Process equipment spray dryers

If the product in no way adheres to the dryer parts and simple cyclone collectors are sufficient for gas-sohds separation, batch operation of a spray dryer may be considered. Otherwise, the time and costs for cleaning the large equipment parts make them rarely economical for other than continuous processing of a single material. 

In Europe process equipment such as spray dryers, flnid-bed dryers, and mills are available in shock-resistant designs for pressures up to 10 barg (145 psig). 

Conical ends are used to facilitate the smooth flow and removal of solids from process equipment such as, hoppers, spray-dryers and crystallisers. 

Likewise, the capital investment for the spray dryer MgO process is approximately 7 percent lower than that for the conventional MgO scrubbing process ( 279/kW vs. 299/kW). The conventional MgO scrubbing process has more equipment, and hence larger investment costs, particularly in the areas of chloride purge, slurry drying, and slurry processing equipment which are not needed in the spray dryer-based system. 

In the comparison of the annual revenue requirements for the spray dryer MgO process with those for the conventional MgO process, it is apparent that both the first year and the levelized annual revenue requirements are 40 lower for the spray dryer MgO process ( 28.8M vs. 40.4M for first year). The most significant difference between the processes is the energy cost, in particular, the fuel oil charges. The spray dryer MgO process uses expensive fuel oil only to operate the waste disposal equipment while the conventional MgO process uses fuel oil, not only for the waste disposal equipment (which is a relatively minor amount) but also to fire the calciner and... 

Typical control measures used in pharmaceutical industry to reduce VOCs (including odors) are condensation, absorption (spray towers, venturi scrubbers, packed columns, and plate columns), adsorption (using activated carbon beds), thermal destruction (flares, boilers and process heaters, thermal incinerators, and catalytic incinerators), and vapor containment. Water- or brine-cooled condensers are the most common control devices, with carbon adsorbers in occasional use. Where the main objective is not solvent reuse but is the control of an odorons or toxic vapor, scrubbers or incinerators are used [86]. Typical spray dryer systems equipped with thermal and catalytic incinerators are shown in Figure 53.7. 

In both of the processes just described, a crystallizer produces a solid and, following a solid-liquid phase separation, a dryer removes the moisture. In some cases, all three of these operations can be carried out in a single piece of equipment, a spray dryer or a drum dryer, but at the expense of increased utility cost because all of the solvent is evaporated. Such dryers are used extensively to produce dried milk and detergents. For these products, spray dryers are particularly desirable, because the drying process produces porous particles that are readily dissolved in water. Spray dryers can also handle slurries and pastes. 

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