JPH10279948A - Pyrolysis furnace for industrial waste - Google Patents

Abstract

(57) [Summary] [Object] To provide a pyrolysis furnace for industrial waste that can make the temperature distribution in the pyrolysis chamber uniform. An industrial waste pyrolysis furnace according to the present invention includes a pyrolysis chamber for charging industrial waste, an outer wall having heat insulation provided surrounding the pyrolysis chamber, and heating the pyrolysis chamber from outside. In a pyrolysis furnace for industrial waste having a heating means for performing heat treatment, a predetermined vertical portion is provided protruding downward from the bottom of the pyrolysis chamber 11 to form a bottom heat retention space 11d. An enclosing member 11a having a length, and a pyrolysis chamber 1 provided between the bottom of the pyrolysis chamber 11 and the heating means 17.
1 a flame shut-off member 11 for preventing the flame from directly hitting the bottom
c, and a space forming member 11b provided so as to have a downward opening around the thermal decomposition chamber 11 to form the side heat retention space 11e. It is characterized by.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyrolysis furnace for a thermal decomposition apparatus for industrial waste, and more particularly to a thermal decomposition furnace for storing industrial waste, which has a substantially uniform temperature distribution in the pyrolysis chamber. The present invention relates to a pyrolysis furnace for industrial waste that can be decomposed.

[0002]

2. Description of the Related Art At present, the amount of industrial waste such as resin-based waste, garbage, medical waste and used disposable diapers from cities, factories, general households, hospitals and the like is extremely large. Has become. And the treatment of these industrial wastes
Each is performed in the following manner.

[0003] First, there is an incineration treatment. This is a method in which each industrial waste is incinerated at around 1000 degrees Celsius in a combustion furnace for disposal. This processing is the most general processing method.

[0004] As a second processing method, there is a dumping processing. This is a processing method in which each industrial waste is subjected to a volume reduction treatment such as finely pulverizing and compressing, and then stored in a container, a bag, or the like, and dumped in a dumping land or buried in a landfill.

[0005] However, industrial waste containing a chlorine-based polymer compound such as vinyl chloride is treated under conditions exceeding the thermal decomposition temperature of vinyl chloride to generate hydrogen chloride gas, which causes pollution. Temperature below thermal decomposition temperature (150 ℃
Under the following conditions, the melt-solidification treatment was performed. Also, the melting point of vinyl chloride (120 ° C.) such as polypropylene (melting point 180 ° C.) and polyethylene terephthalate (melting point 250 ° C.)
(-130 ° C.), the treatment was performed by heating to these melting points and charging and recovering hydrogen chloride generated at that time by adding calcium salts (eg, slaked lime).

However, in the case of the first incineration treatment, there is a problem that toxic gas, black smoke and dust are generated, and pollutants are scattered around the incineration treatment plant. In addition, there is a problem that the incineration apparatus is seriously damaged due to the generation of high heat and high-temperature gas by incineration. Further, there is a problem that harmful substances are left as residues, and harmful substances are included in fly ash and generated gas. In this case,
In order to collect the generated gas and dust, a method of spraying water into the exhaust gas in a shower shape may be used.However, since the water is sprayed in a shower shape, the process can be performed under reduced pressure. However, there is also a problem that the odor leaks from the exhaust gas.

Further, in the case of the second dumping treatment, there is a problem that secondary pollution such as the destruction of the dumping land itself or contamination of groundwater by waste occurs.

[0008] Particularly, in the treatment of industrial waste containing hydrogen chloride, highly toxic, teratogenic and highly carcinogenic organic hydrogen chloride compounds such as dioxin and polychlorinated dibenzofuran are generated, and the effect on the ecology is also a problem. Had become.

In view of the above problems, the present applicant has proposed a method and an apparatus for dehydrochlorinating industrial waste, which qualify and efficiently treat industrial waste without causing pollution.
Invented a method for treating industrial waste containing organic matter and applied for a patent.

[0010]

FIG. 6 shows an apparatus for thermal decomposition of industrial waste invented by the present applicant. The pyrolysis apparatus 1 for industrial waste is generally composed of a pyrolysis furnace 10, a gas diffusion device 20, a tar removal device 30, and a neutralization tank 50.
, A decompression pump 60, and a combustion deodorization device 70.

A pyrolysis chamber 11 provided in a pyrolysis furnace 10
The industrial waste put into the furnace is decompressed to below the atmospheric pressure by the decompression pump 60 and heated from the bottom of the pyrolysis chamber 11.
By heating, industrial waste is dehydrated and pyrolyzed. The gas generated by the thermal decomposition recovers harmful substances in the gas diffusion device 20, the tar removal device 30, and the neutralization tank 50, respectively. The finally remaining gas is burned in the combustion deodorizing device 70 to be thermally decomposed.

Most of the pyrolyzed industrial waste contains only carbon components. Subsequent processing can be easily performed. Further, the use of the thermal decomposition treatment apparatus enables safe and pollution-free treatment of industrial waste.

In order to completely decompose all of the industrial waste, it is necessary to heat the industrial waste at a uniform temperature for a certain period of time. For that purpose, the temperature distribution in the pyrolysis chamber 11 is
Must be uniform. If the temperature distribution is non-uniform, thermal decomposition of a different substance from the target substance may start depending on the location, or the target substance may not be completely decomposed and the process may be completed with harmful substances remaining become.
Further, the thermal decomposition chamber 11 may be damaged by thermal distortion due to a temperature difference. However, since the thermal decomposition chamber 11 is heated from the outside, it is difficult to control the temperature while making the internal temperature distribution uniform.

When the thermal decomposition chamber 11 is heated, the thermal decomposition chamber 11 is directly exposed to the heating means, so that the thermal decomposition chamber must be made of a material having heat resistance. However, such materials are generally unsuitable for use in the thermal decomposition chamber 11 because many of them have a poor heat transfer coefficient.

An object of the present invention is to provide an industrial waste pyrolysis furnace capable of uniformly adjusting the temperature distribution in a pyrolysis chamber.

Another object of the present invention is to provide an industrial waste which can heat a pyrolysis chamber without directly exposing it to a flame of a burner, even when a burner is used as a heat source for heating the pyrolysis chamber. To provide a pyrolysis furnace.

As a result, it is an object of the present invention to provide a pyrolysis furnace for industrial waste that can efficiently transfer heat into a pyrolysis chamber.

[0018]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a pyrolysis chamber for charging industrial waste, thermally decomposing the industrial waste in a sealed and reduced pressure, and surrounding the pyrolysis chamber. In an industrial waste pyrolysis furnace having an outer wall having heat insulation and a heating means provided between the pyrolysis chamber and the outer wall for heating the pyrolysis chamber from the bottom, it corresponds to a low-temperature section in the pyrolysis chamber. A thermal decomposition furnace for industrial waste characterized by forming a heat retention space at a designated position.

According to a second aspect of the present invention, there is provided a thermal decomposition chamber in which industrial waste is charged and thermal decomposition of the industrial waste is hermetically sealed and reduced pressure, an outer wall having heat insulation provided surrounding the thermal decomposition chamber, and In an industrial waste pyrolysis furnace provided between a pyrolysis chamber and an outer wall and having heating means for heating the pyrolysis chamber from the bottom, the pyrolysis chamber is provided continuously around the bottom of the pyrolysis chamber and protrudes downward. Thermal cracking of industrial waste, comprising a provided enclosure member having a predetermined vertical length provided, wherein a space surrounded by the enclosure member and the bottom of the pyrolysis chamber forms a bottom heat retention space. Provide a furnace.

According to a third aspect of the present invention, there is provided a thermal decomposition chamber in which industrial waste is charged and thermal decomposition of the industrial waste is hermetically sealed and reduced pressure, an outer wall having heat insulation provided surrounding the thermal decomposition chamber, and In an industrial waste pyrolysis furnace provided between a pyrolysis chamber and an outer wall and having heating means for heating the pyrolysis chamber from the bottom, a flame provided between the bottom of the pyrolysis chamber and the heating means Provided is a pyrolysis furnace for industrial waste, which is provided with a blocking member.

According to a fourth aspect of the present invention, in the industrial waste pyrolysis furnace according to the first or second aspect, a flame blocking member provided between the bottom of the pyrolysis chamber and the heating means is provided. It is characterized by comprising.

According to a fifth aspect of the present invention, in the industrial waste pyrolysis furnace according to the third or fourth aspect, the flame blocking member is a ceramic plate having heat resistance. .

According to a sixth aspect of the present invention, there is provided a thermal decomposition chamber in which industrial waste is charged and thermal decomposition of the industrial waste is hermetically sealed and reduced pressure, an outer wall having heat insulation provided surrounding the thermal decomposition chamber, and In an industrial waste pyrolysis furnace having a heating means provided between the pyrolysis chamber and the outer wall and having a heating means for heating the pyrolysis chamber from the bottom, a recess opened in the direction is formed circumferentially around the four circumferences of the pyrolysis chamber. A pyrolysis furnace for industrial waste characterized by being provided with a space forming member that is provided in a row and that defines a recess on the lower side, wherein the recess forms a side heat retention space. provide.

According to a seventh aspect of the present invention, in the industrial waste pyrolysis furnace according to any one of the first to fifth aspects, a recess opened in the direction is circumferentially connected to four circumferences of the pyrolysis chamber. And a space forming member that defines a recess below the recess, and the recess forms a side heat retention space.

According to an eighth aspect of the present invention, in the industrial waste pyrolysis furnace according to the sixth or seventh aspect, a plurality of space forming members are provided in a height direction of the thermal decomposition chamber. A pyrolysis furnace for industrial waste.

According to a ninth aspect of the present invention, in the industrial waste pyrolysis furnace according to any one of the first to eighth aspects, an intermediate partition is provided between the pyrolysis chamber and an outer wall.

According to a tenth aspect of the present invention, in the industrial waste pyrolysis furnace according to any one of the first to ninth aspects, an exhaust port provided on a side portion of the outer wall near the inner bottom surface of the outer wall is provided. A pyrolysis furnace for industrial waste, comprising:

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of an apparatus for thermally decomposing industrial waste will be described. FIG. 6 shows an apparatus for thermally decomposing industrial waste. The industrial waste thermal decomposition treatment apparatus 1
Schematically, the pyrolysis furnace 10, the gas diffusion device 20, the tar removal device 30, the neutralization tank 50, and the vacuum pump 60
And a combustion deodorizing device 70.

The thermal decomposition furnace 10 is a device for heating and thermally decomposing industrial waste. First, industrial waste is put into a pyrolysis chamber 11 provided in a pyrolysis furnace 10.
Next, the thermal decomposition chamber 11 is sealed, and the pressure inside the thermal decomposition chamber 11 is reduced to a pressure lower than the atmospheric pressure by the vacuum pump 60. Then, the pyrolysis chamber 11 is heated from the outside in an oxygen-free state. Pyrolysis chamber 11
By reducing the pressure inside, the toxic gas is prevented from flowing out. Further, by setting the oxygen-free state, chlorine gas generated by thermal decomposition can be prevented from being combined with oxygen in the thermal decomposition chamber 11 to generate highly toxic dioxin. In the thermal decomposition, the water contained in the industrial waste is dehydrated by temporarily maintaining the temperature at about 100 to 160 ° C. After the dehydration is completed, the pyrolysis chamber 11 is heated to a predetermined pyrolysis temperature to pyrolyze the industrial waste.

The gas generated by the thermal decomposition is collected in the gas diffusion device 20. The gas diffusion device 20 is a device for separating predetermined components in gas generated by thermal decomposition. The gas diffusion device 20 blows gas into a water tank having a stirring device filled with a predetermined solution to dissolve and collect the components of the gas in the solution. By filling the water tank with water, chlorine gas, which is a water-soluble component of the gas, can be separated. Further, the water in the water tank becomes hydrochloric acid due to the chlorine gas dissolved in the water tank. Hydrochloric acid whose concentration has exceeded a certain level
It is discharged to the collection tank 40. The discharged hydrochloric acid is neutralized with an alkaline substance such as sodium hydroxide, calcium hydroxide, etc., and recovered as harmless sodium chloride and calcium chloride.

The tar removing device 30 is a device for separating tar contained in the pyrolysis gas. The tar removing device 30 collects the tar content floating on the water surface of the water tank of the diffusion device 20. The neutralization tank 50 blows a pyrolysis gas into a water tank filled with a predetermined solution to dissolve and recover the components in the solution. A water-soluble gas component that cannot be completely recovered by the gas diffusion device 20 may be recovered, or a solvent that can dissolve and recover another specific gas component may be added. Since the pyrolysis gas finally left is a hydrocarbon-based gas such as methane gas or ethane gas, it is self-burned by the combustion deodorizer 70 to thermally decompose the odor component.

Next, an industrial waste pyrolysis furnace according to the present invention will be described based on a preferred embodiment shown in the drawings. FIG. 1 is a sectional view of an embodiment of the industrial waste pyrolysis furnace according to the present invention. The thermal decomposition furnace 10 is for thermally decomposing industrial waste by heating it in an oxygen-free state in a container reduced in pressure to below atmospheric pressure. The pyrolysis furnace 10
As shown in FIG. 1, the thermal decomposition chamber 11, an outer wall 13 surrounding the thermal decomposition chamber 11,
And a burner 17 for heating. An intermediate partition 15 is provided between the thermal decomposition chamber 11 and the outer wall 13. A certain space is provided between the thermal decomposition chamber 11 and the intermediate partition 15 and between the intermediate partition 15 and the outer wall 13 so that the gas flow path 12 is provided.
a and 12b are formed.

The air heated by the burner 17 flows from the bottom of the pyrolysis chamber 11 to the surroundings and rises in the gas flow path 12a. Then, from the upper part of the thermal decomposition chamber 11, the intermediate partition 15
Is discharged from the opening 15a provided at the top of the slab. The discharged air moves along the ceiling of the outer wall 13, descends along the gas flow path 12a, and is discharged from the exhaust port 18 provided at the bottom of the pyrolysis furnace 10. By providing the intermediate partition 15, high-temperature air can be convected from the inside to the outside of the intermediate partition 15. Thus, the heat exchange between the inside and the outside of the intermediate partition 15 allows the inside temperature to be uniform.

Further, by providing the exhaust port at the bottom of the pyrolysis furnace 10, the air with reduced temperature can be naturally discharged. Even without the intermediate bulkhead 15, the air above is
The same effect can be seen because it is lowered by being cooled.

The thermal decomposition chamber 11 may be made of any material having excellent corrosion resistance and heat resistance and good thermal conductivity. In this embodiment,
SUS316L, which is an inexpensive metal material, is used. However, when the bottom of the pyrolysis chamber 11 made of SUS316L is directly heated by applying the flame of the burner 17, SUS3
In the case of 16L, the immovable body cannot be maintained at around 650 ° C., and the bottom plate is wavy and deformed. Therefore, in order not to apply the flame of the burner 17 directly to the bottom plate of the SUS316L, it is preferable to provide a ceramic board 11c having excellent heat resistance between the burner 17 and the bottom plate at an appropriate position from the bottom plate. By providing the ceramic board 11c, a bar is directly provided on the bottom plate of the pyrolysis chamber 11.
The heating can be performed without applying the flame of the corner 17.

It is necessary to efficiently transmit the heat of the burner 17 into the pyrolysis chamber 11. In the present embodiment, a bottom heat retention space 11d and a side heat retention space 11e for temporarily storing the air heated by the burner 17 are provided on the bottom surface and the periphery of the thermal decomposition chamber 11.

The bottom heat retention space 11d is a space surrounded by a plate 11a provided to project downward by a predetermined vertical length along the periphery of the bottom plate of the thermal decomposition chamber 11. Further, the side heat retention space 11 e is provided at a predetermined height along the periphery of the thermal decomposition chamber 11. In this embodiment, the L-shaped section steel 11b is attached so as to open toward the bottom of the pyrolysis chamber 11. A plurality of side heat retention spaces 11e can be provided as needed.

By providing the bottom heat retention space 11d and the side heat retention space 11e, a certain amount of high-temperature air can be temporarily retained, so that heat can be efficiently transmitted to the thermal decomposition chamber 11. it can. Also, the bottom heat retention space 11
The temperature distribution in the thermal decomposition chamber 11 can be made uniform by adjusting the volume of d, the number, volume, and mounting position of the side heat retention spaces 11e.

The outer wall 13 has a heat insulating structure so as not to release internal heat. As a heat insulating method, it is sufficient that the surface of the outer wall 13 can be insulated from the inside of the high-temperature furnace to such an extent that it can be touched directly by hand. In the present embodiment, the outer wall 13 has a triple structure in which the glass wall 13b is interposed between the refractory bricks 13a. Further, since the temperature of the upper part of the furnace and the vicinity of the burner 17 is likely to be high, the thickness of the refractory brick 13a and the glass wall 13b may be increased to enhance the heat insulating effect more than other parts.

The burner 17 is provided at the bottom of the pyrolysis furnace 10. In this embodiment, the furnace is heated by burning propane gas, city gas, heavy oil, and the like. Of course, you may heat using electricity.

When the industrial waste heated in the thermal decomposition chamber 11 reaches a predetermined temperature, it is thermally decomposed and the components of the industrial waste are gasified. The generated pyrolysis gas is transported to the next step through a discharge pipe 19 connected to the upper part of the pyrolysis chamber 11.

Next, the verification results of the heat retention space and the ceramic board of the flame blocking plate provided at the bottom of the industrial waste thermal decomposition chamber according to the present invention will be described. FIG. 2 is a schematic diagram showing a temperature measurement position of a pyrolysis furnace for industrial waste. 3 to 5 are diagrams showing the results of measuring the temperature of each part of the pyrolysis furnace when the length L of the plate member forming the heat retaining space in FIG. 2 is set to 0, 10, and 20 cm.

The verification was carried out in the pyrolysis furnace shown in FIG. 2 with no industrial waste. The portion representing the transient state in the diagram shows the temperature rise process in each measurement portion up to the set temperature. The part representing the steady state after the temperature raising process indicates the steady operation process after the temperature reaches the set temperature.

The measurement parts of the pyrolysis furnace are as follows: 1. the entrance of the exhaust port of the outer wall 13, 2. the inside of the pyrolysis chamber 11, 3. the upper part outside the pyrolysis chamber 11, and 6. the thermal It is in the stay space 11d. First, FIG. 3 shows a temperature change of each measurement portion when the pyrolysis furnace is operated at L = 0 cm. Heat retention space 11
In a pyrolysis furnace having no d, the temperature inside the pyrolysis chamber 11 changes 2.
It can be seen that fluctuates greatly. That is, the temperature 3. outside the thermal decomposition chamber 11 is directly the temperature 2. inside the thermal decomposition chamber 11.
Is affecting.

Next, FIG. 4 shows a temperature change of each measurement portion when the pyrolysis furnace is operated at L = 10 cm. The temperature 6. in the heat retention space 11d indicates a temperature substantially equal to the temperature of the other portions, and the temperature inside the thermal decomposition chamber 11 in response to a steady state change of the temperature 3. outside the thermal decomposition chamber 11. It can be seen that the fluctuation range of the temperature in the steady state of 2. is a small value.
It can be seen that the temperature 2. inside the pyrolysis chamber 11 is kept substantially constant.

Finally, FIG. 5 shows a temperature change of each measurement portion when the pyrolysis furnace was operated at L = 20 cm. The temperature 6. of the portion in the heat retention space 11d has transitioned at an extremely high value compared to the temperature of the other portions. The fluctuation in the steady state at the temperature 1.2.3. Indicates a fluctuation width larger than the fluctuation of the temperature 6. in the heat retaining space 11d. This is the heat retention space 11
This is because heat is concentrated on the bottom of the thermal decomposition chamber 11 because the volume in d is too large.

By providing the ceramic board 11c, it was confirmed that the temperature 6. in the heat retaining space 11d did not exceed 650 ° C. It can be seen that it is effective to provide a ceramic board 11c between the bottom of the pyrolysis chamber 11 and the burner 17 in order to prevent thermal deformation of the pyrolysis chamber 11.

[0048]

The industrial waste pyrolysis furnace of the present invention can control the volume of the bottom heat retention space, the number, the volume, and the mounting position of the side heat retention spaces. Thereby, the inflow of heat from the periphery of the thermal decomposition chamber can be adjusted to make the temperature distribution in the thermal decomposition chamber uniform.

Further, by providing a ceramic board which is a flame blocking plate through a predetermined space at the bottom of the thermal decomposition chamber, the flame can be heated without directly hitting the thermal decomposition chamber. Thereby, the thermal decomposition chamber can be made of inexpensive stainless steel having a good heat transfer coefficient. As a result, heat transfer to the pyrolysis chamber can be promoted while preventing thermal distortion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of an industrial waste pyrolysis furnace according to the present invention.

FIG. 2 is a schematic diagram showing a temperature measurement position of an industrial waste pyrolysis furnace.

FIG. 3 is a diagram showing temperature measurement results of each part of a pyrolysis furnace when a length L of a plate member forming a heat retaining space in FIG. 2 is set to 0 cm.

4 is a diagram showing temperature measurement results of each part of a pyrolysis furnace when a length L of a plate member forming a heat retention space in FIG. 2 is set to 10 cm.

FIG. 5 is a diagram showing temperature measurement results of each part of the pyrolysis furnace when the length L of the plate member forming the heat retention space in FIG. 2 is set to 20 cm.

FIG. 6 is a schematic diagram of an apparatus for thermally decomposing industrial waste.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Thermal decomposition apparatus 10 Thermal decomposition furnace 11 Thermal decomposition chamber 11a plate, 11b type steel, 11c ceramic board
11d Bottom heat retention space, 11e Side heat retention space 12a, 12b Gas flow path 13 Outer wall 13a Firebrick, 13b Glass wool 15 Intermediate partition wall 15a Opening 17 Burner 18 Exhaust port 19 Discharge pipe 20 Gas diffusion device Reference Signs List 30 tar removal device 40 treatment tank 50 neutralization tank 60 decompression pump 70 combustion deodorization device

Claims (10)

[Claims] 1. A thermal decomposition chamber for introducing industrial waste and thermally decomposing the industrial waste under a closed and reduced pressure, an outer wall having heat insulation provided surrounding the thermal decomposition chamber, and the thermal decomposition chamber. In an industrial waste pyrolysis furnace provided between the outer wall and a heating unit for heating the pyrolysis chamber from the bottom, a heat retention space is formed at a position corresponding to a low-temperature portion in the pyrolysis chamber. A pyrolysis furnace for industrial waste. 2. A thermal decomposition chamber for introducing industrial waste and thermally decomposing the industrial waste under a closed and reduced pressure, an outer wall having heat insulation provided surrounding the thermal decomposition chamber, and the thermal decomposition chamber. In an industrial waste pyrolysis furnace provided between the outer wall and a heating means for heating the pyrolysis chamber from the bottom, the pyrolysis furnace is provided so as to protrude downward around the bottom of the pyrolysis chamber. An enclosure member having a predetermined vertical length, wherein a space surrounded by the enclosure member and the bottom of the pyrolysis chamber forms a bottom heat retention space. Pyrolysis furnace. 3. A thermal decomposition chamber into which industrial waste is charged and thermally decomposed the industrial waste in a sealed and reduced pressure, an outer wall provided with heat insulation surrounding the thermal decomposition chamber, and the thermal decomposition chamber. In an industrial waste pyrolysis furnace provided between the outer wall and a heating means for heating the pyrolysis chamber from the bottom, a flame provided between the bottom of the pyrolysis chamber and the heating means A thermal decomposition furnace for industrial waste, comprising: a blocking member. 4. The pyrolysis furnace for industrial waste according to claim 1, further comprising: a flame shut-off member provided between a bottom of the pyrolysis chamber and the heating means. A pyrolysis furnace for industrial waste. 5. The thermal decomposition furnace for industrial waste according to claim 3, wherein the flame shut-off member is a heat-resistant ceramic plate. Furnace. 6. A thermal decomposition chamber into which industrial waste is charged and thermally decomposed the industrial waste in a closed and reduced pressure, an outer wall having heat insulation provided surrounding the thermal decomposition chamber, and the thermal decomposition chamber. In an industrial waste pyrolysis furnace having heating means provided between the outer wall and the bottom for heating the pyrolysis chamber from the bottom, a downwardly open recess is formed in a circumferential direction around four circumferences of the pyrolysis chamber. A space forming member that is provided in series and that defines a recess below it, wherein the recess forms a side heat retention space; Furnace. 7. The industrial waste thermal decomposition furnace according to claim 1, wherein a downwardly opened recess is provided circumferentially continuously around four circumferences of the thermal decomposition chamber. A space forming member defining a lower recess, wherein the recess forms a side heat retention space. 8. The industrial waste thermal decomposition furnace according to claim 6, wherein a plurality of the space forming members are provided in a height direction of the thermal decomposition chamber. Waste pyrolysis furnace. 9. The pyrolysis furnace for industrial waste according to claim 1, further comprising an intermediate partition wall between the pyrolysis chamber and the outer wall. . 10. The thermal decomposition furnace for industrial waste according to claim 1, further comprising an exhaust port provided on a side portion of the outer wall close to an inner bottom surface of the outer wall. Pyrolysis furnace for industrial waste.