ENHANCED OLEFIN RECOVERY PROCESS
A demethanizer employing C3, C4 and C4+ hydrocarbons as absorbents can be employed in a methanol to olefin process to reduce both operating and capital costs in comparison to a convention process which employs only cryogenic distillation to remove methane and other low boilers from a light olefin process stream. By reducing the use of propane, the size and operating costs of the C3 splitter can be reduced thereby providing an economic advantage over conventional applications.
1 . A system for separating light olefins from an MTO process stream, comprising:
a demethanizer configured to remove methane from a light olefin containing process stream wherein the demethanizer uses an absorbent selected from the group consisting of C3-C5 hydrocarbons, and combinations thereof, wherein if the absorbent consists of C3 hydrocarbons then the adsorbent is not exclusively propane.
2 . The system of claim 1 , further comprising:
a deethanizer receiving an effluent of the demethanizer.
3 . The system of claim 2 , further comprising:
a first line returning a first portion of an effluent from the deethanizer to the demethanizer;
an acetylene reactor receiving a second portion of the effluent from the deethanizer; and
a depropanizer receiving a third portion effluent from the deethanizer.
4 . The system of claim 3 , further comprising a:
C2 splitter receiving an effluent from the acetylene reactor;
a second line sending a portion of the effluent from the C2 splitter to the demethanizer;
a debutanizer receiving a portion of the effluent from the depropanizer; and
a third line sending a portion an effluent from the debutanizer to the demethanizer.
5 . The system of claim 1 , wherein propane makes up less than ten percent of the total amount of the selected absorbent.
6 . The system of claim 1 , wherein propane makes up less than one percent of the total amount of the selected absorbent.