresponding to the initial expiration, the second set time T2 is a time corresponding to the expiration of the bowling period, and the third set time T3 is a time corresponding to the expiration of the dissolution period. Then, the time count circuit 14 determines which of the count times T corresponds to S1 to S4, and outputs the determination result to the dead zone automatic adjustment circuit 15. The dead zone automatic adjustment circuit 15 selects a dead zone width corresponding to the input signal (elapsed time after the start of charging) based on the input signal from the time count circuit 14, and uses the selected dead zone command value as a dead zone command value. Output to the generator 13. In the dead zone automatic adjustment circuit 15, each dead zone width corresponding to the input signal is set in advance.

FIG. 2 shows an example in which the dead band width in the sensitivity dead band characteristic generator 13 is set as follows by the functions of the time counting circuit 14 and the dead band automatic adjustment circuit 15 as follows.
a. When the elapsed time T from the start of charging is equal to or shorter than the first set time T1 (initial): dead band width 15% (dead band width maintained)
b. When the elapsed time T from the start of charging exceeds the first set time T1 and is equal to or shorter than the second set time T2 (boring period): dead band width 15% (dead band width maintained)
c. When the elapsed time T from the start of charging exceeds the second set time T2 and is less than or equal to the third set time T3 (dissolution period): dead band width 10% (dead band width change)
d. When the elapsed time T from the start of charging exceeds the third set time (refining period): dead band width 5% (dead band width change)

  The dead band ratio shown in FIG. 2 is an example, and is not limited thereto. In addition, in the functions of the time counting circuit 14 and the dead band automatic adjustment circuit 15, an arbitrary value may be set for the dead band width and the time for switching to the dead band width. According to such a configuration, it is possible to apply an optimum dead band width corresponding to various operation patterns. That is, in the example shown in FIG. 2, each value of the dead band width (dead band ratio) in the case of Yes in the first set time T1, the second set time T2, the third set time T3, and S1 to S4 can be arbitrarily changed. It is configured as follows.

According to the first embodiment of the present invention, the dead zone width can be switched to an appropriate value according to the situation in the furnace, and the efficiency of the furnace operation and the dead zone width adjustment can be improved.
That is, the state in the furnace is estimated from the elapsed time after the start of charging, and the optimum dead zone width corresponding to the state is automatically set. For this reason, it is possible to stabilize the furnace operation in the initial period immediately after the start of charging, the initial period to the boring period, the boring period to the melting period, and the melting period to the refining period. Also, by setting in advance the dead band width and the time for switching to the dead band width, it is not necessary to manually adjust the dead band characteristics, and labor can be saved.

It is a block diagram which shows the electrode raising / lowering apparatus of the arc furnace for steel manufacture in Embodiment 1 of this invention. It is a figure for demonstrating the function of the electrode raising / lowering apparatus of the arc furnace for steel making in Embodiment 1 of this invention. It is a block diagram which shows the electrode raising / lowering apparatus of the conventional arc furnace for steel manufacture.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 2 Scrap 3 Electrode 4 Furnace transformer 5 Electric motor 6 Electrode raising / lowering control panel 7 Comparator 8, 9 Transducer 10 Current regulator 11 Current transformer 12 Auxiliary transformer 13 Sensitivity dead zone characteristic generator 14 Time count circuit 15 Dead zone Automatic adjustment circuit

Claims (1)

An electrode for generating an arc between the scrap and the scrap in the furnace body;
An electrode lift control panel for controlling the electric motor to move the electrode up and down;
A comparator that outputs a speed command value corresponding to the electric motor so that an actual current and an actual voltage supplied to the electrode are set values;
A sensitivity dead band characteristic generator that outputs a command value based on a predetermined dead band characteristic curve or zero based on a speed command value output from the comparator,
A dead zone automatic adjustment circuit for adjusting a dead zone width for the sensitivity dead zone characteristic generator to output zero to the electrode elevation control panel based on the elapsed time after the start of charging the electrode;
Equipped with a,
The dead zone automatic adjustment circuit is:
If the elapsed time after the start of charging the electrode is equal to or less than the first set time corresponding to the end of the boring period, the dead zone width is set to the first value,
If the elapsed time after the start of charging the electrode exceeds the first set time and is equal to or less than a second set time corresponding to the end of the dissolution period, the dead band width is set to a second value smaller than the first value. Set the value to
The dead band width is set to a third value smaller than the second value when the elapsed time after the start of charging the electrode exceeds the second set time . Electrode lifting device for arc furnace.

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