Dehydrogenation and pyrolysis product recovery with a common C3 splitter
A process and apparatus integrate recovery of propylene from a pyrolysis reactor and a paraffin dehydrogenation reactor. A common C3 splitter column fractionates propylene product from propane recycle to a paraffin dehydrogenation reactor. The C3 hydrocarbons may be provided from a pyrolysis reactor and from a dehydrogenation reactor.
1 . A process for separating propylene from propane comprising:
fractionating a C3 pyrolyzed stream and a dehydrogenation stream into a propylene product stream and a propane recycle stream;
dehydrogenating said propane recycle stream,
wherein an overhead stream from a fractionation column is separated into an overhead vapor stream and an overhead liquid stream; and
compressing the overhead vapor stream to provide a compressed vapor stream and reboiling a bottoms stream from said fractionation column by heat exchange with said compressed vapor stream.
2 . The process of claim 1 further comprising feeding the C3 pyrolyzed stream to a fractionation column above the dehydrogenation stream.
3 . The process of claim 1 further comprising stripping said dehydrogenation stream of light gases before fractionation with said C3 pyrolyzed stream.
4 . The process of claim 1 further comprising taking a propane stream from a bottom of a fractionation column and reboiling a first portion by heat exchange with steam and reboiling a second portion by heat exchange with water.
5 . The process of claim 4 further comprising condensing a propylene product stream by heat exchange with cooling water.
6 . The process of claim 1 further comprising fractionating said dehydrogenation stream in a prefractionation column to provide a prefractionation stream and said propane recycle stream and fractionating the prefractionation stream in a main column.
7 . The process of claim 6 further comprising fractionating the C3 pyrolyzed stream in a main column to provide a propylene product stream and a main bottom stream.
8 . The process of claim 6 further comprising fractionating the main bottom stream in the prefractionation column.
9 . The process of claim 6 further comprising fractionating the prefractionation stream in said main column to provide a propylene product stream and a main bottom stream.
10 . The process of claim 6 wherein said prefractionation column is operated at a higher overhead pressure than said main fractionation column.
11 . The process of claim 6 wherein an overhead stream from said main fractionation column is separated into a main vapor stream and a main overhead liquid stream;
compressing the main vapor stream to provide a compressed main vapor stream and reboiling said main fractionation bottoms stream from said main fractionation column by heat exchange with said compressed main vapor stream.
12 . The process of claim 6 further comprising fractionating the C3 pyrolyzed stream in said prefractionation column.
13 . The process of claim 12 further comprising recovering said main fractionation bottoms stream as said propane recycle stream.
14 . A process for separating propylene from propane comprising:
fractionating a dehydrogenation stream into a propylene stream and a propane recycle stream in a fractionation column;
fractionating a C3 pyrolyzed stream into a propylene stream and a propane recycle stream; and
dehydrogenating said propane recycle stream,
taking a propane stream from a bottom of a fractionation column and reboiling a first portion of the propane stream by heat exchange with a first stream and reboiling a second portion of the propane stream by heat exchange with a second stream.
15 . The process of claim 14 wherein said fractionation column is a prefractionation column and fractionating said propylene stream from an overhead of said prefractionation column in a main fractionation column to provide said propylene product stream.
16 . The process of claim 15 further comprising fractionating said C3 pyrolyzed stream in said prefractionation column.
17 . The process of claim 15 further comprising fractionating said C3 pyrolyzed stream in said main fractionation column.
18 . An apparatus for separating propylene from propane comprising:
a fractionation column in downstream communication with dehydrogenation reactor through a dehydration line and a pyrolysis reactor through a C3 pyrolyzed line;
said dehydrogenation reactor in downstream communication with said fractionation column,
wherein an inlet for said C3 pyrolyzed line to the fractionation column is at an elevation above an inlet for said dehydrogenation line to the fractionation column.
19 . The apparatus of claim 18 further comprising a prefractionation column in downstream communication with said dehydrogenation reactor and said fractionation column in downstream communication with said prefractionation column.