Abstract: An improved system for separating higher boiling hydrocarbon products from methane in a gas/liquid extraction plant. The improvements lies in combining the fractionating tower with a counterflow plate and tube heat exchanger through which the refrigerated low pressure gas flows from top end to bottom end, and the precooled high pressure gas flows upwardly in counterflow relation. The heat exchanger is in the form of an annular chamber with tubes running the full length from bottom to top and plates forcing a zig-zag flow of the cold gas. This sets up a more or less linear temperature gradient which is impressed on the fractionating tower inside of the heat exchanger, which forms the inner wall of the heat exchanger and makes for more efficient and effective fractionation of the entering gas and vapor mixture.