Seal Options for Rotary Dryers, Coolers, Kilns, and Drums

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Rotary dryers, rotary coolers, and rotary kilns are an integral part of the many industrial processes that shape our world. Their efficiency is key in maintaining a steady workflow and upholding quality standards. Seals help in sustaining an efficient and safe process. As a dryer, cooler, kiln manufacturer, FEECO offers a variety of seals, discussed below, for customers with rotary drum equipment.

The seals FEECO offers differ based on things such as the needs of the material being run, emission gases, and the internal gases. When air leakage into a rotary dryer, cooler, or kiln is not a major concern, the labyrinth seal is an option. The labyrinth seal is an economical option, with a relative leakage of >>1. This seal provides a torturous path for the ambient air by means of close clearance between the rotating seal ring and the stationary housing. With this seal, flexible wrap can also be added between the seal plate and rotating shell, in order to improve the seal.

The single leaf seal has a relative leakage of =1.0. This seal consists of a series of overlapping spring plates. Similar to a fanned out deck of cards, the leaves, or “cards,” are made out of spring steel, and are forced to push against the wear plate of the rotary drum. These fanned leaves naturally keep pressure on the rotating drum, keeping a good seal. There are also variations of this seal, such as the Double Leaf Seal, and the purged seal.

The double leaf seal has a relative leakage of =.25, and is used when less leakage can be tolerated than that of a single leaf seal. The double leaf seal consists of two single leaf seals with a ceramic fiber blanked sandwiched between the two leaves. With the double leaf seal, leakage is about 25% of a single leaf.

A purged seal, also known as a purged double leaf seal, is used in situations where even less leakage can be tolerated than that which a double leaf seal allows for. The purged seal has a relative leakage of =~0, and a relative leakage of purge gas of =0.5. This seal is made up of a pair of double leaf seals with a gas purge in the volume between the seals. The purge gas prevents the interior gas from exiting. A small amount of purge gas is lost both to the surroundings and the interior of the kiln.

After the purged double leaf seal, is the Bergmann seal. The Bergmann seal is used in situations where it is of the utmost importance that virtually no air leakage into the process can be tolerated. The Bergmann seal is a highly precise mechanical seal that uses spring-loaded packing rings to maintain the seal. Purge gas can also be used to ensure there is no leakage into or out of the rotary drum.

The graphite seal is FEECO’s latest innovation in seals. Spring tensioned graphite blocks are used to maintain the seal between the stationary housing and the rotating drum shell. The graphite seal is ideal when there is a potential for material to enter and degrade the seal, because the close contact of the graphite with the rotating surface prevents material from entering the seal. Additionally, the graphite seal can be used in high-temperature situations where other seals are not applicable.

Whether it is a rotary dryer, rotary cooler, or rotary kiln, FEECO International can provide seals to fit the needs of your system.

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