High Pressure Fog & Spray
The photographs on the right, represent a variety of applications where Applied Conveyor Technology has provided High Pressure Fog or Spray systems. Locations such as clam gates, the top of open hoppers, rail dump stations, building openings and conveyor feed points are all excellent candidates for spray or fog suppression.Nozzle types and spacing as noted will vary and be specified per type of product and application location.
HIGH PRESSURE FOG or SPRAY refers to water droplets that have been generated using water at extreme pressures and highly engineered nozzles and equipment. Water, when pressurized and forced through precision nozzles can be atomized into small droplets less than 10 micron in diameter (less than 10% of the diameter of a human hair). Fog/Spray droplets evaporate directly into dry air from the surface of the droplet. By creating a smaller droplet size, the ratio of Volume vs. Surface area is greatly increased. Since dust suppression only takes place from the surface of the water droplet, the greater this ratio the more effective the water. In addition, the 10 micron sized water droplets are much more readily attracted to the fugitive PM10 and sub PM10 particles. The electrical attraction between dust particles and fog droplets allows the two to combine based on the Van de Vaal’s Forces. The resulting amalgam (being heavier than air) drops toward the ground for collection or inclusion with the main product.
The use of Fog and/or Spray will depend upon the parameters of the application. Fog should only be used in confined or contained areas since it is small and light. The slightest wind will dissipate it and render it less effective. Spray, on the other hand can with stand air movement whether generated, induced, or displaced and is effective in such areas as truck dumps, open hoppers, open head chutes, crushers and train dumps.
Nozzles are made of brass and stainless steel, with an engineered rifled impeller that “pulverizes” the water as it passes through. Finally the water exits through a 0.008” (0.20mm) orifice to create the 10 micron fog cloud and slightly larger orifices for spray screen. The percentage of moisture by weight added will usually be less than 1%. Water is treated, filtered, and compressed up to pressures exceeding 1,000 psi (70 Bar) in an engineered pumping unit. Special switches and safety units ensure that the pump is protected at all times from low and high water pressure situations. At this point suitable surfactants can be added to the fog lines to further reduce the “surface tension” of the water, making the fog even more effective. The high pressure water is fed through flexible or rigid lines through to the nozzle lines located at the point source emission of the fog/spray. Nozzles are spaced on the lines according to the intensity of the dust generation and natural air velocities.
HIGH PRESSURE EQUIPMENT
The equipment exhibited on the right are examples of Applied Conveyor Technology’s self-contained High Pressure Fog/Spray units. Equipment can be provided enclosed or exposed, fabricated in Stainless or Carbon Steel and be supplied with a wide variety of finish coatings. ACT systems are custom engineered and designed per specific applications.