Two membranes optimization model to methane stream purification

Abstract

In this work, a two-stage membrane process for CH₄/CO₂ separation was modeled. For this the program GAMS (General Algebraic Modeling System) was used, optimizing the total annual cost of the process. The influence of feed composition, feed pressure and total recovery of CH₄ over the total cost, the energy consumption and the required membrane area for the separation was analyzed. An increase of recovery from 90% to 95% causes an increase of 5% of energy consumption. By decreasing the feed pressure from 1,8 to 1,5 MPa the energy consumption is decreased by 8,25%, although the required membrane area increases by 21,6%.
Finally, if the feed composition of CH₄ is changed from 90% to 75% the energy consumption decreases in 16,67%, however the specific cost increases in 18,12%.