DE1909271A1 - silo - Google Patents

Description

PATENTANWÄLTE ™ ^{/ 22 2} ° * ^Febr ' ¹⁹⁶⁹

DR.-ING. WOLFF, H. BARTELS

DR. BRANDES, DR.-ING. HuLD

STUTTGART-N, LANGE STRASSE 51 _Reg _ _{No. 12} 1

Georges Leon Henri PETIT, Paris (France)

silo

The invention relates to a silo for granular or powdery storage material with a preferably cylindrical and vertically arranged storage shaft, at least one substantially transverse to the Strut arranged along the longitudinal axis of the shaft and with a base having at least one funnel.

In order to facilitate the removal of the goods stored in the silo, a silo can with regard to its Shape, its structure and its internal geometry be improved.

A silo is essentially a container of cylindrical or prismatic shape that sits at its bottom in a funnel in the shape of an upside down truncated cone or truncated pyramid ends. The removal the content of such a silo varies according to the type of storage material, the conditions when filling and the internal geometry of the silo to a large extent. There are roughly three types of emptying differentiate the silo, namely the "wide emptying", the "column emptying" and the "funnel emptying". 1, 2 and 3 of the drawing illustrate these types of evacuation.

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When emptying the width ¹¹ (FIG. 1), the entire storage material P contained in the silo S is set in motion as soon as the mouth 0 of the funnel T is open The speed of the vertical emptying is most pronounced at the height of the funnel T. In Fig. 1, the speeds at which the storage material P moves downward are indicated at three points by arrows proportional to the length of the speed shown "Broad emptying" is to be regarded as ideal emptying, since it avoids blockages, which very often lead to clumping, and allows complete emptying of the silo. '"

The ^M width emptying "is the" columns emptying "to face. In this case (Fig. 2) is removed, only the central, vertically above the mouth 0 the hopper T arranged column of memory material, thereby forming a central passage. This is to be A real punching out of the storage material under the influence of the dividing force of gravity.If the effect of gravity is not sufficient to detach a vertical cylinder with a diameter corresponding to the diameter of the funnel mouth from the rest of the storage material, nothing moves in the silo, apart from a meniscus , which is located just above the mouth and after its emptying leaves a stable cavity initially in the form of a dome, the base of which is formed by the edge of the mouth. This type of emptying is obviously the most unfavorable Powders before, especially if this Storage good is already very colmated or very massaged. "Massaged" is an essentially hygroscopic storage material which shows a tendency to clump as soon as it has stood immobile for a sufficiently long time.

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Finally, the emptying takes place most frequently in the manner of a "funnel emptying ¹¹ (FIG. 3). In this case, a passage a is initially formed in the upper part of the storage material P contained in the silo as the starting point for emptying. When this passage reaches a certain height has surrounding him Speichergut slips along a conical surface C. by splitting off from the rest good. the opening angle oC this conical surface does not match the natural Böschungswinkeides memory good. the "hopper emptying" continues with more consecutive losses along conical surfaces C _1, C _2, C ₃ and C ₁₊ . The emptying of the silo is theoretically only complete if the opening angle / 3 of the funnel T is smaller than the opening angle <& of the conical surfaces. Otherwise (Fig. 3a) a dead store necessarily remains at the bottom of the silo M, which is never set in motion. The dead stock shown in Fig. 3a is with its minimum volume umen shown, which corresponds to the differences in the steepness of the conical surfaces ^ and the steepness of the funnel T. The presence of such a dead supply of storage material creates colmation in practice and the part of the storage material contained in the silo that is not set in motion can only increase over time. In addition, the emptying of a silo is often disturbed by the formation of cavities and stable accumulations, which occur as a result of considerable pressures at the bottom of the silo. It can be dome-shaped cavities of the type mentioned above, initially occurring cavities, be it that they occur at the beginning of emptying, or that they occur in the course of emptying after significant slipping processes occurring in the silo. They can also be hanging rings in the form of circular cavities that have accumulated at the edge of the funnel mouth and have a high degree of cohesion of their own (curvature effect).

The presence of a dead supply of storage material at the bottom of the silo is a common phenomenon. Man

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constantly observes in various branches of industry that there are dead stocks that make up 20% to 60% of the silo space. Numerous means of avoiding this phenomenon have been proposed. Just as it is generally out of the question _s to act on the retained material in order to make it "more fluid", for example by bringing it into a state of less moisture and / or reducing its ability to compress _? it is necessary to deal with the silo itself. Two basic methods can be used for the purposes mentioned. On the one hand, certain parts of the silo can be made to vibrate, in particular the hopper, and, on the other hand, a special choice can be made with regard to the geometry of the silo, in particular the shape and pitch of the with the storage goods contained in the silo from the moment of sinking on when different parts of the structure come together.

While numerous suggestions have been made regarding vibration, the geometry of the silo structure has so far insufficient attention was given, although its importance for the overall result is established.

If one considers the reasons for the formation of a dead store of stored material and of cavities in the lower part of the silo investigated «one is actually led to the effect of compression and compression on the basis of static and especially of dynamic pressures to be considered as essential. The static pressure anywhere in the The silo is the pressure exerted by the storage material due to the weight of the remaining storage material that is on it is exposed. At a certain point the static

TN, j, j TT ..- L j above, located see pressure accordingly from the height of the / Spexchergutsaule xra SxIo away. The dynamic pressure arises as a result of the free fall of the over a more or less long distance

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Storage goods from their filling into the silo. First, the storage material hits the inner wall of the funnel, then against the storage material already deposited there, which is compressed, creating a strong aftereffect .

In order to reduce the influence of the above-mentioned pressure factors, it has been proposed so far, along the descent section to arrange horizontal bars for pressure reduction of the silo. The effect of these bars is very easy. From the beginning of the filling of the silo, they divide the falling streams of storage material and reduce it thereby the compression and the dynamic pressure. "They also cut down on the emptying of the silo static pressure for the entire area of the silo shaft spanned by them. Although such bars are used to reduce pressure are known, they appear to be largely in need of improvement, both in terms of their form and their structure and their arrangement inside the silo.

The invention is based on the object of creating a silo whose emptying largely in the manner of ideal "Brexten discharge", which was defined at the outset, takes place.

Based on a silo of the type mentioned at the outset, this object is achieved according to the invention in that the one The strut that crosses the natural evacuation path has an ogival cross-section with an upturned ridge, hollow formed and its interior can be reached from the outside of the shaft. It is preferably the for Pressure reduction serving struts around prismatic hollow body, the cross-sectional contour line one from the upper ridge down has discontinuously increasing steepness and which is arranged in a radial plane with respect to the longitudinal axis of the storage shaft are, or more generally ;, in a level that is in essentially goes through the emptying axis of each hopper.

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The prismatic struts form stiffeners for the wall of the storage shaft or the funnel.

In a particular embodiment, each strut is of one elongated hood with a similar ogival cross-section superimposed, which against the fixed strut a can experience slight lowering. For example, the hood of each strut can be deformed by means of a deformable device be attached to the strut, for example by means of rubber buffers. The hood of each strut can also be fitted with an or be connected to several vibrators.

The steepness of the ogive, increasing from top to bottom Cross-section of the struts for pressure reduction results in a broken cross-section line with a sequence of Discontinuities in the incline, which promotes emptying of the silo.

_{In a special further embodiment of the silo according to the invention, a hollow tubular chimney 9} is provided along the central longitudinal axis of the silo or more generally along each vertical axis of a ^ emptying, which could give rise to the formation of a hollow column, 9 which extends essentially over the entire height of the Silo shaft extends and at its upper end preferably closed off by a hood with an ogival profile XSt ₅₁ , the steepness of the surface lines increasing from top to bottom, preferably discontinuously.

Every chimney of this type can pass through at its lower end one or more telescopic tubes adjustable in height with respect to their mouth be extended, which in the ground more or can be lowered less deeply into the funnel or funnels.

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Each chimney is preferably connected to the shaft wall by cross-shaped struts which are used for stiffening purposes. the cavities of the struts being in communication with the cavity of the chimney.

In the case of silos with large dimensions, the interior of the struts and the chimneys are provided for by personnel. There are entry openings in the underbody of the struts for observation and inspection.

In a preferred Ausführungsfor® in the form of a This silos rotatable around the central axis is provided with a central chimney, which is in front of two radially in the same horizontal plane cross-shaped struts is held.

The funnels are expediently designed so that their surface line slope is progressive and discontinuous from above increases downwards.

In the following the invention is explained in n & hand two by the drawing shown Ausführangsbeispiele of the silo according to the invention in detail. Show it :

Fig. Ί a vertical ^ central section through the first embodiment;

FIG. 5 shows a section along the line V- »V in FIG. 4; 6 shows a section along the line VI-VI in FIG. U;

7 shows a detail of a variant of the first exemplary embodiment, and

8 shows a central longitudinal section through the

lower part of the second embodiment

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The following description deals exclusively with the structure of the upper part of silos, which comprises a storage shaft and at least one funnel extending this, these parts being stationary are and do not vibrate. There can of course be further stages made of funnels, which can optionally be set in vibration be attached to the first funnel, which feed the storage material to a removal device. In addition, is always assumed that the outlet cross-section of the first funnel is expediently dimensioned so that it is as close as possible to the natural evacuation cross-section, which is generally excluded. In other words, you have to make sure that with regard to the design of the funnel profile and the Dimensions of the funnel in relation to the storage shaft no major mistake was made, see e.g. Article by A. W. Jenike, "Design your bins for free flow", published in the magazine "Modern Materials Handling" in November 1964. It then apparently seems pointless to try to improve the inner geometry of a silo without the already introduced optimum for that take into account the general profile and relative dimensions of the outlet funnel.

The first embodiment mainly shown has a arranged around a central axis AA, im substantially cylindrical storage shaft 10 and a substantially frustoconical funnel 11 as the bottom on. A removal device is located below the funnel 11 12, which is supplied via a possibly vibrating funnel 13 which causes a pressure reduction can be.

According to the technical teachings of the invention, a central tubular chimney m is arranged in the axis AA and held at its upper end by a preferably removable hood 15 with an ogival shape Profile is complete.

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Of the? Chimney If with the »hood 15 is made by two pairs of See crossing, hollow struts with a prismatic cross-section held at two different heights, the Struts 2Θ and 21 are arranged above the struts 30 and 31,

The struts 20 and 21, which are inside the chimney 14 would cross, thus serve as stiffeners for the entire structure of the silo. They are hollow and their interior is accessible to personnel in the case of large-sized silos. For this case are in the sub-floors 20a, 21a, 30a and 31a of the struts 20 or 21 or 30 or 31 openings 20b or 21b or 30b or 31b are provided for an inspection of the interior of the silo, as FIG. 6 shows. Thanks to these openings, which are preferably covered with grids, which themselves have dust-tight flaps can be covered, one can see the state of removal observe the storage goods contained in the silo and as soon as when the beginning of colmation or a cavity is detected or discovered, the necessary countermeasures grab, for example by causing the funnel 13 to vibrate.

This new possibility allows this technology to be used rapidly To make progress thanks to the industrial "large-scale" and observations and measurements made on silos made of normal building materials (various parameters such as degree of emptying, Pressure, speed, etc.), while until now one has been forced to use scaled-down models, the were made of transparent materials with completely different properties, which diminished the value of the experiments became.

The use of hollow struts according to the invention opens up In addition, very interesting possibilities: Man.can

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19D9271

control and monitor the inner state and b which deteriorates through wear and tear, and one restore favorable conditions inside the struts, by regulating the air circulation there. In particular? the interior of the struts can be heated, which can be achieved with low Cost is associated and a warming of the struts neighboring storage goods. This latter possibility is very interesting because In this way, lasting ripeness .on Speiehergut.with can avoid high moisture content.

An essential feature can also be seen in the fact that hoods, for example the hood 15, struts, for example the strut 21, and funnels, for example the funnel 11, have a wall whose cross or longitudinal section is progressive and discontinuous from top to bottom has increasing steepness of the outline. The cuts through the elements mentioned therefore follow kinked lines 0, B, C, D or O ¹ , B », C ¹ , D ¹ or _: 0", B ", C" ₉ D ". It has been shown experimentally that the downward increasing slope facilitates the emptying of the storage material and that the discontinuous. lent increasing steepness represents an optimum. Caused a discontinuous increase in slope. thanks to their propulsive effect to a much lesser extent a sticking of stored goods than a con. continuous increase in slope. For example, the slope can be discontinuous but uniform by χ degrees. : increase per unit of decrease in height. > .. _; ^; \

A large number of advantages are achieved with the first exemplary embodiment according to FIGS. 4, 5 and 6 '. First of all, the presence of the tubular central chimney Vt _9, which at its upper end is closed off by the hood 15 ', prevents the formation of a preferred central outlet at the time of removal of storage material -' from the silo.

0098 34 / T T5 7 ", .- ■ :.>

emptying. The storage material can only sink in the annular space between the chimney and the shaft wall. Therefore, the entire storage material will be moved while the silo is being emptied. A3.so you forcibly mobilized those zones in Speichergut which tend to persist. In addition, causes in the case of a loading of the silo, which takes place by introducing storage material in the direction of arrow F (Fig. 5), the presence of the hood 15 that the initiated stream of the storage material is zer divides, so that in this way when filling the Dynamic pressures generated by silos are reduced.

The struts 20, 21, 30 and 31 for pressure reduction play an analogous role as far as the dynamic pressures are concerned. In addition, due to their distribution in height, they also contribute to a reduction in the static pressures in the silo.

Although in the first embodiment according to FIGS. 4, 5 and 6, the struts 20 and 21 on the one hand and the struts 30 and 31 on the other hand, which are arranged at different heights, have been shown so that the struts 21 and 31 on the one hand and the struts 20 and 30, on the other hand, are each arranged in a common plane passing through the axis AA , the struts could also be arranged in different planes so that adjacent planes enclose an angle of 45 degrees between them. The two struts at a certain height would then be arranged, for example, in planes XX, while the other two struts would be arranged at a different height in planes YY, as FIG. 6 illustrates.

From Fig. 5 an interesting variant of the embodiment can be seen. Here the central tubular chimney 1 can be extended downwards into the funnel 11 and possibly into the vibrating funnel 13. This can be done with the help of an extendable telescopic tube 40,

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and 42 accomplish that in the extended state in Fig. 5 is shown in dashed lines. With such a telescopic tube, the height of the mouth opening can be adjusted even while the silo is in use. You can therefore adjust the telescopic tube while emptying is in progress. This very essential telescopic tube allows the length of the central chimney to be adapted to the species of the goods stored in the silo. A further embodiment can take place, for example, in the following ways:

a) You can join the individual tubes with elastic connections, which eliminates any self asymmetrical snagging allowed (connection by spiral springs, other elastic elements or "

™ damping blocks with a "limitation of the stroke" Attacks).

b) To improve self-elimination, one can

the outside of the pipe or the outside of the pipes or cover the inside of the last funnel with coverings, if necessary in an asymmetrical way, which give a very different coefficient of friction.

c) The lowest tube U2 can be connected to a vibrator be in order to facilitate the removal of the storage goods in the vicinity of the narrowest passage cross-section and

fc to add the measures according to a) and b). .

In the first example, each strut is, likewise ' like the final hood 15, for example the strut 31, lined at its apex by a support 50 with a V-shaped cross-section, the apex edge pointing downwards shows. For the struts, this support consists of a metal angle bar. On such an edition heaps the storage material falling in the shaft attaches itself to it and quickly creates a wear-free point or a wear-and-tear loose ridge at the vertex of the overlay Part.

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With one !? Another developed variant of the first embodiment is, as shown in FIG. 7 shows, a ^{strut designated overall by SO 1} is provided, which has a base body 51 on which an elongated, roof-like hood 52 is attached. The hood 52 is fastened to the base body 51 corresponding to the previous struts by means of elastically deformable connecting pieces, namely by means of rubber buffers 53. In this way, the hood 53 can be moved relative to the base body 51 when it is subjected to vertical or inclined pressures. Such a structure avoids undesirable accumulations and deposits and thus serves the same purpose as the profile of the hood with its steepness increasing downwards / Furthermore, a vibrator 54 is provided which can set the hood 52 in vibration. It should be noted here that different variants like this are only possible thanks to the inventive measure, which consists in the use of hollow struts that can be reached from the outside.

It should also be noted that the pressure reducing struts and / or axial tubular chimneys can be used in all types of silos. A chimney will expediently be placed there where otherwise the formation of a preferred evacuation path is to be feared. The strivings become systematic used to reduce static and dynamic pressures. In the case of a silo with a cylindrical shaft of For example, you will only get low at a certain height Use struts that cross each other at a height, while silos with a greater height use at least two different Heights struts will attach.

Finally, FIG. 8 shows a second embodiment in the form of a high silo according to the invention, which has three funnel mouths S ₁ , S ₀ and S «. In this case, the emptying flows of storage material against the funnel mouths S ₁ , S ₂ and S _{3 are} to

0098 3 4/1 1 5? _t κ - ^. _{ϋ ν} .

ORiGfNAL INSPECTED

steer and avoid excessive increase in 4 static yngt to avoid dynamic pressures, various struts 79, 80, 81, 82 vertically above the funnel openings * arranges which partly run parallel to one another, cross each other. The second example should be? to Veransehaulichung the realization of the invention serve a non-circular silo *, - -: - ·

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■ vn, € ν ν ,, -. ORIGINAL »NSPEUifc

Claims (13)

- 15 claims: 1.! Silo for granular or powdery storage goods with one preferably cylindrical and vertically arranged storage shaft, at least one essentially transversely strut arranged to the longitudinal axis of the shaft and with a bottom having at least one funnel, thereby characterized in that the strut traversing a natural evacuation path has an ogival cross-section with the ridge turned upwards, is hollow and its interior can be reached from the outside of the shaft is. 2. Silo according to claim 1, characterized in that the outline of the cross section of each strut (20, 21, 30, 31; 80, 81, 82) is discontinuous from the upper ridge downwards has increasing steepness. 3. Silo according to claim 1 or 2, characterized in that at least one group of two cross-shaped in the same Struts arranged horizontally (20, 21; 3O, 31) are provided. · »« Silo according to claim 3, characterized in that the crossing struts (30,31) are arranged at the lower end of the shaft (10) above the floor (11). 5. Silo according to one of claims 1 to 4, characterized in that that each strut (51) of a vibratable, preferably a similar cross-section having hood (52) is shielded upwards. 6. Silo according to one of claims 1 to 5, characterized in that that a central, tubular chimney aligned with the mouth of the funnel in the direction of emptying is provided by at least one, two spokes 009834/1157 forming strut (20,21; 30,31) between KajKinwandung and shaft wall is held. 7. Silo according to claim 6, characterized in that the chimney (IU) is connected to the shaft wall by a group of two cross-shaped struts (2O, 2i; 3O> 3i) ^: £ n two horizontal levels at different heights. 8. Silo according to claim 7, characterized in that. that the two groups of struts (20.21; 30.31) azimuthally are twisted against each other, preferably by 45 * 9. Silo according to one of claims 6 to 8, characterized in that the chimney (14) at its upper end facing away from the bottom (11) is closed by a hood (IS) ⁵ with an ogival profile, the steepness of the surface lines from above increases downwards. 10. Silo according to one of claims 6 to 9, characterized in that the cavities of the struts (20, 21; 30, 31) communicate with the cavity of the chimney ClMi) ;. 11. Silo according to one of claims 6 to 10, characterized in that that the chimney (14) at its lower end durci * W a telescopic tube (40, 41, 42) adjustable in height with respect to its mouth is extended and can be lowered into the floor CIl). 12. Silo according to claim 11, characterized in that the telescopic tube (40,41,42) at least partially in Vibration is displaceable. 13. Silo according to claim 12, characterized in that the lowermost pipe part (42) can be set in vibration 009834 / ttSf IH. Silo according to one of Claims 1 to 13, characterized in that the bottom forms a funnel (11), whose surface line gradient increases progressively and discontinuously from top to bottom and whose mouth cross-section corresponds to a natural emptying cross-section. 009834/1157