Multi–Compartment Fluo Solids Reactor is a three stage unit where hot gases from the main calcining compartment are used to dry and preheat calciner feed. The Fluo Solids Reactor usually consists of a reaction bed and one or more heat exchange beds for heat recovery. The Fluo Solids Reactor offers the facility of directly injecting the fuel into the reaction compartment. The Multi–Compartment Fluo Solids Reactor also comes with fluid bed spray coolers to further cool product solids for ease of handling.