Ethane recovery in a conventional turboexpander process is optimized considering different demethanizer pressures and different feeds: a lean gas and a rich one. The design variables are varied, while meeting process constraints, in order to find the optimum conditions achieving the maximum profit. The analysis covers the whole process including the refrigeration part, and the entire typical demethanizer pressure range. The optimum ethane recovery is compared with the maximum possible recovery for each value of the demethanizer pressure. Recommendations are given regarding the selection of the level of ethane recovery, along with the demethanizer pressure, and refrigeration recovery system. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.