STORAGE
F
BELT MISALIGNMENT
I
- A dangerous and common cause of dust explosions
by Vaughn Entwistle, Features Editor, Milling and Grain n the June edition of Milling and Grain we carried a special feature on the dangers of dust explosions and explored several strategies for reducing the risk of these serious incidents. So, it was with great interest that at the recent VIV Europe 2018. I discovered a relatively simple and cost-effective piece of technology for potentially preventing dust explosions on conveyors and bucket elevators. Because bucket elevators account for 30-40 percent of all grain handling dust explosions, it’s easy to consider them as ‘dangerous’ installations with a very real potential for the risk of explosion. One of the major culprits in these explosions is belt misalignment. A misaligned belt, rubbing against another part of the conveyer, can quickly generate a great deal of heat and friction, and might even shoot out sparks. When heat/sparks come together with a cloud of highly flammable grain dust, it often results in a powerful explosion. However, research shows that these explosions and the resulting damage can easily be limited with various belt misalignment monitoring systems for horizontal and vertical transport. To alert conveyor/bucket elevator users to belt misalignment, Dutch company Muller Beltex created Rub-Block. A typical RubBlock system employs four temperature sensors—two mounted at either end of a belt system. Unlike competing sytems, Rub-Block
80 | August 2018 - Milling and Grain
detects belt misalignment based on raised temperatures generated by friction. Rub-Block uses a PT100 temperature sensor to report the misalignment of a conveyor belt, elevator belt or HI-roller. The RB200DN can be used for elevators from 12 metres height. The advantage of the Rub-Block is that it emits a continuous standby signal to the PLC. If such a signal is absent, the reason for this must be investigated and, if required, the PT100 sensor must be