CH637307A5 - GAS FLUID PURIFICATION HOOD. - 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 purification hood comprising an external frame, a motor driving a rotor and at least one purification member traversed by the gaseous fluid entrained through the hood by the rotor.

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 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. Similarly, in the second case, the electrodes must be cleaned frequently, otherwise the electrical circuit will fail or the production of harmful gases.

In the use of hoods, for example for domestic use in kitchens, it is usual to provide at the entrance of the hood a metal fire screen which is very quickly fouled by the deposit of soot, oil droplets , etc. By this fouling, the free effective section available to the gaseous fluid is much reduced, and the grid must be washed very frequently so that the filter retains its efficiency which depends, as we know, on the gas flow passing through it.

The object of the invention is to remedy these drawbacks and to propose a hood which has other advantages and which can work in a closed circuit, that is to say in which the air is so clean that '' it can be recycled in the room. Another object of the invention is to provide a hood in which the filters are not too quickly clogged, and which continues to operate satisfactorily even in the case where the filters are not replaced normally.

The hood according to the invention is characterized in that the rotor is placed at the inlet of the hood and is arranged to simultaneously generate a ventilation function and a purification function by an arrangement of alternate left surfaces, and / or parts of planar surfaces forming angles therebetween, so as to produce a turbulent flow of gaseous fluid which they move and to force said fluid to lick without passing through said surfaces, which have a rough configuration capable of retaining solid particles and liquids 20 contained in the fluid to be purified, the rotor being followed by a filter through which the fluid passes before leaving the hood.

According to a preferred embodiment, the rotor is placed above an inlet opening of the hood, an aerodynamic anti-backflow seal being placed in the inlet opening, near the rotor, so as to s '' spread over part of the periphery of the rotor without touching it. In this preferred embodiment, the rotor is made in the form of a sun pleated and the aerodynamic seal is made from a folded strip forming a serpentine surrounding the inlet opening of the hood.

In the hood according to the invention, the ventilating action of the rotor, which forces the flow to lick without passing through the rough surfaces of said rotor, irreversibly causes the deposition of solid and liquid impurities on the surfaces of the rotor . As the rotor is placed above the inlet opening of the hood, its central part 35 is visible and its degree of fouling is at all times controllable at a glance. The pressure losses on suction in the hood according to the invention are almost zero, because the flow of the fluid to be purified enters the hood freely as soon as the rotor is rotated. This results in the possibility of using very low fan powers, lower speeds and much less noise, at equal flow rate, if a comparison is made with traditional hoods which purify by means of filters traversed by the flow. gaseous fluids. The aerodynamic seal placed at the inlet of the hood prevents the discharge of gaseous fluid through the suction port of the hood. The filter placed at the outlet of the hood is usually a filter impregnated with a chemical reagent capable of neutralizing particles of undesirable gaseous components contained in the fluid to be purified. It is obvious that, by choosing appropriate chemical reagents to impregnate the filter placed at the outlet of the hood, it is possible to chemically neutralize the gases which are not retained by the rotor working by adsorption, that is to say say by fixing solid and liquid particles on its surface.

The purification of the gaseous fluid through the hood which is the subject of the present invention therefore takes place in two operations: firstly the retention on the rough surfaces of a rotor adsorbing solid particles (dust, soot, fibers, pollens, etc.) and liquids (aerosols, oil particles, water vapor, mist, etc.), then chemical neutralization of harmful gases or odors by a traditional filter chemically treated for this purpose. The purification of the gaseous fluid 60 being complete, the recycling of the fluid into the ambient air, immediately after leaving the hood, no longer presents any drawbacks.

The hood according to the invention is light and compact. It is independent of any pipe and only requires a low-voltage single-phase socket for its power supply. By allowing the purified fluid to be recycled in the ambient air, this hood does not cause any loss of heat energy in the room in which it is installed. The filter placed at the outlet of the hood does not

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It is almost never dirty, since the particles which usually foul the filters of the hoods of the prior art are retained on the adsorbent rotor. This has the consequence that the hood has, in operation, a lifetime much longer than that of traditional hoods.

The drawing shows, by way of example, an embodiment of a gaseous fluid purification hood according to the invention.

In the drawing:

fig. 1 shows a perspective view from below of an embodiment of the purification hood, and FIG. 2 a section through the hood according to line II-II of FIG. 1.

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, two annular rings 2 and 3 (fig. 2) which will serve as support for retaining the internal parts of the hood described below. 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 inner surface of the circular frame 1. The rings 2, 3 and the plate 4 are fixed to the frame 1 by welding, as well 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 circular mantle 1 in the case where the hood is produced by molding. The hood casing formed 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 secured to 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; the pleated disc is held on the plate 14 at its periphery by any known means such as gluing, 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 of 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 is 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 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 to be fixed, for example staples, snaps, or Velcro® supports.

A removable bottom 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 is removably fixed 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 pleated strip whose two ends are joined to form the aerodynamic seal 20. The joint 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 the removable base 17 has been removed.

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, to neutralize unpleasant odors, or to retain any particle that would not have attached to the pleated rotor.

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 distribute itself in the space provided under the conventional filter 21. The pleated rotor or 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 retention function for solid and liquid particles which are fixed on its rough surface. The pleated rotor 13 therefore performs a purification function without being crossed by the fluid to be purified. It can therefore clog without losing its effectiveness. The partially purified fluid, in particular purified from solid and liquid particles, can then pass through the conventional filter 21, according to arrow 22, without clogging said filter 21 which will generally be a filter chosen to chemically purify the fluid. It can therefore be impregnated with suitable chemical substances chosen according to the gases which these substances are supposed to neutralize or fix. The advantage of the hood which has just been described resides in the combination of the two filters, that is to say the pleated adsorbent rotor intended to carry out the first purification of liquids and solids, and a second traditional filter which can be crossed 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 'A 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 sucked air and it thus allows to obtain a certain pressure, inside the hood, which requires the gaseous fluid to pass through the conventional filter 21 and to leave the hood with a satisfactory flow rate.

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 other form opposing the discharge of fluid to the outside of the hood.

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A first 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 first prototype was produced in the official standards for the size of current hoods and was tested. It was equipped with a 90 W, 220 V 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 about 2 m / s, and the hood had a flow rate of 600 m3 / h. The filter 21 consisted of an agglomerated activated carbon filter, with a capacity of 31 on a surface of 0.22 m2, 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 vapor, soot, grease, etc.) was carried out by means of a pleated rotor 13 and an 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 saturated, 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 unprotected fire rotor, above a fryer or a kitchen stove, have been carried out and have shown that when the rotor is in motion the flames reaching it do not can communicate the fire to the hood. Rotation of the rotor prevents the flame from igniting its surfaces, as saturated with grease as they are. 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 W motor implements a lower power than that which is necessary to overcome the pressure losses produced through the traditional 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 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 it is humidified without it being necessary to constantly change or wash clogged filters, as is the case in the devices of the prior art.

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 evacuate the air to the exterior, 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 by the activated carbon filter 21. with 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 above-mentioned embodiments, a pleated rotor has been shown and described forming a sun pleat 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 Swiss patent N ° 609880, in particular a pleated rotor made up of several stages or a rotor made up of channels established between two flat 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 displace is more or less suitable, being it is understood that the surfaces of the rotor must be rough in order 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. In the embodiment of fig. 1 and 2, this aerodynamic seal is pleated, the folds being placed radially relative to the suction hole, without touching the rotor. This fixed pleated seal can also be replaced by a series of straight or bent Y or S-shaped strips, or any other form preventing the discharge of the fluid towards the outside of 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 alternatively be formed from a solid honeycomb body, conditioned in temperature to heat or cool the air flow leaving the hood.

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Claims (11)

637,307 1. Purification hood for gaseous fluids, comprising an external frame, a motor driving a rotor and at least one purification element traversed by the gas flow driven through the hood by the rotor, characterized in that the rotor is placed at the entrance of the hood and is arranged to simultaneously generate a ventilation function and a purification function by an arrangement of alternate left surfaces, and / or parts of plane surfaces forming angles between them, so as to produce a turbulent flow of the gaseous fluid which they displace and forcing said flow to lick without passing through said surfaces, which have a rough configuration capable of retaining the solid and liquid particles contained in the fluids to be purified, the rotor being followed by a filter crossed by the fluid before leaving the hood. 2. Purification hood according to claim 1, characterized in that the rotor is placed above an inlet opening of the hood, an aerodynamic anti-backflow seal being placed in the inlet opening, near the rotor, so as to extend over part of the periphery of the rotor without touching it. 2 3. Purification hood according to claim 1, characterized in that the rotor is made in the form of a sun pleated. 4. Hood according to claim 2, characterized in that the aerodynamic seal is produced from a folded strip forming a serpentine surrounding the inlet opening of the hood. 5. Purification hood according to claim 1, characterized in that the filter placed at the outlet of the hood is a filter impregnated with a reagent capable of neutralizing particles of undesirable gaseous components contained in the fluid to be purified. 6. Purification hood according to claim 5, characterized in that the reagent is activated carbon. 7. Purification hood according to claim 5, characterized in that the reagent is a chemical agent. 8. Purification hood according to claim 1, characterized in that the filter placed at the outlet of the hood is soaked with a germ-ciding agent. 9. Purification hood according to claim 1, characterized in that the filter placed at the outlet of the hood is soaked with a perfume. 10. Purification hood according to claim 1, characterized in that the filter placed at the outlet of the hood is soaked with water. 11. Purification hood according to claim 1, characterized in that the filter placed at the outlet of the hood is a solid cellular body.