JPH1046159A - Apparatus for converting polymer waste into oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to suppress the formation of crazing due to thermal stress, to improve the heat decomposition characteristics, and to suppress the long-term deposition and fixation of carbonized residues in a heat decomposition furnace by using a heat decomposition furnace for gasifying polymer wastes by heat decomposition and heating the wastes in a catalytic combustor. SOLUTION: A combustion waste gas 23 from a catalytic combustor 3 is fed into a heating furnace 2 to heat a heat decomposition furnace 1 to a specified temperature, say, about 500 deg.C. A combustion waste gas 24 leaving the exit of the furnace 2 is cooled by, e.g. cooling means, treated when it contains a noxious component, and then discharged into the atmosphere. During this time, a polymer waste 20 is fed into the furnace 1, and an agitator is actuated to agitate an agitation medium and the waste. A gas 25 resulting from the heat decomposition of the waste is cooled in a condenser 4, and a low-boiling component is condensed into an oil, which is then recovered. Meanwhile, a gas 27 comprising a noncondensible high-boiling component is burned or discharged after intoxication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an apparatus for converting polymer waste into oil.

[0002]

2. Description of the Related Art Polymer materials such as plastics are used in various types of equipment products, and the amount of waste is increasing year by year with the increase in the amount of production, which is a social problem. Currently, most polymer waste is disposed of by landfill and incineration.
However, there is a problem of a shortage of landfill sites, and in the case of incineration, there is a problem of shortening the life of the incinerator and environmental pollution due to exhaust gas and the like. In order to solve these problems, methods for recycling polymer waste and recovering energy have been studied.

[0003] One of the recycling methods for combustible substances, especially plastics, among polymer wastes is a method in which waste plastics are thermally decomposed into oil. JP-A-49-17477 and JP-A-59-17468 disclose methods of converting thermoplastic oil into oil by melting and pyrolysis, recovering the oil, and using it as fuel.
No. 9, etc. There are various methods for pyrolysis of waste plastics. One of these methods is to heat the pyrolysis tank by burning the recovered oil with a burner, and to agitate the waste plastic with a stirring member to gasify the waste plastic and oil. A method for making the conversion is disclosed in JP-A-3-285987 and the like.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
As described in the above item, in the direct flame heating method in which the bottom of the pyrolysis furnace is directly heated by the burner combustion flame provided in the heating furnace, the heating amount near the flame becomes large, and the heating temperature of the pyrolysis furnace becomes uneven. Easy to be. For this reason, the amount of heating in the vicinity of the flame becomes large, and there is a danger that the thermal decomposition furnace is likely to be cracked by thermal stress. Further, in the burner combustion, there is a problem that harmful components such as nitrogen oxides are easily discharged, and a treatment device is required, thereby increasing the treatment cost.

On the other hand, a stirring member disposed in the cracking vessel promotes melt pyrolysis while agitating the raw material waste plastic in the vicinity of the inner surface of the bottom of the cracking vessel. The waste plastic decomposed by melting and pyrolysis is turned into a residue, that is, carbonized and pressed against the inner surface of the bottom of the decomposition vessel by the stirring blade. For this reason, the carbonized residue pressed against the inner surface of the bottom of the decomposition pot is fixed in a state where it cannot be easily separated. Therefore, heat conduction is reduced and the consumption of burner heating fuel oil is increased. Further, this type of stirring blade shape has a problem that waste plastic and carbonized residue easily accumulate at the center of the stirring shaft, and waste plastic is mixed into the carbonized residue and undecomposed waste plastic remains.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for heating a pyrolysis furnace for pyrolyzing and gasifying waste plastics under heating. A high-temperature combustion exhaust gas from the catalytic combustor is supplied to a heating furnace, and the high-temperature exhaust gas indirectly heats the pyrolysis furnace. In addition, the agitation heat medium and waste plastic are unmelted under heating so that the agitation heat medium having a large surface area is provided, and the agitation heat medium and the waste plastic are combined together by an agitation blade provided with one or more blades at an acute angle or at a right angle to the agitation axis. It is intended to improve the uniform thermal decomposition characteristics by stirring.

According to the present invention, a catalytic combustor is provided outside a heating furnace of a thermal decomposition furnace, and high-temperature combustion exhaust gas from the catalytic combustor is supplied to the heating furnace. It can be heated uniformly and cracks due to thermal stress can be prevented. Further, since clean exhaust gas is generated by catalytic combustion, emission of harmful components such as nitrogen oxides can be suppressed, and the installation of a processing device is not required.

Further, since the stirring heat medium having a large surface area is stirred together with the waste plastic by the stirrer, the waste plastic can be uniformly heated and stirred, and the thermal decomposition characteristics can be improved. In addition, the carbonized residue that tends to adhere and accumulate over time is scraped off with a stirring heat medium having a large surface area to improve the releasability, so that the thermal efficiency can be improved and the fuel consumption of the catalytic combustor can be reduced. Furthermore, since the waste plastic and the carbonized residue are uniformly stirred and dispersed by the stirrer provided with the stirring blade at a right angle or an acute angle with respect to the stirring shaft and the stirring heat medium, the undecomposed waste plastic can be decomposed without remaining. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic view of a device for thermally cracking and polymerizing polymer waste according to the present invention. FIG. 2 shows a schematic diagram of a pyrolysis furnace for polymer waste.

The thermal cracking oil converting apparatus shown in FIG. 1 comprises a thermal cracking furnace 1, a heating furnace 2, a catalytic combustor 3, a condenser 4, and a catalyst 5. Other symbols are polymer waste 20, fuel 21, air 22, flue gas 23, flue gas 2 at the heating furnace outlet.
4, pyrolysis gas 25, product oil 26, and uncondensed gas 27. FIG. 2 shows details of the pyrolysis furnace 1. In addition to the configuration shown in FIG. 1, a stirrer 6 including a stirring blade 7 and a stirring shaft 8,
Further, it is composed of a stirring heat medium 9.

The operation will be described. Fuel 21 (kerosene or the like) and air 22 are supplied to the catalytic combustor 3 and burned. As the catalyst 5 of the catalytic combustor 3, for example, lanthanum
Beta alumina (La · β · Al ₂ O ₃ ) is used. The combustion exhaust gas 23 from the catalytic combustor 3 is supplied to the heating furnace 2, and the pyrolysis furnace 1 is heated to a predetermined temperature, for example, about 500 ° C. The combustion exhaust gas 24 from the outlet of the heating furnace 2 is cooled by a cooling means or the like, or when a harmful component is contained, treated and released to the atmosphere. During this time, the polymer waste 20 is supplied to the pyrolysis furnace 1, and the stirrer 6 is operated by driving a motor, whereby the stirring heat medium 9 and the polymer waste 20 are stirred. The stirrer 6 is provided with five rod-shaped stirring blades 7 having an acute angle of 45 degrees with respect to the stirring shaft 8.
The stirring heat medium 9 used has a large number of protrusions on a spherical surface. The pyrolysis gas 25 of the polymer waste 20 is cooled in the condenser 4, and low-boiling components are condensed and liquefied and recovered as oil. On the other hand, the non-condensed gas 27 of a high boiling point component which is not condensed and liquefied is burned or made harmless and exhausted.

According to the above embodiment, since the heating is performed not by the direct combustion flame but by the high-temperature exhaust gas from the catalytic combustor 3, local heating of the pyrolysis furnace 1 is eliminated, and the pyrolysis furnace can be uniformly heated. . For this reason, cracks in the pyrolysis furnace due to thermal stress can be suppressed. Further, since clean combustion can be performed by catalytic combustion, emission of harmful components such as nitrogen oxides can be suppressed, and there is no need to install a processing apparatus, which has the effect of reducing processing costs.

Further, a stirrer 6 is disposed in the pyrolysis furnace 1 at an arbitrary position without approaching the bottom of the pyrolysis furnace 1 to stir the stirring heat medium 9 having a large heating surface area.
There is an effect that the waste plastic can be uniformly heated and stirred to improve the thermal decomposition characteristics. Further, since the carbonized residue adhered to the inside of the thermal decomposition furnace 1 can be rubbed and improved by the stirring heat medium 9, the accumulation and fixation of the carbonized residue in the thermal decomposition furnace 1 over time can be suppressed. Therefore, since the thermal efficiency can be improved, the fuel consumption of the catalytic combustor 3 can be reduced. Furthermore, since the waste plastic and the carbonized residue are uniformly stirred and dispersed by the stirrer provided with the stirring blade at a right angle or an acute angle with respect to the stirring shaft and the stirring heat medium, the undecomposed waste plastic can be decomposed without remaining. effective. The stirring heat medium 9 may be any as long as it is non-melting under heating, is movable by the power of the stirrer 6, and has a large surface area.

[0015]

According to the present invention, since heating is performed with high-temperature exhaust gas from the catalytic combustor, local heating of the pyrolysis furnace is eliminated, the pyrolysis furnace can be uniformly heated, and cracks due to thermal stress can be suppressed. . Further, since the stirring heat medium having a large heating surface area is stirred by the stirrer, the waste plastic can be uniformly heated and stirred, and the thermal decomposition characteristics can be improved. Furthermore, since the agitation heat medium can suppress accumulation and fixation of the carbonization residue in the pyrolysis furnace 1 over time, there are effects such as improvement in thermal efficiency and reduction in fuel consumption of the catalytic combustor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus for thermally cracking and polymerizing polymer waste.

FIG. 2 is a schematic diagram of a pyrolysis furnace for polymer waste.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pyrolysis furnace, 2 ... Heating furnace, 3 ... Catalytic combustor, 4 ... Condenser, 5 ... Catalyst, 6 ... Stirrer, 7 ... Stirring blade, 8 ... Stirring shaft,
9: stirring heat medium.

Continued on the front page (72) Inventor Toshio Yamashita 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Shigeru Azuhata 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi R & D Co., Ltd. (72) Inventor Tomoyuki Saito 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Inside the Machinery Division, Hitachi, Ltd. No. 9-18 Inside Hitachi System Technology Co., Ltd.

Claims (3)

[Claims] 1. An apparatus for liquefying polymer waste, comprising: a pyrolysis furnace for pyrolyzing and gasifying the polymer waste under heating; and a catalytic combustor for heating the pyrolysis furnace. . 2. The process of claim 1, wherein said pyrolysis furnace comprises a stirrer for stirring the polymer waste, and a stirring medium movable by said stirrer. apparatus. 3. An apparatus for converting polymer waste into oil according to claim 2, further comprising a stirring blade provided with one or more blades at an acute angle or at a right angle to the axis of the stirring body.