FACTORS AFFECTING THE THERMOGRAVIMETRIC TECHNIQUE IN THE CHARACTERIZATION OF SORBENTS FOR AFBC

Thermogravimetric analysis (TGA) is a technique usually employed for characterization of sorbents used in fluidized-bed coal combustors. Different sorbent characterization studies by TGA display great differences depending on the experimental conditions used. Mercury porosimetry and sulphation experiments made with calcined sorbents indicate that sorbent reactivity is strongly affected by the calcination conditions. In this paper, the effect of the experimental technique (sample heating rate, time before sulphation, CO2 concentration and sorbent particle size) on the sulphation is analysed. Such effects were stronger in limestones with small pores due to the sinterization effect. In addition, limestones with large pores showed the greatest capacity to react with the SO2. A set of experimental conditions for the characterization of sorbents in order to obtain reliable results is proposed.