A process design and control strategy for dimethyl ether production from a methanol feedstock

With ever tightening vehicular emission regulations, alternative fuels to diesel are being developed. One such alternative is dimethyl ether (DME) which has a performance similar to diesel while at the same time meeting or exceeding the current emission regulations. A plant wide control strategy for a DME plant is presented. The dynamic response of the plant to expected disturbances using a conventional multiloop PID control scheme provided adequate control. However, set point tracking of the water methanol column bottoms product composition controller was inadequate, resulting in considerable interaction between the column temperature and composition control loops. The implementation of a model predictive controller (MPC) on the column improved set point tracking but resulted in poorer disturbance rejection.