Amine absorption process is modeled and simulated in AspenPlus 7.2 with amine package as the fluid package. Absorber andregenerator are the two major unit operations in this process. Sievetrays are assumed for the absorber. For the base case, 20 stages areassumed in the absorber (Sohbi et al., 2007). Another importantparameter is amine circulation rate, whose initial guess is estimatedfollowing the equations of Arnold and Stewart (1999). This way ofcalculating the initial guess enables faster convergence of AspenPlus simulation. DEA temperature at absorber inlet is set at 5–7◦Chigher than inlet gas to guarantee occurrence of absorption. Pres-sure drop of 35 kPa is assumed in the column (i.e. 5481 kPa in thetop and 5516 kPa in the bottom).