Processes and systems for formation of recycle-content hydrocarbon compositions
Processes and systems for making recycle content hydrocarbons, including olefins, are provided that integrate a cracker unit with one or more other processing units. For example, in some cases, a pyrolysis unit and cracking unit may share a common energy exchange zone so that energy from one unit may be transferred to the other. The energy exchange may be direct or indirect and may be present at one or more locations between the units.
1 . A process for making olefins, said process comprising:
(a) pyrolyzing at a temperature from about 775° C. to about 1,100° C. a feed stream comprising a recycled waste material in a pyrolysis unit to provide a stream comprising recycle content pyrolysis oil;
(b) cracking a cracker feed stream comprising
(i) at least 1 and not more than 40 weight percent of a recycle content pyrolysis oil composition (r-pyoil), along with
(ii) at least 60 weight percent of a non-recycle cracker feed chosen from propane, ethane, and/or natural gasoline, in a steam cracker furnace of a steal cracking unit to provide an olefin-containing effluent, wherein said r-pyoil has a C 8+ content of at least 35 weight percent, based on the total weight of said r-pyoil; and wherein said r-pyoil comprises not more than about 20 weight percent total aromatics, based on the total weight of said r-pyoil; and
(c) transferring energy between at least one pyrolysis unit process stream and at least one steam cracking unit process stream.
2 . The process of claim 1 , wherein the recycled waste material is present in the pyrolysis feed stream in an amount of at least 5 weight percent and/or not more than about 95 weight percent, based on the total weight of the feed stream.
3 . The process of claim 1 , wherein the recycled waste material is present in the pyrolysis feed stream in an amount of at least 5 weight percent and/or not more than about 99 weight percent, based on the total weight of the feed stream.
4 . The process of claim 1 , wherein said recycled waste material comprises recycled waste plastic.
5 . The process of claim 1 , wherein said recycled waste material comprises at least 5 weight percent of recycled waste plastic and/or not more than 99 weight percent of waste plastic based on the total weight of the feed stream.
6 . The process of claim 1 , wherein said recycled waste comprises waste plastics, waste textiles, waste carpet fibers, waste modified cellulose, waste biomass, post-industrial waste streams, intermediate industrial waste streams, or combinations thereof.
7 . The process of claim 1 , wherein said pyrolyzing provides a stream of pyrolysis gas comprising predominantly C4 and lighter components and wherein said transferring includes combusting at least a portion of said pyrolysis gas as fuel in said furnace of the cracking unit.
8 . The process of claim 1 , further comprising separating at least a portion of the olefin-containing effluent in at least one distillation column to provide an overhead gas stream and a liquid bottoms stream.
9 . The process of claim 1 , wherein said pyrolysis unit further comprises a pyrolysis furnace for carrying out at least a portion of said pyrolyzing, and wherein said transferring comprises combusting at least a portion of said overhead gas stream from said distillation column in said cracking unit as fuel in said pyrolysis furnace.
10 . The process of claim 1 , further comprising heating at least a portion of said liquid bottoms stream from said distillation column via indirect heat exchange with a warmed stream from said pyrolysis unit.
11 . The process of claim 1 , further comprising contacting at least a portion of said olefin-containing effluent with a quench liquid to provide a warmed quench liquid, and wherein said transferring comprises preheating the feed stream to the pyrolysis unit via indirect heat exchange with the warmed quench liquid.
12 . The process of claim 1 , wherein said transferring comprises heating a stream of boiler feed water via indirect heat exchange with at least a portion of said pyrolysis effluent stream.
13 . The process of claim 1 , wherein said transferring comprises preheating the cracker feed stream via indirect heat exchange with at least a portion of said pyrolysis effluent stream.
14 . The process of claim 1 , wherein said transferring includes preheating the feed to said pyrolysis unit in a convection section of said cracker furnace.
15 . The process of claim 1 , wherein said transferring includes transferring energy between at least one pyrolysis unit process stream and at least one cracking unit process stream via at least one intermediate heat transfer stream.
16 . The process of claim 1 , wherein said intermediate heat transfer stream comprises a stream of boiler feed water and wherein said transferring includes heating said boiler feed water to form steam with one of the cracking unit stream and the pyrolysis unit stream and using said steam to heat the other of said cracking unit stream and the pyrolysis unit stream.
17 . The process of claim 1 , wherein said transferring includes heating said boiler feed water in a convection section of said cracker furnace to form steam, and using said steam to heat said pyrolysis unit process stream.
18 . The process of claim 1 , wherein said transferring includes heating said boiler feed water via indirect heat exchange with the effluent from said pyrolysis unit, and using said steam to heat said cracking unit process stream.