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AIM :

To determine the drying characteristic for rotary dryer.

INTRODUCTION :

The rotary dryer is a type of industrial dryer employed to reduce or minimize the liquid moisture content of the material by bringing it in direct contact with a heated gas.The dryer is made up of large rotating cylinder which slopes slightly so that the discharged end is lower than the material feed end in order to convey the material under gravity.Material to be dried enters the dryer and as the dryer rotates,the material is lifted up by a series of internal fins lining the inner wall of the dryer.When materials fall back to the bottom,it passes through the hot gas stream.In the experiment , the gas stream moves towards the feed end from the discharge end (counter current flow).Also the material passes through the length of the dryer at nearly the wet - bulb temperature.

Single pass and three pass rotary dryers are ideal for high moisture, friable, free-flowing products. The Aeroglide Rotary dryer is the choice for high throughput capacity applications involving high moisture, friable, free-flowing commodity products and by-products. A rotating drum and strategically positioned flights combine to lift and shower product evenly through the air stream. Thermostatically controlled discharge air temperature assures precise final moistures and great sensitivity to varying product conditions. Single-pass or three-pass configurations are available to match product characteristics. Heating options include steam, gas, oil, thermal oil and auxiliary biomass burner system.

DESCRIPTION :

A rotary dryer consists of a cylindrical shell, set with its axis at a right angle to the horizontal and mounted on rollers so that it can be rotated.The material to be dried is fed to the high end of the dryer and , by rotation of the dryer, usually assisted by internal shelves of flight , is gradually advanced to the lowew end where it is discharged. The source of heat for a rotary dryer is usually the hot air that circulates through the dryer.The characteristic dimensions are :

Rotary dryer ID = D =110 mm = 0.11 m

Dryer length = 1500 mm = 1.5 m

Pre - heating of air using 1.5 KW heater (2 nos)

Air flow rate measurement by a pitot tube

Solid feed : By a screw conveyor

Inlet / Outlet air temperature by a hygrometer.

EXPERIMENTAL SETUP :