Rotary kiln can be either of the direct-fired type, or the
indirect-fired type. In a direct-fired kiln, a fuel is burnt in the
drum, and the material is processed through direct contact with the
flue gas. In an indirect-fired kiln, material is processed in an
inert environment, and is heated through contact with the shell of
the kiln, which is heated from the outside to maintain an inert
environment.
The furnace walls (normally lined) make intermittent contact with
the flue gas and the charge. Heat required for the various physical
and chemical processes is delivered to the charge by lifting and
overturning the charge as it moves through the interior of the
rotary kiln
The shell of the kiln is made of mild steel plate. Mild steel is
the only viable material for the purpose, but presents the problem
that the maximum temperature of the feed inside the kiln is over
1400°C, while the gas temperatures reach 1900°C. The melting point
of mild steel is around 1300°C, and it starts to weaken at 480°C,
so considerable effort is required to protect the shell from
overheating.
Professional Rotary Kiln Manufacture.pdf
Rotary kilns (sometimes called calciners or rotary furnaces) are
used for thermal treatment processes such as calcination,
sintering, pyrolysis and firing, as well as for oxidation and
reduction. These treatments can be applied to powders, granulates,
suspensions and green bodies. A rotary kiln consists of a
cylindrical, rotating body mounted between stationary material feed
and outlet housings. The constant turning of the kiln body mixes
the material, ensuring that it is processed homogeneously. Rotary
kilns are heated either directly (inside the kiln chamber) or
indirectly (from outside), depending upon the requirements of the
application.
Calcination Materials Cement Aluminate Cement Limestone & Lime sludge Pet coke Calcination Minerals i.e. Bauxite and Iron Ore Sponge Iron Dolomite Kaolin Mica LECA Bauxite Oil Proppant Other materials | Specifications Diameter: 1000mm to 4500mm Length: 12000mm to 130 000mm Methods of heating: Direct or indirect Capacity: 200kg/h to 210t/h Fuel: coal, natural gas, heavy oil, etc Temp range: 900- 1400°C Material: Carbon steel, Stainless steel, etc Thickness: 12mm to 100mm
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