EP0046137A1 - Cleansing hood for gaseous fluids - Google Patents

Abstract

1. Cleansing hood for gaseous fluids, comprising an exterior housing (1), a motor (5) driving a rotor (13) adapted to generate simultaneously a ventilation function and a purifying function of polluting solid and liquid particles suspended in the fluid to be purified, characterized by the fact that the polluting particles are removed by adsorption on corrugated surfaces which make up said rotor, such as to produce a turbulent flow around these surfaces and to constrain said flow to sweep over the said surfaces without passing through them, the rotor being followed by a filter (21) designed to neutralize or transform the undesirable gaseous components contained in said fluid flow following the purification effected by the rotor.

Description

The subject of the invention is a gaseous fluid purifier consisting of a hood comprising an external frame, a motor driving a rotor acting simultaneously as a fan and purifier of the gaseous fluid which it sucks in the hood, followed by a filter through which said flow of the gaseous fluid passes, capable of neutralizing or transforming the particles of undesirable gaseous components, still contained in the fluid.

Purification hoods for gaseous fluids are generally constructed on the principle of filtration by the forced passage of the fluid, under the action of a fan, through one or more filters placed in series in the hood. There are also electrostatic separators, in which the gaseous fluid, sucked in by a fan, travels through a battery of electrodes charged with static electricity on which the impurities are deposited. In the pasture In the first case, the filters which retain the impurities are more or less quickly saturated, and they must then be cleaned or changed to fulfill their function again. Likewise, in the second case, the electrodes must be cleaned frequently, otherwise the electrical circuit will fail or harmful gas produced.

The object of the invention is to remedy these drawbacks and to present a hood in which the purification of the gaseous fluid is carried out in two stages: firstly the retention of solid and liquid particles, of all sizes, on the rotor surfaces without crossing them, and then neutralization of undesirable gaseous components by the filter placed at the outlet of the hood.

There is therefore firstly a physical purification of all the solid and liquid particles suspended in the fluid to be purified, followed by neutralization, a conditioning of the fluid, or a chemical purification of the harmful gases, in a filter conditioned for this purpose.

The hood according to the invention is characterized in that the rotor is placed at the inlet of the hood to simultaneously generate a ventilation function and a purification function by an arrangement of alternate left surfaces and / or parts of flat surfaces forming angles between them so as to produce a turbulent flow of the gaseous fluid which they displace and to force said fluid to lick said surfaces without passing through them. According to a preferred embodiment, the rotor has a sun pleated shape, it is executed in a fibrous material with rough surfaces. The degree of fouling of the rotor surfaces is visible at all times since they are not crossed by the impurities they retain. At saturation of impurities, the rotor is replaced by standard exchange and destroyed, it can also be executed in a solid and washable material, but this operation is certainly more expensive than the price of a new rotor.

The pressure drops at the suction of the gaseous fluid in the hood according to the invention are very low, since the flow of the fluid to be purified enters freely in the hood as soon as the rotor is set in motion. This results in the possibility of using low power motors rotating at low speeds to drive the rotor. At equal flow, the hood will be less noisy and more economical in energy consumption if a comparison is made with traditional hoods which purify by means of filters through which the flow of the gaseous fluid passes.

To prevent the discharge of the fluid pressurized into the hood by the movement of the rotor, an aerodynamic seal is placed in the inlet opening of the gaseous fluid in the hood, so as to extend - over part of the periphery of the rotor without touching it. This aerodynamic joint is produced in the form of a folded strip forming a serpentine surrounding the hood opening, or of a smooth frustoconical surface whose surface of the suction hole is smaller than the surface of the rotor. This aerodynamic seal is intended to oppose the discharge of gaseous fluid through the suction port of the hood.

The filter placed at the outlet of the hood the invention is crossed by a flow of the gaseous fluid physically purified from the solid and liquid particles which it conveyed at the inlet of the hood. This filter is therefore protected against the influence of these pollutants. This filter can be impregnated with a reagent intended to neutralize or transform the particles of undesirable gaseous components still contained in the fluid to be purified. This reagent can consist of a chemical impregnation of the filter, of water or of steam to humidify the purified gaseous fluid, of perfume or on the contrary of deodorant, etc. To neutralize food cooking odors, this filter consists of a bed of granulated charcoal, the effectiveness of which is not impaired, even after three years of use, thanks to the good protection provided by the rotor. , which perfectly retains water vapor and grease.

The hood according to the invention is light and compact. It is independent of any pipe and requires only a low-voltage single-phase socket for its power supply. By allowing the purified and deodorized fluid to be recycled in the ambient air, this hood does not cause any heat loss in the room in which it is installed. The filter placed at the top of the hood practically does not clog, since the particles which foul the filters of the hoods of the prior art are retained on the surfaces of the rotor-adsorbent. This has the consequence that the hood has an efficiency much higher than that of conventional hoods in operation.

The drawing shows, by way of example, a mode of operation of a gas purifying hood according to the invention.

• La fig. 1 représente une vue en perspective de dessous d'un mode d'exécution de la hotte d'épuration,
• la fig. 2 une coupe à travers la hotte selon la ligne II-II de la fig. 1, et
• la fig. 3 une coupe à travers une variante du bas de la hotte de la fig. 2.

In the drawing:

• Fig. 1 represents a perspective view from below of an embodiment of the purification hood,
• fig. 2 a section through the hood according to line II-II of FIG. 1, and
• fig. 3 a section through a variant of the bottom of the hood of FIG. 2.

The exhaust gas cleaning hood shown in fig. 1 and 2 of the accompanying drawing comprises a circular frame 1 in the form of a cylinder and having inside it two annular rings 2 and 3 (Fig. 2) which will serve as a support for retaining the internal parts of the hood described more far. Between the crowns 2 and 3 is fixed a circular base plate 4 intended to form the horizontal frame of the hood and on which is fixed a motor 5 by means of fixing lugs 6. A protective cylinder 7 is placed around the motor 5 and fixed on the plate 4. The plate 4 has openings 8 regularly distributed around its periphery and placed adjacent to the interior surface of the circular frame 1. The crowns 2, 3 and the plate 4 are fixed to the frame 1 by welding, same as the protective cylinder 7 which is itself welded to the plate 4. It goes without saying that the parts 2, 3, 4 and 7 can be joined by any other known means, for example riveting, bonding, etc. or be formed in one piece with the coat circular 1 in the case where the hood is produced by molding. The hood casing made up of parts 1, 2, 3, 4 and 7 can be made of sheet metal, light metal or plastic. It is obvious to a person skilled in the art that the frame 1 can also be presented for example in square form, so that it can be embedded in an arrangement of prefabricated modules, as is the case for example for the arrangement of kitchens. or laboratories.

The motor 5 comprises a shaft 9 whose axis coincides with the vertical axis of symmetry 10 of the hood shown in the drawing. The shaft 9 of the motor 5 crosses at 11 the plate 4 and has at its free end a locking sleeve 12 on which is fixed a pleated rotor 13 by means of a circular plate 14, itself fixed on a neck 15 integral with the sleeve 12.

The pleated rotor 13 is in the form of a pleated disc having at its center a central opening whose diameter is larger than that of the sleeve 12 on which the pleated disc is centered. The central opening of the pleated disc is maintained at a constant diameter by a wire represented at 16 adjacent to the opening and passing through all the folds of the rotor 1 and the pleated disc is maintained on the plate 14 at its periphery by any known means such as such as bonding, riveting, etc. The pleated disc can be made of any thin material having rough surfaces. According to one embodiment, it is produced from a cellulose paper with a rough surface, such as blotting paper. According to other variants, it can be made from all kinds of fibers (cotton, wool, polyester, glass) agglomerated or woven so as to be in the form of a sheet with a rough appearance. It can also be produced from an agglomerate of fibers or metallic threads or from a thin sheet on the surfaces of which a thin layer of wool or metallic threads are agglomerated. According to another variant, the pleated rotor or disc 13 can also be produced from a cellular plastic material.

Those skilled in the art will readily understand that the material used to make the rotor 13 must have only one important characteristic: it must have a rough surface with visible asperities on which the liquid and solid particles in suspension in the gaseous fluid to be purified by means of the hood can hang and fix.

The plate 14 can also be made of the same material as the pleated disc 13 and constitute a removable assembly with the said disc. In the case where the plate 14 will only be a support piece, it will have hooking means, not shown, to allow the pleated disc or the VELCRO supports to be fixed.

A removable base 17 in the form of an annular crown with a central circular opening 18 is applied against the crown 3 of the frame 1 and fixed in a removable manner against the latter by means not shown. The removable bottom 17 has on its upper surface a cylindrical part 19 concentric with the opening 18 and intended to retain a fixed aerodynamic seal 20 produced from a ban pleated whose two ends are joined to form an annular coil. The seal can be made of the same material as the rotor 13. As shown in the drawing, it covers part of the periphery of the rotor 13, without touching said rotor. Like the rotor, it is interchangeable after removing the removable base 17.

According to the variant of FIG. 3, the removable base 17a is in the form of a truncated cone 23, surrounded by an annular crown 24, applied against the crown 3 of the frame 1. The annular crown 24 has approximately the same diameter B as that of the rotor and the lower end of the frusto-conical portion 23 has a smaller dimension, serving as a central circular opening of diameter A through which the gaseous fluid enters the hood. The height of this truncated cone is such that its side walls form an angle of about 30 ° with the base. This removable bottom acts as a replacement for the aerodynamic seal 20 (Fig. 2) by providing a turbulence chamber under the rotor favorable for the deposition of impurities on the surface of the rotor. The diameter A of the central circular opening must be equal to or less than 0.75 times the diameter B of the annular crown 24.

At the upper part of the hood against the annular ring 2 is placed a conventional filter 21 intended for example to chemically neutralize gaseous toxic particles contained in the fluid to be purified or to neutralize unpleasant odors or else to retain any particle which would not have not attached to the pleated rotor.

• Pour mettre la hotte en fonctionnement, on met en marche le moteur 5, qui met en rotation le disque plissé 13. Lorsqu'il est en rotation, le disque plissé 13 fonctionne comme l'hélice d'un ventilateur, c'est-à-dire qu'il crée une circulation du fluide à épurer à travers la hotte. Le fluide gazeux à épurer est par conséquent aspiré à travers l'ouverture 18 du fond 17, passe le long des surfaces du disque plissé 13 sans les traverser selon la ligne indiquée en 22, traverse les ouïes 8 aménagées dans la plaque 4 supportant le moteur 5 pour se répartir ensuite dans l'espace ménagé sous le filtre conventionnel 21. Le rotor ou disque plissé 13 provoque un brassage du fluide gazeux à épurer et entraîne le dit fluide dans la hotte selon un flux turbulent. Ce flux turbulent s'avance le long des plis du disque plissé sans les traverser et arrive au contact avec la surface rugueuse du dit disque où les particules solides et liquides sont retenues par adsorption. Le disque plissé ou rotor 13 a donc en plus de sa fonction de ventilation une fonction d'épuration par la rétension des particules solides et liquides qui se fixent sur sa surface rugueuse. Le rotor peut donc se charger d'impuretés sans perdre son efficacité et le fluide partiellement épuré, en particulier épuré des particules solides et liquides, peut traverser le filtre conventionnel 21 selon la flèche 22, sans boucher le dit filtre 21, qui sera en général un filtre choisi pour épurer chimiquement le fluide. Il pourra donc être imprégné de substances chimiques adéquates choisies en fonction des gaz que ces substances sont sensées neutraliser ou fixer. L'avantage de la hotte qui vient d'être décrite réside dans la combinaison des deux filtres, c'est-à-dire le rotor plissé adsorbant destiné à réaliser la première épuration des polluants liquides et solides, et un deuxième filtre conventionnel qui pourra lui être traversé sans risque d'être trop rapidement bouché puisque la première épuration a déjà été réalisée à l'aide du rotor 13.

The gaseous fluid purification hood which has just been described with reference to FIGS. 1 and 2 works as follows:

• To put the hood into operation, the motor 5 is started, which rotates the pleated disc 13. When it is rotating, the pleated disc 13 operates like the propeller of a fan, that is to say say that it creates a circulation of the fluid to be purified through the hood. The gaseous fluid to be purified is consequently sucked through the opening 18 of the bottom 17, passes along the surfaces of the pleated disc 13 without crossing them along the line indicated at 22, crosses the gills 8 arranged in the plate 4 supporting the motor 5 to then be distributed in the space provided under the conventional filter 21. The rotor or pleated disc 13 causes stirring of the gaseous fluid to be purified and drives said fluid in the hood in a turbulent flow. This turbulent flow advances along the folds of the pleated disc without passing through them and comes into contact with the rough surface of said disc where the solid and liquid particles are retained by adsorption. The pleated disc or rotor 13 therefore has, in addition to its ventilation function, a purifying function by retaining solid and liquid particles which are fixed on its rough surface. The rotor can therefore be loaded with impurities without losing its efficiency and the partially purified fluid, in particular purified from solid and liquid particles, can pass through the conventional filter 21 according to arrow 22, without clogging the said filter 21, which will generally be a filter chosen to chemically purify the fluid. It may therefore be impregnated with suitable chemical substances chosen as a function of the gases which these substances are deemed to be neutral. read or fix. The advantage of the hood which has just been described lies in the combination of the two filters, that is to say the pleated adsorbent rotor intended to carry out the first purification of liquid and solid pollutants, and a second conventional filter which may pass through it without risk of being too quickly blocked since the first purification has already been carried out using the rotor 13.

The fixed aerodynamic seal 20 placed between the rotor 13 and the suction hole 18 has a particularly important function. As mentioned above, it partially covers the periphery of the rotor 13 (approximately 4 of the radius of the rotor 13), without however touching said rotor. This seal 20, usually made of the same material as the rotor 13 is interchangeable like it, it prevents the backflow of the air sucked in and it thus allows a certain pressure to be obtained inside the hood, which forces the fluid gas through the conventional filter 21 and out of the hood with a satisfactory flow.

This fixed aerodynamic seal 20 is pleated, the folds being placed radially relative to the suction hole, without touching the rotor 13. This fixed pleated seal can also be replaced by a series of straight or V or S folded strips or any another form opposing the discharge of the fluid towards the outside of the hood.

A prototype of the hood which has just been described with reference to FIGS. 1 and 2 were produced for an application of an air recirculation kitchen hood. This prototype was made in official standards of existing hoods and has been tested. It was equipped with a 90 watt, 220 volt motor to drive an adsorbent rotor with an outside diameter of 400 mm rotating at variable speeds between 500 and 1,200 rpm. The aerodynamic seal 20 had an inside diameter of 350 mm and an outside diameter of 400 mm. The air entered the hood at a speed of approximately 2 m / second, and the hood had a flow rate of 600 m ³ per hour. The filter 21 consisted of an agglomerated activated carbon bed with a capacity of 3 liters on a surface of 0.22 m ² placed at the top of the hood. It ensured a complete deodorization of the cooking vapors so that there was no longer any inconvenience in letting the air escape into the kitchen. The purification of the liquid and solid parts (water vapors, soot, grease, etc.) was carried out by means of the pleated rotor 13 and the aerodynamic seal 20 made of interchangeable blotting paper.

The lower opening 18 of the hood makes it possible to see the pleated rotor 13 and the dynamic seal 20. It is thus possible to check at a glance the degree of fouling of the rotor and the seal, which can then be replaced by standard exchange when it is at saturation, that is to say when its folds are filled with dust and fat. This operation should not take place more than three or four times a year in the normal use of a hood for a private housewife. Since the rotor is made of a paper-based material, its destruction poses no problem.

Flammability tests of this rotor, not protected against fire above a fryer or of a kitchen stove, were carried out and showed that when the rotor is in motion the flames which reach it cannot communicate the fire to the hood. Rotation of the rotor prevents the flame from igniting its surfaces, however saturated with grease they may be. During the tests which were carried out, it was impossible to set the rotor on fire. This fact is a considerable advantage, because in conventional hoods provided with metallic fire-resistant grates, these quickly clog up, they must be washed frequently under penalty of a significant reduction in the flow of aspirated air.

At equal air flow, the hood which has just been described with its 90 watt motor implements a lower power than that which is necessary to overcome the pressure drops produced through the conventional filters which equip the hoods of the prior art and which gradually become blocked.

The hood which has just been described can also be used to humidify the air. It will then suffice to add a vaporizing device or simply to humidify a filter such as the filter 21 and to operate the hood which has the advantage of being able to dust and disinfect the air before its humidification without having to change or constantly wash clogged filters, as is the case in prior art devices.

Another embodiment was carried out to purify the ambient air of an autogenous soldering station. In this example, the soot particles were fixed on the rotor while the metal oxides were neutralized by the filter 21. The purification of the welding fumes being total, it is no longer necessary to exhaust the air outside, which represents a serious saving of heat energy and investment.

The release of styrene vapors when making molded parts made of polyester reinforced with glass fibers is harmful. Face masks with activated carbon filters are unpleasant to wear and quickly blocked by glass fibrils. The production and installation of a hood according to the present invention made it possible to collect dust, glass fibers and styrene aerosols on the rotor 13 and to neutralize the styrene vapors with the active carbon filter 21. a yield greater than 90%. The air thus purified can be recycled in the workshop without inconvenience.

Other tests have been carried out in medical and hospital applications. By operating a hood similar to that described in fig. 1 and 2, it was found that it was possible to rapidly lower the rate of bacterial contamination of a room and to keep it within acceptable standards of permanent contamination, while neutralizing odors by an activated carbon filter.

In the embodiments mentioned above, a pleated rotor has been shown and described forming a "sun pleated" consisting of folds starting from a center and moving away radially towards the periphery of the rotor. It is obvious that this pleated rotor can be replaced by other rotors similar for example to the embodiments described in the previous patents, in particular a pleated rotor made up of several stages or a rotor made up of channels established between two plane discs. As a variant, any rotor which has parts of alternating left surfaces or parts of plane surfaces forming angles therebetween and arranged to produce a turbulent flow of gaseous fluids which they move is more or less effective, it being understood that the rotor surfaces must be rough to retain and fix solid and liquid particles. The same applies to the fixed aerodynamic seal placed between the rotor and the gaseous fluid suction hole in the hood.

It was said above that the filter 21 could be soaked with water by means of a suitable device and that the hood could serve as a humidifier for a living room, it being understood that the humidified air was previously purified by the action of the rotor.

As a variant, the filter 21 can also be impregnated with a perfume or a deodorant intended to neutralize odors or else be soaked with a germicidal agent.

The filter 21 can also be formed from a solid honeycomb body, conditioned in temperature to heat or cool the flow leaving the hood. This device becomes a complete air conditioner since it is able to purify the ambient air of its solid, liquid and gaseous pollutants, to humidify or dry the purified air, to heat or cool it at will. This succession of operations is carried out almost noiselessly and without deploying excessive energy.

Claims (14)

1. Purification hood for gaseous fluids comprising an external frame, a motor driving a rotor, characterized in that the rotor is arranged to simultaneously generate a ventilation function and a purification function for solid and liquid pollutant particles in suspension in the fluid to be purified by adsorption on rough surfaces which constitute it, the rotor being followed by a filter arranged to neutralize or transform the particles of undesirable gaseous components contained in said fluid after the purification due to the rotor. 2. Purification hood according to claim 1, characterized in that an aerodynamic anti-backflow element is placed in the inlet opening of the gaseous fluid in the hood. 3. Purification hood according to claim 2, characterized in that the aerodynamic anti-backflow element of the gaseous fluid drawn into the hood is a folded strip forming a serpentine surrounding the inlet opening of the hood. 4. Purification hood according to claim 2, characterized in that the aerodynamic anti-backflow element of the gaseous fluid sucked into the hood is a cover having a frustoconical part with a central opening. 5. Purification hood according to claim 5, characterized in that the rotor is arranged with left surfaces and / or flat surfaces forming angles between them so as to produce a turbulent flow around its surfaces and force said flow to lick its surfaces without crossing them. 6. Purification hood according to claim 1, characterized in that the filter placed at the outlet of the hood consists of fibrous material, agglomerated or granulated, traversed by the gaseous fluid drawn into the hood by the rotor. 7. Purification hood according to claim 6, characterized in that the filter through which the gaseous fluid passes is impregnated with a reagent capable of transforming particles of undesirable gaseous components contained in said fluid. 8. Purification hood according to claim 6, characterized in that the filter placed at the outlet of the hood consists of granulated activated carbon. 9. Purification hood according to claim 7, characterized in that the reagent is a chemical agent. 10. Purification hood according to claim 7, characterized in that the reagent is water. 11. Purification hood according to claim 7, characterized in that the reagent is a perfume or a deodorant agent. 12. Purification hood according to claim 7, characterized in that the reagent is a germicidal agent. 13. Purification hood according to claim 1, characterized in that the rotor is a pleated disc. 14. Purification hood according to claim 4, characterized in that the diameter of the central opening of the frustoconical cover is equal to or less than 0.75 times the diameter of the frustoconical part of said cover.

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