Compact screen separator allows installation of pneumatic conveyor

A compact, circular vibratory screener required 25 percent less headroom than a conventional circular screener, and 85 percent less floor space than a rectangular shaker screen of equivalent capacity, enabling Taber's Products Inc., Henrietta, MO, to fit both the screener and a pneumatic conveyor in a space previously occupied by an auger conveyor. The company packages plastic regrind powder in 3 to 12 ounce bags which are sold for balancing truck tires in a novel manner; the powder is blown into the tire and responds to its rotation by shifting to the position where weight is required for balance. This innovative method is said to overcome the inability of rim-mounted weights to properly or continuously balance a tire whose shape is distorted by high vehicle weights.

Taber's Products receives the plastic regrind powder in 1800 pound bulk bags which are loaded into a bulk bag discharger. A rigid auger conveyor was originally employed to transport the material 50 feet to a packaging machine, but dusting and spillage occurred through the auger trough lids which aroused OSHA air quality and safety concerns, prompting the conversion to a pneumatic conveying system with dust collector.

The company also needed to remove oversize particles from the regrind which could damage the packaging machine and clog air nozzles used to inject the powder into tires. However, the 26 inch vertical space available beneath the bulk bag discharger outlet and the restricted floor space were insufficient to accommodate both a pneumatic conveyor system and a conventional vibratory screener.

A rectangular shaker screen under consideration required 32 square feet of floor space and 48 inches of headroom. A circular vibratory screener consumed 85 percent less floor space, but exceeded the height restriction by almost one foot.

At only 24 inches high, this low profile, 30 inch diameter Flo-Thru screen separator fits neatly between the rotary valve of a bulk bag discharger and a pneumatic conveyor inlet.

Stuart Sundblom, of Stuart Systems Co., Olathe, KS, a representative for pneumatic conveyor and screen separator equipment, devised a space saving solution incorporating a Kason Flo-Thru low profile, 30 inch diameter, circular vibratory screener which fit neatly between the discharger outlet and conveyor inlet. He also scaled-down a dust collector to occupy the remaining floor space.

Whereas conventional, circular, vibratory screeners are equipped with one imbalanced-weight gyratory motor positioned beneath the screening chamber, the Flo-Thru design is configured with two of the motors mounted on opposing exterior sidewalls of the unit, reducing overall height to 24 inches, an 8 inch savings for the 30 inch diameter model selected.

Side-mounting of eccentric weight motors also enables the bottom outlet to be located directly below the top inlet, allowing material entering the unit to fall vertically through the screen and discharge at high rates.

The 30-42 lb/cu. ft. bulk density regrind is now discharged into the compact screener which, equipped with a 22 mesh screen, ejects particles exceeding 0.038 inch in size through a side-mounted outlet, and gravity discharges sized material into the pneumatic conveyor inlet at rates to 3600 lb/hr.

The circular vibratory separator employs gyratory motors with adjustable, Compact screen separators imbalanced weights to impart multi-plane inertial vibration to the entire spring-mounted screening chamber, causing oversize particles to vibrate across the screen surface in controlled pathways to the screen periphery where they are discharged. Undersized particles pass rapidly through the screen onto a funneled bottom surface and through the center discharge outlet.

By contrast, a rectangular shaker screen of equivalent capacity requires significantly greater screen surface area since material flows in a straight-only path, crossing each course of screen at one point, only one time.

Taber's Products, founded in 1936, is a contract packager of a variety of bulk and liquid products, including paints and sealants for tire retread products sold by International Marketing Inc., marketer of the regrind product for tire balancing.

"Without the Flo-Thru vibratory circular screen separator, we probably would not have switched to pneumatic conveying," says Byron Taber, operations manager. He also anticipates packaging a more coarsely ground plastic for tire balancing in the future, necessitating changeovers to and from a larger mesh screen, saying, "The screens are easy to bolt on and remove in about 20 minutes which became a convincing feature in our specification of this equipment."