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Information Of The Main Components Of Rotary Kiln

The basic components of a rotary kiln are the shell, the refractory lining, support tyres and rollers, drive gear and internal heat exchangers.Kiln shell this is made from rolled mild steel plate, usually between 15 and 30 mm thick, welded to form a cylinder which may be up to 230 m in length and up to 6 m in diameter.This will be usually situated on a east/west axis to prevent eddy currents.Upper limits on diameter are set by the tendency of the shell to deform under its own weight to an oval cross section, with consequent flexure during rotation.Length is not necessarily limited, but it becomes difficult to cope with changes in length on heating and cooling if the kiln is very long.Refractory lining the purpose of the refractory lining is to insulate the steel shell from the high temperatures inside the kiln, and to protect it from the corrosive properties of the process material.It may consist of refractory bricks or cast refractory concrete, or may be absent in zones of the kiln that are below around 250°c.The refractory selected depends upon the temperature inside the kiln and the chemical nature of the material being processed.In some processes, such as cement, the refractory life is prolonged by maintaining a coating of the processed material on the refractory surface.The thickness of the lining is generally in the range 80 to 300 mm.A typical refractory will be capable of maintaining a temperature drop of 1000°c or more between its hot and cold faces.The shell temperature needs to be maintained below around 350°c in order to protect the steel from damage, and continuous infrared scanners are used to give early warning of "hot-spots" indicative of refractory failure.Tyres and rollers internal heat exchangers heat exchange in a rotary kiln may be by conduction, convection and radiation, in descending order of efficiency.In low-temperature processes, and in the cooler parts of long kilns lacking preheaters, the kiln is often furnished with internal heat exchangers to encourage heat exchange between the gas and the feed.These may consist of scoops or "lifters" that cascade the feed through the gas stream, or may be metallic inserts that heat up in the upper part of the kiln, and impart the heat to the feed as they dip below the feed surface as the kiln rotates.The latter are favoured where lifters would cause excessive dust pick-up.The most common heat exchanger consists of chains hanging in curtains across the gas stream.Spiral separator : http://www.Hxjq-crushers.Com/15.Htm sand maker : http://www.Mine-crusher.Com/sandmaker.Htm.

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