Thesis for the Degree of Master of Science


Year 2003
Seppo Nevalainen

Dynamic modeling and simulation of the alumina calcination process for control optimisation

Circulating Fluid Bed (CFB) reactor is the key component in the alumina calcination process. Alumina temperature and retention time in the CFB are the most important variables of the process and affect strongly the specification of end product. Steady temperature at the required level provides calcined alumina with the uniform product quality and other favourable properties for further processing.

The aim of this thesis was the steady state and dynamic modeling and simulation of the alumina calcination process. Using dynamic simulation, development of the temperature control of the CFB reactor was investigated. The traditional temperature control applies PI-controllers to adjust the temperature. As an alternative, a combined feedforward-feedback control structure that uses a static pressure process device and the CFB temperature to adjust the reactor heat input was also considered.

In the literature part of this thesis, alumina production - specifically alumina calcining - process was introduced as well as other CFB based technologies. In addition, the thermodynamic equations used in the calculation of physical properties for the simulation model were presented. Finally, an introduction to commercial simulation softwares was given. In the experimental part the unit operations of the alumina calcination process were examined and the features of the simulation software were presented. The test simulations were performed and comparison between both control strategies were made.

The simulation results showed that both control structures operated well in most of the disturbance situations as long as the controllers had been tuned properly.

This info last modified 16 Jul 2018 by Jerri Kämpe-Hellenius