Atomized spraying

Fig. 6. Intake manifold system with a water-atomizing spray nozzle distributing to four individual cylinders. See text.

Hollow Sprays. Most atomizers that impart swid to the Hquid tend to produce a cone-shaped hoUow spray. Although swid atomizers can produce varying degrees of hoUowness in the spray pattern, they aU seem to exhibit similar spray dynamic features. For example, detailed measurements made with simplex, duplex, dual-orifice, and pure airblast atomizers show similar dynamic stmctures in radial distributions of mean droplet diameter, velocity, and Hquid volume flux. Extensive studies have been made (30,31) on the spray dynamics associated with pressure swid atomizers. Based on these studies, some common features were observed. Test results obtained from a pressure swid atomizer spray could be used to iUustrate typical dynamic stmctures in hoUow sprays. The measurements were made using a phase Doppler spray analyzer. 

Table 2. Summary of Atomizer Sprays for Specific Applications...

Fig. 17. Open-cycle, cocurrent, disk atomizer spray dryer.

Spray Angle A shift to a smaller-angle nozzle gives slightly larger drops for a given type of nozzle because of the reduced tendency of the sheet to thin. Dietrich [Pi oc. 1st Jnt. Conf. Liq. Atomization Spray Systems, Tokyo, (1978)] shows the following ... 

Plate Towers Plate (tray) towers are countercurrent gas-atomized spray scrubbers using one or more plates for gas-liquid contacting. They are essentially the same as, if not identical to, the devices used for gas absorption and are frequently employed in apphcations in which gases are to be absorbed simultaneously with the removal of dust. Except possibly in cases in which condensation effects are involved, countercurrent operation is not significantly beneficial in dust collection. 

This type of technology is a part of the group of air pollution controls collectively referred to as "wet scrubbers." Venturi scrubbers are also known as venturi jet scrubbers, gas-atomizing spray scrubbers, and ejector-venturi scrubbers. The technology is based on the removal of air pollutants by inertial and diffusional interception. 

Aerosols are also a form of a mist characterized by highly respirable, minute liquid particles. They can be formed by atomizing, spraying, or mixing, or by violent chemical reactions, evolution of gas from a liquid, or escape of a dissolved gas when pressure is released. 

Atomizing spray wheels rotate at speeds to 20,000 rpm with peripheral speeds of 250-600 ft/sec. With nozzles, the length to diameter ratio of the dryer is 4-5 with spray wheels, the ratio is 0.5-1.0. For the final design, the experts say, pilot tests in a unit of 2 m dia should be made. 

American physicist Robert A. Millikan and his student Harvey Fletcher designed an experiment to determine the charge on the electron. As shown in Figure 2-14. the apparatus was a chamber containing two electrical plates. An atomizer sprayed a mist of oil droplets into the chamber, where the droplets drifted through a hole in the top plate. A telescope allowed the experimenters to measure how fast the droplets moved downward under the force of gravity. The mass of each droplet could then be calculated from its rate of downward motion. 

Air-Atomized Spray Airless Spray Pressure-Atomized Electrostatic Spray... 

Evaporation of Atomized Droplets. The prediction of the time to totally evaporate a liquid droplet in an atomized spray is very difficult due to the complex thermal and concentration gradients present in the vicinity of the nozzle. Despite this complexity, it will be beneficial to study what happens to a single droplet of liquid when it is surrounded by a quiescent gas stream. This phenomena has been studied extensively because the time to evaporate a liquid drop has important consequences in a number of different applications e.g., spray drying, fuel injection, and coating. 

Depending on the scrubber design, the scrubbing liquid is sprayed into the gas stream before the gas encounters the Venturi throat, or in the throat, or upwards against the gas flow in the throat. The scrubbing liquid is then atomized into small droplets by the turbulence in the throat, and droplet-particle interaction is increased. Some designs use supplemental hydraulically or pneumatically atomized sprays to augment... 

Atomizer sprays, 23 198t Atomizing-spray burners, 23 659 Atoms... 

Disinfection processes, as advanced wastewater treatment, 25 909-910 Disjoining pressure, 12 6-7 Disk agglomeration, 19 8 Disk atomizer spray dryer, 9 127 Disk bowl centrifuge, theory of performance, 5 518 Disk centrifuges, 18 144... 

Plain-orifice atomizers are widely used for injecting liquids into a flow stream of air or gas. The injection may occur in a co-flow, a contra-flow, or a cross-flow stream. The best known application of plain-orifice atomizers is perhaps diesel injectors. This type of injectors is designed to provide a pulsed or intermittent supply of fuel to the combustion zone for each power stroke of the piston. As the air in the combustion zone is compressed by the piston to a high pressure, a very high pressure (83-103 MPa) is required to allow the fuel to penetrate into the combustion zone and disintegrate into a well-atomized spray. 

Self-Induced Spray Scrubbers Self-induced spray scrubbers form a category of gas-atomized spray scrubbers in which a tube or a... 

Gupta, A. K., C. Presser, J. T. Hodges, and C. T. Avedisian. 1996. Role of combustion on droplet transport in pressure-atomized spray flames. J. Propulsion Power 12(3) 543-53. 

Liquid atomization is an important unit operation that is employed in a variety of processes. They include fuel atomization, spray drying, metal powder production, coating of surfaces by spraying, etc. 

Pan and cascade burners are generally more limited in flexibility and are useful only where low sulfur dioxide concentrations are desired. Gases from sulfur burners also contain small amounts of sulfur trioxide, hence the moisture content of the air used can be important in achieving a corrosion-free operation. Continuous operation at temperatures above the condensation point of the product gases is advisable where exposure to steel (qv) surfaces is involved. Pressure atomizing-spray burners, which are particularly suitable when high capacities are needed, are offered by the designers of sulfuric acid plants. 

In order then to determine what influences flavor retention during drying, one must focus attention on the very early stages of dehydration. In fact, it has been shown that the major fraction of total volatiles lost during nozzle-atomized spray drying occurs within ten centimeters of the pressure nozzle (17, 33, 35). 

The heart of a furnace black production plant is the furnace in which the carbon black is formed. The feedstock is injected, usually as an atomized spray, into a high-temperature and high-energy density zone, which is achieved by burning a fuel (natural gas or oil) with air. The oxygen, which is in excess with respect to the fuel, is not sufficient for the complete combustion of the feedstock, which, therefore is for the most part pyrolyzed to form carbon black at temperatures of 1200-1900 °C. 

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