Automated process design of acid gas removal units in natural gas processing

• A new superstructure optimization approach is introduced for natural gas sweetening.
• Simultaneously considering multiple different structural modifications.
• Few previous studies have considered the optimization of structural options.
• The new superstructure includes more design options than those in previous studies.

This study looks at the design of the acid gas removal unit (AGRU) for natural gas processing. For the purpose of enhancing energy efficiency a number of different structural options are considered including multiple feeds, semi-lean and pump around modifications in addition to modification of operational parameters. Previous studies in this area have considered the comparison of different individual configurations but there has been a lack of research considering the simultaneous optimization of equipment configuration. Hence, in this study a superstructure-based optimization approach is used to simultaneously identify the most appropriate arrangement and operating conditions while the maximum energy recovery potential is also realized with the aid of energy composite curves (ECC). This methodology is applied to a case study where it is shown that the optimal configuration contains a combination of pump around and semi-lean process modifications allowing a 15.9% reduction of utility costs.