JP4185667B2 - Operating method of plasma ash melting furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for operating a plasma ash melting furnace that melts incineration ash such as sewage sludge, municipal waste and industrial waste, and incineration ash discharged from an incinerator such as a commercial thermal power plant with high-temperature plasma. .
[0002]
[Prior art]
Conventionally, incineration ash (powder inorganic matter) such as sewage sludge, municipal waste, and industrial waste, for example, a plasma ash melting furnace as shown in FIG. The molten slag 52 and the molten metal 53 are taken out.
That is, in order to melt the incineration ash in the furnace main body 54 using such an ash melting furnace 51, for example, the incineration ash discharged from the waste incinerator is passed through various conveying means and supply means, etc. And the incinerated ash is melted by high-temperature plasma generated between the furnace bottom electrode 55 and the main electrode 56 that can be moved up and down. The molten slag 52 and the molten metal 53 generated in the furnace body 54 are discharged from the outlet 57 through the outlet 58 and guided to the slag pit and metal pit via a conveyor (not shown) for various uses. Will be served. A DC power supply 59 for generating a plasma arc is connected between the furnace bottom electrode 55 and the main electrode 56.
[0003]
By the way, the main electrode 56 is consumed by the operation of the ash melting furnace 1, so that when a plurality of electrode bars are connected to each other and the electrode bars near the tip of the main electrode 56 are consumed, In FIG. 3, the new electrode rods are successively connected. For this reason, the tip of each electrode rod is provided with a recess formed with an internal thread, and a seam (nipple part) 60 formed with an external thread is screwed into the recess. The electrode rods are coupled.
[0004]
[Problems to be solved by the invention]
However, in the operation method of the conventional ash melting furnace 51 described above, when the nipple portion 60 of the electrode rod constituting the main electrode 56 is close to the tip of the main electrode 56 as shown in FIG. The nipple portion 60 may be separated from the main electrode 56 due to its own weight or the like and fall into the molten slag 52 layer. Accordingly, the distance between the main electrode 56 and the molten slag 52 is widened and the arc length is suddenly increased. Therefore, the voltage of the DC power supply 59 is suddenly increased, and the power is cut off beyond the capability of the DC power supply 59. In addition, there was a problem that stable melting treatment could not be performed by causing arc breakage.
[0005]
The present invention has been made in view of such a situation, and an object of the present invention is to provide a plasma ash melting furnace capable of preventing a sudden increase in the voltage of a DC power supply device during operation and performing a stable melting process. It is to provide a driving method.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems of the prior art, in the present invention, incineration ash is put into a furnace main body provided with a vertically movable main electrode provided on a furnace ceiling wall, and the incineration ash is heated with a plasma arc. In the operation method of the plasma ash melting furnace that generates molten slag and molten metal by melting the main electrode, when the seam of each electrode rod constituting the main electrode is located near the tip of the main electrode The tip of the main electrode is lowered and inserted into the molten slag layer to forcibly consume the tip of the main electrode, and then the main electrode is raised and returned to its original position.
Moreover, in this invention, it is preferable that confirmation of the front-end | tip part position of the said main electrode is performed with the feed amount of the raising / lowering apparatus which raises / lowers this main electrode.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the operation method of the plasma ash melting furnace in the present invention will be described in detail based on the illustrated embodiment. Here, FIG. 1 is a schematic cross-sectional view showing a state in which the tip of the main electrode is inserted into the molten slag layer in the plasma ash melting furnace according to the embodiment of the present invention.
As shown in FIG. 1, the plasma ash melting furnace 1 of the present embodiment has a furnace body 2 having a refractory structure formed in a bottomed cylindrical shape, and the inside of the furnace body 2 is surrounded by a refractory 11. It is a furnace chamber 6. The furnace body 2 of the ash melting furnace 1 includes a main electrode 4 provided to hang down in the center of the furnace ceiling wall 3 and a furnace bottom electrode 7 provided in the center of the furnace bottom wall 5 so as to face the main electrode 4. And a DC power supply device 8 connected between the main electrode 4 and the furnace bottom electrode 7 and generating a plasma arc between these electrodes. The DC power supply 8 has a + connected to the furnace bottom electrode 7 side and a − connected to the main electrode 4 side.
[0008]
The main electrode 4 is supported by an elevating device 15 having clamping means so as to be movable up and down in order to move up and down in the furnace chamber 6. The elevating device 15 is attached to a support column movably by an electrode elevating hydraulic unit (not shown), and a rotary encoder (not shown) serving as a position detecting means for the main electrode 4 is attached to the upper portion of the elevating device 15. The confirmation of the position of the tip end portion is performed by detecting the feed amount of the lifting device 15 with the rotary encoder.
The main electrode 4 is configured to be supplied with nitrogen gas from a nitrogen gas generator (not shown), and is melted by heating the incinerated ash charged with high-temperature plasma. Therefore, as the main electrode 4, a cylindrical electrode having a passage through which nitrogen gas flows is formed.
[0009]
Further, since the main electrode 4 is a consumable item that is consumed as the ash melting furnace 1 is operated, a plurality of electrode rods 4a and 4b are connected to each other in the same manner as in the conventional example, and the vicinity of the tip of the main electrode 4 When the electrode rod is consumed, new electrode rods are successively connected in the upper position of the furnace body 2.
For this reason, concave portions 9a and 9b in which female threads are formed on the inner peripheral surface are provided on the tip surfaces of the electrode rods 4a and 4b, and cone-shaped seams (nipples) in which male screws are formed on the outer peripheral surfaces in the concave portions 9a and 9b. Part) 14 are screwed in, and the adjacent two upper and lower electrode rods 4a and 4b are connected by the nipple part 14.
[0010]
On the other hand, the outer peripheral wall of the furnace body 2 is covered with an iron skin 10, and the inner peripheral wall is formed of a refractory material 11 such as a refractory brick. Between them, a cooling jacket (not shown) for cooling the refractory material 11 is provided. It is arranged. Further, on the lower side surface of the furnace body 2, a tap outlet 17 for discharging the molten slag 12, the molten metal 13 and the exhaust gas 16 and a downwardly inclined tap bar 18 connected thereto are provided.
[0011]
While the molten slag 12 and the molten metal 13 are being melted, the molten metal 13 is laminated under the layer of the molten slag 12 due to the difference in specific gravity. It will be discharged by the overflow method that overflows through. Further, the molten metal 13 is discharged by extending and retracting the operating rod 21 of the hydraulic cylinder 20 to tilt the furnace body 2 around the rotation shaft 22 and lowering the tap hole 17 side. ing. Note that an ash charging port (not shown) for charging incineration ash such as waste into the furnace body 2 is provided on the upper side surface of the furnace body 2 opposite to the tap hole 17. A boundary line between the molten slag 12 and the gas atmosphere in the furnace chamber 6 is shown as a slag line L.
[0012]
Next, the operation method of the ash melting furnace 1 of this embodiment is demonstrated.
As shown in FIG. 1, incineration ash is charged into a furnace chamber 6 in the furnace body 2 of the ash melting furnace 1 from an ash charging port (not shown), and direct current is applied in a state where the furnace chamber 6 of the furnace body 2 is in a reducing atmosphere. A voltage is applied between the main electrode 4 and the furnace bottom electrode 7 by the power supply device 8. Then, a plasma arc is generated between the main electrode 4 and the furnace bottom electrode 7, and the atmosphere in the furnace chamber 6 becomes 1000 ° C or higher, and the incinerated ash is heated and melted.
The incinerated ash is laminated in the vertical direction as molten slag 12 and molten metal 13 that sinks under the molten slag 12. When a predetermined amount of molten slag 12 and molten metal 13 accumulates in the furnace bottom, as described above, the molten slag 12 overflows from the tap 17 and passes through the tap 18 and is discharged via a conveyor (not shown) to be melted. The metal 13 is discharged through the tap hole 17 and the tap bar 18 by tilting the furnace body 2.
[0013]
Further, in a state where a predetermined amount of molten slag 12 and molten metal 13 are accumulated on the furnace bottom in the furnace body 2, the nipple portions 14 of the electrode rods 4 a and 4 b constituting the main electrode 4 of the present embodiment are connected to the main electrode 4. 1, the main electrode 4 is lowered by the lifting device 15 and inserted into the molten slag 12 layer, as shown in FIG. Then, the electrode rod 4b and the nipple portion 14 at the tip of the main electrode 4 are melted by the molten slag 12 and are forcibly consumed. Whether or not the nipple portion 14 of the electrode rods 4a and 4b is located near the tip of the main electrode 4 is confirmed by detecting the feed amount of the elevating device 15 with a rotary encoder (not shown).
After the electrode rod 4b and the nipple portion 14 at the tip of the main electrode 4 are consumed, the main electrode 4 is lifted by the lifting device 15 and returned to the original position. A plasma arc is generated and a normal melting process is performed.
[0014]
In the operation method of the plasma ash melting furnace 1 according to the embodiment of the present invention, the nipple portion 14 of the electrode rods 4 a and 4 b constituting the main electrode 4 is near the tip of the main electrode 4 during the operation of the ash melting furnace 1. The main electrode 4 is lowered by the lifting device 15 and inserted into the molten slag 12 layer, and the electrode rod 4b and the nipple portion 14 at the tip of the main electrode 4 are forcibly consumed by the molten slag 12, After that, since the main electrode 4 is raised by the elevating device 15 and returned to the original position, the normal melting process is performed. Therefore, during the operation of the ash melting furnace 1, the nipple portion 14 or the like is provided as in the past. The arc length is suddenly increased by dropping, and the voltage of the DC power supply 8 is not suddenly increased to cause an arc break. This makes it possible to stably operate the ash melting furnace 1 and improve productivity. Can do. Moreover, since the position of the tip of the main electrode 4 is confirmed by detecting the feed amount of the lifting device 15 with an attached rotary encoder or the like, only the electrode rod 4b and the nipple portion 14 at the tip of the main electrode 4 are used. Can be consumed easily and reliably.
[0015]
As mentioned above, although embodiment of this invention was described, this invention is not limited to above-mentioned embodiment, Various changes are possible based on the technical idea of this invention. For example, in the above-described embodiment, the molten slag 12 is discharged by an overflow method, and the molten metal 13 is discharged by a tilting method that tilts the furnace body 2, but the operation method of the present invention is a method other than this. The present invention may be applied to a plasma ash melting furnace that discharges the molten slag 12 and the molten metal 13. Further, the position of the tip of the main electrode 4 may be confirmed by means other than the feed amount of the lifting device 15.
[0016]
【The invention's effect】
As described above, the operation method of the plasma ash melting furnace according to the present invention is to put incineration ash into a furnace main body provided with a vertically movable main electrode provided on the furnace ceiling wall, and heat the incineration ash with a plasma arc. When the seam of each electrode rod constituting the main electrode is located near the tip of the main electrode, the tip of the main electrode is lowered. By inserting the molten slag layer into the molten slag layer, the tip of the main electrode is forcibly consumed, and then the main electrode is raised and returned to its original position. During this process, it is possible to prevent the nipple part, etc., from falling and suddenly increasing the arc length and suddenly increasing the DC power supply voltage. Driveable and productive It is possible to achieve the above.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a state in which a tip portion of a main electrode is inserted into a molten slag layer in a plasma ash melting furnace according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a state in which a nipple portion of an electrode rod constituting a main electrode is located near a tip in a conventional plasma ash melting furnace.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plasma ash melting furnace 2 Furnace main body 3 Furnace ceiling wall 4 Main electrode 4a, 4b Electrode rod 5 Furnace bottom wall 7 Furnace bottom electrode 8 DC power supply device 9a, 9b Recess 12 Molten slag 13 Molten metal 14 Nipple part (seam)
15 Lifting device

Claims (2)

Plasma ash melting that generates molten slag and molten metal by charging incinerated ash into a furnace body equipped with a main electrode that can be moved up and down provided on the furnace ceiling wall, and heating the incinerated ash with a plasma arc In the operation method of the furnace, when the joint of each electrode rod constituting the main electrode is located near the tip of the main electrode, the tip of the main electrode is lowered and inserted into the molten slag layer. A method for operating a plasma ash melting furnace, wherein the tip of the main electrode is forcibly consumed, and then the main electrode is raised and returned to its original position. The method for operating a plasma ash melting furnace according to claim 1, wherein the position of the tip of the main electrode is confirmed by a feed amount of a lifting device that lifts and lowers the main electrode.

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