Circular economy for plastic waste to polyethylene via refinery crude unit
AssigneeChevron U.S.A. Inc.
InventorHye-Kyung Timken
Life of this patent
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Abstract
Provided is a continuous process for converting waste plastic into a feedstock for polyethylene polymerization. The process comprises selecting waste plastics containing polyethylene and/or polypropylene, and then passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is then separated into offgas, a pyrolysis oil comprising a naphtha/diesel/heavy fraction, and char. The pyrolysis oil is passed to a crude unit in a refinery from which a naphtha fraction (C5-C8), or a propane and butane (C3-C4) fraction, is recovered. The naphtha fraction, or propane and butane (C3-C4) fraction, is then passed to a steam cracker for ethylene production.
Claims18
A continuous process for converting waste plastic into naphtha for polyethylene polymerization comprising:
- (a) selecting waste plastics containing polyethylene and/or polypropylene with the waste plastics containing less than 5 wt % of polyethylene terephthalate and polyvinyl chloride;
- (b) passing the waste plastics from (a) through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent;
- (c) separating the pyrolyzed effluent into offgas, a pyrolysis oil and optionally pyrolysis wax comprising a naphtha/diesel fraction and a heavy fraction, and char;
- (d) passing the pyrolysis oil and wax to a crude unit in a refinery with the volume flow of pyrolysis oil and wax to the crude unit comprising up to but no more than about 50 volume % of the total hydrocarbon flow to the crude unit;
- (e) recovering a naphtha fraction (C5-C8) from the crude unit;
- passing the naphtha fraction to a steam cracker for ethylene production.
A continuous process for converting waste plastic into a C3-C4 stream for polyethylene polymerization comprising:
- (a) selecting waste plastics containing polyethylene and/or polypropylene with the waste plastics containing less than 5 wt % of polyethylene terephthalate and polyvinyl chloride;
- (b) passing the waste plastics from (a) through a pyrolysis reactor to thermally crack at least potion of the polyolefin waste and produce and pyrolyzed effluent;
- (c) separating the pyrolyzed effluent into offgas, a pyrolyzed oil and optionally wax comprising a naphtha/diesel fraction and heavy fraction, and char;
- (d) passing the pyrolysis oil to a crude unit in a refinery with the volume flow of pyrolysis oil and wax to the crude unit comprising up to but no more than about 50 volume % of the total hydrocarbon flow to the crude unit;
- (e) recovering a portion of propane and butane (C3-C4) fraction from the crude unit;
- and
- passing the C3-C4 fraction to a steam cracker for ethylene production.
A process for converting waste plastic into chemicals useful in preparing polyethylene, comprising:
- (a) selecting waste plastics containing polyethylene and/or polypropylene with the waste plastics containing less than 5 wt % of polyethylene terephthalate and polyvinyl chloride;
- (b) pyrolyzing the waste plastic and recovering a pyrolysis oil and wax comprising a naphtha/diesel/heavy fraction;
- and
- (c) passing the pyrolysis oil to a crude unit in a refinery with the volume flow of pyrolysis oil and wax to the crude unit comprising up to but no more than about 50 volume % of the total hydrocarbon flow to the crude unit.
Dependencies are inferred from the claim text.