DE19521870A1 - Round, large silo funnel-shaped discharge - Google Patents

Abstract

The discharge comprises several asymmetrical funnels below a round, main silo chamber, whose top edges (1) lie on one plane. The peripheral, outer supports (4) of the funnels are located on the silo inner wall in the manner of a chord. At least three walls of a funnel are so steeply inclined that the boundary angle for a mass flow is maintained, or not fully reached. At the floor the funnels contain a slotted discharge aperture, behind which are incorporated controllable and tightly closable silo discharge mechanisms.

Description

The invention relates to a silo discharge for preferably round large silos with funnel-shaped discharge for fine-grained to powdery cohesive bulk goods.

In particular, very fine cements or for time setting inclined fly ash from power plant technology, but also FGD gypsum, chalk, hydrated lime or dried sewage sludge me can not or only with considerable difficulty are discharged from pneumatic silo systems. Out for this reason there have been more or less in recent years complicated mechanical silo discharge devices been introduced

In principle, you can choose between the "first in - last out" and the "first in - first out" principle.

The first principle is used in solutions in which lifting and lowerable rotating scratches or snails from the Convey the silo blanket from the bulk material to the center. From the The goods are transported to the center via chutes (DE 32 33 742, DE 29 02 484, cement lime gypsum 36 (1983) No. 5, Pp. 266-267) or about an emerging core flow shaft in the gravitational flow at the bottom, e.g. B. about a Tilt beam discharge, deducted. (Processing technology (1978) No. 11, pp. 536-540).

On the one hand, these solutions are very complex in terms of equipment and on the other hand have the decisive disadvantage that the goods stored first are discharged last. For Goods that tend to solidify, such as B. Flight ash, cement, FGD gypsum etc., it means that the silos have to be emptied at certain intervals.  

Otherwise, solidifications cannot be controlled come on the silo floor.

The second principle is in the case of discharge at the bottom advise such as clearing wheels (DE 32 60 727, DE 33 42 099), rotier End screws (DE 27 47 564, DE 31 46 611) applied. These discharge devices are difficult to access and are not available against a very large silo pressure, so that they are robust must be structured and have high drive power sen. Another disadvantage is the high wear and tear due to the movement of the conveyor units under the high Silo printing.

So-called teat bunkers are also state of the art known with several metal funnels on the silo floor. These Kind of silos has been used for free flowing, iced over bulk goods such as raw coal or cement clinker turns. The advantage of these silos is that the bulk material pressure on the actual discharge device, e.g. B. a swing funnel or discharge belt due to the pressure reduction in the convergent funnel is relatively small and that the Extractors are easy to maintain from the outside. For powdered These simple funnels can be used for cohesive, highly cohesive goods not be used because the necessary cross-trigger cut against bridging, possibly several Square meter, is not reachable or in case of a through shooting of the goods cannot be sealed due to fluidization is. The steep trich necessary for a mass flow are with a concentric deduction from the Funnel, e.g. B. by rotary valve or Schwingför but not because of the very large height required reachable. With the so-called "flat deduction from long slit-shaped openings, e.g. B. with heavy trigger belts the funnel can be flatter (see Schwe des: Flow behavior of bulk goods in bunkers, publisher Chemistry, Weinheim / Bergstrasse, 1968), but hardly stand Devices are available that have an even deduction enable the entire slot cross-section.

The invention is based, for large Silos in which very cohesive goods are stored, one mechanical discharge device to create a simple, inexpensive and uncomplicated construction and a complete emptying of the silo under Avoiding the above Disadvantages of the known solutions enables.

This object is achieved with the features of Claim 1 solved. Advantageous embodiments of the Invention are specified in the subclaims.

The device according to the invention provides that below large, preferably round silos two or more Sheet metal or concrete funnels are arranged so that the The top edges of the funnels lie in one plane. At least two of the hopper edges on the silo circumference are like this arranged to cut the inner wall of the silo like tendons the. The funnels have wide and long slits discharge openings that have a length-width ratio nis of at least 2.0 and with adjustable and tightly closing silo extraction devices, such as. B. Tilt bar discharge devices are provided. At least three of the funnel walls are inclined so steeply that the Limit angle for mass flow observed or undershot will.

By arranging several silo discharge hoppers and the steeply placed funnel walls on the one hand a good emptying of the silo with relatively little high height guaranteed. Bridge formations are ver avoid and a residual emptying of the silo is given. On the other hand, the slit-shaped discharge opening seals with simple pull-off devices controlled material deduction over the entire Slot outlet is possible without any problems.

The invention is illustrated by means of exemplary embodiments  explained. In the accompanying drawings:

Fig. 1 shows a cross-section of the silo,

Fig. 2 shows the section AA of FIG. 1.

The round large-capacity silo for in particular fine-grained to powdery cohesive bulk material is arranged below four funnels 2 in such a way that the upper edges 1 of the funnels 2 lie in one plane. The arrangement of the upper edges 1 in a plane of the bottom provided funnel 2 enables the introduction of a load-bearing truss structure 3 , the distance between the funnel edge and the silo inner wall should be as small as possible to avoid dead zones. This small distance is achieved by the tendon-shaped introduction of the outer carrier 4 . This results in an asymmetrical trich terform.

For the even flow of bulk material from slit-shaped openings, the hopper inclination angle α of the funnel walls for mineral materials in connection with sheet steel running parallel to the long slot side may only be approx. 17 to 26 °. The exact angle can only be determined after the measurement of the wall friction angle ϕ _w between the bulk material and the wall material and results from the known design process for mass flow silos according to Jenike (Jenike, AW: Storage and flow of solids ", Bull. 123, Univ Utah, Salt Lake City, 1964).

However, this small angle can only be achieved with reasonable effort if several funnels 2 are provided and if the width of the slot outlet is as large as possible. The length-width ratio should be at least 2.0.

The end wall 5 is almost vertical or very steep. Exceeding the limit angle α is accepted at most on one funnel wall, so that mass flow (wall sliding) nevertheless occurs on the other wall and no so-called core flow funnel can form in the main silo room. A core flow means that the bulk material does not slide on the wall. The consequences are irregular flow, caking and the increased risk of bridging.

The inventive design of the silo discharge light almost 100% residual emptying when the remaining horizontal surfaces 6 are chamfered in the main silo room.

As a discharge device, for example, a tilting beam discharge 7 or a long cell wheel lock (not shown) with one or two cell wheels or a screw conveyor with a progressive gradient can be used. These devices are evenly distributed over the entire slot cross-section, are easy to regulate and close tightly. The further transport can be carried out by conveyor belts of 8 or any other transport devices. The tilting beam discharge 7 enables very large slot widths and is therefore particularly suitable.

Reference list

1 top edge
2 funnels
3 truss construction
4 outer straps
5 end wall
6 horizontal surface
7 Tilt beam discharge
8 conveyor belt
α funnel inclination angle

Claims (6)

1. Silo discharge for preferably round large-capacity silos with funnel-shaped discharge for fine-grained to powdery ge cohesive bulk goods, characterized in that two or more asymmetrically designed funnels ( 2 ) are arranged below a round main silo space, the upper edges ( 1 ) of which lie in one plane which outer supports ( 4 ) of the funnels ( 2 ) lying on the inner circumference of the silo are arranged in a sinew shape on the inner wall of the silo, so that at least three walls of a funnel ( 2 ) are inclined so steeply that the critical angle for mass flow is maintained or undercut and the funnels ( 2 ) have a slot-shaped discharge opening on the bottom, which is followed by adjustable and tightly closing silo extraction devices. 2. Silo discharge according to claim 1, characterized in that the length-width ratio of the slot-shaped discharge openings of the funnel ( 2 ) is greater than 2.0. 3. Silo discharge according to claim 1 and 2, characterized in that the funnel ( 2 ) on a truss construction ( 3 ) are suspended. 4. silo discharge according to claim 1 to 3, characterized in that the horizontal surfaces ( 6 ) in the main silo are chamfered. 5. Silo discharge according to claim 1 to 4, characterized in that the silo extraction device is designed as a tilting beam discharge device ( 7 ). 6. silo discharge according to claim 1 to 4, characterized in that the silo extraction device as a cellular wheel lock with one or two cellular wheels or snails with a progressive gradient in the conveying direction or several parallel screws is formed.