REACTION-MECHANISMS OF DRY CA-BASED SORBENTS WITH GASEOUS HCL

The mechanisms of HCl reaction with dry Ca(OH)(2) or CaO sorbents in f lue gas cleaning applications were investigated by differential scanni ng calorimetry (DSC), thermogravimetry, and X-ray diffraction, A short -time differential reactor (STDR) was used to contact 1000 ppm HCl wit h dry sorbents at temperatures ranging from 100 to 600 degrees C. The product of HCl reaction with Ca(OH)(2) over the 100-600 degrees C rang e in the STDR was identified as a solid solution of CaCl2.2H(2)O and C aClOH. Subsequently, the Cl/Ca molar ratio in the product was determin ed to be less than 2. The product of the HCl reaction with CaO in the STDR over the 100-600 degrees C range was identified as CaClOH. When s canned by DSC, samples of both CaO and Ca(OH)(2) that were previously exposed to HCl in the STDR revealed an endotherm between 530 and 590 d egrees C. The amount of enthalpy correlated well with the chemically d etermined sample conversion.