Dryer designs

Another important class of dryer is the fluidized-bed dryers. Some designs combine spray and fluidized-bed dryers. Choice between dryers is usually based on practicalities such as the materials handling characteristics, product decomposition, product physical form (e.g., if a porous granular material is required), etc. Also, dryer efficiency can be used to compare the performance of different dryer designs. This is usually defined as follows -. 

Evolving Dryer Design to Improve Heat Integration... 

Dryers are different in characteristic from distillation columns and evaporators in that the heat is added and rejected over a large range of temperature. Changes to dryer design can be directed by the plus/minus principle. 

Based on dryer cost alone, indirect-heat dryers are more expensive to build and install than direct-heat dryers designed for the same duty. As environmental concerns and resulting restrictions on process emissions increase, however, indirect-heat dryers are more attractive because they employ purge gas only to remove vapor and not to transport heat as well. Dust and vapor recovery systems for indirect-heat dryers are smaller and less cosdy to supply heat for drying, gas throughput in direct-heat dryers is 3—10 kg/kg of water evaporated indirect-heat dryers require only 1—1.5 kg/kg of vapor removed. System costs vary directly with size, so whereas more money may be spent for the dryer, much more is saved in recovery costs. Wet scmbbers ate employed for dust recovery on indirect-heat dryers because dryer exit gas usually is close to saturation. Where dry systems are employed, all external surfaces must be insulated and traced to prevent vapor condensation inside. 

Design Methods for Spray Dryers Design variables must be... 

Unless employed by one of the specialist equipment manufacturers, the chemical engineer is not normally involved in the detailed design of proprietary equipment. His job will be to select and specify the equipment needed for a particular duty consulting with the vendors to ensure that the equipment supplied is suitable. He may be involved with the vendor s designers in modifying standard equipment for particular applications for example, a standard tunnel dryer designed to handle particulate solids may be adapted to dry synthetic fibres. 

Consequently, we consider that the industrial scale technological management of microwave assisted chemical reaction is no compatible with batch reactors coupled with multimode applicators. Some typical processes with a systematic decrease of the dielectric losses of the concerned reactant, such as filtration and drying of mineral or pharmaceutical powders are compatible with multimode applicators. To our knowledge, the only industrial batch microwave device is the microwave variant of the Turbosphere ( all in one solution mixer/granulator/dryer designed by Moritz... 

Forewarmed milk or skim milk is concentrated by vacuum evaporation to contain 40-60% total milk solids. The degree of concentration is determined to meet dryer design requirements and is used to control the particle size, density, dispersibility, and solubility of the powder. 

Calculations for dryer design. Trans. Am. Inst. Chem. Eng., 1 184-202-Guest, Paul G. 

Drying equipment may be classified in several ways. The two most useful classifications are based on (1) the method of transferring heat to the wet solids or (2) the handling characteristics and physical properties of the wet material. The first method of classification reveals differences in dryer design and operation, while the second method is... 

The procedure outlines in Steps 1 through 5 employing Eq. (1) through (15) will result in satisfactory fluid bed dryer design. The first step is to assume T2 and then other quantities can be evaluated in order. A computer program using Fortran, MATHCAD, TK SOLVER, or other such programs may be used to solve this problem. Partial results for the first interval are ... 

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