Demonstration of a calcium looping process with internal regeneration of the reaction enthalpy in a pilot-scale reactor

Compared to known Carbon Capture processes, a packed bed pressure-swing process design for Calcium Looping can achieve a very high energy efficiency, which results from the ability of reactor-internal regeneration of the reaction enthalpy of the exothermic carbonation reaction. The theoretical process concept relies on a number of assumptions which have not been proven experimentally so far. Particularly, it must be shown, that a thin reaction front is formed during the carbonation phase and that the calcination is feasible without any external heat supply using only the sensible heat stored in the sorbent particles. For this purpose, cyclic experiments are conducted in a pilot-scale packed bed reactor filled with burnt dolomite under conditions of CO 2 partial pressure-swing with carbonation at 1 bar CO 2 and calcination at 0.2 bar CO 2 . The reaction process is monitored by a matrix of thermocouples installed in the packed bed. Additionally, the CO 2 volume fraction at the reactor outlet is measured continuously to determine a balance of the CO 2 bound and released. In total, 21 cycles of carbonation and calcination were performed, proving that no external heat supply was necessary for the calcination cycles. The reaction front during carbonation was narrow, with a width of roughly 11 % of the bed height. In total, more than 100 kg of CO 2 are bound and released. It is also shown that heat losses lead to a continuous deactivation of the sorbent at the outer edge of the packed bed which reduces the reactor performance.