Bairds Malts are major producers of malts for brewing and distilling, with production facilities in Scotland, Lincolnshire and Essex. Pulsar Process Measurement have supplied non-contacting ultrasonic level measurement to Bairds' Arbroath maltings for an awkward dust level measurement, replacing a RADAR system that was failing to provide reliable results.
Malt processing generates wheat and barley dust or fines as a by-product, and this dust is collected and stored in a large silo before being mixed with other components, such as molasses, and extruded as pellets of animal feed.
Animal feed production is crucial to the entire process because, while the malting plant is in production, dust is produced and has to be continuously stored or processed. If production of animal feed pellets stops there is a risk that the dust storage could overfill and either overflow or stop the main process. At the same time, it is important that there is always enough fine material to make up a batch in the animal feed mixer. Molasses accidentally fed to an empty mixer will cause a substantial production delay while it is cleaned out.
Therefore, it is very important that the level of fines material in the silo that feeds the animal feed process is well understood and properly controlled. The objective is to maintain the level within a fairly narrow band to provide a consistent gravity feed to the mixer, and the level measurement device controls auger feed from two upstream storage bins that take dust directly from the main process.
Bairds Malts approached Pulsar Process Measurement when a previously installed guided wave radar device proved unreliable, producing 'false' low level alarms that led to the entire plant being shut down while the 'problem' was cleared. Pulsar supplied an Ultra 5 ultrasonic controller for the 5 metre high silo, coupled with a foam face dB15 transducer. The dB15 has a 15m range, and the foam face increases the amount of acoustic energy transferred through the air. The extra power ensures that the system had no difficulty with the high atmospheric dust levels in the silo. The Ultra 5 controller provides a display of percentage fill and five on-board relays, which are used to control the two auger feeders from the upstream storage silos and to provide an emergency low-level alarm. Pulsar's DATEM echo processing algorithm digitally processes the echo signal to provide rock-solid, reliable performance.
The equipment was commissioned by Pulsar, using an aiming kit to direct the transducer as close to perpendicular to the natural angle of repose of the material for the best possible echo.
Since installation early in 2012, the Pulsar equipment has operated without missing a beat and without giving a single false alarm, As Colin Tait, plant engineer, put it, 'it is a thing of beauty'.