JP4667665B2 - Plasma ash melting furnace and operating method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma-type ash melting furnace capable of improving melting efficiency in a plasma-type ash melting furnace for recycling or reducing the amount of incineration ash obtained by melting slag by incineration ash such as waste, and its It relates to the driving method .
[0002]
[Prior art]
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.
[0003]
FIG. 4 shows a conventional plasma arc type ash melting furnace 1 among these ash melting furnaces, and the ash melting furnace 1 is provided with a furnace chamber 3 surrounded by a peripheral wall 14 of the melting furnace body 2. The ash melting furnace 1 is provided with a plasma device including a main electrode 4, a furnace bottom electrode 5, a DC power source 6, etc., and the main electrode 4 is suspended through the ceiling wall 7 of the melting furnace body 2. The inside of the furnace chamber 3 can be moved up and down by being supported by the elevating device 8. In the furnace bottom electrode 5, a furnace bottom electrode 5 is installed on a furnace bottom wall 9 immediately below the main electrode 4, and a DC power source 6 for plasma generation is connected between these electrodes 4 and 5. The melting furnace main body 2 has an outer wall covered with an iron skin 10, an inner wall 11 is formed of a refractory material such as brick, and an inlet 13 for incinerated ash 12 is disposed on the peripheral wall 14 of the melting furnace main body 2. 13 is provided with an outlet 17 that is an outlet for the molten slag 16, and an outlet 18 is connected to the outlet 17.
[0004]
With such a configuration, the incinerated ash 12 is introduced into the furnace chamber 3 of the ash melting furnace 1 from the inlet 13 of the incinerated ash onto the furnace bottom wall 9, and the furnace chamber 3 of the ash melting furnace 1 is made a reducing atmosphere. In this state, a voltage is applied between the electrodes 4 and 5 by the DC power source 6. Then, a plasma arc is generated between the electrodes 4 and 5, the incineration ash 12 is heated and melted to form a slag 16, and the metal component contained in the incineration ash is melted to form a molten metal 19 at the bottom of the furnace. Sink. When the molten slag 16 accumulates at the bottom of the furnace and reaches the height of the tap hole 17, the slag 16 overflows from the tap port 17, passes through the taphole 18, and is supplied to a mold (not shown). It is cooled with. On the other hand, if the melting furnace body 2 is tilted as shown in the figure, the molten metal 19 drives the cylinder 25 and tilts the melting furnace body 2 around the support shaft 26 as the rotation axis, so that the spout 17 The molten metal 19 is discharged from the furnace.
[0005]
[Problems to be solved by the invention]
However, in the conventional plasma ash melting furnace 1, when the inner diameter of the furnace chamber 3 is enlarged in order to increase the throughput, the temperature of the inner wall 11 near the tap outlet 17 of the furnace chamber 3 is incinerated ash 12. As shown in FIG. 5, the unmelted incinerated ash 12a floats on the surface of the slag 16 and is discharged from the outlet 17 to the outside of the furnace chamber 3 through the outlet 18 as it is. End up. The unmelted incinerated ash 12a may contain harmful metals, and it is necessary to discharge it out of the furnace chamber 3 after it is completely melted in order to ensure the quality of the slag. In such a case, it is conceivable to increase the output of the plasma electrodes 4 and 5, but the amount of electricity consumption increases.
The present invention has been made in view of such circumstances, in the case of rather large diameter of the furnace chamber in order to increase the ash amount of processing ash melting furnace, plasma ash melting capable of improving the melting efficiency The purpose is to provide a furnace.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a plasma ash melting furnace of the present invention includes a furnace body into which incinerated ash is charged, a main electrode disposed in the center of the furnace body of the furnace body, and a furnace of the furnace body A furnace bottom electrode disposed on the bottom wall, and a tap hole disposed on the peripheral wall of the furnace body, and applying a voltage between the main electrode and the furnace bottom electrode to generate a plasma arc. is generated, the ash melted by heating and slag, in the produced plasma ash melting furnace so as to discharge into the furnace outside from the tapping port as a molten slag, approximately straight line connecting the said main electrode and tapping port A furnace chamber auxiliary electrode for heating the surface of the molten slag is arranged in the furnace chamber on the intermediate point of the straight line or closer to the outlet than the intermediate point , and the furnace chamber auxiliary electrode is A voltage is applied between the furnace bottom electrode and a plasma arc is generated, and the plasma is generated together with the main electrode. With ash heated and melted to be operated in order to slugging, the the main electrode can be separately adjusted power. Note that “substantially on a straight line” includes a range where there is a slight deviation from that on the straight line, and the slight deviation is a range in which the effect of the present invention can be exhibited.
[0007]
Further, the present invention provides a method for operating the plasma ash melting furnace in which a voltage is applied between the main electrode and the furnace bottom electrode, and between the furnace chamber auxiliary electrode and the furnace bottom electrode, respectively. When generating the plasma arc to heat and melt the incinerated ash to make slag, the outlet is monitored by an infrared camera through an infrared transmission window provided on the furnace wall of the furnace body, and the infrared camera is not yet connected to the infrared camera. In a normal operation state where the presence of molten incineration ash is not observed, the power of the furnace chamber auxiliary electrode is set small, and when the presence of unmelted incinerated ash is observed in the infrared camera, the furnace chamber auxiliary electrode This is because the operation method to increase the electric power of is adopted.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plasma ash melting furnace according to an embodiment of the present invention will be described with reference to the drawings. In addition, about the member of the same name as a prior art example, the same code | symbol is attached | subjected and demonstrated. FIG. 1 shows a plasma arc type ash melting furnace 1 according to the present invention. The ash melting furnace 1 is provided with a furnace chamber 3 surrounded by a peripheral wall 14, and the peripheral wall 14 is formed of a heat-resistant material such as a heat-resistant brick. Yes. Further, the ash melting furnace 1 is provided with a main electrode 4 disposed on the furnace chamber 3 side and a furnace bottom electrode 5 disposed on the furnace bottom wall 9 of the furnace chamber 3, and these plasma electrodes 4, 5 are provided. Is arranged on the central axis of the furnace chamber 3 having a circular horizontal section.
[0009]
One main electrode 4 penetrates the ceiling wall 7 of the melting furnace main body 2 and is suspended and arranged so as to move up and down in the furnace chamber 3 by being supported by the lifting device 8. ing. 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. The other furnace bottom electrode 5 is disposed immediately below the main electrode 4 and is disposed so as to face the tip portion thereof. A DC power source 6 for generating plasma is connected between the plasma electrodes 4 and 5. The direct current power source 6 has a + connected to the furnace bottom electrode 5 side and a − connected to the main electrode 4 side. On the lower wall portion of the melting furnace main body 2, a tap hole 17 that is a discharge port for the molten slag 16 is disposed, and a tap bar 18 is connected to the tap port 17. The spout 17 and the spout 18 are made of a refractory material.
[0010]
On the ceiling wall 7 of the ash melting furnace main body 2, an auxiliary electrode 20 that is a furnace chamber electrode is provided separately from the main electrode 4. The cylindrical auxiliary electrode 20 is suspended from the ceiling wall 7 into the furnace chamber 3 and can be moved up and down by an elevating device 21. As shown in FIG. 2, in the present embodiment, the auxiliary electrode 20 is arranged such that the axis A of the auxiliary electrode 20 is the center B of the axis O of the main electrode 4 and the width direction of the opening of the tap opening 17. Is arranged on the line connecting the main electrode 4 and the opening 17 of the main electrode 4 (OC = CB = L) C or at a position closer to the outlet 17 side than the intermediate part C (between CB) is doing. Further, the main electrode 4 and the auxiliary electrode 20 having the same diameter can be used, and this makes it possible to use a common electrode extension device, which is convenient. However, the main electrode 4 and the auxiliary electrode 20 are not necessarily made common, and for example, if the diameter of the auxiliary electrode 20 is reduced, there is an advantage that the space in the furnace chamber becomes wider.
[0011]
A viewing window 22 is provided on the wall of the melting furnace body 2 at a position where the flow of the molten slag 16 at the spout 17 can be observed, and an infrared camera 23 is disposed in the vicinity of the viewing window 22. Since this infrared camera 23 is for observing the unmelted incinerated ash 12 a at the tap outlet 17, the flow of the molten slag 16 on the front side (upstream side) of the tap outlet 17 and the molten slag 16 at the taphole 18. You may provide in the site | part which can observe the flow of this. An image taken by the infrared camera 23 can be observed through a monitor connected thereto. The peripheral wall 14 of the melting furnace body 2 is provided with a charging port 13 for charging the incinerated ash 12 into the furnace chamber 3, and the charging port 13 communicates with an ash supply hopper (not shown). The ash melting furnace 1 is provided with a number of other equipment such as a control device for controlling plasma and a cooling device for cooling the peripheral wall 14 (not shown). .
[0012]
Next, the effect | action of embodiment in the plasma ash melting furnace of this invention is demonstrated. As shown in FIG. 1, incineration ash 12 is introduced into the furnace chamber 3 of the ash melting furnace 1 from the inlet 13 of the incineration ash 12 onto the furnace bottom wall, and the furnace chamber 3 of the ash melting furnace 1 is brought into a reducing atmosphere. In this state, a voltage is applied between the furnace chamber side electrodes 4, 20 and the furnace bottom electrode 5 by the DC power source 6. At this time, the output amount of the auxiliary electrode 20 is kept small. In this way, a plasma arc is generated between these electrodes, the atmosphere in the furnace chamber 3 becomes 1000 ° C. or higher, and the incineration ash 12 is heated and melted to form molten slag 16, which is contained in the incineration ash 12. The molten metal component also melts to become molten metal 19 and sinks to the furnace bottom. When the molten slag 16 as a supernatant accumulates at the bottom of the furnace and reaches the height of the tap hole 17, the slag 16 overflows from the tap port 17, passes through the tap 18 and is discharged out of the furnace chamber. Since the main electrode 4 and the auxiliary electrode 20 are consumed during the operation of the ash melting furnace 1, the elevating devices 8 are arranged so that the tips of the electrodes 4, 20 are located at a predetermined height from the surface of the molten slag 16. , 21 is used to adjust the height by the consumed amount.
[0013]
During the operation of the ash melting furnace 1, the infrared camera 23 shown in FIG. The infrared camera 23 captures the flow of the molten slag 16 at the tap outlet 17 and can observe whether or not the unmelted incinerated ash 12a flows out of the furnace chamber. On the other hand, when the diameter of the furnace chamber 3 is designed to be large in order to increase the throughput of the melting furnace body 2, the center side of the furnace chamber 3 is maintained at a high temperature, but on the inner wall 11 side. The unmelted incinerated ash 12a in the vicinity of the located wall surface may have a temperature equal to or lower than the melting point, and the unmelted incinerated ash 12a may flow out from the tap outlet 17. In such a case, the presence of the unmelted incinerated ash 12a is monitored by the infrared camera 23, and the electric energy on the auxiliary electrode side 20 and 5 is increased before it flows out of the tap outlet 17. Thereby, the temperature of the unmelted incinerated ash 12a located on the inner wall 11 in the vicinity of the tap outlet 17 is increased, and the unmelted incinerated ash 12 can be melted and discharged. When there is no possibility that the unmelted incineration ash 12a flows out, the output amount of the auxiliary electrode 20 is adjusted to be small. As an operation method of the ash melting furnace 1, the output amounts of the main electrode 4 and the auxiliary electrode 20 may be alternately increased or decreased while observing the output state of the molten slag 16. Furthermore, the outputs of both the main electrode 4 and the auxiliary electrode 20 may be simultaneously increased or decreased. Any of these operating methods can prevent the unmelted incinerated ash 12a from flowing out of the furnace chamber 3.
[0014]
FIG. 3 is a diagram showing another operation method of the plasma ash melting furnace 1. While the melting furnace main body 2 is in operation, the tip of one main electrode 4 is inserted into the molten slag 16 layer, and the other auxiliary electrode 20 is spaced a predetermined distance from the surface of the molten slag 16 so that the ash melting furnace main body 1 is Operate. Then, the main electrode 4 disposed in the center of the furnace chamber 3 exhibits a stirring effect so that the molten slag 16 layer is diffused, and the temperature of the molten slag 16 can be made uniform. On the other hand, the auxiliary electrode 20 raises the surface temperature of the molten slag 16 and melts the unmelted incinerated ash 12a.
[0015]
As described above, in the present embodiment, since one electrode is composed of the main electrode 4 and the auxiliary electrode 20, when the unmelted incineration ash 12a flows out of the furnace chamber 3, The output of the auxiliary electrode 20 can be increased to melt the unmelted incinerated ash 12a. In addition, when the infrared camera 23 is used to observe the vicinity of the upstream side of the tap outlet 17 in the furnace chamber 3, the presence of the unmelted incineration ash 12 a can be known in advance, and the unmelted incineration ash is output from the tap outlet 17. It is possible to immediately prevent 12a from flowing out.
[0016]
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.
[0017]
【The invention's effect】
As described above, according to the plasma ash melting furnace of the present invention, the furnace body into which the incinerated ash is charged, the main electrode disposed in the center of the furnace chamber of the furnace body, and the furnace bottom of the furnace body Plasma-type ash melting provided with a furnace bottom electrode disposed on the wall, and an outlet that discharges molten slag formed by melting the incinerated ash heated by the main electrode and furnace bottom electrode to the outside of the furnace chamber in the furnace, in the almost straight line connecting the said main electrode and tapping port, the furnace chamber of the tapping port nearer the midpoint or intermediate points of the straight line, the furnace chamber for heating the molten slag surface Since the auxiliary electrode is disposed, the outflow of unmelted incineration ash from the tap outlet can be suppressed by adjusting the power of the auxiliary electrode in the furnace chamber .
[0018]
Further, as an operation method of the plasma ash melting furnace, the outlet is monitored with an infrared camera through an infrared transmission window provided on the furnace wall of the furnace body, and the presence of unmelted incinerated ash is not observed in the infrared camera. In the normal operation state, the electric power of the auxiliary electrode in the furnace chamber is set to be small, and when the presence of unmelted incineration ash is observed in the infrared camera, the electric power of the auxiliary electrode in the furnace chamber is increased and unmelted. Since the operation method of melting the incinerated ash was adopted, it was possible to prevent the unfused incinerated ash from flowing out of the furnace chamber.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a plasma arc ash melting furnace of the present invention.
FIG. 2 is a schematic cross-sectional view of the plasma ash melting furnace of FIG.
3 is a schematic cross-sectional view showing a state in which a tip portion of a main electrode of the plasma arc ash melting furnace of FIG. 1 is inserted into a molten slag.
FIG. 4 is a schematic longitudinal sectional view of a conventional plasma arc ash melting furnace.
FIG. 5 is a schematic cross-sectional view of a conventional plasma arc ash melting furnace.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plasma arc type ash melting furnace 2 Melting furnace main body 3 Furnace room 4 Main electrode 5 Furnace bottom electrode 6 DC power source 7 Ceiling wall 8, 21 Lifting device 10 Iron skin 11 Inner wall 12, 12a Incinerated ash 13 Inlet 14 Surrounding wall 16 Melting slag 17 Outlet 18 Outlet 19 Molten Metal 20 Auxiliary Electrode 22 Viewing Window 23 Infrared Camera

Claims (2)

A furnace body into which incinerated ash is charged, a main electrode disposed in the center of the furnace body of the furnace body, a furnace bottom electrode disposed on a furnace bottom wall of the furnace body, and a peripheral wall portion of the furnace body and a is a tapping opening arranged in, the main voltage between the electrode and the furnace bottom electrode is applied to generate plasma arc, the ash melted by heating and slagging, leaving the as molten slag In a plasma type ash melting furnace configured to discharge from the throat to the outside of the furnace chamber, the ash melting furnace is substantially on a straight line connecting the main electrode and the throat, and is located at an intermediate point of the straight line or at a position higher than the intermediate point. A furnace chamber auxiliary electrode for heating the surface of the molten slag is disposed in the furnace chamber near the mouth, and the furnace chamber auxiliary electrode applies a voltage between the furnace bottom electrode and generates a plasma arc. The incinerated ash can be heated and melted together with the main electrode to operate as slag. The plasma ash melting furnace, wherein the the main electrode can be separately adjusted power. The operation method of the plasma type ash melting furnace according to claim 1 , wherein a voltage is respectively applied between the main electrode and the furnace bottom electrode and between the furnace chamber auxiliary electrode and the furnace bottom electrode. When the incinerated ash is heated and melted to form slag, the outlet is monitored by an infrared camera through an infrared transmission window provided on the furnace wall of the furnace body, and the infrared camera is connected to the infrared camera. In a normal operation state where the presence of unmelted incineration ash is not observed, the power of the auxiliary electrode in the furnace chamber is set small, and if the presence of unmelted incineration ash is observed in the infrared camera, the auxiliary in the furnace chamber the method of operating a plasma ash melting furnace, characterized in that to increase the power of the electrode.

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