In this paper, using the detergents spray-drying as an example, spray-drying technique is discussed, the simulation of which is performed in computer spreadsheet program (Lotus 1-2-3 rel. 3.1). Energy and mass balance have been derived for the conventional drying process (single inlet air passage trough spray-dryer), and the cost-cutting model is proposed by means of recirculation of part of the exhaust air. From the calculation presented it is obvious that it is possible to recirculate from zero to 70% of the total exhaust air, whereas from the thermodynamic point of view, the inlet air keeps its drying capacity. The model proposed contributes to the essential simplification of the drying process description. It is possible to apply it for the existing drying process analyze and redesign as well as for the new plants design.