Spray solid-cone

Hydraulic (Pressure) Nozzles Manufacturers data such as shown by Fig. 14-88 are available for most nozzles for the air-water system. In Fig. 14-88, note the much coarser solid-cone spray. The coarseness results from the less uniform discharge. 

Solid-cone spray atomizers usually generate relatively coarse droplets. In addition, the droplets in the center of the spray cone are larger than those in the periphery. In contrast, hollow-cone spray atomizers produce finer droplets, and the radial liquid distribution is also preferred for many industrial applications, particularly for combustion applications. However, in a simplex atomizer, the liquid flow rate varies as the square root of the injection pressure. To double the flow rate, a fourfold increase in the injection pressure is... 

At the beginning of the process, after loading the product, the lower part of the chamber is filled with water of adequate chemical and bacteriological quality. The air contained in the chamber is not removed. A sanitary-type pump circulates the filling water through a heat exchanger (of the removable-plate or other sanitary type) that is indirectly heated in countercurrent with plant steam. The water is then sprayed onto the load by a sparger located in the upper part of the chamber and equipped with a system of solid-cone spray nozzles. Uniform water redistribution in the lower layers of the load is ensured by suitable perforated racks that support the product. Sometimes additional water spray bars are located on both sides of the chamber. 

The liquid reflux distributors above each packed zone are often arrays of solid-cone sprays preferably the nozzles should be V4 iiich or larger in orifice, free passage, and pipe sizes. The spray liquid needs to be screened at all times. The sprays are not as good distributors as the drip-pan type, but they are economical and contribute to heat transfer without adding substantial pressure drop. The nozzles should be designed to operate at a flow rate that gives a good spray pattern without excessively small droplet sizes. 

Several types of injectors have been investigated for delivering the fuel. These include pressure-swirl atomizers, air-assisted atomizers, and single-hole and multihole injectors delivering solid-cone sprays. Injection pressures vary depending on the type of injector, but they are generally less than 20 MPa. In the case of solid-cone sprays, drop SMDs vary from about 50 pm at about 2 MPa to 15 pm at about 10 MPa. Air-assisted injectors typically deliver smaller diameters. Pressure-swirl atomizers can generate drops that are about 20 pm at about 5 MPa. 

FIG. 14-87 Charactersitic spray nozzles, a) Whirl-chamber hollow cone, (h ) Solid cone, (c) Oval-orifice fan. (d) Deflector jet. (e) Impinging jet. (/) Bypass, (g) Poppet, (h) Two-flnid. ( ) Vaned rotating wheel. 

These results show that droplet vaporization must be different between the three flames. Droplet and fuel vapor transport must be significantly different for these flames and must affect combustion efficiency. The solid-cone nature of the spray flame was found to be preserved irrespective of the atomization gas. 

The droplet number density presented in Fig. 16.4 indicates the solid-cone nature of the spray except in the immediate vicinity downstream of the nozzle exit. On the spray centerline at 2 = 10 mm, steam provides a lower number density as compared to the two air cases. This is due to the expansion of the spray jet at a relatively lower Reynolds number with steam and rapid vaporization of smaller sized droplets. At increased radial positions and 2 = 10 mm, a peak in the number density corresponds to the spray cone boundary. This peak shifts radially outwards with an increase in axial distance due to the expansion of the spray cone. Similar phenomena are observed for the normal and preheated air cases except that droplet number density for the preheated air case is much higher on the spray central axis (at r = 0). This is attributed to the effect of preheated air on atomization (i.e., larger mean droplet size and smaller number density with normal air as compared to that for heated atomization... 

The spray pattern is also important. A solid cone pattern mixes less well than a hollow cone, sheet, or multiple jet patterns. Drops that enter along the edge of the spray pattern nearest the exit have less time to heat up and evaporate. Drops that enter along the edges of the spray pattern nearest the walls may not fully evaporate before hitting the walls, resulting in erosion and corrosion of the brick. 

Core-insert cone nozzles prodnce either a solid or hollow cone spray pattern. They operate at moderate pressnres and give a finely atomized spray. They shonld not be used for wettable powders because of small passages which tend to clog and wear rapidly due to abrasion. 

Disc-core nozzles produce a cone-shaped spray pattern which may be hollow or solid. The spray angle depends on the combination of disc and core used and also, to some extent, on the pressure. Discs made of very hard materials resist abrasion well, so these nozzles are recommended for spraying wet-table powders at high pressures. 

Pneumatic nozzles prevail, but the spray pattern is somewhat different than found in a fluidized bed. In air suspension systems, the spray is usually a comparatively narrow, but solid cone of droplets. In a nozzle configured for perforated pan coating equipment, the initial spray pattern is also a solid cone. However, this pattern is flattened to an elliptical. shape by the u.se of. secondary atomizing air, delivered from openings adjacent to and angled slightly toward the primary atomized droplet stream (Fig. 10). In most nozzles, this secondary air is adjusted and controlled independently. The nozzle is... 

The ICP-OES nebulizers can aspirate up to 1-2% dissolved solids (a dry wine has 2-4% total extract). Some nebulizers, such as the Babington and cone-spray nebulizers, were studied to handle as much as 15-20% dissolved solids, but are not ideally conceived for use in ICP-MS. Pneumatic nebulizers are commonly used to generate an aerosol of samples with dissolved components below 0.2%. Pneumatic devices are made from glass or different kinds of polymers and use argon as nebulizer gas. The characteristics of some of the most popular pneumatic nebulizers are detailed below. 

Sprays also may be used for liquid distribution. When more than one nozzle is needed, overlapping (or underlapping) of spray patterns is inevitable. Care must be taken to select a foil cone spray nozzle that does not have too fine a mean drop size (to prevent entrainment of liquid by the rising vapor) and which Has a good pattern of spray over the needed cross section. Nozzles are available for handling liquids containing suspended solids, and thus spray distribution is a possible solution lo tha need to distribute a dirty liquid. 

Examples of the spray pattern produced by the Delavan nozzles (a) hollow, (b) solid cone, and (c) all purpose. 

Fig.21.tmprical correlation of solid cone nozzle spray tower performance tests. 

Solid-cone nozzle Flat-spray nozzle Slot nozzle Perforated die (sprinkler)... 

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