Preparation of bagasse ash/CaO/ammonium acetate sorbent and modelling their desulphurization reaction

The influence of siliceous and hydration agents additives on the preparation of calcium-based sorbents for dry flue-gas desulphurization at low temperature was studied. The key reaction variables investigated are: quantity of bagasse ash, hydration temperature, quantity of ammonium acetate and hydration time. Their effect on the surface area of the sorbent was determined and a central composite design was used as a statistical tool. A polynomial model was established to correlate the sorbent preparation parameters to the sorbent surface area. The desulphurization experiments performed with the thermogravimetric analyser indicate higher SO₂ removal when bagasse ash and ammonium acetate are used. The kinetics of desulphurization reaction was fitted using the unreacted shrinking core model and the results show that the rate-limiting step was diffusion over the product layer.