Processes and systems for making recycle content hydrocarbons
Processes and systems for making recycle content hydrocarbons, including olefins, from recycled waste material. Recycle waste material may be pyrolyzed to form recycle content pyrolysis oil composition (r-pyoil), at least a portion of which may then be cracked to form a recycle content olefin composition (r-olefin). In some cases, the pyrolysis and cracking may be carried out in different sections of the same furnace, or in different furnaces in the same cracker facility. Pyrolysis conducted in a furnace may or may not require retrofitting a furnace previously used to crack alkanes to form olefins.
1. A process for making olefins, said process comprising:
(a) pyrolyzing a feed stream comprising recycle waste material in a first section of a cracking furnace to provide a stream comprising a recycle content pyrolysis composition (r-pyrolysis stream); and
(b) cracking at least a portion of said r-pyrolysis stream in a second section of said cracking furnace to form an olefin-containing effluent; wherein said 1 st and 2 nd sections are in a single cracking furnace; and wherein said first section is at least partially heated by said second section; where said olefin-containing effluent predominantly comprises propylene; and wherein said cracking furnace has been retrofitted from a furnace previously used to crack alkanes to form olefins; wherein said pyrolyzing and cracking are done in said single cracking furnace; wherein said r-pyrolysis stream has a C 8 + content of at least 15 weight percent, based on the total weight of said r-pyrolysis stream; and wherein said r-pyrolysis stream comprises not more than about 25 weight percent total aromatics, based on the total weight of said r-pyrolysis stream.
2. A process for making olefins, said process comprising:
(a) pyrolyzing a stream comprising recycle waste material in a first section of a cracking furnace;
(b) separating the pyrolyzed stream into a light fraction and a heavy fraction; and
(c) cracking at least a portion of said light fraction in a second section of said cracking furnace; wherein said 1 st and 2 nd sections are in a single cracking furnace; and wherein said first section is at least partially heated by said second section; wherein said olefin-containing effluent predominately comprises propylene; and wherein said cracking furnace has been retrofitted from a furnace previously used to crack alkanes to form olefins; wherein said pyrolyzing and cracking are done in said single cracking furnace; wherein said r-pyrolysis stream has a C 8 + content of at least 35 weight percent, based on the total weight of said r-pyrolysis stream; and wherein said r-pyrolysis stream comprises not more than about 25 weight percent total aromatics, based on the total weight of said r-pyrolysis stream.
3. The process of claim 1 , further comprising adding a carrier fluid stream to the r-pyrolysis stream prior to at least a portion of said cracking.
4. The process of claim 2 , further comprising adding a carrier fluid stream to the pyrolyzed stream prior to at least a portion of said cracking.
5. The process of claim 2 , wherein said carrier fluid stream comprises a predominantly C2 to C4 hydrocarbon stream.
6. The process of claim 3 , wherein said carrier fluid stream comprises a predominantly C2 to C4 hydrocarbon stream.
7. The process of claim 3 wherein said carrier fluid stream comprises a predominantly C5 to C22 hydrocarbon stream.
8. The process of claim 2 , wherein said first section is a convection section and said second section is a radiant section.
9. The process of claim 3 , wherein said furnace includes a single fire box and each of said first and second coils are disposed in said fire box.
10. The process of claim 1 , wherein said pyrolyzing is carried out for a pyrolysis residence time of at least 30 seconds and/or not more than 10 minutes.
11. The process of claim 1 , wherein at least one of the first and second sections comprises a single pass coil.
12. The process of claim 1 , wherein at least one of the first and second sections comprises a multiple pass coil.
13. The process of claim 1 , wherein at least one of the first and second sections comprises a coil comprising two or more tubes.