JP4199563B2 - Electric melting furnace controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a main electrode, a furnace bottom electrode, and a start electrode in a furnace, and the current is generated on the furnace bottom electrode by a current generated by a high voltage applied between the main electrode and the furnace bottom electrode or between the main electrode and the start electrode. The present invention relates to an electric melting furnace that melts a material to be melted, and more specifically, relates to an electric melting furnace control device that performs operation control on each electrode.
[0002]
[Prior art]
In recent years, melting furnaces for melting incineration ash and dust generated in garbage incineration facilities to make them harmless and generating recyclable slag have been put into practical use. Various types of melting furnaces have been developed and put to practical use. The furnace is equipped with a main electrode (graphite electrode), a furnace bottom electrode, and a start electrode (graphite electrode), and between the main electrode and the furnace bottom electrode or the main electrode. It has only been several years since an electric melting furnace for melting a material to be melted on a furnace bottom electrode by a current generated by a high voltage applied between an electrode and a start electrode has been put into practical use.
[0003]
In the electric melting furnace, a DC voltage is applied between the main electrode and the furnace bottom electrode, a plasma arc is generated to heat the molten slag, and sequentially melted materials such as ash supplied. In addition, since current flows in the slag, Joule heat can be used and efficient melting is performed. Molten ash, etc. becomes slag, is cooled after continuous overflow, and is discharged by a conveyor.
[0004]
The operation of the electric melting furnace is a control voltage value that is set while adjusting the interval between the main electrode and the bottom electrode while adjusting the current value flowing between the main electrode and the bottom electrode during constant operation. The raising / lowering control of the main electrode is performed.
[0005]
However, the material to be melted is a molten slag during steady operation, but the material to be melted is not necessarily in a molten state at the start of operation, and its composition is glassy or metallic, that is, conductive. When there is a mixture of materials and non-conductive materials, and even when they are mixed uniformly, heavy metallic conductive materials are concentrated in the lower layer, and light glassy materials are concentrated in the upper layer. There may be a concentration of non-conductive materials. Therefore, depending on the state of the material to be melted, current flows between the main electrode and the furnace bottom electrode at the start of operation as in the steady operation, and it is possible to shift to the steady operation only by controlling the main electrode. The current does not flow between the main electrode and the furnace bottom electrode, and the starting material is used to gradually melt the material to be melted from the upper layer, and finally the current flows between the main electrode and the furnace bottom electrode. In some cases, it is possible to shift to steady operation, and complicated start-up control is required according to the state of the melt.
[0006]
In addition, since the electrode is made of graphite, it gradually wears out due to the generation of the plasma arc, so it is necessary to perform automatic electrode extension control that automatically adds a new electrode rod to the electrode rod of the shortened electrode. .
[0007]
In addition, regarding the electric melting furnace provided with the main electrode, the furnace bottom electrode, and the start electrode in the furnace, there exist the following patent documents 1-3 by the present applicant.
[0008]
[Patent Document 1]
JP-A-11-237018
[Patent Document 2]
JP 09-156529 A
[Patent Document 3]
JP 09-243267 A
[0009]
[Problems to be solved by the invention]
As described above, the operation of the electric melting furnace requires the control at the start of operation, the control at the steady operation, and the automatic electrode extension control, but the basic structure of the electric melting furnace itself is Even though they are the same, because they have various product specifications depending on the environment used, that is, the garbage incineration facility, etc., each of the above controls has been performed automatically or manually by using a separate and independent control device. There is. In addition, the contents of each control have not been standardized in the electric melting furnaces of many plants. For this reason, it may depend on the experience of a somewhat skilled operator. This is because the electric melting furnace has been put into practical use for only a few years, and so far there has been insufficient field data to unify and integrate the controls. .
[0010]
Here, the inventor of the present application has arrived at the present invention in order to unify and integrate the above-described controls based on past practical experience of electric melting furnaces. The present invention has been made in view of the above-described problems, and an object of the present invention is to solve the above-described problems and enable an electric melting furnace that can be stably operated without being affected by the experience of an operator. It is to provide a control device.
[0011]
[Means for Solving the Problems]
In order to achieve this object, a first characteristic configuration of the electric melting furnace control device according to the present invention includes a main electrode, a furnace bottom electrode, and a start electrode in the furnace, and the main electrode and the furnace bottom electrode are disposed between the main electrode and the furnace bottom electrode. Alternatively, in an electric melting furnace that melts the melt on the furnace bottom electrode by a current generated by a high voltage applied between the main electrode and the start electrode, the main electrode and the start electrode in the furnace Electric melting control that transmits or receives control data to and from the electrode lifting control means for moving the electrode position and the power supply device that applies a voltage between the electrodes, and controls the operation of the electrodes. A furnace control device that performs automatic operation control of the main electrode and the start electrode according to the state of the melted material at the time of start-up, and melts the melted material only by the automatic operation control of the main electrode For driving And a control for moving the electrode position of the main electrode in the furnace to the electrode elevation control means in order to control the voltage applied to the main electrode and the start electrode during steady operation. An electrode raising / lowering control unit that performs the melting, and the activation control unit can melt the state of the melted material to the steady operation by applying a first voltage between the main electrode and the furnace bottom electrode. Automatic operation control of the main electrode Start, and after the control starts, the descent of the main electrode is started, the first current value flowing between the main electrode and the furnace bottom electrode is determined, and the first current value is smaller than a predetermined first threshold value. Performing a lowering control of the main electrode to lower the main electrode to a predetermined lowering position, and performing a control to stop the lowering of the main electrode when the first current value is equal to or greater than the predetermined first threshold value, In automatic operation control of the main electrode, When the first current value is smaller than the predetermined first threshold and the main electrode is lowered to the predetermined lowered position, It is determined that the application of the first voltage cannot change the state of the material to be melted to a molten state capable of shifting to the steady operation. do it, Automatic operation control of the main electrode and the start electrode in which a second voltage application between the main electrode and the start electrode is added to the first voltage application The third current value obtained by starting the descent of the start electrode, determining the second current value flowing between the main electrode and the start electrode, and summing the first current value and the second current value When the value is equal to or greater than a predetermined third threshold value, the start electrode is controlled to stop descending, and the main electrode and the start electrode are kept at the position where the main electrode and the start electrode are stopped. To melt the material to be melted In the point.
[0012]
The current generated by applying a high voltage between the electrodes includes at least one of a plasma arc discharge current and a current flowing through the conductive material of the melt. , Usually both included.
[0013]
According to the first characteristic configuration, the start control unit performs automatic operation control of the main electrode and the start electrode in accordance with the state of the melted object in the start-up control at the time of start-up. It can be used uniformly in various electric melting furnaces that start up using an electrode and a start electrode, and has both a start control unit and an electrode lifting control unit, so that Regardless of the state, the electrode elevation control of the main electrode during the steady operation can be integrated from the start-up control. That is, it is possible to automatically perform the electrode elevation control of the main electrode during the steady operation from the start-up control, or it is possible to perform stable operation that is not affected by the experience of the operator even if the confirmation operation by the operator is interposed.
[0014]
More When the state of the melted material at the time of starting is in a state where a sufficient current cannot flow between the main electrode and the furnace bottom electrode, that is, in a solid state (non-molten state), both the main electrode and the start electrode Energization between both electrodes is performed while the position where the descent stops is substantially in contact with the material to be melted. In general (for example, in ordinary arc welding, etc.), in order to promote melting, and in order to obtain a high voltage when electric power is used, discharge is performed with a constant interval from the melted material. By generating a plasma arc along the surface of the material to be melted while maintaining the position where the main electrode and the start electrode are lowered and stopped, the material to be melted is melted from the surface of the material to be melted inwardly, and efficiently. Relatively high-speed melting is possible, and it is possible to shift to steady operation at an early stage.
[0015]
Same two The start control unit melts the material to be melted by passing a current between the main electrode and the start electrode in a state where the main electrode and the start electrode are stopped at a predetermined descending stop position. After that, when returning the start electrode to a predetermined lift stop position, the start electrode is lifted in a plurality of times with a predetermined stop period in between.
[0016]
Above two According to the characteristic configuration, since the start electrode can be raised while being cooled stepwise, damage to the furnace wall adjacent to the start electrode can be suppressed.
[0017]
Same three The electrode lift control unit includes a PID control unit that performs movement control of the electrode position of the main electrode by PID control, a step control unit that performs step control, and a linear control unit that performs linear control. There is in point.
[0018]
Above three According to the characteristic configuration of the above, by providing a plurality of control units, even if the control unit that is performing the electrode elevation control of the main electrode fails, the other control unit immediately backs up and continues the control It is possible to avoid the shutdown of the electric melting furnace.
[0019]
Same Four The characteristic configuration is that the electrode elevation control unit performs control by the step control unit or the linear control unit immediately after the start of control.
[0020]
Above Four According to the characteristic configuration, the step controller or linear control with good responsiveness to the PID control that requires a relatively long time for the control because the state of the melted material is not stable immediately after the start of control and the fluctuation is large. By using the unit, it is possible to perform more stable control against large fluctuations.
[0021]
Same Five In order to add an electrode rod to the main electrode or the start electrode, at least a conveying means for conveying a spare electrode rod, and the spare electrode rod is automatically joined to the main electrode or the start electrode. Transmission or transmission / reception of control data between the additional electrode automatic extension device and the electrode lifting / lowering control means, the spare electrode rod is taken out from the storage location of the spare electrode rod, and the spare electrode rod Further, an automatic electrode continuation control unit that performs control until automatic addition to the main electrode or the start electrode is further provided.
[0022]
Above Five According to the characteristic configuration of the above, the same electric melting furnace control device includes an electrode automatic extension control unit, so that the startup control by the startup control unit and the elevation control of the main electrode during steady operation by the electrode elevation control unit, In addition, the automatic control of the automatic addition of the electrodes by the automatic automatic addition control unit can be easily performed in a unified manner in which the conventional electric melting furnaces are individually linked to each other. Become.
[0023]
Same Six The characteristic configuration is that after the automatic electrode joining by the automatic electrode joining control unit is completed, the start-up control by the activation control unit is automatically started.
[0024]
Above Six According to the characteristic configuration, it is possible to automatically restart the operation of the electric melting furnace stopped during the automatic electrode extension.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an electric melting furnace control apparatus according to the present invention (hereinafter referred to as “the present invention apparatus” as appropriate) will be described with reference to the drawings.
[0026]
First, as shown in FIG. 2, the electric melting furnace 30 which is a control target of the apparatus 1 of the present invention is provided with a main electrode 31 and a start electrode 33 which are inserted into the furnace 36 through the furnace wall ceiling 35a. Each of the electrodes is supported by an electrode lifting device 23a for the main electrode 31 and an electrode lifting device 23b for the start electrode 33, and the tip position of each electrode in the furnace 36 can be moved up and down. A furnace bottom electrode 32 is provided on the furnace bottom 35 b and is connected to the current collector plate 34. Moreover, the furnace side wall part 35c is provided with a supply port 37 of ash which is a material to be melted, and the material to be melted is supplied into the furnace 36 by a conveying means such as a screw conveyor. The main electrode 31 is connected to the negative electrode of the DC power supply 22 a that generates a high voltage via a support arm that supports the main electrode 31. The start electrode 33 is connected to one positive electrode of the DC power supply device 22a through a support arm that supports the start electrode 33. The furnace bottom electrode 32 is connected to the other positive electrode of the DC power supply device 22a through a current collector plate. The DC power supply 22a is supplied with an extra high voltage via a VCB (vacuum circuit breaker) 22b provided in the high voltage switchboard.
[0027]
In the electric melting furnace 30 configured as described above, a DC high voltage is applied between the main electrode 31 and the furnace bottom electrode 32 to generate a plasma arc to heat the molten slag 40 on the furnace bottom electrode 32 and sequentially supply it. Melt the material to be melted such as ash. In addition, since current flows in the slag, Joule heat can be used and efficient melting is performed. Molten ash or the like becomes slag, is cooled after continuous overflowing from the outlet 38 provided in the furnace side wall 35c, and is discharged by the conveyor.
[0028]
As shown in FIG. 1, the device 1 of the present invention includes a control calculation processing unit 2, a control calculation processing unit 2, an electrode lifting device 23 a of an electric melting furnace 30, an electrode lifting device control panel 23 of a 23 b, a DC power supply device 22 a. The I / O interface 3 for transferring control input / output data to / from the VCB 22b and the like, and the display 4 for displaying various data are configured as one control panel. Three control functions of the start-up control of the furnace 30, the main electrode lifting / lowering control during steady operation, and the automatic electrode extension control are exhibited.
[0029]
The control arithmetic processing unit 2 includes a central arithmetic processing unit 5 configured by a general-purpose computer and a PID control unit 12 configured by a dedicated controller. The central arithmetic processing unit 5 further includes an activation control unit that exclusively performs the startup control. 6, an electrode lifting / lowering control unit 7 exclusively performing main electrode lifting / lowering control during the steady operation, an electrode automatic anchoring control unit 8 exclusively performing the electrode automatic anchoring control, and a distributed control system used for control monitoring ( A DCS interface 9 is provided to exchange input / output data via a DCS) 20 and a data link 21 which is a kind of computer network. The PID control unit 12 implements a PID control function for executing the electrode lifting control of the electrode lifting control unit 7 by PID control with a dedicated controller, and forms part of the electrode lifting control unit 7. The activation control unit 6 of the central processing unit 5, the electrode lifting / lowering control unit 7 excluding the PID control unit 12, and the electrode automatic continuation control unit 8 are executed by a general-purpose computer constituting the central processing unit 5. Is realized by software processing. Furthermore, the electrode elevation control unit 7 in the central processing unit 5 includes a step control unit 10 that performs the electrode elevation control of the electrode elevation control unit 7 by step control by software processing, and the electrode elevation control of the electrode elevation control unit 7. In addition to the linear control unit 11 that is executed by linear control by software processing, it is possible to manage which of the step control unit 10, the linear control unit 11, and the PID control unit 12 performs electrode elevation control, and between each control unit The management when the control is taken over is also performed.
[0030]
The I / O interface 3 directly controls the electrode lifting device control panel 23, the DC power supply device 22a, the VCB 22b, the electrode automatic footing device control panel 24 for directly controlling the electrode automatic footing device 24a, and the electrode mounting device 25a. Input / output data for control is input / output to / from the electrode mounting device control panel 25 via individual communication lines or data links.
[0031]
In the present embodiment, in the automatic electrode extension control, the input / output data for control with the furnace top crane 26 that transports the new electrode (preliminary electrode rod) from the electrode mounting device 25a to above the old electrode currently in use. The transfer is performed via the DCS 20.
[0032]
Next, the processing procedure of the startup control of the electric melting furnace 30 by the activation control unit 6 of the apparatus 1 of the present invention will be described with reference to the flowcharts of FIGS. In the following description, each process is executed by the activation control unit 6 unless otherwise specified.
[0033]
When the start command (# 0) by the operator is received from the DCS 20, confirmation of each device state (presence / absence of alarm, etc.), pre-processing such as alarm display and time delay processing by the timing timer are performed (# 1), A VCB input command is output to the VCB 22b (# 2). The VCB 22b is turned on by a VCB input command, and an extra high voltage is supplied to the DC power supply device 22a. Subsequently, after receiving the VCB on state input of the DCS 20, a main electrode lowering command is output to the electrode lifting device control panel 23 (# 3). The electrode lifting device control panel 23 starts the lowering control on the electrode lifting device 23a for the main electrode 31 in response to the main electrode lowering command. As the main electrode 31 descends, the first current value I flowing between the main electrode 31 and the furnace bottom electrode 32 according to the state of the material to be melted. ₁ In order to detect the change of the first current value I from the DC power supply 22a. ₁ (Data) is received (# 4), and the first current value I ₁ Is a predetermined first threshold I _1A It is determined whether it is above (# 5: initial current over determination). First current value I ₁ Is the first threshold I _1A If smaller, the main electrode wire slack data is received from the electrode lifting device control panel 23 (# 6), and the presence or absence of main electrode wire slack is determined (# 7). If there is no wire slack according to the main electrode wire slack determination, it is determined that the lower end of the main electrode 31 has not been lowered downward, and the process returns to steps # 4 and # 5. Here, if there is a loose wire in the determination of step # 7, the main electrode 31 has been lowered to the lower side and cannot be further lowered, and the first current value I ₁ Is the first threshold I _1A Since it is smaller, it is determined that the material to be melted is in a solid (non-molten) state, and the process proceeds to the second pattern start-up control (steps # 20 to # 46) using the start electrode 33 described later.
[0034]
In the initial current over determination in step # 5, the first current value I ₁ Is the first threshold I _1A In the above case, since the melted material is in a conductive state (melted state) to some extent, the start-up control is completed without using the start electrode 33 by simply applying a DC voltage between the main electrode 31 and the furnace bottom electrode 32. it can. (First pattern startup control)
[0035]
In the start-up control of the first pattern, the first current value I ₁ Is the first threshold I _1A If it becomes above, in order to stop the fall of the main electrode 31, the main electrode fall stop command will be output with respect to the electrode raising / lowering device control board 23 (# 8). The electrode lifting device control panel 23 causes the electrode lifting device 23a to stop the lowering of the main electrode 31 in response to a main electrode lowering stop command. Subsequently, time delay processing by the main arc starting timer is performed (# 9), and the first current value I ₁ Is the first threshold I _1A Greater second threshold I _1B Until the above is reached, the DC voltage application between the main electrode 31 and the furnace bottom electrode 32 is continued at the lowering stop position of the main electrode 31 (# 10 to # 12). Specifically, the first current value I from the DC power supply 22a. ₁ (Data) is received (# 10), and the first current value I ₁ Is the second threshold I _1B It is determined whether or not (# 11: second initial current over determination), the first current value I ₁ Is the second threshold I _1B Steps # 10 and # 11 are repeated until the above is reached, and a time delay process using an initial current overtimer is performed in parallel (# 12). The second initial current over determination (# 10, # 11) is also performed during the time delay process, and the first current value I ₁ Is the second threshold I _1B Make sure that this is the case.
[0036]
First current value I ₁ Is the second threshold I _1B After the time delay processing by the initial current overtime is completed, the voltage V between the main electrode 31 and the furnace bottom electrode 32 is reached. ₁ In order to raise the lower end position of the main electrode 31 so that the voltage value is appropriate for starting steady operation, a main electrode raising command is output to the electrode lifting device control panel 23 (# 13). The electrode lifting device control panel 23 starts raising control of the main electrode 31 with respect to the electrode lifting device 23a in response to a main electrode raising command.
[0037]
Voltage value V between main electrode 31 and furnace bottom electrode 32 ₁ (Data) is received from the DC power supply 22a (# 14), and the voltage value V ₁ Is a predetermined first threshold voltage V _1A It is determined whether or not (# 15), V ₁ Is V _1A Steps # 14 and # 15 are repeated until V ₁ Is V _1A If it becomes above, a main electrode raise stop command will be output with respect to the electrode raising / lowering apparatus control board 23 (# 16). First current value I ₁ Shifts to a steady operation through a predetermined post-process (# 17) such as confirmation of whether or not the current is greater than or equal to a predetermined current value and setting of conditions at the start of steady operation.
[0038]
Next, the startup control of the second pattern will be described. If it is determined in step # 7 that there is a loose wire, a time delay process is performed by a start electrode activation timer (# 20), and an electrode lifting device is provided on condition that the operator has selected to use the start electrode in DCS20 A start electrode lowering command is output to the control panel 23 (# 21). The electrode lifting device control panel 23 starts the lowering control for the electrode lifting device 23b for the start electrode 33 in response to the start electrode lowering command. The second current value I flowing between the main electrode 31 and the start electrode 33 corresponding to the state of the melt as the start electrode 33 descends and approaches the surface of the melt. ₂ In order to detect the change of the first current value I from the DC power supply 22a. ₁ And the second current value I ₂ The third current value I that is the sum of ₃ (Data) is received (# 22), and the third current value I ₃ Is a predetermined third threshold I _3A It is determined whether it is above (# 23: third initial current over determination). Third current value I ₁ Is the third threshold I _3A If it is smaller, start electrode wire slack data is received from the electrode elevator control panel 23 (# 24), and the presence or absence of start electrode wire slack is determined (# 25). If there is no wire slack according to the start electrode wire slack determination, it is determined that the lower end of the start electrode 33 has not been lowered to the bottom, and the process returns to steps # 22 and # 23.
[0039]
Here, the third current value I ₃ Is the third threshold I _3A If it is smaller and there is loose wire, the non-conductive substance is concentrated near the surface of the melt and is in a solid state (non-molten state). An alarm is generated for the DCS 20 in order to perform a process of supplying a conductive material to the DCS 20.
[0040]
In the third initial current over determination in step # 23, the third current value I ₃ Is a predetermined third threshold I _3A In the above case, it is determined that the melt can be melted by generating a plasma arc along the surface of the melt between the main electrode 31 and the start electrode 33 at the descending position of the start electrode 33, and the start electrode In order to stop the descent of the electrode, a start electrode descent stop command is output to the electrode elevator control panel 23 (# 26). The electrode lifting / lowering device control panel 23 stops the lowering of the electrode lifting / lowering device 23b by a start electrode lowering / stopping command. The main electrode 31 and the start electrode 33 continue to generate a plasma arc between the two electrodes along the surface of the melt while maintaining the stop positions of the respective electrodes, and heat generated downward by the plasma arc and the plasma arc. The material to be melted is gradually melted from the surface by conduction (# 27 to # 30). Specifically, in the state where a high voltage is applied between the main electrode 31 and the start electrode 33, a time delay process by a timing timer is performed (# 27), and the first current value I is supplied from the DC power supply device 22a. ₁ (Data) is received (# 28), and the first current value I ₁ Is the second threshold I _1B It is determined whether or not (# 29: second initial current over determination), and the first current value I ₁ Is the second threshold I _1B Steps # 28 and # 29 are repeated until the above is reached, and a time delay process using an initial current overtimer is performed in parallel (# 30). The second initial current over determination (# 28, # 29) is also performed during the time delay process (# 30), and the first current value I ₁ Is the second threshold I _1B Make sure that this is the case. As a result, the material to be melted is in a state where it can sufficiently shift to the steady operation, and therefore, an end step (# 31 to # 46) is entered in order to end the start-up control of the second pattern.
[0041]
First current value I ₁ Is the second threshold I _1B After the time delay processing by the initial current overtime is completed as described above, first, a VCB cut command is output to the VCB 22b (# 31). The VCB 22b is turned off by the VCB cut command, the extra high voltage supply to the DC power supply 22a is cut off, and the high voltage is applied between the main electrode 31 and the furnace bottom electrode 32 and between the main electrode 31 and the start electrode 33. Canceled.
[0042]
Next, the main electrode supporting arm position data is received from the electrode lifting device control panel 23 (# 32), the main electrode supporting arm position is stored (# 33), and the main electrode lifting command is sent to the electrode lifting device control panel 23. Is output (# 34). The electrode lift device control panel 23 starts the lift control for the electrode lift device 23a for the main electrode 31 in response to the main electrode lift command.
[0043]
While the main electrode 31 is being raised, main electrode support arm position data is received from the electrode lifting device control panel 23 (# 35), and the main electrode support arm position stored in step # 33 and the current main electrode support arm position are used to determine the increase distance. While making the determination (# 36), the predetermined distance is increased. After determining that the main electrode 31 has moved up the predetermined distance, a main electrode ascent / stop command is output to the electrode lifting device control panel 23 (# 37). The electrode lifting device control panel 23 causes the electrode lifting device 23a to stop the lifting of the main electrode 31 in response to a main electrode lifting stop command.
[0044]
Subsequently, step-up control (# 38 to # 46) of the start electrode is executed. Specifically, a start electrode raising command is output to the electrode lifting device control panel 23 (# 38). The electrode lift device control panel 23 starts the lift control for the electrode lift device 23b for the start electrode 33 in response to the start electrode lift command. Time delay processing by the timing timer is performed (# 39), and a start electrode ascent / stop command is output to the electrode lifting device control panel 23 (# 40). The electrode lift device control panel 23 stops the lift of the electrode lift device 23b in response to a start electrode lift stop command. Further, time delay processing by the timing timer is performed again (# 41), and a start electrode raising command is output to the electrode lifting device control panel 23 (# 42). The electrode lift device control panel 23 again starts the lift control for the electrode lift device 23b for the start electrode 33 in response to the start electrode lift command. A time delay process is performed again by the timing timer (# 43), and a start electrode ascent / stop command is again output to the electrode elevator control panel 23 (# 44). The electrode lift device control panel 23 stops the lift of the electrode lift device 23b in response to a start electrode lift stop command. When start electrode support arm position data is received from the electrode lifting device control panel 23 (# 45), it is determined whether the start electrode support arm position is equal to or higher than a predetermined height (# 46), and the predetermined height is not reached Repeats the processing of steps # 38 to # 46 until the predetermined height is reached, and ends the start-up control of the second pattern.
[0045]
Next, the electrode raising / lowering control of the main electrode 31 by the electrode raising / lowering control part 7 of this invention apparatus 1 is demonstrated.
[0046]
The electrode elevating control unit 7 outputs various control commands to the electrode elevating device control panel 23 using any one of the step control unit 10, the linear control unit 11, and the PID control unit 12, and the main electrode Elevating control is performed on the electrode lifting device 23a for 31. A first current value I flowing between the main electrode 31 and the furnace bottom electrode 32 with respect to the DC power supply device 22a. ₁ By adjusting the distance between the main electrode 31 and the furnace bottom electrode 32 by controlling the elevation of the main electrode 31 while controlling the constant current so that becomes constant current, the plasma voltage (V ₁ ) Is controlled.
[0047]
1st electric current value I with respect to the electrode raising / lowering control part 7 ₁ And voltage value V ₁ Each set value is input from the DCS 20. In addition, when the current / voltage set values are changed from the DCS 20, the actual set values are gradually changed by the change rate setting. Note that the change rate setting is switched for each control mode of electrode elevation control. The control mode includes a step control mode by the step control unit 10, a linear control mode by the linear control unit 11, a PID control mode by the PID control unit 12, and a manual control mode by manual mode. An increase rate and a decrease rate with respect to the voltage set value and the current set value are preset and tabulated.
[0048]
Next, an outline of electrode elevation control in the PID control mode by the PID control unit 12 will be described. The PID controller 12 receives the voltage V received from the DC power supply 22a. ₁ Based on the voltage setting value, the calculation process is performed according to the processing procedure shown in FIG.
[0049]
First, voltage V ₁ The deviation DV of the voltage setting value is obtained, and a gap calculation for outputting the deviation DV ′ is performed on the deviation DV based on the gap calculation characteristics shown in FIG. 7, and then the reverse operation for compensating the deviation DV ′ is performed. The PID calculation for attracting is executed and the main electrode lifting speed is output. The PID output is subjected to an output limiter process, and the main electrode lifting speed is output within a predetermined output upper limit value and output lower limit value. Note that the gap width GW of the gap calculation, the proportional, integral, and differential setting values of the PID calculation, and the output upper limit value and output lower limit value of the output limiter process are set as setting values, respectively.
[0050]
Further, when shifting from another control mode to the PID control mode, the operation starts from the output before the transition. On the other hand, when the PID control unit 12 fails during PID control, it automatically shifts to a control mode (step control mode or linear control mode) set in advance in the control mode at the time of PID control failure.
[0051]
Next, an outline of the electrode lifting control in the step control mode by the step controller 10 will be described. The step controller 10 receives the voltage V received from the DC power supply 22a. ₁ Based on the voltage setting value, the arithmetic processing is performed according to the processing procedure shown in FIG.
[0052]
First, voltage V ₁ And a deviation DV of the voltage setting value are determined, it is determined which of the six regions shown in FIG. 8 corresponds to the deviation DV, and five types of electrode elevation control are executed on the electrode elevation device control panel 23. . That is, four deviation determination thresholds ΔV1, ΔV2, −ΔV1, and −ΔV2 are set (where ΔV2> ΔV1), and the first descending operation is performed when DV ≧ ΔV2, and when ΔV2> DV ≧ ΔV1. The second descending operation is executed when DV ≦ −ΔV2, the first ascending operation is performed when −ΔV2 <DV ≦ −ΔV1, and any ascending / descending operation is performed when −ΔV1 <DV <ΔV1. Also do not run.
[0053]
The first descent operation and the first ascending operation, and the second descent operation and the second ascending operation are the same in the set values of the operation time and the stop time during each control, except that the moving directions of the electrodes are opposite to each other. On the other hand, the first descent operation and the second descent operation, and the first ascending operation and the second ascending operation have the same moving direction of the electrodes, but the set values of the operation time and stop time during each control are different. Each first operation is set so as to perform a greater descent or rise.
[0054]
Therefore, the step control unit 10 determines the operation time and stop time of each operation when any of the first descending operation, the second descending operation, the first ascending operation, or the second ascending operation is selected as described above. Based on the set value, an electrode lowering command and an electrode lowering stop command, or an electrode raising command and an electrode raising stop command are output to the electrode lifting device 23a for the main electrode 31. If no operation is selected, no elevation control command is output.
[0055]
Next, an outline of electrode elevation control in the linear control mode by the linear control unit 11 will be described. The linear controller 11 receives the voltage V received from the DC power supply 22a. ₁ Based on the voltage setting value, the arithmetic processing is performed according to the processing procedure shown in FIG.
[0056]
First, voltage V ₁ The deviation DV of the voltage setting value is obtained, and a gap calculation for outputting the deviation DV ′ is performed on the deviation DV based on the gap calculation characteristics shown in FIG. 7, and then the reverse operation for compensating the deviation DV ′ is performed. The ratio calculation (see the ratio calculation formula in Formula 1) is executed, and the main electrode lifting speed R is output.
[0057]
[Expression 1]
R = GA · DV '+ BI
[0058]
The ratio calculation output R is subjected to an output limiter process, and the main electrode lifting speed is output within a predetermined output upper limit value and output lower limit value. Here, the gap width GW of the gap calculation, the gain GA and bias BI of the ratio calculation formula, and the output upper limit value and the output lower limit value of the output limiter process are set as set values, respectively. The gap width GW for the gap calculation may be either the same setting as in the PID control mode or a different setting.
[0059]
The electrode lift control unit 7 selects a preset step control mode or linear control mode at the start of electrode lift control of the main electrode 31, and activates the corresponding step control unit 10 and linear control unit 11, It is also preferable to shift from the control mode being executed to the PID control mode when the voltage fluctuation becomes stable.
[0060]
Next, the outline of the processing procedure in the automatic electrode extension control of the main electrode 31 by the automatic electrode extension control unit 8 of the device 1 of the present invention will be described with reference to the flowchart of FIG. In the present embodiment, for the plurality of electric melting furnaces 30, the automatic electrode continuation device 24 a and the automatic electrode continuation device control panel 24, the electrode gantry device 25 a and the electrode gantry device control necessary for automatic electrode continuation are provided. The automatic electrode extension control when the panel 25 and the furnace top crane 26 are shared will be described. However, in the present embodiment, the device 1 of the present invention is provided for each electric melting furnace 30 and the electric automatic melting control unit 8 (hereinafter referred to as “own furnace” as appropriate) is also controlled. Electrode automatic extension control is executed. In the following description, unless otherwise specified, each process in each process is executed by the electrode automatic continuation control unit 8.
[0061]
First, the step for preparing the stern (# 100) will be described. The main electrode lifting / lowering device position data is received from the electrode lifting / lowering device control panel 23, and it is determined whether or not the main electrode 31 of the own furnace is capable of automatic electrode extension, and if so, a message to that effect is sent to the DCS 20. Output. Upon receiving the start-up preparation start command from the DCS 20 by the operator, a selection command indicating that the automatic top-up control has been selected is output to the top crane 26 for which the own furnace is to be operated. Each state data for confirming the presence / absence of abnormality is acquired from each device 23 to 26, and further, the start electrode support arm position data is received from the electrode lifting device control panel 23, and it is determined whether or not the automatic electrode extension operation is possible. . If there is no abnormality in any of them, a preparation preparation command is output to the electrode automatic extension device control panel 24 and the furnace top crane 26. The automatic electrode extension device control panel 24 and the furnace top crane 26 execute a predetermined preparation operation when receiving a preparation preparation command, respectively, and output a message to that effect to the automatic electrode addition control unit 8. When the completion data for the prepping operation is received from both the automatic electrode continuation device control panel 24 and the furnace top crane 26, a message to that effect is output to the DCS 20.
[0062]
Next, the automatic extension process (# 110) will be described. On the basis of the DCS 20 prepping operation completion message, the operator issues an automatic continuation start command on the DCS 20 and, upon receiving the command from the DCS 20, sends an automatic continuation start command to each related device. In the automatic extension process (# 110), first, an electrode dispensing process (# 111) is executed.
[0063]
In the electrode dispensing process (# 111), when the electrode mounting device control panel 25 receives the automatic extension start command, the electrode mounting device 25a performs a predetermined electrode dispensing operation so that a new electrode can be taken out. When the electrode take-out possible data is received from the electrode mounting device control panel 25, a new electrode preparation command is transmitted to the electrode automatic extension device control panel 24.
[0064]
Subsequent to the electrode dispensing process (# 111), the ash supply stopping process (# 112) and the new electrode gripping process (# 113) for stopping the ash supply operation during the ash supply operation are executed in parallel. In the new electrode gripping step (# 113), when the automatic electrode extension device control panel 24 receives the new electrode preparation command, the automatic electrode extension device 24a performs an operation of holding the new electrode. In this operation, at the same time, a male screw joining member that is screwed into the female screw portion at the upper end portion of the old electrode is attached to the female screw portion at the tip portion (lower end portion) of the new electrode.
[0065]
Subsequent to the new electrode gripping step (# 113), in the crane intermediate point movement step (# 114), a crane intermediate point movement command is output to the furnace top crane 26, and the furnace top crane 26 receives the command, and the crane is moved. Move to the middle point.
[0066]
Subsequently, an electrode operation stop process (# 115) is performed. More specifically, after the furnace top crane 26 has moved to the middle point and confirmed that the ash supply operation has stopped, the VCB 22b is in an on state, that is, an extra high voltage is supplied to the DC power supply device 22a, and between the electrodes. When a high voltage is applied, a command to stop the automatic electrode lifting operation and turn off the VCB 22b is output to the electrode lifting device control panel 23. After the application of the high voltage to the main electrode 31 and the lifting control are canceled, after a lapse of a predetermined time, an electrode standby position lifting command is output to the electrode lifting device control panel 23, and the electrode lifting device control panel 23 outputs the command. The main electrode 31 is raised or lowered to a predetermined standby position.
[0067]
If the electrode lifting / lowering control unit 7 is performing electrode lifting / lowering control of the main electrode 31 on the electrode lifting / lowering device control panel 23, the DC power supply device 22a, and the VCB 22b at the start of the electrode operation stopping step (# 115), the electrode automatic The control of the joint control unit 8 is executed in preference to the electrode lifting control of the electrode lifting control unit 7, and the electrode lifting control by the electrode lifting control unit 7 is interrupted.
[0068]
Following the electrode operation stopping step (# 115), in the crane joint point moving step (# 116), first, an instruction to open the handrail passage gate, which becomes an obstacle to the movement of the furnace top crane 26, is output to the DCS 20, Handrail passage gate open state data is received from the DCS 20 and a crane joint point movement command is output to the top crane 26. The furnace top crane 26 receives the command and moves the crane to the anchor point. Subsequently, an N2 detachment device opening command is output to the electrode lifting device control panel 23, and confirmation data for opening the N2 detaching device of the electrode lifting device 23a is received from the electrode lifting device control panel 23.
[0069]
Next, after the furnace top crane 26 has moved to the anchor point, an automatic electrode anchoring device cover lowering command is output to the electrode automatic anchoring device control panel 24 in the electrode automatic anchoring device cover lowering step (# 117). Then, the electrode automatic extension device 24a executes the cover lowering process.
[0070]
Subsequently, in the crane joint point moving step (# 116), confirmation data for opening the N2 detaching device of the electrode lifting device 23a is received from the electrode lifting device control panel 23, and in the crane unwinding / main electrode lifting step (# 118), After the cover lowering process by the electrode automatic extension device 24a is completed, a crane lowering command is output to the furnace top crane 26, and the furnace top crane 26 starts the lowering operation. After confirming whether the landing height has been reached from the furnace top crane 26 or whether the crane has been completely unwound, a main electrode raising command is output to the electrode lifting device control panel 23. The electrode elevating device 23a starts ascending the main electrode 31, and receives the old electrode upper end position detection data from the electrode automatic extension device control panel 24, and based on the position detection data, the electrode elevating device control panel 23 An electrode ascent / stop command is output, and the main electrode 31 stops ascending.
[0071]
Subsequently, in the electrode joining step (# 119), an electrode joining command is output to the electrode lifting device control panel 23, and the electrode lifting device control panel 23 is used to join the new electrode to the old electrode according to the command. Perform the action. After the completion of the transfer operation, a notification of completion to that effect is received, and a transfer operation end message is output to the DCS 20.
[0072]
Subsequently, an electrode holding / replacement step (# 120) is performed. At the end of the electrode extension step (# 119), the old electrode is supported by the electrode support arm of the electrode lifting device 23a, and the new electrode is supported by the electrode automatic extension device 24a. Therefore, in a state where the new electrode is supported by the electrode automatic extension device 24a, an electrode gripping change command is output to the electrode lifting device control panel 23, and the electrode lifting device 23a changes the support position from the old electrode to the new electrode. Moving. When the electrode replacement is completed, a new electrode release command is output to the electrode automatic extension device control panel 24, and the support of the new electrode is released to the electrode automatic extension device 24a.
[0073]
When the automatic electrode extension device 24a finishes the new electrode releasing operation, the crane retracting step (# 121) is executed, and the furnace top crane 26 executes the crane hoisting operation, the intermediate point moving operation, and the like. Subsequently, in the post-processing step (# 122), a command to close the handrail passage date is output to the DCS 20, and the handrail passage gate closed state data is received from the DCS 20, and the N2 detachment device mounting command is sent to the electrode lifting device control panel 23. Is received from the electrode lifting / lowering device control panel 23 to confirm that the electrode lifting / lowering device 23a is attached to the N2 desorption device.
[0074]
When the completion of the post-processing step (# 122) is confirmed, the electrode automatic extension control unit 8 instructs the start-up control unit 6 to start up the electric melting furnace 30 (# 123). After the start-up control by the start control unit 6 is finished, when the operation shifts to the steady operation by the electrode lifting control unit 7, an ash supply operation start command is output to the ash supply device (# 124). When confirmation data indicating that the ash supply operation is being performed from the ash supply device is received and the completion of the retreat operation of the furnace top crane 26 in the crane retreat process (# 121) is confirmed, in the end process (# 125), to the DCS 20 , An automatic continuation completion message is output, an automatic continuation completion confirmation command is received from the DSC 20, an automatic continuation control completion instruction is output to the furnace crane 26, and the automatic electrode continuation of the main electrode 31 is performed. End foot control.
[0075]
As described above, the device 1 of the present invention includes the activation control unit 6, the electrode lifting / lowering control unit 7, and the electrode automatic continuation control unit 8, so that in the automatic electrode continuation control of the main electrode 31, The automatic start-up control of the main melting furnace 30 and the automatic raising / lowering control of the main electrode 31 during steady operation can be automatically executed smoothly, and the automatic electrode extension control of the main electrode 31 can be terminated.
[0076]
Hereinafter, another embodiment will be described.
In the above embodiment, the apparatus 1 of the present invention has been described on the premise that the apparatus 1 is provided for each electric melting furnace 30. However, one apparatus 1 of the present invention simultaneously connects a plurality of electric melting furnaces 30. The form to control may be sufficient.
[0077]
The specific operation / processing procedure and configuration of each of the activation control unit 6, the electrode lifting / lowering control unit 7, and the electrode automatic continuation control unit 8 of the device 1 of the present invention are the same as the operation / processing procedure of the above embodiment. It is not limited to the configuration, and can be appropriately changed within the technical scope of the present invention.
[0078]
For example, the PID control unit 12 of the electrode elevation control unit 7 may be realized by software processing in the same manner as the step control unit 10 and the linear control unit 11 without configuring with a dedicated controller. Furthermore, the automatic electrode joining control by the electrode automatic joining control unit 8 may be executed for the start electrode 33.
[0079]
【The invention's effect】
As described above, according to the present invention, stable start-up control of an electric melting furnace that is not affected by the experience of an operator, automatic elevating control of the main electrode during steady operation, and automatic electrode extension control of the main electrode are possible. Become.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an electric melting furnace control device according to the present invention.
FIG. 2 is a conceptual diagram of a configuration of an electric melting furnace to be controlled by the electric melting furnace control apparatus according to the present invention.
FIG. 3 is a flowchart showing a processing procedure for startup control of an electric melting furnace.
FIG. 4 is a flowchart showing a processing procedure for startup control of an electric melting furnace.
FIG. 5 is a flowchart showing a processing procedure for startup control of an electric melting furnace.
FIG. 6 is a process diagram for explaining the processing procedure of PID control by the PID control unit.
FIG. 7 is a diagram showing input / output characteristics used for gap calculation.
FIG. 8 is an explanatory diagram for explaining a processing procedure of step control by a step control unit;
FIG. 9 is a process diagram for explaining a linear control processing procedure by a linear control unit;
FIG. 10 is a flowchart showing a processing procedure for automatic electrode extension control.
[Explanation of symbols]
1: Electric melting furnace control device according to the present invention
2: Control processing unit
3: I / O interface
4: Display
5: Central processing unit
6: Start control unit
7: Electrode lifting control unit
8: Automatic electrode extension control unit
9: DCS interface
10: Step controller
11: Linear controller
12: PID controller
20: Distributed control system (DCS)
21: Data link
22a: DC power supply device
22b: VCB (vacuum circuit breaker)
23: Electrode lifting device control panel
23a: Electrode lifting device for main electrode
23b: Electrode lifting device for start electrode
24: Electrode automatic extension device control panel
24a: Automatic electrode extension device
25: Electrode mounting device control panel
25a: Electrode mounting device
26: Furnace top crane
30: Electric melting furnace
31: Main electrode
32: Furnace bottom electrode
33: Start electrode
34: Current collector
35a: furnace wall ceiling
35b: Furnace bottom
35c: furnace side wall
36: Inside the furnace
37: Ash supply port
38: Outlet
40: Molten slag

Claims (6)

A furnace is provided with a main electrode, a furnace bottom electrode, and a start electrode, and a current generated by a high voltage applied between the main electrode and the furnace bottom electrode or between the main electrode and the start electrode is provided on the furnace bottom electrode. In the electric melting furnace for melting the melted material in
Transmission or transmission / reception of control data between the main electrode and the electrode elevation control means for moving the electrode position in the furnace of the start electrode, and the power supply device that applies a voltage between the electrodes, An electric melting furnace control device that performs operation control on each of the electrodes,
Start-up control that performs automatic operation control of the main electrode and the start electrode according to the state of the material to be melted at start-up, and starts up to a steady operation in which the material to be melted is melted only by the automatic operation control of the main electrode. And
Electrode lifting control for controlling the movement of the position of the main electrode in the furnace to the electrode lifting control means in order to control the voltage applied between the main electrode and the furnace bottom electrode during steady operation. And comprising
The activation control unit, the first voltage application between the bottom electrode and the main electrode, starts the automatic operation control of the main electrode to the state of the object to be melt in a molten state can be migrated to the steady operation And starting the descent of the main electrode after the start of control, determining a first current value flowing between the main electrode and the furnace bottom electrode, and when the first current value is smaller than a predetermined first threshold, Performing a lowering control of the main electrode to lower the main electrode to a predetermined lowering position, and performing a control to stop the lowering of the main electrode when the first current value is equal to or greater than the predetermined first threshold value;
In the automatic operation control of the main electrode, when the first current value is smaller than the predetermined first threshold and the main electrode is lowered to the predetermined lowered position, the first voltage application is wherein it is determined that it is not possible to allow a molten state transition the state of the melt in the steady operation, the second voltage application between the main electrode and the start electrode to said first voltage application The operation shifts to the automatic operation control of the added main electrode and the start electrode , starts the descent of the start electrode, determines a second current value flowing between the main electrode and the start electrode, and determines the first current value When the third current value obtained by adding the second current value exceeds a predetermined third threshold value, the start electrode is controlled to stop descending, and the main electrode and the start electrode are stopped descending. Place Remains in said main electrode to melt the object to be melt by applying a current between said start electrode electric melting furnace control device comprising a. The start control unit is configured to melt the material to be melted by flowing a current between the main electrode and the start electrode in a state where the main electrode and the start electrode are stopped at a predetermined lowering stop position. when returning the electrodes to a predetermined elevated stop position, the rise of the start electrode, an electric melting furnace according to claim 1, characterized in that to perform a plurality of times while sandwiching the predetermined stop period during Control device. The electrode elevation control unit includes a PID control unit that performs movement control of the electrode position of the main electrode by PID control, a step control unit that performs step control, and a linear control unit that performs linear control. The electric melting furnace control device according to claim 1 or 2 . The electric melting furnace control device according to claim 3 , wherein the electrode elevation control unit performs control by the step control unit or the linear control unit immediately after the start of control. In order to add an electrode rod to the main electrode or the start electrode, at least a conveying means for transferring a spare electrode rod, an automatic electrode extension for automatically adding the spare electrode rod to the main electrode or the start electrode Control data is transmitted or received between the apparatus and the electrode elevation control means, the spare electrode bar is taken out from the storage location of the spare electrode bar, and the spare electrode bar is taken as the main electrode or The electric melting furnace control device according to any one of claims 1 to 4 , further comprising an electrode automatic extension control unit that performs control until the start electrode is automatically added. 6. The electric melting furnace control device according to claim 5 , wherein start-up control by the start-up control unit is automatically started after completion of automatic electrode-jointing by the electrode automatic-joining control unit.

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