Decomposition of waste plastics

Abstract

Far infrared ray heating technology is used to breakdown waste plastic and resultant heavy oils into usable products. Waste plastics may thus be processed into petroleum products and used to generate energy.

Description

SUMMARY OF THE INVENTION[0001]Conventional reactors for converting waste plastics into oil, for example, as disclosed in U.S. Pat. Nos. 5,947,721, 5,951,826 and 5,584,969, all use high temperature flue gas to supply the heat required to decompose the plastics into oil. The reactors and processes therein involve some disadvantages. First the heating efficiency of the reactors is not high. The high temperature flue gas transfers the heat to the outer surface of the reactor, and then the outer surface conducts the heat to the plastics in the reactor. Because the heat is not directly transferred to the plastics, the heating efficiency is low. Nevertheless, despite the low heat-conducting efficiency there are serious problems from coking on the inner wall of the reactor. The decomposition of oil usually applies pyrrolysis conditions cure heavy oil to light oil, increasing the efficiency of the light oil. Thus, pyrrolysis is one desirable waste plastic and waste oil reclamation method, as...

AI Technical Summary

Benefits of technology

[0004]Various metal oxides, nitrides, carbides and borides are far infrared radiators, and emit far infrared radiation of different wavelengths when heated, and the wavelength is different at different temperatures. It is thus possible to get high heating efficiency by selecting the wavelength of the far infrared radiation within desired ranges by selecting the appropriate far infrared ray radiator and working temperature. The “FIR” heater can composite electrical resistance space, far infrared radiator, insulator, and protective shell. The protective shell contains an isolation device that is made of metal, for example, iron or stainless. The isolation device, which separates the heater from the stream in the reactor, is preferably resistant to high temperature, high pressure and corrosion. In order to enhance the emitting of the far infrared radiation, a layer of the far infrared radiator may cover the outer surface of the far infrared ray heater. The far infrared ray radiator can be made into various shapes, for example, rod-shape, band-shape and other shapes, and on the outside can be encased by metal pipe, and finally painted with the far infrared radiator, whereby far infrared radiation can directly heat the plastics. The protective shell is preferably in the form of a rod over the heating element and heat-absorbing material, although any shape is permissible. Preferably, the rod is bullet-shaped. When decomposed, the plastics will generate coke. This coke will cover the outer surface of the radiator, thus decreasing the heating efficiency. Consequently, an agitator is installed in the reactor. The flowing liquid causes the coke to peel off the rods, and the heating efficiency is not affected or minimally affected. The agitator may be a gate, propeller, combinatorial agitator or other shapes of agitator. The sludge in the reactor may be discharged into a screw drier in which the heavy oil components in the sludge are re-cracked under high temperature and the gas products go back to the reactor. At the end of the drier, the dried sludge is cooled and crushed into pieces which can be collected as carbon residual.

Problems solved by technology

First the heating efficiency of the reactors is not high.

Because the heat is not directly transferred to the plastics, the heating efficiency is low.

Nevertheless, despite the low heat-conducting efficiency there are serious problems from coking on the inner wall of the reactor.

Because the heat-conducting coefficient of typical waste plastic is low, it is difficult to conduct the heat into it from the heat source.

When decomposed, the plastics will generate coke.

This coke will cover the outer surface of the radiator, thus decreasing the heating efficiency.

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