Nozzles designs

The stability of liquid jets and the influence of nozzle design have been assessed (23). A major task of a nozzle is the efficient conversion of potential energy to kinetic energy. This is best achieved by a sudden, smooth contraction of the flow area from the supply line to 

The best angle of convergence seems to be rmcertain. The aspect ratio of the nozzle is highly dependent on the initial jet velocity profile and the subsequent jet surface shape. Rounding and polishing of the internal surfaces of the nozzle seem to be of importance for optimal performance (23). 

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Equipment Operation Spray nozzles suffer from caking on the outside and clogging on the inside. When the nozzle is below the bed surface, fast capture of the liquid drops by bed particles, as well as scouring of the nozzle by particles, prevents caking. Blockages inside the nozzle are also common, particularly for slurries. The nozzle design shoiild be as simple as possible and provision for in situ cleaning or easy removal is essential. 

Product diameter is small and bulk density is low in most cases, except prilling. Feed hquids must be pumpable and capable of atomization or dispersion. Attrition is usually high, requiring fines recycle or recoveiy. Given the importance of the droplet-size distribution, nozzle design and an understanding of the fluid mechanics of drop formation are critical. In addition, heat and mass-transfer rates during... 

Recent developments in nozzle design have led to drastic reductions... 

If it becomes necessary to increase the stack-gas exit velocity to avoid downwash, it may be necessary to remodel the stack exit. A venturi-nozzle design has been found to be the most effective. This design also keeps pressure losses to a minimum. 

MTC recommends a nozzle design similar to that shown in Figure 5-8, separating the pressure plate adjusting ring functions. This provides the following advantages ... 

Traver.se number temperature factor), (a) The peak gas temperature minus mean gas temperature divided by mean temperature rise in nozzle design, (b) The differenee between the highest and the average radial temperature. 

The Spray tree is used to distribute water over the wet deck in counterflow cooling towers. It can consist of a single header fitted with spray nozzles or, it can utilize spray branches with nozzles for wider coverage. Spray nozzle designers seek minimal pressure requirements and uniform coverage over wide flow ranges. 

Applicability/Limitations Liquid injection incineration can be applied to all pumpable organic wastes including wastes with high moisture content. Care must be taken in matching waste (especially viscosity and solids content) to specific nozzle design. Particle size is a relevant consideration so that the wastes do not clog the nozzle. Emission control systems will probably be required for wastes with ash content above 0.5 percent (particulate control) or for halogenated wastes (acid gas scrubbers). 

Changes to a distribution system can be of assistance in minor improvements. Nozzle designs are under constant review but it is in the context of pack changes that amendments are important. 

Air distributors. Improvements in the metallurgy, refractory lining of the outside branches, and better air nozzle design, combined with reducing L/D of the branch piping, have reduced thermal stresses, particularly during start-ups and upset conditions. 

For superheated steam, the sample points should be designed and installed to permit correct isokinetic sampling. A modified multiport nozzle design ensures that the velocity of the steam entering the sample nozzle is the same as the velocity of steam in the header. The design incorporates a small, high-quality water delivery tube, used to inject water and remove superheat before sample extraction. 

Multiannular nozzle design, 16 8, 9 MultiBatchDS software, 26 1040 Multibladed disk turbines, 15 692-693 Multiblock copolymers, applications of, 24 715-716 MULTICASE, 6 19... 

Seed stage medium, 77 28 Seed trains, in fermentation, 7 7 42 Segmented-arc nozzle design, 76 8 Segmented elastomeric polyurethane fibers, 25 476-477... 

Tube collectors, 26 702 Tube-cooled converter, in methanol synthesis, 26 309 Tube furnaces, 12 739 Tube-in-orifice jet nozzle design,... 

Sprays of fine droplets can be generated by first mixing a liquid with liquefied gas under pressure and then expanding the mixture through a nozzle. This technique, referred to ssliquefied gas atomization, has been used in many applications such as commercial aerosol cans. The mean droplet size generated with this technique is very small. In very few systematic studies, the measured droplet size distribution was found rather widely spread.[881 It is not clear, however, how the liquid amount, pressure, and nozzle design affect the mean droplet size and size distribution. 

Factors influencing jet breakup may include (a) flow rates, velocities and turbulence of liquid jet and co-flowing gas, (b) nozzle design features, (c) physical properties and thermodynamic states of both liquid and gas, (d) transverse gas flow,[239] (e) dynamic change of surface tension, 1151[2401 (f) swirlj241 242 (g) vaporization and gas compressibility,[243] (h) shock waves,[244] etc. 

Various correlations for mean droplet sizes generated by air-assist atomizers are given in Table 4.6. In these correlations, mA is the mass flow rate of air, h is the height of air annulus, tf0 is the initial film thickness defined as tj ) = dQw/dan, d0 is the outer diameter of pressure nozzle, dan is the diameter of annular gas nozzle, w is the slot width of pressure nozzle, C is a constant related to nozzle design, UA is the velocity of air, and MMDC is the modified mean droplet diameter for the conditions of droplet coalescence. Distinguishing air-assist and air-blast atomizers is often difficult. Moreover, many... 

For prefilming type of atomizers, minimum droplet sizes are obtained with nozzle designs that spread liquid into thinnest sheet before subjecting its both sides to air-blast action 86] and provide maximum contact between liquid and air. 468 From experimental data obtained over a wide range of process conditions and material properties, it was found 469 that the effect of liquid viscosity on the mean droplet size is independent of that of surface tension and air velocity. Therefore, the mean droplet size can be expressed as a sum of two terms one dominated by surface tension, air velocity and air density, and the other by liquid viscosity, as suggested by Lefebvre 4691... 

For the delivery of atomization gas, different types of nozzles have been employed, such as straight, converging, and converging-diverging nozzles. Two major types of atomizers, i.e., free-fall and close-coupled atomizers, have been used, in which gas flows may be subsonic, sonic, or supersonic, depending on process parameters and gas nozzle designs. In sonic or supersonic flows, the mass flow rate of atomization gas can be calculated with the following equation based on the compressible fluid dynamics ... 

Korobochka and Pavlenko 705 proposed a simple model and nozzle design for the determination of exact droplet size distribution generated by an air-assist nozzle. The approach enables the direct measurements of droplet size and allows generation of a very narrow range of droplet size distribution. 

Thrust restraiuts are required at the pump if an expansion joint is installed on the discharge nozzle. Design review of the proposed installation and piping by the vendor is recommended. 

The nozzle design and characteristics of the water spray pattern to be produced. 

Special vortex nozzle designs which deliver lower flows using a large opening have been used to reduce plugging problems. Also, viscosity-sensitive nozzles, where flow is increased as viscosity is increased, are used to control variation in solids concentrations. 

The type of spray system is usually characterized by one of four nozzle designs (Fig. 8) (29) ... 

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