JPS6015674B2 - Pyrolysis method and equipment for polyolefin plastic waste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for thermally decomposing polyolefin plastic waste to obtain liquid hydrocarbon oil useful as a raw material for fuel.

Polyolefin plastics, which account for approximately 50% of the total thermoplastic plastic production in Japan, have a wide range of uses, from daily necessities and agricultural materials to industrial parts, and are closely related to our daily lives.

However, although used waste plastics are incinerated or recycled, the majority of them are simply discarded.

The amount accumulated is gradually increasing, and its disposal has become a socially important issue. If such waste plastics can be recycled as fuel or industrial materials by some means, it will lead to resource and energy conservation, which will be of great significance in our resource-poor country.

So far, there have been reports on the method of recovering hydrocarbon oil by thermally decomposing bamboo blind plastic, but there are polymers with a low degree of polymerization that are produced as by-products during the polymer manufacturing process, and polystyrene that easily becomes oil by thermal decomposition. Limited to plastics. However, when polyolefin plastics are simply thermally decomposed, that is, when they are thermally decomposed without using any catalyst, a product with a wide molecular weight distribution range from carbon number distribution to group C is obtained, and this product is a wax at room temperature. Because of this, there are limits to how it can be used, and if it is simply pyrolyzed, there are problems with the pyrolysis equipment due to the generation of carbon and the closure of piping. Therefore, the current pyrolysis technology is It is extremely difficult to thermally decompose polyolefin plastics. Therefore, there is a strong demand for a technology that can thermally decompose POIJ olefin plastics using a simple method and equipment, and that can yield a liquid product at room temperature.

This invention was developed as a result of repeated studies to develop a method and apparatus for thermally decomposing polyolefin plastic waste that can yield liquid hydrocarbon oil useful as fuel and raw materials. Alumina/iron oxide type, alumina/lotus acid type,
The inventors have discovered that high-quality hydrocarbon oil can be obtained by passing it through a silicic acid/iron oxide catalyst layer and re-thermal decomposition, leading to the creation of this invention.

According to this invention, polyolefin plastic waste is thermally melted and then thermally decomposed by heating in the range of 440 to 500°C, and the vaporized products generated by the thermal decomposition are
A secondary thermal decomposition treatment is carried out by passing through a catalyst bed of particle sizes 1 to 15 heated to 50 to 470 qo.

In the method of this invention, the thermal decomposition of polyolefin plastic waste is carried out at a temperature within the range of 440 to 50 psi, because if it is carried out outside this temperature range, the rate of oil production will be slow and the yield of the oil produced will be low. This is because it decreases.

Further, the catalyst used in this invention is an alumina/iron oxide based catalyst, such as a 500qo calcined product of alumina/iron oxide,
The catalyst used is an alumina/silicic acid based catalyst, a silicic acid/iron oxide based catalyst, such as zeolite, and has a particle size of 1 to 15 ribs, preferably about 1 mm.

The reason why the particle size is set to 15 cells or less is to increase the catalysis between the vaporized product and the catalyst, and the reason why the particle size is set to 1 cell or more is to form voids in the catalyst layer through which gas can pass. be.

Further, if the temperature of the catalyst layer is 350° C. or lower, thermal decomposition is insufficient and wax adheres to the catalyst layer, and if the temperature is 470 qo or higher, thermal decomposition proceeds too much and carbon adheres to the catalyst layer.

On the other hand, in the temperature range of 350 to 470 qo, the molecular weight distribution range is narrow, and high-grade hydrocarbon oil can be obtained at room temperature. For example, carbon number distribution C5 obtained by pyrolysis
~C42 wide molecular weight distribution products are 350-47
Carbon number distribution C5 by passing through the catalyst layer at 0°C
The produced oil has a molecular weight distribution range of ~C24, C5 to C29.

This is because the vaporized products of thermal decomposition pass through the catalyst layer, causing isomerization and changing the composition ratio. Comparing this in terms of average molecular weight, thermal decomposition without a catalyst layer has a range of 245 to 285, while re-decomposition through a catalyst layer results in a range of 135 to 190, which means that the molecular weight distribution range is narrower. Since it is biased toward low molecular weight, it is suitable as a fuel or an industrial raw material.

The polyolefin plastic waste used as the V supply material in this invention includes polyethylene, polypropylene,
In addition to olefin-based homopolymers such as polybutylene, olefin-based copolymer plastics and low-profile polyethylene are also included.

According to this invention, it is possible to produce fuel and industrial raw materials using polyolefin plastic waste that has been discarded and left as raw material, resulting in effective use of resources and prevention of pollution, making it a very useful technology. Become.

Hereinafter, the apparatus of the present invention will be explained based on the illustrated embodiments.

1 is a thermal decomposition reaction apparatus for polyolefin plastic waste, and the thermal decomposition reaction apparatus 1 includes a raw material supply section 2, a thermal decomposition reaction section 3, and a catalyst layer reaction section 4 provided above it.
A raw material transfer means 5 such as a screw feeder is provided at the bottom of the raw material supply section 2 with its end facing the upper part of the pyrolysis reaction section 3. Furthermore, a thermometer 6 consisting of a thermocouple, etc. is inserted into the catalyst layer, and its tip is placed at an appropriate position in the molten raw material inside the thermal decomposition reaction section 3. A level meter 7 is inserted as shown in the figure, and a thermometer 8 composed of a thermocouple or the like is inserted so that its tip is in the gas phase.

A heater is provided around the outer periphery of the pyrolysis reactor 1, and this heater heats the inside of the raw material supply section 2 into which the polyolefin plastic waste is fed to, for example, 360qC, and the screw feeder 5 turns the molten polyolefin plastic into The inside of the thermal decomposition reaction section 3 to which is supplied is 440
The inside of the catalyst layer reaction section 4 is set in a temperature range of 350 to 470 qo by the heat capacity of the vaporized product supplied from the lower part and an auxiliary external heater.

Then, in the raw material supply section 2, the input polyolefin plastic waste is melted at the above-mentioned set temperature, and the molten raw material is fed into the pyrolysis reaction section 3 by the screw feeder 5, where a part of it is heated at the above-mentioned set temperature. undergoes thermal decomposition. The vaporous product generated by thermal decomposition is re-decomposed and reduced in molecular weight as described above while passing through the catalyst layer reaction section 4. On the other hand, a cooling pipe 10 having an external condenser 9 is connected to the upper side of the catalyst layer reaction section 4, and an oil storage tank 11 is provided at the tip of the cooling pipe 10.

Therefore, the product re-decomposed in the catalyst layer reaction section 4 and reduced in molecular weight is cooled in the process of passing through the cooling pipe 10.
It is liquefied and collected in the oil storage tank 11. Since a condenser 12 is placed above the oil storage tank 11, the produced oil in the oil storage tank 11 is cooled again and most of it is collected in the oil tank 11. The collected oil is transferred to valve 13.
It can be taken out by opening it. Note that the temperature control of the catalyst layer reaction section 4 is performed by observing the thermometer 6, and the temperature control of the thermal decomposition reaction section 3 and the level control of the liquid phase are performed by observing the thermometer 8 and the level meter 7.

Next, experimental results of pyrolysis treatment of polyolefin plastic waste using the pyrolysis reaction apparatus according to the present invention will be shown.

[1' Thermal decomposition reactor This is an iron controlled thermal decomposition reactor having the same structure as the illustrated embodiment, the thermal decomposition reaction part has a height of 20 m, the inner diameter side is 140 m, the catalyst layer reaction part has a height of 12 m, Inner diameter 65.

■ Raw materials used Polyethylene container waste, agricultural waste polyethylene film 70 yen.

The raw materials used above are put into the raw material supply section 2 and heated to 360 °C.
The mixture was heated to melt and connected to the thermal decomposition reaction section 3 by the screw feeder 5, and then supplied to the catalyst layer reaction section 4, where it was subjected to thermal decomposition treatment at the temperatures shown in the table below.

The analysis results of the obtained hydrocarbon oil are shown below.

[Brief explanation of the drawing]

The drawing is a schematic diagram of a thermal decomposition reactor showing an embodiment of the present invention. In the figure, 1 is a thermal decomposition reaction device, 2 is a raw material supply section, 3 is a thermal decomposition reaction section, and 4 is a catalyst layer reaction section.

Claims (1)

[Claims] 1. Particles obtained by heat-melting polyolefin plastic waste, then heating it in a range of 440 to 500°C to thermally decompose it, and heating the vaporized product generated by the thermal decomposition to 350 to 470°C. A method for pyrolyzing polyolefin plastic waste, which is characterized by subjecting polyolefin plastic waste to secondary pyrolysis treatment by passing it through a catalyst layer having a diameter of 1 to 15 mm. 2. Polyolefin plastic waste consisting of a raw material supply section that thermally melts polyolefin plastic waste, a thermal decomposition reaction section for molten plastic waste, and a catalytic reaction section consisting of a catalyst layer with a particle size of 1 to 15 mm. Equipment for thermal decomposition of materials.