Level Control in a Dusty Environment

Posted in: , on 21. Feb. 2012 - 01:21


I am working on a project where we are looking for a level control system for a dusty environment.

Essentially this is part of a grinding loop where product is reduced to 5 to 20 micron in size. The ground product is separated using an air classifier and is pneumatically conveyed to a bag type dust collector. The product is dropped off the bags (reverse pulse jet) into a ribbon type re-blender. After blending it then goes to the next stage of processing. The dust collector sits directly on top of the re-blender.

At the moment there is an ultrasonic probe that "hangs" by its power cable in the dust collector. The bags are mounted horizontally and the probe hangs in the space from the end of the bags to the collector wall.

In between each product run, everything is taken apart and thoroughly cleaned with pressure hoses and sprays. As a result, the probe gets dragged out of the way and ends up failing either because it is hit with the pressure spray, or because it has to be "hung" out of the way, damaging the cable.

We are now trying to find a different way of measuring the level of product in the re-blender. Looking at the various types around, it is the fragility of the probes that is the issue. The vibrating blade types are likely to have the blades damaged during washdown. The same goes for paddle type, and even here the paddle has to be mounted in a corner. There are radar units, however it is the proximity of other object might be an issue.

The last that will cause the most disruption is to have the dust collector separate from the re-blender, and mount the re-blender on load cells.

Anyone have any thoughts on possible alternatives?


[I]Ian A. White, MIEAust. CPEng. RPEQ WAI Engineering [URL="http://www.wai.com.au"]www.wai.com.au[/URL][/I]
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