System and process for the recovery of propylene and ethylene from refinery offgases
AssigneeChart Industries, Inc.
InventorRichard B. Hopewell
Life of this patent
Estimating the term…
Abstract
A system and process for the recovery of ethylene and propylene from a gas stream, such as a refinery offgas stream. The process comprises withdrawing, cooling, and recovering an overhead vapor stream from a single distillation column. The process includes withdrawing a liquid C3+, C4+, C5+ or C6+ bottoms product stream and recycling a portion of the bottoms steam to maintain an overhead column condenser at temperature refrigeration levels of above −140° F. and withdrawing a vapor side stream rich in propylene or ethylene-propylene.
Claims24
A process for the recovery of an olefin from a gas feed stream comprising hydrocarbons and minor amounts of olefins, which process comprises:
- a) introducing the gas feed stream into a single recovery distillation column having an upper tray section and with an overhead condenser and reflux drum;
- b) withdrawing an overhead vapor stream from said column;
- c) cooling and partially condensing the overhead vapor stream in the overhead condenser, to provide an overhead vapor-liquid;
- d) phase-separating the overhead vapor-liquid in the reflux drum;
- e) withdrawing from the reflux drum, an olefin-lean, overhead vapor stream and recycling the separated liquid from the reflux drum to the column;
- f) withdrawing from said column, a liquid C3+, C4+, C5+, or C6+ bottoms product stream;
- g) recycling at least a portion of the liquid bottoms product stream to the overhead condenser or the upper tray section of said column, to maintain the temperature of the overhead condenser above about −140° F. refrigeration temperature;
- and
- h) withdrawing an olefin-rich, vapor phase, side product stream rich in a selected olefin.
A process for the recovery of an ethylene-propylene mixture or propylene from a refinery offgas feed stream, which process comprises:
- a) introducing a waterwashed, dehydrated, refinery offgas feed stream, with acid gases removed, into a single recovery distillation column with an overhead condenser, reflux drum, and distillation trays, the offgas feed stream comprising C1+ hydrocarbons, ethylene, and propylene;
- b) withdrawing an overhead vapor stream from the recovery column;
- c) cooling and partially condensing the overhead vapor stream in the overhead reflux condenser, to provide a vapor-liquid overhead stream;
- d) phase-separating the vapor-liquid overhead stream in the reflux drum;
- e) withdrawing from the reflux drum, a lean, stripped, overhead vapor stream essentially free of ethane, propane, ethylene and propylene;
- f) withdrawing from, reboiling, and recycling to the column below the feed stream introduction, a side reboiler stream to enhance the concentration of the propylene and ethylene;
- g) withdrawing a heavy liquid C3+ to C6+ product stream from the bottom of the recovery column and recycling at least a portion of the liquid product stream to the overhead condenser or upper tray section of the recovery distillation column, to maintain the temperature of the overhead condenser at a level of about 0° F. to −115° F.;
- h) withdrawing a vapor side stream from the recovery column from trays between the side reboiler, the side stream comprising ethylene and propylene or propylene;
- i) condensing the vapor side stream;
- and
- j) recovering the ethylene-propylene mixture or propylene as a condensed recovery product stream.
Dependencies are inferred from the claim text.