The technology for continuous thermal vacuum drying of dispersed materials, which has been developed beginning from 2006, is the result of a series of research and design development works at SPE RESST (see Fig.1) in the field of energy-efficiency and sustainable technologies of drying of dispersed raw materials, industrial and agricultural products [4–6,20, 21].
Fig.1. SPE RESST laboratory apparatus used to optimize the process parameters of thermal vacuum drying of agricultural production
Application of vacuum technologies permits to decrease significantly the temperature and the energy capacity of the process with maximum conservation of native properties of dried products as for their goodness and structure properties at microlevel. It is proved by the results of many experimental investigations with application of precision nuclear physics and electron microscopy (see, for example, Fig.2).
|Fig. 2. Results of electron microscopic (in zoom ×12000) investigation of the ultrathin structure of apricot cells and organules before (a) and after (b) vacuum drying at optimum temperature of 50°Ñ.|
In particular, within the framework of the program YaMRT-2010*, using the γ-activation analysis of microelement content in the dried pressed grape skins [6,20] it has been established that the processed different-sort grape waste demonstrate a selectivity in the accumulation of heavy-metal and actinoide contamination components that is very important for the development of new phytotechnologies of soil decontamination and deactivation.
An actual national economic problem in Ukraine is the drying of large mass-flows of wet dispersed materials – grain, saw dust, shavings, chalk, sand, sandy gravel, silica gel etc. To solve this problem it is necessary to have energy-efficient industrial plants and technologies of continuous drying. In 2006 the specialists of SPE RESST offered the design of a high-yielding vacuum drying apparatus for continuous drying of loose and slurred materials and for concentration of liquid products (like fruit juice and milk). The distinctive feature of this apparatus is a tubular construction element combining the functions of a vacuum volume and an electric heater, and the dispersed material is interruptedly pumped through the heating element by the water-packed ring pump. In the commercial variant the estimated yield of the apparatus is 1 tone (of grain) per hour. The drying apparatus is compact, metal-consuming, ease for manufacturing, maintenance and transportation and can be used as a stationary or movable unit in the agriculture and in the food-, pharmaceutical-, woodworking- and chemical industries of Ukraine. SPE RESST has upgraded the experimental bench of the apparatus design in order to test the developed technologies of continuous drying of dispersed materials.
*Government program of fundamental and applied investigations on the problems of using nuclear materials and radiation technologies in the field of industry development