RU2193929C1 - Channel for separating grain with ascending air flow - Google Patents

Abstract

FIELD: agricultural and food engineering, flour-milling and feed-mill industry. SUBSTANCE: channel has front, rear and side walls, net inclined from front wall toward rear wall, windows for receiving basic grain material and discharging processed grain material. At least one barrier is positioned transverse to side walls above net. Space s between net and barrier lower edge is correlated with average thickness d of particles of material under process and depth l of channel by ratio of 3d<s>l, and distance t from front wall to first barrier and adjacent barriers meets ratio of s<t<0.75 l. Channel of such construction is used for cleaning grain, seeds and other kinds of bulk materials. EFFECT: increased efficiency in grain separation due to stabilized air flow speed through the entire depth of channel. 2 cl, 2 dwg

Description

 The invention relates to techniques for the separation of grain and other bulk materials by air flow and may find application in the purification of grain and seeds in agriculture and grain processing products in the milling and cereal and animal feed industry, and other industries.

 Known pneumatic separation channel for grain separation by the ascending air flow formed by the front, rear and side walls. There is a loading window in the front wall for introducing the source material into the channel, and for opening the heavy fraction from the channel, the open lower part of the channel itself is used (Seed Cleaner SVU-5 in the book: MS Kulagin et al. Mechanization of post-harvest processing and storage of grain and seeds M.: Kolos, 1979, p. 35).

 The disadvantage of this channel is the low separation efficiency of the grain material - the proportion of the light component emitted by the air flow usually does not exceed 70-80% with the permissible removal of full grain to waste.

 Studies of the operation of such a channel showed that the separation of grain material cannot be improved by increasing the channel cross-sectional area due to its depth (i.e., the distance between the front and rear walls), since the uneven distribution of the air flow velocity over the channel depth increases. The air velocity in the channel near the front wall where the grain material is introduced is not high enough for the effective removal of light particles due to the high resistance of the relatively dense grain flow, while at the opposite wall, where the grain jet has already been distributed in height into the easily blown stream, the air speed is too high, which leads to the removal of an increased amount of complete grain along with the light component (A.Ya. Malis and AR Demidov. Machines for cleaning grain by air flow. M: Mashgiz, 1962, p. 30-56, fi 17, 29-30).

 In this regard, the productivity of the air separation channel is increased mainly due to the width of the channel, which determines the large dimensions of the machines, the complexity of uniform loading across the channel width and a decrease in the separation efficiency of grain material in comparison with machines with lower productivity.

 In production pneumatic separating machines used to date, the channel width, as a rule, is many times greater than its depth.

 The closest in technical essence to the claimed device is the channel selected for the separation of grain by an upward air flow formed as a prototype, formed by the front, rear and side walls, containing a grid installed with an inclination from the front wall to the back, and a window for receiving the initial and output of the processed grain material.

 This device provides a higher quality of pneumatic separation, because a channel is used in the channel to support the separated material, installed with an inclination to the rear wall, and the heavy fraction output window is made at the rear wall of the channel (OPS-2 cleaning pneumatic sorting column, in the book: M.S. Kulagin et al. Mechanization of post-harvest processing and storage of grain and seeds. M: Kolos, 1979, p. 71).

 The use of the mesh in the channel improves the separation process, provides a slight increase in the efficiency of separation of the grain material due to the fact that the mesh, having resistance to air flow, helps to equalize its speed along the depth of the channel and, in addition, does not allow the grain material to exit the channel down immediately after entry without proper separation.

 At the same time, the main reason for the low separation efficiency of the grain material is the large unevenness of the air flow velocity along the channel depth, which is formed as a result of interaction with the grain flow, the use of the grid is not largely eliminated.

 The objective of the invention is to increase the efficiency of separation of grain material.

 The required degree of uniformity of the distribution of the air flow velocity along the channel depth and the corresponding increased efficiency of separation of grain material in the channel are provided by stabilizing the density of the processed grain flow along the channel depth using barriers.

 The essence of the invention lies in the fact that in the channel for separating grain upward air flow formed by the front, rear and side walls, containing a grid mounted with an inclination from the front wall to the rear, and the window for receiving the source and output of the processed grain material, according to the invention across at least one barrier is installed on the side walls above the net with a gap. In addition, the gap s between the grid and the lower edge of the barrier is related to the average thickness d of the particles of the processed material and the channel depth l by the ratio 3d <s <l, the distance t from the front wall to the first barrier and between adjacent barriers satisfies the relation: s <t <0, 75l; the barrier width h is related to the gap s by the ratio 1 <h / s <10.

 Comparison of the claimed device with the prototype shows that the presence of barriers installed across the side walls above the grid with a gap and the ratio of s, d, l, t, h is new.

 Barriers (one or several, located one after another) are placed above the grid with a gap and at a certain distance from the front wall and from each other.

 The stabilization of the density of the grain flow processed in the channel entering the channel through the receiving window and weighed by the ascending air stream is achieved by the fact that when the grain stream meets the barrier, the bulk of the grain is delayed by its frontal surface and falls onto the grid, being distributed by a layer that is close in density to the incoming from the window to the grid section to the barrier. Therefore, the grain flow coming out from under the barrier in the channel section following it has approximately the same resistance to the air flow as in the previous section. By setting a sufficient number of barriers, determined depending on the depth of the channel used, the required density stability of the processed grain flow over the entire depth of the channel is ensured, which is the main condition for a uniform velocity field of the air flow and, therefore, high efficiency of the process of separation of grain material.

 The efficiency of the pneumatic separation channel, the stability of the quality indicators of the separation process and the reliability of the process during the processing of grain materials of various crops are provided by rational ratios linking the main parameters of the barriers and their placement in the channel.

 Thus, the claimed device meets the criterion of "novelty."

 The present invention meets the criterion of "inventive step", since a result is achieved that satisfies the existing need: increasing the efficiency of separation of grain material.

 The invention meets the criterion of "industrial applicability", because it can find application in the purification of grain and seeds in agriculture and grain processing products in the milling and cereal and feed mill industries, and other industries.

 The invention is illustrated by drawings, where in FIG. 1 shows a vertical section of the channel along the direction of movement of the processed material; in FIG. 2 is a vertical section through a channel perpendicular to the plane of FIG. 1.

 The channel for separating grain by upward air flow, formed by the front 1, rear 2 and side 3 and 4 walls, contains a grid 5 for supporting the separated material, a window 6 for inputting the source material into the channel made in the front wall 1 above the grid 5, and a window 7 to withdraw the heavy fraction from the channel at the opposite wall 2. Above the grid 5 across the side walls 3 and 4, barriers 8 are installed.

 The barrier 8 can be made, for example, in the form of a rectangular, flat metal sheet and attached to the side walls 3 and 4 of the channel or in the form of a rectangular mesh, perforated sheet and other elements that functionally act as a barrier that prevents the free movement of the grain flow incident on it.

 The barriers 8 are mounted above the net 5 with a clearance s sufficient for passage of the processed grain material along the inclined net 5.

 The gap s between the grid 5 and the lower edge of the barrier 8 is associated with the average thickness d of the particles of the processed material and the channel depth l by the ratio 3d <s <l.

The distance t from the front wall l to the first barrier 8 and between adjacent barriers satisfies the relation: s <t <0.75l
The width h of the barrier 8 is related to the gap s by the ratio 1 <h / s <10.

 The workflow is as follows.

 The initial grain material, consisting of grain and subject to separation of lighter impurities than grain, is fed through a loading window 6 into a channel, where it is exposed to an upward air flow, pumped from the bottom of the channel or sucked off from above by an air flow generator (not shown) . As a result of the upward flow of air the grain material acquires the state of a fluidized bed in which it moves from the front wall 1 to the back 2, stratified into fractions. Particles of a light fraction (impurity) float into the upper layers of the grain flow, and heavier particles (main grain) remain in the lower layers of the processed material stream above the supporting grid 5, touching it to one degree or another, depending on the air flow velocity.

 When such a fan-shaped flow of grain material meets the first barrier 8, its lower layers, consisting mainly of grain, stop moving toward the rear wall 2, drop downward on a layer 5, where the process of further isolation of light particles resumes. This grain flow, having descended on the grid 5, creates a higher than fan-shaped resistance to the air flow passing through it in the area between the first and second barriers 8, thereby reducing the air flow rate, bringing it closer to the level as in the area of the grid 5 between the front wall and first barrier 8.

 Another part of the grain material, located at higher and less dense levels of the grain flow and containing more light particles, is reflected from the surface of the barrier, after which the grains are lowered onto the grain stream, and light impurity particles are lifted by the air stream and carried out of the channel through the upper outlet.

 Another part of the flow of the processed material, moving above the barrier 8, continues to move in the air flow up to the exit and to the rear 2 wall of the channel. This part of the stream contains predominantly light particles.

 In the section of the channel between the first and second barriers 8, the process of separation of the material received on the grid in the gap between the grid and the first barrier is carried out in the same way as in the section between the front 1 wall and the specified barrier 8.

 The second barrier 8, like the first, deposits the main part of the grain flow on the mesh 5 with a layer, increasing its resistance to air flow and stabilizing its speed in the final section of the channel between the second barrier and the rear wall. As a result of creating favorable conditions for a uniform air velocity throughout the depth of the pneumatic separating channel, a better process is carried out than with an uneven air stream, the separation of grain material — the cleaned grain exits through window 7, and the light component (impurity) is carried out by air from the channel through top exit.

 The optimal operating conditions of the air separation channel, providing the maximum separation efficiency of the grain material when processing various crops, are determined by the above ratios of the main placement parameters and the size of the barriers and the depth of the channel.

 The proposed device can significantly increase the separation efficiency of the grain material.

Claims (2)

 1. Channel for separating grain by an upward air flow formed by the front, rear and side walls, containing a mesh installed with an inclination from the front wall to the rear and windows for receiving the initial and output of the processed grain material, characterized in that across the side walls above the mesh with a gap at least one barrier is installed, and the gap s between the grid and the lower edge of the barrier is connected with the average thickness d of the particles of the processed material and the channel depth l by the ratio 3d <s <l, and the distance t from the front wall and to the first barrier and between adjacent barriers it satisfies the relation s <t <0.75l.  2. The channel according to claim 1, characterized in that the barrier width h is connected to the gap s by the ratio 1 <h / s <10.

Images