Drying Machines with Combined Hydrodynamic Regimes

The article is devoted to the study of multistage dryers with vertical sectioning of the working space. The factors of influence of the design of the shelf contact and the consumption of the drying agent on the mode of movement of monodisperse and polydisperse material are analyzed. The achievement of the required hydrodynamic regime (at a constant consumption of the drying agent) was ensured by changing the length of the shelf contact, the angle of its inclination to the horizon, and the degree of perforation (free area of cross-section). The features of changing the mode of granular material movement at various stages of the gravitational shelf dryer are shown. A technique for the optimization calculation of a gravitational shelf dryer is proposed. As an objective function, the minimum residence time of the dispersed material in the dryer is taken, at which the required amount of moisture is removed. Variants of the designs of the stages of a gravitational shelf dryer are shown and the features of the movement of dispersed material on the steps are described. The results obtained can be used as the basis for the engineering design of gravitational shelf dryers.

CONFORMITIES TO LAW OF FORMING LAYER FOR POLYDISPERSE PELLET CHARGE ON SINTER BELT

Motion of pellet charge on the loading tray on a sinter belt is accompanied not only by the change of its grain-size composition, but by segregation processes, id est. by the redistribution of charge of different size particles for the most part friable material. The result of this process is formation of local discontinuity with pre-dominance of content for particles of certain factions. The traditional method for analysis of work for loading tray on the basis of factious classification does not allow to educe and analyze appearing heterogeneity in the most part friable material. It results in errors at the calculation for action of the system of the automated control by sintering process and ignoring of notational of the use of segregation of particles of friable material for optimization of technological process. The use of balance method enables to specify and spread understanding of mechanism of processes which take place during motion of pellet charge in relation to the loading tray, and also to form theoretical pre-conditions for the choice of the rational modes of operations of agglomeration separation of sintering plant. It is set that at monotonous increase of angle of slope for loading tray the segregation phenomena increase in a pellet charge, and after achievement of the defined value – go down, id est. have extreme character. Mentioned features of forming of layer for polydisperse material in the conditions of inconstancy of mechanical properties of its separate factions it is possible to take into account at the use of balance of grain-size composition of charge, loaded on a sinter belt, and charge, being on it, when conditional middle diameters of particles of their components must be equal. On the basis of the set conformities to law of forming of friable of structure of layer the method of authentication of grain-size compositions of pellet charge mixture is in theory reasonable in every its horizon taking into account a segregation during loading.

PROBABILITY AND STATISTICAL APPROACH TO THE DESCRIPTION OF AERODYNAMIC INTERACTION OF COLLECTIVE OF INCIDENT PARTICLES WITH AIR

In the mountain industry a considerable part of technological processes are followed by loadings of bulk in various capacities and the bunker. When loading bunkers of silage type self-dumping carts the problem of knocking-out of dust from loading apertures is particularly acute especially. Work is devoted to improvement of methods of calculation of aspiration when loadings bunkers of silage type by polydisperse material. New statistical approach to the accounting of conditions of constraint on coefficient of front resistance of particles in the conditions of a free stream of the falling material is offered. When falling a free stream of material of a particle of larger fractions shade small and dust particles which aerodynamic resistance in such conditions isn´t considerable. Analytical conclusion of probability of active impact on air of the particles which are out of an aerodynamic shadow that allows to receive a technique of assessment of ezhektiruyushchy ability of a stream of particles at dust removal of bunkers of silage type has been offered. At further development of this approach a conclusion of probability of aerodynamic interaction of particles of polydisperse material is possible. The accounting of dispersion of the overloaded material will allow to calculate optimum amount of aspiration air and to reduce energy consumption of systems of aspiration.

Experimental XRF Calculation Method with Correction for a Polydisperse Material Particle Size

A new experimental calculation method for polydisperse (i.e. heterogeneous) multicomponent material analysis has been developed using the dependence of element fluorescence intensity on the particle size and its distribution in the specimen. It is shown that correction of the influence of matrix particle size is possible using this experimental calculation method. For its application, the information on particle size distribution for each of the components is sufficient. Sample preparation includes only the pelleting of specimens under standard conditions. The efficiency of the method proposed is demonstrated by the analysis of the multicomponent mixtures of welding materials.