A Twin Fluid-Bed Reactor for Removal of CO2 from Combustion Processes

Degradation study of a novel polymorphic sorbent under realistic post-combustion conditions

“…One of the most promising CCS technologies is calcium looping [2]. The calcium looping process utilises calcium oxide to absorb and release CO2; the calcium oxide is cycled between a carbonator where CO2 is absorbed (eqn 1) and a calciner where CO2 is released (eqn 2) [3].…”

“…To overcome the endothermic calcination reaction and to increase the reaction rate a high temperature of around 900-950 °C is required. ΔH = +178 kJ/mol (2) Compared to other solid sorbents, such as hydrotalcites and zirconates, CaO has a significant advantage as its typical initial absorption capacity is ~0.79 g CO2/g sorbent (or carrying capacity [4]). …”

The impact of calcium sulfate and inert solids accumulation in post-combustion calcium looping systems

“…Postcombustion CaL was first proposed by Shimizu et al [10], and is based on the use of lime as a sorbent to capture CO 2 by means of carbonation/calcination cycles. The most suitable configuration for the application of CaL on a large scale involves the use of two interconnected circulating fluidized bed (CFB) reactors (carbonator and calciner as shown in Fig.…”

“…The partially carbonated solid stream enters the calciner together with a continuous make-up flow of limestone fed to this reactor to compensate for the decay of the CO 2 capture capacity of the sorbent with the number of carbonation/calcination cycles. In the calciner coal burns under oxy-fired conditions [10] to attain the temperatures required to convert both the CaCO 3 from the carbonator and the fresh sorbent back to CaO (around 900ºC). Although the heat demand in this reactor (coal and O 2 ) is high [10][11], the overall energy penalty of the CaL process is low [10,[12][13][14][15][16][17][18][19], since energy can be recovered from high-quality heat sources (the solids streams between reactors, the carbonator and the high temperature gases abandoning the reactors).…”

“…In the calciner coal burns under oxy-fired conditions [10] to attain the temperatures required to convert both the CaCO 3 from the carbonator and the fresh sorbent back to CaO (around 900ºC). Although the heat demand in this reactor (coal and O 2 ) is high [10][11], the overall energy penalty of the CaL process is low [10,[12][13][14][15][16][17][18][19], since energy can be recovered from high-quality heat sources (the solids streams between reactors, the carbonator and the high temperature gases abandoning the reactors). As a consequence of the nature of the CaL process, these systems have a continuous input of inert solids, mainly due to the coal fed into the circulating fluidized bed calciner but also because of the SO 2 in the flue gas entering the circulating fluidized bed carbonator.…”