Drying

Abstract

Drying is an operation in which volatile liquids are separated from solids, slurries, and solutions to yield solid products. Drying mechanisms and processes, including psychometry, heat‐ and mass‐transfer principles, and a description of liquid and vapor flow encountered during drying are discussed. In freeze drying (lyophilization), wet material is cooled to freeze the liquid and vaporization occurs by sublimation. Industrial dryers may be broadly classified according to the method of heat transfer as being either direct‐heat or indirect‐heat dryers. The types of dryers employed in the chemical industry, which may also be classified as batch or continuous, are described. Conventional, radiant, dielectric, and microwave heat sources are discussed as are emission control and energy usage of the various dryer types.

Stability of slot‐rectangular spouted beds with multiple slots

“…[1] While the ability to scale up conventional spouted bed in cylindrical columns is limited, [2] the slot-rectangular spouted bed, consisting of a column of rectangular cross-section with a thin rectangular slot symmetrically located at the bottom, [3] were proposed to facilitate scale-up. Originally called 'two-dimensional spouted beds', this configuration was renamed 'slot-rectangular spouted bed' by Dogan et al [4] and Freitas et al [5] because of significant three-dimensional effects which arise as the column thickness increases.…”

“…Units of greater thickness-to-width ratio can only be found in laboratory cold models. As a possible solution, Mujumdar [3] suggested a bank of parallel narrow chambers with common walls between adjacent beds. Kalwar et al [12] also advocated scaling-up by adding units in any orthogonal direction such that the laboratory scale apparatus can be considered as a single module in a series of similar modules, possibly sharing walls between adjacent units.…”