The heart of the dryer is the drum, constructed in cast iron and designed to accommodate high steam temperatures and pressures, precision machined to provide even heat transfer and hence reproducible performance over long periods. For products which may not come into contact with cast iron the drum may be hard chrome plated or chrome plated over nickel for even more arduous process conditions.

The drum rotates in either grease or oil lubricated heavy duty roller bearings which may be split to facilitate bearing replacements.

Materials may be fed to the dryer drums by a variety of mechanisms ranging from simple spray pipes for double drum dryers to traversing feed mechanisms with single or multi feed pipes for single cylinder feed roll dryers.

Product is removed from the dryer drum by means of an alloy steel doctor blade or knife rigidly clamped in a cast iron knife bar assembly. The knife is applied to the surface of the drum by pneumatic cylinders located at each end of the dryer. For improved life and reduced drum maintenance an oscillating knife system may be fitted with either conventional or disposable knives.

After removal from the drum the product is collected by a screw conveyor specially designed to break up the product film or flakes into easy-to-handle particles. For products that require cooling after removal from the drum, e.g. those with high sugar contents, air knives and film take-off rollers may be fitted.

To prevent leakage of the feed slurry from the dryer, pneumatically loaded damplates faced with suitable seal materials are provided at each end of the dryer drum or drums.

To minimise mechanical damage to the surface of the dryer drums, applicator (feed) rolls are mounted in spring loaded bearing slide assemblies designed to allow the rolls to lift in the event of a foreign body passing between the roll nips and dryer drum and return to their original position. In cases of twin cylinder dryers, one drum is fixed in position, the other is spring loaded to give the same degree of protection.

Dryers for food applications are generally provided with vapour canopies and extract systems to remove the vapours from the operating area. Dryers for hazardous materials may be provided with complete dust and fume tight enclosures whilst heat sensitive products may require full vacuum casings.

For double or twin cylinder drum dryers the drive is provided by means of spur pinion and gear wheels mounted on the dryer drum drive end trunions. In the case of drum dryers with multi feed or applicator rolls, each applicator roll is rotated by a pinion driven by the drive spur gear wheel. In the case of drum dryers with simple applicator rolls the applicator roll is often driven by a completely separate drive train. All drives are variable speed, type and configuration to suit each particular application.

DRUM DRYERS - Construction and Operation - Feed Systems - Optional Equipment
Machine Sizing - Materials Processed

Details of - Drum Flakers - Tubular Dryers & Coolers -
Rotary Dryers & Coolers - Calciners

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