Fluidized bed calcium looping cycles for CO2 capture under oxy-firing calcination conditions: Part 2. Assessment of dolomite vs. limestone

The CO2 capture performance and the attrition behavior of a dolomite were assessed during calcium looping cycles in a lab-scale fluidized bed. Results were compared to those obtained with limestone in similar tests. The experiments were carried out under alternating calcination-carbonation conditions representative of a process with calcination in an oxy-firing environment (T = 940°C, 70% CO2), without or with the presence of SO2 at two concentration levels. Results showed that the CO2 capture capacity of the dolomite was larger than that of limestone, in spite of the lower calcium content of this sorbent. In fact, the large magnesium fraction in the dolomite reduced particle sintering and preserved the Ca reactivity. However, the presence of SO2 at both concentration levels significantly depressed the sorbent CO2 capture capacity. Contrary to limestone, the dolomite was subject to extensive attrition and fragmentation.