WO2022122462A1 - Device and method for depolluting air from confined or semi-confined environments - Google Patents

Abstract

The present invention relates to a device for removing particles and polluting gaseous compounds from a gas stream (F1, F2) from the air present in a confined or semi-confined environment, comprising an arrangement consisting of a plurality of enclosures (10, 20, 30) arranged in series, each enclosure (10, 20, 30) comprising openings (11, 21, 31) provided to allow the gas stream to pass through the arrangement from one side to the other, and each enclosure comprising at least means (50, 60, 61) for generating turbulent flow areas and non-turbulent flow areas of said gas stream (F1, F2). In addition, the arrangement of enclosures (10, 20, 30) comprises at least: a first enclosure (10) comprising means for controlling humidity (13, 13') of the gas stream, a second enclosure (20) comprising means (23, 24) for the photooxidation and/or photocatalysis of the polluting gaseous compounds, a third enclosure (30) comprising means for adsorbing and/or absorbing the polluting gaseous compounds. The invention further relates to a method for removing particles and polluting gaseous compounds from a gas stream from the air present in a confined or semi-confined environment.

Description

DEVICE AND METHOD FOR DEPOLLUTING THE AIR IN CONFINED OR SEMI-CONFINED ENVIRONMENTS

Technical area

The invention is concerned with the treatment of air in confined or semi-confined spaces, such as parking lots for underground vehicles, road or even railway tunnels, but also individual dwellings, work spaces, or still spaces intended to accommodate young children (nurseries, schools, etc.).

Particularly in the case of underground transport networks of the rail type, these confined or semi-confined spaces include stations, corridors, trains, tunnels, commercial premises, technical rooms and train repair centers.

In general, these spaces can be frequented by a transient population, users, and/or by a more or less permanent population, such as operating personnel or shopkeepers.

The Indoor Air Quality Observatory (OQAI) estimated in a study that today we spend on average 80% of our time in closed environments. However, this same organization showed, in a study conducted between 2003 and 2005, that the air inside homes generally has higher concentrations of Volatile Organic Compounds (VOCs) than the air outside. More specifically, it has been shown that 18 of the 20 VOCs measured are in higher concentrations indoors than outdoors and that almost a quarter of homes would exceed the European guide values, in particular with regard to formaldehyde and toluene. . However, it was shown in the 1990s the existence of a relationship between asthma and high levels of VOCs.

In parallel with VOC emissions, a second component in its own right of the problem of atmospheric pollution is that of the depollution of dust, in particular particles with characteristic dimensions of 10, 5, 2.5 or 1 pm (commonly denoted PM10, PM5, PM2.5, PM1 respectively) with an even greater challenge regarding the capture of the smallest particles. Indeed, the trapping of these fine particles is of an even more worrying interest knowing that it is these smallest particles which penetrate deep into the respiratory tree.

In these various confined or semi-confined places, ventilation and extraction and/or air blowing systems are generally installed, the purpose of which is to improve the quality of the air, by renewing it by the blown "fresh" air taken from outside and/or by extraction and discharge of stale air to the outside. In some cases, polluted air is depolluted in so-called “bypass” installations, the air being extracted, depolluted, then reinjected.

However, these systems are insufficient to guarantee correct air quality in these confined spaces. For example, for metro-type rail networks, we sample urban outdoor air to renew the air. However, urban air may already have a significant level of pollution, particularly in terms of fine particles and polluting gaseous compounds such as NOx, or other polluting compounds such as VOCs, or sulfur derivatives such as sulfur oxides SOx, in particular because of car traffic, urban heating, or nearby industrial activities.

As for confined spaces such as road tunnels or car parks, where the air is loaded with particles and polluting gases due to underground road traffic, this polluted air is extracted to be discharged outside, thus polluting the outside atmosphere close to these confined spaces.

Whether the pollutants are emitted in the confined spaces mentioned above, or reintroduced from the outside, they can be classified into two categories:

- particles, which generally come from imperfect combustion (soot), but also from the wear of tires or vehicle braking components, or quite simply from the degradation of road surfaces (dust). Their small size, of the order of a few microns, explains their maintenance in suspension in the air. For underground railway enclosures (EFS), the major constituents identified are different metals including iron, elemental carbon and organic carbon. It is also possible to add terrigenous dust, in particular composed of silica.

- gaseous compounds, essentially nitrogen oxides, with NOx including monoxide and/or nitrogen dioxide (NO, NO ₂ ), but also carbon monoxide CO, sulfur derivatives and VOCs. Note that NO can spontaneously oxidize to NO ₂ under the effect of sunlight and the presence of oxygen, so even if it is potentially less harmful than NO ₂ at equal concentrations, it is also potentially a precursor of NO ₂ .

There is therefore a real need to treat the air arriving in and/or extracted from these confined spaces, to improve the quality of the air in these spaces, and/or the air in their vicinity.

Prior technique In general, concerning the capture of particles, processes are known using physical filters (that is to say with frontal steric selectivity, such as for example sieves), electrostatic (that is to say using a additional energy for a change of state of molecules in the gas phase to promote electrostatic interactions), or even via the use of solid adsorbents (such as, for example, beds of activated carbon and other molecular sieves of the zeolite type).

The main disadvantage of physical filters is that they become dirty over time. If this fouling can prove beneficial for the capture of the smallest particles (their porosity decreases with fouling, which makes them more and more selective towards the smallest particles), the pressure drops and the gas velocities are see them strongly modified resulting in a loss of overall performance. It is then necessary to regenerate the filter medium.

In road tunnels, for example, electrostatic filtration devices have already been considered to trap solid particles, the aim being in fact to improve visibility in the tunnels more than to clean up the atmosphere before discharge into the atmosphere. 'outside. As the airflows are often high, from a few tens to a few hundreds of m ³ per second, and the concentrations of pollutants very low, of the order of a milligram per m ³ or less, the devices most often used are electrostatic precipitators for particulate pollutants and chemical traps on absorbent surfaces for gaseous pollutants, so as to minimize the pressure drop of the air circulation. The results are often disappointing, especially for particles which can also “poison” chemical traps and render them ineffective. However, their handling is complex, because they are operated under high voltage. Moreover, such a technology is limited to the capture of ionizable particles and more particularly of metallic elements. In addition, the particle ionization step, an essential prerequisite for their electrostatic precipitation, produces nitrogen dioxide (NO2) by reaction of NO with the ozone (O3) produced in the ionizer, which is an induced effect. harmful.

Patent application EP 0 431 648 is also interested in the treatment of air in confined spaces, in particular offices or hospitals, by proposing ozone treatments with oxidation catalysts to eliminate VOCs and biological pollutants, with the disadvantages associated with the use of ozone highlighted above.

Gas/liquid technologies are also known, such as spray, tray or bubble columns, for example. One can for example use various solvents allowing strong interactions between the gaseous pollutants (such as for example the VOC, the NOx) but also between the particles in suspension. However, this technology is only possible with the use of heavy circulation means (liquid pumps, compressors, tanks), calibrated, requiring the immobilization of a large volume of liquid and therefore a large footprint. In addition, the internal contactors are expensive. Finally, the degradation and/or capture of gaseous pollutants under such conditions very often requires the use of a fixed bed with a crossing or licking flow to allow their capture or reduction, which can lead to a pressure drop. In addition, this technology uses solvents that can be corrosive and even dangerous.

We also know the application WO 2019/192827 A1 which relates to a method and a device for treating air in a confined space to deplete it of polluting gaseous compounds and solid particles. More specifically, at least part of the air to be treated is led into a washing device in contact with a flow of a liquid effluent comprising at least one compound which is active with respect to the or at least one of the polluting gaseous compounds, so that the liquid effluent in contact with the air to be treated becomes charged with particles and acts on said gaseous compound, for example by absorption, then optionally by chemical conversion, in particular of the oxidation or reduction type. However, this device has the following disadvantages: toxicity of the capturing agents, greater potential environmental impact if leakage of dangerous product or evaporation for example, management of complex fluids and pipe network (more or less dangerous especially if under pressure), investment in pump for liquids necessary, investment all the more important if corrosive product (acid and/or basic product), gas/liquid transfer to be controlled. In addition, this system has limited modularity (multi-chemical and/or delicate physical absorption for the same mixture) and requires drying out the outgoing air to maintain a final humidity level consistent with the discharge environment (otherwise there is a risk of promote the development of fungi and bacteria). Finally and in particular for aqueous solvents, consumption of mostly clean water.

In the field of particle filtration only, filters of the TFP type ("Turbulent Flow Precipitator" in English, and "Précipitateur à Flux Turbulent" in French) are also known, for example described in the following documents: EP 0626880 A1 ( US 5626651), EP0755294 B1 (US2003188636A), EP0851785 A2 (US6007593A). The general principle of these filters consists in generating a zone with turbulent flows (gas speed of the order of 10 to 50 m/s) and an adjacent zone made up of calm spaces. Turbulence makes it possible to increase the probabilities of particles passing near calm zones, where they can sediment and/or be captured on collecting surfaces. The collected particles can be removed continuously or cyclically. In particular, document EP 0626880 A1 (US 5626651) describes a device making it possible to eliminate particles contained in a current of fluid, by creating a turbulent flow. More specifically, this device comprises a vein in which the flow flows, and a series of parallel plates spaced a few centimeters apart, arranged at the base of the flow in a perpendicular manner. These plates generate vortices in the main flow of the vein, which come to "die" in a calm zone, behind the plates, the particles then settling on the surfaces of the plates.

Document EP0755294 B1 (US2003188636A) is also known, which describes improvements to the device described in document EP 0626880 A1 (US 5626651), in particular different geometries of the vein (rectangular, annular, spiral, etc.), and plates which may include porous ceramic materials or fiber fabrics to retain fine particles

Document EP0851785 A2 (US6007593A) is also known, which describes an agglomeration device intended to increase the size of fine particles suspended in a turbulent gas stream, in order to improve their trapping.

This type of filter does not require a particular energy input (unless it is necessary to control the flow at the inlet of these filters) unlike the electrostatic filters or the gas/liquid contactors described above. On the other hand, this type of filter, as described in the prior art, does not allow the filtration of polluting gaseous compounds, such as VOCs and NOx. In addition, devices of the TFP type according to the prior art are effective for particles having a particle size greater than 1-2 microns, and this with efficiencies between 80 and 90%. When the particle size becomes lower than this range of 1-2 microns, the capture efficiency drops rapidly to around 30/40%.

The object of the invention is therefore to remedy these drawbacks by proposing a new device and a new method for treating the air of confined spaces, which is effective both with respect to pollutants in the form of particles and in form of gaseous compounds. Moreover, the device according to the invention being composed of juxtaposed enclosures having their own function, the device can be modulated according to the pollutants specific to each confined environment to be treated. In addition, the implementation and maintenance of this filter are facilitated. Finally, the method according to the invention does not require any particular energy input, unlike the filters according to the prior art, in particular the electrostatic filters or the gas/liquid contactors described above.

Summary of the invention

The present invention relates to a device for eliminating particles and polluting gaseous compounds from a gas flow coming from the air present in a confined or semi-confined environment. confined, said device comprising an arrangement formed by a plurality of enclosures arranged in series, said enclosures comprising openings arranged to allow passage of said gas flow on either side of said plurality of enclosures arranged in series, each enclosure comprising at least means for generating turbulent flow zones and non-turbulent flow zones of said gas flow in said enclosure.

According to the invention, said arrangement comprises at least:

- a first enclosure comprising means for controlling the humidity of said gas stream;

- a second enclosure comprising means for photo-oxidation and/or photo-catalysis of said polluting gaseous compounds of said gas stream;

- A third chamber comprising means for adsorption and/or absorption of said polluting gaseous compounds from said gas stream.

According to an implementation of the invention, said means for generating turbulent flow zones and non-turbulent flow zones of said gas flow from at least one of said enclosures may comprise a plurality of rows and/or a plurality of columns of plates arranged perpendicular to said gas flow and on the base of said at least one enclosure.

According to an implementation of the invention, said means for generating turbulent flow zones and non-turbulent flow zones of said gas flow from at least one of said enclosures may comprise a plurality of rows of plates arranged perpendicularly to said gas flow and on the base of said at least one enclosure, each of said plates comprising a plurality of openings in the form of diaphragms.

According to one implementation of the invention, said device may comprise means for controlling the arrangement of said means for generating turbulent flow zones and non-turbulent flow zones of said gas flow from at least one of said enclosures, in particular the position and/or the inclination and/or the orientation of said means for generating turbulent flow zones and non-turbulent flow zones of said gas flow.

According to one implementation of the invention, said means for controlling the humidity of said gas stream from said first enclosure may comprise means for circulating a heat transfer fluid in said first enclosure.

According to one implementation of the invention, said photo-oxidation and/or photocatalysis means of said second enclosure may comprise at least one light source, preferably a UV lamp, and bodies coated with a photo-active phase . According to one implementation of the invention, said adsorption means of said third enclosure may comprise bodies coated with an adsorbent material or a fixed bed of granules.

According to one implementation of the invention, said absorption means of said third enclosure may comprise bodies coated with an absorbent material, a fixed bed of granules or means for dispersing an absorbent solvent.

According to one implementation of the invention, said arrangement may be formed by said first enclosure, said second enclosure and said third enclosure arranged in series and in this order along said gas flow.

The invention further relates to a method for eliminating polluting particles and gaseous compounds present in the air of a confined or semi-confined medium comprising at least the following steps: a) conducting, in the form of a flow gaseous, at least part of the air of said confined or semi-confined medium in at least one device for removing at least particles from a gas stream originating from the air present in a confined or semi-confined medium as described above ; b) said particles and said polluting gaseous compounds are eliminated from said gas stream by means of said at least one device.

Other characteristics and advantages of the device and of the method according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the appended figures and described below.

List of Figures

FIG. 1 schematically presents a non-limiting embodiment of the device according to the invention.

FIG. 2 schematically presents a non-limiting embodiment of the first enclosure of the device according to the invention.

FIG. 3 schematically presents another non-limiting embodiment of the first enclosure of the device according to the invention.

FIG. 4 schematically presents a non-limiting embodiment of the second enclosure of the device according to the invention. FIG. 5 schematically presents a non-limiting embodiment of the third enclosure of the device according to the invention.

FIG. 6 illustrates dimensions of a non-limiting embodiment of one of the enclosures of the device according to the invention.

Description of embodiments

According to a first aspect, the invention relates to a device for removing particles and polluting gaseous compounds from a gas flow coming from the air present in a confined or semi-confined environment.

According to a second aspect, the invention relates to a method for removing particles and polluting gaseous compounds from a gaseous flow coming from the air present in a confined or semi-confined environment.

By confined environment, respectively semi-confined, is meant an enclosed space, respectively partially enclosed, such as car parks for underground vehicles, railway or road tunnels, individual dwellings, work spaces (office, workshop, garage, cabinetmaking, etc.), or spaces intended to accommodate young children (nurseries, schools, etc.).

By particles is meant any solid or liquid body with a size of less than 100 μm, optionally with a volatile phase (for example of the hydrocarbon type) which can be adsorbed on a solid phase. In a non-limiting way, the particles according to the invention can correspond to soot particles which are fine particles rich in PAHs (polycyclic aromatic hydrocarbons), but also particles resulting from the abrasion of parts such as for example metal particles resulting brake pads, particles from tire abrasion, but also pollen, etc.

According to the invention, the air to be treated comes from a confined or semi-confined environment and enters the device according to the invention in the form of a gas stream, that is to say that the air to be treated enters the device according to the invention with a non-harmful flow and speed. Advantageously, the speed of the gas stream is greater than 0.2 m/s, preferably greater than 0.4 m/s and the flow rate of the gas stream is greater than 200 m ³ /h, preferably 255 m ³ /h. These speeds and flow rates are conventional at the outlet of air extraction and/or ventilation means for confined or semi-confined environments. Concretely, these means are in the form of networks of pipes, chimneys and various enclosures in fluidic connection with each other and equipped with ad hoc fans/extractors to ensure the circulation of air from the inside to the outside of the confined space and/or vice versa. By arranging the device according to the invention at the outlet of these ventilation/extraction means, the gas flow to be treated is caused to circulate in the device according to the invention, possibly without even having recourse to additional devices. Alternatively, if such ventilation/extraction means do not exist in situ or are difficult or impossible to access, the device can also comprise its own ventilation means to ensure the supply and circulation of the gas flow in the device.

The device according to the invention comprises an arrangement of juxtaposed enclosures (or else arranged in series), said enclosures comprising openings arranged to allow the passage of the gas flow on either side of the arrangement of juxtaposed enclosures. In other words, each enclosure has openings to allow the gas flow to enter the enclosure, and openings to allow the gas flow to leave the enclosure, the outlet/inlet openings of an enclosure being able to communicate with entry/exit openings of another speaker in the speaker arrangement. In this way, the air is partially treated in one enclosure, then passes into the next enclosure (depending on the direction of the gas flow) of the arrangement to continue the treatment. The enclosures according to the invention can be parallelepipedic, cylindrical or of any other shape.

According to the invention, each enclosure comprises means for generating turbulent flow zones and non-turbulent flow zones of the flow in the enclosure, when the latter is traversed by the gas flow. By turbulent flow, we mean a flow in which the speed has a whirling character. In particular, the size, location and orientation of the vortices of a turbulent flow constantly vary. Turbulent flows are therefore characterized by a very disordered appearance, a behavior that is difficult to predict and the existence of numerous spatial and temporal scales. Hereafter and for purposes of simplification, reference is made to means for generating zones of differentiated flow or alternatively means for generating a differentiated hydrodynamic flow.

Thus, according to the invention, each enclosure comprises means for generating zones of differentiated flow, more precisely, first zones in which the flow is of the turbulent type and second zones without turbulent flow. In the first zones, the gaseous flow flows in a turbulent way, carrying the particles in suspension as well as the polluting gaseous compounds. The vortices will also penetrate into the second zones in which the turbulence disappears, and where the fine particles and/or the polluting gaseous compounds, carried away by these vortices, will be able to be captured as described below, according to the characteristics specific to each pregnant. These second zones are also called collector assistant zones in turbulent flow precipitators according to the prior art.

Thus, according to the invention, the polluting particles and/or gaseous compounds are carried away by vortices formed in the turbulent flow zones towards the non-turbulent flow zones, and are captured in the non-turbulent flow zones. The differentiated flow according to the invention makes it possible to increase the probability of interactions between the particles and/or the polluting gaseous compounds and the means specific to each enclosure to capture the particles and/or the polluting gaseous compounds.

According to one implementation of the invention, said means for generating zones of differentiated flow comprise at least a plurality of rows of plates arranged perpendicular to the gas flow and on the base of the enclosure. It is quite clear that the distance between the plates in the direction perpendicular to the gas flow is predetermined so as to generate zones with turbulent flow (and zones where the turbulent flow dissipates (essentially behind the plates, in their lower part) Those skilled in the art are fully aware of means for sizing the means for generating zones of differentiated flow, such as for example software for numerical simulation of fluid dynamics (or CFD software). a height and will be arranged in relation to the openings provided in the enclosure so that part of the gas flow flows without disturbance (for example "above" the plates), in order to limit the pressure drop , in particular from one chamber to another. Furthermore, the height and width of the plates may advantageously increase along the gas flow, always so as to limit the pressure drop, no from one enclosure to another, and to control the ratio between calm zones and turbulent zones.

According to one implementation of the invention, said means for generating zones of differentiated flow comprise a plurality of rows and/or columns of plates (or even fins) arranged perpendicular to the gas flow. Advantageously, the plates are organized in several columns (for example 4 columns) and several rows (for example 5 rows). It is quite clear that the distance between the plates in the direction perpendicular to the gas flow is predetermined so as to generate zones with turbulent flow (essentially between the plates) and zones where the turbulent flow dissipates (essentially behind each plate) . A person skilled in the art is fully aware of means for sizing the means for generating zones of differentiated flow, such as for example software for digital simulation of fluid dynamics (or CFD software). Dimensions, in particular concerning the means for generating zones of differentiated flow, are given in the application example described below. In general, the plates will have a height and will be arranged in relation to the openings arranged in the enclosure so that part of the gas flow flows without disturbance (for example "above" the plates), this in order to limit the pressure drop, in particular to one enclosure to another. Furthermore, the height and the width of the plates may advantageously increase along the gas flow, always so as to limit the pressure drop, in particular from one enclosure to another, and to control the ratio between calm zones and turbulent zones.

According to one implementation of the invention, the material of the plates can be felt, ceramic, metal, or a polymer. Such materials indeed have a textured surface, which makes it possible to improve the intimate contact of the gas with the wall. According to another implementation of the invention, the material of the plates can be glass or a plastic material. Such materials are advantageous because they make it possible to avoid corrosion, have an electrostatic potential (which is advantageous for capturing dust), are inexpensive, and can be recycled. As will be described below, the plates can also comprise a coating having adsorption, absorption, photocatalysis and/or photo-oxidation properties, in particular for the second and third chambers.

Alternatively, said means for generating zones of differentiated flow as described above can comprise a plurality of rows of plates arranged perpendicular to the gas flow, each plate comprising a plurality of openings. Advantageously, the plates can be organized in several rows (for example 5 rows), the openings of the plates were positioned substantially at the same location from one plate to another, so as to generate zones with turbulent flow (essentially from an opening from one plate to another plate in the gas flow path) and areas where turbulent flow dissipates (between plate openings). It is quite clear that the distance between the plates in the direction parallel to the gas flow is chosen to generate zones where the turbulent flow dissipates. A person skilled in the art is fully aware of means for sizing the means for generating zones of differentiated flow, such as for example software for digital simulation of fluid dynamics (or CFD software).

The device according to the invention comprises an arrangement of at least three enclosures, each enclosure comprising means for generating zones of differentiated flow, the three enclosures being defined as follows:

- A first enclosure further comprising means for controlling the humidity of the gas stream;

- A second enclosure further comprising means for photo-oxidation and/or photocatalysis of the gaseous compounds that pollute the gas stream; - A third chamber further comprising means for adsorption and / or absorption of polluting gaseous compounds of the gas flow.

It is quite clear that the device according to the invention can comprise other enclosures, called complementary, in its arrangement of juxtaposed enclosures. It should be noted that the use of the terms “first enclosure”, “second enclosure”, “third enclosure”, does not prejudge the order of the enclosures in the arrangement of enclosures of the device according to the invention. Indeed, the enclosures of the device according to the invention can be juxtaposed together in any order. However, in a first preferred embodiment of the invention, the humidity control enclosure as described below can advantageously be arranged first (the order being defined with respect to the direction of the gas flow ) in the arrangement of juxtaposed enclosures, with the advantages which will be described below. Advantageously, in a second preferred embodiment of the invention, if the third enclosure comprises adsorption means, it can be arranged downstream (the direction being defined with respect to the direction of the gas flow) of a setting implementation of the second enclosure comprising oxidation means. Indeed, the oxidized VOCs will then be more effectively adsorbed.

According to the invention, the arrangement of juxtaposed enclosures of the device according to the invention comprises a first enclosure intended for regulating the humidity of the gas flow, comprising means for controlling the humidity of the gas flow.

According to one implementation of the invention, the regulation of the humidity of the gas stream consists in lowering the humidity level of the gas stream, or even in drying the gas stream, as described in the embodiments below. after.

According to an implementation of the invention, the regulation of the humidity of the gas flow can be carried out by cooling, in particular by cooling the means for generating zones of differentiated flow. According to one embodiment of this implementation, these means for controlling the humidity of the gas flow comprise means for circulation of a heat transfer fluid in the enclosure, arranged to allow the cooling of the means for generating zones of differentiated flow. These means for cooling the gas flow may comprise an inlet and an outlet for a heat transfer fluid arranged on at least one of the faces of the first enclosure, and a circuit for causing the heat transfer fluid to circulate so that it is in contact with the means for generating zones of differentiated flow. The heat transfer fluid can be deionized water, solutions of glycol and water or dielectric fluids, or biodegradable solutions from renewable resources (for example biosourced 1,3-propanediol from the fermentation of glucose syrup). The cooling of the gaseous flow makes it possible to condense the water vapor present in the gaseous flow, which contributes to a more efficient filtration of the device according to the invention. Indeed, in particular in the first preferred implementation of the invention according to which the enclosure for regulating the humidity of the gas flow is arranged upstream of the other enclosures, the gas flow is dried before entering the following enclosures ( the order of the enclosures being considered with respect to the direction of the gas flow) of the arrangement of enclosures according to the invention, which prevents the water vapor from "occupying" the sites of photooxidation and/or photo -catalysis and/or the adsorption and/or absorption sites of the enclosures arranged downstream. In addition, the condensed water, in particular on the means for generating a differentiated hydrodynamic flow, contributes to effectively trapping the particles of the gas flow, in particular the largest ones, and prevents fouling of the enclosures downstream.

Advantageously, this embodiment further comprises means for collecting and eliminating this condensed water laden with particles. These means for collecting and removing the condensed water laden with particles can comprise an outlet provided in the lower part of the enclosure. In this way, the water laden with particles will flow by gravity along the means for generating a differentiated hydrodynamic flow to be evacuated through the outlet provided in the lower part of the first enclosure. Alternatively, the means for collecting and eliminating the condensed water laden with particles can comprise a settling tank, provided with a level control, to trigger a drain depending on the level. In a complementary way, the means of collection and elimination can comprise a mechanical scraper, or a rinsing nozzle placed in the lower part of the enclosure.

According to another implementation of the invention, the means for regulating the humidity of the gas flow can comprise a desiccant (such as for example a calcium chloride, phosphoric acid), an adsorber (such as for example alumina, activated clays, silica gel), a permeation membrane or even liquids such as, for example, glycol or propylene carbonate.

Advantageously, the means for regulating the humidity of the gas flow can be dimensioned to determine a humidity level of the gas flow at the outlet of the first enclosure, depending on the polluting species to be reduced, which can be between and 4% and 0.5 %, in particular when it is arranged upstream of the second type of enclosure. Indeed, a humidity level at the inlet of the second enclosure included in these ranges allows, under UV radiation and/or ozone treatment in the second enclosure, the formation of free radicals useful for the oxidation of VOCs and/or or NOx. According to the invention, the arrangement of juxtaposed enclosures of the device according to the invention comprises a second enclosure intended to eliminate polluting gaseous compounds by photo-oxidation and/or photo-catalysis. These reactions cause the mineralization of these polluting gaseous compounds. This second chamber comprises means for photooxidation and/or photocatalysis of gaseous compounds that pollute the gas stream. According to one implementation of the invention, the means for photo-oxidation and/or photo-catalysis of the gaseous compounds that pollute the gas stream can comprise at least: a light source (for example a UV lamp, preferably a neon lamp UV) to irradiate (for example by means of at least one optical fiber deployed in the enclosure) bodies coated with a photo-active phase, preferably a coating of titanium oxide (TiOs) in the case of the photo-oxidation and a coating of mixed oxides (for example a titanium oxide TiOx with 2<x<0 associated with an inorganic oxide such as ceria, a cobalt oxide, vanadium, or noble metals) in the case of the photo -catalysis. Advantageously, the bodies coated with a photo-active phase of this implementation can correspond to at least part of the means for generating a differentiated hydrodynamic flow in the enclosure. In other words, for example, at least part of the plates intended to generate differentiated hydrodynamic zones can be coated with a photo-active phase, capable of photo-oxidation and/or photo-catalysis. Preferably, all the plates intended to generate differentiated hydrodynamic zones can be coated with a photo-active phase. According to an exemplary embodiment, some of the plates intended to generate differentiated hydrodynamic zones can contribute to photo-oxidation of gaseous pollutants and other plates can contribute to photo-catalysis of these or other gaseous pollutants. Thus, in general, this second enclosure makes it possible to treat the VOCs and NOx contained in the gaseous flow at ambient temperature and pressure, via the use of an adequate coating of surfaces in contact with the turbulent effluent and of the make-up of reagent and/or radiant energy. This oxidation capacity is particularly advantageous for the gas phase oxidation of NOx (more particularly NO) in order to obtain a mixture richer in NO2, N2O3, etc., which makes it possible, for example, to improve the solubility of NOx in the aqueous phase, and promote the adsorption of NO2 rather than NO. Moreover, in the second preferred mode of the invention, the oxides thus formed, which are then entrained by the gas flow towards at least the third chamber, are more reactive to the adsorption mechanism.

It is quite clear that the device according to the invention can comprise several enclosures of the type of the second enclosure, each comprising distinct photo-active phases, so as to capture the most different gaseous pollutants. Advantageously, for the largest molecules, the device according to the invention comprises an enclosure intended to eliminate polluting gaseous compounds by photo-oxidation placed upstream of an enclosure intended to eliminate polluting gaseous compounds by catalysis. This arrangement is particularly advantageous for allowing the mineralization of formaldehyde into CO2.

According to the invention, the arrangement of enclosures of the device according to the invention comprises a third enclosure intended to trap polluting gaseous compounds by adsorption and/or absorption.

According to an implementation of the invention according to which the third chamber comprises means for adsorbing the gaseous compounds that pollute the gas flow, these adsorption means can comprise bodies coated with an adsorbent agent (such as ceramic monoliths or metal, etc ...) or fixed beds of granules (such as a molecular sieve, for example formed of zeolites or activated carbon). The purpose of this third enclosure is to capture pollutants via physi-sorption depending on the materials used. Advantageously, the bodies coated with an adsorbent agent according to one implementation may correspond to at least part of the means for generating a differentiated hydrodynamic flow in the enclosure. For example, at least part of the plates intended to generate a differentiated hydrodynamic flow can be coated with at least one adsorbent agent, preferably all the plates. Advantageously, the method according to the invention comprises a step of regenerating the adsorbents, for example carried out ex situ. According to an alternative, the fixed beds of granules can be formed by means of gabions which are arranged in contact with the means for generating a differentiated hydrodynamic flow in the enclosure (for example plates).

According to an implementation of the invention according to which the third chamber comprises means for absorbing the gaseous compounds that pollute the gas stream, these absorption means may comprise bodies coated with an absorbent agent (such as an activated alumina or not and/or zeolite, comprising copper and/or silver species and groups, for example, supported and/or exchanged) or even fixed beds of granules (such as MOFS, potassium oxides or carbonates), the granules being the active phase. The purpose of this third chamber is to capture pollutants via chemi-sorption depending on the materials used. Advantageously, the bodies coated with an absorbent agent according to one implementation may correspond to at least part of the means for generating a differentiated hydrodynamic flow in the enclosure. For example, at least part of the plates intended to generate a differentiated hydrodynamic flow can be coated with at least one absorbent agent, preferably all the plates. Advantageously, the process according to the invention can comprise a step of regenerating the adsorbents, for example carried out ex situ or in situ, with the dispersion of a rinsing solvent or of water vapour. According to an alternative, which can however be combined with the embodiment described above, the beds fixed granules are formed by means of gabions which are arranged in contact with the means for generating a differentiated hydrodynamic flow in the enclosure (for example plates). An absorbing solvent (such as a chlorinated, basic or oxidizing aqueous solvent) can be injected or sprayed using nozzles present in the module to act as a capture agent. The flow of the solvent can also participate in the entrainment of the collected dust.

It is quite clear that the device according to the invention can comprise several enclosures of the type of the third enclosure, each comprising different adsorbents and/or absorbents, so as to capture the most different gaseous pollutants.

In general, the device according to the invention is particularly advantageous because of its modularity, the various enclosures being able to be arranged, dimensioned, and functionalized according to the particles and the polluting gaseous compounds to be eliminated from the gas flow, but also according to the times residence of these solid, liquid or gaseous pollutants. Indeed, the high gas velocity allows the creation of turbulence in the enclosures and determines a distinct residence time for particles such as gaseous pollutants. According to one implementation of the invention, in line with these characteristic residence times, the residence time of the species can be increased or reduced by acting on the volumes of the enclosures, the spacings, the generating elements of a differentiated hydrodynamic flow (for example the plates) within the enclosures, or via the addition in series or in parallel of additional elements, or even by modifying their orientation/inclination.

Advantageously, the device according to the invention comprises means for controlling, preferably remotely and without human intervention, the arrangement of the means for generating differentiated hydrodynamic flow zones of at least one of the enclosures.

According to an implementation of the invention according to which the means for generating zones of differentiated hydrodynamic flow are in the form of a plurality of rows and a plurality of columns of plates, it is possible for example to control the spacing (lateral or transverse) between these plates, their inclination with respect to an axis perpendicular to the plane of the gas flow, and/or their orientation with respect to an axis situated in the plane of the gas flow. Thus, the plates, which are in the most general case oriented perpendicular to the gas flow, can be oriented and/or inclined to modulate the residence times in the enclosure considered. Similarly, the spacing between the plates of the same row can be modulated in order to create more or less significant turbulence, and the spacing between the plates of the same column can also be modulated to maximize the contact of the gas flow. with the plates. Advantageously, these means can also make it possible to modify the dimensions of the plates in situ by deploying elements that can be added to the plates, or even to add additional plates.

According to an implementation of the invention according to which the means for generating zones of differentiated hydrodynamic flow can be in the form of a plurality of rows of plates comprising openings in the form of diaphragms, the opening can be controlled of these diaphragms so as to create more or less significant turbulence, for example by means of mechanical actuators (motors) adapted from blades and/or from the support constituting the diaphragm via rotation of the latter, or by elements expanding under the effect of heat and/or humidity (such as a thermostat).

According to one implementation of the invention, the means for controlling remotely and without human intervention the arrangement of the means for generating differentiated hydrodynamic flow zones of at least one of the enclosures can comprise computer means controlling an automaton connected to means for adjusting the arrangement of the means for generating zones of differentiated hydrodynamic flow such as shafts, rails, pivots, pistons, etc.;

Advantageously, the device can be controlled by an electronic/computer control system allowing manual, automatic or semi-automatic remote control. Thus, the control system can comprise electronic/computer means connected on the one hand to means for measuring the quality of the air at the outlet of the device according to the invention and to means for controlling the device, in particular means for controlling the arrangement of the means for generating a differentiated hydrodynamic flow, and connected on the other hand to a man/machine interface. Thus, depending on the quality of the air measured at the outlet of the device, it is possible for example to control the arrangement of the means for generating a differentiated hydrodynamic flow. Monitoring of the process can therefore be done remotely, minimizing maintenance operations requiring human intervention in situ. Connections can be provided by all known means (local internet network, etc.) and use the same connection system as that used, for example, for the monitoring and maintenance of ventilation/extraction means provided for in confined environments or semi-confined. Advantageously, the control system can comprise a sensor for measuring concentrations of gaseous pollutants and/or particles, downstream and/or upstream of the device according to the invention. Advantageously, the sensor for measuring the concentrations of gaseous pollutants and/or particles can comprise means for remote analysis of the measurements carried out in situ of gaseous pollutants and/or particles, the measurements being transmitted for example by electric wire, by optical fiber or by a wireless communication system to these means remote analysis. Advantageously, the control system can further comprise a humidity sensor (in particular upstream and/or downstream of the first enclosure), temperature, gas flow rate (to control the pressure drop in particular) to improve manual, automatic or semi-automatic remote control of the device and of the method according to the invention.

The control system can also comprise means for alerting when the treatment of the air is insufficient by the device and the method according to the invention, or when one of the elements allowing the operation of the device proves to be defective (air flow air, humidity regulation, condensation management, etc.) According to this implementation of the invention, this alert can be triggered when the concentration of at least one particulate or molecular pollutant is greater than a predefined threshold. According to one implementation, the alert can be given in the form of a visual or sound indication. According to one implementation, the alert means can be positioned in the immediate vicinity of the device or allow remote alerting, for example via an electronic message sent to a smartphone and/or to a computer.

According to one implementation of the invention, the device according to the invention may further comprise means for attenuating the noise emitted by the device when it is in service, such as for example by means of silencers used for vehicles, or padding around the various speakers.

FIG. 1 schematically presents a non-limiting embodiment of the device according to the invention. For this embodiment, the device is formed by three juxtaposed enclosures 10, 20, 30, crossed right through by a gaseous flow F1 (incoming flow), F2 (outgoing flow) of the device thanks to openings provided 11 in the faces of the parallelepipedic enclosures perpendicular to the gas flow (only the openings of the face upstream (relative to the direction of the gas flow) of the first enclosure 10 are shown). Each enclosure 10, 20, 30 comprises an inlet 12 intended for the supply of reagents and/or energy necessary for the proper functioning of the enclosure. In this figure, only the inlet 12 intended for supplying a heat transfer fluid into the enclosure 10 is shown. The device further comprises an opening 41 of a collection zone (not shown) of the particulate pollutants of the enclosure 10. FIG. 2 schematically presents a non-limiting embodiment of the first enclosure 10 of the device according to the invention. For this embodiment, the enclosure 10 is parallelepipedic in shape, and comprises six rows of three columns of plates 50 arranged perpendicular to the gas flow F1 entering the enclosure 10 through the openings 11 arranged on the upstream face of the enclosure 10 (neither the outgoing gas flow nor the openings arranged on the downstream face of the enclosure 10 are shown here). The plates 50 are arranged in the lower part of the enclosure 10 to generate a turbulent flow. The upper part of the enclosure 10 has no plates 50. The enclosure 10 also comprises an opening 13 for the supply of a heat transfer fluid intended to circulate in a circuit 13' in contact with the plates 50, so as to controlling the temperature of the plates 50, means 14, 15, for adjusting the arrangement of the plates 50, in the form of an actuator 14, shafts 15 for adjusting the inclination of the plates, and rails (not shown). It is quite clear that such adjustment means can be equally deployed to the other enclosures of the device according to the invention. This enclosure 10 further comprises a zone 40 for collecting essentially particulate pollutants, which here flow by gravity towards an outlet 41 .

FIG. 3 schematically presents another non-limiting embodiment of the first enclosure 10 of the device according to the invention. For this embodiment, the enclosure 10 is also of parallelepipedal shape, and comprises 3 rows of plates 60 provided with openings in the form of diaphragms 61 (only two diaphragms on the most downstream plate 60 are shown), arranged perpendicular to the gas flow F1 entering the enclosure 10 (neither the openings provided on the upstream face of the enclosure 10, nor the openings provided on the downstream face of the enclosure 10, nor the gas flow leaving the enclosure 10 are shown here). The opening of the diaphragms 61 is controlled to generate the turbulent flow. This enclosure 10 further comprises a zone 40 for collecting essentially particulate pollutants, which here flow by gravity towards an outlet 41 . Although not shown, it is clear that this enclosure can also include means for circulating a heat transfer fluid, and means for controlling the opening diameters of the diaphragms 61.

FIG. 4 schematically presents a non-limiting embodiment of the second enclosure 20 of the device according to the invention. For this embodiment, the enclosure 20 is of parallelepipedal shape, and comprises six rows of three columns of plates 50 arranged perpendicular to the gas flow F1 entering the enclosure 20 through the openings 21 provided on the upstream face of the enclosure 20 (neither the outgoing gas flow nor the openings arranged on the downstream face of the enclosure 20 are not represented here). The plates 50 are arranged in the lower part of the enclosure 20 to generate a turbulent flow. The upper part of the enclosure 20 has no plates 50. The enclosure 20 also comprises an opening 23 for the entry of UV radiation (coming from a UV lamp, not shown and external to the device), a network of optical fibers 24 to irradiate the surface of the plates 50 provided with a photo-active coating (represented schematically by dashes).

FIG. 5 schematically presents a non-limiting embodiment of the third enclosure 30 of the device according to the invention. For this embodiment, the enclosure 30 is parallelepipedic in shape, and comprises six rows of three columns of plates 50 arranged perpendicular to the gas flow F1 entering the enclosure 30 through the openings 31 arranged on the upstream face of the enclosure 20 (neither the outgoing gas flow nor the openings arranged on the downstream face of the enclosure 30 are shown here). The plates 50 are arranged in the lower part of the enclosure 30 to generate a turbulent flow. The upper part of the enclosure 30 has no plates 50. For this embodiment, the surface of the plates 50 is provided with an adsorbent (represented schematically by a texture applied to the plates 50).

The invention also relates, in a second aspect, to a method for eliminating particles and polluting gaseous compounds from a gaseous flow originating from the air present in a confined or semi-confined medium.

Advantageously, the method according to the invention is implemented by means of the device according to any one of the embodiments described above. More specifically, the method according to the invention may comprise the following steps: a) at least part of the air present in a confined or semi-confined medium is led, in the form of a gaseous flow, into the device according to any of the embodiments described above; b) polluting particles and gaseous compounds contained in the gas stream are eliminated by means of the device according to any one of the embodiments described above;

The first step of the method according to the invention can be implemented by placing the device according to any one of the embodiments described above upstream and/or downstream of means of ventilation and/or extraction of the confined or semi-confined environment of interest when such means exist.

In accordance with one embodiment of the invention, the polluting particles and gaseous compounds can be eliminated by means of the following steps:

- a step of controlling the humidity of the gas stream;

- a step for implementing photo-oxidation and/or photo-catalysis of the gaseous compounds that pollute the gas stream;

- a stage of adsorption and/or absorption of polluting gaseous compounds from the gas stream.

These steps can be implemented in this order, or another order.

Example

The characteristics and advantages of the method according to the invention will appear more clearly on reading the application example below.

For this example of application, we consider a device formed by three chambers, of parallelepipedal shapes, comprising elements for generating a hydrodynamic disturbance of the gas flow formed by a plurality of plates organized in columns and rows, the face upstream of these plates featuring a felt-like material.

Figure 6 illustrates one of the enclosures in this arrangement. The characteristics of this chamber have been dimensioned to allow a reduction of between 50 and 80% of the particles by mass, the particles having a size at least greater than 0.5 pm, preferably greater than 0.1 pm, for a gas flow having a flow rate of between between 500 m ³ /h and 10,000 m ³ /h, preferably between 500 m ³ /h and 5,000 m ³ /h. The references are identical to those of the preceding figures.

The ranges of the main characteristics of this enclosure, sized to achieve the filtration objectives above, are given below:

H: Enclosure height in the range [0.05m- 1m], preferably [0.05m- 0.6m];

- h: flow override height, defined by h= (1 -y). H with including in the range [0.3-1];

I: enclosure width, within the range [0.05m-1m], preferably [0.05m-0.6m]; - L: Enclosure length within the range [0.5m-8m], preferably [0.5m- 5m];

- e: thickness of a plate 50, included in the range [0.003m-0.1 m]

- u: width of a plate 50, which cannot exceed E

- N: number of rows of plates 50 included in the range [1-10], preferably [1 - 5]

- sp: spacing in the direction parallel to the flow between the plates 50, included in the range [0.003m-0.05m];

- h’: height of a plate 50, at least equal to h;

R: ratio between the surface of the openings 11 of diameter d arranged on the downstream and/or upstream face of the enclosure, and the surface S of the solid parts of this same face comprised between [0.15-0.5];

- Surface of the plates compared to the total volume of the containment: [500m ^-1 -1000m ^-1 ];

- Density of plates relative to the volume of the enclosure within the range [100-50,000] plates/m ³ .

In conclusion, the device and the method according to the invention are inexpensive in terms of energy, installation and maintenance, and the device according to the invention is compact. They make it possible to treat both pollution in particulate form and in gaseous form in a single operation. The device according to the invention is particularly advantageous because of its modularity, the various enclosures being able to be arranged, dimensioned, and functionalized according to the particles and the polluting gaseous compounds to be eliminated from the gaseous flow.

Claims

Claims 1. Device for removing polluting particles and gaseous compounds from a gas flow (F1, F2) coming from the air present in a confined or semi-confined environment, said device comprising an arrangement formed by a plurality of enclosures ( 10, 20, 30) arranged in series, said enclosures (10, 20, 30) comprising openings (11, 21, 31) arranged to allow said gas flow (F1, F2) to pass on either side of said plurality of enclosures (10, 20, 30) arranged in series, each enclosure (10, 20, 30) comprising at least means (50, 60, 61) for generating turbulent flow zones and turbulent flow zones non-turbulent flow of said gas flow in said enclosure, characterized in that said arrangement comprises at least: - a first enclosure (10) comprising means for controlling the humidity of said gas stream (13, 13'); - a second enclosure (20) comprising means (23, 24) for photo-oxidation and/or photo-catalysis of said polluting gaseous compounds of said gas stream; - a third enclosure (30) comprising means for adsorption and/or absorption of said polluting gaseous compounds from said gas stream. 2. Device according to claim 1, wherein said means for generating turbulent flow zones and non-turbulent flow zones of said gas flow from at least one of said enclosures (10, 20, 30) comprise a plurality of rows and/or a plurality of columns of plates (50) arranged perpendicular to said gas flow and on the base of said at least one enclosure. 3. Device according to claim 1, wherein said means for generating turbulent flow zones and non-turbulent flow zones of said gas flow from at least one of said enclosures (10, 20, 30) comprise a plurality of rows plates (60) arranged perpendicular to said gas flow and on the base of said at least one enclosure, each of said plates comprising a plurality of openings in the form of diaphragms (61). 4. Device according to one of the preceding claims, wherein said device comprises means (14, 15) for controlling the arrangement of said means (50, 60, 61) for generating turbulent flow zones and turbulent flow zones. non-turbulent flow of said gas flow from at least one of said enclosures (10, 20, 30), in particular the position and/or the inclination and/or the orientation of the said means for generating turbulent flow zones and zones of non-turbulent flow of said gas stream. 5. Device according to one of the preceding claims, wherein said means for controlling the humidity (13, 13 ') of said gas flow from said first enclosure (10) comprises means for circulating a heat transfer fluid (13, 13 ' ) in said first enclosure (10). 6. Device according to one of the preceding claims, wherein said means (23, 24) for photo-oxidation and/or photo-catalysis of said second chamber comprise at least one light source, preferably a UV lamp, and bodies coated with a photo-active phase. 7. Device according to one of the preceding claims, wherein said adsorption means of said third enclosure comprise bodies coated with an adsorbent material or a fixed bed of granules. 8. Device according to one of the preceding claims, wherein said absorption means of said third enclosure comprise bodies coated with an absorbent material, a fixed bed of granules or means for dispersing an absorbent solvent. 9. Device according to one of the preceding claims, wherein said arrangement is formed by said first enclosure (10), said second enclosure (20) and said third enclosure (30) arranged in series and in this order along said gas flow (F1.F2). 10. Process for eliminating polluting particles and gaseous compounds present in the air of a confined or semi-confined medium, characterized in that said process comprises at least the following steps: a) one conducts, in the form of a gas stream, at least part of the air of said confined or semi-confined medium in at least one device for removing at least particles from a gas stream originating from the air present in a confined or semi-confined medium according to any of the preceding claims; b) said particles and said polluting gaseous compounds are eliminated from said gas stream by means of said at least one device.