For the layout of gas cooling systems as they are used for example in evaporation coolers or ducts in cement plants the droplet diameter of the injected cooling water is important. The smaller the droplet size the shorter the evaporating distance.
If very fine droplets are required for a complete evaporation of the injected cooling water in small evaporation coolers or ducts often Laval nozzles are chosen.
The nozzles of the new VJ II-3 series can offer considerable savings potential for the required atomizing air volume, as shown in the following example.
At a cement plant gas should be cooled down from 375°C to 320°C inside an duct with 2,2m diameter. At present 4 lances each with one piece Laval nozzle 180.641.1Y.81.00.0 are installed. The max. operation point with together 36 l/min injection of water needs total an amount of 170 m³/h STA atomizing air at 4,8 barg to get a full evaporation.
If the 4 pieces Laval nozzle 180.641.11Y.81.00.0 would be replaced by 4 pieces VJ II-3 nozzle 120.444.1Y.AL.00.0 the atomizing air volume required for complete evaporation of the injected water at the maximum operating point after the same evaporation distance can be reduced to a total amount of 56 m³/h at 3,9 barg. This corresponds to a reduction of the required atomizing air quantity by more than 60%, which means a considerable reduction in energy costs.
The required water pressure of the VJ II-3 120.444.1Y.AL.00.0 is approx. 0,9 bar higher at this operating point compared to the L0 nozzle 180.641.1Y.81.00.0.