FR2841544A1 - SILO DRAINING DEVICE - Google Patents

Abstract

Silo emptying device comprising tunnels (1), into which air is sent, formed from concrete elements (2) resting on the bottom of the silo and providing between them buckets (4) communicating with said tunnels by openings characterized in that each opening is formed by the cooperation of a notch (6), formed on the lower field of the element, and by the bottom of the silo, each opening forming a corridor favoring the inversion of the direction of propagation of the air flow.

Description

i The present invention relates to improvements to

  emptying devices for flat bottom silos containing granular products.

  The known devices, although very different, use common means, namely tunnels, resting on the bottom of the silo, into which air is sent. The air comes out of the tunnels through the openings provided in the latter and pushes the product to be drained, contained in the buckets formed by the bottom of the silo and the tunnels, towards an evacuation device. It should be noted that the product is pushed into the

  buckets in the opposite direction to that of air circulation in the tunnels.

  Generally, tunnels are formed by metal ribs made from corrugated and curved sheets, in which it has been

  made, by cutting, gills for the air outlet.

  One difficulty encountered consisted in preventing the penetration of the

produced in tunnels.

  A first solution consisted in making openings of a width less than the average diameter of the grains, but as a silo can receive very different products (wheat or but for example), it was necessary to adjust the width of the gills to that compatible with the finest product. This solution is not entirely satisfactory because, to compensate for the pressure drop, it was necessary to increase the power of the blower with all the disadvantages that

this presents.

  A second solution, illustrated by European patent N0 240386, consisted in providing a means, inside each tunnel, to prevent the penetration of the product, namely: a plate extending behind the gills and whose height is greater to that of the latter. This solution is not entirely satisfactory because, in addition to complicating the implementation, it

disrupts the flow.

  In general, these devices, comprising thin structures which tend to deform, are not suitable for use in large silos. It should also be noted that the metal tunnels do not lend themselves well to obtaining a good seal at the level of the

concrete floor.

  Part of the above problems found a solution both in the device described in the French patent application No 00 1 5858 filed on 7/1 2/2000, in the name of the applicant and in the French patent N0

2720055.

  An essential contribution of the request 00 1 5858 consisted in making the tunnels from concrete elements having laterally large openings closed by plates comprising air outlet openings

  opposing the penetration of the product inside the tunnel.

  In the French patent N0 2720055, a composite tunnel is described, comprising a metallic structure in the shape of a vote, resting on longitudinal shims having oblique recesses or openings the cross section of which is much greater than the mean diameter of the grains of the product to

thin.

  According to this device, it seems obvious to give the width of each block a dimension greater than tgX / h (expression in which "X" is the angle of the slope of slope and "h" the height of the opening) of way to

  oppose the penetration of the product into the tunnel.

  However, this device has two major drawbacks.

  Being a composite product, it is expensive and poorly withstands loads. In addition, the axis of each opening forms with the direction of the air flow in the tunnels an angle less than 60. Experience has shown that it is very difficult for air to pass through the openings, especially those located

  near the distribution duct (those located near the entrance to the tunnels).

  In fact, in these zones, the speed of the air flow is high and no means are provided to allow this flow to suddenly change direction. It appears from the above explanations that none of the known devices is capable, on its own, of solving all the problems raised by the

emptying of a silo.

  The device of the invention, which uses concrete elements with large lateral openings to make the tunnels, is remarkable in that the openings open onto the lower field of the element and are configured to favor the reversal of the direction of

propagation of the air flow.

  The invention also provides for the use of composite elements, a metal part of which is produced in the factory, the completion of the element being

  carried out on site by the sprayed concrete technique.

  The invention will be better understood from the description which follows given in

  referring to the attached drawing by way of indicative example only, in which: FIG. 1 is a view in vertical section of the bottom of a silo comprising the elements of the invention; FIG 2 is the bottom view of the elements of Figure 1; FIG. 3 is a view, on a larger scale, of detail A in FIG. 2;

  FIG. 4 is the "left view of FIG. 3.

  FIG. 5 is a view in vertical section showing the blank of a composite element; FIG 6 is a view similar to that 5, showing the completed element; FIG. 7 is a partial view showing, from below,

the element of figure 6.

  Referring to FIG. 1, it can be seen that the tunnels 1, into which air is sent, are formed from elements 2, made of concrete, judiciously abutted resting on the bottom 3 of the silo. In known manner, the elements 2 provide between them a space, or bucket 4, in which the product to be drained collapses. On at least one of the lower fields 5 of each element, notches 6 have been made opening out laterally. These notches form, in combination with the bottom 3, a corridor allowing the air sent into the

  tunnels to stand out in the buckets 4.

  These corridors are shaped so as to favor the reversal of the direction of

  propagation of the air flow (direction Fi in the tunnels and F2 in the buckets).

  As can be seen, in particular, from FIG. 3, each notch has a portion 6a, substantially rectilinear, forming an acute angle with the direction Fi, continuing with a portion 6b, substantially circular which is connected to a portion 6c, substantially rectilinear , forming an acute angle with the direction F2. The element which has just been described above is produced in the factory and, in certain cases (renovation of existing silos), it can cause problems during

of its implementation.

  According to another characteristic of the invention, a composite element is used, part of which is produced in the factory, the completion of the element

  performed on site using the sprayed concrete technique.

  As can be seen from FIG. 5, a blank 7 is produced in the factory, in folded sheet, reproducing the lower contour of the element. This blank has, on at least one of its lower fields, a plurality of flaps 8, the latter being arranged on the field and being shaped so as to

  channel the air as described for the notches 6.

  After placing the blanks on the bottom of the silo, we complete the construction of the corridors using the sprayed concrete technique, the blanks acting as lower formwork. We stop spraying the concrete as soon as

  the elements have the profile shown in Figure 6 for example.

  It should be noted that this technique makes it possible to solve all the sealing problems between the butted elements and between the elements.

extremes and the silo walls.

  The blanks can be reinforced by a lattice reinforcement 9,

  set up in the factory or prior to spraying the concrete.

Claims (4)

  1 - Silo emptying device comprising tunnels (1), into which air is sent, 'formed from concrete elements (2) resting on the bottom (3) of the silo and providing between them buckets (4) communicating with said tunnels by openings characterized in that each opening is formed by the cooperation of a notch (6), formed on at least one of the lower fields of the element, and by the bottom of the silo, each opening forming a corridor favoring the reversal of the direction of propagation of the air flow.   2-Device according to claim 1, characterized in that each notch has three portions (6a, 6b, 6c), namely two substantially straight portions (6a, 6c) connecting to each other through a portion (6b ), substantially circular, each end portion forming an acute angle, respectively, with the direction of the air circulating in the tunnel   and with that of the air circulating in the corresponding bucket.   3-Device according to claim 1, characterized in that composite elements are used, part of which (7), produced in the factory, reproduces the profile of the lower part of the element which is completed, after placement of the   sketches on the bottom of the silo, using the sprayed concrete technique.   4-Device according to any one of claims 1 to 3, characterized in that each tunnel communicates with the corresponding trough by a single opening, formed by the lower field of the element and the bottom of the silo, extending over its entire length and comprising flaps (8), arranged on the field and profiled so as to favor the reversal of the direction of propagation of the air flow.