INCREASING THE EFFICIENCY OF SEPARATING LIQUID SYSTEMS ON THE BASIS OF IMPROVING ENERGY CHARACTERISTICS IN ROTORS OF FILTERING CENTRIFUGES OF VARIOUS DESIGNS

Abstract

The relevance of the research is caused by the need to provide more efficient economy, improve reliability and durability, efficiency and productivity of centrifuges. It is required to obtain and study their energy characteristics, especially those associated with energy costs to overcome various harmful resistances. Obtaining the energy characteristics of centrifuges is also necessary to create new drives, since the belt drive currently used in industrial centrifuge drives has significant drawbacks, some of which are unacceptable. Purpose: based on the results of experimental studies, propose a new mathematical model for a separated system movement in the rotors of filter centrifuges with centrifugal and screw unloading of sediment in thin-layer filtration of suspensions with a medium-grained solid phase and a volume concentration of less than 60 %. Objects. The processes in the rotors of filtering centrifuges with centrifugal and screw unloading of sludge during thin-layer filtration of suspensions with a medium-grained solid phase are studied. Experimentally, in the rotors of the centrifuges under consideration, it is possible to distinguish two zones – the pressure filtration zone and the centrifugal pressing zone. If the filtration mode is violated, the suspension from the pressure filtration zone can fall into the centrifugal pressing zone. In places of suspension breakthroughs, as well as in the pressure filtration zone, the sediment layer is washed off. Methods. According to the developed mathematical model, the rotor is divided into two zones along the generatrix. There is no sediment in zone I, it is washed away by the suspension flow and thrown into zone II, where sediment is accumulated with a volumetric moisture content of about 40–50 %. Sediment in zone II is accumulated until the stresses from the tangential component of the centrifugal force become equal to the internal shear stresses in the sediment. After that, the sediment begins to move along the rotor, gradually freeing itself from moisture. To determine the length of the pressure filtration zone, a differential equation was compiled that describes the flow of liquid along the rotor (in the form of a thin film) with its simultaneous filtration through a sieve. The sediment movement in zone II is considered. In the first approximation to the rheological model, the sediment is taken as a non-Newtonian liquid. Results. The mathematical model of the movement of the separated system in the conical rotor proposed on the basis of the conducted analytical and experimental studies makes it possible to determine the length of the pressure filtration zone and calculate the process parameters that ensure the presence of a zone and sediment in the rotor, as well as determine the duration of the sediment in the rotor, knowing which, one can according to known formulas, calculate the moisture content of the resulting sediment.

Keywords

• tubular
• filtering centrifuges
• mechanism of movement of the divided system
• productivity
• rotor speed