Chemical recycling of plastic-derived streams to a cracker separation zone
Methods and systems are provided for the conversion of waste plastics into various useful downstream recycle-content products. More particularly, the present system and method involves integrating a pyrolysis facility with a cracker facility by introducing at least a stream of r-pyrolysis gas into the cracker facility. In the cracker facility, the r-pyrolysis gas may be separated to form one or more recycle content products, and can enhance the operation of the facility.
1. A method for making an olefin product, said method comprising: separating a feed stream comprising a recycle content pyrolysis gas (r-pyrolysis gas) in at least one fractionator downstream of a cracker furnace, wherein said r-pyrolysis gas has not been produced in said cracker furnace; wherein said r-pyrolysis gas is produced from mixed plastic waste; and wherein said cracking furnace produces said olefin product, and wherein said r-pyrolysis gas comprises: at least 20 and/or not more than 75 weight percent of ethylene and/or propylene, at least 5 and/or not more than 50 weight percent of ethane and/or propane, at least 5 and/or not more than 60 weight percent of methane, an ethylene to ethane weight ratio or propylene to propane weight ratio of at least 1:1 and/or not more than 3:1, and at least one of the following properties (i) through (ix):
(i) C4 hydrocarbons in an amount of not more than 20 weight percent; (ii) hydrogen in an amount of not more than 10 weight percent; (iii) C3+ diolefins in an amount of not more than 10 weight percent; (iv) C4+ olefins in an amount of not more than 10 weight percent; (v) C4 paraffins in an amount of not more than 5 weight percent; (vi) halogens in an amount of not more than 1 ppm; (v) carbonyls in an amount of not more than 100 ppm; (vi) carbon dioxide in an amount of not more than 100 ppm; (vii) carbon monoxide in an amount of not more than 2500 ppm; (viii) arsine and/or phosphine in an amount of not more than 15 ppb; and (ix) sulfur-containing compounds in an amount of not more than 100 ppm, wherein each of the above quantities are in amounts by weight, based on the total weight of the composition.
2. The method of claim 1 , wherein said feed stream comprises at least a portion of an olefin containing effluent stream withdrawn from said cracker furnace.
3. The method of claim 1 , further comprising compressing a pyrolysis stream comprising said r-pyrolysis gas and introducing the compressed stream into said fractionator downstream of said furnace.
4. The method of claim 3 , further comprising prior to compressing, combining said pyrolysis gas stream with an olefin-containing effluent stream from said cracker furnace, and compressing the combined stream.
5. The method of claim 1 , further comprising, cooling an r-pyrolysis gas stream to form a cooled r-pyrolysis gas stream, wherein said feed stream comprises at least a portion of said cooled r-pyrolysis gas stream.
6. The method of claim 5 , further comprising prior to cooling, combining said r-pyrolysis gas stream with an olefin-containing effluent stream from said cracker furnace, and cooling the combined stream.
7. The method of claim 1 , wherein said fractionator is selected from the group consisting of a demethanizer, a deethanizer, and a depropanizer.
8. The method of claim 1 , wherein said fractionator is selected from the group consisting of an ethane-ethylene splitter and a propane-propylene splitter.
9. The method of claim 1 , wherein said feed stream comprises at least 5 and not more than 60 weight percent olefins, based on the total weight of said feed stream.