Dynamic model of a pyrolysis furnace

Abstract

A dynamic model of a pyrolysis furnace is developed which takes account of the lags arising from the reactor coils, the radiation and convection combustion zones and the furnace refractories. The physical problem is analysed to find computational strategies for the numerical solution which overcome the inherent stiffness of the overall system equations. In order to be able to predict the product distribution during transient operation, it is essential to have a mechanistic-type kinetic model for the reactions, and the thermal processes must be capable of predicting the spatial distribution of temperature at any time. An examintion of the minimum level of detail to do this provides valuable insight as to how the observed dynamic responses can be explained in terms of the interaction of the characteristic fundamental processes. From this, it is possible to identify modes of operation which will not result in design limitations being exceeded, and enable safe procedures to be established for start-up and shutdown which can be interpreted in terms of the physicochemical processes.