Patent ID: 7316127
Filing Date: 2008-01-08
Classification: C07C,F25J

Abstract:
1. A process for separating an inlet gas stream containing methane and lighter components, C2 components, C3 components and heavier hydrocarbons into a more volatile gas fraction containing substantially all of the methane and lighter components and a less volatile hydrocarbon fraction containing a major portion of C2 components, C3 components and heavier hydrocarbons, the process comprising the steps of: splitting a feed gas stream into a first feed stream and a second feed stream; cooling and partially condensing the first feed stream and the second feed stream to produce a first cooled feed stream and a second cooled feed stream; supplying an absorber tower containing one or more mass transfer stages with the first cooled feed and second cooled feed streams; separating the first and second cooled feed streams in the absorber tower to produce a first vapor stream and a first liquid stream; expanding the first vapor stream to a low pressure so that the first vapor stream forms a lower fractionation tower feed stream; supplying a fractionation tower with the lower fractionation tower feed stream, a first fractionation tower reflux stream, and a second fractionation tower reflux stream; supplying at least a portion of the first liquid stream as a top stripping feed stream to an at least partially reboiled stripping tower that contains one or more mass transfer stages, the at least partially reboiled stripping tower thereby separating the at least a portion of the first liquid stream to produce a stripper overhead stream and a stripper bottoms stream; cooling and thereby substantially condensing the stripper overhead stream to produce the second fractionation tower reflux stream that is sent to the fractionation tower; supplying the fractionation tower with at least a portion of the stripper bottoms stream; separating the at least a portion of the stripper bottoms stream, along with the lower fractionation tower feed stream, the first fractionation tower reflux stream, and the second fractionation tower reflux stream in the fractionation tower to produce a tower bottoms stream and a tower overhead stream; warming the tower overhead stream to produce a residue gas stream; splitting the residue gas stream into a residue recycle stream and a volatile residue gas stream after the step of warming the tower overhead stream to produce the residue gas stream; cooling and thereby substantially condensing the residue recycle stream prior to returning the residue recycle stream to the fractionation tower as the first fractionation tower reflux stream; and controlling quantities and temperatures of the first and second fractionation tower reflux streams, lower fractionation tower feed stream, and stripper bottoms stream such that a major portion of the C2 components, C3 components and heavier hydrocarbons is recovered in the tower bottoms stream.