Deactivation model for dry desulphurization of simulated flue gas with calcined limestone in a fluidized-bed reactor

摘要

In this work, dry desulphurization of simulated flue gas was investigated in a laboratory-scale stainless steel fluidized-bed reactor (46 X 500 mm~2) by using calcium-containing local Turkish limestone (Karaagacli/MUS) which was calcined at 900℃ with 5% H_2O vapour. The fluidized-bed reactor (FBR) was operated batchwise with a single charge of (15 g) particles for obtaining SO_2 breakthrough curves. Experiments were carried out at different temperatures (600 ≤ T ≤ 900℃) and SO_2 feedstock concentration (1000 ≤ C ≤ 6000 ppmSO_2) within the range of space velocity (10,000 ≤ v ≤ 30,000 h~(-1)). In addition, the effects of other components (O_2, CO_2, H_2O) in flue gas were investigated on the SO_2 breakthrough curves. The deactivation model (DM) was tested for these curves by using the analogy between calcined limestone sulphation and the deactivation of catalyst particles. Observed surface reaction rate constant (k_S) and first order deactivation rate constant (k_d) were obtained from the model. It was found that the DM allows a good description of the experimental breakthrough curves without having to resort to prohibitively lengthy computer calculations compared to the so-called grain model (GM) and random pore model (RPM).