Flame and spark detectors defeat dust explosions
15 Jan 2000
At its plant in Sponden, Derby, Courtaulds Chemicals manufactures methyl cellulose from wood pulp. The end product, known as Celacol, has a variety of uses and is made in a range of powder grades. But powder processing can be prone to dust explosions, a fact that Courtaulds has taken note of by installing Trolex TX6221 flame and spark sensors at strategic points in the plant's ducting that conveys the products from processing to storage areas.
In the process, the wood pulp raw material is shredded in an attritor and heated. The resultant powders are conveyed along short ducting runs, before being sieved and loaded into IBCs. Oversized particles are fed back into a second in-line grinder. Although spontaneous combustion of the fine particles is unlikely, there is a possibility of larger particles lodging in the ductwork where, with the process heat involved, they could start to smoulder and cause a serious incident. The Trolex sensors are designed to shut the process down before this happens.
The five IS-certified sensors employed on the plant detect low frequency infrared radiation at 1-2.8 micron wavelengths, with a response time of 0.8 seconds.
