Method and apparatus for reclaiming oil from waste plastic

Abstract

This invention provides a method for reclaiming oil from waste plastic in such a way that thermosetting resins and solid foreign matter in the plastic will not pose a problem. This method greatly reduces the burden of presorting the garbage or industrial waste. To achieve this objective when oil is to be reclaimed from a waste plastic containing chlorine compounds, such as vinyl chloride, the plastic must first be stripped of chlorine. Prior to pyrolysis, while being conveyed forward in a continuous stream, the plastic is mixed with heated sand and/or an additive agent to raise its temperature to 250-350° C. This creates a product which is comprised of a mixture of sand and substantially dechlorinated plastic. The product is mixed with heated sand to heat it directly to a temperature of 350-500° C. It is maintained at this temperature until pyrolysis occurs. In order to obtain high-quality oil with a low boiling point, a first gas/liquid separation process separates the product obtained from the aforesaid pyrolysis into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gases, and recirculates the liquid high-boiling point oil to the pyrolysis process, and a second gas/liquid separation process separates the gaseous low-boiling point oil and low molecular-weight gases into liquid low-boiling point oil and low molecular-weight gases. The first and second gas/liquid separation process are connected in sequence.