Acid Aided Regeneration in Amine Treating: How Effective is it?

Klinkenbijl, Jeanine (Shell Global Solutions International B.V) | Brok, Theo (Shell Global Solutions International B.V) | Critchfield, Jim (Shell International Exploration and Production Inc) | Valenzuela, Diego (Shell International Exploration and Production Inc) | Lee, Danmi (Shell Global Solutions International)

OnePetro 

The development of more complex energy sources is increasing to meet the growing demand for more energy. Such gas resources may be more contaminated, more complex, more costly, and contain more CO2 and H2S. At the same time, tighter environmental and product specifications necessitate smarter gas processing. This needs to be achieved by stretching current processes and developing reliable new technologies to effectively address the challenges of managing complex gases.

One area of gas processing that is well established is Acid Aided Regeneration (AAR) technology: the use of acids to reduce the regeneration steam of amine treating units has been applied since the 1960s, and is nowadays often referred to as a Formulated amine. Or, achieve a lower specification in the treated gas, due to a lower leanness in the solvent when the regeneration heat is kept constant, and thereby reduce environmental (CO2 and/or SO2) emissions.

Shell has carried out an extensive study on the use and misuse of AAR, focusing on the actual effects in operation and comparing unit performance with results of process simulation in the presence of acids in an amine solvent.

The operational effects observed are explained and general guidelines for application discussed. Although the focus of the application is on low pressure selective design (Tail Gas Treating Units), the main effects for high pressure application are also addressed in the study. In the paper the basis for the Shells AAR technology is described:

Detailed analysis of process performance (both analytical solvent analysis and actual plant performance data) in aqueous amine treating units in a wide variety of applications. This gives good and consistent insight in the qualitative and quantitative results of acid addition to amine solvents and measured contaminant removal.

A theoretical discussion on the acid effects in an amine solution, focusing on the energy for regeneration of the amine, as well as the option to meet a lower contaminant specification with a constant regeneration energy requirement by the addition of an acid to the amine solution.