JP2006132926A - Operation method for plasma type ash melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method for a plasma type ash melting furnace capable of preventing plasma arc from being eliminated when molten metal accumulated at the bottom part of the ash melting furnace is discharged while the ash melting furnace is operated. <P>SOLUTION: In this operation method for the plasma type ash melting furnace generating molten slag 23 by throwing incineration ash in the furnace chamber 6 of a furnace body 2 and heating and melting the incineration ash by the plasma arc, an arc length is obtained by using the level height of the slag and the height of the lower end part of a main electrode 4 as viewed by an infrared camera 17, and a length between the lower end part of the main electrode 4 and the level of the molten slag is adjusted to a prescribed value or within a prescribed range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a plasma-type ash melting furnace for recycling or reducing the amount of incineration ash obtained by melting slag by incineration ash such as garbage, and operating the ash furnace main body according to the amount of incineration ash. The present invention relates to a method for operating a plasma ash melting furnace.

  The ash melting furnace is intended for effective use of refuse incineration ash, and the incineration ash melted by the ash melting furnace is made harmless by separating it into low boiling point volatilized materials and slag of metals and other components. , We are trying to recycle it. The need for incinerator ash melting furnaces is increasing. In these ash melting furnaces, ash is produced using electricity as a heat source, such as burner ash melting furnaces that use heavy oil as fuel to melt incinerated ash, electric resistance ash melting furnaces, and plasma ash melting furnaces. Those that melt are known.

FIG. 4 shows a conventional plasma arc ash melting furnace 51, which is provided with a furnace chamber 56 surrounded by a melting furnace body 52. The ash melting furnace 51 is provided with a plasma device including a main electrode 54, a furnace bottom electrode 57, a DC power source 58, and the like, and the main electrode 54 is disposed through the ceiling wall 53 of the melting furnace body 52. In addition, the furnace chamber 56 can be moved up and down by being supported by the lifting device 65. At the lower end of the main electrode 54, a furnace bottom electrode 57 is installed on the furnace bottom wall 55 facing the front end thereof, and a DC power source 58 for plasma generation is connected between these electrodes 54, 57.
The melting furnace main body 52 has an outer wall covered with an iron skin 60, an inner wall 61 is formed of a refractory material such as brick, and a spout 68 serving as an outlet for the molten slag 63 is arranged on the peripheral wall of the melting furnace main body 52. The output port 68 is connected to the output port 69. A mold 71 placed on the feed conveyor 70 is disposed below the tip of the feed 69.

With such a configuration, incinerator ash is introduced into the furnace chamber 56 of the ash melting furnace 51 from the incinerator ash inlet (not shown) on the furnace bottom wall, and the furnace chamber 56 of the ash melting furnace 51 is in a reducing atmosphere. Thus, a voltage is applied between the electrodes 54 and 57 by the DC power source 58. Then, a plasma arc is generated between the electrodes 54 and 57, the incineration ash is heated and melted to form the slag 63, and the metal components contained in the incineration ash are melted to form the molten metal 64 and sink to the furnace bottom. . When the molten slag 63 accumulates in the furnace bottom and reaches the height of the outlet port 68, the slag 63 overflows from the outlet port 68 and is supplied to the mold 71 through the outlet 69, and the slag 63 is cooled. The On the other hand, if the melting furnace body 51 is tilted, the molten metal 64 tilts the melting furnace body and discharges the molten metal from the spout (see, for example, Patent Document 1). If it is a thing, a hole is made in the furnace wall of the melting furnace body, and the molten metal is discharged out of the furnace.
JP 11-351544 A

Since the main electrode of the plasma electrode is consumed during the operation of the ash melting furnace, it is necessary to lower the main electrode by using the lifting device by the amount consumed. However, even if an attempt is made to measure the arc length of the plasma arc in the furnace chamber with a visible camera or the like, the arc length of the plasma arc cannot be grasped during operation because it is blocked by dust floating in the furnace.
Therefore, the amount of electrode consumption will be judged based on experience values, but this has problems with individual differences and accuracy, and if the arc length becomes long after continuous operation for a long time, the temperature of the ceiling refractory becomes higher and the slag increases. The heat input efficiency may be reduced. On the other hand, when the main electrode sinks below the slag surface, the liquid surface becomes low temperature, and slag outflow failure occurs.

If the amount of incineration ash charged into the furnace chamber of the ash melting furnace is different, it is necessary to adjust the output of the plasma electrode accordingly. When the power becomes excessive due to the above, the life of the refractory material forming the furnace chamber is lowered due to high temperature operation. On the other hand, when the power is insufficient, the operation becomes low temperature, and the slag closes the tap and the ash melting furnace becomes inoperable.
On the other hand, the molten metal having a specific gravity larger than that of the molten slag precipitates under the molten slag layer, and when the operation of the ash melting furnace is continued for a long time, the molten metal layer becomes thick and the ratio of the molten slag layer decreases. When the slag layer becomes thin, the power supply voltage fluctuates, causing troubles in operation. Therefore, when a molten metal precipitation layer accumulates at the bottom of the ash melting furnace, it is discharged outside the furnace chamber. Conventionally, when discharging molten metal from the furnace chamber while discharging the ash melting furnace (turning on the plasma arc), while making the voltage value between the main electrode and the furnace bottom electrode substantially constant, I was out of metal. However, since the fluctuation range of the voltage value is large, it is difficult to determine whether the voltage value is rising or not, and the plasma arc may be cut off by mistake.

  The present invention has been made in view of such circumstances, and in order to melt the incineration ash to form slag, the constant voltage, that is, the plasma electrode is constant voltage (constant arc length) so that there is no overpower or power shortage. If the melting temperature is low with reference to the voltage without changing the temperature of each part, the slag melting temperature is increased by flowing a large amount of current through the plasma electrode, and if the melting temperature is high, the current is decreased to the plasma electrode. The slag melting temperature can be lowered by flowing, and furthermore, when discharging molten metal etc. accumulated at the bottom of the ash melting furnace while operating the ash melting furnace, a plasma type in which the plasma arc does not disappear It aims at providing the operating method of an ash melting furnace.

  In order to achieve the above object, the present invention operates a plasma ash melting furnace in which incinerated ash is charged into a furnace chamber of a furnace body, and the incinerated ash is heated and melted by a plasma arc to generate molten slag. In the method, the arc length is obtained from the liquid surface height of the slag and the height of the lower end portion of the main electrode viewed with an infrared camera, and the length from the lower end portion of the main electrode to the molten slag surface is a constant value or a predetermined range. Adjusted to within.

As described above, according to the present invention, since the arc length of the plasma arc is analyzed through the infrared camera, the temperature of each part in the furnace is kept constant by setting the arc length to a certain length. be able to. As a result, the arc length does not fluctuate, so that the temperature of the molten slag in the furnace chamber is not increased more than necessary, the life of the refractory material on the inner wall is lengthened, and unnecessary power is prevented. The temperature is low and the port is not blocked.
In addition, since the arc length is observed using an infrared camera, the distance between the lower end of the main electrode and the molten slag surface can be kept constant during the discharge of molten metal, thereby preventing the disappearance of the plasma arc. be able to.

Hereinafter, the operation method of the ash melting furnace by embodiment of this invention is demonstrated, referring drawings.
FIG. 1 shows a tilting plasma arc ash melting furnace 1 according to the present invention. The ash melting furnace 1 is provided with a furnace chamber 6 surrounded by an inner wall 11, and the inner wall 11 is formed of a heat-resistant material such as a heat-resistant brick. Has been. Further, the ash melting furnace 1 includes a plasma apparatus including a main electrode 4 disposed on the furnace chamber 6 side, a furnace bottom electrode 7 disposed on the furnace bottom wall 5 of the furnace chamber 6, a DC power source 8, and the like. Is provided. The main electrode 4 is arranged so as to hang down through the ceiling wall 3 of the melting furnace main body 2 and is configured to be able to move up and down in the furnace chamber 6 by being supported by the lifting device 15. The main electrode 4 is made of metal or graphite, and has a cylindrical shape in which a passage for generating a plasma gas is formed. At the lower end of the main electrode 4, a furnace bottom electrode 7 is installed on the furnace bottom wall 5 facing the tip, and a DC power source 8 for plasma generation is connected between these electrodes 4, 7. The DC power source 8 is connected to + on the furnace bottom electrode 7 side and connected to-on the main electrode 4 side.

A viewing window 12 is provided in the wall portion of the melting furnace body 2, a visible camera 13 is disposed in the vicinity of the viewing window 12, and a scale for measuring the height position of the inner wall 11 is provided on the inner wall 11. It is displayed. The visible camera 13 can measure the liquid level of the slag by looking at the scale.
FIG. 2 is a cross-sectional view of the melting furnace main body 2 of FIG. 1 viewed from another angle. As shown in FIG. 2, the melting furnace main body 2 is provided with a viewing window 16 penetrating the inner wall 11 and the iron skin 10, and an infrared camera 17 is disposed outside the viewing window 16. The wavelength of the infrared camera 17 can be 3 μm or more, preferably 8 μm or more. The infrared camera 17 is arranged toward the tip of the main electrode 4 and can observe the arc length of the plasma arc through the observation window 16 through a monitor or the like.

A hydraulic cylinder 25 is installed at one end of the furnace bottom 5 of the melting furnace main body 2, and the distal end portion of the telescopic rod 26 of the cylinder 25 is pivotally supported by the furnace bottom 5. A rotating shaft 27 serving as a central axis for tilting the melting furnace main body 2 is provided on the other end side of the furnace bottom 5 so as to face the mounting portion of the cylinder 25. In the melting furnace main body 2, the one end side of the melting furnace main body 2 is lifted by extending the telescopic rod 26 of the hydraulic cylinder 25, and as a result, the outlet port 19 side on the other end side can be lowered.
A cooling jacket (not shown) is disposed around the inner wall 11 of the melting furnace body 2, and a spout 18 serving as a discharge port for the melting slag 23 is disposed on the lower wall portion of the melting furnace body 2. An output 19 is connected to the shed 18. The tap opening 18 and the tap bar 19 are made of a refractory material. A mold 22 placed on the feed conveyor 21 is disposed immediately below the tip of the feed 19. The mold 22 collects the molten slag 23 that flows down from the tap 19.
The ash melting furnace 1 is provided with a number of other equipment such as an ash charging hopper (not shown), a control device for controlling plasma, etc., but detailed description thereof is omitted. To do.

Next, the operation of the embodiment of the present invention will be described.
As shown in FIG. 1, incineration ash is introduced into the furnace chamber 6 of the ash melting furnace 1 from a charging port (not shown) of the incineration ash onto the furnace bottom wall, and the furnace room 6 of the ash melting furnace 1 is made a reducing atmosphere. In this state, a voltage is applied between the electrodes 4 and 7 by the DC power supply 8. Then, a plasma arc is generated between the electrodes 4 and 7, the furnace chamber 6 has an atmosphere of 1000 ° C. or higher, and the incineration ash is melted. The incinerated ash is melted to form slag 23, and the metal component contained in the incinerated ash is melted to form molten metal 24 and sinks to the furnace bottom. When the molten slag 23 as a supernatant accumulates at the bottom of the furnace and reaches the height of the tap 18, the slag 23 overflows from the tap 18, passes through the tap 19 and is disposed on the tap conveyor 21. Then, the slag 23 is air-cooled.

During operation of the ash melting furnace 1, the infrared camera 17 shown in FIG. 2 captures the tip of the main electrode 4 of the plasma electrode. The infrared camera 17 captures the shape of the plasma arc, and the shape of the plasma arc can be viewed on a monitor.
Therefore, the video imaged by the infrared camera 17 is projected on the monitor, the arc shape is image-analyzed, and the arc length is derived. During melting of the incineration ash, the position of the main electrode 4 (the height on the slag surface) is constantly maintained by moving the main electrode 4 up and down by the lifting device so that the length of the arc length is constantly maintained. ), And this makes the temperature of each part constant. This may be automated by a control device or the like, or may be manually performed by an operator manually by a control unit of the plasma apparatus. Thus, by making the height on the slag surface of the main electrode 4 constant, the arc length of the plasma arc can be maintained at a constant length.

  In addition, when the slag 23 comes to be discharged | emitted from the tap outlet 18, since the liquid level height of the slag 23 becomes the height of the tap outlet 18, the liquid level height of the slag 23 is known, The height of the lower end of the electrode 4 can be viewed with the infrared camera 17, and the arc length can be accurately determined without analyzing the shape of the plasma arc by determining the mounting angle of the infrared camera 17 and the position of the main electrode 4. Can be sought.

Thus, by making the distance between the main electrode 4 and the slag 23 surface, that is, the arc length of the plasma arc constant, the furnace temperature distribution can be made constant, and the melting temperature of the slag 23 is lower than the set value. If so, the temperature of the molten slag 23 is increased, the current amount of the plasma electrodes 4 and 7 is increased through a control device or the like to increase the amount of heat generated by the plasma electrodes 4 and 7, and the incineration ash or molten slag is increased. 23 can be heated.
If it is determined that the melting temperature of the slag 23 is higher than the set value, the amount of heat generated can be reduced by reducing the current amount of the plasma electrode via a control device or the like, and the melting temperature of the molten slag 23 can be lowered. .

In the present embodiment, when the molten metal 24 has accumulated in the melting furnace body 2, the melting furnace body 2 itself is tilted as described above, and the molten metal 24 is discharged out of the furnace chamber 6. That is, as shown in FIG. 3, by extending the rod 26 of the cylinder 25 upward, the position of the melting furnace body 2 on the cylinder 25 side is increased, and on the contrary, the position of the tap hole 18 is decreased, The metal 24 is discharged out of the furnace chamber 6.
At this time, when the molten metal 24 is discharged from the melting furnace body 2, as the melting furnace body 2 tilts, the molten metal 24 is discharged and the distance between the lower end of the main electrode 4 and the surface of the molten slag 23 increases. There is a possibility that the plasma arc may disappear due to the length of the arc becoming longer. In the present embodiment, since the arc length of the plasma arc is observed by the infrared camera 17 shown in FIG. 2, the main electrode 4 is moved down as the tilting amount of the melting furnace body 2 increases. The distance between the lower end of 4 and the surface of the molten slag 23 can be kept constant.

When the discharge operation of the molten metal 24 is completed, the melting furnace body 2 is returned to the normal upright state. That is, by contracting the rod 26 of the cylinder 25, the position of the melting furnace body 2 on the cylinder 25 side is lowered, and the height of the spout 18 is restored.
At this time, the distance between the lower end of the main electrode 4 and the surface of the molten slag 23 varies as the melting furnace body 2 approaches an upright state, but the arc length of the plasma arc is observed by the infrared camera 17. Thus, as the tilting amount of the melting furnace body 2 decreases, the height of the main electrode 4 can be adjusted, and the distance between the lower end of the main electrode 4 and the surface of the molten slag 23 can be maintained constant. Therefore, disappearance of the plasma arc can be prevented.

As described above, in the present embodiment, the arc length of the plasma arc is measured by the infrared camera 17, and the position of the main electrode 4 and thereby the temperature of each part can be made constant. If there is a change in the slag temperature from that state, the heating value of the incineration ash can be increased or decreased according to the state of the furnace chamber 6 by changing the current value of the plasma electrodes 4 and 7. As a result, the temperature of the molten slag 23 in the furnace chamber 6 is not increased more than necessary, and the life of the refractory material on the inner wall 11 can be extended and wasteful power can be prevented.
Further, the molten metal 24 can be discharged while the plasma arc is ignited when the molten metal 24 is discharged, and the trouble of reigniting the plasma arc can be omitted.

The embodiment of the present invention has been described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.
For example, in the present embodiment, the molten metal 24 is discharged by inclining the melting furnace body 2 to discharge the molten metal 24. However, the molten metal 24 is discharged by making a discharge port in the furnace wall. Also in the case of the mud gun method, the arc length of the plasma arc can be observed using the infrared camera 17 and the main electrode 4 can be lowered according to the discharge amount of the molten metal 24.
Further, the present invention can be applied to an AC arc furnace or a twin torch.

It is a schematic sectional drawing which passes along the cross section of the tap outlet of the plasma arc type ash melting furnace of this invention. It is the schematic sectional drawing which looked at the ash melting furnace of Drawing 1 from another angle. It is a schematic sectional drawing which shows the state which inclined the plasma arc type ash melting furnace of FIG. It is a schematic sectional drawing which passes along the cross section of the tap outlet of the conventional plasma arc type ash melting furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma arc type ash melting furnace 2 Melting furnace main body 3 Ceiling wall 4 Main electrode 5 Furnace bottom wall 6 Furnace room 7 Furnace bottom electrode 8 DC power supply 10 Iron skin 11 Inner wall 12, 16 Viewing window 13 Visible camera 15 Lifting device 17 Infrared camera 18 Unloading port 19 Unloading 21 Unloading conveyor 22 Mold 23 Molten slag 24 Molten metal 25 Cylinder 26 Rod 27 Rotating shaft

Claims (1)

  In a method of operating a plasma ash melting furnace in which incinerated ash is put into a furnace chamber of a furnace body and the incinerated ash is heated and melted by a plasma arc to generate molten slag, the liquid level of the slag and an infrared camera The arc length is obtained from the height of the lower end portion of the main electrode viewed in Step 1, and the length from the lower end portion of the main electrode to the molten slag surface is adjusted to a constant value or within a predetermined range. , Operation method of plasma ash melting furnace.

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