Natural gas sweetening polymeric membrane: Established optimum operating condition at 70% of CO2 concentration feed gas stream

Abstract

PETRONAS embarks on breakthrough technology for natural gas sweetening in high CO₂ gas fields. Membrane technology is found to be one with high potential and a promising technology for bulk CO₂ removal from natural gas. It can be suited to wide operating conditions to process varied natural gas composition, pressure and temperature. This paper focuses on the extensive development of PETRONAS in-house membrane and its evaluation for gas separation performance for high CO₂ feed gas at different operating conditions; eg. feed gas flowrate, temperature, pressure, CO₂ concentration in mixed gas system, and permeate pressure. For all the cases in this study, samples were tested at optimum gas flowrate of 1000 standard cm³/min (sccm) to obtain representative membrane performance. Feed gas pressure and CO₂ concentration have shown significantly affect membrane permeation properties; whereas feed gas temperature and permeate pressure showed negligible impact. There is a trade-off between permeance and selectivity when CO₂ concentration is increased from 40% to 70%; where the CO₂ permeance increased by 12% which consequently reduces CO₂/CH₄ selectivity by 15%. In summary, the membrane developed in this study demonstrates high pressure durability up to 50 bar and temperature up to 55^oC with satisfactory gas separation performance in the presence of high CO₂ concentration in feed gas (up to 70% CO₂). This work is breakthrough in establishing the operational boundary of PETRONAS Membrane for technology development and deployment in monetizing high CO₂ gas field.