JP3039590B2 - Plasma melting furnace and operation method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma melting furnace for burning and melting waste incineration ash with a plasma arc and a method of operating the same.

[0002]

2. Description of the Related Art In recent years, global environmental problems and resource recycling problems have attracted attention. In particular, municipal solid waste and industrial waste are increasing year by year, and it is becoming difficult to secure landfill sites for landfills, especially in metropolitan areas. Therefore, it is common to incinerate municipal solid waste and industrial waste to reduce the volume and landfill.

[0003] However, these municipal solid wastes and industrial wastes often contain various harmful substances and metals, and ash and incombustibles after incineration (hereinafter referred to as incineration ash).
In these, these harmful substances and metals remain. Therefore, there is a problem that groundwater is polluted when incinerated ash is landfilled. Also, incinerated ash has a low specific gravity and requires a large volume of landfill land, and the ground after landfill is also weak, which often makes it difficult to use the site.

[0004] Therefore, these incinerated ash are being melted by plasma, and then cooled and solidified. In the case of heavy metals such as chrome, the molten and solidified slag is contained in the slag and does not elute in water, so there is no problem with groundwater contamination after landfill disposal. For this reason, it can be used for construction aggregates, roadbed materials, etc., eliminating the need for landfill sites and recycling resources.

[0005] As a plasma melting furnace for melting incineration ash with plasma, for example, the one described in Japanese Patent Application Laid-Open No. 3-55411 is known. This plasma melting furnace includes a melting furnace having an incineration ash supply hole and a slag discharge hole, in which a slag bath is formed on a hearth, and a plasma torch for generating a plasma arc in the slag bath. It is. The incineration ash supplied from the incineration ash supply hole is incinerated and melted by the plasma arc to form a slag bath in the furnace, and the slag overflowing from the slag bath is continuously discharged from the slag discharge hole and solidified by cooling. In a conventional plasma melting furnace used for metal melting, a plasma torch is located at the center of a cylindrical furnace, and some of them are rotatable around the furnace center as shown in British Patent 1390351/3. In addition, Tohoku University Mineral Refinery Research Report Vol.41, No.2, p170-1
As shown in 71 (1985), in a plasma melting furnace for direct reduction of chromite ore, there is one in which a plasma torch is rotated while being inclined, and is uniformly heated over a wide area.

In the above-described plasma melting furnace, the incinerated ash to be melted is a fine particle having a particle diameter of several microns. In general, a negative pressure operation is performed by an inducing fan from the incineration ash supply hole side to the slag discharge hole so as not to leak to the outside atmosphere.

[0007]

However, in the negative pressure operation by the above-mentioned inducing fan, the incineration ash of the fine particles follows the flow in the furnace from the incineration ash supply hole by the inducing fan to the slag discharge hole, and the slag of the hearth is formed. There is a problem that it may be released from the discharge hole to the outside of the furnace before landing in the bath. In this case, it goes without saying that the efficiency of converting the incinerated ash into slag decreases, but if it accumulates in the duct from the discharge hole outside the furnace, it may cause troubles in the equipment.

The present invention has been made in view of such problems, and it is an object of the present invention to ensure that incinerated ash is reliably deposited on a slag bath of a hearth, and is efficiently melted and converted into slag. A plasma melting furnace and an operation method thereof are provided.

[0009]

In order to achieve the above object, the present invention provides a plasma melting furnace and a method of operating the same, wherein a gas nozzle for blowing a gas such as air toward a slag bath of a hearth is provided in an incineration ash supply hole of the melting furnace. When the plasma torch is tilted by the driving device, the melting furnace is provided with a driving device that changes the blowing angle of the gas nozzle in conjunction with the driving device of the plasma torch, and a gas such as air is supplied from the incineration ash supply hole. It is always operated by blowing into the slag bath located at the irradiation destination of the plasma torch.

[0010]

According to the above-mentioned means, the flow of gas such as air blown from the incineration ash supply hole toward the slag bath located at the irradiation destination of the plasma torch restrains the incineration ash, and the gas flows from the incineration ash supply hole by the inducing fan. Along with the flow in the furnace to the slag discharge hole, it is prevented from dissipating outside the furnace from the discharge hole before landing on the slag bath in the hearth. Also, the slag bath located at the irradiation destination of the plasma torch always has a high surface temperature,
The incinerated ash always lands in the high temperature region of the slag bath, and is efficiently melted and turned into slag.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a melting furnace, 2 is a plasma torch,
3 is incineration ash, 4 is incineration ash supply hole, 7 is slag discharge hole, 1
Reference numeral 0 denotes a slag bath, 11 denotes a plasma torch driving device, 12 denotes a gas nozzle for supplying gas such as air, 13 denotes a gas nozzle driving device, 14 denotes a gas supply line for air or the like, 19 denotes an inducing fan, and 22 denotes an interlocking control device. .

The melting furnace body 1 is cylindrical and water-cooled on its outer wall.
The inside has a refractory structure, in which a plasma torch 2 is inserted into a corner from the upper surface to the side wall, and an incineration ash supply nozzle 4a and a gas nozzle 12 are inserted into an incineration ash supply hole 4 on the upper surface. The incineration ash 3 is supplied into the furnace main body 1 through an incineration ash hopper 5, a screw feeder 6, an incineration ash supply nozzle 4a, and an incineration ash supply hole 4 provided at an upper portion of the furnace main body 1. A slag discharge hole 7 is provided in the side wall of the main body 1, and the overflowed molten slag 8 is discharged out of the furnace, cooled, turned into a stone-like slag, and carried out by a conveyor 9.

The plasma torch 2 is provided with a driving device 11 for the plasma torch at the upper part of the furnace main body 1. The plasma torch 2 is movable in the axial direction as shown by an arrow a, and the center of the point P1 as shown by an arrow b. It is tiltable on a curve connecting a point P2 on the slag discharge hole 7 side and a point P3 on the incineration ash supply hole 4 side. This is to solve the problem that when the slag is continuously discharged, the slag is cooled and solidified at the slag discharge port 7 to close the gate, so that the slag does not flow out and the furnace body 1 has to be stopped. Then, the plasma torch is tilted about the fulcrum P1 so that the area where the plasma arc can be irradiated is from the slag bath 10 in the furnace main body 1 to the tip of the slag discharge port 7, and the slag in the slag discharge hole 7 is removed by the plasma arc. To prevent slag cooling,
So that it can be spilled continuously,
It is desirable that the plasma torch is arranged above the slag discharge hole 7.

Gas nozzle 1 provided in incineration ash supply hole 4
Reference numeral 2 denotes a cylinder surrounding the incineration ash supply nozzle 4a, a gas such as air from the gas supply line 14 is supplied to the gas supply hole 12a, and is located at the irradiation destination of the plasma torch from the incineration ash supply hole 4 side. The slag bath 10 is blown with gas to restrict the falling direction of the incinerated ash 3 introduced from the incinerated ash supply hole 4. A driving device 13 for changing the blowing angle from the gas nozzle 12 is provided in the upper part of the furnace main body 1. The driving device 13 tilts the gas nozzle 12 in the direction of arrow c around the fulcrum P4 to change the gas blowing angle. Let it. The gas nozzle driving device 13 is linked with the plasma torch driving device 11 and changes the blowing angle of the gas nozzle so that the gas is always blown toward the slag bath 10 located at the irradiation destination of the plasma torch.

When the blowing angle of the gas nozzle 12 changes, the incineration ash supply nozzle 4a also tilts.
5 is connected to a screw feeder 6. Note that the gas blowing strength is stronger than the flow of the trigger gas described later, and additionally, the furnace body 1 is blown by the gas blowing.
It should be noted that the temperature drop of the incineration ash 3 does not affect the melting of the incineration ash 3. Therefore, in order to prevent the temperature of the furnace main body 1 from dropping due to gas blowing, it is desirable to use a recycle gas described later.

The interlock control device 22 controls the plasma torch drive device 11 and the gas nozzle drive device 13 in an interlocking manner. The plasma torch 2 is connected to the slag discharge hole 7 (point P
When the plasma torch 2 is tilted toward the incineration ash supply hole 4 (point P3), the gas blowing direction from the gas nozzle 12 is moved to the right in the direction of the arrow c. The direction is moved to the left of the arrow c, and control is performed such that the gas blowing direction from the gas nozzle 12 always faces the slag bath 10 at the position where the plasma arc is irradiated from the plasma torch 2.

The inducing fan 19 creates a flow from the incineration ash supply hole 4 to the slag discharge hole 7 and performs a negative pressure operation in the furnace body 1 until the incineration ash 3 of fine particles is charged into the furnace or melted. During this period, the gas does not leak to the atmosphere outside the furnace main body 1. Therefore, the molten slag 8
At the same time, the trigger gas is discharged by the trigger fan 19, and the trigger gas rises in the duct 21 provided in the discharge hole 7. The trigger gas that has risen in the duct 21 is the bag filter 2
At 0, the fine particles contained in the trigger gas are collected and released to the atmosphere via the trigger fan 19 and the damper 18.

When supplied as a recycle gas to a gas supply line 14 described later, a gas circulation line 17 is provided.
Through the gas supply line 14. The damper 18 adjusts the amount of gas released to the atmosphere. When the inducing gas is used as a recycled gas, the amount of gas supplied to the gas circulation line 17 is adjusted.

The gas such as air supplied from the gas supply line 14 includes two types, a new gas supplied from the gas blower 16 and a recycled gas from the gas circulation line 17 described above. It is desirable to use them properly. An advantage of the recycle gas is that the temperature is relatively higher than that of fresh gas supplied from the gas blower 16 because the gas is discharged from the furnace body 1. Since the recycle gas having a relatively high temperature does not lower the temperature of the furnace body 1 due to the gas blowing and does not affect the melting of the incinerated ash, supplying the new gas from the gas blower 16 is performed by blowing. It should be performed only when the amount of gas for use becomes small.

The operation of such a plasma melting furnace is performed as follows. The incineration ash 3 is supplied into the furnace main body 1 via an incineration ash hopper 5, a screw feeder 6, an incineration ash supply nozzle 4a, and an incineration ash supply hole 4 provided at the upper part of the furnace main body 1. At this time, since the incineration ash 3 is supplied to the furnace body 1 together with the blowing gas from the gas nozzle 12, the incineration ash 3 is restrained by the flow of the blowing gas, and the incinerator ash is supplied from the incineration ash supply hole 4 to the slag discharge hole 7 by the inducing fan. Of the plasma torch 2 and fall onto the slag bath 10 located on the irradiation destination of the plasma torch 2 without being scattered outside the furnace.

Further, the driving device 13 for the gas nozzle works in conjunction with the driving device 11 for the plasma torch so that the gas is always blown toward the slag bath 10 located at the irradiation destination of the plasma torch 2. The gas nozzle 12 is moved in the direction of the arrow c in accordance with the tilt in the direction of the arrow b. Then, the incinerated ash 3 is always landed on the slag bath in the high-temperature region located at the irradiation destination of the plasma torch, and is efficiently melted into slag.

The molten slag 8 overflowing in the slag bath 10 is discharged out of the furnace through a slag discharge hole 7 in the side wall of the furnace body 1 and cooled to form a stone-like slag.
It is carried out by. At this time, the inducing gas induced by the inducing fan 19 rises in the duct 21 and the bag filter 2
The gas is supplied to the gas supply line through the gas circulation line 17 through the gas circulation line 17 through the zero and the inducing fan 19. Then, the gas enters the gas nozzle 12 through the gas supply hole 12a, and is blown again toward the slag bath 10 located at the irradiation destination of the plasma torch of the furnace main body 1.

Note that a swirler may be provided in the tip of the gas nozzle 12 to swirl the blowing gas. In this case, by swirling the blowing gas, the surrounding gas flow is entrained so that the incineration ash 3 can be prevented from dissipating, and at the same time, the particles of the incineration ash 3 can be given a moment, so that the particles adhere to the slag bath 10. Promotes the floor.

[0024]

According to the plasma melting furnace and the operation method of the present invention, a gas nozzle for blowing gas such as air toward a slag bath of a hearth is provided in an incineration ash supply hole of a melting furnace, and a plasma torch is tilted by a driving device. In this case, a driving device for changing the blowing angle of the gas nozzle in conjunction with the driving device for the plasma torch is provided in the melting furnace, and a gas such as air is always supplied from the incineration ash supply hole to the irradiation destination of the plasma torch. The incineration ash is constrained by the flow of gas such as air blown from the incineration ash supply hole to the slag bath located at the irradiation destination of the plasma torch so as to operate by blowing into the slag bath. Along with the flow in the furnace from the incineration ash supply hole to the slag discharge hole, it is prevented from being discharged from the discharge hole to the outside of the furnace before landing on the slag bath of the hearth. As a result, the incinerated ash surely reaches the slag bath on the hearth. In addition, since the incinerated ash always lands in the slag bath in the high-temperature area located at the irradiation destination of the plasma torch,
Melts efficiently and turns into slag.

If the gas discharged from the furnace body is used as the recycle gas as the gas for blowing, the recycled gas is discharged from the furnace body and thus has a relatively high temperature. It does not affect the melting of the incineration ash without lowering the temperature of the main body.

[Brief description of the drawings]

FIG. 1 is a structural view of a plasma melting furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 2 Plasma torch 3 Incineration ash 4 Incineration ash supply hole 5 Slag discharge hole 10 Slag bath 11 Plasma torch drive device 12 Gas nozzle 13 Gas nozzle drive device 22 Interlocking control device

Continuation of the front page (72) Inventor Tomio Suzuki 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Inside Kobe Research Institute, Kobe Steel Co., Ltd. (72) Inventor Narumi Tabashi 1 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel, Ltd.Kobe Research Institute, Inc. (72) Inventor Motoo Yamada 3-11-20 Wakao-ji Temple, Amagasaki City, Hyogo Kansai Electric Power Co., Inc. 54-21414 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23J 1/00 F23J 1/08 F23J 9/00 F23G 5/00 F23G 5/24-5/28 F23G 7/00 F27D 7/00-15/02

Claims (2)

(57) [Claims] 1. A melting furnace having an incineration ash supply hole and a slag discharge hole in which a slag bath is formed on a hearth, a plasma torch for generating a plasma arc in the slag bath,
A driving device that moves the plasma torch in the axial direction, and the irradiation direction can be tilted along a line connecting the incineration ash supply hole and the slag discharge hole. A gas nozzle that blows gas such as air toward a slag bath on the hearth, and a driving device that changes the blowing angle of the gas nozzle, wherein the driving device for the gas nozzle and the driving device for the plasma torch are linked. Characteristic plasma melting furnace. 2. A slag bath is formed on the hearth by generating a plasma arc with a plasma torch in the melting furnace body to melt incineration ash supplied from an incineration ash supply hole of the melting furnace body.
In a method for operating a plasma melting furnace in which molten slag overflowing from a slag bath is continuously discharged and cooled and solidified from a slag discharge hole, a gas such as air is blown into a melting furnace main body from a gas nozzle provided in the incineration ash supply hole, A method for operating a plasma melting furnace in which the incinerated ash is restrained by the flow of the blown gas and landed on a slag bath located at the irradiation destination of the plasma torch.