Reactor Types Used for Pyrolysis

Different types of reactors are utilized for a wide variety of pyrolysis applications, including processing of waste plastics. The worldwide waste plastic pyrolysis systems utilize the fixed-bed designs of vertical shaft reactors and dual fluidized-bed, rotary kiln and multiple hearth reactor systems. The type of reactor used is chiefly based on material to be pyrolyzed and expected products from the pyrolysis. Stainless steel shaking type batch autoclave and stainless steel micro tubular reactors have also been used extensively [14]. Fluidized-bed reactors have been extensively used in producing raw petrochemicals from the pyrolysis of waste plastics [22, 24]. 

The semi-continuous type of reactor with the large capacity was comprised of a pyrolysis chamber, a catalytic cracking chamber and a separation and purifying section. The feed plastic material was melted and decomposed in the pyrolysis chamber held at the ambient pressure and at the temperature 723-783 K, and fed to the catalytic cracking chamber. A reflux condenser was used to separate and purify the products formed in the chamber and individual factors were obtained using fractional distillation apparatus [26]. Different types of reactors are being utilized depending on the type of feed and the expected products from the pyrolysis. 

The pyrolysis liquids consist mainly of tar, light oil, and liquor. The tar contains 16-25% olefins, 62-80% aromatics, and 3-14.5% paraffins and naphthenes, and the remainder is organic compounds that have been identified as acids, bases, ketones, and 

The production of plastics also involves the use of potentially harmful chemicals under the name of stabilizers or colorants. Many of these stabilizers/additives have not undergone environmental risk assessment and their impact on human health and the environment is currently uncertain and doubtful. Phthalates, as additives, are widely used in the manufacturing of PVC products, and risk assessments of the effects of phthalates on the environment are currently being carried out. Recent research for the Community Recycling Network casts doubt on whether pyrolysis and gasification are the right processes for dealing with the residual municipal waste. 

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