Patent ID: 6712880
Filing Date: 2004-03-30
Classification: F25J

Abstract:
A process for separating a heavy key component from an inlet gas stream containing a mixture of methane, C2 compounds, C3 compounds, and heavier compounds, comprising the following steps:(a) at least partially condensing and separating the inlet gas to produce a first liquid stream and a first vapor stream; (b) expanding at least a portion of the first liquid stream to produce a first fractionation feed stream; (c) supplying a fractionation column the first fractionation feed stream and a second fractionation feed stream, the fractionation column produces a fractionation overhead vapor stream and a fractionation bottom stream; (d) expanding at least a portion of the first vapor stream to produce an expanded vapor stream; (e) supplying an absorber the expanded vapor stream and an absorber feed stream, the absorber produces an absorber overhead stream and an absorber bottom stream, the absorber having an absorber pressure that is substantially greater than and at a predetermined differential pressure from a fractionation column pressure; (f) compressing at least a portion of the fractionation overhead vapor stream or a second vapor stream essentially to the absorber pressure to produce a compressed second vapor stream and to control the fractionation column pressure by maintaining the predetermined differential pressure from the absorber pressure; (g) at least partially condensing the compressed second vapor stream to produce the absorber feed stream; and whereby the fractionation bottom stream contains a majority of the heavy key component and heavier compounds.