RU2403099C2 - Method of loose materials separation - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to agriculture and is intended for grading and cleaning seeds and can be used for separation of loose materials. Loose material separation on one or several fixed screw surfaces consists in that mix is fed onto screw surface by chute, separation is performed by moving mix components along different trajectories depending upon shape and state of particle surfaces, fractioning is performed at the screw surface outlet by movable separators. Round-shape components are graded to elasticity and sphericity. Note here that round-shape components are imparted stick-slip motion. Mix is fed onto screw surface at an angle. Mix is fed onto screw surface by chute arranged with a gap above said surface. Mix is fed onto screw surface at the rate that corresponds to round-shape component rate and along stable trajectories.

EFFECT: higher efficiency.

4 cl

Description

The invention relates to agriculture and is intended for cleaning and sorting seeds. The invention can be applied to the separation of other bulk materials.

A known method of separating a grain mixture in shape and state of the surface of the particles on several helical surfaces located in tiers, according to the system of multi-pass screw, which consists in the following. Grain mixture from the hopper is fed by gravity to the screw surface. Under the influence of gravity and centrifugal forces, rounded seeds that experience rolling resistance develop greater speed and are further removed from the axis of the surfaces than seeds that are flat, elongated, experiencing slip resistance. With steady motion, seeds move along a helical surface at a constant speed, along stable trajectories, helical lines. Seeds whose stable trajectories extend beyond the helical surface are extracted through the outer edge of the helical groove and sent to the collector. The remaining seeds, seeds with a high coefficient of resistance to movement, descending along a helical surface closer to its axis, are sent to another collection through the lower edge of the surface (Letoshnev MN Agricultural machines. Theory, calculation, design and testing. M. - L., 1955, p.689-695. Sablikov MV Agricultural machines. Fundamentals of theory and technological calculation. M., 1968, p.232-234).

The disadvantage of this method is the separation of the mixture by only one constant boundary between the components.

There is also a method of separating particles on a helical surface, namely, that the particles are fed to the helical surface by a tray, the separation is carried out by ensuring the movement of particles along different paths depending on the coefficient of friction of the particles, the division is carried out at the exit from the helical surface by dividers into several fractions (patent US No. 3910835, CL B07B 13/10, 1975).

The disadvantage of this method is that the output of the conditioned fraction and its quality can be adjusted only stepwise due to the immobility of the dividers, which, in turn, does not allow to fully realize the separating ability of the screw surface.

The closest in technical essence and the achieved result is a method of separation of bulk materials, which consists in the fact that the mixture is fed to the helical surface by a tray, the separation is carried out by ensuring the movement of the components of the mixture along different paths depending on the shape and condition of the surface of the particles, the division into fractions is carried out descending from the screw surface with dividers installed with the possibility of movement (RU No. 20177552, class B07B 13/10, 1994).

The disadvantage of this method, as described above, is the relatively low separation efficiency in the selection and sorting of round-shaped components. This is explained by the fact that when the feed is increased above a certain value, the mixture will move along the helical surface in a dense stream. Even when a layer moves in one particle, some particles may be entrained by others. In this case, rounded particles, like flat ones, moving in areas of a helical surface in a dense flow, will experience sliding resistance, since in order to roll over the surface, in addition to rolling resistance, it is necessary to overcome the sliding resistance on the surface. As a result, the mixture will move in a constrained flow, overcoming the general sliding resistance, and separation will be almost absent. The separation in this case will occur at the edges of the stream. During separation, particles moving on the surface often collide with each other, which leads to a deviation of their trajectory of movement, and, accordingly, to a decrease in the quality of separation. The deviation of the trajectories will be the greater, the larger the angle at their intersection, the magnitude of which depends on the magnitude of the difference in the coefficients of friction of the colliding particles. The most significant deviations of the trajectories will occur in the collision of rounded particles with flat and oblong.

Various components of a rounded shape often have insufficient differences in the friction coefficients, which do not allow them to be divided into separate fractions.

The objective of the invention is to increase the efficiency of separation from the mixture of components of a rounded shape and sorting them by more efficient use of differences in sphericity and elasticity.

The objective of the invention is solved in that in the method for separating bulk materials on a helical surface, namely, that the mixture is fed to the helical surface by a tray, the separation is carried out by ensuring the movement of the components of the mixture along different paths depending on the shape and condition of the surface of the particles, the division into fractions is carried out at the exit from the helical surface, dividers installed with the possibility of movement, components of a rounded shape give movement in jumps. In addition, in the particular case, the mixture is fed onto the helical surface at an angle, with a tray installed with a gap above it, into the zone and at a speed predominantly corresponding to the movement of particles of rounded components along stable trajectories.

When moving along a helical surface in jumps, rounded particles experience less resistance to movement compared with rolling motion due to the fact that in this case the total length and duration of movement of particles on the surface will be much less, and accordingly, the friction resistance will be less. Moreover, the higher the sphericity and elasticity of a particle, the further its jump will be, the less will be the work spent on overcoming friction, the greater will be the kinetic energy and, accordingly, the speed and radius of the trajectory of its movement along a stable trajectory. Thus, the spasmodic nature of the movement of the components of a rounded shape on a helical surface increases the space of movement of the shared mixture along the width and height of the flow. This helps reduce the likelihood of particle collisions and entrainment of some particles by others. In this case, the probability of collision of rounded particles with particles with a high coefficient of friction sliding on the surface will be significantly reduced, since the trajectories of their movement, being mostly at different levels, in most cases intersecting, do not intersect. As a result, the efficiency of separating round-shaped components from a mixture by sphericity and elasticity on a helical surface and dividing into fractions and sorting at the descent from the surface by dividers installed with the ability to move increases.

The mixture is fed onto the helical surface in the zone and at a speed mainly corresponding to the movement of the particles of the components of the rounded shape by jumps along stable trajectories, which makes it possible to create better conditions for increasing the throughput of the area due to a larger speed regime, a larger radius of motion, and, accordingly, better use of the helical surface in the initial period of movement along it compared to the feed intended for the acceleration mode. The components of the mixture with a large coefficient of friction, as well as less sphericity and elasticity, moving in the braking mode, approach stable trajectories corresponding to helical lines. As a result, the efficiency of separation of rounded particles from the mixture in comparison with the acceleration mode is increased.

The method on the example of a known device (RU No. 20177552, class B07B 13/10, 1994, BI No. 15) is as follows. The separated mixture from the hopper flows by gravity in parallel and equal flows to the trays in tiers, develops corresponding speeds on them and enters the helical grooves. To give the particles a rounded shape in a jumplike motion, the mixture is supplied to the helical surfaces at an angle. Why trays in a particular case are installed above the screw surfaces with a gap. Rounded particles of the mixture, hitting the surface of the gutter, acquire an abrupt motion. On the surface, the mixture is separated as a result of the fact that when the particles move along the helical surface, their trajectories approach stable, radial distances are inversely related to resistance to movement. Particles moving in jumps experience less resistance to movement than particles moving on a surface without separation from it. The more flexible and spherical the particle, the more it moves away from the axis of the helical surface. Using this property allows you to increase the efficiency of sorting grain, which has a rounded shape, since more complete, well-made grains are characterized by greater elasticity and sphericity. Immature, feeble, injured, damaged by pests and disease grains are characterized by reduced elasticity and a greater deviation from sphericity.

Particle with a high coefficient of friction, radial distances of stable trajectories, which are smaller than the radius of the inner edges of the screw surfaces, fall from the helical groove into the axial collector. The remaining particles leave the screw gutters through their lower edges, are divided into fractions by mobile dividers, depending on the requirements for the quality of the finished product.

Changing the feed zone on the helical surface is done by moving the tray along its upper edge. The change in the feed rate of the mixture is made by changing the installation height of the loading device and the inclination of the tray. When the mixture is fed into the zone and at a speed mainly corresponding to the movement of the particles of the components of the rounded shape along helical lines, these particles will more quickly and at a smaller number of turns take motion along stable trajectories than during the acceleration mode. As a result, the efficiency of separation of the mixture on a helical surface and sorting by sphericity and elasticity of the particles will increase.

Claims (4)

1. The method of separation of bulk materials, mainly seeds, on one or more fixed screw surfaces, which consists in the fact that the mixture is fed to the screw surface by a tray, the separation is carried out by ensuring the movement of the components of the mixture along different paths depending on the shape and condition of the surface of the particles, division the fractions are produced at the exit from the helical surface by dividers installed with the possibility of movement, characterized in that the selection of the components of the round shape from the mixture is carried out by elasticity sphericity, give them movement jumps. 2. The method according to claim 1, characterized in that the mixture is fed onto the helical surface at an angle. 3. The method according to claim 2, characterized in that the mixture is fed to the screw surface with a tray installed with a gap above it. 4. The method according to claim 1, characterized in that the mixture is fed onto the helical surface in the zone and at a speed mainly corresponding to the movement of the particles of the components of the rounded shape along stable trajectories.