Attrition study of cement-supported biomass-activated calcium sorbents for CO2 capture

Abstract

Enhanced CO2 capacity of biomass modified Ca-based sorbent has been reported recently, but undesired attrition resistance has also been observed. Cement was used as a support for biomass-activated calcium sorbent during the granulation process in this study, in order to improve the poor mechanical resistance. Attrition tests were carried out in an apparatus focused on impact breakage to evaluate how the biomass addition and cement support influence the particle strength during Ca-looping. Results showed biomass addition impaired the mechanical strength and cement support could improve it, which is reflected by the breakage probability and size change after impact of pellets experienced calcination and multiple calcination/carbonation cycles. Larger-sized particles suffered more intense attrition. The mechanical strength of sorbents declined significantly after higher temperature calcination but increased after carbonation. After multiple cycles, the mechanical strength of particles was greatly enhanced, but more cracks emerged. A semi-empirical formula for calculating average diameter after attrition based on Rittinger’s surface theory was developed. Observation on the morphology of particles indicated that particles with more porosity and cracks were more prone to breakage.