JPH1112579A - Pyrolysis for preventing adhesion and solidification of polymeric substance or the like in thermal decomposition treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating method in thermal decomposition without sticking or solidifying by polymerizing thermally decomposed gas in the form of needle crystal, etc., in a discharge system or without solidifying a sublimating substance by lowering of temperature. SOLUTION: When waste plastic, etc., are heated in a thermal decomposition furnace H subjected in oxygen-free atmosphere under reduced pressure or in oxygen-free atmosphere to carry out primary thermal decomposition treatment and the thermally decomposed gas is sucked and discharged from a discharge port 2B of the furnace H, a primary thermally decomposed gas produced in the furnace H is re-heated to a high temperature higher than the primary thermal decomposition temperature in or near the discharge port 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pyrolysis treatment of waste materials such as waste plastics, in which the temperature in the pyrolysis treatment system is
If the temperature decreases due to cooling, the pyrolysis gas generated in the system will polymerize, and the sublimated material will solidify due to a decrease in the furnace temperature due to cooling, etc., and will adhere to the pipes, etc. in the system as needle crystals and solidify. The present invention relates to a processing method for preventing occurrence of a phenomenon.

[0002]

2. Description of the Related Art Conventionally, in the thermal decomposition treatment of waste plastic, if the object to be treated contains, for example, a styrene monomer or a plasticizer, the gasified substances are polymerized during the repeated thermal decomposition treatment. Or the sublimation material is solidified due to a decrease in the furnace temperature and adheres in the form of needle crystals or the like in the exhaust path, thereby reducing the exhaust efficiency and reducing the processing efficiency, or It is known that troubles such as clogging of pipes and valves constituting a system path occur.

For this reason, in the current thermal decomposition treatment of waste plastics and the like, for example, hydroquinone (hydroquinone) is added as a polymerization inhibitor, for example, in an amount of about 20 g per 1 t of processed material, that is, about 200 ppm. ,
It is not rational to perform the operation of adding the additive to the processed product every time the process is performed.

[0004]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a method in which a pyrolysis gas is polymerized in the form of needle crystals or the like in an exhaust system, or a sublimation substance is solidified by a decrease in temperature. An object of the present invention is to provide a heating method in a thermal decomposition treatment that does not cause solidification.

[0005]

In order to solve the above-mentioned problems, one aspect of the method of the present invention is to remove waste plastics and the like in a pyrolysis furnace placed in a reduced-pressure oxygen-free atmosphere or an oxygen-free atmosphere. When the primary pyrolysis gas is heated and subjected to the primary pyrolysis treatment, and the pyrolysis gas generated in the furnace is sucked and discharged from the exhaust port of the furnace, the primary pyrolysis gas generated in the furnace is exhausted or in the vicinity thereof. And reheating to a temperature higher than the primary thermal decomposition treatment temperature. Another method for achieving the above object is to perform a pyrolysis treatment by heating waste plastic or the like in a pyrolysis furnace placed in a reduced-pressure, oxygen-free atmosphere or an oxygen-free atmosphere. Then, when the heating in the furnace is stopped, the exhaust port of the pyrolysis furnace or the vicinity thereof is heated to 800 ° C. or more and about 1000 ° C., and suction and exhaust is performed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the method of the present invention will be described with reference to the drawings. FIG. 1 is a system block diagram of an example of a thermal decomposition processing apparatus to which the method of the present invention is applied.

In FIG. 1, reference numeral 1 denotes a cylindrical or basket-shaped processing vessel which is rotatably disposed inside an inner chamber 2 by a horizontal shaft 1a. An object is accommodated. Reference numeral 3 denotes an outer chamber in which the outer side of the inner chamber 2 is covered with a heat insulating wall while keeping the space 4, and a door of the inner chamber 2
A door 3a that opens and closes in conjunction with 2a
Burner 5 such as gas burner or oil burner
As a heating source, and is formed in a pyrolysis furnace H.

In the pyrolysis furnace H, 3b is a flue provided in the outer chamber 3, 3c is a cooling fan, and 3d is a temperature control valve. On the other hand, reference numeral 2b denotes an exhaust passage for the pyrolysis gas or the like provided in communication with the inner chamber 2, and reference numeral 2c denotes a residue discharge device formed in communication with the chamber 2 on the bottom side of the inner chamber 2.

Reference numeral 6 denotes a primary treatment device for the pyrolysis gas, which is connected to the exhaust passage 2b of the pyrolysis furnace and neutralizes and cleans the pyrolysis gas or separates and extracts tar from the gas.

The apparatus 6 includes a neutralization tower 6a for introducing a pyrolysis gas from an exhaust passage 2b from above, flowing the gas through a shower of a neutralizing solution and flowing the gas downward, and a neutralization tower 6a. A tank connected to the lower portion of 6a to receive the neutralizing solution, a tar separation tank 6b for separating oil and neutralizing solution in the tank, and a neutralization tower which is set up from the upper portion of the separation tank 6b. A washing tower 6c, which is a tower standing in parallel with 6a and neutralizes and cleans gas flowing out of the tar separation tank 6b with a liquid shower such as a neutralizing solution, is provided.

In the primary treatment device 6, 6d and 6d 'are shower devices provided in the neutralization tower 6a and the washing tower 6c, and 6e is a neutralizer feeding device for supplying a neutralizing solution or the like to the shower device 6d'. , 6f and 6g are circulation pumps provided in the tar separation tank 6b, 6h is a tar discharge pump, and 6j and 6k are shower pumps.
In this primary treatment device 6, the gas generated in the pyrolysis furnace via the washing tower 6c is supplied to a cyclone-type gas-liquid separation device 6i.
, The gas is supplied to a system path leading to the next blower device 7, and the liquid is connected to the tar separation tank 6b.

Numeral 8 denotes an accumulator inserted in a system between the gas-liquid separation device 6i and the blower device 7, and an accumulator 8 connected to a system on the discharge side of the blower device 7.
This is for supplying a pyrolysis gas in a stable state, and thus forms a main part of a pyrolysis apparatus for waste plastics and the like to which the method of the present invention is applied.

In the above-mentioned pyrolysis apparatus, in the pyrolysis furnace H, the processing vessel 1 in which a processed material such as waste plastic is stored.
While the is rotated, the primary pyrolysis process proceeds. That is, the burner 5 is ignited to heat the inside of the space 4 of the outer chamber 3 and, at the same time, the inside of the inner chamber 2 is sucked by the blower device 7, for example, at about 300 ° C. or lower depending on the target material. Heat to the following temperature, or 300 ~ 500
By heating to a temperature of about ° C., the inside of the inner chamber 2 is heated to a required temperature and held therein, and the processed material such as waste plastic stored in the rotating processing container 1 is primarily thermally decomposed. It is.

The processed material in the processing vessel 1 is thermally decomposed by the above-mentioned heating, and the generated pyrolyzed gas is led out of the furnace through the exhaust path 2b by the action of the suction force of the blower device 7, and is then discharged to the primary processing device 6 The odor component contained in the gas is thermally decomposed, and the combustible component is burned and released out of the system.

As described above, when the primary thermal decomposition treatment of the processed material in the processing container 1 proceeds, various substances constituting the processed material are gasified, but these gases are newly bonded to each other to form foreign substances. Often produced by polymerization. When the thermoelectric decomposition process is completed in such a situation, the burner 5 is extinguished, the cooling fan 3c is driven, the temperature control valve 3d is opened, and the inside of the furnace is cooled to prepare for the next thermal decomposition process of the processed product. . However, when the temperature in the furnace decreases, for example, polymerized phthalic anhydride generated from the processed material solidifies and adheres to the exhaust system including the exhaust system 2b, or the gasified styrene monomer polymerizes and solidifies. It is known that they adhere to the pipes as crystalline crystals or the like, increase the gas flow resistance there, or clog the exhaust system. In the prior art, in order to prevent this needle-like crystal and the like from being generated and attached to the inside of a pipe or the like,
About 200 ppm of hydroquinone is added as a polymerization inhibitor.

In the present invention, in order to omit the addition of the polymerization inhibitor, an electric heating means 13 such as a nichrome wire heater is provided in the exhaust passage 2b made of, for example, stainless steel, and the primary thermal decomposition step is performed. The pyrolysis gas generated therein is again heated at a temperature higher than the heating temperature at the time of the primary pyrolysis to perform secondary pyrolysis, or at the time when the heating in the pyrolysis furnace H is completed or thereafter. Exhaust passage when cooling begins
The inside of 2b was heated and held so as not to lower the temperature therein, and this was sucked and evacuated by the blower device 7. The heating temperature in this case depends on the heating means 13
It is preferred that the exothermic temperature is about 800 ° C. to 1100 ° C. or higher. The reason is that the properties of the stainless steel material forming the exhaust path 2b change around about 650 ° C., and the surface temperature of the exhaust path 2b itself is increased by setting the temperature of the heating means 13 to about 800 to 1100 ° C. or more. The 650
C. or less, for example, about 520.degree. After the heating for the primary pyrolysis treatment is completed, the heating is performed in combination with the driving of the blower device 7.

As described above, according to the present invention, the pyrolysis gas generated during the primary pyrolysis is reheated at a higher temperature than the primary pyrolysis in the exhaust passage 2b to perform the secondary pyrolysis, or After the completion of the heating, a heating step for the exhaust path is added, so that the gasification of the generated pyrolysis gas is further promoted during the pyrolysis processing step, and the inside of the furnace is heated after the heating for the pyrolysis processing ends. Due to the lowering of the temperature, clogging of the gas discharge system such as acicular crystallization of styrene monomer contained in the product gas remaining in the furnace can be prevented, and therefore, the addition of a polymerization inhibitor becomes unnecessary. In addition, the efficiency of the thermal decomposition process itself is improved.

[0018]

Industrial Applicability The present invention is as described above, and waste plastics and the like are subjected to primary pyrolysis treatment in a pyrolysis furnace placed in a reduced-pressure oxygen-free atmosphere or an oxygen-free atmosphere, and formed in the furnace. Various kinds of pyrolysis gas generated in the furnace or a gas generated by combining specific gases among them when the pyrolysis gas is sucked and discharged from the exhaust port of the furnace The polymerized material is re-heated at, for example, 800 ° C. or higher in the exhaust port or in the vicinity thereof so as to be thermally decomposed again. For example, it is possible to prevent the generation of a substance, for example, a needle crystal or the like that adheres and solidifies to the exhaust passage, thereby increasing the thermal decomposition efficiency.

[Brief description of the drawings]

FIG. 1 is a system block diagram of an example of a pyrolysis apparatus to which the method of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing container 2 Inner chamber 2a Door 2b Exhaust passage 2c Residue discharger 3 Outer chamber 3a Door 3b Flue 3c Cooling fan 3d Temperature control valve 4 Space 5 Gas burner 6 Primary treatment device of pyrolysis gas 6a Neutralization tower 6b Separation tank 6c Washing tower 6d Shower device 6e Neutralizer charging device 6f, 6g Circulation pump 6h Tar discharge pump 6i Gas-liquid separation device 6j, 6k Shower pump 7 Blower device 8 Accumulator 9 Deodorizing device 9a Deodorizing tower 9b Gas burner H Pyrolysis Furnace

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 26

Claims (3)

[Claims] A waste plastic or the like is heated and subjected to a primary pyrolysis treatment in a pyrolysis furnace placed in a reduced-pressure oxygen-free atmosphere or an oxygen-free atmosphere, and a pyrolysis gas generated in the furnace is supplied to the furnace. A polymerization in a pyrolysis treatment, wherein the primary pyrolysis gas generated in the furnace is reheated to a high temperature equal to or higher than a primary pyrolysis temperature in the exhaust port or in the vicinity thereof when the gas is sucked and discharged from an exhaust port. Pyrolysis treatment method to prevent solidification of substances. 2. The temperature of the primary thermal decomposition treatment is about 300 ° C. or less, or about 300 ° C. to 500 ° C., and the temperature of the secondary thermal decomposition treatment is about 800 ° C. or more. A thermal decomposition treatment method for preventing adhesion and solidification of a polymer substance or the like in the thermal decomposition treatment according to claim 1. 3. When a waste plastic or the like is heated in a pyrolysis furnace placed in a reduced-pressure oxygen-free atmosphere or an oxygen-free atmosphere to perform a pyrolysis process, and when the process is completed and heating in the furnace is stopped, 800 ° C. or higher at the exhaust port of the pyrolysis furnace or its vicinity
A pyrolysis method for preventing adhesion and solidification of a polymer substance or the like in a pyrolysis process, wherein the material is heated to about 000 ° C and suctioned and exhausted.