Romanko S. The process of sulphuric acid solution concentration by evaporation into indifferent gas flow at external heat injection

The thesis presents the results of an experimental investigation of the influence of indifferent gas, which is injected into the free space above acid solution or bubbled through it, and operating conditions of the process on the intensity of the solution concentration process. A method of determining the acid solution evaporation rate has been suggested, and its dependences on the solution composition that confirm the presence of the critical acid concentration in the solution, at which the acid (H2SO4 monohydrate) starts evaporating along with water, have been determined experimentally. It has been shown that, within the range of solution concentration values before and after the critical concentration, the dependences of the evaporation rate on the solution composition are of a different nature. The study of concentration heat transfer and mass transfer has been carried out, the heat flux values at heat exchange between liquid and gaseous phases have been determined, and the conditions, at which the heat-exchange flow changes its direction, have been ascertained. By means of modelling the aforementioned process, the regularities of the solution composition change over time for a batch process and the dependences on the initial solution flow value for a continuous process at different concentration conditions have been determined. The suggestions have been made concerning the equipment needed for this process on the basis of a standard capacitive apparatus and a film apparatus, as well as the methods of calculating the batch and continuous concentration processes in the capacitive concentrator.