JP4853094B2 - Melting control method and apparatus during startup of electric resistance ash melting furnace - Google Patents

Description

  The present invention relates to a melting control method and apparatus for an electric resistance ash melting furnace in which an electrode charged in the furnace is energized to melt ash, and more particularly to control during startup of an electric resistance ash melting furnace. Is.

  An example of an electric resistance type ash melting furnace for melting incineration ash such as municipal waste incineration ash is shown in FIG. As shown in FIG. 4, the electric resistance ash melting furnace includes a melting furnace 53, an incineration ash charging device 54, a power supply device 55, and a molten slag solidifying device 56. A slag outlet 59 that is opened and closed by a slag outlet gate 60 and a molten metal discharge port 61 (usually closed) are installed on the side wall of the furnace main body 57 that is the main component of the melting furnace 53. The device 54 includes a hopper 62, a cutting device 63, a chute 64, and an input amount setting device 65. The power supply device 55 includes a power calculator 66, a power controller 67, a power transformer 68, and electrodes 58a, 58b, and 58c. This electric resistance type ash melting furnace supplies AC power to the three electrodes 58 a, 58 b, 58 c inserted from the upper part of the melting furnace 53, and energizes the incinerated ash 50 and the molten slag 51 introduced by the charging device 54. It melts using heat generated by Joule heat during energization.

  The electric resistance ash melting furnace configured as described above is operated as follows. Based on the input amount set by the input amount setting device 65, a certain amount of incineration ash 50 is input into the furnace main body 57 per hour. The electric power calculator 66 calculates electric power according to the input amount of the incineration ash 50 and supplies electric power necessary for melting to the electrodes 58a, 58b, 58c. When melting progresses and the molten metal surface of the molten slag 51 in the furnace body 57 rises to a predetermined position, the slag outlet gate 60 is opened, and the molten slag 51 is discharged and solidified by the solidifying device 56. By repeating this, the incineration ash 50 is melted. During this operation, the power supply amount is set and adjusted so as to maintain a constant temperature by monitoring the temperature of the discharged molten slag 51, the furnace temperature of the furnace body 57, the cooling water temperature of the furnace body 57, or the like. Is done. By operating in this way, the molten slag 51 can be automatically controlled relatively easily to an appropriate temperature. When a predetermined amount or more of the molten metal 52 is accumulated in the furnace body 57, the molten metal discharge port 61 is opened and discharged.

  On the other hand, the refractory constituting the furnace body is a consumable item, and if the operation is performed for a certain period of time, all of the molten slag and molten metal in the furnace body are discharged, and inspection / repair in the furnace is required. In this case, after the furnace body is cooled to room temperature, inspection / repair work is performed, so it is necessary to bring it back up to the operation state. When starting up, an electrode is lowered on a conductive material such as carbon powder laid on the bottom of the furnace, and an incineration ash is placed on the electrode to energize, thereby melting a part of the incineration ash. Then, while adjusting the electrode height and the amount of incinerated ash input, the temperature in the furnace and the power value to be continuously operated are gradually increased.

  Since the temperature inside the furnace is adjusted manually by the operator at the time of start-up, a thermal shock acts on the refractory in the furnace due to a delay in thermal response or rapid heating, causing damage such as cracking or dropping of the refractory. Occurring and reducing the usable life of the melting furnace.

As a method for solving this problem, for example, by controlling the amount of incinerated ash charged into the furnace according to the deviation between the furnace temperature target value and the measured temperature value, the furnace temperature is automatically controlled to an appropriate value. It has been proposed that damage to the refractory can be prevented in advance (see, for example, Patent Document 1).
JP 2000-213728 A

  However, in the method disclosed in Patent Document 1, since the amount of incineration ash charged into the furnace is controlled according to the deviation between the furnace temperature target value and the actual measurement value, an amount that is excessive or insufficient depending on the deviation. Incineration ash may be introduced, and there is a problem that the optimum amount of incineration ash cannot be introduced when the ash melting furnace is started up.

  The present invention has been made to solve the above problems, and in starting up an electric resistance ash melting furnace, an optimal amount of incineration ash can be introduced without damaging the refractory, It is an object of the present invention to provide a melting control method and apparatus for an electric resistance ash melting furnace that can be automatically started.

Melting control method when starting an electric resistance type ash melting furnace according to the present invention, start-up time of the melting method of controlling the electric resistance type ash melting furnace by energizing the electrodes were charged into the furnace to melt the ash A step of setting a temperature increase target value of the furnace temperature at each elapsed time from the start of the ash melting furnace to a steady operation state as a time schedule of the temperature increase target value, and a time schedule of the temperature increase target value Corresponding to the step of setting the target amount of ash into the furnace at each elapsed time as a time schedule of the target amount of input, a step of measuring the furnace temperature, and The electric power supplied to the electrode is controlled in accordance with the deviation between the step of introducing ash into the furnace based on the time schedule and the temperature rise target value of the set time schedule and the measured value of the measured furnace temperature. and a step, When the inner temperature has reached a predetermined temperature, the process proceeds to the steady operation.

Melting controller when starting the electric resistance type ash melting furnace according to the present invention, the melt control device by energizing the electrodes were charged into the furnace during start-up of the electric resistance type ash melting furnace for melting the ash A temperature setting means for setting a temperature increase target value of the furnace temperature at each elapsed time from the start of the ash melting furnace to a steady operation state as a time schedule of the temperature increase target value; Corresponding to the time schedule, the input amount setting means for setting the target amount of ash input into the furnace at each elapsed time as the time schedule of the input amount target value , the thermometer for measuring the furnace temperature, and the input amount a dosing means for introducing the ash into the furnace based on the time schedule of dosages target value set by the setting means, measurement by the thermometer and a heating target value of the temperature setting means by a set time schedule And a power supply control means for controlling the power supplied to the electrode in accordance with the deviation between the actual measurement value of the temperature the furnace, when the furnace temperature reaches a predetermined temperature, shifts to the steady operation.
In the present invention, setting the target amount of ash injection or the target temperature increase value in a program form means that the target value is changed along with the elapsed time (time schedule setting). It is assumed that not only digital processing by a processor or the like but also analog processing is included.

  In the present invention, the target value of ash input into the furnace is set in a program form, and the time schedule of the target amount of input is set, so that incinerated ash can be input in an optimum amount. At the same time, the temperature setting means presets the temperature rise target value of the furnace temperature from the start-up to the steady operation state in advance according to the deviation between the temperature rise target value and the measured value of the furnace temperature. By controlling the power supplied to the electrodes, the furnace temperature can be controlled to the target value. For this reason, the thermal shock of the refractory in the furnace can be suppressed, damage to the refractory can be prevented, and start-up is automatically performed when an electric resistance ash melting furnace is newly installed or refractory is repaired. be able to. Further, since both the ash charging amount and the furnace temperature can be automatically controlled, the operation at the time of start-up can be performed with a very small number of operators and without the need for skilled operators.

  The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of an embodiment of the present invention, and is a schematic system diagram of an electric resistance ash melting furnace.

  As shown in FIG. 1, the furnace body 4 that melts the incineration ash 1 such as municipal waste incineration ash inside has an outer shell covered with an iron skin 28, and a refractory 29 is installed in the inside. The side wall of the furnace body 4 has a slag outlet 23 for discharging the molten slag 2 generated by melting the incinerated ash 1 and a molten metal discharge for discharging the molten metal 3 generated when the incinerated ash 1 is melted. The slag outlet 23 is opened and closed by a slag outlet gate 24, and the molten metal discharge port 25 is opened and closed by a molten metal hot water gate 26, respectively. And the upper opening part of the furnace main body 4 is covered with the furnace cover 5, The duct 27 connected with a dust collector (not shown) is installed in the furnace cover 5. As shown in FIG.

  Above the furnace body 4, a hopper 19 for storing the incineration ash 1 is installed inside. The incineration ash 1 in the hopper 19 is cut out by a cutting device 21 installed at the lower part of the hopper 19, and the furnace It is put into the furnace body 4 through a chute 22 that penetrates the lid 5. The hopper 19 is supported by the load cell 20, and the weight of the hopper 19 including the incineration ash 1 is measured by the load cell 20, and this weight measurement value is an input amount control for controlling the input amount of the incineration ash 1 into the furnace body 4. It is transmitted to the board 18.

  The input amount control panel 18 is connected to an input amount program setting device 17 for setting the input amount of the incinerated ash 1 into the furnace body 4 in a program form. The input amount program setting unit 17 outputs the input amount target value at each elapsed time from the start of input to the input amount control panel 18 based on the time schedule of the input amount target value input in advance.

  The input amount control panel 18 compares the target value of the input amount for each elapsed time input from the input amount program setting unit 17 with the actual value of the input amount measured by the load cell 20 and responds to the deviation. Thus, the control output to the cutting device 21 is changed so that the deviation is reduced. Based on this command, the cutting device 21 adjusts the cutting amount to adjust the feeding amount.

  The furnace lid 5 is provided with three electrodes 6a, 6b and 6c passing through the furnace lid 5. The electrodes 6 a, 6 b, 6 c are respectively held by the electrode support arms 9, and the electrodes 6 a, 6 b, 6 c are moved up and down in the furnace body 4 by operating the hydraulic cylinder 10 connected to the electrode support arms 9. It is possible. In FIG. 1, the electrode supporting arms that hold the electrodes 6b and 6c and the hydraulic cylinders that are connected to these electrode supporting arms are omitted.

  The electrodes 6a, 6b, and 6c are connected to the power transformer 7, and the three-phase AC power is supplied from the power transformer 7. A primary voltage adjusting device 8 is installed on the primary side of the power transformer 7, and the primary side of the power transformer 7 is adjusted by the primary voltage adjusting device 8 to adjust the secondary side of the power transformer 7. Is adjusted, and the power supplied to the secondary-side electrodes 6a, 6b, 6c is adjusted.

  The electrodes 6a, 6b, and 6c are provided with an ammeter 11, a voltmeter 12, and a wattmeter 13, respectively. The current and voltage supplied to the electrodes 6a, 6b, and 6c by the ammeter 11 and the voltmeter 12 respectively. Each is measured. The measured current value and voltage value are input to the wattmeter 13, and the power supplied to each electrode 6a, 6b, 6c is measured. Then, the total power measured by the electrodes 6 a, 6 b and 6 c is input to the power control panel 15. In FIG. 1, an ammeter, a voltmeter and a wattmeter for measuring the power supplied to the electrodes 6b and 6c are omitted.

  Connected to the power control panel 15 is a temperature program setter / power calculator 14 that outputs a target value of power supplied to the electrodes 6 a, 6 b, 6 c to the power control panel 15. The power control panel 15 compares the target power value for each elapsed time input from the temperature program setter / power calculator 14 with the total power of the electrodes 6a, 6b, 6c measured by the power meter 13. Then, according to the deviation, the control output to the primary voltage regulator 8 is changed so that the deviation is reduced. Based on this command, the primary voltage adjustment device 8 adjusts the primary voltage of the power transformer 7 to adjust the power supplied to the electrodes 6a, 6b, 6c. In this embodiment, instead of or in addition to this, for example, a command from the power control panel 15 is given to the hydraulic cylinder 10 to change the height of the electrodes 6a, 6b, 6c to control the supplied power. You may make it do.

  In the temperature program setter / power calculator 14, the temperature increase target value of the furnace temperature at each elapsed time from the start of energization is set in advance as a time schedule for the temperature increase target value. The temperature program setter / power calculator 14 is connected to a thermometer 16 for measuring the furnace temperature, and a measured value of the furnace temperature by the thermometer 16 is transmitted. The thermometer 16 is composed of a thermocouple or the like, and is installed in the furnace through the furnace lid 5. It is preferable that the temperature measurement position is a space position in the furnace that is not immersed in the incinerated ash 1 or the molten slag 2 that has been charged. This is because the furnace temperature can be stably controlled without being directly affected by the incinerated ash 1 or the heated molten slag 2 having a low temperature immediately after charging. .

  The temperature program setter / power calculator 14 compares the target temperature increase value for each elapsed time set in advance with the actually measured value of the furnace temperature measured by the thermometer 16 and responds to the deviation. In order to reduce the deviation, that is, to calculate the optimum power target value for each elapsed time of power supplied to the electrode so that the measured value of the furnace temperature is close to the temperature rise target value. Output to the control panel 15.

  By configuring the control device of the ash melting furnace in this way, it is optimal that there is no excess or deficiency in each elapsed time from the start of charging based on the time schedule of the input amount target value input in advance from the start to the steady operation state. The amount of incinerated ash can be charged in an amount, and the electric power supplied to the electrodes can be controlled so as to raise the furnace temperature based on the time schedule of the temperature rise target value of the furnace temperature inputted in advance.

  In the present embodiment, the temperature program setting / calculating unit 14 corresponds to the temperature setting means of the present invention, and the electrodes 6a, 6b, 6c, ammeter 11, voltmeter 12, wattmeter 13, primary voltage. The adjusting device 8, the hydraulic cylinder 10 and the power control panel 15 correspond to the supplied power control means of the present invention, and the input amount program setting device 17 corresponds to the input amount setting means of the present invention. The input amount control panel 18 and the load cell 20 The cutting device 21 and the chute 22 correspond to the charging means of the present invention.

A method for starting up the electric resistance ash melting furnace having the above configuration will be described below.
First, before starting up, the time schedule of the target value of the ash input amount is input to the input amount program setter 17 in advance, and the time schedule of the temperature increase target value of the furnace temperature is input to the temperature program setter / power calculator 14. Enter. Before and after this, a conductive substance such as carbon powder was laid on the bottom of the furnace body 4, the tips of the electrodes 6 a, 6 b, 6 c were brought into contact therewith, and the incineration ash 1 was previously charged thereon. deep. The amount of incineration ash 1 charged is, for example, about 150 mm deep in the furnace body 4.

  The time schedule for the temperature rise target value of the furnace temperature needs to be set so that the refractory 29 is not damaged by the thermal shock, but this thermal shock varies depending on the material of the refractory 29 and the size of the furnace body 4. Therefore, it is difficult to make a general decision, so it is important to try as a moderate temperature rise pattern at the first start-up and to experience the start-up several times to understand the optimum temperature rise pattern . Similarly, it is important that the time schedule of the target value of the ash input amount is experienced several times to grasp the optimum pattern.

  Next, energization of the electrodes 6a, 6b, 6c is started. As described above, the adjustment of the power supplied to the electrodes 6a, 6b, and 6c is performed by comparing the power target value calculated by the temperature program setter / power calculator 14 with the power measured by the wattmeter 13 as a deviation. The primary voltage adjustment device 8 adjusts the primary voltage of the power transformer 7 and controls the raising and lowering positions of the electrodes 6a, 6b, 6c by the hydraulic cylinder 10 so that the number of the electrodes 6a, 6b, 6c is controlled.

  The furnace temperature rises as the energization starts. As described above, the adjustment of the furnace temperature is performed by comparing the target temperature increase value input to the temperature program setter / power calculator 14 with the actually measured value of the furnace temperature measured by the thermometer 16. An optimal power target value is calculated so as to reduce the deviation, the power target value is output to the power control panel 15, and the power supplied to the electrodes is controlled.

  An example of this furnace temperature control method will be described in detail with reference to FIG. FIG. 2 is an example of a flowchart of a power control method incorporated in the temperature program setter / power calculator 14 and the power control panel 15.

  As shown in FIG. 2, the actually measured value of the furnace temperature by the thermometer 16 is compared with the target value of the temperature for each elapsed time input from the temperature program setter / power calculator 14 (S11). If the measured value is higher than the target value (YES), a power target value corresponding to the deviation is calculated and obtained (S12). Then, as a result of the calculation, the reduced power target value is output, and the control output from the power control panel 15 to the primary voltage regulator 8 is changed to lower the voltage, or instead of or in addition thereto, The power control panel 15 changes the control output to the hydraulic cylinder 10 to raise the positions of the electrodes 6a, 6b, 6c, thereby adjusting the power supplied to the electrodes 6a, 6b, 6c to be reduced (S13, S14). If the actual measurement value is lower than the target value (NO), the power target value corresponding to the deviation is calculated and obtained (S15). Then, as a result of the calculation, an increased power target value is output, and the voltage is increased by changing the control output from the power control panel 15 to the primary voltage regulator 8, or instead of or in addition thereto. The power control panel 15 changes the control output to the hydraulic cylinder 10 to lower the positions of the electrodes 6a, 6b, 6c, thereby adjusting the power supplied to the electrodes 6a, 6b, 6c to increase (S16). , S17). Then, unless there is an end command (S18), the process returns to the above process (S11) and a series of processes are repeated.

  Further, the charging control panel 18 controls the cutting device 21 based on the time schedule of the target value of the ash charging amount so as to input a predetermined amount of the incinerated ash 1 into the furnace body 4. At that time, before cutting out the incinerated ash 1, the weight of the hopper 19 is measured by the load cell 20 to grasp the current value (W 1) of the weight of the hopper 19 before cutting out. Thereafter, the cutting device 21 is activated to start charging the incinerated ash 1. During the cutting, the load cell 20 measures the weight (Wi) of the hopper, and calculates the input amount of the incinerated ash 1. The input amount (Wn) of the incinerated ash 1 can be calculated by subtracting the hopper weight (Wi) being cut out from the hopper weight (W1) before the start of cutting.

  Such in-furnace temperature control and ash charge control are continuously performed, and when the in-furnace temperature reaches a predetermined temperature, the operation shifts to normal melting operation of the incinerated ash 1.

  As described above, in the present embodiment, when the electric resistance ash melting furnace is newly installed or when the refractory is renovated, the ash input amount is automatically controlled and the furnace temperature is automatically controlled. The rising pattern of the internal temperature can be optimized, and damage to the refractory 29 can be prevented. Moreover, since both the ash input amount and the furnace temperature can be automatically controlled, the operation at the time of start-up can be performed by a very small number of operators.

  In addition, although the said description demonstrated the electric resistance type ash melting furnace provided with three electrodes, it is not restricted to this, This invention is applied to the electric resistance type ash melting furnace provided with two or more electrodes. be able to.

  An embodiment when the electric resistance ash melting furnace shown in FIG. 1 is started up by performing the processing of the flowchart shown in FIG. 2 will be described below.

  In this embodiment, since the start-up was performed after the refractory was repaired, the time schedule of the temperature increase target value was set to a relatively gentle temperature increase pattern. Specifically, the temperature is increased from room temperature (25 ° C.) to 375 ° C. at a rate of 25 ° C./hr, held at 375 ° C. for 48 hours, and then increased from 375 ° C. to 600 ° C. at a rate of 25 ° C./hr again. When the temperature reached 0 ° C., the temperature rise was completed, and a pattern of shifting to steady operation was adopted.

  Further, the time schedule of the target value of the ash input is linearly increased to 200 kg / h when the temperature is raised from room temperature to 375 ° C., corresponding to the time schedule of the temperature increase target value, and 200 kg when the temperature is maintained at 375 ° C. / H was a constant value, and when the temperature was increased from 375 ° C. to 600 ° C., the pattern was linearly increased from 200 kg / h to 400 kg / h. Then, incineration ash having a thickness of about 150 mm was charged in advance into the furnace body, and energization was started.

  FIG. 3 is a diagram showing the transition of the furnace temperature, supply power, and incineration ash input during the start-up. In FIG. 3, the straight line a is the target temperature rise value, the curve b is the measured value of the furnace temperature, the straight line c is the target value of the supplied power calculated by the furnace temperature deviation, the curve d is the actual value of the supplied power, and the straight line e is The target value of incineration ash input, and the curve f is the actual measurement value of the incineration ash input. As shown in FIG. 3, the in-furnace temperature is controlled almost in line with the target temperature rise even when incineration ash is charged based on the time schedule without being excessive or insufficient. It has been found that the furnace temperature is automatically controlled appropriately by applying the invention.

It is a figure which shows an example of embodiment of this invention, and is a schematic systematic diagram of an electrical resistance type ash melting furnace. It is a figure which shows an example of embodiment of this invention, and is an example of the flowchart of the furnace temperature control method. It is a figure which shows transition of the furnace temperature when applying this invention, supply electric power, and the amount of ash inputs. It is a schematic system diagram of the conventional electric resistance type ash melting furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Incinerated ash 2 Molten slag 3 Molten metal 4 Furnace main body 5 Furnace lid 6a, 6b, 6c Electrode 7 Power transformer 8 Primary voltage regulator 9 Electrode support arm 10 Hydraulic cylinder 11 Ammeter 12 Voltmeter 13 Wattmeter 14 Temperature program setting Calculation unit 15 Electric power control panel 16 Thermometer 17 Input amount program setting device 18 Input amount control panel 19 Hopper 20 Load cell 21 Cutting device 22 Chute 23 Slag outlet 24 Slag outlet gate 25 Molten metal outlet 26 Molten metal outlet gate 27 Duct 28 Iron skin 29 Refractory

Claims (2)

A melting control method at the time of start-up of an electric resistance type ash melting furnace that energizes an electrode charged in the furnace and melts ash,
A step of setting the temperature increase target value of the furnace temperature in each elapsed time from the start of the ash melting furnace to the steady operation state as a time schedule of the temperature increase target value;
A step of setting a target amount of ash into the furnace at each elapsed time as a time schedule of the target amount of input, corresponding to the time schedule of the target temperature increase value ;
Measuring the temperature in the furnace;
Charging ash into the furnace based on the time schedule of the set input target value;
A step of controlling the power supplied to the electrode according to the deviation between the target temperature increase value of the set time schedule and the actual measured value of the in-furnace temperature ,
A melting control method at the time of starting up an electric resistance type ash melting furnace, characterized in that when the furnace temperature reaches a predetermined temperature, the operation shifts to a steady operation . A melting control device at the time of start-up of an electric resistance ash melting furnace that melts ash by energizing an electrode charged in the furnace,
A temperature setting means for setting a temperature increase target value of the furnace temperature in each elapsed time from the start of the ash melting furnace to a steady operation state as a time schedule of the temperature increase target value ;
Input amount setting means for setting the target amount of ash to be charged into the furnace at each elapsed time as the time schedule of the target amount of input corresponding to the time schedule of the temperature increase target value ;
A thermometer for measuring the temperature in the furnace;
A charging means for charging ash into the furnace based on the time schedule of the charging target value set by the charging amount setting means;
Supply power control means for controlling the power supplied to the electrode in accordance with the deviation between the target temperature increase value of the time schedule set by the temperature setting means and the measured value of the furnace temperature measured by the thermometer. ,
A melting control device at the time of starting up an electric resistance type ash melting furnace, characterized in that , when the temperature in the furnace reaches a predetermined temperature, it shifts to a steady operation .

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