Drying of suspensions and solutions on inert particle surface in mechanically spouted bed dryer

Abstract

To eliminate some disadvantages of the conventional spouted bed dryers the mechanically spouted bed (MSB) system was developed. This dryer type is convenient to use inert particles providing an increased surface area for drying of materials of high-moisture content and heat sensitive materials. On three different drying tasks are demonstrated the experimental optimization of process parameters to obtain products of demanded quality. The main object was at drying of AlO(OH) suspension to preserve the particle size under 2.5 μm and to obtain product with a moisture content of about 0.05 kg/kg (d.b.). For this reason a very thin particle coating and intensive abrasion had to be assured. At drying of tomato concentrates the thermoplasticity makes the process very difficult. To jump over the deliquescent and sticky state developed at the critical temperature–moisture content values a very short drying time (8–10 s) must be provided. The third task was to form powder-like product from bovine serum albumin (BSA) solution having very low solid content (2–4%). The selected process parameters given in this paper resulted in a mean particle size of less than 20 μm while the soluble preserved protein content was higher than 90%.