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Show 5.9.7 ATOMIZERS (INJECTORS) The method of injection of the liquid into the burner or incinerator furnace is one of the most important features of a well designed system. The main purpose of injecting the liquid as a spray are: 1. To break up the liquid into fine droplets. 2. To place the liquid droplets in a specific zone with a specific pattern with sufficient penetration and kinetic energy. 3. To control the rate of flow of the liquid discharged to the nozzle. (6) Organic and aqueous liquids go through three phases before actual oxidation is initiated. (Hydrocarbons ignite at temperatures as low as 450°F and as high as 1200°F.) They are heated, vaporized and superheated to ignition temperature. (Fig.2) It is important, therefore, that liquid droplets be exposed to high temperature surroundings so heat transfer by radiation and convection will occur. Also, it is very important that there is intimate contact with air (oxygen) so as high temperature levels are reached, oxidation will begin to occur. If the droplet diameter is large, fewer droplets will be produced and total surface available for transfer of heat is rninimized. An example is shown below: Ratio of number of droplets N 125yu _ ., fl N 30()u J Ratio of surface area A 125u n ^n^a ATOQE = °-1736 For an equal flow rate of liquids, the total surface available for heat transfer is as follows: 13.8 x 0.1736 = 2.396 Atl25 N125 A125 At = total surface area x <JS At300 N300 A300 N = No. of droplets = 13.8 x 0.1736 ^ 5 m 2.3 96 t300 |