Spray nozzle particle size

Rupture disk, 455 Safety relief valves, 454, 467, 481 Specifications, centrifugal pumps, 209 Spray nozzle particle size, 225 Standards and Codes, 31, 32, 33 Static electricity, 536 Static mixing, 332 Applications, 336 Calculations, 337, 338 Materials of construction, 337 Principles of operation, 335 Type of equipment 334-338... 

Spray characteristics of pressure nozzles depend on the pressure and nozzle-orifice size. Pressure affects not only the spray characteristics but also the capacity. If it is desired to reduce the amount of liquid sprayed by lowering the pressure, then the spray may become coarser. To correct this, a smaller orifice would be inserted, which might then require a higher pressure to produce the desired capacity, and a spray that would be finer than desired might result. Multiple nozzles tend to overcome this inflexible charac teristic of pressure atomization, although several nozzles on a diyer complicate the chamber design and air-flow pattern and risk collision of particles, resulting in nonuniformity of spray and particle size. 

Nozzle blockages. Occasionally nozzles get blocked, therefore several spare nozzles are usually kept available during operation. With a suitable filter size, good operating, and cleanout practices, these occurrences can be minimized. However, most towers have inspection windows that allow operators to monitor atomization during operation. Alternatively, constant monitoring of the spray dried particle size can indicate upstream problems before their impact can get out of control. 

In drying solutions or slurries of solutions, the location of the feed-injection nozzle (spray nozzle) has a great effecl on the size of particle formed in the bed. Also of importance are the operating temperature, relative humidity of the off gas, and gas velocity. Particle growth can occur as agglomeration or as an onion sldnuing. ... 

Approximate Particle Sizes From Liquid Full Cone Spray Nozzles ... 

In order to tailor the physical properties of nano-particles, wet granulation was conducted. Hydroxypropylecellulose (HPC-L) 5% aqueous solution was sprayed onto nano-sized Ti02 particles through a binary nozzle. Fluidization air velocity was set at approximately 1.5 times as large as the minimum fluidization air velocity. 

Impinging jets, which consist of a cylindrical chamber with two spray nozzles that enter from opposite sides of the chamber, provide small particles with narrow size distribution. The solution oi the material is fed through one nozzle and the crystallization agent through the second nozzle. Finasteride has been cry.stallized in this way a solution of the material in acetic acid plus some water was fed from one nozzle and water from the other the average crystal size was 10 to 15 pm. 

Ultrasonic sprays produced via horns are also finding use in spray drying installations where there are clear advantages in producing minimal particle velocity with a controlled particle size through a non-clogging nozzle. 

Water spray—Water discharged from nozzles, specially designed to give a certain pattern, particle size, velocity, and density at a given application rate. 

Scratches can also be caused by particles by another means. Since in CMP the slurry (particles included) stays on the polish pad, and the polish pad material is removed by the end effector, the end product of this complicated slurry-pad material reaction is a kind of substance with unknown characteristics and sizes. These substances can be the cause of the scratches. Figure 18 shows such substances collected by an end effector [16]. If the end effector is not properly cleaned, these particles can become hardened and cause severe scratches. To prevent this, a high-pressure water spray nozzle or a rotating brush can be used. 

The bubble column and spray tower depend on nozzles to disperse the drop or bubble phase and thus provide the high area and small particle size necessary for a high rate. Drop and bubble coalescence are therefore problems except in dilute systems because coalescence reduces the surface area. An option is to use an impeller, which continuously redisperses the drop or bubble phase. For gases this is called a sparger reactor, which might look as shown in Figure 12-16. 

To maintain the same particle size the triple-headed nozzle could spray three times the pilot unit spray rate at a 2.5 atomization air pressure. However, this could result in a longer process time. Another approach to maintain the similar droplet size is to maintain the mass balance of spray rate and the atomization pressure. Thus, by increasing the atomization pressure to 5 bar, the spray rate was increased to 800g/min, keeping the same droplet size and, hence, obtaining granulation with the desired characteristics. 

CA 59, 13763(1963) (Powdered AN expls prepd by mixing ingredients, such as AN 60, NaN03 12, KC1 4.5, NaCl 3.5, DNN 7, flour 1 urea 3%, followed by heating to 120° with agitation. The resulting melt is then sprayed thru a nozzle into a dry, cool flue to crystallize as a powder of desirable particle size)... 

With the methods discussed in Chapter 6.5. we are able to produce small polymer particles from solutions of polymers in compressed gases [52,53], First results indicate that, depending on the process conditions and the nozzle design, a wide variety of spherical particles, small fibrils, or longer fibres can be obtained. Sometimes the particle-size distribution obtained is very uniform, in other cases, a wide variety of sizes is obtained. In some cases, the monomer was used as solvent for the equivalent polymer. The particles, fibrils, etc., obtained may be used for direct spray-coating of surfaces but they also offer new opportunities as raw materials in their own right. New products are underway that are based on such technologies. 

Wetzel (75) atomized both molten wax and a molten alloy in a Venturi nozzle and established empirical equations for expressing the magnitudes of the effects of operating conditions on the particle-size distribution of the spray. An advantage of molten alloy is that a permanent record of the spray is obtained and large numbers of particles may be sized by physical methods. 

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