EP0828126B1 - Ventilation apparatus for drying products,especially freshly formed products to be cured afterwards - Google Patents

Abstract

The ventilator is mounted at the upper end of a casing to drive an air flow parallel to the axis of the casing. The outlet opening (33) for the air flow is disposed obliquely with respect to the axis of the casing. The outlet opening can have multiple blades (34) fixed to a plate (36) situated in a plane parallel to that containing the outlet opening so that the flow of air is deflected in a horizontal direction perpendicular to the rows of stacks of product to be dried. The axis of the casing can form an angle 'a' of between twenty and forty degrees with the plane containing the outlet opening.

Description

The present invention relates to a ventilation device for drying of stacked products according to the preamble of claim 1. Such a device is known from EP-A-0 017 665. It is more particularly intended for industry ceramic and for example the drying of raw products in the ground before their passage in a baking oven.

It is known to have stacks of raw products (bricks or tiles for example) from a molding workshop in a dryer. These stacks are arranged in parallel rows separated by corridors in which move fans that blow hot, dry air onto these stacks.

In the known devices, two types of device are used. ventilation: vertical or horizontal axis, which either have an energy efficiency insufficient or require a plurality of fans.

In French Patent No. 699,030 for example, there are above each stack a fan with a horizontal axis, which is placed in a box which deflects the air flow at 90 ° to direct it vertically downwards, after which this air flow is again deflected by fins to enter the stack. This double deviation of the air flow causes a very significant loss of energy.

In the French patent of addition 22,590 a rolling box has been described in which the air flow is introduced vertically from top to bottom to be then diverted a first time to become horizontal, after which it is deflected again by fins to be directed obliquely upwards. There also this double deviation absorbs a very large amount of energy.

In patent EP 0.017 665, a box is placed between the stacks. the walls converge slightly downward, provided at its upper part with a plurality fan, the walls having side slots. This box is placed under pressure by the fans and the air thus pressurized escapes through the slots side. Such pressurization of the air absorbs a lot of energy.

In patent GB 2,039,013, a device has been described consisting of a conical rotary sheath, provided with longitudinal slots. This device has the same disadvantages than that of the previous patent EP 0.017.665 to which is added the fact that the distance between the slit and the products to be dried varies continuously which harms homogeneity of drying.

The present invention relates to a ventilation device which has good better performance than known devices.

The present invention relates to a ventilation device for drying stacked products of the type comprising a box provided on the one hand with a fan and on the other hand, outlet openings, the fan being arranged at the end of said box to propel an air flow characterized by the fact that the axis of the ventilation flow makes with the plane containing the outlet opening an angle "a" such that this opening cuts totally fan flow.

a/ l'ouverture de sortie est munie d'une pluralité de lamelles fixées à une plaque située dans un plan parallèle à celui contenant l'ouverture de sorte que le flux d'air soit dévié dans des directions horizontales pratiquement perpendiculaires aux rangées d'empilages de produits à sécher.

b/ l'axe du caisson fait avec le plan contenant l'ouverture de sortie un angle compris entre 20° et 40° et de préférence égal à 30°;

c/ les dimensions du caisson et la valeur de l'angle sont déterminées de façon telle que la hauteur de l'ouverture soit sensiblement égale à la hauteur des empilages de produits à sécher;

d/ l'ouverture de sortie du caisson est verticale, l'axe dudit caisson étant oblique;

e/ l'axe du caisson est vertical, le plan contenant l'ouverture du caisson étant oblique;

f/ le caisson est un cylindre et l'ouverture est ovale.

g/ le caisson est parallélépipédique et l'ouverture est rectangulaire.

This device is still remarkable in that:

a / the outlet opening is provided with a plurality of strips fixed to a plate situated in a plane parallel to that containing the opening so that the air flow is deflected in horizontal directions practically perpendicular to the rows of stacks of products to be dried.

b / the axis of the box made with the plane containing the outlet opening at an angle between 20 ° and 40 ° and preferably equal to 30 °;

c / the dimensions of the box and the value of the angle are determined so that the height of the opening is substantially equal to the height of the stacks of products to be dried;

d / the outlet opening of the box is vertical, the axis of said box being oblique;

e / the axis of the box is vertical, the plane containing the opening of the box being oblique;

f / the box is a cylinder and the opening is oval.

g / the box is rectangular and the opening is rectangular.

The invention also relates to a drying enclosure comprising, between the rows of products to be dried in the corridors in which circulation devices circulate ventilation according to the present invention.

By way of example and to facilitate understanding of the invention, we have shown in the accompanying drawings.

Figure 1: a front view and in section along AA of a device for ventilation with known vertical axis.

Figure 2: three views in side elevation, from behind and in plan of a ventilation device with horizontal axis of known type.

Figure 3: a side elevational view of an axis ventilation device oblique according to the invention

Figure 4: a front view of the ventilation device in Figure 3.

Figure 5: a partial perspective view of the ventilation device Figures 3 and 4.

Figure 6: a top view of the ventilation device of Figures 3 to 5.

Figure 7: a side elevational view of an alternative embodiment of the invention.

Figures 1 and 2 show two ventilation devices of known type; FIG. 1 representing a device with a vertical axis and FIG. 2 a device with a axis horizontal.

In Figures la and 1b we see that the device consists of a cylinder 10, with a vertical axis, surmounted by a fan 11, driven by a motor 12 and comprising two lateral openings 13 and 14 located along two generators diametrically opposite

The air, sucked in by the fan it enters through the opening 15, descends vertically in cylinder 10 in which it is pressurized so that it exits laterally through the openings 13 and 14, being directed perpendicular to the stacks A of raw products B.

This device has two drawbacks. The first is that the air flow entering the cylinder through the opening 15 causes a venturi effect which has for result that there is no blown air on the stacks at the top of the cylinder (about 50 cm) but on the contrary a slight aspiration. Products B located at upper part of the A stacks are therefore poorly dried. The second drawback is that the enclosure of the cylinder 10 must be pressurized so that the air is blown horizontally through the longitudinal slots 13 and 14. This necessary pressurization constitutes a loss of energy so that the efficiency of the device in is affected.

To avoid these two drawbacks, the device shown in Figures 2a and 2c.

The ventilation device comprises a box 20 which comprises two side openings 24, opposite, extending over the entire height of said box 20. A plurality of fans 21 are arranged one above the other over the entire height and are arranged to blow the drying air in one direction represented by the arrow fl. This air flow is deflected 90 ° on one side and 90 ° on the other by covers 23 which divide the air flow into two opposite streams f2 which arrive at the openings 24.

This device has the advantage of eliminating the two drawbacks of the device of Figure 1 but has the disadvantage of requiring a large number of fans 21, each driven by a motor 22 and therefore to be expensive, more the 90 ° deflection of the air flow causes energy loss.

The present invention relates to a ventilation device having neither the drawbacks of the device of FIG. 1 nor that of FIG. 2.

This device consists of a box 30 provided at its upper part a circular opening 35 in which is placed a fan 31 driven by a motor 32, and the outlet opening 33 of said box 30 is in a plane which is oblique to the X axis of the box which is also the axis of the air flow.

In the example shown in Figures 3 to 6 the X axis of the air flow is oblique and the outlet opening 33 of the box 30 is in a vertical plane.

Referring to Figures 3 to 6 we see that the box 30 is a rectangular parallelepiped of which the X axis is arranged obliquely, and the fan 31 is placed in the casing 30 so that the axis of the air flow which it causes coincides with the X axis of the box.

The section of the parallelepiped 30 by a vertical plane is a rectangle 33 whose short side is equal to the side of the square section of the box 30; the angle "a" that makes the X axis with said vertical plane is determined so that the long side of said rectangle 33 has a length substantially equal to the height "h" of the stacks A.

In the example shown, this angle "a" is approximately 30 °. In practice it must be between 20 ° and 40 ° but whatever the value of this angle "a", it is such that the outlet opening 33 completely cuts off the flow of the fan 31.

On this opening of the box 30 which constitutes the rectangle 33 we have a plurality of strips 34 connected to a vertical plate 36, parallel to the opening 33.

• que le flux d'air de séchage est efficace sur toute la hauteur des empilages A;
• qu'il n'y a pas ou pratiquement pas de perte d'énergie par mise en pression du flux d'air;
• qu'un seul ventilateur par caisson est nécessaire.

It follows that the air flow sucked by the fan 32, descends into the box according to the arrow F1, parallel to the axis X, then is deflected by the blades 34 so as to exit horizontally according to the arrows F2 and this on the entire height of the opening 33 therefore over the entire height "h", the arrows F2 being parallel to the vertical plane containing the plate 36 (see FIG. 5). The result is:

• that the drying air flow is effective over the entire height of the stacks A;
• that there is no or practically no loss of energy by pressurizing the air flow;
• only one fan per case is required.

All these advantages have the effect that this ventilation device has a better energy efficiency and lower production cost than the devices known prior.

Preferably, as shown in Figures 4 to 6, the enclosure of drying 40 comprises several pairs C of rows of stackings A between which are created in corridors D. In the example shown in Figure 6 there are two pairs C of rows of stacks and three aisles D. A plurality of ventilation devices E are move in corridors D, each ventilation device E being in accordance with device described in Figures 3 to 5.

It should be noted that in the example shown the box 30 has a section square slightly larger than the diameter of the fan 31, this arrangement being geometrically the most convenient. But it is obvious that to adapt the box air distribution constituted by the opening 33, the slats and the plate 36 can adapt the dimensions of the rectangular parallelepiped constituting the box 30; the invention being in no way limited to the embodiment chosen.

Comparative tests were carried out between a caisson device cylindrical with vertical axis, like the box 10 in FIG. 1 and a box oblique axis parallelepiped, like the box 30 of figure 3 to 6, both being housed with the same fan driven by the same motor, the speed of the air drawn into the box being 15 m / sec.

In the box 10 the static pressure was 25 mmCE while in the box 30 it was 12 mmCE.

In the box 10 the air flow leaving through the orifices 13 and 14 was partly high oriented at about 45 ° obliquely downwards, this obliquity decreasing gradually to be practically zero at about 50 cm from the entrance of the box, but the speed of the flow was very low at the top so as not to reach its maximum at the base of the box.

This shows that the ventilation of a stack is only really correct in lower part.

By cons with the box 30 and the formwork 34/36 we obtain not only less energy loss (lower pressurization) but perfect distribution of the air streams according to arrow F2 all horizontal and at the same speed.

On the other hand the invention is not limited to the case where the box 30 is a rectangular or square section. This box can indeed be a cylinder whose directrix can be a circle where an ellipse in this case the opening 33 is an ellipse and the dimensions of cylinder 30 and the value of angle "a" must be determined so that the major axis of the ellipse is practically equal to "h".

Figure 7 shows an alternative embodiment which is in fact the second possible alternative embodiment of the invention: in the first case (Figures 3 to 6) the X axis is oblique and the opening 33 vertical; in the second case (figure 7) the X axis is vertical and the opening 33 oblique. Apart from that all the elements are the same and carry therefore the same references.

Claims (8)

1. A ventilation device for drying stacked products, of the type comprising a box structure (30) provided firstly with a fan (31) and secondly with outlet openings (33), the fan being arranged at the end of said box structure in order to impel an air flow therein, characterised by the fact that the axis (X) of the ventilation flow forms an angle "a" with the plane containing the outlet opening (33) such that said opening completely cuts off the flow of the fan.
2. A ventilation device according to Claim 1, in which the outlet opening (33) is provided with a plurality of blades (34) fixed to a plate (36) which is located in a plane parallel to the one containing the opening (33) such that the air flow is deflected into horizontal directions (F2) which are practically perpendicular to the rows of stacks (a) of products to be dried.
3. A device according to Claim 2, in which the dimensions of the box structure (30) and the value of the angle "a" are determined such that the height (H) of the opening (33) is substantially equal to the height (h) of the stacks (A) of products to be dried.
4. A device according to any one of Claims 1 to 3 in which the outlet opening (33) of the box structure (30) is vertical, the axis (X) of said box structure (30) and of the air flow being oblique.
5. A device according to any one of Claims 1 to 3, in which the axis (X) of the box structure (30) and of the air flow is vertical, the plane containing the opening (33) of the box structure (30) being oblique.
6. A device according to any one of Claims 1 to 5, in which the box structure (30) is a cylinder and the opening (33) is oval.
7. A device according to any one of Claims 1 to 5, in which the box structure (30) is parallelepipedal, the opening (33) being rectangular.
8. A drying chamber (40) in which are arranged parallel rows (C) of stacks
   (A) forming between them corridors (D) through which ventilation devices (E) according to Claims 1 to 7 run.

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