ANALYSIS AND VALIDATION OF A SIMPLIFIED MODEL OF A WET FLUE-GAS CLEANING SYSTEM

Combustion of waste produces large variations in flue gas composition. These variations lead to dynamic effects in the emission control syst em. Variations in scrubber liquid pH is a typical effect, influencing the absorption of pollutants. A dynamic model for a wet system for SO2 removal was built using an existing plant in Hobro, Denmark as a mode l system. An experimental validation showed that the model has a good agreement with operating data. There was one important limitation to m odel performance. The absorption of HCl were not modelled and the expe riments proved this to be an important process characteristic. A linea r analysis of the model showed that the process is approximately a fir st order system. The process gain is however changing with changing ch emical composition of the scrubber liquid, which makes a robust contro ller design hard to achieve. Some concluding remarks are made on plant and control system design. (C) 1997 Elsevier Science Ltd.