Optimize capacity and efficiency for an amine unit

M. Pieronek, P. Krouskop and B. Burr, Bryan Research and Engineering Inc., Bryan, Texas; and S. Kitsatienkun, PTT, plc, Rayong, Thailand The removal of carbon dioxide (CO2) from natural gas is a necessary treating step prior to cryogenic processing. At PTT’s Gas Separation Plant No. 5 (GSP5) in Rayong, Thailand, the wellhead gas has CO2 concentrations ranging from 19 mol% to 23 mol%. This gas feeds an amine sweetening unit, where most of the CO2 is removed. The sweet gas product is dried before entering a cryogenic demethanizer, where ethane and heavier NGL are recovered. The demethanizer overhead reaches temperatures as low as –100°C to –120°C. To prevent CO2 freeze-out, the CO2 concentra