Robust control of Propane Pre-cooled mixed refrigerant process for natural gas liquefaction

Natural Gas are often found at remote locations to bring it to the world market liquefaction is required. In liquefaction natural gas is cooled to around -160°C, hence required considerable amount of energy. To maximize the profit from the existing design it is necessary that the process should operate efficiently, reliably and safely. Hence a good and Robust control is required. Due to tight control strategy the stability is an issue in the main cryogenic heat exchanger(MCHE) and in the Refrigerant flash drum. In this study the C3MR process was considered and the dynamic model was made in Hysys simulator and used to implement the proposed control algorithm. By judiciously choosing control variables we have proposed more robust control strategy and its performance was observed under simulation environment which provide satisfactory robustness for stability and performance.