Sorbent/ash reactivation for enhanced SO2 capture using a novel carbonation technique

A novel process has been developed for reactivation of partially utilized calcium-based sorbents for increased SO2 removal and sorbent utilization from coal-fired boilers/combustors. Spent sorbent and combustor ash samples are treated under specific conditions to modify their internal structure and expose the under-utilized calcium for further SO2 capture. The reactivated sorbent shows a significant improvement in utilization, increasing from less than 45% to nearly 100%. Application of this novel reactivation process to ash samples obtained from a circulating fluidized-bed combustor also shows a marked improvement in utilization of available calcium, nearly doubling the amount of sulfur captured. The reactivation process involves carbonation of the unsulfated calcium. Better redistribution and exposure of the available calcium by the carbonation reactivation process, as compared to reactivation via hydration, is proposed as the main factor in increasing the sorbent utilization. The increased ultimate sorbent utilization obtained by this reactivation process could significantly improve the sorbent-based flue gas desulfurization technology.