Process for using alkyl substituted c8-c10 aromatic hydrocarbons as

Abstract

A process is disclosed in which a preferential physical solvent selectively extracts and strips desirable C.sub.2 + hydrocarbons from a raw hydrocarbon gas stream which is fed into the midsection of an Extractor-Stripper (ES) column, the rich solvent produced from the bottoms thereof being regenerated in a distillation column which produces a hydrocarbon gas liquid stream as product and a lean physical solvent for recycling to the top of the ES column. When certain operating conditions and product specifications necessitate operating the ES column bottoms at a temperature high enough to become relatively energy inefficient, a single-stage intermediate flashing vessel is provided for effectively removing undesirable hydrocarbons at a pressure consistent with the operating pressure of the distillation column. The separated overhead vapor stream from the flashing vessel contains all of the undesirable components along with some desirable hydrocarbons. This stream is compressed to a pressure level consistent with the operating pressure of the ES column, and the compressed vapors are recycled to the ES column for additional recovery of desirable hydrocarbons. Suitable preferential physical solvents are C.sub.8 -C.sub.10 aromatic compounds having methyl, ethyl, or propyl aliphatic groups, including mesitylene, n-propyl benzene, n-butyl benzene, o-xylene, m-xylene, p-xylene, and mixtures thereof, and certain reformate streams rich in mixed xylenes and other C.sub.8 -C.sub.10 aromatics.