Wet kilns are those that are usually fed with slurry materials. Wet kilns
are usually long with kiln lengths on the order of 150–180 m (about
500–600 ft). The feed end is usually equipped with chains that serve
as a heat “flywheel” by recuperating the heat in the exhaust gas for
use in preheating the feed to assist the drying. Chains are also used
to break up any lumps that the material might form during the transition phase of changing from slurry to solids upon drying. In the
cement industry these kilns are often not efficient and are becoming
a thing of the past replaced by long dry kilns. Nevertheless, there are
certain applications that are not amenable to the alternative use of
long dry kilns, for example, lime mud kilns found in the pulp and
paper industry and some food applications