JPH1089658A - Melting treatment method of burned salt-containing residue and melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress drastically the evaporative dissipation of low boiling point substances such as alkali metallic salts, e.g. NaCl, KCl, and the like. SOLUTION: The melting furnace is provided with an electrode 13 that is inserted into the inside of a furnace and a burned residue feeding cylinder 15 that is inserted in the upper part of the furnace, a furnace main body 10 is partitioned into a slug retaining part 11 that retains the molten slug and heats it, and a salt retaining part 12 that is arranged to the part being extended to the upper part of the slug retaining part 11 and retains the molten salt, the burned residue feeding cylinder 15 is inserted so that the lower edge of it is positioned lower than the melt surface of the molten salt layer 51 and a cooling device 16 provided at the external circumferential part of the salt retaining part 12 for cooling the molten salt layer 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting incineration residues containing salts such as municipal waste incineration residues and a melting furnace for melting the incineration residues.

[0002]

2. Description of the Related Art Most of the incineration residues generated when municipal solid waste and industrial waste are incinerated are disposed of in landfills. However, as it becomes difficult to secure landfill sites, it is required to reduce the volume. Was. Also, of the incineration residues, the ash (fly ash) scattered with the combustion exhaust gas and collected by the dust collector contains heavy metals such as lead and cadmium, and is designated as a specially controlled general waste. At the time of its disposal, it must be treated to detoxify heavy metals.
Therefore, there is a need to reduce the volume of the residue directly taken out of the incinerator and to render fly ash harmless.

[0003] As a technique capable of simultaneously reducing the volume of incineration residues and insolubilizing and detoxifying heavy metals in response to such problems, a treatment method for melting and solidifying incineration residues has been developed. As one method of the melt-solidification treatment, there is a method of sequentially melting the charged incineration residues while keeping the incineration residue melt in the furnace. In the method of melting the incineration residue in this way, while the generated melt stays in the furnace, the components in the melt are separated by a difference in specific gravity, and separated into a molten slag layer and a molten salt layer. In addition, the molten material can be separated and discharged into a molten slag and a molten salt.

However, in the above melt processing method,
The generated molten salt always remains in the furnace, and since the molten salt contains a large amount of chlorides of alkali metals such as NaCl and KCl having a low boiling point, these low-boiling substances volatilize in large amounts. Then a problem arises. When low-boiling substances evaporate, the evaporated alkali metal salts condense and adhere in the exhaust system equipment, and these deposits can cause clogging of the exhaust system or corrode the equipment. Therefore, stable operation of the melting furnace is hindered.

As a technique for solving such a problem, Japanese Patent Application Laid-Open No. 7-42924 discloses a melting furnace in which the evaporation of low-boiling substances is suppressed and a melting treatment method using the melting furnace. ing. This technology relates to a melting furnace of an electric resistance heating type, and in the melting process by this technology, electricity is supplied between electrodes immersed in a molten material of incineration residue staying in the furnace, so that The melt is heated by its own electric resistance heat, and the charged incineration residues are sequentially melted.

FIG. 10 is a longitudinal sectional view showing the electric resistance heating type melting furnace. Reference numeral 30 denotes a furnace body, 31 denotes an electrode, 50 denotes an incinerated residue, 52 denotes a molten slag layer formed by melting the incineration residue, and 51 denotes a molten salt layer generated by melting salts in the incineration residue. Reference numeral 32 denotes an incineration residue input port, 33 denotes an exhaust gas discharge port, and 34 denotes a melt discharge port. In this melting furnace, the molten salt layer 51 inside the partition wall 35 provided between the ceiling wall of the furnace main body 30 and the melting region is covered with the incineration residue 50 injected, and the outside of the partition wall 35 is covered. The molten salt layer 51 is covered with a powder material 38 such as carbon having a melting point higher than the furnace temperature and a specific gravity smaller than that of the molten salt.
The volatilization of low-boiling substances from water is suppressed.

[0007]

The incineration residue containing salts is a mixture of oxides having a melting point of 1400 ° C. to 1600 ° C. and salts having a melting point of 700 ° C. to 800 ° C. Since the melting process is a process that melts all the components in the incineration residue, in the operation of the melting furnace, heating is performed until the temperature reaches the high-temperature region where all the components melt, that is, the temperature equal to or higher than the melting point of the oxide. You. For this reason, the salts having a low melting point are heated as they are and become high-temperature molten salts. The salts have a boiling point of about 1400 ° C. to 1600 ° C. and a vapor pressure of 11
Since the temperature rises sharply from above about 00 ° C., low-boiling substances are very easily volatilized in the furnace.

In this regard, in the above-mentioned prior art, the molten salt is covered with a powdered material such as incineration residue or carbon, but the vapor pressure of the molten salt, which is a volatile source of low-boiling substances, can be suppressed. Rather, it is a treatment that only aims at the trapping effect of incineration residues, carbon, and the like, so that the effect of suppressing volatilization of low-boiling substances cannot be expected much.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for melting incineration residues containing salts, which can greatly suppress the evaporation of low-boiling substances, and a melting furnace therefor. I do.

[0010]

According to a first aspect of the present invention, there is provided a melt processing method for melting an incineration residue containing salts and retaining the melt in a melting furnace. In a method for treating incineration residues by separating a molten slag layer and a molten salt layer and separating and discharging the molten slag and the molten salt, the temperature of the molten salt layer is adjusted to a predetermined range.

According to a second aspect of the present invention, there is provided a melt processing method according to the first aspect, wherein incineration residues containing salts are charged into the molten salt layer.

In the melting furnace according to the third aspect of the present invention, the incineration residue containing salts is melted, and the melt is retained in the melting furnace to be separated into a molten slag layer and a molten salt layer. In a melting furnace that separates and discharges slag, an electrode rod inserted into the furnace, and an incineration residue charging pipe provided at the furnace upper part, and a furnace main body, a slag retaining section that retains and heats the molten slag And a portion extending above the slag retaining portion, which is divided into a salt retaining portion for retaining the molten salt, and a means for cooling the molten salt layer is provided on an outer peripheral portion of the salt retaining portion. It is characterized by:

According to a fourth aspect of the present invention, there is provided a melting furnace for melting an incineration residue containing salts, retaining the melt in the melting furnace to separate it into a molten slag layer and a molten salt layer. In a melting furnace that separates and discharges slag, an electrode rod inserted into the furnace, and an incineration residue charging pipe provided at the furnace upper part, and a furnace main body, a slag retaining section that retains and heats the molten slag And a cross-sectional area inside the furnace body, which is reduced, and is protruded and extended above the slag retaining portion, and is divided into a salt retaining portion for retaining the molten salt.

According to a fifth aspect of the present invention, there is provided a melting furnace.
In the melting furnace according to the invention, a means for cooling the molten salt layer is provided on an outer peripheral portion of the salt retaining portion.

According to a sixth aspect of the present invention, there is provided a melting furnace.
In the melting furnace according to the invention, a means for heating an upper portion of the molten salt layer is provided.

According to a seventh aspect of the present invention, there is provided a melting furnace.
Alternatively, in the melting furnace according to the fifth aspect of the present invention, a means for cooling the molten salt layer is provided on an outer peripheral portion of a lower part of the salt accumulation section, and a means for heating the upper part of the molten salt layer is provided. And

[0017] The melting furnace according to the invention of claim 8 is characterized by claim 6.
Alternatively, in the melting furnace according to the invention of claim 7, a means for heating an upper portion of the molten salt layer is provided on an outer peripheral portion of the salt retaining section.

According to a ninth aspect of the present invention, there is provided a melting furnace.
Alternatively, in the melting furnace according to the invention of claim 7, a means for heating an upper portion of the molten salt layer is inserted in the furnace.

A melting furnace according to a tenth aspect of the present invention is the melting furnace according to the ninth aspect, wherein the heating means inserted into the furnace is immersed in the molten salt layer.

The melting furnace according to an eleventh aspect of the present invention is characterized in that, in the melting furnace according to the ninth aspect of the present invention, the heating means inserted into the furnace is arranged above the molten salt layer.

According to a twelfth aspect of the present invention, there is provided a melting furnace according to any one of the third to eleventh aspects,
It is characterized in that the lower end of the incineration residue charging pipe is inserted so as to be positioned below the level of the molten metal when the molten salt layer is formed.

According to a thirteenth aspect of the present invention, in the melting furnace according to the twelfth aspect, the lower end of the incineration residue charging pipe is lower than the molten metal level when the molten salt layer is formed by 20c.
It is characterized by being inserted to a position deeper than m.

In the present invention, the incineration residue containing salts is dust ash (fly ash) generated when municipal solid waste is incinerated. It refers to both of those where dust ash is mixed.

In each of the above-mentioned inventions, it is a basic requirement that the temperature rise of the molten salt layer be suppressed so that the vapor pressure of the low-boiling substance does not increase, thereby suppressing the volatilization of the low-boiling substance. I am trying to do that.

For this reason, in the melting treatment method according to the present invention, the temperature of the molten salt layer is adjusted so as to fall within a predetermined range. The low-boiling substances contained in the incineration residue are mainly chlorides of alkali metals such as NaCl and KCl.
Since the temperature is around 0 ° C., in order to suppress the volatilization, the temperature of the molten salt layer must be controlled so as to be 1000 ° C. or less. However, if the temperature of the molten salt layer is lower than about 700 ° C., the melt may be solidified. Therefore, when controlling the temperature of the molten salt layer, it is appropriate to set the range of 700 ° C. to 1000 ° C. as the predetermined control temperature.

The molten salt layer generated when the incineration residue is melted is heated by the heat transfer from the high-temperature molten slag layer that is in contact therewith. Then, in order to prevent the temperature of the molten salt layer from increasing, the amount of heat transfer from the molten slag layer is reduced, or the amount of heat radiation from the molten salt layer is increased, or the molten salt layer is It is necessary to take measures such as artificial cooling. For this reason, it is desirable that the melting furnace used for melting the incineration residue containing salts has a structure in which consideration is given to maintain the temperature of the molten salt layer in an appropriate range.

First, in the present invention, as one of means for lowering the temperature of the molten slag layer, means for cooling the molten salt layer at the outer peripheral portion of the salt retaining section is provided, and the molten salt layer is forcibly cooled.

There are several measures to reduce the amount of heat transfer from the molten slag layer to the molten salt layer. However, the above-mentioned reduction in the amount of heat transfer requires charging the incineration residue into the molten salt layer. Is also achieved by For this reason, in the melting furnace of the present invention, the incineration residue charging pipe is disposed such that the lower end thereof is lower than the molten metal level when the molten salt layer is formed,
The lower part of the incineration residue charging pipe is immersed in the molten salt layer. When the incineration residue is charged in such a state, the incineration residue is gradually settled and dispersed in the molten salt layer, and a portion where the incineration residue and the molten salt are mixed at the lower portion of the molten salt layer (hereinafter, a mixed layer). You can say). This mixed layer is in a state where the particles of the incineration residue are suspended or in a slurry state, and a solid component having poor thermal conductivity is mixed. Lower than. For this reason, the mixed layer becomes a region that hinders heat transfer, and an excessive rise in temperature of the molten salt layer is suppressed.

Another method for reducing the amount of heat transfer from the molten slag layer is to reduce the area of the interface between the molten salt layer and the molten slag layer.
In this regard, in the melting furnace according to the present invention, the upper part of the furnace body has a reduced shape, the molten salt is retained in the reduced portion, and the molten slag is stored in the unreduced portion thereunder. Is to stay. Therefore, the area of the interface between the two layers is reduced, the amount of heat transferred from the molten slag layer to the molten salt layer is reduced, and an excessive rise in the temperature of the molten salt layer is suppressed.

When the molten salt is retained in the reduced portion, the ratio of the furnace wall area to the retained amount of the molten salt becomes large, the amount of heat radiation from the molten salt layer increases, and excessive molten salt layer Temperature rise is suppressed.

Further, when the molten salt is retained at the reduced portion, the ratio of the area of the outer periphery of the furnace wall to the retained amount of the molten salt becomes large, and only a small amount of the molten salt is retained.
Since the height of the molten salt layer can be increased, it is easy to provide cooling means outside the furnace wall to forcibly cool the molten salt layer.

As described above, in the present invention, as one of means for suppressing a rise in the temperature of the molten salt layer, the lower end of the incineration residue charging pipe is positioned below the molten metal level of the molten salt layer. Then, the incineration residue is charged into the molten salt layer to form a mixed layer that prevents heat transfer below the molten salt layer. However, in this case, since the place where the mixed layer is to be formed must be below the molten salt layer, the incineration residue charging pipe must be immersed to a depth where the mixed layer can be formed below the molten salt layer. During operation, the molten salt layer must be maintained at a certain height.

However, since the surface of the molten salt layer is easily cooled, if the operation is performed with the height of the molten salt layer increased, an excessive temperature drop occurs on the surface and the fluidity of the molten salt decreases. Its emission may be difficult. Therefore, in the present invention, a means for heating the upper part of the molten salt layer is provided,
Take measures to prevent excessive temperature drop.

[0034]

FIG. 1 is a plan view showing an embodiment of a melting furnace according to the present invention, and FIG.
It is sectional drawing of a part. This melting furnace is an electric resistance heating type furnace, and its main part is constituted by a melting furnace main body 10, a plurality of electrodes 13, and a plurality of incineration residue charging tubes 15. In the figure, 50 is the incineration residue containing the introduced salts, 51
Denotes a molten salt layer, and 52 denotes a molten slag layer.

The melting furnace main body 10 is divided into a part for retaining molten slag and a part for retaining molten salt. The lower part of the melting furnace main body 10 is a slag retaining part 11, and the upper part thereof is a salt retaining part 12. Has become. The melting furnace body 1
A plurality of electrode insertion portions 14 having insertion holes for the electrodes 13 are provided inside 0.

The slag retaining section 11 retains the molten slag therein, energizes and heats the electrodes 13 immersed in the molten slag layer 52, and maintains the molten slag layer 52 at a high temperature. And serves to melt the incineration residue sent from the furnace via the incineration residue charging pipe 15.

The incineration residue charging section 12 is provided with three incineration residue charging pipes 15.
Numeral 5 penetrates the furnace lid of the salt retaining section 12 and is inserted so that its lower end is located below the level of the molten metal when the molten salt layer 51 is formed.

When charging the incineration residue, a mixed layer must be formed below the molten salt layer 51, and the upper portion must be in a state where the powder of the incineration residue does not exist. It is necessary to insert the incineration residue charging pipe 15 to a certain level.

According to the test results performed by the present inventor, the lower end of the incineration residue charging pipe 15 is set at a position 2 degrees lower than the molten metal level of the molten salt layer.
It is desirable to insert to a depth of about 0 cm or more. FIG. 9 shows that the insertion depth of the incineration residue charging pipe 15 was changed variously during the operation of the test furnace for discharging the molten salt by the overflow method with the throughput of the incineration residue being 100 kg / h. It is a figure which shows the result of having investigated the content of the insoluble matter (water-insoluble matter in the unmelted incineration residue) after sampling the salt sample, adding water to the sample, and stirring. According to this figure, if the lower end of the incineration residue charging pipe 15 is not inserted to a position deeper than the overflow level of the molten salt (the level of the molten salt layer), unmelted incineration residue is contained in the overflowing molten salt. Is mixed in a large amount. And
When the lower end of the incineration residue charging pipe 15 is inserted to about 20 cm, the amount of unmelted incineration residue mixed in becomes extremely small.

Since the incineration residue charging pipe 15 only needs to have a function of lowering the incineration residue that has been charged and putting it into the molten salt layer 51, the shape thereof is cylindrical. The shape is not limited and may be square or other shapes.

Further, a cooling device 16 is provided on the outer periphery of the salt retaining section 12. The cooling device 16 is provided for forcibly cooling the molten salt layer 51,
The water cooling tube has a structure embedded in the refractory, and is provided from near the level of the interface between the molten salt layer 51 and the molten slag layer 52 from the level of the molten salt layer 51.

The operation for melting the incineration residue containing salts by the melting furnace having the above configuration is performed as follows.

After the incineration residue is weighed, the molten salt layer 51
It is thrown into the incineration residue charging pipe 15 immersed inside,
The lower part is filled. This incineration residue gradually descends in the incineration residue charging pipe 15 by its own load while being preheated, and is charged into the molten salt layer 51 formed in the salt accumulation section 12. The incineration residue 50 charged into the molten salt layer 51 is dispersed while gradually settling to form a portion where the incineration residue is suspended, that is, a mixed layer 51a. As described above, the mixed layer 51a has a function of preventing heat transfer from the molten slag layer 52 to the molten salt layer 51 and suppressing an excessive rise in temperature of the molten salt layer 51.

The incineration residue 50 charged in the molten salt layer 51
Is partially melted in the molten salt layer 51, but the rest drops to the interface with the molten slag layer 51 maintained at a high temperature and melts there. When the incineration residue is melted, its components are separated by a difference in specific gravity, and a molten salt layer 51,
Three layers of the molten slag layer 52 and the molten metal layer 53 are formed.

The molten slag layer 52 in the slag retaining section 11
Is heated by the electric resistance heat of the molten slag itself during energization between the electrodes 13. The temperature of the molten slag layer 52 is maintained in the range of 1400 ° C to 1600 ° C by adjusting the input power.

On the other hand, the temperature of the molten salt layer 51 formed in the salt accumulating portion 12 is based on the measured value of the thermometer 22 for measuring the intermediate portion, the detecting portion of which is arranged at the intermediate portion of the molten salt layer 51. Adjustment of the cooling device 16 is maintained in an appropriate range. That is, the cooling device 1 is set so that the temperature of the intermediate portion of the molten salt layer 51 measured by the thermometer 22 falls within a range (700 ° C. to 1000 ° C.) in which low-boiling substances do not volatilize.
The amount of cooling water flowing to 6 is adjusted.

Each of the above-mentioned melts is separately extracted. First, the molten salt is extracted from a salt discharge port 17 provided on a side wall above the salt stagnation section 12 (a position above the lower end of the incineration residue charging pipe 15). Since almost no solid content is contained, fluidity is maintained. Therefore, the salt outlet 1
7, the molten salt can be extracted at a small flow rate, and an overflow method can be adopted for the extraction.

The molten salt is discharged in the desired state as described above because the incineration residue charging pipe 15 is immersed in the molten salt layer 51 and the salt discharge port 17 is connected to the incineration residue charging pipe 15. Is provided above the lower end of the molten salt, and is located above the level at which the mixed layer 51a in which the incineration residue is suspended is formed. This is because the phenomenon that the residue is mixed does not occur.

If the incineration residue charging pipe 15 is made of the molten salt layer 5
1 and the incineration residue is charged on the molten salt layer 51, the incineration residue is suspended in the entire molten salt layer,
The molten salt is extracted with the incineration residue mixed therein. In such a state, the viscosity of the molten salt is significantly increased, the fluidity of the molten salt is reduced, and a problem that the discharge of the molten salt itself becomes difficult is caused.

The molten slag is continuously or intermittently extracted from a slag discharge port 18 provided on a side wall above the slag retaining section 11. The furnace body 10 is divided into a slag retaining section 11 and a salt retaining section 12. Configuration
At the time of the extraction, the level of the interface between the molten salt layer 51 and the molten slag layer 52 must be located below the salt accumulating portion 12, that is, near the lower portion of the cooling device 16, and the level must not be changed. No.

Therefore, the molten salt layer 51 and the molten slag layer 5
It is necessary to extract the molten slag while grasping the level of the interface of No. 2. By the way, the temperature in the height direction of the molten salt layer 51 rises as it approaches the interface with the molten slag layer 52. Therefore, if the temperature near the level of the interface is continuously measured, the position of the interface can be determined. You can figure out. Therefore, if the detection unit adjusts the amount of molten slag withdrawn so that the measured value of the lower measurement thermometer 23 disposed below the molten salt layer 51 is maintained at a predetermined value, the molten salt layer 51 and The interface of the molten slag layer 52 is maintained at a predetermined level.

Then, the molten metal is intermittently extracted from a metal outlet 19 provided on the side wall below the slag retaining portion 11. In addition, gas generated during melting is extracted from the exhaust gas outlet 20 and is separately processed.

FIG. 3 is a plan view showing another embodiment of the melting furnace according to the present invention, and FIG. 4 is a cross-sectional view taken along a line BB in FIG. 3 and FIG. 4, FIG. 1 and FIG.
The same reference numerals are given to the portions having the same configuration as the melting furnace according to the above, and the description is omitted. In this example, the salt retaining portion 12 is provided at the center of the slag retaining portion 11 with its inner diameter (cross sectional area inside the furnace body) greatly reduced with respect to the inner diameter of the slag retaining portion 11. When the salt retaining portion 12 and the slag retaining portion 11 are viewed from the side, their shapes are convex. And the electrode insertion part 14 is arrange | positioned around the salt retention part. For this reason, the salt retaining portion 12 and the electrode insertion portion 14 constituting the melting furnace main body 10 protrude and extend above the slag retaining portion 11. In addition, an incineration residue charging pipe 15 is provided at the center of the salt accumulation section 12.

In the operation using the melting furnace, the interface between the molten salt layer 51 and the molten slag layer 52 is maintained in the salt retaining section 12 having a reduced inner diameter.

As described above, by reducing the salt stagnant portion 12, the amount of heat transferred from the molten slag layer 52 to the molten salt layer 51 is reduced, and the amount of heat radiated from the furnace wall is increased. Thus, a rise in the temperature of the molten salt layer is further suppressed. For this reason, the required amount of cooling heat of the molten salt layer is extremely reduced, and the load on the cooling device 16 is greatly reduced. In a small melting furnace in which the required amount of cooling heat is further reduced, it may not be necessary to equip the cooling device 16.

FIG. 5 is a longitudinal sectional view showing still another embodiment of the melting furnace according to the present invention. In FIG. 5, FIG.
The same components as those of the melting furnace shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. In this example, an induction heating coil 24a as a heating means is provided on the outer peripheral portion of the salt retaining section 12. The induction heating coil 24a is for heating the upper portion of the molten salt layer 51, and is arranged near a level where a salt discharge port (not shown) is provided.

In the operation of the melting furnace having the above configuration,
The temperature of the molten salt layer 51 formed in the salt retaining section 12 is adjusted as follows. Based on the measurement value of the thermometer 22 for measuring the intermediate portion where the detecting portion is disposed in the intermediate portion of the molten salt layer 51, the temperature of the intermediate portion of the molten salt layer 51 is set in a range (700 (1000 ° C. to 1000 ° C.), the amount of cooling water flowing to the cooling device 16 is adjusted. When the operation is continued while performing such temperature adjustment, the detection unit measures the value measured by the upper measurement thermometer 21 disposed above the molten salt layer 51 (the temperature above the molten salt layer 51). Is reduced to around 700 ° C. and tends to further decrease, the induction heating coil 24a is energized, and the upper portion of the molten salt layer 51 is heated.

FIG. 6 is a longitudinal sectional view showing still another embodiment of the melting furnace according to the present invention. In FIG.
The same components as those of the melting furnace shown in FIGS. 3 and 4 are denoted by the same reference numerals, and description thereof is omitted. In this example, an induction heating coil 24a as a heating means is provided on the outer peripheral portion of the salt retaining section 12. This induction heating coil 2
4a is for heating the upper part of the molten salt layer 51, and is arranged near the level where a salt discharge port (not shown) is provided.

In the operation of the melting furnace having the above configuration,
The temperature control of the molten salt layer 51 formed in the salt retaining section 12 is performed in the same manner as in the case of the melting furnace of FIG. Based on the measurement value of the thermometer 22 for measuring the intermediate portion, the cooling device 16
The amount of cooling water flowing through the molten salt layer 51 is adjusted, and the temperature of the intermediate portion of the molten salt layer 51 is controlled in the range of 700 ° C to 1000 ° C. Next, when the measured value of the thermometer 21 for measuring the upper part decreases to around 700 ° C. and tends to further decrease, the induction heating coil 24 a is energized to heat the upper part of the molten salt layer 51, and Is maintained above.

In the above description of FIGS. 5 and 6,
Although only the case where the means for heating the upper portion of the molten salt layer 51 is provided on the outer peripheral portion of the salt accumulation section 12 is described, the purpose of heating the upper portion of the molten salt layer 51 is to prevent the discharge of the molten salt from being hindered. The purpose of the present invention is to prevent a decrease in the fluidity of the molten salt in the vicinity of the molten salt discharge port. For this reason, means for heating only the vicinity of the molten salt discharge port may be provided.

FIG. 7 is a longitudinal sectional view showing an example of means for heating the molten salt near the molten salt discharge port. In FIG. 7, 1
2 is a salt retention section of the melting furnace main body, 17 is a molten salt discharge port, 5
Reference numeral 1 denotes a molten salt layer. Reference numeral 24b is an electrothermal heater with a protective tube as a heating means. This electric heater 24b is shown in FIG.
6, which is inserted into the furnace through the furnace lid and immersed in the molten salt layer 51. Then, the molten salt layer is directly heated. The electric heater 24b is
If necessary, they are arranged at a plurality of places near the molten salt discharge port.

In the operation of the melting furnace provided with the above-mentioned heating means, the temperature of the upper portion of the molten salt layer 51 is adjusted as follows. When the measurement value of the upper measuring thermometer (not shown) arranged above the molten salt layer 51 of the detecting unit decreases to around 700 ° C. and tends to further decrease, the electric heater 24 b And heating is started.

FIG. 8 is a longitudinal sectional view showing another example of the means for heating the molten salt near the molten salt discharge port. In FIG.
12 is a salt retention section of the melting furnace main body, 17 is a molten salt discharge port,
Reference numeral 51 denotes a molten salt layer. Reference numeral 24c denotes an electric heater with a protective tube. The electric heater 24c is provided in the melting furnace shown in FIGS. 1 to 6, and is inserted into a space in the furnace through the side wall of the salt retaining section 12. Then, the molten salt layer is heated by radiant heat. The electric heater 24c is arranged at a plurality of locations near the molten salt discharge port as needed.

In the operation of the melting furnace provided with the heating means, the temperature of the upper portion of the molten salt layer 51 is adjusted in the same manner as in FIG. When the measured value of the thermometer (not shown) of the heater decreases to around 700 ° C. and tends to further decrease, the electric heater 24
c is energized and heating is started.

The heating means shown in FIGS. 7 and 8 is provided for heating the molten salt in the vicinity of the molten salt discharge port, and the heating means is disposed over the entire upper surface of the molten salt layer 51. Then, the entire upper portion of the molten salt layer 51 can be maintained in a predetermined temperature range.

[0066]

According to the present invention, since the temperature of the molten salt layer is adjusted to a predetermined range, the temperature of the molten salt layer can be lowered to lower the vapor pressure of the low-boiling substance. Volatilization of low-boiling substances can be suppressed.

When the incineration residue to be melted is charged, it is charged into the molten salt layer, so that a mixed layer in which the molten salt and the incineration residue are mixed is formed below the molten salt layer.
Heat transfer from the molten slag layer to the molten salt layer is hindered. For this reason, the temperature rise of the molten salt layer is suppressed, and the volatilization of low-boiling substances is suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an embodiment according to a melting furnace of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is a plan view showing another example of the embodiment of the melting furnace of the present invention.

FIG. 4 is a sectional view taken along the line BB in FIG. 3;

FIG. 5 is a longitudinal sectional view showing still another example of the embodiment of the melting furnace of the present invention.

FIG. 6 is a longitudinal sectional view showing still another example of the embodiment of the melting furnace of the present invention.

FIG. 7 is a longitudinal sectional view showing an example of a means for heating a molten salt near a molten salt discharge port.

FIG. 8 is a longitudinal sectional view showing another example of the means for heating the molten salt near the molten salt outlet.

FIG. 9 is a diagram showing a result of examining a relationship between an insertion depth of an incineration residue charging pipe insertion depth and a content of an insoluble component mixed into a discharged molten salt.

FIG. 10 is a schematic longitudinal sectional view showing an example of a conventional electric resistance heating type melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Melting furnace main body 11 Slag accumulation part 12 Salt accumulation part 13 Electrode 14 Electrode insertion part 15 Incineration residue charging pipe 16 Cooling device 17 Molten salt discharge port 18 Slag discharge port 19 Metal discharge port 20 Exhaust gas discharge port 21, 22, 23 Temperature Total 24a Induction heating coil 24b, 24c Electric heater 50 Incineration residue containing salts 51 Molten salt layer 51a Mixed layer 52 Molten slag layer 53 Molten metal layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Nakao 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masahiro Sudo 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Takuya Shinagawa 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (13)

[Claims] An incineration residue containing salts is melted, and the melt is retained in a melting furnace to be separated into a molten slag layer and a molten salt layer. A method for melting incineration residues containing salts, wherein the temperature of the molten salt layer is adjusted to a predetermined range. 2. The method for melting incineration residues containing salts according to claim 1, wherein the incineration residues are charged into a molten salt layer. 3. A melting furnace for melting an incineration residue containing salts, retaining the melt in a melting furnace to separate a molten slag layer and a molten salt layer, and separating and discharging the molten slag and the molten salt. An electrode rod inserted into the furnace, having an incineration residue charging pipe provided at the upper part of the furnace, the furnace body, a slag retaining portion for retaining and heating the molten slag, and on the slag retaining portion An incineration containing salt, which is an extended portion and is divided into a salt retention portion for retaining molten salt, and a means for cooling the molten salt layer is provided on an outer peripheral portion of the salt retention portion. Residue melting furnace. 4. A melting furnace for melting an incineration residue containing salts, retaining the melt in a melting furnace to separate a molten slag layer and a molten salt layer, and separating and discharging the molten slag and the molten salt, An electrode rod inserted into the furnace, and an incineration residue charging pipe provided at the upper part of the furnace, wherein the furnace body has a slag retaining section for retaining and heating the molten slag, and a cross-sectional area inside the furnace body. A furnace for melting incineration residues containing salts, wherein the furnace is divided into a salt stagnant portion that is reduced and protrudes and extends above the slag stagnant portion and stagnates the molten salt. 5. The melting furnace for salt-containing incineration residues according to claim 4, wherein means for cooling the molten salt layer is provided on an outer peripheral portion of the salt retaining section. 6. The melting furnace for salt-containing incineration residues according to claim 4, wherein a means for heating the upper portion of the molten salt layer is provided in the salt retaining section. 7. The apparatus according to claim 3, further comprising means for cooling the molten salt layer at an outer peripheral portion of a lower portion of the salt retaining section, and means for heating an upper portion of the molten salt layer.
A melting furnace for the incineration residue containing the salts according to claim 5. 8. The furnace for melting incineration residues containing salts according to claim 6, wherein means for heating the upper portion of the molten salt layer is provided on an outer peripheral portion of the salt accumulation section. 9. The furnace for melting incineration residues containing salts according to claim 6, wherein means for heating the upper part of the molten salt layer is inserted into the furnace. 10. The melting furnace for incineration residues containing salts according to claim 9, wherein the heating means inserted into the furnace is immersed in the molten salt layer. 11. The furnace for melting incineration residues containing salts according to claim 9, wherein the heating means inserted into the furnace is arranged above the molten salt layer. 12. The method according to claim 3, wherein the lower end of the incineration residue charging pipe is inserted so as to be located below the level of the molten metal when the molten salt layer is formed. A melting furnace for an incineration residue containing the salt according to any one of the above. 13. The salt according to claim 12, wherein the lower end of the incineration residue charging pipe is inserted to a position at least 20 cm deeper than the molten metal level when the molten salt layer is formed. Melting furnace for incineration residues.