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Address:
Air Environmental Systems LTD
4 Bramley Road Market Deeping
Peterborough
Lincolnshire
PE6 8JG
Phone:
01778 349696
Fax:
01778 349697
Email:
Steve Coomes
Managing Director
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The Technology of Spraying for Dust Suppression
Airborne spray technologies can be highly efficient and cost effective solution in controlling dust, it is a simple concept, yet its implementation entails significant complexity and several factors must be considered before optimum spray system solutions can be identified as variations in performance can compromise effectiveness and create new problems. The following information details available options and explains how to ensure the optimum spray system performance.
DUST SUPPRESSION BASICS
Dust is generated by wind erosion as well as by moving, crushing, grinding or milling materials to a finer size. It consists of solid particles larger than 1 micron (µm) in mean diameter. Particles less than 10 µm are the most dangerous, as these can enter the respiratory system and causebreathing difficulties.
Among basic methods to achieve dust control, wet dust-suppression spray systems increase humidity/moisture content in the product stream, helping to minimise dust overall and prevent it from becoming airborne. Moisture can be added to the material when it is stationary or moving. Such systems use nozzles that produce drops in the 100 to 250 µm range to create a fine drizzle effect.
By contrast, airborne dust-capture spray systems produce very fine water drops to collide with dust particles in the air, forming agglomerates of dust and water too heavy to remain airborne. Water droplets that are too large will not collide with the finest, most hazardous dust particles and droplets that are too small evaporate quickly and release the captured dust. Nozzles that produce a fine mist consisting of droplets in the 20 to 100 µm range or a fine drizzle consisting of droplets in the 100 to 250 µm range are most effective. Collision is most likely to occur when the drops and dust particles are similar in size.
In addition to droplet size, effective spray system performance and dust suppression depend upon such spray characteristics as drop distribution, drop velocity, spray pattern and spray pressure.
Spraying dust with liquid adds weight to the particulate matter and prevents it from becoming airborne or settles it quickly, if already airborne. Adding moisture to dust and materials during processing also helps minimise the amount of dust produced downstream.
Dust suppression will continue to be a critical issue for aggregate plants and storage areas because of intensified environmental regulation and social scrutiny. Using atomised water spray to reduce dust is advantageous because water is not a hazardous material and is usually in plentiful supply at plant locations. The fogging dust-suppression system is relatively inexpensive compared with more elaborate dust collection methods. The atomisedwater suppression system requires few modifications to applications and can normally be positioned out of the way of other equipment. Air Environmental Systems offers a bespoke solution to you Dust Suppression requirements, please give us a call and we will be glad to discuss any issues you may have and advise on the best way forward.