HSS anions reduction combined with the analytical test of aqueous MDEA in South Pars gas complex

Abstract

Heat stable salts (HSS) form in amine systems as a result of the reaction products of the amine and acidic compounds stronger than H2S and CO2 in the inlet stream to the gas treating unit (GTU). These stable salts are not readily disassociated and removed in the regeneration column. Increased foaming and reduced acid gas carrying of amine solution capacity are results of HSS present in an amine system. In this study, in-depth analyses of degradation compound, HSS anions, metal cation content, BTEX content, mercaptane content, acid gas loading, and foaming tendency of contaminated and treated Methyldiethanol amine (MDEA) solutions were performed to specify the design specific parameters of ion exchange resin system for handling more than 487.61 m3 of contaminated MDEA solution containing a total of 9000 ppm wt of HSS. The ion exchange resin plant design and construction were considered as an alternative method to the MDEA treatment to reduce degradation of the MDEA. Ion exchange resin was based on a strong anionic resin (LEWATIT MP 800). Ultimately, the analytical results exhibited a significant reduction of HSS in the MDEA solution. The equilibrium adsorption studies for anions reduction were fitted into the Langmuir, Freundlich model isotherms. The Langmuir and Freundlich equilibrium isotherms explained the best performance of ion exchange resin with the predicted qmax value of 370.37 mg/g by the Langmuir model. The breakthrough time for removal of anions in ion exchange resin bed with a flow rate of 5.5 × 10−4 m3/s was achieved within 6948s.