Patent ID: 6534689
Filing Date: 2003-03-18
Classification: C10B,C10G,Y02P

Abstract:
A process for pyrolysis of waste plastics with hot circulating inert particulate solids to produce hydrocarbon oils, comprising the steps:(i) supplying said hot particulates to a feeder and fluidizing said particulates with an oxygen-free gas; (ii) delivering said hot particulates to the top of a downflow tubular reactor; (iii) introducing shredded waste plastics to the top of said downflow tubular reactor; (iv) melting and pyrolizing said shredded plastics in said tubular reactor at a temperature between 300Â° C. and 600Â° C. and a residence time of 0.5 to 3 seconds to form hydrocarbon oils and gaseous pyrolysis products; (v) separating the resulting gaseous pyrolysis products, said oxygen-free gas and said particulates in a reactor freeboard with a fluidized bed of said separated particulates, said bed being fluidized using an oxygen-free gas or circulating hydrocarbon gas, and thereafter in a cyclone separator; (vi) pyrolizing unconverted waste plastics in the fluidized bed of said reactor freeboard at a temperature between 300Â° C. and 600Â° C. and a residence time of 1 to 10 seconds to form hydrocarbon oils; (vii) separating said resulting gaseous pyrolysis products formed in said fluidized bed, said oxygen-free gas and said particulates in a reactor freeboard, and thereafter in a cyclone separator; (viii) quenching said separated gaseous pyrolysis products by preliminarily cooling said liquid pyrolysis products, and delivering a formed mixture into a fractionating column for subsequent cooling and fractionation of gaseous and liquid fractions; (ix) stripping said particulates from said hydrocarbons using an oxygen-free gas or circulating hydrocarbon gas in a fluidized bed; (x) delivering stripped hydrocarbons to the freeboard of said fluidized bed reactor; (xi) burning coke formed on said particulates during pyrolysis, in a fluidized bed combustor, wherein said particulates are fluidized using air at a temperature between 600Â° C. and 900Â° C., and (xii) separating said particulates from flue gas and supplying said particulates to said feeder.