Ceramic and Calcination Kilns
Firing Kilns include roller and rotary kilns. A roller heart kiln is a kiln that has a conveyor to move product through the kiln instead of kiln cars. The roller hearth is a continuous kiln the same as a tunnel kiln and the air flow pattern inside the roller hearth kiln is the same as a tunnel kiln in that most of the heat is put into the center of the kiln and the exhaust gases are pulled toward the entrance end, counterflow to the product movement.
Rotary kilns are heat exchangers in which energy from a hot gas phase is extracted by the bed material. During its passage along the kiln, the bed material will undergo various heat exchange processes, a typical sequence for long kilns being drying, heating, and chemical reactions that cover a broad range of temperatures. Most kilns allow direct contact between the freeboard gas and bed material. The most common configuration is counter current flow whereby the bed and gas flows are in opposite directions although co-current flow may be utilized in some instances, for example, rotary driers.
