EP0318053A1 - Method of and device for separating a grain mixture - Google Patents

Abstract

A process and a device for separating mixed corn, for example for separating heavy admixtures such as stones (28) from grain, in which the grain is conducted in layers over an inclined vibrating layering table surface traversed by a current of air and the layering air is conducted as a circulating air, whereby the circulating air used for layering grain is conducted through separated ducts for the incoming and outgoing air and the ducts are set in vibration in synchronization with the layering table surface.

Description

The invention relates to a process for separating grain mixture, e.g. for reading out heavy admixtures such as stones from grain material, in which the material is guided in a layered manner over an inclined, air-flowing, vibrating layer table surface, and the layer air is conducted as circulating air.

From GB-PS 1 536 905 a grain separating device operating in recirculation mode is known, which essentially consists of a vibrating table surface and a stationary box completely enclosing the table surface. The lower part of the stationary box has a fan, by means of which the air is blown upwards through the table surface. The air flowing out from the top of the table surface is directed laterally between the swinging table surface and the walls of the stationary box back into the fan inlet. The air is circulated. This is called recirculation mode. This has the great advantage that complex aspiration systems with appropriate filter devices for the stratified air. The fact is, however, that until now these air circulation systems have only been able to establish themselves to a very limited extent.

In general, it has been found that the recirculating air devices are either complex in construction or it is not possible to provide sufficient separation quality, e.g. to achieve a sufficiently high degree of selection for stone selection. The reason for this partly lies in the fact that for the recirculation mode, compromises are made for the product guidance, especially the introduction and execution of the product as well as for the air guidance. So that the vibrating table can swing freely, there must either be sufficient play between the vibrating and the stationary parts or flexible rubber bands must be attached around the entire table surface, which, however, negatively influence the vibrating behavior of the table. False air regularly interferes with the formation of a good product stratification and thus the success of the separation of the various good parts. The actually unsolved point was the accumulation of dust, dirt and shell parts within the stationary box. The type of devices mentioned is predominantly those for the separation of grain and other seeds from foreign stock, e.g. 1-2% third-party stocking is quite common. With throughputs of e.g. 5-20 tons per hour also result for the annoying small stocking, large quantities. Air recirculation systems therefore place higher demands on the operator due to the greater expenditure for cleaning; otherwise they are problematic in terms of hygiene. Therefore, only great practical disadvantages remained of the theoretical advantages. In the known recirculating air devices, dust-laden air often escaped into the environment because the pressure conditions were not adequately controlled.

The invention has for its object a new in To create a circulating air separation process that allows a high throughput while reducing the disadvantages of the known solutions as much as possible.

The invention is achieved in a generic method in that the circulating air used for the stratification of the material is passed through separate guides for the supply and exhaust air, the guides being set in common vibrations with the table surface.

In addition to achieving the stated object, the invention has the advantage of a high separation quality, a simple structure and a clean operation.

The formation of a vibrating unit of the shift table and air ducts has the very special advantage that with a "little more" of vibrating mass almost every starting point for the deposition of dust etc. is effectively avoided. It is not just the effect of the air that sweeps the dust away. Due to the vibration of all wall parts that come into contact with dust, they are constantly shaken clean.

A particularly surprising advantage for the vibrating unit has been the attachment of the product feed in the area of the higher table end and the air extraction, for example in the middle area above the shift table, and also the air recirculation over the lower area of the shift table. Each of the functions can be geared to the maximum, which until now was only possible with the best individual machines without air circulation. The cascade-shaped, swinging product feed or product feed, widened from top to bottom, ensures that the product is fully spread and loosened right from the start, while at the same time functioning as an airlock. The installation of the product feed cascade in the area of the Higher table ends ensure unobstructed and therefore manageable flow conditions not only through, but also above, the entire shift table area. The air recirculation in the form of a circulating air supply duct, which is guided around the lower end of the table and opens out below this, also ensures optimal flow conditions. However, it is also very particularly important that the circulating air is conducted to and from the shift operation in a manner which is free from jolts and is essentially eddy. The circulating air can now be cleaned in stationary facilities as required. Since the air in question remains in the circuit, mechanical cleaning without filtering is sufficient. However, it is also possible to pass only a small proportion of the circulating air into a dust filter. This also has the advantage that the entire system remains under negative pressure to the outside.

For the various further advantageous configurations, reference is made to claims 2 to 7.

The invention further relates to a device for separating grain mixtures, in particular for reading out heavy admixtures, such as stones from grain material, with an air-flowed, oscillatable, inclined shift table with air guides for circulating air operation of the device, and is characterized in that the shift table and the guides for air extraction and air recirculation form a vibrating box.

It was really a surprise for the experts involved that all the disadvantages mentioned at the outset have been eliminated with the new separating device operating in the recirculation mode.

The fact that not only the parts that are functionally necessary for the separation task are set in vibration, but also the supply and exhaust air ducts for the Air, the problem of dusting the device is effectively eliminated. The fine dust simply passes through the device. An easy-to-control swingarm box can be formed, on which each function receives a clear local assignment. The material feed is preferably arranged on the side of the higher end of the shift table. On this side, the shift tables can be pulled out for service work. The air return is preferably attached to the other lower end side. This can be designed as a flat channel, so that air flowing out of it enters the lower table surface in a vortex-free manner. The air extraction is installed in the upper middle area of the box. The good and fluid connection of the vibrating parts with the stationary parts can be done by round fabric or rubber sleeves, as is done in practice with many vibrating machines without problems.

For further advantages, reference is now made to claims 9 to 15.

A very particularly advantageous design idea is that one or two table surfaces can be attached in the same swinging box, the lower table taking over part of the goods of the upper table, and the product transfer can preferably take place at the higher table end.

The upper table surface can also - possibly even additionally - have a trough-shaped depression (stone or manor swamp) with through-openings in the trough bottom to separate the product flow into a heavy and a light fraction in its lower area. The transfer of goods from the upper to the lower table takes place in this case via a slide arranged in the opposite direction to the main flow direction of the upper table, which on the lower table flows.

With the invention, a high degree of grain separation, especially stone reading, can be achieved. In addition, little air is advantageously used, and the method and the device are simple and, in particular, not very sensitive to fluctuations in throughput and do not dust inside.

• Fig. 1 die einfachste Form eines Kleintischauslesers für Steine,
• Fig. 2 die Produkteinspeisung auf den Schichttisch,
• Fig. 3 denselben Lösungsansatz wie Fig. 1, jedoch mit zwei Tischflächen, besonders für einen großen Produktdurchsatz,
• Fig. 4 eine Lösung gemäß Fig. 1, jedoch mit einem Umluftkanal,
• Fig. 5 eine Lösung gemäß Fig. 3, jedoch mit einem Umluftkanal,
• Fig. 6 die Fig. 5 mit Umluftabscheider,
• Fig. 7 ist eine Lösung ähnlich Fig. 3 mit zusätzlicher Bildung von zwei Schwerefraktionen nebst der Steinauslese,
• Fig. 8 ist eine Ausführungsvariante zu der Fig. 7,
• Fig. 9 zeigt einen Steinsumpf auf der Schichttischflä­che,
• Fig. 10 zeigt die Vorrichtung wie bei den Fig. 3, 7 und 8 mit durch den Kasten geführtem Umluftka­nal.

Some exemplary embodiments of the invention are explained in more detail below. It shows

• 1 the simplest form of a small table reader for stones,
• 2 shows the product feed on the shift table,
• 3 the same approach as FIG. 1, but with two table surfaces, especially for a large product throughput,
• 4 shows a solution according to FIG. 1, but with a circulating air duct,
• 5 shows a solution according to FIG. 3, but with a circulating air duct,
• 6 shows the FIG. 5 with circulating air separator,
• 7 is a solution similar to FIG. 3 with the additional formation of two heavy fractions in addition to the stone selection,
• 8 is an embodiment variant of FIG. 7,
• 9 shows a stone sump on the layer table surface,
• Fig. 10 shows the device as in Figs. 3, 7 and 8 with the recirculated air duct guided through the box.

In the following, reference is now made to FIGS. 1 and 2. 1 shows a basic type for a new stone reader 1, the fresh grain being passed through an inlet 2 to a shift table 3 and from there as cleaned grain via an outlet 4 is dissipated. A closed hood 5 is arranged above the shift table 3 and has a suction opening 6. The hood 5 forms, together with the shift table 3, an oscillating device 7 which can be set in motion by a vibration exciter 8 with an oscillating component in the direction of the upper end of the shift table 3. The upper end of the layer table 3 is formed by a guide plate 19 as an end separation zone. The entire vibrating unit 7 is supported by spring elements 9 on a frame 10 which is fixed on a floor 11. Also fixed to the frame 10 is a non-vibrating head piece 12, in which the inlet 2 and an air suction line 13 are attached. Furthermore, an air quantity adjustment flap 14 is arranged in the air suction line 13 for setting the air aspirated by the entire stone reader 1. The connection of the vibrating parts, or the vibrating unit 7 and the head piece 12, takes place via flexible sleeves 15, which are arranged after the inlet 2.

When viewed in plan, the layer table 3 preferably has an at least approximately rectangular shape. On the side of the higher end of the shift table, the shift table 3 can be pulled out for service work. The product transfer point extends across the full table width. The width is designated in FIG. 2 with "B", the layer thickness with "D". The formation of a wide-area flow of goods 20, also called a good veil, for the purpose of feeding the goods takes place in two stages. As part of the swinging hood 5, the fresh grain is guided in a distribution box 17. The vibration promotes the uniform, wide distribution of the grain in the distribution box 17, which is widened downwards to reinforce this effect, is cascaded. The same purpose is served by a stowage flap 18, which is also provided in the distribution box 17, so that the grain material already as a wide-area product stream directly onto the guide plate 19 which extends over the entire table width and then is passed as a uniform, broad product stream 20 onto the shift table 3. The widespread spread of the product stream 20 is further supported by the fact that the guide plate 19 has an overflow edge 16 at its free end, that is to say it is trough-shaped. To pre-separate heavy and light goods, the trough-shaped guide plate 19 can also have bottom openings for the passage of the heavier admixtures.

The broad, uniform product flow spread on the shift table 3 is particularly illustrated in FIG. 2. The stratification is deliberately overemphasized in the same figure. The layer table 3 has a rough mesh screen 21 as a product support and is constructed in a manner known per se in the so-called sandwich construction, the mesh screen 21 forming the upper side, supported by honeycomb-shaped sheet metal strips 34 which are held downwards by a fine perforated plate 22 . In the individual fields 23 between the metal strips 34, cleaning bodies 24 are arranged which keep both the mesh 21 and the perforated plate 22 clean. It is also important here that the perforated plate 22 has an air resistance that is much greater than the air resistance of the mesh 21, z. B. in the order of 1: 10. With this measure, the air distribution can be kept approximately constant over the entire surface of the layer table 3 regardless of the layer thickness on the mesh screen 21.

The material stratification itself essentially consists of three different layers, a lower, heavy layer 25 containing the heavy admixtures being conveyed upward by the mechanical throwing motion. A light layer 26 freed from the heavy admixtures is kept in suspension not only in the relaxed state but also at a distance above the mesh 21 by the targeted air flow. There the layer table 3 is slightly inclined and the upper light layer 26 does not directly receive an upstream table impulse, but is kept in vibration, it swims towards the lower-lying table side. In addition, the inclination of the shift table 3 can be adjusted by an adjusting device 35. A third layering 27 consists of the actual heavy admixtures, usually only individual particles, individual foreign bodies, stones 28, etc. Good, heavy grains 29 and light parts, e.g. B. half grains, shell parts 30 are shown in the approximately corresponding shape. The heavy material with the stones 28 immediately sinks onto the vibrating table surface 7 and moves up the table due to the vibration and the rough table surface designed as a mesh 21.

For the function described, it is now important that the air flow is guided correctly. The entire surface of the shift table is flowed through uniformly from bottom to top by a suction air flow, the direction of flow of which is illustrated by arrows 31. This air flow 31 brings the grain to a highly fluidized state. Since only the heaviest parts, i.e. H. the stones 28 are separated on the higher end of the table and are to be conveyed from there to a stone lock 45, a corresponding blow-back flow 33 is formed, which prevents light parts or grains with the heaviest admixtures from being conveyed upwards. The blow-back stream is preferably formed under the guide plate 19. If the guide plate 19 is firmly connected to the hood wall, the air guided into the slot between the guide plate and the shift table can only escape in the direction 33.

With the exception of the stones 28 located therein, the material is prevented from moving further upwards by the air flow in front of the final separation zone. The stones 28 can continue their movement towards the higher end of the table Zen.

The same blow-back flow 33 causes a flow front or flow direction reversal 32 which is clearly established in practice. At the location of the flow direction reversal 32, the grain 29 freed from the stones 28 is lifted off the table surface by the strong air flow 31, 33 and now flows freely together with all light goods with the upper lifted light layer 26 down the table. The lightest fraction is discharged immediately at outlet 4; an average grain fraction can possibly make a circular traveling movement up-table-down several times, which is particularly true for boundary grains.

In FIGS. 1 and 2, the product stream 20 is fed directly into the zone of the flow direction reversal 32. The flow direction reversal 32 is generated from the three forces of mechanical conveying action up-table, floating of the upper layer 26 down-table and blow-back flow 33.

The main structural difference between FIG. 3 and FIG. 1 is that in FIG. 3 two shift tables, an upper shift table 3a and a lower shift table 3b are used. Basically, both shift tables 3a and 3b have the same structure, e.g. B. as in FIG. 2. In principle, the top blow table 3a lacks the blow-back flow 33, so that not only the heaviest admixtures, but the whole heavy layer 25 can be moved up the table and can fall onto the guide plate 19 through a discharge channel 40 via a steering plate 41. Starting from the guide plate 19, the mode of operation of the shift table 3b is identical to that of the shift table 3 of FIGS. 1 and 2.

In order to prevent the freshly entering product stream 20 from the distribution box 17 from being mixed directly with the heavy layer 25, there is between the distribution box 17 and the layer table 3a, a guide plate 42 is arranged at the uppermost point.

The flowing product stream is drained via a product lock 43 directly into an outlet channel 44 of the lower layer table 3b. The two streams of material from the two shift tables 3a and 3b freed from the heaviest admixtures are then brought together again in the outlet 4. All heaviest admixtures, such as stones 28, etc., are first separated from the upper layer table 3a together with the heavy layer 25. The actual separation and the separate removal of the stones 28 via the stone lock 45 then take place on the lower layer table 3b. The stone selection takes place here in two temporally and spatially separated stages. This is because concentrate is first formed with all heavy goods, e.g. B. 30% to 60% of the entire material throughput on the upper shift table 3a and only from the reduced material throughput the stones and other heaviest admixtures are read out and carried away separately.

FIG. 4 is identical to FIG. 1 in terms of product management, and FIG. 5 corresponds to FIG. 3. The solution concept of FIGS. 4 and 5 additionally contains an all-round closed box 50, which can be closed by the, respectively the shift table (s) is divided into an upper suction chamber 51 and a lower suction chamber 52. Laterally at the lower end of the or the shift table (s) is a recirculation channel 53, which is connected via a flexible hose 54 and an air return pipe 55 'to an air return line 55. An air flow restrictor 56 is arranged in the air return line 55. 4 and 5, the box 50 itself is supported on the stationary frame 10 by means of spring elements 9. At the top of the box 50 is on one end side of a Guteinlaufstutzen 2 adjoining the Guteinlauf 2 ', approximately in the middle with the air suction line 13 interconnected air suction 13 'and on the opposite end side an air return pipe 55' connected to the air return line 55 'is arranged. The aforementioned connections 2 ', 13', 55 'are connected via flexible sleeves 15, 54 on the one hand to the non-vibrating head piece 12 and on the other hand to the box 50 in order to be able to participate in its movement in this way. In the double machine in FIG. 5, two outlets 4 are arranged as tubular product channels 57 on both sides (perpendicular to the image plane), so that the remaining space between the two product channels 57 remains for the circulating air channel 53. The box 50 is bordered in Figures 4 and 5 for better identification with a dashed line.

In addition to FIGS. 4 and 5, FIG. 6 additionally shows a circulating air separator 60 with a suction fan 61 and a motor drive 62. The air suction nozzle 13 leads directly into the circulating air separator 60, the essential or disruptive part of fine shells and dust being removed from the air flow via a dust discharge line 64.

In most cases where recirculated air is used, air cleaning is advantageous because it can effectively prevent dust accumulation in the entire device and increase operational safety and hygiene. The recirculation mode has the great advantage that only a minimal amount of air, e.g. B. 10% of the circulating air volume must be passed through fine dust filters. For this purpose, an aspiration connection 65 is provided. The circulating air separator 60 can be attached directly to the ceiling 66 with a fan.

Fig. 7 has a fundamental difference compared to Fig. 3 insofar as in Fig. 7 only a small part of the material throughput from the upper shift table 3c at the highest point through a series of larger holes 71 across the entire table width is given to the upper zone of the flow direction reversal of the lower layer table 3d. The majority of the heavy goods are guided in the area of the lower end of the table via a chute 72 approximately to the middle of the lower layer table 3d, again over the entire width of the table. Many series of measurements have shown that, with this solution, the large part of the stones is nevertheless released through the holes 71 directly onto the lower layer table 3d. In the solutions according to FIGS. 7 and 8, it is important that the upper layer table only has a less rough surface than the lower layer table 3d, as shown in FIG. 9, by the upper layer table 3c made of perforated sheet metal and the lower layer table 3d is formed from mesh.

A particularly interesting, independent idea is now shown in FIGS. 8 and 9. This is the use of a stone sump 80 in the area of the upper layer table 3c. The method of operation is as follows: The stone sump 80 consists of a trough-like depression 81 which extends over the entire width of the layer table 3c. Similar to FIG. 2, two different layers are formed in FIGS. 8 and 9, namely the heavy layer 25 and the light layer 26 freed from the heavy additives.

• 1. Es ergibt sich auf diese Weise ein sehr hoher Auslesegrad für die schwersten Beimengungen (Steine, usw.)
• 2. Es kann mit nur einem minimalen Mehraufwand zusätzlich zu der Abtrennung der schwersten Beimengungen in eine saubere schwere Fraktion (gute Körner) und den Rest in eine leichte Gutfraktion (Schalen, Schmacht- und Bruchkörner) getrennt werden.

Because the surface of the upper layer table 13 has only a slight roughness, there is no actual upward flow; at least the whole heavy layer 25 cannot be moved up. Rather, the lower heavy layer 25 flows down the table in a greatly delayed manner, as is indicated by the single arrow 82. In contrast, the light layer 26 flows down the table at high speed (double arrow 83). The heavy layer now sinks, once it has reached the area of the recess 81, into the stone sump 80. The stone sump 80 now has a number of through openings 84 on its bottom, through which part of the material passes is continuously discharged together with the stones onto the underlying slide 72 or the lower layer table 3d. With the correct coordination of the number of effective diaphragm openings 84 in relation to the mass flow of the heavy layer, the light and heavy layers can be separated in such a way that the heavy layer 25 continuously sinks completely into the stone sump 80 and is discharged directly downwards. This has two major advantages:

• 1. This results in a very high degree of selection for the heaviest admixtures (stones, etc.)
• 2. In addition to separating the heaviest admixtures, it can be separated into a clean, heavy fraction (good grains) and the rest into a light good fraction (shells, grainy and broken grains) with only a minimal additional effort.

This makes it possible to separate the different basic fractions (stones, etc., heavy, light) in a single device and with very high quality.

Finally, FIG. 10 shows a device which operates on the same principles as the devices according to FIGS. 3, 7 and 8. For this reason it is not necessary to repeat the description of the same components at this point. 10 differs from the aforementioned devices only in that a recirculation duct 53 'is arranged separately in the box 50, and the influence it has on flow properties of the air in the box 50 can be avoided.

Claims (18)

1. A method for separating grain mixture, for example for reading out heavy admixtures such as stones (28) from grain material, in which the material is essentially layered and passed over an inclined, air-flowing, oscillating layer table surface and the layer air is conducted as recirculating air, characterized in that the circulating air used for the stratification of the material is passed through separate guides for the supply and exhaust air, the guides being set in common vibrations with the table surface. 2. The method according to claim 1, characterized in that the guides together with the shift table (3; 3a, 3b; 3c, 3d) form a box (50) which is set in vibration. 3. The method according to claim 1 or 2, characterized in that a stationary platform (12) and above a stationary fan (61) is arranged above the vibrating box (50), wherein the air circulation of the circulating air is maintained by the fan (61) . 4. The method according to at least one of the preceding claims, characterized in that part of the grain mixture is passed to a further layer table (3b; 3d) arranged below the layer table (3a; 3c), the circulating air flowing through both layer tables. 5. The method according to at least one of claims 1 to 4, characterized in that the material is fed as a wide-area stream in the region of the higher table end, the exhaust air is discharged in the top center and the supply air in the area of the lower end of the shift table is supplied again over a wide area. 6. The method according to at least one of claims 2 to 5, characterized in that the material is fed in as a uniform falling stream extending over the entire table width and the intended material feed (17, 19) is firmly connected to the oscillating box (50), is designed as a cascade widened from top to bottom. 7. The method according to at least one of claims 1 to 6, characterized in that the circulating air in the region above the central air discharge (13 ') in stationary elements of dust parts is cleaned. 8.Device for separating grain mixtures, in particular for reading out heavy admixtures, such as stones (28), from grain material with an air-flowed, inclined layer table (3; 3a, 3b; 3c, 3d) which can be vibrated and with air guides (13 ', 53) for circulating air operation of the device, characterized in that the layer table (3; 3a, 3b; 3c, 3d) and the guides (13', 53) for the air extraction and for the air return form a vibrating box (50) . 9. The device according to claim 8, characterized in that within the box (50) are provided: an air suction space (51) above the shift table (3; 3a; 3c) and a separate air supply duct (53) which in the area of lower end of the shift table (3; 3b; 3d) opens. 10. The device according to claim 8 or 9, characterized in that a widened from the top down, cascade-shaped feeder (17, 19) is part of the vibrating box (50) which is arranged in the region of the higher table end. 11. The device according to at least one of claims 8 to 10, characterized in that on the top of the box (50) at one end a Guteinlaufstutzen (2 '), approximately in the middle of an air suction (13') and on the opposite end Air return pipe (55 ') are arranged. 12. The device according to at least one of claims 8 to 11, characterized in that in the box (50) at least two layer tables (3a, 3b; 3c, 3d) are arranged one above the other, with the circulating air flowing through both shift tables from bottom to top, and a product transfer (40, 19; 43; 71; 72; 81, 84) for transferring part of the goods of the top shift table (3a; 3c) to the bottom Layer table (3b; 3d) is provided. 13. The device according to at least one of claims 8 to 12, characterized in that the material supply and / or the product transfer over the entire width of the shift table (3; 3b; 3d) opens, and the mouth at a distance above the shift table (3; 3b; 3d) arranged guide plate (19). 14. The device according to at least one of claims 8 to 13, characterized in that the box (50) is oscillatably mounted on a frame (10) which has a stationary head piece (12) in its upper region. 15. The apparatus according to claim 14, characterized in that between the stationary head piece (12) on the one hand and the air extraction nozzle (13 ') or the air return nozzle (55') and the Guteinlaufstutzen (2 ') on the other hand of the vibrating box (50) flexible cuffs (15; 54) are arranged. 16. The apparatus according to claim 14 or 15, characterized in that a circulating air separator (60) is arranged above the stationary head piece (12). 17. The apparatus according to claim 16, characterized in that the circulating air separator (60) with a suction fan (61) and with a dust guide line (64) is connected. 18. The device according to at least one of claims 8 to 17, characterized in that the circulating air duct (53) is connected to an aspiration connection (65) for fine dust filters.

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