Spray drying variations

A variation of the n on regen erabi e absorption is the spray dry process. Time slurry is sprayed through an atomizing nozzle into a tower where it countercurtendy contacts the flue gas. The sulfur dioxide is absorbed and water in the slurry evaporated as calcium sulfite-sulfate collects as a powder at the bottom of the tower. The process requires less capital investment, but is less efficient than regular scmbbing operations. 

The physical properties of spray-dried materials are subject to considerable variation, depending on the direction of flow of the inlet gas and its temperature, the degree and uniformity of atomization, the solids content of the feed, the temperature of the feed, and the degree of aeration of the feed. The properties of the product usually of greatest interest are (1) particle size, (2) bulk density, and (3) dustiness. The particle size is a function of atomizer-operating conditions and also of the solids content, liquid viscosity, liquid density, and feed rate. In general, particle size increases with solids content, viscosity, density, and feed rate. 

The range of application of shear cell testing methodology is seen in Tables 2-6. Table 3 relates the flow properties of mixtures of spray-dried lactose and bolted lactose. These mixtures, in combination with the excipients tested, cover a broad range of flow. Tables 4 and 5, for example, show lot to lot variations in the flow properties of several materials, and Table 6 shows the variation in flow properties of bolted starch, sucrose, and phenacetin at different relative humidities (RH). Figure 8 presents the yield loci of sucrose at four different consolidation loads. Also shown in the figure are the shear indices determined at each consolidation load. 

Often overlooked in the evaluation of the effects of diet upon mineral availability is the role that food processing plays in the formation of or breaking of ligand-metal complexes. Several individual or unit processing steps are needed to produce a soy concentrate, a bread or a spray-dried egg white. Some or all steps may have a bearing upon final mineral bioavailability. Soy concentrate from company A is not produced in precisely the same manner as from company B. In fact, lot to lot variation for the same product may be quite variable, particularly in mineral content. 

Instead of an electronic furnace, an r.f. inductively coupled plasma (ICP) is also used to generate high temperatures. This method is named a spray lCP technique and has been applied for a wide variety of oxides.Another variation of the spray pyrolysis is the spray- drying method that uses slurry or sol of metal... 

Vromans, H. Lerk, C.F. de Biggelaar, H. Van. Bosch, H. Studies on tableting properties of lactose. VII. The effect of variations in primary particle size and percentage of amorphous lactose in spray-dried lactose products. Int. J. Pharm. 1987, 35, 29-37. 

Sorbitol can exist in four crystalline forms. Guyot-Hermann, Leblanc, and Draguet-Brugmans compared 11 commercially available varieties of sorbitol, and found three of these four forms to be present. y-Sorbitol was found to be the most useful as a tablet diluent. The method of manufacture has also been shown to affect tabletting properties, differences being attributed to variations in particle shape and surface properties. Spray-dried varieties of sorbitol are available as direct compression diluents which are claimed to have overcome problems associated with the different crystalline forms. ... 

Due to the very large surface area created by the atomization of the feed, rapid evaporation occurs from the surface of each particle or droplet in the spray. The magnitude of the surface area can be illustrated by a simple calculation. Atomization of 1 L of water into a uniform spray of 100-jxm droplets results in approximately 1.9x10 individual particles with a combined surface area of 60 m. A realistic spray with variation of the droplet size may have a substantially higher number of droplets and a somewhat higher surface area. The dry... 

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