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Modeling of particulate or thin-layer drying of materials is necessary to understand the fundamental transport mechanism and a prerequisite to successfully simulate or scale up the whole process for optimization or control of the operating conditions. Simple models with a reasonable physical meaning are effective for engineering purposes. Thin-layer drying of green peas was carried out in a fluidized bed with a newly developed slotted gas distributor. Based on the reaction engineering approach, a drying model of green peas was well established, in which relative activation energy (ΔEv/ΔEv,b) was correlated with reduced moisture content (X − Xb) at a drying air temperature of 80°C. The drying kinetics of green peas was discussed in terms of activation energy. In addition, activation energy based on a simplified material surface temperature profile was recalculated to evaluate the temperature sensitivity to the model establishment.

During drying, hydrodynamics of fluidized beds can vary due to moisture evaporation. It is of practical importance to quantify the fluidized bed hydrodynamics by analysis of pressure fluctuations, especially when drying cohesive materials. In this study, spent liquor from a fermentation process for the production of yeast was mixed with corn bran at different mass ratios, and used as the fluidizing material of various stickiness levels. Local bed pressure fluctuations and the dryer exhaust air temperature as well as relative humidity were monitored over the course of drying. The pressure fluctuation data were analyzed using statistical methods. The bed hydrodynamic behavior was interpreted in terms of the time-averaged bed-pressure drop and its standard deviation. The transition from channeling to uniform fluidization occurs when both the average pressure drop and the standard deviation vary little with time. Also, the average values of the bed-pressure drop within short periods in reference to the ideal ...