Experimental study of convective dryer with centrifugal fluidized bed

Nowadays, the units with a fluidized bed hold a special place among all heat-mass transfer plants currently used in industry. First of all, it is due to the highly developed surface of interaction between the fluidizing agent (air) and dispersed materials in such units, their low hydraulic resistance, relatively simple design and small sizes. At the same time, the units with a centrifugal fluidized bed, which is formed in an annular channel of the working chamber when a fluidizing agent is added under the fixed angle, are of particular interest. Currently, a limited number of experimental and theoretical studies of hydrodynamics and heat-mass transfer in a fluidized bed are known. Besides, these studies were carried out mainly in respect to regenerative heat exchangers and absorbers. In this regard, such studies in respect to the devices for other purposes, such as dryers, seem to be relevant. The results of these studies are the scientific backgrpund for development of an engineering calculation methodology of such units and their design. The study has been carried out based on an experimental plant using means for measuring temperature, relative air humidity, differential pressure, air velocity, and moisture content of solids. A TPM 148 PID controller has been used as a secondary device. Experimental data have been recorded in MasterSCADA SCADA system. Data processing has been carried out using interpolation by cubic splines. The article describes in detail an experimental plant that allows carrying out a full factor experiment to study the hydrodynamic and thermal parameters of a convective dryer with a centrifugal fluidized bed. The article presents the results of a preliminary series of experiments in which silica gel is used as a dispersed material. As a result of visual observations over the dispersed material in the working chamber, the values of the minimum and maximum speed of the drying agent have been determined. The grafic relationship of the hydraulic resistance of the working chamber and the height of the material layer are obtained depending on the speed of the drying agent and the mass of the material, as well as the temperature and moisture content of the material and the drying agent depending on the drying time. The results obtained make it possible to determine the design and operational parameters of the centrifugal fluidized bed drying plant and select a fan to supply the drying agent.