Modeling calcium looping for CO2 capture with a solar energy-driven calciner

Calcium Looping (CaL) is an interesting post-combustion CO2 capture and storage technique, but it requires the operation of an endothermal calciner through the oxy-combustion of an auxiliary fuel. The idea behind the present work is to couple a CaL process with a concentrated solar power system, in order to supply all the thermal energy required by the calciner through a renewable source. The integration of a CaL cycle with a concentrated solar power system would offer many technical, economical and environmental advantages. This integration must however account for the absence of solar energy during the night. Therefore, in the present work a process with some peculiarities has been designed, including two additional storage vessels, and making use of a different looping strategy between day and night. A model of the described system has been here developed. It consists of a population balance model on the sorbent particles in the whole system, during both day and night operation, which also takes into account the occurrence of sorbent attrition/fragmentation. The influence of the main operating parameters (sorbent residence time, sorbent/CO2 inlet molar ratio, fluidization velocity) on the CO2 capture efficiency in the carbonator, on the sorbent loss by elutriation and on the calciner thermal power demand is assessed, together with a discussion concerning the solar power system integration, with an indication of the required surface of the heliostats field per bed cross-sectional area.