Agitating sluggish products improves discharge

Instead of using vibration or fluidisation methods to assist sluggish product discharge, a silo/hopper discharge aid encourages mass flow material discharge through mechanical agitation.

A new silo/hopper discharge aid is being offered to the UK market through Robin Engineering Services in North Staffordshire.

The Circle Feeder, as this new device is called, represents a new approach to the solution of extracting materials, particularly those which do not flow well or have a fibrous content from silos and storage hoppers, and was developed by materials handling engineers at the Yoshikawa Corporation in Japan, where there are more than 4000 such units now in operation.

Unlike traditional approaches to this problem, which use vibration or fluidisation methods to assist product discharge, the Circle Feeder encourages mass flow material discharge through mechanical agitation of the product.

Flat vanes, rotating slowly around the feeder shell, generate radial flow of the material beneath an annular ring.

This can be adjusted to control flow volumes.

Once in motion, peripheral rotating vanes guide product to one or more discharge ports for outfeed and further processing.

A fully controlled and metered flow of product is achieved through the height adjustment of the annular ring combined with the speed of rotation of the flat vanes.

Available in sizes up to 2.4 metres, a circular feeder is always selected to have a suitable diameter greater than the critical bridging diameter of the product being handled.

This, along with well distributed mass flow around the circumference, prevents arching or bridging in the silo and avoids flow disruption.

An added benefit with the circle feeder is that silo or storage hopper height can be reduced, since the circle feeder will allow the reduction or total elimination of the cone section of the storage unit.

Available as standard in mild steel or grade 304 stainless steel construction, a sanitary version can be supplied with highly polished contact surfaces and easy-to-clean access, and a mirror-finish version for GMP/clean room applications.

Furthermore, load cells and digital controls can be added for loss in weight applications where highly accurate material mass flow is critical.

These benefits, combined with its simple construction and easy to install design, have recently proved successful in securing two important contracts.

A major manufacturer of LCD glass screens selected a model CF1200 to ensure that his raw material mix, comprising glass cullett and fine powders of highly differing densities, did not segregate on discharge from storage and that a uniform mix was supplied to the start of his manufacturing process.

Similarly, a German company, producing bagged mortar mixes for DIY centres, selected a model CF2000, capable of supplying the mix to feed 2000 x 25kg.

bags per hour in a guaranteed homogenous state.

Other products, such as polymer flakes, soap powders, fertilizers, vegetable off-cuts, minced meat, carbon black, sewage sludge and paper pulp have also been handled with similar success.

Robin Engineering Services is a company dedicated to the supply of quality equipment, such as bucket elevators, automated guided vehicles, cooling spirals and other specialist items to solve materials handling problems and the Circle Feeder represents an ideal complement to its existing portfolio.

Typically, it underlines the Robin commitment to providing a quality design and supply service to customers old and new.

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