Changes in the liquid solutions humidity during drying

The drying kinetics of wet materials is usually depicted as graphic dependences of the drying curve in the coordinates "moisture content - drying time" and the drying rate curve in the coordinates "drying speed - moisture content". At a low concentration (4-10 %) of solids in the solution, the moisture content at the initial moment of time is very large and can be more than 10,000 %, and at the end of the drying process it becomes equal to the equilibrium moisture content, which practically merges with the abscissa axis on the drying curve. The purpose of the study is to identify the regularities of the graphic dependence "solution moisture - drying time" for liquid solutions and high-moisture materials. It is proposed to supplement the study of the kinetics of drying liquid solutions with a solids concentration of less than 10 % with a graphical dependence "solution moisture - drying time". The following mixtures were considered as objects of study: brewer's grain filtrate, brewer's grain, water - oil, water - sugar, water - protein (protein is mixed with distilled water heated to 100 °C). The temperature of the drying agent is 60 °C. Experimental data are presented on the kinetics of drying a liquid solution of distilled water - denatured protein obtained by keeping a homogeneous solution of distilled water - native protein in a water bath at 110 °C followed by drying at a temperature of 60 °C. The morphology of structure formation of dried solutions with native and denatured proteins is considered. The native protein dissolved in distilled water, after drying, is a continuous thin cloudy film, and the denatured protein film is transparent, indented, uneven in thickness and with clearly defined irregularities. It has been established that the nature of the dependence "solution moisture - drying time" at a low concentration of solids is steep, with an increase in concentration it becomes flat, characteristic of most wet materials. The removal of free moisture corresponds to two sections on this curve.