Determination of the Rational Number of Turns of a Screw Mixer With an Active Return Channel

Abstract

The conducted studies have shown that a promising design and technological scheme of the mixer is a low-speed screw mixer of periodic action, the loading and unloading parts of which are connected by an active return channel having areas of interpenetration of feed mixture components.It is established that the cycle time consists of the time of passage of the components of the mixture through the sections of the screw winding, tangential blades and in the return channel under the action of an additional screw. The time spent by the mixture on the screw section and in the return channel is determined by the length of each section, the design parameters of the winding, the angle of installation of the housing to the horizon and the rotation frequency of the working body. When determining the time spent on the interpenetration site of the components of the mixture, it is necessary to take into account the filling factor of the return channel and the physico-mechanical properties of the components of the mixture.The duration of loading and unloading of the mixer is determined from the condition of the axial velocity of movement of the feed mixture components in each of the sections and corresponds to the cycle time.The residence time of the mixture at each of the sites is determined taking into account the design parameters and the rotation speed of each working body. The optimal ratio between the diameters of the auger and the additional auger from the condition of the maximum volumetric capacity of the mixer is revealed. Expressions are obtained for determining the supply of working bodies at each of the sections from the condition of continuity of the flow. Modeling of the volumetric feed allowed us to estimate the effect on the volumetric flow of the mixer depending on the ratio of the pitch of the screw turn to its diameter, the number of screw turns.