The presence of CaS in the combustion chamber of a 12 MW circulating fluidized bed boiler

Artikel i vetenskaplig tidskrift, 1995

The presence of CaS in bed ashes from a circulating fluidized bed boiler (CFBB) has been studied. The boiler was operated with an excess air ratio of 1.2 but with varying air staging and at temperatures of 850°C and 930°C. The fraction of sulphide sulphur to total sulphur varied between 1 and 4%, with the higher sulphide contents found during intensified staging, that is, when the fraction of air supplied to the bottom bed was low. Under conditions with high SO2 concentrations, due to stopped limestone addition, sulphide to total sulphur fractions of up to 16% were found. In conclusion, a high SO2 concentration, especially in conjunction with intensified air staging, constitutes a risk factor for CaS formation.