Heat integration of alternative Ca-looping configurations for CO2 capture

The best option to overcome the energy penalty in Ca-looping is to take advantage of the surplus heat by external integration to produce additional power and increase net efficiency. As calciner represents the main energy consumption, another possibility is to internally use the surplus heat to preheat the solids entering this reactor. The objective of internal integration is to reduce the energy demand per captured tonne of CO2. It represents a reduction of the coal and oxygen needs and also a total decrease in the CO2 generation regarding the ordinary configuration. However, the amount of available heat for extra power generation by external integration, essential for the viability of this technology, is also reduced. This is the case of the configurations including a cyclonic preheater or a mixing seal valve. This study assess the energy penalty minimization that may be reached by external integration of these internal energy integration configurations. A methodological process has been applied to obtain a reduction of the energy penalty with respect to the ordinary configuration. This energy saving combined with the lower size of equipment and reduced capital cost would make the cyclonic preheater the most suitable configuration to improve the viability of this technology. (C) 2016 Elsevier Ltd. All rights reserved.