Fine Dry Powder Handling

Author
(not verified)
Posted in: , on 17. Feb. 2004 - 09:08

Fine Dry Powder Handling Lifts its Efficiency with Better Pneumatic Actuation

by Chris Webb, Engineering Manager

Air Springs Supply Pty Ltd., Australia

In any industry, developing a more efficient process can lead to superiority over the competition.

This is what pneumatic engineers in Australia and internationally are seeking to achieve by improving pneumatic actuation and isolation of materials handling equipment including vibrating equipment and tilting containers, such as those of powder handling innovator Semi-Bulk Systems.

“Because fewer moving parts and reduced complexity usually equate to less wear and more reliability, we are encouraging processors to consider air spring actuators and isolators in new applications. These air springs – called Airstrokes and Airmounts – are particularly appropriate in situations requiring rapid cycling, high reliability and minimal susceptibility to wear in grimy industrial situations,” says Australian pneumatics engineer Mr. Chris Webb, of Air Springs Supply Pty Ltd.

Working with the world’s biggest producer of air springs, Firestone, Mr Webb and Firestone engineers internationally are developing expanding uses for the flexible-wall, bellows-type Airstroke and Airmount air cylinders. These air springs are, in essence, tough, fabric reinforced rubber balloons of different shapes to perform different tasks. They can be small enough to fit in the palm of a hand, or more than a metre across and capable of producing 40,000 kg of force.

Firestone’s engineering team recently examined the Airstroke application of Semi-Bulk Systems Inc, a US company that manufactures state-of-the-art equipment and containers for unloading, batching and processing bulk quantities of fine-dry powders, such as paint pigments, clays used as thickeners, carbon black used in copy machines and other talc-like powders.

Semi-Bulk Systems’ process for unloading vinyl bags of powder of 400-3800kg has typically been simply to discharge the product through a hole in the bottom of the bag. The problem with that, says Mr. Webb, is that the product comes out in big slugs, rather than evenly and smoothly.

“Semi-Bulk’s solution to this issue has been to blow air through the powder to break it up and make it fluffy, so it can discharge through a 100mm (four-inch) hole at the bottom of the container.”

The container allows for controlling flow of material through its use of a support stand with a hinged deck beneath which an Airmount isolator is inflated at about 1 bar (12psi). The stand supports the container at its corners with hooks, allowing gravity to dispense the powder through the hole in the container floor.

“Semi-Bulk puts the container on the deck and lets it begin to empty through gravity. When the powder gets down to about 25 per cent left in the container, the pressure in the Airmount is greater than the weight of the container, causing the hinged deck to rise. This tilts the container so the remaining powder will flow evenly toward the discharge port,” says Mr. Webb.

Semi-Bulk uses two types of Airmounts:

• Double convoluted Model 26s for smaller bags. These Airmounts are of 250mm maximum diameter and about 1200kg load capacity at 5.5 bar and maximum stroke of 145mm (80psi and 5.7in respectively – although Semi-Bulk employs pressures and load capacities well inside these ranges)

• Triple convoluted Model 38s for larger bags. These large Airmounts (which already have years in use in Australia in heavy industrial plant) have a maximum diameter of approx 950mm and load capacity of 40,000kg at 5.5 bar and maximum stroke of 350mm (80psi and 13.8 in – again, Semi-Bulk operates them well within these ranges)

Semi-Bulk’s process also includes a smaller Model 16 Airmount that inflates when the hinged deck tilts, activating an air piston vibrator that vibrates against the container base and helps dispense the powder further.

Semi-Bulk Systems’ Product Development Manager Mr. Ben Wanner says his organisation has been using Airmounts for more than 10 years.

“They replaced air cylinders - the key factor for us was that we could use one Airmount to replace two cylinders. Plus, the air cylinders always required some lubrication or maintenance, which the Airmounts don’t. And the Airmounts are hidden up under the deck, so there’s nothing exposed to clean.”

Mr. Webb says a major advantage of the Airstrokes and Airmounts is that they don't use the guides and seals found in traditional pneumatic cylinders. This difference is the key to many of their benefits in rigorous production environments, ranging from metal stamping, vibrating screen and conveyor applications through to labeling, sealing and packaging tasks. Airmounts are used in Australia to isolate equipment as diverse as compressors, computers, generators and refrigeration and air-conditioning equipment.

For more information, please visit:

http://www.airsprings.com.au

https://edir.bulk-online.com/profile...lk-systems.htm

Photo:

Further view of the Airmount and entire support stand at Semi-Bulk Systems. This stand allows the flow of powder to be carefully regulated.

Attachments

airspringsaus_news17.02.04 (GIF)

Write the first Reply