ABSTRACT
n case one wants to predict the temperature profile in a chemical reactor, it is not sufficient to look for a simple relationship between reactor outlet temperature and the input variables such as flow and temperature – the model has to be more detailed. An on-line model should also have a minimum number of unknown parameters. This is essential for the adjustment to changes in process behavior, for example, decay in catalyst activity or decrease in heat transfer due to fouling. The checking and supervision can be done by an on-line computer. If the process operation has a dynamic character, the tolerance limits will change as a function of time. The design of a theoretical model usually starts with writing down the conservation laws resulting in momentum, material, and energy balances. Theoretical models have to be compared to empirical data. It is possible that only the values of parameters have to be adjusted.
