Modeling and optimal control of conversion section of styrene plant to overcome effect of catalyst deactivation on production capacity

In this research, a pseudo steady state model is developed based on the mass and energy balance equations to simulate conversion section of a styrene monomer production plant. The conversion section includes three radial flow reactors in series, equipped with inter stage coolers. Typically, dehydrogenation catalyst experiences deactivation due to loss and migration of promoters, and increasing temperature and steam flow rate are practical solutions to prevent production decay in the plant. In the first step, accuracy of the simulation results is proved against plant data. Since there are different paths to overcome catalyst decay and maintain production capacity at desired level, the main challenge is selection and sequence of manipulated variables to control production capacity considering minimum effort. In this research, a real time optimization strategy is proposed to calculate the optimal trajectory of manipulated variables to control production and selectivity at desired level based on the optimal control theory. The optimization results indicated applying obtained optimal trajectories on the system increases production capacity about 16.13%.