Technical Details & Downloads
Dust control systems are an important factor in meeting both environmental and health and safety requirements, while also helping and protecting employees and reducing site emissions. We offer complete solutions for the control of dust in all material handling processes, ranging from our dry fog dust suppression systems to rain gun and sprinkler systems.
Our dry fog dust suppression systems control airborne dust without wetting the product while adding very little moisture (usually less than 0.1% moisture addition). Our systems are fully installed and integrated into all processes and control dust without the need for expensive extraction systems or chemical additives.
Dust suppression theory and application:
Dry Fog fugitive dust suppression works like a combination of a wet scrubber and a fabric filter. The generated ultra-fine fogging blanket acts like a fabric filter in that a dust particle cannot pass through it without colliding with a droplet. Since the droplet consists of water, the dust particle does become somewhat wet as in a true flooded scrubber. This phenomenon can be called agglomeration. Solving fugitive dust emission problems using ultra-fine water droplet atomisation begins with the theory of agglomeration. Agglomeration can be defined as the gathering of mass into a larger mass, or cluster.
Agglomeration probability is greatly increased between bodies of similar size. The agglomeration of these bodies produces a large enough mass to cause settling. For example, a dust particle of 5 microns will continue to follow the air stream around a water droplet of 200 microns, therefore, avoiding collision. With the dust particle and a water droplet of similar size, the air stream is not as great and collision occurs, causing agglomeration.
The diagram below shows the aerodynamics of what can happen when the water droplets are larger than the dust particle.
Diagram illustrates the importance of droplet size for particle agglomeration. Airflow around the large water droplet (left) prevents the dust from contacting the droplet. However, the dust particle easily impacts the small droplet (right) triggering agglomeration.
Fog suppression is one method to optimise the application of water to dusty materials. These systems use special ultrasonic nozzles to produce extremely small water droplets (10 microns or less) in a dispersed mist. These droplets mix and agglomerate with dust particles of similar size, with the resulting larger combined particles falling back to the material body.
Dry Fog Dust Suppression Systems control virtually all types of less than 5 micron breathable as well as larger size fugitive dust up to 600 microns. Control is accomplished through agglomeration of ultrasonically produced water droplets equal or close to the size of the dust particles. These include silica sand, dried clay, dry sand, limestone, aggregate, road stone, phosphate, coal, quartz, fibreglass and many others. The Dry Fog system suppresses visible emissions from primary and secondary crushing, screening, transfer and loading-unloading facilities such as hoppers, feeders, bins, docks, silos, terminals and vehicles.
The sonicom atomising nozzle along with a compressed air supply and simple on/off controls will suppress respirable dust as small as 0.1 to 3 microns as well as larger size particles. The initial cost, operation and maintenance of a Dry Fog System is much lower than a ventilation type control system. In contrast to the use of large ducts and related equipment, the sonicom system operates with smaller diameter tubing on as little as 5% of the total energy of conventional systems. Dry Fog systems can be installed for as little as 40% of the installation cost of a conventional bag filter type system.
Basic research in the development of the sonicom Dry Fog Dust Suppression System showed that if a sufficient number of water droplets of approximately the same size as the dust particles could be produced, the possibility of collision between the two would be extremely high. It was also determined that if the droplet exceeded the size of the dust particle, there was little probability of impact and the desired precipitation. Instead, the dust particle would move around the droplet.
The sonicom nozzle assembly is ideally suited for generating a dense fog of ultra fine droplets to envelop and bring down the dust particles at their source. By controlling air pressure, atomisation quality can be varied from course – 200 microns – to an ultra-fine fog of 1 to 10 microns. When the nozzle is complemented with our special water valve assembly, the unit becomes a highly efficient self cleaning atomiser.
The heavy duty stainless steel water valve is controlled by the same compressed air supply used to activate the nozzle. A simple on/off signal is required to activate the system and when the signal is removed, the water valve self cleans the nozzle every time by blowing excess water away, significantly reducing lime, salts and chalk build-up.