Lower and upper bounds of SA and SB are the same as those in OSMAHRD. Lower bound of P1stPermis specified to avoid vacuum operation, which is costly. Upper bound of P1stPermis specified such that partial pressure difference of CO2(mole fraction of H2S is low compared to CO2, and so the benchmark here is CO2) between membrane inlet and permeate streams could provide enough driving force; this specification can be explained by Fick’s law. To get the value of this upper bound, set both membrane areas at25,000 m2, and then adjust P1stPermuntil mole fraction of acid components in the first stage retentate stream (going to the absorber)approaches their respective upper bounds; this gives the upper bound of P1stPermto be ∼4500 kPa. Upper bound of PComOutletisspecified so that it does not exceed the pressure of inlet NG.