9. Reaction aspect

A chemical reaction, whether catalytic or involving convertible solids, is very often accompanied by a change in gas volume that can significantly alter the flow structure. This phenomenon is due, on the one hand, to the change in gas volume caused by heating (exothermic reactions) or cooling (endothermic reactions) and, on the other hand, to the expansion or compression of the gas volume. To better understand the role of the chemical reaction and its interaction with the hydrodynamic behavior of CFLs, we will discuss separately the two typical processes employing this contacting technique, namely the FCC process for catalytic reactions and the coal combustion process for convertible solids.