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in Wiley Online Library (wileyonlinelibrary.com).Calcium looping is an energy-efficient CO 2 capture technology that uses CaO as a regenerable sorbent. One of the advantages of Ca-looping compared with other postcombustion technologies is the possibility of operating with flue gases that have a high SO 2 content. However, experimental information on sulfation reaction rates of cycled particles in the conditions typical of a carbonator reactor is scarce. This work aims to define a semiempirical sulfation reaction model at particle level suitable for such reaction conditions. The pore blocking mechanism typically observed during the sulfation reaction of fresh calcined limestones is not observed in the case of highly cycled sorbents (N > 20) and the low values of sulfation conversion characteristic of the sorbent in the Ca-looping system. The random pore model is able to predict reasonably well, the CaO conversion to CaSO 4 taking into account the evolution of the pore structure during the calcination/carbonation cycles. The intrinsic reaction parameters derived for chemical and diffusion controlled regimes are in agreement with those found in the literature for sulfation in other systems.

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Calcium looping is a post-combustion CO 2 capture technology that uses CaO as a regenerable solid sorbent. One potential advantage of this technology is that it allows flue gases to be treated with SO 2 , avoiding the need for a costly desulfurization step. In this work, we study the desulfurization capacity of a CFB carbonator reactor in a 30 kW th pilot plant that has been used to test CO 2 and SO 2 co-capture. A simple reactor model is applied to analyze the experimental results obtained and to study the effect of the main variables involved in the process: i.e. the circulation rates of solids and the inventory of active material in the CFB reactor.The results obtained have shown that SO 2 capture efficiencies above 0.95 can be achieved in a CFB carbonator even when using a low inventory of active material in the bed. Extreme 2 desulfurization (SO 2 emissions below 5-10 ppmv) is thought to be achievable in large scale CFB carbonators designed to capture CO 2 with CaO.

The sulfation reaction rate of CaO particles in three reactors comprising a postcombustion calcium looping system is discussed: a combustion chamber generating flue gases, a carbonator reactor to capture CO 2 and SO 2 , and an oxy-fired calciner to regenerate the CO 2 sorbent. Due to its strong impact on the pore size distribution of CaO particles, the number of carbonation/calcination cycles arises as a new important variable to understand sulfation phenomena. Sulfation patterns change as a result of particle cycling, becoming more homogeneous with higher number of cycles. Experimental results from thermogravimetric tests demonstrate that high sulfation rates can be measured under all conditions tested, indicating that the calcium looping systems will be extremely efficient in SO 2 capture.