The LP deethanizer bottoms stream consists of C3+ components with a relatively high concentration of unsaturates. Depending on the specification requirements for the C3 and C4+ coproducts, this stream will be depropanized/hydrogenated/fractionated accordingly. Assuming that a desired coproduct is polymer-grade propylene, the C3 fraction will be hydrogenated to convert the bulk of the methyl acetylene/propadiene to propylene and then superfractionated to meet coproduct specifications (99.6 percent C3H6). Propane bottom product then will be recycled and recombined with fresh propane feed.