FR2973100A1 - AIR FLOW DIFFUSION INSTALLATION - Google Patents

Abstract

The invention relates to an airflow diffusion installation for diffusing air into a localized volume, said installation comprising a working surface (40), airflow diffusion means (2), transparent guide walls (3). According to the invention, said installation comprises suction means (5) and said guide walls comprise at least two outer guide walls (31), and two inner guide walls (30) which extend between the walls of external guidance (31). Said guide walls and said diffusion means (2) are arranged in such a way that the diffused air flow (8) is distributed in a central air flow, diffused between the inner guide walls, a flow of air lateral, diffused between each inner guide wall and the corresponding outer guide wall, and a flow (82) of air outside each outer guide wall (31).

Description

The present invention generally relates to airflow diffusion installations.

The invention relates more particularly to an air flow diffusion installation. Said installation comprises a working surface having two opposite edges, diffusion means for diffusing a flow of air towards the working surface, and a set of transparent guide walls located in the extension of the diffusion means.

In the food industry, controlling the cleanliness and temperature of the air in contact with food is one of the key points of hygiene in the workshops. In this area, diffusion installations are used to dispense clean and cold air, that is to say generally between 0 ° and 4 °, lower than the ambient air temperature around the room. installation, on 15 products to protect them in sensitive areas of work against pollution, particulate or otherwise, transported by air.

Indeed, the manufacture and packaging of a large number of perishable goods, such as cooked products, require cold environments 20 and ultra-clean. However, working in workshops maintained at temperatures of the order of 0 ° C harms the comfort and health of operators. However, the diffusion installations known in the state of the art generate in the work area products a cold air flow which tends to mix with the ambient air, outside the work area, in which 25 places an operator, which is detrimental to his working conditions.

Thus, prolonged cold mobilizes additional muscle efforts, likely to accentuate musculoskeletal disorders causing chronic and disabling pain. A cold thermal environment is a direct risk factor for the operator, especially for carpal tunnel syndrome. In addition, a cold environment requires the operator to use a surplus of clothing protection, which hinders his movements and therefore in his work. Finally, a cold atmosphere causes the operator a loss of dexterity and grip strength.

In general, the aim of the present invention is to propose an air diffusion installation making it possible to diffuse on air handling products a flow of air of different temperature compared to that of the ambient air, while limiting the physical and thermal exchanges between the diffused air and the ambient air of the zone in which the operator or operators are located to improve their working conditions. In particular, the present invention aims to provide an installation for continuously diffusing and in a localized space, air at a given temperature to maintain the products at this temperature, and clean to protect said or said products of air contamination, while limiting the negative effects of the difference in temperature between the air diffused in the working volume of the products and the ambient air around the installation on the working conditions the operator or operators.

The present invention also aims to limit the energy consumption of the installation.

To this end, the subject of the invention is an air flow diffusion installation for diffusing air into a localized volume, also called a useful volume, within which at least one product is capable of be present, said installation comprising: - a working surface, able to support said at least one product, said working surface having two opposite edges, called longitudinal edges, 30 - diffusion means for diffusing an air flow in direction of said working surface, - a set of transparent guide walls located in the extension of the diffusion means, characterized in that said installation comprises suction means having at least one suction opening along at least one a part of each longitudinal edge of the working surface, and in that said set of guide walls comprises at least two so-called outer guide walls, and two guide walls said inner guide walls, which extend between the two outer guide walls, said outer and inner guide walls being spaced from each other and, preferably, parallel to one another, said guide walls and said diffusion means being arranged of such that the air flow diffused by said diffusion means is distributed in a flow of air, said central air flow, diffused between the inner guide walls, an air flow, said lateral air flow , diffused between each inner guide wall and the facing outer guide wall, and an air flow, said flow of outside air, diffused on the outer side of each outer guide wall.

The arrangement of said suction openings along two opposite edges of the working surface makes it possible to channel the diffused air and thus to at least partially delimit said localized space, also called useful working volume, or work area, to through which the air is diffused, so that it does not flow towards the operators. Said diffused air is advantageously a so-called cold air, that is to say a temperature below the ambient temperature around the installation, preferably at least 13 ° C., and generally between -2 ° C. and 4 ° C. More generally, the diffused air has, relative to the ambient air of the zone in which the installation is located, or the operator or operators, a temperature difference, preferably of at least 10 °. vs.

In the case of cold air diffusion, such a design of the installation makes it possible to maintain said products present on the work surface in a clean and cold environment, while allowing each operator to be kept in a different environment. higher temperature, preferably of the order of 16 ° C, substantially homogeneous, which meets the so-called PMV criterion for Predicted Mean Vote in English, in accordance with ISO7730.

In fact, the ambient air of the work premises must meet certain requirements in order to guarantee the thermal comfort of the employees. There is sensation of thermal comfort for an individual when energy exchanges between the body and the environment are performed without strain. The ISO 7730 standard presents, for moderate thermal environments, a method for predicting thermal sensation and specifies acceptable conditions of comfort. It defines said "PMV" index which gives the average opinion of a group of people expressing a thermal sensation vote according to parameters such as measurable thermal environment parameters, for example temperature, air speed. , radiation, hygrometry, and, optionally, estimated parameters, for example clothing and activity.

The suction means make it possible to reduce the risk of mixing between the diffused air and the ambient air of the zone in which the operator is located. Said suction means reinforce the air flows diffused through the set of walls, in particular the lateral and external air flows, and generate a preferred direction for said diffused air streams on the products, which limits the losses of the air diffused towards the ambient air of the zone in which the operator (s) is located. Said suction means distributed on either side of the working surface thus make it possible to preserve the ambient conditions around each operator and the temperature conditions of the air diffused on each product present in the working zone.

The installation according to the invention makes it possible to improve the quality and the guiding of the circulation of air diffused through said localized space traversed by the products and open on the zone in which the operator or operators is located, limiting the risk of disturbance of the diffused air flow. Said area in which is located said or each operator is adjacent to said useful volume through which the products and through which the air is diffused.

Such a design of the installation makes it possible to keep on both sides of the inner and outer guide walls of the globally laminar air flow whose trajectory is made reliable by the combination of the guide walls and the suction means of the air, so that the diffused air flows do not diffuse into the ambient environment in which the operators are located.

Thus, in the field of food industry workshops, the installation according to the invention makes it possible to deliver cold airflows on the worktop, while establishing airspace boundaries between the atmosphere of the workshops and the atmosphere. atmosphere that must be maintained in the immediate vicinity of products for health reasons or for the preservation of quality.

As a result, the installation according to the invention makes it possible to reconcile health performance and improvement of working conditions in the food industry. Said installation also makes it possible to separate, at lower cost, the temperate atmosphere of a workshop, from a temperature of between 13 ° C and 18 ° C, of the ultra-clean and cold environment with a temperature of between -2 ° C. C and 4 ° C, around the product or products to handle.

Finally, each external air flow, that is to say each flow which extends on the outside of the corresponding outer guide wall, in combination with the openings, allows the suction means situated substantially in the extension. said flows, to form a stable air barrier between the diffused central and lateral air flows which impact the products and the ambient air of the outer zone in which the or each operator is located, which makes it possible to obtain in said ambient zone of the or each operator an air velocity of less than 0.2 m / s in order to limit the sensation of temperature variation, especially of cold, in the zone of evolution of the operators.

In particular, each external air flow which licks the outer face of each outer guide wall forms a fluid barrier between the corresponding lateral air flow and the ambient air of the zone in which the operator is located, which makes it possible to act in stabilization on a possible turbulent flow which could be formed at the level of said lateral flow, in particular when the arm of the operator (or any other tool or obstacle) crosses said lateral flow. In addition, the diffused air which licks the outer face of each outer guide wall makes it possible to avoid the appearance of condensation on said outer guide walls, which guarantees good visibility for the operators through said guide walls. and thus improves the working conditions of the operators, in particular when two operators are working in vis-à-vis. Advantageously, an operator is located on the side of each opposite edge of the working surface at which extends a suction opening.

According to an advantageous characteristic of the invention, said installation comprises conveying means having a conveying surface forming said working surface, said conveying means comprising means for moving said conveying surface and said conveying surface having two edges. opposing longitudinal members which extend substantially in the direction of travel, and which form said opposite edges of the work surface. Thus, said suction openings are distributed on either side of the longitudinal axis of the conveying surface corresponding to the axis of travel of said conveying means. According to an advantageous characteristic of the invention, the guide walls are located in a plane orthogonal to the working surface and parallel to the median axis of the working surface, said longitudinal axis, which extends between said opposite edges of said working surface, said median axis corresponding to the axis of travel of said working surface when the latter is a conveying surface.

Such a design and such an arrangement of the guiding walls makes it possible to obtain diffused air curtains which extend in a longitudinal vertical plane above the products and which form, with respect to each other, aeraulic barriers making it possible to stabilize the or the adjacent air flows, so as, in cooperation with the suction means, to contain said air diffused into said useful volume of passage of the products, limiting the mixing of the diffused air with the ambient air in which is present the or each operator, that is to say while keeping around the operator a temperate temperature not influenced by said diffused air.

According to an advantageous characteristic of the invention, said outer walls extend between and away from said opposite edges of said working surface.

According to an advantageous characteristic of the invention, the set of guide walls is arranged with the working surface so as to provide a free space between said working surface and said set of guide walls.

According to an advantageous characteristic of the invention, said installation also comprises at each end of the set of guide walls, a so-called front end wall, respectively a rear end wall, which extends orthogonally to the guide walls. and at the work surface, so as to at least partially close the front and rear ends of the guide wall assembly. According to an advantageous characteristic of the invention, at least one of said front and rear end walls, has at least one lower part spaced from the working surface by a distance of between 10 and 20 cm to generate a curtain of dynamic dedusting of the products by the clean air diffused by said diffusion means which escapes naturally from said localized space in which said air is diffused.

According to an advantageous characteristic of the invention, said suction means comprise at each of said opposite edges of the working surface, a box provided with said at least one air suction opening and two columns arranged at , or in the vicinity of the ends of said box capable of recovering the aspirated air flows and redirecting them towards said diffusion means, which are preferably associated with cooling means.

According to an advantageous characteristic of the invention, said installation comprises means for filtering the air flow diffused by said diffusion means, positioned upstream of said set of guide walls.

According to an advantageous characteristic of the invention, said filter means adjoins the set of guide walls by interconnecting the edges of the inner and outer guide walls opposite the free edges of said guide walls situated on the side of the surface of the guide. job.

Such an arrangement of the filtering means applied against the set of guide walls makes it possible to filter the airflow diffused, very downstream, so as to limit the risk of contamination of said air, while minimizing pressure losses. undergone by said airflow.

According to an advantageous characteristic of the invention, said suction openings are located flush with the working surface or below said working surface.

Such an arrangement of the suction openings makes it possible to suck up the air flows coming from the set of guide walls, after their impact on the working surface by accompanying them as close as possible to the working surface to reduce turbulence. and thus limit the risk of said air flows flowing out of said localized working space of the products to the environment of the operator or operators.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings, in which: FIG. 1 is a perspective view of the installation according to the invention; - Figure 2 is a partial perspective view of all the guide walls of the installation of Figure 1; FIG. 3 is a cross-sectional view of the installation of FIG. 1; FIG. 4 is a detailed view of the flows of cold air flow from the diffusion means to the suction means of the installation of FIG. 3, on one side of said installation.

Said products are preferably agri-food products but may be formed by other products, in particular sensitive products requiring to be cooled or kept at temperature by a cold and clean air, that is to say practically free of particles contaminants, such as pharmaceuticals. Advantageously, said clean air has an ISO06 level cleanliness (ISO 14644-1 standard) corresponding to a cleanliness class 1000. Cold air is understood to mean an air of temperature lower than the ambient air temperature, preferably of at least 10 ° C, and generally between -2 ° C and 4 ° C.

With reference to the figures and as recalled above, the invention relates to a cold air flow diffusion installation capable of maintaining or cooling products at a given temperature. Said installation makes it possible to diffuse cold air into a localized space 43, that is to say a space of limited size, within which at least one product to be handled by one or more operators. In the example illustrated in the figures, said localized space 43 is a space through which said products are intended to be conveyed to be worked by one or more operators. Said localized space 43 is also called useful working volume. Said installation comprises a working surface 40 on which the products to be handled can rest.

In the example illustrated in the figures, this working surface is movable and formed by the conveying surface of conveying means 4 provided with means for moving said conveying surface. Said conveying surface may be a conveying or thermoforming-film strip, ensuring the scrolling of products through said localized space. Alternatively, said work surface may be a fixed work surface. Said working surface 40 has two opposite edges, called longitudinal edges, which extend substantially along said direction of travel.

As detailed hereinafter, the localized air diffusion space 43 is delimited by the set of guide walls and the working surface facing said set of guide walls. Said localized air diffusion space 43 has two opposite sides delimited between one edge of said working surface and the outer wall of the guide assembly closest to said edge, and the other between the opposite edge. of said working surface and the corresponding outer wall of the guide assembly. Thus, said localized space is open on two opposite sides corresponding to the opposite longitudinal edges of the working surface along which the operators are positioned. Thus, the manipulations by the operators of the products located in the localized space 43 are possible from two opposite longitudinal edges of said localized space.

Said installation also comprises means 2 for diffusing cold air, and a set 3 of transparent guiding walls located in the extension of the diffusion means 2.

For the production of the cold air flow, it can be provided that said installation comprises means for producing cold air or that these are outsourced. Preferably, said diffusion means 2 comprise means for forced circulation of air, such as a fan. Said diffusion means 2 also comprise a diffusion box 21 configured to allow diffusion of the cold air flow between the guiding walls which extend it and the outer side of said outer guide walls.

Said diffusion box 21 forms a ceiling above the useful working volume and the work surface forms a floor.

Said plant comprises suction means 5 having at least one suction opening 50 along at least a portion of each longitudinal edge of the working surface 40.

Said guide walls 30, 31 comprise at least two so-called outer guide walls 31 and two so-called inner guide walls 30 which extend between the two outer guide walls 31, the inner guide walls 30, 31 and outermost being preferably parallel to each other.

Said inner and outer guide walls 30, 31 and said diffusion means 2 are arranged in such a way that the air flow 8 diffused by said diffusion means 2 is distributed in an air flow 80, called flow of air. central air, diffused There enters between the inner guide walls, a flow 81 of air, said lateral air flow, diffused between each inner guide wall 30 and the outer guide wall 31 located opposite, and a flow 82 of air, said flow of outside air, diffused on the outside of each outer guide wall 31.

Said useful volume through which cold and clean air circulates corresponds to a working area of the products of width corresponding to the width of the working surface, of length corresponding to the length of the guide walls, that is to say say to the spacing between the front and rear end walls, and height corresponding to the distance between the lower edge of the guide plates and the working surface. This useful volume corresponds to the volume swept by the cold and clean air which is also open to the environment of the operator to enable him to manipulate the products present in said useful volume.

The combination of external flows 82 and side 81 obtained through the walls of inner and outer guides, and the suction means 5, can contain the cold air in said useful volume so that it does not flow into the environment of the operator (s).

In particular, the outer guide walls lined with the inner guide walls make it possible to obtain a central flow between the inner guide walls and a lateral flow on each side of the central flow, as well as an external flow which licks the outer face of the inner flow. each outer guide wall.

Said streams then have substantially the same direction, mostly vertical, then are distributed to the opposite longitudinal edges of the working surface at which they are sucked by the corresponding suction openings.

The guide walls and the filtering means which adjoin the guide walls upstream of said guide walls, also allow to keep cold and clean air in the work area of the products.

The guide wall assembly defines a cold and clean air containment space open above the work surface.

This results in a stabilization of the central air flow and lateral flows thermally and physically, thanks to the thermal and physical barrier formed by the lateral flows on the central flow and thanks to the thermal and physical barrier formed by the external flows on the lateral flows. In particular, each external flow in contact with the ambient air of the zone in which an operator is located has a warm temperature which reduces the temperature gradient between the air of the lateral flows and the ambient air of the zone in which locates the operator, which limits the thermal and physical instability of the ambient air at the boundary between the localized working space and the area where the operator is located.

Such an efficient guidance of the cold air, the limitation of the cold air leaks out of the useful working volume of the products, and the stability of the cold air flows in this volume, are obtained thanks to the combination of the guide walls. internal and external, diffusion means and suction means.

The doubling of the outer side walls by the inner side walls allows the cold air to be blown to the working volume delimited between the free lower ends of the side walls and the working surface, preventing any destabilization of the cold air flow. upstream of this useful volume of work.

When the vertical cold air flows 80, 81, 82 descendants meet the working plane formed by the working surface 40, their impact on this plane creates an outwardly oriented horizontal flow deflection of the working volume 43 which prevents any aerodynamic disturbance from entering this useful volume.

The lateral suction openings provided at the edges of the working plane formed by the working surface 40 make it possible to stabilize these horizontal flows while isolating them from the flows of outside air currents which are also attracted by these suction openings.

The ambient air close to the diffused external flow 82 is automatically dragged under the effect of the viscosity (induction phenomenon) in a descending vertical movement converging towards the suction openings 50, which makes it possible to reduce the horizontal gradient of temperature between the cold flows of the useful volume and the warm ambient air of the zone in which the or each operator is located. This reduction of the gradient contributes greatly to the dynamic and thermal stability of the air boundary which separates the useful working volume from the zone in which the or each operator is located.

The inner and outer guide walls 30, 31 are located in a plane orthogonal to the working surface 40, and parallel to the running direction of said working surface 40 when it is of the conveying surface type, it is in a vertical longitudinal plane.

Said outer walls 31 also extend in a space delimited between and set back from the longitudinal edges of said working surface 40. By the terms "indented" is thus meant the fact that the outer walls 31 extend straight out. of the diffusion box 21 and spaced longitudinal edges of said diffusion box 21.

The recessed disposition of said outer guide walls allows operators located on either side of the working volume of products, to work in a comfortable position since they can advance the head above the edges of said work surface without be hampered by said outer guide walls. The assembly 3 of guide walls is arranged with said working surface 40 so as to provide a free space between said working surface and said set 3 of guide walls, to allow operators located on either side of the 3 set of guide walls to access and handle the products that are in said working area formed by the useful volume 43.

Said installation also comprises at each end of the set of guide walls 3, a wall 32 referred to as a front end wall, respectively a rear end wall, which extends orthogonally to the inner and outer guide walls 30, 31 and 31. to said work surface 40, so as to close at least partially at the top the front and rear ends of the guide wall assembly 3 to contain the flow of air blown through said guide wall assembly.

Said front and rear walls 32 extend, in a direction orthogonal to the working surface 40, a greater distance than the guide walls 30, 31, so that the distance between each guide wall 30, 31 of the working surface 40 is smaller than that which separates the walls of the assembly 3 of guide walls from said working surface 40.

At least one of said front and rear walls 32 is of sufficient length to generate a dynamic dust removal curtain as the products run past the work surface 40 and pass under said end wall. Said front and rear walls 32 are preferably spaced apart from the working surface 40, a distance for example of the order of 20 cm to let the products. These front and rear walls 32 are offset with respect to the corresponding end edge of the diffusion box 21 in the longitudinal direction of the box by a distance of between 2 cm and 5 cm, for example 3 cm.

Preferably, the end walls 32 and the outer guide walls 31 are joined to best contain the flow of air diffused to the work area.

In the example illustrated in the figures, the guide walls are located in a longitudinal vertical plane and stop at a distance from the work plane of the order of 50 cm to allow manual access for operators to products that pass to through said useful working volume 43.

The outer guide walls are set back from the corresponding longitudinal edge of the diffusion box 21 by a distance of between 1 cm and 5 cm, so that each outside air flow has a small width of between 1 and 5 cm, less than the width of the lateral air flows and the width of the central air flow, which stabilizes the lateral air flows diffused between inner walls and outer walls without disturbing the ambient air of the zone in which locate the or each operator.

In the example illustrated in the figures, said suction means 5 comprise on each side of the working surface 40, with respect to the longitudinal axis corresponding to the direction of travel, a box provided on the top with said opening air suction 50 and two columns 6, disposed at or near the ends of said box capable of recovering the flows 80, 81, 82 of air sucked and redirecting them through a collection box 7 located above the diffusion box 21, to the cold air production means (not shown) to be reinjected into said diffusion means 2.

Said installation comprises means 20 for filtering the air flow diffused by said diffusion means 2, positioned upstream of said set 3 of guide walls, with reference to the direction of the flow of the diffused air.

The air diffused through the useful working volume 43 is sucked by the air suction means 5 and recirculated by the columns 6 to a collection box 7 to be recycled through the air production means The filtering means 20 are preferably formed at the bottom face of said diffusion box 21. The bottom face of the box corresponds to that from which extend the walls of the assembly 3 of guide walls.

Said bottom face allows the passage of cold air from inside the box to the outside of the diffusion box 21 towards the assembly 3 of guide walls. It can thus be provided that the bottom face of the diffusion box is formed by said filtering means 20. Said filtering means 20 extend over a distance, taken in a direction parallel to the direction of separation of the guide walls. , greater than said spacing distance of the outer guide walls 31, so as to allow to blow a filtered air on either side of the outer guide walls. Said filtration means 20 extend in a substantially horizontal plane, that is to say substantially parallel to the plane of the working surface 40.

Said filtration means 20 formed in the diffusion box 21 make it possible to filter and distribute the flow of air over the entire bottom face of the box in a predetermined direction, substantially orthogonal to the working surface 40, by example a substantially vertical direction, and with a speed distribution close to the uniform. Said filtration means may comprise one or more filters called HEPA filters (High Efficiency Particulate Air-filter in English) in accordance with the EN 1882 standard.

Said filtering means 20 adjoin the assembly 3 of guide walls by interconnecting the edges of the inner and outer guide walls opposite the free edges of said guide walls situated on the side of the working surface 40. In other words, assembly of guide walls 3 extends the filtering means, with reference to the direction of circulation of the air diffused. Such a design of the installation makes it possible to filter the air as close as possible to the assembly 3 of guide walls and thus to homogenize the distribution of the air flow diffused by said diffusion means 2 over the whole of the zone of distribution of the guide walls 30, 31 and thus to limit the risk of contamination of the diffused air.

Said filtration means 20 are situated on the opposite side to the working surface 40 with respect to the assembly 3 of guide walls. According to a variant, the bottom face of the diffusion box 21 is formed by a diffusing screen ensuring, as does a HEPA filter, a homogeneous distribution of the air diffusion rates, without ensuring high efficiency filtration. In this case, the filtration of the air is ensured in a filtration device situated upstream of the diffusion box 21, or the device diffuses cold air without ensuring ultra-cleanliness in the localized volume 43.

The suction openings 50 are flush with the upper face of the work surface 40 or at a recessed height from said work surface 40.

Cold air diffusion installations can also be used in other types of industry than the food industry, for example the pharmaceutical industry, medical and hospital premises or the electronics industry.

The installation according to the invention makes it possible to control the boundary zones between diffused air and ambient air in order to limit the risks of contamination during the handling of the products and to maintain a temperature between -2 ° C. and 4 ° C. close to the product. , while keeping a tempered room between 13 and 18 ° C, respecting at the level of the operator a temperature gradient from the head to the foot lower than 3 ° C.

Such an installation makes it possible to limit the cooling capacity by 50% compared to a conventional equipment of a refrigerated room. The installation according to the invention therefore requires less installed power and less refrigerant mobilized for a production of cold air and clean more homogeneous in space and time.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant lo consistent with his spirit.

Claims (11)

REVENDICATIONS1. An airflow diffusion apparatus for diffusing air into a localized volume (43), also called useful volume, within which at least one product is likely to be present, said installation comprising: a working surface (40), adapted to support said at least one product, said working surface having two opposite edges, called longitudinal edges, - diffusion means (2) for diffusing a flow of air (8) in the direction of the working surface (40), - an assembly (3) of transparent guide walls located in the extension of the diffusion means (2), characterized in that said installation comprises suction means (5) 15 having at least one suction opening (50) along at least a portion of each longitudinal edge of the working surface (40), and in that said guide wall assembly (30, 31) comprises at least two so-called outer guide walls (31) and two guide (30) said inner, which extend between the two outer guide walls (31), said inner and outer guide walls (30, 31) being spaced from each other and, preferably, parallel between they, said guide walls (30, 31) and said diffusion means (2) being arranged in such a way that the air flow (8) diffused by said diffusion means (2) is distributed in a stream of air (80), said central air flow, diffused between the inner guide walls (30), a flow (81) of air, said lateral air flow, diffused between each inner guide wall (30) and the outer guide wall (31) facing, and a flow (82) of air, said external air flow, diffused on the outer side of each outer guide wall (31). 30 2. Installation according to claim 1, characterized in that said installation comprises conveying means (4) having a conveying surface forming said working surface (40), said conveying means (4) comprising means for scrolling said conveying surface and said conveying surface having two longitudinal edges which extend substantially in the direction of travel, and which form said opposite edges of the working surface (40). 3. Installation according to one of the preceding claims, characterized in that the guide walls (30, 31) are situated in a plane orthogonal to the working surface (40) and parallel to the median axis of the work surface. extending between said opposite edges of said work surface (40). 4. Installation according to one of the preceding claims, characterized in that said outer guide walls (31) extend between and recessed from said opposite edges of said working surface (40). 15 5. Installation according to one of the preceding claims, characterized in that the assembly (3) of guide walls is arranged with said working surface (40) so as to provide a free space between said work surface (40) and said set (3) of guide walls. 20 6. Installation according to one of the preceding claims, characterized in that said installation also comprises at each end of the set of guide walls (3), a wall (32) said front end wall, respectively wall of rear end, which extends orthogonally to the inner and outer guide walls (30, 31) and the working surface (40), so as to at least partially close the front and rear ends of the assembly (3) of guide walls. 7. Installation according to claim 6, characterized in that at least one of said walls (32) front and rear end, has at least a portion 30 and spaced apart from the working surface (40) of a distance between 10 and 20 cm. 8. Installation according to one of the preceding claims, characterized in that said suction means (5) comprise, on each side of the working surface (40), a box provided with said at least one suction opening d air (50) and two columns (6) disposed at or near the ends of said box capable of recovering the flows (80, 81, 82) of air by suction and redirecting them to said diffusion means ( 2) which are preferably associated with cooling means. 9. Installation according to one of the preceding claims, characterized in that io said installation comprises filtering means (20) of the flow (8) of air diffused by said diffusion means (2), positioned upstream of said assembly ( 3) guide walls. 10. Installation according to claim 9, characterized in that said filter means (20) adjoin the assembly (3) of guide walls by interconnecting the edges of the inner and outer guide walls opposite the free edges of said walls. on the side of the working surface (40). 20 11. Installation according to one of the preceding claims, characterized in that said suction openings (50) are located flush with the working surface (40) or below said working surface (40).