3.1. OSMAHRDIn OSMAHRD, one-stage membrane separation unit is addedin the upstream of the original amine absorption process (Fig. 2).Design variables need to be optimized to minimize EAOC (Eq. (1)).In this case, the only decision variable is membrane area. Design and operating conditions in the original process act as constraintsbecause they should not experience major variation in the retrofitdesign; i.e., the absorber inlet stream pressure and temperatureremain the same, and its mole fraction of acid components shouldnot exceed 10% of the original value (due to corrosion problem).Objective function for optimization is: