JP2004257703A - Electric melting furnace controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric melting furnace controller capable of providing stable operation not affected by experience of an operator with respect to an electric melting furnace having a main electrode, a furnace bottom electrode, and a starting electrode. <P>SOLUTION: In the electric melting furnace controller 1, sending or exchange of control data is carried out between an electrode vertical movement control panel 23 moving electrode positions of the main electrode and the starting electrode in the furnace, and an electric power unit applying a voltage between each electrode, and operation control with respect to each electrode is carried out. It is provided with a starting control part 6 carrying out automatic operation control of the main electrode and the starting electrode in response to a state of an object to be melted at starting, and controlling the furnace until steady operation of melting the object to be melted is achieved just by automatic operation control of the main electrode, and an electrode vertical movement control part 7 carrying out movement control of the electrode position of the main electrode with respect to the electrode vertical movement control panel 23 so as to control voltages applied to the main electrode and the starting electrode at a set value during the steady operation. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes a main electrode, a bottom electrode, and a start electrode in a furnace, and a current generated by a high voltage applied between the main electrode and the bottom electrode or between the main electrode and the start electrode causes a current to be generated on the bottom electrode. The present invention relates to an electric melting furnace for melting an object to be melted, and more specifically, to an electric melting furnace control device for controlling operation of each electrode.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a melting furnace that melts incineration ash and dust generated in a garbage incineration facility to make it harmless and produces recyclable slag has been put into practical use. Various types of melting furnaces have been developed and put into practical use. However, the furnace has a main electrode (graphite electrode), a furnace bottom electrode, and a start electrode (graphite electrode). An electric melting furnace for melting an object 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 practically used for only several years.
[0003]
In the electric melting furnace, a DC voltage is applied between the main electrode and the furnace bottom electrode to generate a plasma arc to heat the molten slag and melt the sequentially supplied ash or the like. In addition, since current flows in the slag, Joule heat can be used and efficient melting is performed. The molten ash and the like becomes slag and is cooled after the continuous slag is discharged and discharged by a conveyor.
[0004]
The operation of the electric melting furnace is a control voltage value that is set while adjusting the distance between the main electrode and the bottom electrode while constantly adjusting the current value flowing between the main electrode and the bottom electrode during steady operation. The elevation control of the main electrode is performed.
[0005]
However, at the time of steady operation, the material to be melted is a molten slag, but at the start of operation, the material to be melted is not necessarily in a molten state, and the composition thereof is glassy or metallic, that is, conductive. The substance and the non-conductive substance are mixed, and the way of mixing is also uniformly mixed.When the heavy metal conductive substance is concentrated in the lower layer, the light glassy Non-conductive substances may be concentrated. Therefore, depending on the state of the material to be melted, a current flows between the main electrode and the furnace bottom electrode at the start of operation as in the case of the steady operation, and the operation can be shifted to the steady operation only by controlling the main electrode, No current flows between the main electrode and the furnace bottom electrode, the material to be melted is gradually melted from the upper layer using the start electrode, and finally, a state where current flows between the main electrode and the furnace bottom electrode is maintained. In some cases, the operation can be shifted to the steady operation, and complicated start-up control according to the state of the material to be melted is required.
[0006]
In addition, since the electrodes are made of graphite, they gradually wear due to the occurrence of plasma arc, so it is necessary to automatically add new electrode rods to the shortened electrode rods. .
[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 are the following Patent Documents 1 to 3 by the present applicant.
[0008]
[Patent Document 1]
JP-A-11-237018
[Patent Document 2]
JP 09-156529 A
[Patent Document 3]
JP-A-09-243267
[0009]
[Problems to be solved by the invention]
As described above, the operation of the electric melting furnace requires control at the start-up of the operation, control during the steady operation, and automatic electrode extension control, but the basic configuration of the electric melting furnace itself is as follows. Even though they are the same, various product specifications are caused by differences in the environment in which they are used, that is, garbage incineration facilities, etc., and the above-described respective controls are performed automatically or manually using respective independent control devices. There is. In addition, there has been a situation in which the contents of the above-mentioned respective controls have not been standardized in electric melting furnaces of many plants. For this reason, it sometimes depends on the experience of a somewhat skilled operator. This is because the electric melting furnace has only been used for several years, and there is not enough practical data to standardize and integrate the above controls until now. .
[0010]
Here, the inventor of the present application has arrived at the present invention in an effort to standardize and integrate the above-described respective controls based on past experience in practical use of an electric melting furnace. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to solve the above-mentioned problems and to realize an electric melting furnace capable of operating a stable electric melting furnace without being affected by the experience of an operator. It is to provide a control device.
[0011]
[Means for Solving the Problems]
A first characteristic configuration of the electric melting furnace control device according to the present invention for achieving this object includes a main electrode, a furnace bottom electrode, and a start electrode in a furnace, and a space between the main electrode and the furnace bottom electrode. Alternatively, in an electric melting furnace that melts a material to be melted on the furnace bottom electrode by a current generated by a high voltage applied between the main electrode and the start electrode, the inside of the furnace includes the main electrode and the start electrode. Electrode melting control means for transmitting or receiving control data between the electrode lifting / lowering control means for moving the electrode position in and the power supply device for applying a voltage between the respective electrodes, and controlling the operation of the respective electrodes. A furnace control device, which performs automatic operation control of the main electrode and the start electrode in accordance with the state of the material to be melted at the time of startup, and melts the material to be melted only by automatic operation control of the main electrode. For driving In the startup control unit to start up, during the steady operation, in order to control the voltage applied to the main electrode and the start electrode, to control the movement of the electrode position of the main electrode in the furnace to the electrode elevation control means And an electrode lifting / lowering control unit for the same.
[0012]
The current generated by applying a high voltage between the electrodes includes at least one of a discharge current of a plasma arc generated by the application of a high voltage and a current flowing in a conductive material of a material to be melted. , Usually both.
[0013]
According to the first characteristic configuration, the start control unit performs the automatic operation control of the main electrode and the start electrode according to the state of the material to be melted in the start-up control at the time of start-up. It can be used uniformly for various electric melting furnaces that start up using electrodes and start electrodes, and has both a start control unit and an electrode elevation control unit. Irrespective of the state, the control of raising and lowering the main electrode during the steady operation from the start-up control can be performed in an integrated manner. That is, the control of raising and lowering the electrode of the main electrode during the steady operation can be automatically performed from the start-up control, or a stable operation that is not affected by the experience of the operator can be performed even if the confirmation operation by the operator is involved.
[0014]
In the second characteristic configuration, the activation control unit starts lowering the main electrode after the control is started, determines a first current value flowing between the main electrode and the furnace bottom electrode, and determines the first current value. When the value is smaller than a predetermined first threshold, the main electrode is lowered to lower the main electrode to a predetermined lowering position. Then, the lowering of the start electrode is started, and the main electrode and the starter are started. A second current value flowing between the electrodes is determined, and when the second current value becomes equal to or more than a predetermined second threshold value, the start electrode is controlled to stop lowering the start electrode, and the main electrode and the start electrode are controlled. The present invention is characterized in that a current flows between the main electrode and the start electrode to melt the material to be melted while the electrode is kept at the lowering stop position.
[0015]
According to the second characteristic configuration, when the state of the material to be melted at the time of startup is a state in which a sufficient current cannot flow between the main electrode and the furnace bottom electrode, that is, in a solid state (non-molten state), The energization is performed between the main electrode and the start electrode while the descent stop positions of the two electrodes are almost in contact with the material to be melted. In general (for example, in normal arc welding, etc.), the discharge is performed at a certain interval from the object to be melted in order to obtain a high voltage to obtain high power in order to promote melting. By generating a plasma arc along the surface of the material to be melted while the descent and stop positions of the main electrode and the start electrode remain, the material to be melted from the surface of the material to the inside is efficiently and efficiently. Relatively high-speed melting becomes possible, and it is possible to shift to a steady operation at an early stage.
[0016]
The third characteristic configuration is that, in a state where the start control unit stops the main electrode and the start electrode at a predetermined descent stop position, a current flows between the main electrode and the start electrode, and When the start electrode is returned to the predetermined raising / stopping position after the material is melted, the starting electrode is raised in a plurality of times with a predetermined stop period interposed therebetween.
[0017]
According to the third characteristic configuration, the start electrode can be raised while cooling the start electrode by raising the start electrode stepwise, so that damage to the furnace wall close to the start electrode can be suppressed. .
[0018]
The fourth characteristic configuration is such that the electrode elevation control unit controls the movement of the electrode position of the main electrode by PID control, a step control unit performed by step control, and a linear control performed by linear control. It has a part.
[0019]
According to the fourth characteristic configuration, since a plurality of control units are provided, even if the control unit that is performing the electrode lifting / lowering control of the main electrode fails, another control unit immediately backs up the control unit. Control can be continued, and operation stop of the electric melting furnace can be avoided.
[0020]
The fifth characteristic configuration is that the electrode elevation control unit performs control by the step control unit or the linear control unit immediately after the control is started.
[0021]
According to the fifth characteristic configuration, since the state of the material to be melted is not stable immediately after the start of the control and the fluctuation is large, the step control unit having a good response to the PID control that requires a relatively long time for the control. Alternatively, by using the linear control unit, more stable control can be performed for a large fluctuation.
[0022]
The sixth characteristic configuration is that, in order to add an electrode rod to the main electrode or the start electrode, at least, a transport unit that transports a spare electrode rod, the spare electrode rod is attached to the main electrode or the start electrode. The automatic electrode extension device for automatically replenishing, and transmission or transmission and reception of control data between the electrode lifting and lowering control means, taking out the spare electrode rod from the storage location of the spare electrode rod, An automatic electrode extension control unit that controls until the electrode rod is automatically extended to the main electrode or the start electrode is further provided.
[0023]
According to the sixth characteristic configuration, the same electric melting furnace control device includes an electrode automatic extension control unit, so that the start-up control unit performs start-up control and the electrode lifting control unit controls the main electrode during steady operation. Elevation control and automatic electrode extension control by the electrode automatic extension control unit can be easily controlled in a uniform manner by linking them to each other instead of individually controlling each in the conventional electric melting furnace. become able to.
[0024]
The seventh characteristic configuration is that, after the automatic electrode extension by the electrode automatic extension controller ends, the start-up control by the activation controller is automatically started.
[0025]
According to the seventh characteristic configuration, it is possible to automatically restart the operation of the electric melting furnace stopped during the automatic electrode extension.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of an electric melting furnace control device according to the present invention (hereinafter, appropriately referred to as “the present invention device”) will be described with reference to the drawings.
[0027]
First, as shown in FIG. 2, an electric melting furnace 30 to be controlled by the apparatus 1 of the present invention is provided with a main electrode 31 and a start electrode 33 which penetrate through a furnace wall ceiling 35a and are inserted into a furnace 36. The electrodes are individually supported by an electrode lifting / lowering device 23a for the main electrode 31 and an electrode lifting / lowering device 23b for the start electrode 33, respectively, so that the tip positions of the respective electrodes in the furnace 36 can be moved up and down. A furnace bottom electrode 32 is provided on the furnace bottom 35b, and is connected to the current collector 34. The furnace side wall 35c is provided with a supply port 37 for the ash, which is the 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 a negative electrode of a DC power supply device 22a 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 via a support arm that supports the start electrode 33. The furnace bottom electrode 32 is connected via a current collector 34 to the other positive electrode of the DC power supply device 22a. An extra-high voltage is supplied to the DC power supply 22a via a VCB (vacuum breaker) 22b provided on a high-voltage switchboard.
[0028]
In the electric melting furnace 30 having the above-described configuration, a high DC voltage is applied between the main electrode 31 and the bottom electrode 32 to generate a plasma arc to heat the molten slag 40 on the bottom electrode 32 and to be sequentially supplied. Melts materials such as ash. In addition, since current flows in the slag, Joule heat can be used and efficient melting is performed. The molten ash or the like becomes slag, and is cooled after being discharged from a slag port 38 provided in the furnace side wall portion 35c, and discharged by a conveyor.
[0029]
As shown in FIG. 1, the apparatus 1 of the present invention includes a control operation processing unit 2, a control operation processing unit 2, an electrode lifting / lowering device control panel 23 of the electrode lifting / lowering devices 23 a and 23 b of the electric melting furnace 30, and a DC power supply 22 a. , An I / O interface 3 for transmitting and receiving control input / output data to and from the VCB 22b, and a display 4 for displaying various data. The three control functions of the start-up control of the furnace 30, the control of raising and lowering the main electrode during steady operation, and the automatic electrode extension control are exhibited.
[0030]
The control processing unit 2 comprises a central processing unit 5 composed of a general-purpose computer and a PID control unit 12 composed of a dedicated controller. The central processing unit 5 further includes a start control unit that exclusively performs the start-up control. 6, an electrode lifting / lowering control unit 7 for exclusively performing the main electrode lifting / lowering control during the normal operation, an electrode automatic / continuously extending control unit 8 for exclusively performing the above-mentioned electrode automatic continuation control, and a distributed control system used for control monitoring ( A DCS interface 9 for exchanging input / output data via a data link 21 which is a kind of computer network. The PID control unit 12 realizes a PID control function of executing the electrode elevation control of the electrode elevation control unit 7 by PID control with a dedicated controller, and forms a part of the electrode elevation control unit 7. The activation control unit 6 of the central processing unit 5, the electrode elevation control unit 7 excluding the PID control unit 12, and the automatic electrode extension control unit 8 execute programs by a general-purpose computer constituting the central processing unit 5. Is realized by software processing. Further, the electrode elevation control unit 7 in the central processing unit 5 executes a step control unit 10 for executing the electrode elevation control of the electrode elevation control unit 7 by step control by software processing, and an electrode elevation control of the electrode elevation control unit 7. In addition to the linear control unit 11 which is executed by linear control by software processing, management of which one of the step control unit 10, the linear control unit 11, and the PID control unit 12 performs the electrode elevation control, and the control between the control units And also manages when the control is taken over.
[0031]
The I / O interface 3 directly controls the electrode lifting / lowering device control panel 23, the DC power supply device 22a, the VCB 22b, the electrode automatic continuation device control panel 24 for directly controlling the electrode automatic continuation device 24a, and the electrode mounting table device 25a. Input / output of control input / output data is performed with the electrode mounting table control panel 25 via an individual communication line or a data link.
[0032]
In the present embodiment, in the automatic electrode extension control, input / output data for control with a furnace crane 26 that conveys a new electrode (spare electrode rod) from the electrode mounting device 25a to above the currently used old electrode is used. The exchange is performed via the DCS 20.
[0033]
Next, a processing procedure of the start-up control of the electric melting furnace 30 by the start 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.
[0034]
When a start command (# 0) by the operator is received from the DCS 20, confirmation of the status of each device (presence or absence of an alarm, etc.), pre-processing such as alarm display, and time delay processing by a timing timer are performed (# 1). A VCB input command is output to the VCB 22b (# 2). The VCB 22b is turned on by the VCB input command, and an extra-high voltage is supplied to the DC power supply 22a. Subsequently, after receiving the VCB input state input of the DCS 20, the main electrode lowering command is output to the electrode lifting device control panel 23 (# 3). The electrode lifting / lowering device control panel 23 starts lowering control for the electrode lifting / lowering 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 in the first current value I ₁ (Data) (# 4), the first current value I ₁ Is a predetermined first threshold value I _1A It is determined whether or not this is the case (# 5: initial current excess determination). First current value I ₁ Is the first threshold I _1A If it is smaller, the main electrode wire looseness data is received from the electrode lifting / lowering device control panel 23 (# 6), and the presence or absence of the main electrode wire looseness is determined (# 7). If there is no loose wire in the main electrode wire looseness determination, it is determined that the lower end of the main electrode 31 is not completely lowered, and the process returns to steps # 4 and # 5. Here, in the determination of step # 7, if there is a wire looseness, the main electrode 31 has been lowered to a lower position, so it cannot be lowered any further, 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 below.
[0035]
In the initial current excess determination in step # 5, the first current value I ₁ Is the first threshold I _1A In the case described above, since the material to be melted is in a conductive state (molten state) to some extent, the start-up control is completed without using the start electrode 33 only by applying a DC voltage between the main electrode 31 and the furnace bottom electrode 32. it can. (Startup control of the first pattern)
[0036]
In the start-up control of the first pattern, the first current value I ₁ Is the first threshold I _1A Then, a main electrode descent stop command is output to the electrode lifting / lowering device control panel 23 to stop the descent of the main electrode 31 (# 8). The electrode lifting / lowering device control panel 23 causes the electrode lifting / lowering device 23a to stop lowering the main electrode 31 in response to the main electrode descent stop command. Subsequently, a time delay process is performed by the main arc start timer (# 9), and the first current value I ₁ Is the first threshold I _1A Larger second threshold I _1B Until the above, the application of the DC voltage between the main electrode 31 and the furnace bottom electrode 32 is continued at the descent stop position of the main electrode 31 (# 10 to # 12). More specifically, the first current value I ₁ (Data) (# 10), the first current value I ₁ Is the second threshold I _1B It is determined whether the above is the case (# 11: second initial current excess determination), and the first current value I ₁ Is the second threshold I _1B Until the above, steps # 10 and # 11 are repeated, and a time delay process by the initial current over timer is performed in parallel (# 12). Note that the second initial current excess determination (# 10, # 11) is also performed during the time delay processing, and the first current value I ₁ Is the second threshold value I _1B Make sure it's over.
[0037]
First current value I ₁ Is the second threshold value I _1B As described above, after the time delay processing by the initial current over timer is completed, the voltage V between the main electrode 31 and the furnace bottom electrode 32 is changed. ₁ A main electrode raising command is output to the electrode lifting / lowering device control panel 23 in order to raise the lower end position of the main electrode 31 so that the voltage value becomes appropriate for starting the steady operation (# 13). The electrode lifting / lowering device control panel 23 starts the lifting control of the main electrode 31 with respect to the electrode lifting / lowering device 23a according to the main electrode lifting command.
[0038]
Voltage V between main electrode 31 and furnace bottom electrode 32 ₁ (#) Is received from the DC power supply device 22a (# 14), and the voltage value V ₁ Is a predetermined first threshold voltage V _1A Is determined (# 15). ₁ Is V _1A Until the above, steps # 14 and # 15 are repeated, and V ₁ Is V _1A Then, a main electrode lifting stop command is output to the electrode lifting device control panel 23 (# 16). First current value I ₁ Is determined to be equal to or greater than a predetermined current value, and after a predetermined post-processing (# 17) such as setting conditions at the start of the steady operation, the operation is shifted to the steady operation.
[0039]
Next, start-up control of the second pattern will be described. If it is determined in step # 7 that the wire is loose, a time delay process is performed by the start electrode activation timer (# 20), and the electrode lifting / lowering device is operated on the condition that the operator selects the use of the start electrode in the DCS20. A start electrode lowering command is output to the control panel 23 (# 21). The electrode lifting / lowering device control panel 23 starts lowering control for the electrode lifting / lowering device 23b for the start electrode 33 in response to the start electrode lowering command. As the start electrode 33 descends and approaches the surface of the material to be melted, the second current value I flowing between the main electrode 31 and the start electrode 33 according to the state of the material to be melted. ₂ In order to detect the change in the first current value I ₁ And the second current value I ₂ The third current value I which is the sum of ₃ (Data) (# 22), the third current value I ₃ Is a predetermined third threshold value I _3A It is determined whether this is the case (# 23: third initial current excess determination). Third current value I ₁ Is the third threshold value I _3A If it is smaller, the start electrode wire looseness data is received from the electrode lifting / lowering device control panel 23 (# 24), and it is determined whether or not the start electrode wire is loose (# 25). If there is no loose wire in the start electrode wire looseness determination, it is determined that the lower end of the start electrode 33 is not completely lowered, and the process returns to steps # 22 and # 23.
[0040]
Here, the third current value I ₃ Is the third threshold value I _3A If the wire is smaller and the wire is loose, the non-conductive substance is concentrated near the surface of the material to be melted and is in a solid state (non-molten state). An alarm is issued to the DCS 20 to take a measure to supply a conductive material to the DCS 20.
[0041]
In the third initial current excess determination in step # 23, the third current value I ₃ Is a predetermined third threshold value I _3A In the case described above, it is determined that a plasma arc is generated along the surface of the material to be melted between the main electrode 31 and the start electrode 33 at the lowered position of the start electrode 33 to melt the material to be melted. A stop electrode lowering stop command is output to the electrode lifter control panel 23 to stop the lowering of the electrode (# 26). The electrode lifting / lowering device control panel 23 causes the electrode lifting / lowering device 23b to stop lowering in response to 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 material to be melted while maintaining the stop positions of the respective electrodes, and the plasma arc and the downward heat generated by the plasma arc The material to be melted is gradually melted from the surface by conduction (# 27 to # 30). More specifically, while a high voltage is applied between the main electrode 31 and the start electrode 33, time delay processing is performed by a timing timer (# 27), and the first current value I is output from the DC power supply device 22a. ₁ (Data) (# 28), the first current value I ₁ Is the second threshold value I _1B (# 29: second initial current excess determination), and the first current value I ₁ Is the second threshold value I _1B Until the above, steps # 28 and # 29 are repeated, and time delay processing by the initial current over timer is performed in parallel (# 30). Note that the second initial current excess determination (# 28, # 29) is also performed during the time delay processing (# 30), and the first current value I ₁ Is the second threshold value I _1B Make sure it's over. As a result, the material to be melted is in a state in which the operation can be shifted to the steady operation sufficiently, and the process enters the end process (# 31 to # 46) to end the start-up control of the second pattern.
[0042]
First current value I ₁ Is the second threshold value I _1B As described above, after the time delay processing by the initial current over timer is completed, first, a VCB disconnection command is output to the VCB 22b (# 31). The VCB 22b is turned off by the VCB disconnection command, the supply of the extra-high voltage to the DC power supply 22a is cut off, and the application of the high voltage between the main electrode 31 and the furnace bottom electrode 32 and between the main electrode 31 and the start electrode 33 is stopped. It is released.
[0043]
Next, the main electrode support arm position data is received from the electrode lifting / lowering device control panel 23 (# 32), the main electrode support position is stored (# 33), and the main electrode lifting command is sent to the electrode lifting / lowering device control panel 23. Is output (# 34). The electrode lifting / lowering device control panel 23 starts lifting control on the electrode lifting / lowering device 23a for the main electrode 31 in response to the main electrode lifting command.
[0044]
While the main electrode 31 is being lifted, main electrode arm position data is received from the electrode lifting / lowering device control panel 23 (# 35), and the rising distance from the main electrode arm position stored in step # 33 and the current main electrode arm position is determined. While making the determination (# 36), the user increases the predetermined distance. After determining that the main electrode 31 has risen a predetermined distance, the main electrode 31 outputs a main electrode lifting stop command to the electrode lifting device control panel 23 (# 37). The electrode lifting / lowering device control panel 23 causes the electrode lifting / lowering device 23a to stop raising the main electrode 31 in response to the main electrode lifting / stopping command.
[0045]
Subsequently, the stepwise rising control of the start electrode (# 38 to # 46) is executed. Specifically, a start electrode raising command is output to the electrode lifting device control panel 23 (# 38). The electrode lifting / lowering device control panel 23 starts lifting control on the electrode lifting / lowering device 23b for the start electrode 33 in response to the start electrode raising command. A time delay process is performed by the timing timer (# 39), and a start electrode raising / stopping command is output to the electrode lifting / lowering device control panel 23 (# 40). The electrode lifting / lowering device control panel 23 causes the electrode lifting / lowering device 23b to stop lifting in response to a start electrode lifting / stopping command. Further, time delay processing is again performed by the timing timer (# 41), and a start electrode raising command is output to the electrode lifting device control panel 23 (# 42). The electrode lifting / lowering device control panel 23 again starts the lifting control on the electrode lifting / lowering device 23b for the start electrode 33 according to the start electrode raising command. Time delay processing is again performed by the timing timer (# 43), and a start electrode raising / stopping command is output again to the electrode lifting / lowering device control panel 23 (# 44). The electrode lifting / lowering device control panel 23 causes the electrode lifting / lowering device 23b to stop lifting in response to a start electrode lifting / stopping command. Start electrode arm position data is received from the electrode lifting / lowering device control panel 23 (# 45), and it is determined whether the start electrode arm position is at or above a predetermined height (# 46). Repeats the processes of steps # 38 to # 46 until the predetermined height is reached, and ends the startup control of the second pattern.
[0046]
Next, the electrode lifting control of the main electrode 31 by the electrode lifting controller 7 of the device 1 of the present invention will be described.
[0047]
The electrode lifting / lowering control unit 7 outputs various control commands to the electrode lifting / lowering apparatus control panel 23 using any one of the step control unit 10, the linear control unit 11, and the PID control unit 12, and outputs the main electrode. The lifting control is performed for the electrode lifting device 23a for 31. A first current value I flowing between the main electrode 31 and the furnace bottom electrode 32 is supplied to the DC power supply device 22a. ₁ By adjusting the distance between the main electrode 31 and the furnace bottom electrode 32 by raising and lowering the main electrode 31 while controlling the constant current so that the current becomes a constant current, the plasma voltage (V) applied between both electrodes is adjusted. ₁ ).
[0048]
The first current value I for the electrode elevation control unit 7 ₁ And voltage value V ₁ Are input from the DCS 20. Further, when the set values of the current and the voltage are changed from the DCS 20, the actual set values are gradually changed by the change rate setting. The change rate setting is switched for each control mode of the electrode elevation control. The control mode includes four control modes: 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 mode by manual operation. An increase rate and a decrease rate with respect to the voltage set value and the current set value are set in advance and are tabulated.
[0049]
Next, an outline of the electrode elevation control in the PID control mode by the PID control unit 12 will be described. The PID control unit 12 controls the voltage V received from the DC power supply 22a. ₁ The arithmetic processing is performed according to the processing procedure shown in FIG.
[0050]
First, the voltage V ₁ , A gap calculation for outputting the difference DV ′ based on the gap calculation characteristics shown in FIG. 7, and then performing the reverse operation to compensate for the difference DV ′. Is performed, and the main electrode lifting / lowering speed is output. The PID output is subjected to an output limiter process, and the main electrode lifting / lowering speed is output within a range of a predetermined output upper limit value and a predetermined output lower limit value. It should be noted that the gap width GW of the gap calculation, the respective set values of the proportional, integral, and derivative of the PID calculation, the output upper limit value and the output lower limit value of the output limiter process are set as set values.
[0051]
When the mode is shifted from another control mode to the PID control mode, the operation is performed from the output before the shift. Conversely, if the PID control unit 12 fails during the PID control, the control mode automatically shifts to the control mode (step control mode or linear control mode) set in advance in the PID control failure control mode.
[0052]
Next, an outline of the electrode control in the step control mode by the step control unit 10 will be described. The step controller 10 controls the voltage V received from the DC power supply 22a. ₁ The arithmetic processing is performed according to the processing procedure shown in FIG.
[0053]
First, the voltage V ₁ And the voltage setting value is determined, and it is determined which of the six regions shown in FIG. 8 corresponds to the deviation DV, and the electrode lifting / lowering device control panel 23 performs five types of electrode lifting / lowering control. . That is, four deviation determination thresholds of ΔV1, ΔV2, −ΔV1, and −ΔV2 are set (however, ΔV2> ΔV1), the first descending operation is performed when DV ≧ ΔV2, and the deviation operation is performed when ΔV2> DV ≧ ΔV1. The second descending operation is performed by performing a first ascending operation when DV ≦ −ΔV2, a second ascending operation when −ΔV2 <DV ≦ −ΔV1, and any elevating operation when −ΔV1 <DV <ΔV1. Also do not execute.
[0054]
The first descent operation and the first elevating operation, and the second descent operation and the second elevating operation, respectively, have the same operation time and stop time during each control, except that the moving directions of the electrodes are opposite. On the other hand, the first descent operation and the second descent operation, and the first ascent operation and the second ascent operation have the same moving direction of the electrodes, respectively, but the operation time during each control and the set value of the stop time are different. Each of the first operations is set to perform a large descending or ascending.
[0055]
Accordingly, when any one of the first descending operation, the second descending operation, the first ascending operation, and the second ascending operation is selected in the manner described above, the step control unit 10 determines the operation time and the stop time of each operation. 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 raising and lowering device 23a for the main electrode 31. If no operation is selected, no elevation control command is output.
[0056]
Next, an outline of the electrode control in the linear control mode by the linear control unit 11 will be described. The linear controller 11 controls the voltage V received from the DC power supply 22a. ₁ The arithmetic processing is performed according to the processing procedure shown in FIG.
[0057]
First, the voltage V ₁ , A gap calculation for outputting the difference DV ′ based on the gap calculation characteristics shown in FIG. 7, and then performing the reverse operation to compensate for the difference DV ′. Is performed (refer to the ratio calculation equation of Equation 1), and the main electrode lifting / lowering speed R is output.
[0058]
## EQU1 ## R = GA.DV '+ BI
[0059]
An output limiter process is performed on the ratio calculation output R to output a main electrode elevating speed within a range of a predetermined output upper limit value and a predetermined output lower limit value. Here, the gap width GW of the gap calculation, the gain GA and the bias BI of the ratio calculation expression, the output upper limit value and the output lower limit value of the output limiter process are set as the set values, respectively. The gap width GW of the gap calculation may be the same as or different from that in the PID control mode.
[0060]
The electrode elevation control unit 7 selects a preset step control mode or linear control mode at the time of starting the electrode elevation 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 has stabilized.
[0061]
Next, an outline of a processing procedure in the electrode automatic extension control of the main electrode 31 by the electrode automatic extension control unit 8 of the device 1 of the present invention will be described with reference to a flowchart of FIG. In the present embodiment, for a plurality of electric melting furnaces 30, an electrode automatic extension device 24a and an electrode automatic extension device control panel 24 necessary for automatic electrode extension, an electrode mounting device 25a, and an electrode mounting device control device. The electrode automatic extension control when the panel 25 and the top crane 26 are shared will be described. However, in the present embodiment, the apparatus 1 of the present invention is provided separately for each electric melting furnace 30, and the automatic electrode extension control unit 8 is also controlled by the electric melting furnace 30 (hereinafter referred to as “own furnace” as appropriate). ) Is performed. In the following description, each process in each process is executed by the electrode automatic extension control unit 8 unless otherwise specified.
[0062]
First, the extension preparation step (# 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. If it is possible, a message to that effect is sent to the DCS 20. Output. Upon receiving a command to start the extension from the DCS 20, the operator outputs a selection command to the top crane 26, which operates the own furnace, to the effect that the electrode has been selected for automatic electrode extension control. Each state data for confirming the presence or absence of abnormality is obtained from each of the devices 23 to 26, and further, the start electrode arm position data is received from the electrode lifting / lowering device control panel 23, and it is determined whether or not the electrode automatic extension operation is possible. . If there is no abnormality in any of them, a continuation preparation command is output to the electrode automatic continuation device control panel 24 and the furnace top crane 26. The electrode automatic extension device control panel 24 and the furnace top crane 26 execute a predetermined extension operation when they receive the extension instruction, and output to the automatic electrode extension control unit 8 when the operation is completed. Upon receiving the extension preparation operation end data from both the electrode automatic extension device control panel 24 and the top crane 26, a message to that effect is output to the DCS 20.
[0063]
Next, the automatic extension step (# 110) will be described. On the basis of the message of the end of the DCS 20 preparation operation, the operator issues an automatic start command on the DCS 20 and, when the command is received from the DCS 20, transmits an automatic start command to the related devices. In the automatic extension step (# 110), first, the electrode dispensing step (# 111) is executed.
[0064]
In the electrode dispensing step (# 111), when the electrode table controller 25 receives the automatic extension start command, the electrode table 25a performs a predetermined electrode dispensing operation, and a new electrode can be taken out. When receiving the electrode take-out data from the electrode stand device control panel 25, it sends a new electrode preparation command to the electrode automatic extension device control panel 24.
[0065]
Subsequent to the electrode dispensing step (# 111), the ash supply stopping step (# 112) for stopping the ash supply operation during the ash supply operation and the new electrode gripping step (# 113) are executed in parallel. In the new electrode gripping step (# 113), when the automatic electrode extension device control panel 24 receives a new electrode preparation command, the automatic electrode extension device 24a performs an operation of gripping a new electrode. In this operation, at the same time, a male screw joint member screwed to the female screw portion at the upper end of the old electrode is attached to the female screw portion at the tip (lower end) of the new electrode.
[0066]
Subsequent to the new electrode gripping step (# 113), in the crane intermediate point moving step (# 114), a crane intermediate point moving command is output to the furnace crane 26, the furnace crane 26 receives the command, and Move to the middle point.
[0067]
Subsequently, the electrode operation stopping step (# 115) is executed. Specifically, after the top crane 26 moves to the intermediate point and confirms that the ash supply operation has stopped, when the VCB 22b is in the ON state, that is, when a very high voltage is supplied to the DC power supply 22a, When a high voltage is applied, an instruction 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 / lowering control are released, after a lapse of a predetermined second, an electrode standby position lifting / lowering command is output to the electrode lifting / lowering device control panel 23, and the electrode lifting / lowering device control panel 23 outputs the command. Upon receipt, the main electrode 31 is raised or lowered to a predetermined standby position.
[0068]
At the start of the electrode operation stopping step (# 115), if the electrode lifting / lowering control unit 7 is performing the electrode lifting / lowering control of the main electrode 31 with respect to the electrode lifting / lowering device control panel 23, the DC power supply device 22a, and the VCB 22b, The control of the extension control unit 8 is executed prior to the electrode elevation control of the electrode elevation control unit 7, and the electrode elevation control by the electrode elevation control unit 7 is interrupted.
[0069]
Subsequent to the electrode operation stopping step (# 115), in the crane splicing point moving step (# 116), first, a command to open the handrail passage gate, which is an obstacle to the movement of the furnace top crane 26, is output to the DCS 20, It receives the handrail gate open state data from the DCS 20 and outputs a crane splice point movement command to the furnace top crane 26. The top crane 26 receives the command, and moves the crane to the extension point. Subsequently, an N2 desorption device opening command is output to the electrode lifting / lowering device control panel 23, and confirmation data for opening the N2 desorption device of the electrode lifting / lowering device 23a is received from the electrode lifting / lowering device control panel 23.
[0070]
Next, after the furnace top crane 26 moves to the extension point, in the electrode automatic extension apparatus cover lowering step (# 117), an electrode automatic extension apparatus cover lowering command is output to the electrode automatic extension apparatus control panel 24. Then, the automatic electrode extension device 24a executes the cover lowering process.
[0071]
Subsequently, in the crane extension point moving step (# 116), confirmation data of opening of the N2 desorption device of the electrode lifting / lowering device 23a is received from the electrode lifting / lowering device control panel 23, and in the crane lowering / main electrode raising process (# 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 extension height has been reached from the furnace top crane 26 or whether crane lowering has been completed, a main electrode lifting command is output to the electrode lifting device control panel 23. The electrode lifting / lowering device 23a starts to raise the main electrode 31 and receives the old electrode top position detection data from the electrode automatic extension device control panel 24, and sends the main signal to the electrode lifting / lowering device control panel 23 based on the position detection data. An electrode rising stop command is output, and the main electrode 31 stops rising.
[0072]
Subsequently, in the electrode extension process (# 119), an electrode extension command is output to the electrode lifting / lowering device control panel 23, and the electrode lifting / lowering device control panel 23 uses the command to add the new electrode to the old electrode. Perform the action. After the completion of the extension operation, the end notification is received, and a termination operation end message is output to the DCS 20.
[0073]
Subsequently, an electrode gripping step (# 120) is executed. At the end of the electrode extension step (# 119), the old electrode is supported by the electrode support arm of the electrode lifting and lowering device 23a, and the new electrode is supported by the automatic electrode extension device 24a. Therefore, in a state where the new electrode is supported by the electrode automatic extension device 24a, an electrode gripping command is output to the electrode lifting / lowering device control panel 23, and the electrode lifting / lowering device 23a changes the supporting point from the old electrode to the new electrode. Moving. When the electrode gripping is completed, a new electrode release command is output to the electrode automatic extension device control panel 24 to cause the automatic electrode extension device 24a to release the support of the new electrode.
[0074]
When the automatic electrode extension device 24a completes the new electrode releasing operation, a crane retreating step (# 121) is executed, and the furnace top crane 26 executes a crane hoisting operation, an intermediate point moving operation, and the like. Subsequently, in the post-processing step (# 122), a command to close the handrail passing date is output to the DCS 20, and the handrail passing gate closed state data is received from the DCS 20, and the N2 desorption device mounting command is sent to the electrode lifting / lowering 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.
[0075]
When the completion of the post-processing step (# 122) is confirmed, the electrode automatic extension control unit 8 instructs the activation control unit 6 to control the startup of the electric melting furnace 30 (# 123). After the start-up control by the activation control unit 6 is completed, when the operation shifts to the steady operation by the electrode lifting and lowering control unit 7, an ash supply operation start command is output to the ash supply device (# 124). When the confirmation data indicating that the ash supply operation is being performed from the ash supply device is received and the completion of the evacuation operation of the furnace top crane 26 in the crane evacuation process (# 121) is confirmed, the DCS 20 is sent to the DCS 20 in the end process (# 125). , An automatic extension completion message is output, and an automatic extension completion confirmation command is received from the DSC 20 by an operator, and an automatic extension control completion instruction is output to the furnace top crane 26, and the electrode automatic extension of the main electrode 31 is performed. End the foot control.
[0076]
As described above, since the device 1 of the present invention integrally includes the activation control unit 6, the electrode elevation control unit 7, and the automatic electrode extension control unit 8, the electric control for the automatic electrode extension control of the main electrode 31 is performed. The start-up control of the melting furnace 30 and the automatic elevating control of the main electrode 31 during the steady operation are automatically and smoothly executed, and the electrode automatic extension control of the main electrode 31 can be ended.
[0077]
Hereinafter, another embodiment will be described.
In the above embodiment, the description has been made on the premise that the present invention apparatus 1 is provided separately for each electric melting furnace 30. However, one present invention apparatus 1 simultaneously operates a plurality of electric melting furnaces 30. The control form may be used.
[0078]
The specific operation, processing procedure, and configuration of each control unit of the activation control unit 6, the electrode elevation control unit 7, and the electrode automatic extension control unit 8 of the device 1 of the present invention are the same as those of the above embodiment. The configuration is not limited, and can be appropriately changed within the technical scope of the present invention.
[0079]
For example, the PID control unit 12 of the electrode lifting / lowering control unit 7 may be realized by software processing similarly to the step control unit 10 and the linear control unit 11 without using a dedicated controller. Further, the electrode automatic extension control by the electrode automatic extension control unit 8 may be executed for the start electrode 33.
[0080]
【The invention's effect】
As described above, according to the present invention, stable start-up control of the electric melting furnace not affected by the experience of the operator, automatic raising and lowering control of the main electrode at the time of steady operation, and further, automatic electrode extension control of the main electrode can be performed. 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 configuration conceptual diagram of an electric melting furnace to be controlled by an electric melting furnace control device according to the present invention.
FIG. 3 is a flowchart showing a processing procedure of start-up control of an electric melting furnace.
FIG. 4 is a flowchart showing a processing procedure of start-up control of an electric melting furnace.
FIG. 5 is a flowchart showing a processing procedure of start-up control of the electric melting furnace.
FIG. 6 is a process diagram illustrating a processing procedure of PID control by a PID control unit.
FIG. 7 is a diagram showing input / output characteristics used for gap calculation.
FIG. 8 is an explanatory diagram illustrating a processing procedure of step control by a step control unit.
FIG. 9 is a process diagram illustrating a processing procedure of linear control performed by a linear control unit.
FIG. 10 is a flowchart showing a processing procedure of electrode automatic extension control;
[Explanation of symbols]
1: Electric melting furnace control device according to the present invention
2: Control operation processing unit
3: I / O interface
4: Display
5: Central processing unit
6: Start control unit
7: Electrode lifting control unit
8: Electrode automatic extension control section
9: DCS interface
10: Step control unit
11: Linear control unit
12: PID control unit
20: Distributed control system (DCS)
21: Data link
22a: DC power supply
22b: VCB (vacuum 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 table control panel
25a: Electrode mounting device
26: Furnace 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 (7)

A main electrode, a bottom electrode, and a start electrode are provided in the furnace, and a current generated by a high voltage applied between the main electrode and the bottom electrode or between the main electrode and the start electrode is applied to the bottom electrode. In the electric melting furnace to melt the material to be melted in,
Electrode lifting control means for moving the electrode position in the furnace of the main electrode and the start electrode, and, between the power supply device for applying a voltage between the respective electrodes, transmission or transmission of control data, An electric melting furnace control device that performs operation control on each of the electrodes,
At the time of start-up, start-up control for performing automatic operation control of the main electrode and the start electrode in accordance with the state of the material to be melted, and starting up to a steady operation for melting the material to be melted only by automatic operation control of the main electrode. Department and
During steady operation, to control the voltage applied to the main electrode and the start electrode, an electrode elevation control unit that performs movement control of the electrode position of the main electrode in the furnace with respect to the electrode elevation control means. An electric melting furnace control device, comprising: The start control unit starts lowering the main electrode after the control is started, determines a first current value flowing between the main electrode and the furnace bottom electrode, and determines that the first current value is higher than a predetermined first threshold value. When it is smaller, the lowering control of the main electrode to lower the main electrode to a predetermined lowering position is performed, and subsequently, the lowering of the start electrode is started, and the second current value flowing between the main electrode and the start electrode is controlled. When the second current value is equal to or more than a predetermined second threshold value, the start electrode is controlled to lower to stop the lowering of the start electrode,
2. The electric melting furnace according to claim 1, wherein an electric current is applied between the main electrode and the start electrode to melt the material to be melted while the descent and stop positions of the main electrode and the start electrode remain. 3. Control device. The start control unit, in a state where the main electrode and the start electrode are stopped at a predetermined descent stop position, after flowing a current between the main electrode and the start electrode to melt the object to be melted, The electric system according to claim 1, wherein when the electrode is returned to a predetermined stop position, the start electrode is raised in a plurality of times with a predetermined stop period therebetween. Melting furnace 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 any one of claims 1 to 3. 5. The electric melting furnace control device according to claim 4, wherein the electrode raising / lowering control unit performs control by the step control unit or the linear control unit immediately after starting the control. 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 an electrode automatic extension for automatically adding the spare electrode rod to the main electrode or the start electrode. Device, and, between the electrode lifting and lowering control means, transmits or receives control data, takes out the spare electrode rod from the storage location of the spare electrode rod, the spare electrode rod the main electrode or The electric melting furnace control device according to any one of claims 1 to 5, further comprising an electrode automatic extension control unit that controls until the start electrode is automatically extended. 7. The electric melting furnace control device according to claim 6, wherein after the electrode automatic extension is completed by the electrode automatic extension control unit, the start-up control by the activation control unit is automatically started. 8.

Images