EP0022035A1 - Process and device for depollution in an apparatus for manufacturing a fibrous mat - Google Patents

Abstract

The invention relates to a method and a device for dedusting and depolluting air, in an installation for manufacturing a fiber mat.

The invention provides, under the strip (12) for forming a mattress (13) of fibers, boxes (25) forming Venturi (26) with neck (27) of adjustable section, means (17,18, 19.20, 37) for spraying water on the Venturi (26) and on the walls leading to the suction fans, and lifting means for moving the boxes (25) between an upper service position and a rest position at level of an inspection door (32).

The invention generally applies to installations for forming a glass wool or rock wool mattress.

Description

The invention generally relates to a method and a device for depolluting or cleaning and purifying gases loaded with fibers, dust and gaseous effluents containing polymerizable materials, in an installation for manufacturing a fiber mat, by example of mineral fibers such as glass wool or rock wool, or vegetable fibers such as flax fibers, wood fibers, or any other material.

The mattresses of mineral or vegetable fibers are generally formed by projection of fibers, by means of a rotating die, on a conveyor belt contained in an elongated enclosure. A suction of air under the conveyor belt causes the fibers to settle on this belt, to form a mattress. At the same time as the fibers, a polymerizable binder is also sprayed onto the strip, to agglomerate the fibers into a mat.

In the current technique, the suction of air under the conveyor belt, which is generally of the perforated type, is done by means of suction fans. To prevent particles of polymerizable binder from settling on the walls of the enclosure or conduits located under the conveyor belt and connected to the fans, spray bars for spraying a high-pressure washing liquid, generally water, are provided under the conveyor belt. However, it is found in practice that these measures are not sufficient, and that the polymerizable binder is deposited on the blades of the fan or fans, and solidifies there. This deposit causes a static and dynamic imbalance of the fan blades, which after a very short time can no longer function. It is then necessary to dismantle the fans and clean them with a chisel. The use of a high pressure washing liquid in the spray bars also results in very rapid wear of the spray nozzles, a risk of fouling and clogging of these nozzles, etc. Improper spraying of washing liquid immediately results in a deposit of polymerizable binder and dust on the walls of the ducts leading to the fans.

The object of the present invention is precisely to avoid these drawbacks of the prior art, and for this purpose it proposes a depollution process in an installation for manufacturing a mattress of fibers, such as glass or rock wool, which are projected or deposited with particles or droplets of polymerizable binder on a perforated conveyor belt, characterized in that it consists in providing, under said conveyor belt, a series of means for extracting air loaded with fiber dust and particles or droplets of binder, to regulate the aspiration of these means as a function of their location under the conveyor belt so as to obtain on said band the formation of a mattress of fibers of constant thickness and / or density, to be associated with these suction means means for spraying a washing liquid at low pressure, such as water, so collecting and collecting dust and particles or droplets of binder in suspension in the air and then treating this washing liquid.

According to another characteristic of the invention, this method consists in having, under the conveyor belt, series of Venturi with adjustable section neck, opening into a duct connected to suction means, and spraying sprays of liquid washing at low pressure, such as water, arranged on the one hand at the inlet of the Venturi, and on the other hand downstream of their outlet, to form a runoff of liquid on all the walls of the conduits or means dust collection on which dust and the binder are likely to settle.

The invention also provides a depollution device in an installation for manufacturing a fiber mat, enabling the method according to the invention to be carried out, characterized in that it comprises, under the conveyor belt for forming the fiber mat , an enclosure whose upper part is closed by the conveyor belt and which contains a series of longitudinally aligned boxes, forming Venturi with adjustable section neck, arranged under the conveyor belt, spraying sprays of washing liquid at low pressure such as water, to form a runoff of liquid on the walls of the enclosure and of the caissons, the outlet of said enclosure being connected to air suction means, and adjustment means of the Venturi pass section.

• La figure 1 est une vue schématique en plan représentant l'implantation d'un dispositif de dépollution selon l'invention sous la bande transporteuse de formation d'un matelas de fibres.
• La figure 2 est une vue en coupe à plus grande échelle, selon la ligne II-II de la figure 1.

The invention will be better understood and other objects, characteristics, details and advantages thereof will appear more clearly during the explanatory description which follows, made with reference to the appended schematic drawings given solely by way of example illustrating a mode of the invention and in which:

• Figure 1 is a schematic plan view showing the installation of a pollution control device according to the invention under the conveyor belt for forming a fiber mat.
• Figure 2 is a sectional view on a larger scale, along the line II-II of Figure 1.

An installation for manufacturing a mattress of fibers, such as glass wool or rock wool, generally comprises, very schematically, a forming head 10 such as a rotary die, which projects fibers 11 on a conveyor belt 12 of the perforated type, on which a mattress 13 of fibers is formed. A polymerizable binder is also projected as indicated by the arrows 14, on the conveyor belt 12 with the fibers 11, to form the mattress 13. The enclosure containing the rotary die 10 and the means for spraying binder, has been shown very schematically at 15, and includes air inlets.

The air from the enclosure 15 is sucked through the conveyor belt 12 by suction fans, not shown, mounted at the end of the duct 16. This suction, which takes place over a certain length of conveyor belt 12, makes it possible to attract the fibers and the binder on the belt 12 to form the mattress 13.

It is understood that the air passing through the conveyor belt 12 and sucked through the conduit 16 towards the suction means, is loaded with fiber dust and polymerizable binder, which tend to deposit and stick immediately on all the walls that they may meet between the conveyor belt 12 and the suction means. The mixture of dust and binder stuck on these walls is extremely difficult to remove afterwards.

To solve this problem, the invention therefore proposes a series of means which will be described in detail in the following.

The invention firstly provides booms 17 for spraying a low-pressure washing liquid, such as water, under the conveyor belt 12. The booms 17 extend longitudinally and horizontally under this belt, and they are provided with spray nozzles 18, surmounted by cups 19 and 20, provided at two different heights. The nozzles 18 have a relatively large diameter, so that they cannot become clogged. They are also not subject to very rapid erosion, the liquid circulating in the pipes 17 being at low pressure.

The liquid leaving the nozzles 18 strikes the domes 19 and 20, and is sprayed on the walls of an enclosure 21 situated under the conveyor belt 12. This enclosure 21 is provided with inspection doors 22, allowing the inspection and maintenance of the water spraying systems 17, 18, 19 and 20. A central wall 23 is removably attached to a rod extending just under the conveyor belt 12.

Under the aforementioned enclosure 21, there is another enclosure 24, the upper part of which is connected to the enclosure 21, and the lower part of which is connected to the duct 16 leading to the abovementioned suction fans.

In this enclosure 24 are disposed boxes 25, only one of which is shown in section in FIG. 2, and which are three in number, in FIG. 1, being longitudinally aligned end to end.

Each box 25 comprises two Venturi 26 which are transversely juxtaposed in the box. Each V-shaped Venturi 26 is of elongated longitudinal shape, its neck 27 being constituted by an elongated rectangular slot. The section of the neck 27 is adjustable, by means of a plate 28 which is slidably mounted between two guide plates 29 of the box and the internal end of which more or less closes the slot constituting the neck 27 of the Venturi.

It will be noted that one of the walls 30 forming one of the longitudinal sides of the Venturi ends, under the neck 27, by a curved spoon-shaped part 31.

Each box 25 is mounted vertically movable, in the enclosure 24, between an upper service position which is that shown in FIG. 2, and a lower position, not shown, in which the box 25 is brought opposite a visit door 32 of the enclosure 24. In this lower position, the box 25 can be removed from the enclosure 24, to be cleaned or replaced.

Each box 25 can be supported by a rigid frame connected to handling cables 33 passing over pulleys 34 and arriving at winches 35, or else each box 25 can itself be directly connected to cables 33.

A central wall 36, similar to the above-mentioned removable central wall 23, is hung under each box 36.

• le liquide de lavage à basse pression circulant dans les canalisations 17 est pulvérisé, au moyen des coupoles 19 et 20, sur les parois intérieures de l'enceinte 21 et sur les deux faces opposées de la paroi centrale 23. Ce liquide ruissèle sur ces parois et pénètre dans les caissons 25 (se trouvant dans leur position supérieure de service) en ruisselant sur les parois 30 formant les Venturi 26. Au niveau du col 27, se produit une atomisation assez poussée du fluide s'écoulant à travers les Venturi 26 et comprenant l'eau de ruissellement, et l'air chargé de poussière et de liant. Grâce à cette atomisation, on obtient un mélange intime d'eau de lavage, d'air, de poussière et de liant, les poussières rentrant par choc dans les gouttelettes d'eau.

The device which has just been described operates as follows:

• the low pressure washing liquid circulating in the pipes 17 is sprayed, by means of the domes 19 and 20, on the interior walls of the enclosure 21 and on the two opposite faces of the central wall 23. This liquid trickles onto these walls and penetrates into the boxes 25 (being in their upper service position) by flowing over the walls 30 forming the Venturi 26. At the level of the neck 27, there occurs a fairly extensive atomization of the fluid flowing through the Venturi 26 and including runoff, and air laden with dust and binder. Thanks to this atomization, an intimate mixture of washing water, air, dust and binder is obtained, the dust returning by impact into the water droplets.

The spoon-shaped part 31 placed at the outlet of the neck 27 of each Venturi 26, makes it possible to retransform by shock, the water mist resulting from atomization, in large droplets. The mixture of liquid and air leaving the Venturi 26 is guided, by the parts 31, on the one hand on some of the internal walls of the enclosure 24, and on the other hand on one face of the central wall 36. spraying ramps for washing liquid at low pressure, shown at 37, are provided on the other walls of the enclosure 24, to prevent them from depositing and sticking of dust and binder.

The liquid and the air then flow through the conduit 16.

It can be seen that very good depollution of the air sucked in through the conveyor belt 12 is thus obtained, and that the air which reaches the blades of the fans no longer contains any binder and dust.

The washing liquid laden with dust and binder is treated, in a conventional manner, for the separation of dust and binders, and is then advantageously recycled in the spraying booms 17 and 37.

It will be noted that, advantageously, at least some of the walls of the means which have just been described, and which are capable of receiving a deposit of dust and binder, can be covered with an adhesive plastic sheet which makes it possible to clean very easily these walls. After a certain period of use, it suffices to remove these adhesive sheets and replace them with others.

It will also be noted that the method and the device according to the invention, which have just been described, also make it possible to obtain another extremely advantageous technical advantage.

In fact, like a certain number of boxes 25 (three in number in the example shown in FIG. 1), are longitudinally aligned, under the conveyor belt 12, and substantially from the rotary die 10, it is possible, by adjusting correctly the sections of the necks 27 of the Venturi 26, obtaining over a certain length of conveyor belt 12, a pressure drop profile such that the mattress 13 of fibers formed on the belt 12 has a constant thickness and / or density. In the prior art, which does not allow this adjustment, the fibers tend to deposit on the strip 13 at the place where the suction is strongest, that is to say at the nearest place a suction fan. The method and the device according to the invention make it possible, on the contrary, to obtain a regular and uniform deposit of fibers, over the entire useful length of the forming strip 12.

Of course, the number of boxes 25 which can be provided longitudinally one after the other, is variable to a large extent. Likewise, each box 25 can comprise several Venturi transversely juxtaposed, their number not necessarily being two as in the example shown in FIG. 2.

It is therefore understood that the invention is not in no way limited to the embodiment described and shown which has been given only by way of example, and that it includes all the technical equivalents thereof as well as their combinations, if these are executed and implemented in the The scope of the following claims.

Claims (11)

1. Depollution process in a. installation for manufacturing a mattress of fibers, such as glass wool or rock wool, which are sprayed or deposited with particles or droplets of polymerizable binder on a perforated conveyor belt, consisting of combining suction means of the air laden with fiber dust and particles or droplets of binder, to means for spraying a washing liquid such as water, and then treating this washing liquid, characterized in that it consists of have, under the conveyor belt, series of Venturi with adjustable cross-section, opening into a duct connected to suction means, and spray bars for spraying washing liquid at low pressure, such as water, arranged on the one hand, at the inlet of the Venturi, and on the other hand, downstream of their outlet to form a runoff of liquid on all the walls of the ducts or dust removal means on which dust and the binder are liable to deposit. 2. Method according to claim 1, characterized in that it consists in providing, under the conveyor belt, at least two adjacent rows of longitudinally aligned Venturi. 3. Method according to one of the preceding claims, characterized in that it consists in protecting at least some of the walls of the aforementioned conduits and suction means by sheets of flexible plastic material, removably attached for example by means of 'an adhesive on these walls. 4. depollution device in an installation for manufacturing a fiber mat, allowing the execution of the method described in one of the preceding claims, characterized in that it comprises, under the conveyor belt for forming the fiber mat , an enclosure, the upper part of which is closed by the conveyor belt and which contains a series of longitudinally aligned boxes, forming Venturi with adjustable cross-section, arranged under the conveyor belt, spray bars for spraying washing liquid at low pressure, such as water, to form a runoff of liquid on the walls of the enclosure and of the boxes, the outlet of the enclosure being connected to air suction means, and adjustment means of the Venturi pass section. 5. Device according to claim 4, characterized in that the Venturi are of elongated longitudinal shape, with a substantially V-shaped cross section, the neck of each Venturi being constituted by a slot of substantially rectangular elongated shape with adjustable width. 6. Device according to claim 4 or 5, characterized in that the outlet of each Venturi comprises a longitudinal plate with curved section, on which is projected the flow of fluid leaving the Venturi. 7. Device according to one of claims 4 to 6, characterized in that the aforementioned boxes are mounted vertically movable inside the enclosure, between an upper service position where they are pressed tightly on a horizontal wall top of the enclosure, and a position lower rest, located at the inspection doors provided in the wall of the enclosure allowing said boxes to be removed from the enclosure. 8. Device according to claim 7, characterized in that the boxes are supported by rigid frames, connected to lifting means, for example of the cable type, making it possible to move the boxes between their two aforementioned positions. 9. Device according to one of claims 4 to 8, characterized by ramps for spraying lifting liquid, extending longitudinally above the inlet of the Venturi, and provided with spray nozzles at two different levels. 10. Device according to one of claims 4 to 9, characterized in that at least one of the walls of the enclosure comprises, downstream of the Venturi, a spray boom for spraying a washing liquid. 11. Device according to one of claims 4 to 10, characterized in that it comprises several boxes longitudinally juxtaposed, each box comprising at least two Venturi transversely juxtaposed.

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