Simulation of the transient behaviour of a pilot plant fixed-bed reactor

Abstract

A model for a specific pilot plant has been set up using experience gained from simulation studies with general model types. The model consists of two parts — one describing slow changes in temperature and reactant concentration (SM) and another describing the fast propagation of concentration changes until a quasistationary state (FM). In this manner the dynamic simulation studies can be performed using a relatively small computer time. The simulations show that the FM period is extremely small (2–3 sec) compared to the SM period (1000–1500 sec). Furthermore it is shown that a disturbance in inlet temperature may cause an increase in reactor temperature that far exceeds the adiabatic temperature rise. With a sine disturbance in inlet temperature it is also observed that the wave keeps the sinusoidal shape in the reactor but the mean value at a distinct position is removed to a value higher than the stationary one.