Optimal design of spiral-wound membrane networks for gas separations

An optimal design strategy for spiral-wound membrane networks based on an approximate permeator model and a mixedinteger nonlinear programming (MINLP) solution strategy is proposed. A general permeator system superstructure is used to embed a very large number of possible network con®gurations. The superstructure allows the development of a MINLP design strategy which simultaneously optimizes the permeator con®guration and operating conditions to minimize an objective function which approximates the total annual process cost. Case studies for the separation of CO2/CH4 mixtures in natural gas treatment and enhanced oil recovery are presented. Permeator con®gurations are derived for different number of separation stages for both continuous and discrete membrane areas. The proposed approach provides an ef®cient methodology for the preliminary design of multi-stage membrane separation systems for binary gas mixtures. # 1998 Elsevier Science B.V. All rights reserved.