Ozone decontamination cabinet, particularly for the degradation of PAHs and / or the destruction of microorganisms

Abstract

The cabinet (10) comprises a closed enclosure (30) receiving the effects to be decontaminated, fresh air intake means (78, 80) and an air treatment unit with a motor-driven fan (50), an ozone generator and a heating element to create a flow of heated and ozonated pulsed air (APL) at a content of between 0.5 and 3 ppm. An extraction and filtering unit (62, 64, 66) extracts and filters a fraction (AEX) of the contaminated air (ACT). A bottom or floor wall (18) of the cabinet comprises diffusion vents (40) for the pulsed air (APL) supplied by a collector (76) connected to the air treatment unit. The flow of pulsed air (APL) is diffused by the diffusion vents (40) essentially in the lower part (32) of the enclosure. (Figure to be published with the abstract: Figure 8)

Description

Title of the invention: Ozone decontamination cabinet, in particular for the degradation of PAHs and / or the destruction of microorganisms

[0001] The invention relates to a decontamination cabinet, in particular for the degradation of polycyclic aromatic hydrocarbons (PAHs) and / or the destruction of microorganisms present on contaminated effects.

[0002] An example of a contaminated item is that of firefighters' outfits, boots, gloves, etc. and other personal protective equipment (PPE) after a firefighting intervention: these items are then contaminated by reaction products of pyrolytic origin from the incomplete combustion of organic materials, and mainly made up of toxic PAHs, which are very chemically stable and difficult to degrade.

[0003] Ozone is recognized in this respect as a reagent with high oxidative power for breaking the cycles and double bonds of PAHs to allow their oxidation and degradation into non-toxic final reaction products. More precisely, the majority reaction mechanism of ozone with PAHs is a so-called Langmuir-Hinshelwood mechanism, with a first phase of rapid adsorption, without reaction, of ozone on the surface of the contaminating particles, followed by a slower surface reaction, during which the ozone implanted on the surface of the particles will react with the reaction sites on the surface, this latter reaction being favored and accelerated by forced circulation of the flow of air loaded with ozone. The level of ozone in the air necessary to achieve the destruction of PAHs can reach 2.5 to 3 ppm.

[0004] WO 2019 / 113434 Al (Oshkosh Corp.) describes a firefighting intervention vehicle comprising a decontamination chamber in which the contaminated effects of the firefighters can be enclosed after the intervention. For decontamination, this chamber is swept by a flow of outside air, with ozone and humidity being injected at one end of the chamber and, at the opposite end, the contaminated air being sucked through a filter before being evacuated to the outside.

[0005] The chemical behavior of ozone described above (Langmuir-Hinshelwood mechanism) also allows, independently or in addition, the destruction of microorganisms (bacteria, viruses, molds, etc.), by lysis of unsaturated fatty acids, glycoproteins, glycolipids, amino acids, certain enzymes and finally DNA due to the very high oxidative power of ozone, typically six times greater than that of chlorine. Unlike chemical decontamination by a flow of ozonated air, this type of biological decontamination is usually usually operated in the liquid phase by ozone-treated water, although treatment by air flow is also possible. Here again, high ozone levels should be provided, typically in the order of 1.5 to 2.5 ppm.

[0006] Ozone is also often proposed in domestic applications for "purification" or "sanitation" of the air (elimination of bad odors, etc.), but then with much lower ozone levels, typically of the order of 0.2 ppm, so as not to cause risks to the environment or to the health of users, often non-professionals. WO 2018 / 167528 Al (Bluezone IP Holding LLC) describes such a type of device, implementing a closed circuit for recirculating and filtering a flow of mixed air loaded with ozone in a closed volume where this air is put into continuous circulation.

[0007] In the case of the present invention, it is a question of using much higher ozone contents (typically five to ten times higher than those of air "purification" applications), therefore potentially dangerous if the ozonated air were released into the environment without special precautions at such concentrations.

[0008] Another factor to consider is the fact that the phenomena described above allowing such chemical and / or biological decontamination by a flow of air with a high ozone content can be clearly favored and accelerated by an increase in the temperature of the air loaded with ozone.

[0009] It is indeed noted that ozone levels from 0.8 ppm combined with temperatures up to 50°C, or even 60 or 65°C if the effects to be decontaminated support it, it is possible, even for effects heavily loaded with various contaminants and pollutants, to achieve very effective decontamination in a relatively acceptable time (typically 2 to 6 hours).

[0010] Heating the air has the additional advantage of accelerating the drying of the effects to be decontaminated, which are often not only polluted but also wet, as in the case of the equipment of firefighters called to extinguish a fire.

[0011] One of the aims of the invention is to propose an ozone decontamination cabinet including optimized means for mixing a flow of ozonated air heated and continuously recirculated in the closed cabinet containing the effects to be treated. In particular, it is a question of adapting the geometry and the configuration of the different elements of the cabinet and its equipment to allow not only an effective and rapid decontamination, but also an optimization of the overall thermal balance of the assembly (which must be able to operate for several hours in a row with reasonable energy consumption), all without releasing into the environment pollutants or air excessively loaded with ozone.

[0012] To this end, the invention proposes a cabinet comprising, in itself known: a closed enclosure intended to receive effects to be decontaminated, defined by vertical walls including a door, and by a floor wall and a ceiling wall of the cabinet; fresh air intake means, communicating with the exterior of the cabinet and with the interior volume of the enclosure; an air treatment unit, comprising a motor-driven fan in upstream and downstream communication with the interior volume of the enclosure and with at least one ozone generator and at least one heating element, so as to create inside the enclosure a flow of pulsed air coming into contact with the contaminated effects, the pulsed air being heated and ozonated to an ozone content of between 0.5 and 3 ppm; and an extraction and filtering unit, capable of extracting a fraction of the contaminated air from the enclosure, and of filtering this fraction of contaminated air loaded with ozone and particles before discharge outside the cabinet.

[0013] Characteristically of the invention, the closed enclosure being an enclosure extending in height by defining an upper part and a lower part, at least one of the vertical walls of the cabinet and / or the floor wall of the cabinet comprises diffusion vents diffusing the pulsed air and situated essentially in the lower part of the enclosure. In addition, the cabinet comprises at least one pulsed air collector extending along the upper part of the enclosure and connecting the air treatment unit to the diffusion vents, so as to receive the flow of pulsed air produced by the air treatment unit to diffuse it essentially in the lower part of the enclosure by the diffusion vents.

[0014] According to various advantageous subsidiary characteristics: - the lower part of the enclosure receiving the flow of pulsed air produced by the air treatment unit extends over 30% to 70%, preferably 40% to 60%, of the total height of the interior volume of the enclosure; - the fresh air intake means comprise intake vents located on a vertical wall of the cabinet in the lower part of the enclosure, and / or in the floor wall of the cabinet; - the cabinet further comprises in the ceiling wall and / or near the ceiling wall suction vents located upstream of the motor fan, for the recirculation of contaminated air, in particular hot air not saturated with humidity; - at least one of the suction inlets is fitted with a disinfectant and / or deodorizing cassette; at least one of the vertical walls of the cabinet forms a wall of the pulsed air collector; and / or - the extraction and filtering unit comprises: an extraction fan motor; an active filter; and an exhaust chimney in the upper part of the cabinet. The extraction fan motor is in communication with the interior volume of the enclosure and with the active filter to bring it to the active filter, before discharge outside the cabinet. through the chimney, the said fraction of contaminated air loaded with ozone.

[0015] In an advantageous embodiment, the pulsed air collector comprises a triple wall defining two ducts extending parallel over at least part of the collector, with on the inside of the enclosure, an internal duct forming a conduit connecting the air treatment unit to the diffusion vents and conveying the pulsed air flow downwards, and on the outside of the cabinet, an external duct forming a static thermal insulation layer.

[0016] In the latter case, the external sheath may, as a variant, form a conduit connecting fresh air intake vents to the air treatment unit and conveying a flow of fresh air upwards, the two adjoining sheaths then forming a heat exchanger between the flow of heated pulsed air leaving the air treatment unit and the flow of fresh air entering the air treatment unit.

[0017] A non-limiting example of implementation of the invention will now be described with reference to the appended drawings, where the same references designate identical or functionally similar elements from one figure to another.

[0018] [fig. 1] represents, in perspective, a decontamination cabinet according to a first embodiment of the invention.

[0019] [fig.2] is a front elevation view of the enclosure of Figure 1.

[0020] [fig.3] is a perspective view of the air handling unit of the cabinet of Figures 1 and 2, with the top cover removed to show its various component parts.

[0021] [fig.4] is a cross-sectional view of the air handling unit of Figure 3.

[0022] [fig.5] shows the air handling unit of Figures 3 and 4, seen from below in perspective.

[0023] [fig.6] is a graph showing the evolution of the ozone rate inside the enclosure of the cabinet over time.

[0024] [fig.7] is a cross-sectional view of the cabinet of Figures 1 and 2, illustrating the how the different air flows circulate during the decontamination treatment.

[0025] [fig.8] is homologous to [fig.7] for a second embodiment of the cabinet of the invention, implementing a double-bottomed wall forming a heat exchanger.

[0026] [fig.9] is an enlarged view of the upper rear portion of the illustrated cabinet Figure 8.

[0027] We will first describe the arrangement of a decontamination cabinet according to a first embodiment of the invention, with reference to Figures 1 to 5.

[0028] The decontamination cabinet 10 is in the form of a tall piece of furniture, with an interior volume defined by two vertical side walls 12, a vertical bottom wall 14, a door 16, a floor wall 18 and a ceiling wall 20. Various accessories such as supports 22 forming a rack for gloves or boots, a 24 grid for placing small objects, a rod under the ceiling wall, etc., allow the items to be decontaminated to be placed in the cabinet, leaving enough space around them so that the interior air can circulate around them.

[0029] The cabinet is surmounted by a technical block 26 integrating elements which will be described more precisely with reference to Figures 3 to 5, as well as front controls for adjusting the operating parameters (temperature, operating time, etc.) and monitoring the process (ozone level, internal temperature, various safety features). This technical block is preferably arranged at the top rather than at the bottom of the cabinet, which protects it in particular from various splashes, in particular when cleaning the cabinet with a lot of water.

[0030] The walls 12 to 20 of the cabinet define an interior volume forming a closed enclosure 30, which can be accessed by opening the door 16. The latter may include, in a manner known per se, locking safety devices preventing it from being opened until the internal temperature and the ozone level in the enclosure have fallen below a safety threshold.

[0031] The enclosure 30, which has an essentially vertical shape (its height is greater than its depth) comprises a lower part 32 and an upper part 34, the lower part corresponding to 30-70% of the total height of the enclosure, preferably 40-60%, for example 50% as in the example illustrated in the figures.

[0032] For the circulation of the different air flows, the enclosure comprises: - fresh air intake vents (air flow referred to as ANF hereinafter), which are inlet orifices such as the vents 36 on the front of the technical unit 26 and / or the vents 38 provided at the bottom of the door 16 and / or the vents 80 for air intake from below the cabinet (as illustrated in [fig.8]); - vents for distributing pulsed air (air flow referred to as APL hereinafter), which are outlet orifices such as the vents 40 located in the lower part of the bottom wall 14 and / or the vents 68 provided in the floor wall 18 (as illustrated in Figures 7 and 8); - suction vents 44 for recycled air (air flow designated ARC hereinafter), which are inlet orifices for air laden with contaminants such as the vents 44 in the ceiling wall 20 (Figures 4 and 5); and - extraction vents for the contaminated air to be extracted (air flow designated AEX hereinafter), which are inlet orifices for air laden with contaminants such as the vents 66 provided in the ceiling wall 20 (Figures 4 and 5).

[0033] Characteristically of the invention, the diffusion vents 40, which deliver the ozonated and heated air produced by the technical unit 26, are arranged only (or, at the very least, mainly) on the lower part of the enclosure 30.

[0034] The structure of the technical block 26 will now be described in detail, with reference to Figures 3 to 5.

[0035] To bring the pulsed air APL from the technical block 26, located above the enclosure 30, to the diffusion vents 40 located in the lower part 32 of this same enclosure, one or more collectors 42 for distributing the pulsed air APL are provided, extending for example in the back wall over the entire height of the upper part 34 of the enclosure 30.

[0036] The technical block 26 comprises a motor-driven fan 50 with its volute, which draws in the fresh air ANF through the intake inlet 36 to draw it towards a heating element 52 then towards one or more ozone generators 54, so as to deliver under pressure a heated and ozonated pulsed air APL to the inlet 56 of each of the vertical collectors 42, which will guide this pulsed air APL to the diffusion inlets 40 in the lower part 32 of the enclosure 30.

[0037] The motor-driven fan 50 also sucks in, via the suction vents 44, contaminated air coming from the interior volume of the enclosure 30, in order to recycle it to the diffusion vents 40 via the collectors 42.

[0038] The proportion, in the air flow pulsed by the motor-driven fan 50, of the recycled air ARC compared to the fresh air ANF is determined by construction, as a function of the relative sections of the intake vents 36 (on the front of the technical block 26) and 38 (in the door 16) and of the suction vents 44 (in the ceiling wall 20, under the technical block 26).

[0039] Recycling ensures continuous mixing of the heated ozonated air, which accelerates both the reaction mechanisms for destroying PAHs and / or microorganisms and possibly the drying of the effects placed in the cabinet, and therefore reduces the total time required for complete decontamination.

[0040] Another advantage of air recycling is that a large portion of the already heated, unsaturated moisture air can be reused to accelerate the drying of wet effects and thus reduce the overall energy consumption required for the process.

[0041] Furthermore, a removable cassette 58 may optionally be mounted on one or more of the suction vents 44 to diffuse with the recycled air a disinfectant and / or deodorizing product which will come into contact with the effects placed inside the enclosure 30. The product is for example placed on an absorbent support which is placed in the cassette 58 to allow its diffusion in the volume of the enclosure 30. The principle of recirculation makes it possible to maintain the effectiveness of the product inside the cabinet for longer.

[0042] The technical block 26 further comprises an extraction fan 62 connected, at the inlet, to air extraction vents 60 AEX located on the ceiling wall 20 and, at the outlet, to a chimney 64 for evacuation to the outside atmosphere, this chimney in incorporating a filter 66, in particular an activated carbon filter. This filter ensures the retention of contaminated particles after their oxidation by ozone as well as the destruction of excess ozone before release into the atmosphere, so that the final ozone content of the air released outside does not exceed the authorized regulatory thresholds, typically no more than 0.1 ppm.

[0043] The proportion, in the contaminated air flow ACT, of the extracted air AEX sucked in by the extraction fan 62 compared to the recycled air ARC sucked in by the main fan 50 is determined by construction, as a function of the relative sections of the extraction vents 60 and the suction vents 44 provided in the ceiling wall 20 of the enclosure.

[0044] Figure 6 illustrates an example of the variation in the ozone level over time which was recorded inside the enclosure 30 under experimental conditions where the ozone is produced continuously by a single ozone generator 54, and where the extraction fan 62 is supplied either continuously (curve A), or cyclically (curve B) with an alternation of 15-minute cycles without extraction (providing a rapid increase in the ozone level) and 5-minute extraction cycles intended to ensure the evacuation of the reaction products (and generating a correlative drop in the ozone level in the enclosure).

[0045] We will now describe with reference to Figure 7 the circulation of the different air flows during the decontamination treatment with the embodiment of the cabinet 10 illustrated in Figures 1 to 5, the structure of which has just been described in detail.

[0046] The fresh air ANF sucked in from the outside by the motor-driven fan 50 via the intake vents 36 is mixed with the recycled air ARC sucked in from inside the enclosure 30, then heated and recharged with ozone by the heating element 52 and the ozone generators 54 to produce a flow of pulsed air under ozonated and heated pressure APL. It will be noted that fresh air ANF can also be admitted from the outside via the intake vents 38 formed in the door 32, due to the depression created in the enclosure 30 by the air suction produced by the motor-driven fan 50 via the intake vents 44.

[0047] The pulsed air discharged by the motor-driven fan 50 is sent into the collectors 42 over the entire length where these extend in the upper part 34 of the enclosure, from their upper part 56 at the level of the technical block 26 to the various diffusion vents 40 located in the lower part 32 of the enclosure.

[0048] These diffusion vents 40 can, as illustrated in particular in Figure 2, be distributed on the vertical bottom wall 14 of the cabinet but also, as a variant or in addition, on the floor wall 18, as illustrated at 68 in Figure 7. In the latter case, the floor 18 is a double-walled floor and the intermediate space between its two walls is in communication with the lower end of the collector 42, for allow the APL pulsed air to reach the floor diffusion vents 68.

[0049] The pulsed air APL delivered by the intake vents 40 and / or 68 will then circulate in the enclosure 30, under the dual effect of suction through the suction vents 44 located at the opposite, upper end of the enclosure and natural convection of the hot air upwards. In contact with the effects to be treated, the pulsed air will then become loaded with contaminants (contaminated air ACT in the figures) and gradually cool. If the effects to be treated are still wet, the humidity extracted by the rising hot air flow will, in the opposite direction, naturally descend towards the bottom of the cabinet where the water can condense, so that the contaminated air ACT reaching the top of the enclosure before being sucked in for recirculation (air flow to be recycled ARC) will generally not be saturated with humidity, the latter having fallen back towards the lower areas of the enclosure.

[0050] This produces a continuous mixing of the air inside the enclosure, which is particularly favorable to the decontamination process throughout the duration of the process, with a minimum of turbulence which would be likely to slow down the initial phenomenon of adsorption without reaction explained above (Langmuir-Hin-shelwood mechanism).

[0051] Furthermore, a generally laminar air circulation flow, from bottom to top, makes it possible to reduce thermal losses with the walls of the cabinet, which is an obvious advantage in terms of overall energy consumption and therefore the final cost of decontamination.

[0052] Figures 8 and 9 illustrate a second embodiment of the enclosure of the invention, making it possible to further improve the overall thermal balance of the decontamination treatment.

[0053] The structure and operation of this variant are essentially the same as those of the first embodiment described above with reference to Figures 1 to 5 and 7, and only the elements which differ will be described.

[0054] The vertical bottom wall 14 of the cabinet here comprises a triple wall 70, 72, 74, extending in width at least over the width of the collectors 42 and in height preferably over the entire extent of the enclosure between the floor wall 18 and the technical block 26, at the level of the element 56 receiving the ozonated and heated APL pulsed air flow.

[0055] The triple wall 70, 72, 74 defines two adjoining parallel sheaths 76, 78 with: - an internal sheath 76 on the inside of the enclosure, and - an external sheath 78 on the outside of the cabinet.

[0056] The internal sheath 76 constitutes a connecting conduit from the air treatment unit to the diffusion vents 40, conveying the pulsed air flow APL downwards.

[0057] The external sheath 78 may, in a first variant, constitute a static layer of thermal insulation (simple static air blade or filling of an insulating material) interposed between the internal sheath 76 carrying the pulsed hot air APL and the external environment of the enclosure, which is at room temperature. This greatly limits thermal losses along the pulsed air collectors 42 throughout the region where the ozonated hot air, the temperature of which can reach 40 or 50°C, or even 60°C, is conducted without being diffused.

[0058] In a second, preferred variant, corresponding to the illustrations of Figures 8 and 9, the external sheath 78 forms a conduit conveying upwards to the air treatment unit 26 a flow of fresh air ANF sucked from below the cabinet by air intake vents 80 located in the lower part thereof. The fresh air ANF intake vents 80 are for example, as illustrated, located in the base of the cabinet 10, advantageously replacing the front intake vents 36 and / or the door intake vents 38 of the previous embodiment, the operation of which was described in Figure 7.

[0059] The two adjoining ducts form between them a heat exchanger, where the rising flow of cold fresh air ANF drawn into the external duct 78 from below the cabinet by the intake vents 80 is progressively heated, through the intermediate wall 72, by the descending flow of hot pulsed air APL discharged by the motor-driven fan 50 into the internal duct 76 to the diffusion vents 40 (which, in the example illustrated in Figure 8, are vents formed in the floor 18 of the enclosure).

Claims

1. Claims A decontamination cabinet (10) suitable for the degradation of polycyclic aromatic hydrocarbons and / or the destruction of microorganisms present on contaminated effects, comprising: - a closed enclosure (30) extending in height and intended to receive effects to be decontaminated, defined by vertical walls (12, 12, 14, 16) including a door (16), and by a floor wall (18) and a ceiling wall (20) of the cabinet; - fresh air intake means (36, 38, 80), communicating with the exterior of the cabinet and with the interior volume of the enclosure (30); and - an air treatment unit (50, 52, 54), comprising a first motor-fan (50) in upstream and downstream communication with the interior volume of the enclosure and with at least one ozone generator (54) and at least one heating element (52), so as to create inside the enclosure a flow of pulsed air (APL) coming into contact with the contaminated effects, characterized in that: - the pulsed air (APL) is ozonated by the air treatment unit (50, 52, 54) to an ozone content of between 0.5 and 3 ppm, in that: - the closed enclosure defining in height an upper part (34) and a lower part (32), at least one of the vertical walls of the cabinet and / or the floor wall of the cabinet comprises diffusion vents (40) diffusing the pulsed air (APL) and located at the level of said lower part (32) of the enclosure; and - the cabinet comprises at least one pulsed air collector (30) extending along said upper part of the enclosure, and connecting the air treatment unit (50, 52, 54) to the diffusion vents (40), so as to receive the pulsed air flow (APL) produced by the air treatment unit to diffuse it at said lower part (32) of the enclosure via the diffusion vents (40) and produce in the enclosure a generally laminar air circulation flow, from bottom to top, and in that: - the cabinet further comprises an extraction unit (62, 64, 66) with a second motor-driven fan (62) connected at the inlet to air extraction vents (60) located on the ceiling wall (20) of the cabinet and, at the outlet, to a chimney (64) for evacuation to the outside atmosphere, the extraction unit (62, 64, 66) being capable of i) extracting from the enclosure a fraction (AEX) of the contaminated air (ACT) loaded with ozone and particles, ii) filtering this fraction (AEX) of the extracted contaminated air (ACT), and iii) rejecting this fraction of filtered air outside the cabinet.

2. The decontamination cabinet of claim 1, wherein the fresh air intake means comprise intake vents (36, 38, 80) located on a vertical wall (14) of the cabinet in the lower part of the enclosure, and / or in the floor wall (18) of the cabinet.

3. The decontamination cabinet of claim 1, further comprising in the ceiling wall (20) and / or near the ceiling wall (20) suction vents (44) located upstream of the motor-driven fan, for the recirculation (ARC) of the contaminated air (ACT), in particular hot air not saturated with humidity.

4. The decontamination cabinet of claim 3, wherein at least one of the suction vents (44) is provided with a disinfecting and / or deodorizing cassette (58).

5. The decontamination cabinet of claim 1, wherein at least one of the vertical walls (14) of the cabinet forms a wall of the pulsed air collector (42).

6. The decontamination cabinet of claim 5, wherein the pulsed air collector (42) comprises a triple wall (70, 72, 74) defining two ducts (76, 78) extending parallel over at least part of the collector, with: - on the inside of the enclosure, an internal duct (76) forming a connecting conduit from the air treatment unit (50, 52, 54) to the diffusion vents (40) and conveying the pulsed air flow (APL) downwards, and - on the outside of the cabinet, an external duct (78) forming a static thermal insulation layer.

7. The decontamination cabinet of claim 5, wherein the pulsed air collector (42) comprises a triple wall (70, 72, 74) defining two ducts (76, 78) extending parallel over at least a portion of the collector, with: - on the inside of the enclosure, an internal duct (76) forming a conduit connecting the air treatment unit (50, 52, 54) to the diffusion vents (40) and conveying the pulsed air flow (APL) downwards, and - on the outside of the cabinet, an external duct (78) forming a conduit connecting fresh air intake vents (80) to the air treatment unit (50, 52, 54) and conveying a fresh air flow upwards (ANF), - the two adjoining ducts forming a heat exchanger between the heated pulsed air flow (APL) leaving the air treatment unit (50, 52, 54) and the fresh air flow (ANF) entering the air treatment unit (50, 52, 54).

8. The decontamination cabinet of claim 1, wherein the extraction and filtering unit further comprises: - an active filter (66), and wherein the second motor-driven fan (66) is in communication with the interior volume of the enclosure (30) and with the active filter (66) to bring towards the active filter, before discharge outside the cabinet through the chimney, said fraction of contaminated air loaded with ozone (ACT).

9. The decontamination cabinet of claim 1, wherein the lower portion (32) of the enclosure (30) receiving the pulsed air flow (APL) produced by the air treatment unit (50, 52, 54) extends over 30% to 70%, preferably 40% to 60%, of the total height of the interior volume of the enclosure (30).

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