Jan 012013
 
Click image to enlarge.

When you have multiple bins in series with a recycled asphalt pavement (RAP) belt scale system, how do you adjust your blending controls or bin speed to accommodate for recycled asphalt shingle (RAS) product clogs or clumps?

The folks at Clarence Richard Company, Minneapolis, designed the EZ-Flo feeder scale to weigh the light-loaded product—RAS—as well as heavy loaded product—RAP—and to retrofit into existing bins while wiring into the blending computer usually with no hardware/software changes. With the bin feeder scale for RAS/RAP in place, the blending control can then make changes to the feeder speed based on actual weight instead of assumed volumetric weight.

Here’s How it Works:

The gravity fed feeder scale fits in the cramped area usually between two RAP bin feeders and the collector belt.
As the plant operator calls for material, the RAS (or RAP) falls from the RAS/RAP belt feeder impacting the feeder scale before falling to the collector belt.

Click image to enlarge.

Click image to enlarge.

As the RAS impacts the suspended plate of the scale, the force of this material flow forces the plate against a single load cell rod. The load cell measures this force and converts it into a rate signal, known as the rate of material flow, which a rate indicator reads in the control house.

The rate reading in tons per hour indicates how quickly material is passing through the RAS flow scale and produces a signal used for blending materials.

At the control house, the RAS feeder tach signal used by most blending controls is replaced by the frequency rate signal. This information compensates for the changes in RAS density or flow (bin bridging) and can easily allow the operator to be notified when the bin runs empty.

The bin is now being calibrated with a scale that reads flow rates much lower than the typical RAP belt scale.

For more information about the EZ-Flo bin feeder scale for RAS/RAP, contact Clarence Richard Company at clarence@clarencerichard.com or visit www.ez-flo.us.

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