A process for liquefying
natural gas in conjunction with producing a liquid
stream containing predominantly hydrocarbons heavier than
methane is disclosed. In the process, the
natural gas stream to be liquefied is partially cooled and divided into first and second streams. The first
stream is further cooled to condense substantially all of it, expanded to an
intermediate pressure, and then supplied to a
distillation column at a first mid-column feed position. The second stream is also expanded to
intermediate pressure and is then supplied to the column at a second lower mid-column feed position. A
distillation stream is withdrawn from the column below the
feed point of the second stream and is cooled to condense at least a part of it, forming a
reflux stream. At least a portion of the
reflux stream is directed to the
distillation column as its top feed. The bottom product from this distillation column preferentially contains the majority of any hydrocarbons heavier than
methane that would otherwise reduce the purity of the
liquefied natural gas. The residual gas stream from the distillation column is compressed to a higher
intermediate pressure, cooled under pressure to condense it, and then expanded to low pressure to form the
liquefied natural gas stream.