Energy penalty reduction in the calcium looping cycle

Abstract

Despite the interest of carbon capture and storage research on the calcium looping cycle due to the potentially low CO2 avoided cost this technology offers, there is a need to keep on reducing both cost and system size to ensure the economic advantage of this technology. This work presents three novel calcium looping configurations designed with the objective of decreasing the fuel consumption in the regeneration reactor and the energy requirements in the air separation unit. Available heat from the solid and gaseous streams leaving the calciner is used to heat up the particles before entering this reactor. These systems are thermodynamically modelled and their thermal efficiencies and available energy flows analyzed to establish which configuration has the higher coal and oxygen consumption saving potential. The configuration that includes an extra heat recovery bed to exchange heat between the CO2 stream and the solid particles entering the calciner presents the lowest coal and fresh sorbent consumption in the regeneration step. As a consequence, smaller system size and operational cost may be achieved with this configuration. Since fuel requirements are reduced, so does the oxygen demand from the air separation unit which will introduce less energy penalties associated to its high specific electrical consumption.