JP3500622B2 - Waste incineration residue melting furnace - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting furnace for melting an incineration residue generated in an incinerator, and in particular, a rod-shaped electrode is charged and arranged in a longitudinal direction in a furnace tank.
The present invention relates to an electric resistance type melting furnace for melting an incineration residue by Joule heat generated by an electric current flowing between electrodes via a molten slag in a furnace tank.

[0002]

2. Description of the Related Art Incineration residue is generated when waste is incinerated in an incinerator. This incineration residue consists of fly ash and incineration ash. Fly ash is carried as dust from the waste being incinerated as exhaust gas outside the furnace and collected by a dust collector, and contains a large amount of salts. The exhaust gas discharged from the incinerator contains HCl, and slaked lime may be blown into the exhaust gas for the purpose of removing HCl. In this case, the fly ash collected by the dust collector contains a large amount of calcium chloride that has reacted with HCl. On the other hand, incinerated ash is ash that remains on the grate after incineration and is recovered by the ash discharging device, or ash that has fallen from between the grate and is recovered.

Thus, the incineration residue generated by the incineration process is further melted in a melting furnace. An electric resistance type melting furnace is known as one of such waste melting furnaces. In this electric resistance melting furnace, a plurality of rod-shaped electrodes are partially charged into the material to be melted from the furnace ceiling to the inside of the material to be melted, electricity is supplied between the electrodes through the material to be melted, and the material to be melted is jouled. It generates heat. The material to be melted is heated by Joule heat and melted to form a molten slag.

However, as described above, when fly ash contains a large amount of salts, the difference in specific gravity causes
A molten salt layer is formed mainly by the molten salt generated from the fly ash. Since the electric conductivity of the molten salt is about 10 times higher than that of the molten slag, the electric current supplied to the electrode is short-circuited via the molten salt and becomes difficult to flow into the molten slag, so that it is sufficient for the molten slag. There is a risk that heat cannot be supplied and the incineration residue cannot be sufficiently melted.

As a first method for dealing with this problem, a method of raising the temperature of the molten salt layer to a high temperature of 1300 ° C. or higher and volatilizing sodium chloride or potassium chloride which are the main components of the molten salt can be considered.

As a second method, for example, a method of overflowing the molten salt out of the melting furnace and removing the molten salt has been proposed, as in JP-A-7-55119.

[0007]

However, in the first method described above, when the incineration residue is thrown into the furnace, it may spread to the upper part of the molten salt layer and hinder volatilization of the molten salt, so that the molten salt can be efficiently melted. May not be able to volatilize salt. Moreover, in the second method, in order to overflow the molten salt, the level of the molten salt layer or the slag layer must be controlled to be constant.

According to the present invention, it is not necessary to care about such a troublesome control of the level of the molten slag, the molten salt formed on the upper portion of the molten slag can be efficiently volatilized, and a short circuit between the electrodes due to the molten salt is prevented. It is an object to provide a waste incineration residue melting furnace capable of melting.

[0009]

According to the present invention, the above object is to provide a furnace tank with a supply port for charging waste incineration residues and an exhaust port for discharging generated gas in the furnace. In a melting furnace in which a plurality of rod-shaped electrodes are charged and arranged from above into the furnace tank and the incineration residue is melted by an electric current flowing between the electrodes through the molten slag in the furnace tank, Extend the space above the top surface to near the top surface of the molten slag.
The partition wall divides it into a supply space on the supply port side and an exhaust space on the exhaust port side.A maximum of one electrode is arranged on the supply space side with respect to the middle partition wall, and the other electrodes are arranged on the exhaust space side. It is achieved by placing in.

In the melting furnace of the present invention having such a structure,
The incineration residue charged from the supply port spreads on the upper surface of the molten slag, but stays in the supply space because it does not cross the intermediate partition wall. Therefore, in the exhaust space, the upper surface of the molten slag is not covered by the incineration residue and the molten salt
Is discharged through the gap between the partition wall and the top surface of the molten slag.
Move to the air space side. This molten salt is volatilized becomes hot by the heat from the molten slag in the exhaust space. That is, sodium salt and potassium salt are evaporated from the molten salt and discharged from the exhaust port. Therefore, the molten salt does not exist on the molten slag on the exhaust space side, and a short circuit between the electrodes via the molten salt is avoided. Molten salt exists on the molten slag in the supply space, but even if there is only one electrode in the supply space, the other electrodes are arranged in the exhaust space in which no molten salt exists. There is no short circuit between the molten salts. In this way, all the current between the electrodes flows through the molten slag, so that heat can be effectively supplied to the molten slag.

[0011]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) In FIG. 1, reference numeral 1 is a furnace body which is a furnace tank, and a plurality of rod-shaped electrodes 2 are vertically movable on a furnace lid 1A of the furnace body 1. Is pierced through. In the furnace body 1, a furnace lid 1A is provided with a supply port 3 for incineration residue and an exhaust port 4 for exhaust gas, and further, a slag discharge port 5 is provided at a lower portion on a side portion. The plurality of electrodes 2 are connected to an AC power source (not shown) outside the furnace body 1. When the AC power source has a single phase, two electrodes 2 are provided as a pair, and when the AC power source has a three phase, three electrodes are provided as a set. Figure 1
Then, it has three electrodes 2 (2A, 2B, 2C) and is connected to a three-phase power supply.

The furnace main body 1 is usually formed in a cylindrical shape, the outer circumference of which is made of steel, and a refractory is attached and protected inside thereof. From the furnace lid 1A of the furnace body 1, at a position closer to the left side than the lateral center position in FIG.
Are hung down. In the furnace main body 1, Joule heat is generated by energization between the plurality of electrodes 2 via the melt, and the melt has a molten slag layer 7 in the lower layer and a molten salt layer 8 in the upper layer due to the relationship of specific gravity. Formed separately,
The partition wall 6 extends near the upper surface of the molten slag layer 7, and a space above the upper surface of the molten slag layer 7 is provided with a supply space 9 on the side where the supply port 3 exists and an exhaust port 4. It is partitioned into the exhaust space 10 on the existing side. Further, an appropriate number of ventilation windows 6A are formed on the upper portion of the partition wall 6 as shown in FIG. 2 which is a view taken along the line AA of FIG. The ventilation window 6A is not essential in the present invention.

Next, the case where the incineration residue containing salt is melted in the electric resistance type melting furnace will be described.

The incineration residue is charged and supplied from the supply port 3 of the furnace body 1 into the furnace tank. The incineration residue that was put into the space 9
Inside the molten salt layer 8 is diffused to form a deposited layer 11. Since the incineration residue forming the deposit layer 11 has the intermediate partition wall 6, it slightly flows out from the gap at the lower edge portion of the intermediate partition wall 6 and does not enter the exhaust space 10. The incineration residue that is charged and supplied from the supply port 3 to form the deposited layer 11 is on the melt (the molten slag layer 7 and the molten salt layer 8) and is heated from both layers to be gradually melted, resulting in a difference in specific gravity. Is divided into a molten slag layer 7 and a molten salt layer 8. The specific gravity of the molten slag is about 2.7, and the specific gravity of the molten salt is about 2.1. Then, the molten slag is appropriately taken out from the slag discharge port.

On the other hand, in the exhaust space 10, the incineration residue does not exist on the upper surface of the molten slag layer 7 as described above. Therefore, the ambient temperature in the exhaust space 10 is a high temperature close to the temperature of the molten slag by directly receiving heat from the molten slag layer 7, and the molten salt flowing in from the supply space 10 has sodium as its main component. Salts and potassium salts evaporate and volatilize, and are sucked and discharged from the exhaust port 4. Therefore, the molten salt layer is not formed on the molten slag layer 7 in the exhaust space 10. When the sodium salt or potassium salt is discharged, the gas such as H ₂ O, CO, or H ₂ generated in the supply space 9 due to the suction force at the exhaust port 4 passes through the ventilation window 6A and the exhaust space. It is exhausted through 10 together with the sodium salt and potassium salt. When the ventilation window 6A is not formed in the partition wall 6, an exhaust port is appropriately provided on the side of the supply space 9 for exhausting air.

The operation of the apparatus according to the present embodiment will be described in more detail. The molten slag layer 7 and the molten salt layer 8 are covered by the incineration residue charged in the supply space 9, and the ambient temperature is the exhaust space. Since it is lower than 10, the molten salt is hard to be volatilized.

On the other hand, in the exhaust space 10, since the molten slag layer 7 is not covered at all, the ambient temperature is close to the slag temperature, and the sodium salt and potassium salt which are the main components of the molten salt are easily volatilized. As a result, one electrode 2A is on the supply space 9 side and is in contact with the molten salt layer 8, while the other electrodes 2B and 2C are on the exhaust space 10 side and are not in contact with the molten salt. The electric current supplied between 2A, 2B, and 2C is not short-circuited by the molten salt, and stable operation is possible.

The ambient temperature of the supply space 9 is 600 ° C.
It is possible to sufficiently suppress the generation of HCl by keeping the temperature below and evaporating the water that causes the generation of HCl above the incineration residue on the molten salt layer 8. It is desirable to maintain the atmosphere temperature of the exhaust space 10 at 1300 ° C. or higher because the sodium salt or potassium salt, which is the main component of the molten salt, can be efficiently vaporized.

A large amount of calcium chloride CaCl in the incineration residue
_When it contains ₂ , it is considered that CaCl ₂ forms a layer on the slag as a molten salt. Since volatilization of calcium chloride requires 1600 ° C. or higher, a large amount of energy is required. In this case, it is desirable to put at least one of a sodium compound and a potassium compound into the furnace, dissolve calcium chloride in the slag as calcium oxide CaO, and volatilize the chlorine content as sodium chloride NaCl or potassium chloride KCl. In this case, it is possible to add, as the sodium compound or potassium compound, a sodium content or a potassium content that is equal to or more than the molar amount obtained by subtracting the molar amounts of sodium and potassium in the incineration residue from the chlorine content contained in the incineration residue. desirable.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention. In the figure, the same parts as those of FIG. 1 showing the first embodiment are designated by the same reference numerals and the description thereof is omitted.

In FIG. 3, the electrodes 2 (2A, 2B, 2
All of C) are located on the right side of the partition wall 6, that is, on the exhaust space 10 side. Therefore, the partition wall 6 is provided at a position that is located considerably to the left.

The partition wall of the first embodiment is immovable,
It is suitable when there is little fluctuation in the level of molten slag,
The present embodiment is suitable when the level fluctuation is relatively large. That is, the partition wall 6 of the present embodiment is as shown in FIG.
As you can see, it can be raised and lowered. The partition wall 6 is suspended by a wire 12, the wire 12 is guided by a pulley 13 and the like, and a winding machine 15 driven by a motor 14 winds or sends out the wire. Thus, the position of the partition wall 6 in the height direction can be set freely. The height of the partition wall 6 is set by observing the level of the molten slag layer 7 and operating the motor so that the lower edge of the partition wall 6 is close to the upper surface of the molten slag layer 7.
This setting can be done manually or controlled automatically.

It should be noted that the present invention is not limited to the illustrated example and can be modified. For example, the lateral position of the intermediate partition wall in FIG. 1 or 3 can be changed according to the amount of incineration residue or the like to be charged. This can be set, for example, by making the inner partition wall rotatable at a supported position on the furnace lid and changing the position of the lower edge of the inner partition wall in the lateral direction.

[0026]

As described above, according to the present invention, the upper space of the furnace body is divided into the supply space and the exhaust space by the partition wall extending near the upper surface of the molten slag , and the partition wall and the molten slurry are separated.
Since it was decided to form a gap between the upper surface of the grayed, incineration
Exhaust only the molten salt while preventing the residue from entering the exhaust space
It becomes possible to flow into the space side, the molten salt can be efficiently vaporized in the exhaust space, without causing a short circuit between the electrode and the molten salt layer,
This brings about an effect that stable operation can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a melting furnace according to a first embodiment of the present invention.

FIG. 2 is a view on arrow AA in FIG.

FIG. 3 is a schematic view showing a melting furnace according to a second embodiment of the present invention.

[Explanation of symbols]

1 furnace tank (main furnace) 2 electrodes 3 supply ports 4 exhaust port 6 partition walls 7 Molten slag layer 9 supply space 10 exhaust space

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-262162 (JP, A) JP-A-53-70005 (JP, A) JP-A-9-112850 (JP, A) JP-A-8- 61858 (JP, A) JP-A-7-77319 (JP, A) JP-A-48-41977 (JP, A) JP-A-7-42924 (JP, A) JP-A-7-55119 (JP, A) 5-27596 (JP, U) International Publication 96/010097 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F23G 5/00 F23J 1/00 F27B 3/08 F27D 3/15

Claims (3)

(57) [Claims] 1. A furnace tank is provided with a supply port for charging a waste incineration residue and an exhaust port for discharging a gas generated in the furnace, and a plurality of rod-shaped electrodes are installed in the furnace tank from above. In a melting furnace in which the incineration residue is melted by an electric current flowing between electrodes through the molten slag in the furnace tank, the space above the upper surface of the molten slag in the furnace tank, the upper surface of the molten slag
A partition wall extending close to the partition wall divides it into a supply space on the supply port side and an exhaust space on the exhaust port side.A maximum of one electrode is arranged on the supply space side with respect to the middle partition wall, and the other electrodes are exhausted. A waste incineration residue melting furnace characterized by being placed on the space side. 2. The intermediate partition wall is always close to the level of the upper surface of the molten slag layer in the furnace tank as the level changes.
The waste incineration residue melting furnace according to claim 1, wherein the furnace is vertically movable. 3. The waste incineration residue melting furnace according to claim 1, wherein the furnace atmosphere temperature in the supply space is 600 ° C. or lower, and the furnace atmosphere temperature in the exhaust space is 1300 ° C. or higher.