On the Use of Steady-State Optimal Initial Operating Conditions for Control Scheme Implementation of a Fixed-Bed Fischer–Tropsch Reactor

A control scheme implementation for a fixed-bed Fischer–Tropsch synthesis (FTS) reactor using the optimal initial operating conditions at steady-state is developed. The proposed approach consists of solving a nonlinear constrained optimization problem for a fixed-bed FTS reactor with incorporation of a control scheme in the cooling jacket in order to find the optimal values of the initial operating conditions of temperature, gas-hourly space velocity (GHSV), pressure and coolant flow velocity under a steady-state regime that maximizes CO conversion and C 5 + product selectivities. Such optimal operating conditions at steady-state are used to evaluate the dynamic behavior of the reactor under the proportional-integral control (PIC) scheme action that is implemented in the cooling jacket. An extended dynamic one-dimensional pseudohomogeneous model of a fixed-bed FTS reactor recently reported in the literature is used. The obtained results show the importance of the implementation of dynamic control strategies for the FTS carried out in a fixed-bed reactor, since they allow for ensuring the thermal control of such highly exothermic reactions and assure better reactor performance in terms of high CO conversion and liquid products selectivity (C 5+ ).