We can solve this problem with sound. Here is an example of how we have already done so;

Date: June 9th 2009
Location: PET Processors (UK), Dumfries, Scotland
Product: PAS 420 Audiosonic Acoustic Cleaner
Principle: Primasonics International Limited (UK)

Problem: Silo Discharge Cross Contamination, Silo bridging

These various products are produced in pelleted form and stored within an eight tonne silo. Unfortunately Silo Discharge Cross Contamination was occurring within the discharge cone section which resulted not only in loss of product but also loss of production due to having to manually clean the silo out between different product types.

The most troublesome material was polyester pellets with a particle size of between 2 and 3mm and a moisture content of 100ppm. The material formed soft clumps which caused Silo bridging over the outlet.

Primasonics Director of Technology visited site to meet with the originator of the enquiry, Stuart Eckersley, Plant Engineer and discuss the benefits that would be achieved by installing a Primasonics Acoustic Cleaner just above the silo outlet to prevent Silo bridging.

It would prevent any material from building up in this hopper area, thus preventing Silo Discharge Cross Contamination, without causing any structural damage to the silo wall as can be the case with either vibrators or mechanical hammers.

The Solution

Primasonics supplied an Acoustic Cleaner Model PAS-420 complete with External Mounting Tube and other accessories. A small hole was cut on the side of the hopper discharge and the mounting tube welded in place. The PAS-420 Acoustic Cleaner was bolted to the flanged end of the mounting tube and the accessory items put in place.

The Acoustic Cleaner was powered via a solenoid/timer by compressed nitrogen to avoid oxygen contaminating the product which activated the titanium diaphragm to create the correct sound frequency. The timer was set to sound the Acoustic Cleaner for a few seconds only at periodic intervals but only during either filling or discharging from the silo.

The Result

The positive effect of sounding the Acoustic Cleaner was immediate with total emptying of the silo on every occasion. Silo bridging caused by material build up was eliminated and therefore also was the serious problem of Silo Discharge Cross Contamination. Stuart Eckersley, Plant Engineer is now a very happy man and the savings in terms of both downtime and product losses have more than paid for the Primasonics Acoustic Cleaner.