IL33179A - Discharge arrangement for a silo compartment having a tapering botton section - Google Patents

Description

33179/2 ιη· n»nnn Discharge arrangement for silo compartments having a taperin bottom section GEBRUDER BUHLER AG Cs31396 The invention relates to discharge arrangements for silo compartments in which a transition zone, tapering downwards in two dimensions ,, is interposed between the main part of the compartment and a narrower outlet. In silo compartments of this type, there exists the danger that the bulk material forms bridges in the tapering transition zone, which leads to partial or total clogging. This bridge formation is favoured by the increase of pressure due to the decrease in cross section. The bridges thus formed are often highly compact and difficult to break down, so that the bulk material does not flow out. Fodder ingredients are especially difficult to handle in this respect. These ingredients are mainly in the form of flour or crushed grains, such as, for example, granular oil extraction residues, crushed cotton hulls, bran and other products of a similar nature. The same problem exists with similar products in other industries as well.

With a view to narrowing the danger of bridge-formation it has already been proposed to dispose dividers in the tapering transition zone of the silo compartment.

Thus, for a transition zone of rectangular cross-section, the French patent specification No. 1,396,105 discloses a divider formed by two Intersecting wedges of triangular profile whose upper edges are disposed in the same horizontal plane. This arrangement creates four narrower, strongly tapering flow-channols out of the wider flow channel of the transition zone, and if the formation of bridges across the total width of the flow channel can thus be - lumpy, or are otherwise difficult to handle.

The arrangement of dividers having a triangular German profile has also been described in former patent specifications Nos. 1,117,049 and 1,226,942, but not within a tapering transition zone of the silo. According to the first use of these specifications the dividers are located in the main part of the silo, i.e. in a region of uniform cross-section. According to the second German specification it is the divider bars themselves that create tapering zones but within the lathe, no more dividing arrangements are provided.

The Invention has the object to provide a divider arrangement which effectively prevents bridge-formation and clogging even with bulk materials that are difficult to handle with known discharge arrangements.

The invention consists in a discharge arrangement for silo compartments in which a transition zone, tapering downwards in two dimensions, is interposed between the main part of the compartment and a narrower discharge mouth at the bottom of the compartment and a divider Is disposed in the transition zone , characterized in that i (a) the divider is constituted by two cross bars intersecting at right angles and disposed at two different levels; (b) each cross bar comprises a main part bounded by vertical surfaces, and a wedge-shaped ridge; (c) the ridge of the upper cross bar extends over the entire width of the compartment and its vertical surfaces are located withi the transition zone; (d) the ridge of the lower bar is disposed at such a vertical distance from the rid e of the u er bar that the bottom In this arrangement, the bottom of each cross bar forms a pressure-relieving stage which prevents a pressure from building up.

Favourable flow conditions result in this arrangement from the fact that, on the one hand, at least a part of the discharge opening is located beneath one of the two cross bars and the formation of chimneys is thus avoided, and, on the other hand, the product is divided on its way and, because of the different orientation of the inclined surfaces of the cross bars, no support exists for bridges. Moreover, the pressure-relieving stages at the bottom of each divider bar prevent the occurrence of high pressures.

In an especially advantageous embodiment of the invention the ridge of the upper bar projects from the upper end of the transition zone into the main portion of the silo compartment. In this manner the product is divided before it reaches the inclined wall of the transition zone. Preferably, the line where the ridge of the upper bar merges into the vertical part of that bar approximately coincides with the upper end of the transition zone of the silo compartment.

By one embodiment of the Invention, the ridge of the lower bar intersects with the lower vertical part of the upper bar. In this case the opposite sides of each channel formed between the cross bars and the walls of the compartment, converge, but this has as a rule no detrimental effect since the bulk material is divided and its pressure is relieved immediately thereafter. For bulk materials which are especially difficult to handle, the edge of the ridge of the lower bar may be flush with the bottom of the upper bar, becomes situated exactly below the zone in which the material is first divided and its pressure relieved.

With silo compartments of large diameter the transition zone may be subdivided into several discharge hoppers. The designing of a silo compartment with a large diameter is desirable with a view to increasing the storage capacity of the compartment without unduly increasing its height. In such case either or both bars of the divider may be duplicated so that each discharge hopper has its own cross-shaped divider,.

Several embodiments of the invention are shown, by way of example only, in the accompanying drawings. In these drawings: Pig, 1 is an axial section, along line I-I of Pig. 2, through the lower part of a silo compartment; Fig. 2 is an axial section thereof along line II-II of Pig. 1; Pig. 3 is a horizontal section along line III-III of Fig. 1; Pig. 4 is a vertical section through a silo compartment according to another embodiment taken along line IV~IV of Pig. 5; Fig. 5 is a vertical section along line V-V of Fig. 4; Pig. 6 is a horizontal section along line V -VI of Pig.. 4i Pig. 7 is a horizontal section .of a silo compartment of circular cross-sectlonj Pig. 8 is a horizontal section of a silo compartment Pig. 9 is a horizontal section of a silo compartment of octagonal cross-section; Fig. 10 is a horizontal section of a silo compartment of rectangular cross-section; Fig. 11 is a horizontal section of a silo compartment of square cross-section; Fig. 12 is a horizontal section of a silo compartment of rectangular cross-section; Fig. 13 is a horizontal section of another silo compartment of oblong-rectangular cross-section; Fig. 14 is a horizontal section of another silo compartment of oblong rectangular cross-section with two outlets; and Fig. 15 is a horizontal section of a silo compartment of circular cross-section with four outlets.

As shown in Figs., 1 to 3» a silo compartment 1 of circular cross-section comprises a conically tapering transition zone 2 between the main cylindrical part 1 of the compartment and a discharge mouthpiece 4. The latter has a rectangular opening 5 Immediately above a screw conveyor 6. The edge 9 between the cylindrical part 1 and the conical transition zone 2 is rounded.

In the transition zone 2 there is disposed a divider comprising an upper cross bar 10 and a lower cross bar 13« The upper bar comprises a flat-rectangular vertical part ID and a wedge -shaped ridge 11.. The horizontal plane dividing the ridge 11 from the vertical part 16 of the bar 10 passes through the rounded edge 9» so that the entire ridge 11 is located within the part 1 of the compartment,. The ridge 11 of bar 10 thus spans the entire width of the main part of the compartment. The lower bar 13 has similarly a flat-rectangular part and a wedge-shaped ridge 14. The latter intersects with the lower part 16 of the upper bar 10. The bottom 17 of the upper bar 10 constitutes a pressure-relieving stage for the bulk material being discharged. The same applies to the bottom 18 of the lower bar 13. In plan view (Pig. 3) the two bars of the divider partly cover the outlets 3 and 5.

This arrangement works as follows: The material is first divided by the edge of the wedge-shaped ridge 11 of the upper bar 10, and it is only slightly compressed between the inclined surfaces of this ridge and the walls of the silo compartment 1 which, in this zone, are still vertical. At the level where the tapering transition zone 2 begins, the lateral surfaces of the upper bar 10 become vertical, whereby the main direction of the pressure is changed, which prevents bridge formation. The material is only slightly compressed during its further descent between the vertical wall of the upper bar 10 and the Inclined wall of the transition zone 2. Then the material is again divided by the edge of the ridge 14 of the lower bar 13, and this division counteracts the pressurizing effect of the ridge 14. This pressurizing effect is anyhow very small because the pressure on the material is soon af erwards relieved by the step effect of the bottom face of the upper bar 10, The material now flows onwards between the vertical surfaces of the lower bar 13 and the inclined surface of the transition zone 2, so that an increase of pressure occurs only in a single direction. The bottom surface 18 of the lower bar 13 produces a step effect which - θ - ¾ The good flow properties of this discharge arrangement result from the repeated division and pressure relief of the material and the repeated change in the main direction of the pressure exerted on the material by the several parts of the silo. All these measures prevent bridges from being formed or supported.

The dash-dotted line 20 shown in Pig. 1 represents a smooth coat or lining on the inner wall surface of the silo. The upper limit 21 of the coat is sloped. In this way, any bridge that would form, would be supported asymmetrically, which in practice amounts to a prevention of this formation.

These multiple effects are achieved although the structure comprises only simple elements which do not present any constructional or statical difficulties. Instead of a screw conveyor any other discharge means may be used, if desired,, for example ,·. a chain scraper, a rotary shovel, a rotary vane cylinder or any other device.

The outlet of the square-shaped silo compartment shown in igs;†; 4 to 6 comprises a rectangular-pyramidal portion 102 and a rectangular outlet 103 fitted with a mouthpiece 104 comprising a gate 106.; The tapering transition zone 102 is built into the supporting structure of the silo compartment 101 by means of lean concrete which is provided with a suitable lining or coat,. Within the transition zone 112 the upper bar 110 of the divider is disposed.;; This has a narrow- ectangular upright part and a wedge-like ridge 111. The edge of the ridge 111 is clearly above the zone 109 where the prismatic part of the compartment merges into the pyramidal zone 102 Beneath the upper bar 110 there is disposed wedge-shaped ridge 114. The edge of the ridge 114 is flush with the bottom surface 117 of the upper bar 110. This bottom surface 117 forms a pressure-relieving step for the material. The same applies to the bottom surface 118 of the lower bar 113. The portion where the upper bar 110 and the lower bar 113 meet, forms a rectangular parallelepiped 119 which, in plan view, completely covers the small outlet 105 and the gate 106. From the fact that the upper rim of the mouthpiece 104 is slightly wider than the outlet 103, there results the formation of a further step 121 which provides for further pressure relief and enhances the step-effect of the bottom surface 118 of the bar 113.

The operation of this arrangement largely corresponds to that of the silo compartment according to Pigs. 1 to 3.

In many cases, a favourable relation between the pressure exerted on the material and the friction forces is achieved, if the height R between the edge of the wedge-like ridge 111 of the upper bar 110, on the one hand, and between the meeting point 123 and the prolongations 124 of the boundary surfaces of the tapering transition zone 102 , on the other hand, is divided into three equal sections. The upper bar 110 extends over the entire height of the upper section and the lower bar 113 extends over the entire height of the median section (see Pig. 4).

Pig. 7 is a horizontal section through a silo compartment 201 of circular cross-section comprising a circular outlet 203, an upper divider bar 210 and a lower divider bar 213., Fig. 8 shows similarly a silo compartment 301 of hexagonal cross-section comprising a hexagonal outlet 303» an upper divider bar 310 and a lower divider bar 313· Fig. 9 shows similarly a silo compartment 401 of octagonal cross-section, comprising a circular outlet 403» an upper divider bar 410 and lower divider bar 413.

Fig. 10 shows similarly a silo compartment 501 of square cross-section, comprising a square outlet 503» an upper divider bar 510 and lower divider bar 513.

Fig. 11 represents a silo compartment 601 of square cross-section, comprising a small square outlet 603» a diagonally disposed upper divider bar 610 and a diagonally disposed lower divider bar 613. - Fig..12 shows similarly a silo compartment 701 of oblong rectangular cross-section, comprising a rectangular outlet 703, an upper divider bar 710 disposed parallel to the smaller sides of the compartment and a lower divider bar 713. disposed parallel to the longer sides of the compartment,,i Fig.:, 13 shows similarly a silo compartment 801 of oblong-rectangular cross-section, comprising an oblong-rectangular outlet 803». two upper divider bars 810 disposed parallel to the smalle sides of. the compartment,L and one lower diyider bar 813 disposed parallel to the longer sides of the compartment., ' Fig.; 14 shows similarly a silo compartment 901 of oblong-irectangular cross-section.. Its discharge section is divided into two square hopperp 902 having each a square outleft 903», In order that both outlets be at least partly and one lower divider bar 913 disposed in parallel with the longer sides of the compartment.

Pig. 15 shows similarly a silo 1001 of circular cross^section. The discharge section of this compartment is divided into four hoppers 1002. Above each of the four outlets 1003 a divider is disposed. Two upper divider bars 1010 are common each to two of the hoppers, while each hopper has its own lower divider bar 1013. This arrangement is thus essentially a duplication of the arrangement of Fig,. 14. 33179/2/¾

Claims (1)

1. CLAIMS 1. A discharge arrangement for silo compartments in which a transition zone, tapering downwards in two dimensions, is interposed between the main part of the compartment and a narrower discharge mouth at the bottom of the compartment and a divider is disposed in the transition zone, characterized in that; (a) the divider is constituted by two cross bars intersecting at right angles and disposed at two different levels; (b) each cross bar comprises a main part bounded by- vertical surfaces, and a wedge-shaped ridge; (c) the ridge of the upper cross bar extends over the entire width of the compartment and its vertical surfaces are located within the transition zone; (d) the ridge of the lower bar is disposed at such a ' vertical distance from the ridge of the upper bar that the bottom surface of the upper bar constitutes a pressure-relieving stage for the bulk material on its way to the lower bar,, 2,., A discharge arrangement according to Claim 1,; wherein the ridge of the upper bar extends from the upper end of the transition zone upwards into the main part of the compartment* 3^.· A discharge arrangement according to Claims 1 or 2,, wherein the ridge of the lower bar intersects with the lower part of the upper bar, 4. A discharge arrangement according to Claims 1 or 2,,, wherein the ridge of the lower bar is flush with the bottom of the upper ba 33179/2 - 13 - 5. A discharge arrangement according to any one of Claims 1 to 4, wherein the total height of the divider is about two-thirds of the height of the discharge part of the compartment, measured from the edge of the ridge of the upper bar to the discharge opening.. 6 A discharge arrangement according to any one of Claims 1 to 5» wherein the height of the upper bar is about one-third of the height of the discharge part of the compartment, measured from the edge of the ridge of the upper bar to the discharge opening. 7,r, A discharge arrangement according to any one of Claims 1 to 6, wherein the divider extends downwards to the passage between the transition zone and the discharge mouth. 8. A discharge arrangement according to any one of Claims 1 to 7, wherein the inner wall surfaces of the transition zone and of the adjacent region of the main part of the compartment are covered with a smooth lining or coating whose upper edge is slopingly disposed in the region of the upper bar* ·! A modification of the discharge arrangement according to any one of Claims 1 to 8, wherein two upper bars are disposed in parallel and spaced from each other in conjunction with one lower barA, 10. A discharge arrangement according to Claim 9» comprising two hopper«i»llke discharge mouths located,;, respectively, beneath the crossing points of the lower bar with either upper bar. 33179/2 - 14 - 11. A discharge arrangement according to any one of Claims 1 to 8 for silo compartments having rectangular cross-sections, wherein the "bars of the divider extend in the diagonals of the rectangle. 12. A silo compartment wherein the tapering transition zone is subdivided into several hoppers having each a discharge mouth, and each hopper contains a discharge arrangement according to any one of Claims 1 to 8. RCjCB