Photochemical degradation process using ethylene

Description

Field of invention

[0001] The present invention relates to a method for photochemically degrading ethylene in the far UV range for use with climacteric fruit, vegetable, and / or cut flower storage and preservation chambers. Background to the invention

[0002] Fruit ripening refers to the set of biological and physiological changes that result in a fruit reaching maturity and giving it specific organoleptic properties, such as texture, color, or odor. Ripening is ethylene-dependent and is associated with an increase in cellular respiration in its tissues. For a climacteric fruit, a respiration peak is associated with a peak in ethylene production. For climacteric fruits, the ethylene production peak is partly responsible for fruit ripening. Climacteric fruits are therefore capable of ripening after being picked. Thus, these fruits can be harvested green and ripen during the storage period. Non-climacteric fruits, on the other hand, must ripen on the vine and are not capable of autonomous ripening.The most well-known climacteric fruits are: banana, apple, pear, kiwi, tomato, melon, peach, apricot and avocado.

[0003] The adaptation of French climacteric fruit production to a globalized market and the increasing specialization of farms have led producers and shippers to develop fruit storage and preservation systems, in order to spread the annual supply up to 10 months after harvest. The preservation of climacteric fruits is possible thanks to the storage of these fruits in cold rooms (0-4°C) and under a controlled atmosphere (AC: 2-3% O 2 , 1-5% CO 2 , ULO: 1.2 - 1.8% O 2 , 1 - 2% CO 2 or XLO: 0.7 - 1% O 2 , 0.6 - 1.2% CO 2 ) to slow down respiration and therefore fruit ripening, and maintain the organoleptic properties of said fruits (firmness, acidity, fruit coloring). Climacteric fruits are placed in a cold room and under a controlled atmosphere as quickly as possible. The controlled gaseous atmosphere is obtained in a few days by immediate injection of nitrogen and extraction of CO2 as soon as the oxygen has been reduced to a few %.

[0004] The apple is a climacteric fruit whose ripening is accompanied by significant ethylene production (which varies depending on the variety, early and late). Apples intended for storage are therefore harvested before the climacteric peak, as soon as ethylene production begins. At this time, ethylene production is very low, but the fruit is able to ripen after detachment from the tree, because this low level stimulates another ethylene production system, called autocatalysis, which will accelerate the ripening process. However, in storage rooms, even if the respiration of the fruit is slowed down by the cold and the controlled atmosphere, and if pre-climacteric ethylene production is low, there is an accumulation of ethylene due to the large quantity of confined fruit.This accumulation of ethylene, which can reach several hundred ppm, accelerates the ripening of apples through the process of autocatalysis, and promotes the appearance of certain fungal and physiological diseases. It is therefore essential to be able to correctly control the level of ethylene in cold rooms.

[0005] To control the ethylene concentration, different processes are currently used, such as adsorption on activated carbon, thermal oxidation with or without precious metal catalysis, or oxidation by potassium permanganate present in the form of crystals or impregnated on various materials. However, these processes have a high operating cost, particularly energy costs, and their performance is such that the ethylene concentration in the controlled atmosphere is not always satisfactory. In addition, these processes must be stopped frequently because it is necessary to replace or regenerate the active compounds (adsorbent, catalyst, or oxidant).

[0006] Other processes, such as Smartfresh TM treatment, use chemical reagents applied directly to the fruit. These processes can be effective but are expensive, and their implementation on all stored fruit remains difficult to achieve. In addition, these devices are not authorized for organic farming, and they can have unwanted side effects (browning of certain apple varieties).

[0007] A process consisting of reducing the O2 content as much as possible (<0.7%) of the controlled atmosphere of the storage chamber without inducing fermentation of the fruit is currently commercially available. However, this process is expensive and requires fine regulation and therefore excellent sealing of the storage chamber, which is not always possible in the case of old installations.

[0008] Various processes for degrading accumulated ethylene using catalytic processes have been developed and some are currently commercially available. However, these processes, which require the use of a catalyst, have disadvantages that can vary depending on the catalyst used. For example, some processes are very energy-intensive because the catalyst must be continuously heated between 200°C and 250°C to be active. This results in heating the atmosphere withdrawn from the storage chamber to treat it. This atmosphere must then be cooled to between 0°C and 4°C before being reintroduced into the storage chamber. In addition, after degradation of ethylene by this type of catalytic process, the residual ethylene concentration is not satisfactory for storing apples.Other catalytic processes involve photocatalysts such as TiO 2 but several technological constraints make their implementation complex with insufficient efficiencies.

[0009] Pathak Namrata et al. ("Effect of process variables on ethylene removal by vacuum ultraviolet radiation: application in fresh produce storage", Biosystems Engineering, Academic Press, UK, vol. 159, May 8, 2017, pages 33-45) describes a reactor used to decrease the concentration of ethylene in a gas.

[0010] Pathak Namrata et al. ("Photocatalytic and photochemical oxidation of ethylene: potential for storage of fresh produce - a review", Food and Bioprocess Technology, an international journal, Springer-Verlag, New York, vol. 10, no. 6, February 20, 2017, pages 982-1001) describes the use of photochemical and photocatalytic oxidation of ethylene for the preservation of fresh produce.

[0011] There is therefore a need for a process for degrading ethylene accumulated in a climacteric fruit storage chamber that is efficient throughout the period of storage of the fruit in the storage chamber and that is energy-efficient.

[0012] Surprisingly, the Applicant has found a process that meets this need.

[0013] The invention therefore relates to a method for photochemically treating a gaseous atmosphere of a closed enclosure comprising ethylene, said method being implemented in an installation comprising a reactor and the sealed closed enclosure and storing fruit, vegetables and / or cut flowers at temperatures of 0°C to 15°C under the gaseous atmosphere, said reactor comprising: a side wall having a cylindrical shape along an axis of revolution (Ox) and two front walls, the side wall and the front walls delimiting an internal reaction space, a gas inlet port and a gas outlet port, and a source of ultraviolet radiation in the internal reaction space, said storage chamber being fluidically connected to the gas inlet port and to the gas outlet port of the reactor, the installation being characterized in that the ultraviolet radiation source emits radiation in the far ultraviolet whose spectral range is between 160 nm and 180 nm and has a variable power, in particular from 10 W to 500 W, and in that the gas inlet port comprises a part formed by a cylindrical conduit of which a generator is tangent to a cross-section of the side wall and allows a tangential introduction of a gaseous atmosphere into the internal reaction space to create a swirling flow of the gaseous atmosphere in the internal reaction space for a flow rate of the gaseous atmosphere in the internal reaction space of the reactor of 60 m 3 < / h to 150 m 3 < / h; said method comprising at least one cycle comprising the following steps: a) withdrawing the gaseous atmosphere from the closed enclosure,a1) introducing the gaseous atmosphere comprising ethylene into the internal reaction space (4) of the reactor (1) via the gas inlet port (5) with a flow rate of gaseous atmosphere in the internal reaction space (4) of the reactor (1) of 60 m 3 < / h to 150 m 3 < / h so as to create the turbulent flow characterized by a Reynolds number greater than 5000 and by a non-zero vortex intensity of the gaseous atmosphere in the internal reaction space (4) of the reactor (1), b) treating the gaseous atmosphere to obtain a treated gaseous atmosphere, b1) extracting the treated gaseous atmosphere via the gas outlet port (6), c) introducing the treated gaseous atmosphere into the closed enclosure, characterized in that the treatment step b) is a step of photochemical degradation of ethylene carried out by the ultraviolet radiation source and in which the residence time in the internal reaction space (4) of the reactor (1) is from 0.05 s to 60 s,in particular from 0.10 s to 25 s, especially from 0.15 s to 0.35 s. ,

[0014] This process makes it possible to degrade ethylene from a gaseous atmosphere so that, at the outlet of the reactor, the ethylene concentration in the gaseous atmosphere is less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These very low ethylene concentration values ​​are particularly suitable for the preservation of climacteric fruits, vegetables and cut flowers, in particular apples and kiwis.

[0015] Advantageously, these very low ethylene concentration values ​​in the gaseous atmosphere at the outlet of the reactor can be maintained continuously for approximately 1 year, i.e. throughout the storage period of the fruit in the storage chamber, and without any particular maintenance of the reactor of the invention.

[0016] Furthermore, thanks to the variable power of the ultraviolet radiation source, it is possible to adjust the power of the radiation emitted in the far ultraviolet to the flow of ethylene introduced or present in the internal reaction space of the reactor.

[0017] This adjustment helps reduce the energy consumption of the ultraviolet radiation source and preserve its lifespan.

[0018] This power adjustment also makes it possible to adjust the ethylene concentration in the storage chamber and therefore to control the ripening kinetics of the fruits, vegetables and / or cut flowers stored in this storage chamber.

[0019] In addition, the operation of the reactor according to the invention does not require heating, it is therefore energy-efficient, and in particular less energy-consuming than the operation of a catalysis reactor which must be continuously heated to the activation temperature of the catalyst. Figures

[0020] There Figure 1 is an axonometric projection schematically illustrating an ethylene degradation reactor according to the present invention. The Figure 2a is a projection schematically illustrating a cross-section along the axis (Ox) of an orthogonal reference frame (O, x, y, z) of the ethylene degradation reactor according to the present invention. The Figure 2b is a section along the AA' axis of the Figure 2a . There Figure 3 is a projection schematically illustrating a cross-section along the axis (Ox) of an orthogonal reference frame (O, x, y, z) of an embodiment of the ethylene degradation reactor according to the present invention. The Figure 4ais a projection schematically illustrating a cross-section along the axis (Ox) of an orthogonal reference frame (O, x, y, z) of the ethylene degradation reactor according to the present invention. For reasons of simplicity, the side wall of the reactor has a right circular cylindrical shape. The Figure 4b is a section along the AA' axis of the Figure 4a . There Figure 5 is a graph illustrating the decrease over time of the ethylene concentration in the gaseous atmosphere of a closed enclosure, the gaseous atmosphere being treated in an ethylene degradation reactor according to the present invention. Figure 6 is a graph illustrating the decrease over time of the ethylene concentration in the gaseous atmosphere of an industrial storage chamber, the gaseous atmosphere being treated in an ethylene degradation reactor according to the present invention. Detailed description

[0021] The present invention is described with reference to Figures 1 to 4b . For simplicity, the side wall of the reactor of the present invention is illustrated with a right circular cylindrical shape.

[0022] The method of the invention uses a reactor 1 including: a side wall 2 having a cylindrical shape along an axis of revolution (Ox) and two front walls 3a And 3b , the side wall 2 and the front walls 3a And 3b delimiting an internal reaction space 4 , a gas inlet port 5 and a gas outlet port 6 , and a source of ultraviolet radiation 7 in the internal reaction space 4 , characterized in that the ultraviolet radiation source 7 emits radiation in the far ultraviolet whose spectral range is between 160 nm and 180 nm and has a variable power, in particular from 10 W to 500 W, and in that the gas inlet port 5 comprises a part formed by a cylindrical conduit, one generator of which is tangent to a cross-section of the side wall 2 and allows a tangential introduction of a gaseous atmosphere into the internal reaction space 4 to create a vortex flow of the gaseous atmosphere in the internal reaction space 4 for a flow rate of the gaseous atmosphere in the internal reaction space (4) of the reactor (1) of 60 m 3 < / h to 150 m 3 < / h.

[0023] For the purposes of the present invention, the term "wall having a cylindrical shape" means a wall in the general shape of a cylinder, a cylinder being a surface generated by a straight line which moves parallel to an axis of revolution (Ox), resting on two fixed planes. Typically, the cylinder may be a prism with a polygonal base such as a prism with a triangular base, a square base or a rectangular base. The cylinder may also be a circular cylinder, in particular a right circular cylinder characterized by a radius r and a height h . According to a specific embodiment the cylinder is a circular cylinder so that the wall has a right circular cylindrical shape.

[0024] For the purposes of the present invention, the term "internal reaction space" means the internal part of the reactor 1 , that is, the volume between the side wall 2 and the two front walls 3aAnd 3b .

[0025] For the purposes of the present invention, the term "gas inlet port" means any element suitable for introducing a gaseous atmosphere into the internal reaction space. 4 of the reactor 1 .

[0026] For the purposes of the present invention, the term "gas outlet port" means any element adapted to extract a gaseous atmosphere from the internal reaction space. 4 of the reactor 1 .

[0027] Typically the gas inlet port 5 is suitable for connection to a gas line, e.g., the gas inlet port 5 could be a gas connection.

[0028] Typically the output port of 6 is suitable for connection to a gas line. For example, the gas outlet port 6 could be a gas connection.

[0029] For the purposes of the present invention, the term "gaseous atmosphere" means a mixture comprising different gaseous compounds, in particular comprising a mixture of nitrogen (N 2 ), carbon dioxide (CO 2 ), oxygen (O 2 ), water (H 2 O) and ethylene (C 2 H 4 ). Typically, the gaseous atmosphere may be a controlled storage chamber gaseous atmosphere comprising from 0.7% to 3% O 2 , from 1% to 5% CO 2 , from 80 to 100% relative humidity (RH) of H 2 O, and less than 300 ppm of ethylene, the remainder being mainly nitrogen (N 2 ).

[0030] For the purposes of the present invention, "storage chamber" means a closable enclosure adapted to be watertight and to store fruits, such as climacteric fruits, vegetables and / or cut flowers at temperatures of 0°C to 15°C, in particular of 0°C to 4°C in a gaseous atmosphere.

[0031] For the purposes of the present invention, the term "climacteric fruit" means a fruit whose ripening is dependent on ethylene. The best-known climacteric fruits are: banana, apple, pear, kiwi, tomato, melon, peach, apricot and avocado.

[0032] For the purposes of the present invention, "radiation emitted in the far ultraviolet (also referred to as far UV)" means radiation whose spectral range is between 160 nm and 180 nm.

[0033] Advantageously, the radiation emitted in the far UV allows the photochemical degradation of ethylene.

[0034] For the purposes of the present invention, the term "photochemical degradation (also referred to as degradation by photochemical means)" means all the chemical reactions allowing the decomposition of a chemical compound by light, ie by photolysis and / or by its reaction with photo-induced species, such as radicals or ozone.

[0035] Without being bound by any theory, the inventors are of the opinion that the photochemical degradation of ethylene is carried out by the photolysis of ethylene and by the oxidation of ethylene with ozone and photo-induced radicals, such as OH •< .

[0036] Compared to the catalytic process, photochemical degradation is particularly advantageous because it does not require the use of a solid catalyst. Photochemical degradation is also less energy-intensive because it is not necessary to maintain this catalyst at its activation temperature.

[0037] For the purposes of the present invention, the term "ultraviolet radiation source" means a source emitting radiation in the far UV which may be of generally cylindrical shape, that is to say that it comprises an external side wall having a cylindrical shape along an axis of revolution and two external front walls and whose material is transparent to the radiation emitted in the far UV.

[0038] For the purposes of the present invention, "power" means the radiant power of the UV radiation emitted by the ultraviolet radiation source. 7 .

[0039] Typically, the gaseous atmosphere comprising ethylene is introduced into the internal reaction space 4 of the reactor 1 via the gas inlet port 5 The gaseous atmosphere is then subjected to the radiation emitted in the far UV emitted by the ultraviolet radiation source 7The radiation emitted in the far UV allows the photochemical degradation of ethylene in the gaseous atmosphere. The gaseous atmosphere thus treated is then extracted from the internal reaction space 4 of the reactor 1 via the gas outlet port 6 .

[0040] Typically, at the reactor outlet 1 , the ethylene concentration in the treated gaseous atmosphere is less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These low ethylene concentration values ​​are particularly suitable for the preservation of climacteric fruits, vegetables and cut flowers, in particular apples and kiwis.

[0041] As also explained previously, the use of the reactor 1according to the invention is energy-efficient, and in particular less energy-consuming than a catalysis reactor, because it can be used without being heated and because the power of the ultraviolet radiation source 7 is variable.

[0042] According to one embodiment, the reactor 1 according to the invention may further comprise a programmer adapted to vary the power emitted by the ultraviolet radiation source 7.

[0043] According to a particular embodiment, illustrated by the Figures 1 to 4 , the side wall 2 may have a straight cylindrical shape.

[0044] Typically, when the side wall 2 has a right circular cylindrical shape, its radius r is less than 500 mm, in particular from 10 mm to 250 mm, especially from 25 mm to 200 mm, and even more particularly from 50 mm to 100 mm, and its height his less than 2000 mm, in particular from 500 mm to 750 mm, especially from 600 mm to 650 mm, and even more particularly from 615 mm to 625 mm.

[0045] According to one embodiment, the two ports 5 And 6 are positioned on the side wall 2 .

[0046] According to one embodiment, one of the two ports is positioned on the side wall 2 and the other port is positioned on a front wall 3a Or 3b .

[0047] According to one embodiment, the gas inlet port 5 and the gas outlet port 6 are positioned on the same front wall 3a Or 3b .

[0048] According to one embodiment, one of the two ports is positioned on one of the two front walls and the other port is positioned on the other front wall.

[0049] According to a specific embodiment, the gas inlet port 5 and the gas outlet port 6 can be positioned at opposite ends of the reactor 1 .

[0050] As illustrated by the Figures 2b And 4b , the gas inlet port 5 comprises a part formed by a cylindrical conduit, in particular a right circular cylindrical conduit, one generator of which is tangent to a cross-section of the side wall 2 .

[0051] The gas inlet port 5 allows a tangential introduction of the gaseous atmosphere into the internal reaction space 4 thus creating a vortex flow of the gaseous atmosphere in the internal reaction space 4 .

[0052] For the purposes of the present invention, "vortex flow" means a turbulent flow characterized by a Reynolds number greater than 5000 and by a non-zero vortex intensity.

[0053] The vortex flow maximizes the renewal of the gaseous atmosphere near the source of ultraviolet radiation 7 and to maximize the residence time of the gaseous atmosphere in the interior reaction space 4 Advantageously, this vortex flow allows the photochemical degradation of ethylene to be maximized.

[0054] The person skilled in the art will be able to adapt the dimensions of the part formed by the cylindrical conduit of the gas inlet port 5 and the flow rate of the gas atmosphere to maximize the vortex flow in the internal reaction space 4 .

[0055] According to one embodiment, illustrated by the Figures 2b And4b , the gas outlet port 6 may comprise a part formed by a cylindrical conduit, in particular a right circular cylindrical conduit, one generator of which is tangent to a cross-section of the side wall 2 .

[0056] A gas outlet port 6 according to this embodiment makes it possible to maximize the swirling flow of the gaseous atmosphere in the internal reaction space 4 .

[0057] The person skilled in the art will be able to adapt the dimensions of the part formed by the cylindrical conduit of the gas outlet port 6 and the flow rate of the gas atmosphere to maximize the vortex flow in the interior reaction space 4 .

[0058] According to one embodiment, the reactor 1 may also include means for maximizing vortex flow in the interior reaction space 4 .

[0059] Typically the reactor 1 may also include fixing means adapted to fix the ultraviolet radiation source 7 in the internal reaction space 4 . Typically the front walls 3a And 3b of the reactor 1 include these means of fixing.

[0060] According to one embodiment, illustrated in the Figures 1 to 4 , the ultraviolet radiation source 7 comprises an external wall having a right circular cylindrical shape.

[0061] According to this embodiment, the radius of the outer wall of the ultraviolet radiation source 7 is greater than 1 mm, in particular from 10 mm to 50 mm, especially from 20 mm to 25 mm, and its height is less than 2000 mm, in particular from 500 mm to 750 mm, especially from 600 mm to 650 mm, and even more particularly from 615 mm to 625 mm.

[0062] As illustrated on the Figures 1 to 2b , when the side wall 2 has a right cylindrical shape and the external wall of the ultraviolet radiation source 7 has a right circular cylindrical shape, then their axes of revolution can be merged. Advantageously, this makes it possible to homogenize the photochemical degradation of ethylene.

[0063] For the purposes of the present invention, the term "air gap" refers to the distance between the side wall 2 and the outer wall of the ultraviolet radiation source 7 in the plane orthogonal to the axis of revolution (Ox). The air gap "e" is illustrated on the Figure 2a .

[0064] According to a specific embodiment, the air gap is from 1 mm to 499 mm, in particular from 10 mm to 250 mm, more particularly from 20 mm to 100 mm, most particularly 39 mm.

[0065] Advantageously, an air gap in these value ranges makes it possible to maximize the absorption of radiation emitted in the far UV within the reaction medium (the gaseous atmosphere present in the internal reaction space 4 ) and therefore maximize the photochemical degradation of ethylene.

[0066] The ultraviolet radiation source 7 emits ultraviolet radiation whose spectral range is from 160 nm to 180 nm, more particularly from 165 nm to 175 nm.

[0067] According to a very particular embodiment, the source of ultraviolet radiation 7 emits ultraviolet radiation whose spectral range is only from 160 nm to 180 nm, more particularly only from 165 nm to 175 nm.

[0068] Typically, an ultraviolet radiation source 7 may emit continuous radiation in the far UV or emit radiation in the far UV over one or more of the previously mentioned spectral ranges. An ultraviolet radiation source 7 may also emit radiation in the far UV having one or more wavelengths of the previously mentioned spectral ranges.

[0069] According to a very specific embodiment, the ultraviolet radiation source 7 emits ultraviolet radiation with a wavelength of 172 nm.

[0070] The absorption spectrum of ethylene shows an absorption maximum at 170 nm. Advantageously, the above-mentioned spectral ranges and wavelength enable photochemical degradation of ethylene with high quantum efficiency.

[0071] According to one embodiment, the variable power emitted by the ultraviolet radiation source 7 is 12W to 100W, especially 15W to 50W.

[0072] Advantageously, a power within the ranges indicated above makes it possible to obtain a good ratio between the flow of ethylene degraded by photochemical means and the energy cost of this photochemical degradation.

[0073] Ozone is a product generated by the photochemical degradation of ethylene when the gaseous atmosphere is subjected to radiation emitted in the far UV range emitted by the ultraviolet radiation source 7. Its presence can be positive for the conservation of climacteric fruits, such as apples (sanitary effect on the spores present on the surface of the fruits), but can pose safety problems and damage to the equipment included in the storage rooms. To control the ozone concentration in the extracted gaseous atmosphere, the reactor 1 according to the invention may comprise an ozone removal module fluidically connected to the gas outlet port 6 .

[0074] Typically this ozone removal module may include an adsorbent compound capable of decomposing ozone into oxygen such as a zeolite or activated carbon.

[0075] According to a particular embodiment, illustrated by the Figure 3 , the reactor 1 can understand n ultraviolet radiation sources 7 positioned along the axis of revolution (Ox) of the reactor 1 , nbeing an integer greater than or equal to 2, in particular from 2 to 50, very particularly from 2 to 10.

[0076] According to a particular embodiment, illustrated by the Figures 4a and 4b , the reactor 1 can understand m sources of ultraviolet radiation 7 in a plane (O, y, z) orthogonal to the axis of revolution (Ox), m being an integer greater than or equal to 2, in particular from 2 to 50, very particularly from 2 to 10.

[0077] Multiply sources of ultraviolet radiation 7 in the internal reaction space 4 allows the dimensions of the reactor to be adapted 1 to the volume of gaseous atmosphere to be treated.

[0078] According to this embodiment, the distance between two of the m sources of ultraviolet radiation 7 is less than or equal to twice the air gap, e.

[0079] Advantageously, such a distance between two of the msources of ultraviolet radiation 7 allows to maximize the use of the radiation emitted in the far UV and therefore maximize the photochemical degradation of ethylene.

[0080] Typically the distance between two of the m ultraviolet radiation sources 7 is 2 mm to 200 mm, in particular 20 mm to 150 mm, more particularly 40 mm to 100 mm, most particularly 78 mm.

[0081] Use of the reactor 1 according to the invention is particularly advantageous when the reactor 1 according to the invention is fluidically connected to a storage chamber.

[0082] The method of the invention uses an installation comprising the reactor 1 as described above and a storage chamber, the storage chamber being fluidically connected to the gas inlet port 5 and to the gas outlet port 6 of the reactor 1 .

[0083] Typically the reactor 1 is present outside the storage chamber. The reactor 1 can also be present in the storage room. This helps to reduce the space requirement of the installation, for example on a ship or in an airplane transporting fruits, such as climacteric fruits, vegetables and cut flowers.

[0084] The storage chamber and the reactor 1 operate in a closed loop. Thus the controlled gaseous atmosphere of the storage chamber comprising ethylene is continuously or sequentially withdrawn from the storage chamber to be introduced into the internal reaction space 4 of the reactor 1 via the gas inlet port 5 . In the internal reaction space 4, the controlled gaseous atmosphere is subjected to the radiation emitted in the far UV emitted by the ultraviolet radiation source 7. Thanks to the radiation emitted in the far UV, the ethylene in the controlled gaseous atmosphere is degraded photochemically. The controlled gaseous atmosphere thus treated is then extracted from the internal reaction space 4 of the reactor 1 via the gas outlet port 6 and is reintroduced continuously or sequentially into the storage chamber. At the reactor outlet 1 , the ethylene concentration in the treated controlled gaseous atmosphere is typically less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm.

[0085] As explained below, this closed-loop operation makes it possible to reduce the ethylene concentration in the controlled gaseous atmosphere of the storage chamber to a threshold value and then to stabilize it at this threshold value while ethylene can be regularly produced by the fruits and / or cut flowers present in the storage chamber.

[0086] After the introduction of the fruits, vegetables and / or cut flowers to be stored in the storage chamber and the closing of the storage chamber, the controlled gas atmosphere of the storage chamber is obtained by lowering the oxygen (O 2 ) content and then by immediate injection of nitrogen (N 2 ) and extraction of CO 2 . Typically, the initial ethylene concentration in the controlled gas atmosphere of the storage chamber is less than 300 ppm.

[0087] Photochemical degradation of ethylene from the controlled gas atmosphere into the internal space4 of the reactor 1 will lower the ethylene concentration in the controlled gas atmosphere of the storage chamber from the initial value to the threshold value. Then, once the threshold value is reached, the ethylene concentration in the controlled gas atmosphere of the storage chamber will stabilize at the threshold value thanks to the photochemical degradation of the ethylene in the controlled gas atmosphere in the internal space 4 of the reactor 1 .

[0088] The threshold value is typically less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These low values ​​are particularly suitable for the preservation of climacteric fruits, vegetables and cut flowers, in particular apples and kiwis. Therefore, the installation according to the invention is particularly suitable for the preservation of climacteric fruits, vegetables and cut flowers, in particular apples and kiwis.

[0089] Advantageously, the installation according to the invention is energy-efficient because, as also explained previously, the variable power of the ultraviolet radiation source 7 can be adjusted to the increasingly lower concentration of ethylene in the controlled gas atmosphere of the storage chamber, and the reactor 1 according to the invention can be used without being heated.

[0090] Typically the installation includes a means adapted to achieve the circulation of the controlled gaseous atmosphere between the storage chamber and the reactor. 1 Typically this means may be a fan, a booster, or a turbine. Typically this means is fluidically connected to the storage chamber and the gas inlet port. 5 or at the gas outlet port 6 .

[0091] The circulation flow in the reactor 1 conditions the rate of renewal of the atmosphere in the storage chamber.

[0092] If the reactor 1 according to the invention comprises the ozone removal module described above, then this module is fluidically connected to the gas outlet port 6 and to the storage room.

[0093] This removal module allows the ozone concentration in the portion of gaseous atmosphere extracted from the internal reaction space to be controlled.4 of the reactor 1 which is reintroduced into the storage chamber. This allows you to benefit from the advantages of the presence of ozone (sanitary effect on the spores present on the surface of the fruit) without having the disadvantages (safety problems and damage to the equipment included in the storage chambers).

[0094] Typically the ozone concentration in the gaseous atmosphere extracted from the internal reaction space 4 of the reactor 1 and reintroduced into the storage chamber is less than 2 ppm, in particular less than 1 ppm, especially 0.2 ppm to 0.5 ppm.

[0095] Also described is the use of an ultraviolet radiation source emitting radiation in the far ultraviolet and having variable power for photochemical degradation.

[0096] The ultraviolet radiation source is as described above in connection with the ultraviolet radiation source 7 of the reactor 1 according to the first aspect of the invention and then again in the installation described previously.

[0097] Thanks to the variable power of the ultraviolet radiation source, it is possible to adjust the power of the radiation emitted in the far UV to the quantity of ethylene to be degraded.

[0098] As explained above, this adjustment makes it possible to reduce the energy consumption of the ultraviolet radiation source and to preserve its lifespan. The method according to the invention is therefore energy-efficient, and in particular less energy-consuming than a catalytic method. This power adjustment also makes it possible to adjust the ethylene concentration in a storage chamber and therefore to be able to control the ripening kinetics of the fruits, vegetables and / or cut flowers stored in this storage chamber.

[0099] The ethylene degradation process according to the invention can be carried out on a gaseous atmosphere comprising less than 300 ppm of ethylene.

[0100] Typically the ethylene concentration in the gaseous atmosphere that has undergone the ethylene degradation process is less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These low ethylene concentration values ​​are particularly suitable for the preservation of climacteric fruits, vegetables and cut flowers, in particular apples and kiwis.

[0101] Also described is a method for degrading ethylene comprising a step of photochemical degradation of ethylene using an ultraviolet radiation source emitting radiation in the far ultraviolet and having a variable power, in particular from 10 W to 500 W.

[0102] The ultraviolet radiation source is as described above in connection with the reactor ultraviolet radiation source 7 1according to the first aspect of the invention and then again in the installation described previously.

[0103] Thanks to the variable power of the ultraviolet radiation source, it is possible to adjust the power of the radiation emitted in the far UV to the quantity of ethylene to be degraded.

[0104] As explained above, this adjustment makes it possible to reduce the energy consumption of the ultraviolet radiation source and to preserve its lifespan. The process according to the invention is therefore energy-efficient, and in particular less energy-consuming than a catalytic process. In addition, this power adjustment makes it possible to adjust the ethylene concentration in a storage chamber and therefore to be able to control the ripening kinetics of the fruits, vegetables and / or cut flowers stored in this storage chamber.

[0105] The ethylene degradation process according to the invention can be carried out on a gaseous atmosphere comprising less than 300 ppm of ethylene.

[0106] Typically the ethylene concentration in the gaseous atmosphere that has undergone the ethylene degradation process is less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These low ethylene concentration values ​​are particularly suitable for the preservation of climacteric fruits, vegetables and cut flowers, in particular apples and kiwis.

[0107] The subject of the invention is a method for the photochemical treatment of a gaseous atmosphere of a closed enclosure comprising ethylene, said method being implemented by the ethylene degradation reactor according to the invention and comprising at least one cycle comprising the following steps: a) withdrawing the gaseous atmosphere from the closed enclosure, such as a storage chamber, in particular a storage chamber for climacteric fruits, vegetables, and / or cut flowers, b) treating the gaseous atmosphere to obtain a treated gaseous atmosphere, c) introducing the treated gaseous atmosphere into the closed enclosure, characterized in that treatment step b) is a step of photochemical degradation of ethylene carried out by a source of ultraviolet radiation emitting radiation in the far ultraviolet whose spectral range is between 160 nm and 180 nm and having a variable power, in particular from 10 W to 500 W.

[0108] The ultraviolet radiation source is as described above in connection with the ultraviolet radiation source 7 of the reactor 1 according to the first aspect of the invention.

[0109] As explained previously, thanks to the variable power of the ultraviolet radiation source allowing the power of the radiation emitted in the far UV to be adjusted to the quantity of ethylene to be degraded, the photochemical treatment method according to the invention is low energy intensive, and in particular less energy intensive than a catalytic method. In addition, this power adjustment makes it possible to adjust the ethylene concentration in the storage chamber and therefore to be able to control the ripening kinetics of the fruits, vegetables or cut flowers stored in this storage chamber.

[0110] Typically when the enclosed enclosure is a storage chamber and climacteric fruits are stored therein, then ethylene can be continuously produced by said climacteric fruits.

[0111] This treatment method according to the invention can be implemented on a gaseous atmosphere comprising less than 300 ppm of ethylene.

[0112] In step a), the gaseous atmosphere comprising ethylene is withdrawn continuously or sequentially from the closed enclosure to be treated in step b).

[0113] During treatment step b), the gaseous atmosphere is subjected to far-UV radiation emitted by the ultraviolet radiation source. By means of the far-UV radiation, the ethylene in the gaseous atmosphere is photochemically degraded. Typically, after step b), the ethylene concentration in the treated gaseous atmosphere is less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These low ethylene concentration values ​​are particularly suitable for the preservation of climacteric fruits and cut flowers, in particular apples and kiwis.

[0114] According to a specific embodiment, step b) can be carried out continuously or sequentially.

[0115] According to this specific embodiment, when the ethylene concentration in the gaseous atmosphere of the closed enclosure is higher than the threshold value mentioned above, step b) can be carried out continuously, then when the ethylene concentration in the gaseous atmosphere of the closed enclosure is lower than the threshold value, step b) can be carried out sequentially. Advantageously, this makes it possible to reduce the energy cost of the process according to the invention and to preserve the lifetime of the ultraviolet radiation source and therefore to reduce the economic cost of the process.

[0116] Typically when step b) is carried out continuously then the operation of the ultraviolet radiation source is continuous.

[0117] Typically when step b) is carried out sequentially then the operation of the ultraviolet radiation source is characterized by an alternation between periods of switching on and off of the radiation source.

[0118] The ultraviolet radiation source emits ultraviolet radiation with a spectral range of 160 nm to 180 nm, more specifically 165 nm to 175 nm.

[0119] According to a specific embodiment, during step b), the ultraviolet radiation source emits ultraviolet radiation whose wavelength is 172 nm.

[0120] The absorption spectrum of ethylene has an absorption maximum at 170 nm. Advantageously, the above-mentioned spectral ranges and wavelength allow photochemical degradation of ethylene with high quantum yield in step b) of the process.

[0121] Typically the duration of processing step b) is from 0.01 s to 36000 s, in particular from 0.05 s to 18000 s, very particularly from 0.10 s to 60 s, more particularly still from 0.15 s to 0.35 s.

[0122] Advantageously, a treatment duration in the ranges mentioned above makes it possible to effectively treat the gaseous atmosphere withdrawn in step a).

[0123] The treated gaseous atmosphere is then introduced continuously or sequentially during step c) into the closed enclosure.

[0124] By repeating the cycle comprising steps a), b and c), the ethylene concentration in the gaseous atmosphere of the closed enclosure will decrease until it reaches a threshold value (transient regime) and then stabilize at this threshold value (steady state). Typically this threshold value is less than 5 ppm, in particular less than 2 ppm, more particularly less than 1 ppm, and even more particularly less than 0.03 ppm. These low values ​​are particularly suitable for the preservation of climacteric fruits and cut flowers, in particular apples and kiwis.

[0125] According to a particular embodiment, during the transient regime, steps a), b) and c) can be carried out continuously. This makes it possible to accelerate the reduction of the ethylene concentration in the gaseous atmosphere of the closed enclosure.

[0126] According to a particular embodiment, during the steady state, steps a), b) and c) can be carried out sequentially depending on the ethylene concentration in the gaseous atmosphere of the closed enclosure.

[0127] According to this particular embodiment, if the ethylene concentration in the gaseous atmosphere of the closed enclosure is less than 10% of the threshold value, in particular 5% of the threshold value, more particularly 1% of the threshold value, then steps a), b) and c) are not carried out, and if the ethylene concentration in the gaseous atmosphere of the closed enclosure is greater than 10% of the threshold value, in particular 5% of the threshold value, more particularly 1% of the threshold value, then steps a), b) and c) are carried out in order to reduce the ethylene concentration in the gaseous atmosphere of the closed enclosure.

[0128] This particular embodiment makes it possible to reduce the energy cost of the process according to the invention, which is advantageous during prolonged implementation (over several months) of the process according to the invention.

[0129] This process for photochemical treatment of a gaseous atmosphere comprising ethylene is carried out by reactor 1 as described above.

[0130] The process for photochemical treatment of a gaseous atmosphere comprising ethylene implemented by reactor 1 comprises: between steps a) and b), a step a1) of introducing the gaseous atmosphere comprising ethylene into the reactor 1 via the gas inlet port 5 with a flow of gaseous atmosphere in the internal reaction space 4 of the reactor 1from 60 m 3 < / h to 150 m 3 < / h so as to create the turbulent flow characterized by a Reynolds number greater than 5000 and by a non-zero vortex intensity of the gaseous atmosphere in the internal reaction space 4 of the reactor 1 , and between steps b) and c), a step b1) of extracting the treated gaseous atmosphere via the gas outlet port 6 .

[0131] If the reactor 1 includes the ozone removal module, then this module is fluidically connected to the gas outlet port 6 and to the closed enclosure and the method comprises, between steps b1) and c), a step b2) of eliminating the ozone produced by the photochemical degradation of ethylene during step b).

[0132] Advantageously, this elimination step b2) makes it possible to control the ozone concentration in the treated gaseous atmosphere which is introduced into the closed enclosure during step c).

[0133] Typically the ozone concentration in the treated gaseous atmosphere which is introduced into the closed enclosure during step c) is less than 2 ppm, in particular less than 1 ppm, especially from 0.2 ppm to 0.5 ppm.

[0134] If the enclosed enclosure is a storage chamber, in particular a climacteric fruit storage chamber, this advantageously allows one to benefit from the advantages of the presence of ozone in the enclosed enclosure (sanitary effect on the spores present on the surface of the fruit) without having the disadvantages (safety problems and damage to the equipment included in the enclosed enclosure).

[0135] The flow rate of gaseous atmosphere in the internal reaction space 4 of the reactor 1 is from 60 m 3 < / h to 150 m 3 < / h.

[0136] Advantageously, a flow rate in the above-mentioned ranges allows a large volume of the gaseous atmosphere to be efficiently treated in the internal reaction space. 4 of the reactor 1 .

[0137] Residence time in the internal reaction space 4 of the reactor 1 is from 0.05 s to 60 s, in particular from 0.10 s to 25 s, especially from 0.15 s to 0.35 s.

[0138] Advantageously, a residence time in the ranges mentioned above makes it possible to effectively treat the gaseous atmosphere introduced into the reactor. 1. Examples Example 1: Experiment on photochemical degradation of ethylene in an experimental chamber.

[0139] The feasibility of photochemical degradation of ethylene in the far UV was first validated in an experimental storage chamber.

[0140] The ethylene degradation reactor 1 used is represented on the diagram of the Figure 1. It includes a side wall 2 having a cylindrical shape along the right circular axis of revolution (Ox) and two front walls 3a and 3b , the side wall 2 and the front walls 3a and 3b delimiting an internal reaction space 4 . The reactor 1 further includes a gas inlet port 5 and a gas outlet port 6 , and a source of ultraviolet radiation 7 in the internal reaction space 4 The air gap is 39 mm.

[0141] The ultraviolet radiation source 7 is a xenon excimer lamp emitting radiation with a wavelength of 172 nm and having a variable power of 10 W to 100 W.

[0142] The reactor 1 is fluidly connected, via the gas inlet port 5 and the gas outlet port 6to the experimental storage chamber whose gaseous atmosphere initially comprises 11.5 ppm of ethylene. has) Experimental conditions

[0143] The temperature in the experimental storage chamber is 2°C and the initial composition of the gaseous atmosphere in the experimental storage chamber is as follows: N 2 : 97.33; O 2 : 1.22%; CO 2 : 0.77%; H 2 O : 95% relative humidity Ethylene : 11.5 ppm.

[0144] The storage room contains 17 tons of apples.

[0145] Throughout the duration of the experiment, the gaseous atmosphere comprising ethylene is continuously withdrawn from the experimental storage chamber and introduced into the reaction space. 4 of the reactor 1 via the gas inlet port 5 . Photochemical degradation of ethylene, in the reaction space 4 is carried out by the ultraviolet radiation source 7The treated gaseous atmosphere is then withdrawn from the reaction space. 4 via the gas outlet port 6 and reintroduced into the experimental storage chamber.

[0146] The ethylene concentration in the gaseous atmosphere of the experimental storage chamber is measured and monitored continuously throughout the duration of the experiment. For this purpose, 500 µl of gaseous atmosphere is withdrawn from the experimental storage chamber every 18 min and its composition is analyzed by a gas chromatograph with an injection loop (Airmo VOC C2-C6, Chromatotec ®<; FID detector, PLOT Al 2 O 3 / Na 2 SO 4 column of 0.53 mm diameter).

[0147] The lamp power is set at 20 W. The flow rate of introduction of the gaseous atmosphere into reactor 1 is 145 m 3 < / h. The residence time in the reaction space 4 of reactor 1 is 0.15 s.

[0148] The experiment is carried out using two lamp lighting modes: continuous lighting mode: the lamp is on for 24 hours, and sequential lighting mode (performed using a programmer controlling the lamp): after the 24 hours of continuous mode, the lamp is off for 2 hours then on for 1 hour, this sequence is repeated eight times before the lamp turns off. b) Experimental results

[0149] The experimental results are illustrated in the Figure 5 .

[0150] During the continuous lighting mode, the variation of the ethylene concentration in the gaseous atmosphere of the experimental storage chamber can be divided into two regimes: a transient regime with a very rapid decrease in the ethylene concentration, in less than 10 h, to reach a threshold value close to 0.1 ppm, a stationary regime, between 10 h and 24 h (end of continuous mode), with stability of the ethylene concentration around the threshold value close to 0.1 ppm,

[0151] During sequential lighting mode: when the lamp is turned off, the ethylene concentration in the gaseous atmosphere of the experimental storage chamber increases and reaches a value above 0.8 ppm; when the lamp is turned on, the ethylene concentration in the gaseous atmosphere of the experimental storage chamber decreases very rapidly to about 0.2 ppm; although this value is higher than the value in continuous lighting mode, it is quite satisfactory; and the maximum value of ethylene concentration in the gaseous atmosphere of the experimental storage chamber increases during the first five repetitions and then stabilizes at 1 ppm. Example 2: Photochemical degradation experiments of ethylene in an industrial storage chamber.

[0152] The reactor 1 of Example 1 is fluidically connected, via the gas inlet port 5 and the gas outlet port 6to a 1000 m3 industrial storage chamber whose gaseous atmosphere initially comprises between 45 ppm and 50 ppm of ethylene. has) Experimental conditions

[0153] The temperature in the industrial storage chamber is 0.4°C and the initial composition of the gaseous atmosphere in the closed enclosure is as follows: N 2 : 97.8%; O 2 : 1.2%; CO 2 : 1.0%; H 2 O : 95% relative humidity Ethylene: 45-50 ppm.

[0154] The storage room contains 17 tons of apples.

[0155] Throughout the experiment, the gaseous atmosphere comprising ethylene is continuously withdrawn from the industrial storage chamber and introduced into the reaction space. 4 of the reactor 1 via the gas inlet port 5 . Photochemical degradation of ethylene, in the reaction space 4 is carried out by the ultraviolet radiation source 7The treated gaseous atmosphere is then withdrawn from the reaction space. 4 via the gas outlet port 6 and reintroduced into the industrial storage chamber.

[0156] The ethylene concentration in the gaseous atmosphere of the industrial storage chamber is measured and monitored continuously throughout the duration of the experiment. For this, 250 ml of gaseous atmosphere is withdrawn from the industrial storage chamber and the ethylene concentration in the withdrawn gaseous atmosphere is measured by an electrocatalytic sensor. The sensor is composed of a nanoporous nafion membrane covered with a layer of gold, the oxidation of ethylene on the membrane releases protons thus making it possible to measure an electric current in the sensor proportional to the ethylene concentration.

[0157] The lamp power is set at 20 W. The flow rate of introduction of the gaseous atmosphere into the reactor1 is 101.5 m 3 < / h. The residence time in the reaction space 4 of the reactor 1 is 0.15 s.

[0158] The experiment is carried out using two lamp lighting modes: continuous lighting mode: the lamp is on for 410 hours, and sequential lighting mode (performed using a programmer controlling the lamp): after the 410 hours of continuous mode, the lamp is off for 60 hours and then on for 20 hours, this sequence is repeated twice. b) Experimental results

[0159] The experimental results are illustrated in the Figure 6 .

[0160] During the continuous lighting mode, the variation of the ethylene concentration in the gaseous atmosphere of the industrial storage chamber can be divided into two regimes: a transient regime with a very rapid decrease in the ethylene concentration in the gaseous atmosphere of the industrial storage chamber, in 250 h, to reach a threshold value of 3.6 ppm, a stationary regime, between 250 h and 410 h (end of continuous mode), with stability of the ethylene concentration in the gaseous atmosphere of the industrial storage chamber around the threshold value of 3.6 ppm,

[0161] During sequential lighting mode: when the lamp is switched off, the ethylene concentration in the gas atmosphere of the industrial storage chamber increases to 10 ppm; when the lamp is switched on, the ethylene concentration in the gas atmosphere of the industrial storage chamber decreases very rapidly to about 5 ppm.

[0162] Throughout the experiment, the ozone concentration in the gaseous atmosphere of the industrial storage chamber is also monitored. As illustrated in the Figure 6 , it is always less than 1 ppm and it decreases when the lamp is turned off. Example 3: Experiment of photochemical degradation of ethylene in an industrial storage chamber containing apples for 8 months.

[0163] The reactor 1 of Example 1 is fluidically connected, via the gas inlet port 5 and the gas outlet port 6 to an industrial storage room with a capacity of 16 tonnes.

[0164] 17,000 kg of apples (Royal Gala variety) are stored in the industrial storage room.

[0165] During the 8 months of experiment, the temperature in the storage chamber is maintained between 0.5°C and 1°C and the gas atmosphere of the storage chamber is controlled to comprise about 1% O 2 , about 0.9% CO 2 , about 97% N 2 and to have 95% relative humidity.

[0166] Throughout the experiment, the gaseous atmosphere comprising ethylene is continuously withdrawn from the industrial storage chamber and introduced into the reaction space. 4 of the reactor 1 via the gas inlet port 5 . Photochemical degradation of ethylene, in the reaction space 4 is carried out by the ultraviolet radiation source 7 The treated gaseous atmosphere is then withdrawn from the reaction space. 4 via the gas outlet port 6 and reintroduced into the industrial storage chamber.

[0167] The ethylene concentration in the gaseous atmosphere of the industrial storage chamber is measured and monitored continuously throughout the duration of the experiment according to the protocol described in Example 2.

[0168] After a rapid decrease, the ethylene concentration in the gaseous atmosphere of the industrial storage chamber is maintained below 0.15 ppm for 8 months. Example 4: Experiment of photochemical degradation of ethylene in an industrial storage chamber containing kiwis for 2 months .

[0169] The reactor 1 of Example 1 is fluidically connected, via the gas inlet port 5 and the gas outlet port 6 to an industrial storage room with a capacity of 16 tonnes.

[0170] 243 tonnes of kiwis (Hayward green kiwi variety) are stored in the industrial storage room.

[0171] During the 2 months of experiment, the temperature in the storage chamber is maintained between 0.5°C and 1°C and the gas atmosphere of the storage chamber is controlled to comprise about 2.5% O 2 , about 3.5% CO 2 , about 94% N 2 and to have 95% relative humidity.

[0172] Throughout the experiment, the gaseous atmosphere comprising ethylene is continuously withdrawn from the industrial storage chamber and introduced into the reaction space. 4 of the reactor 1 via the gas inlet port 5 . Photochemical degradation of ethylene, in the reaction space 4 is carried out by the ultraviolet radiation source 7 The treated gaseous atmosphere is then withdrawn from the reaction space. 4 via the gas outlet port 6 and reintroduced into the industrial storage chamber.

[0173] The ethylene concentration in the gaseous atmosphere of the industrial storage chamber is measured and monitored continuously throughout the duration of the experiment according to the protocol described in Example 2.

[0174] The ethylene concentration in the gaseous atmosphere of the industrial storage chamber is maintained below 0.015 ppm for 2 months.

Claims

1. A process for photochemically treating a gaseous atmosphere of a closed enclosure containing ethylene, said process being implemented in a plant comprising a reactor and the sealed closed enclosure and storing cut fruits, vegetables and / or flowers at temperatures from 0°C to 15°C under the gaseous atmosphere, said reactor (1) comprising: - a side wall (2) having a cylindrical shape according to an axis of revolution (Ox) and two front walls (3a, 3b), the side wall (2) and the front walls (3a, 3b) delimiting a reaction internal space (4), - a gas inlet port (5) and a gas outlet port (6), and - an ultraviolet radiation source (7) in the reaction internal space (4), said storage chamber being fluidly connected to the gas inlet port (5) and to the gas outlet port (6) of the reactor (1), the plant being characterised in that the ultraviolet radiation source (7) emits a radiation in the far-ultraviolet range whose spectral domain is comprised between 160 nm and 180 nm and has a variable power, in particular from 10 W to 500 W; and in that the gas inlet port (5) comprises a portion formed by a cylindrical duct a generatrix of which is tangent to a cross-section of the side wall (2) and enables a tangential inlet of the gaseous atmosphere into the reaction internal space (4) to create a turbulent flow characterised by a Reynolds number higher than 5,000 and by a non-zero vortical intensity of the gaseous atmosphere in the reaction internal space (4) for a flow rate of the gaseous atmosphere in the reaction internal space (4) of the reactor (1) from 60 m3 / h to 150 m3 / h; said process comprising at least one cycle comprising the following steps of: a) drawing the gaseous atmosphere from the closed enclosure, a1) introducing the gaseous atmosphere containing ethylene into the reaction internal space (4) of the reactor (1) via the gas inlet port (5) with a flow rate of the gaseous atmosphere in the reaction internal space (4) of the reactor (1) from 60 m3 / h to 150 m3 / h so as to create the turbulent flow characterised by a Reynolds number higher than 5,000 and by a non-zero vortical intensity of the gaseous atmosphere in the reaction internal space (4) of the reactor (1), b) treating the gaseous atmosphere to obtain a treated gaseous atmosphere, b1) extracting the treated gaseous atmosphere via the gas outlet port (6), c) introducing the treated gaseous atmosphere into the closed enclosure, characterised in that the treatment step b) is a step of petrochemically degrading ethylene carried out by the ultraviolet radiation source and wherein the stay time in the reaction internal space (4) of the reactor (1) is from 0.05 s to 60 s, in particular from 0.10 s to 25 s, most particularly from 0.15 s to 0.35 s.

2. The process according to claim 1, wherein the side wall (2) has a straight cylindrical shape.

3. The process according to claim 2, wherein the distance according to a transverse axis of the reactor (1), so-called air gap, between the ultraviolet radiation source (7) and the side wall (2) is from 1 mm to 499 mm, in particular from 10 mm to 250 mm, more particularly from 20 mm to 100 mm, most particularly 39 mm.

4. The process according to any one of claims 1 to 3, further comprising a programmer adapted to vary the power of the ultraviolet radiation source (7).

5. The process according to any one of claims 1 to 4, comprising n ultraviolet radiation sources (7) positioned according to the axis of revolution (Ox) of the reactor (1), n being an integer greater than or equal to 2.

6. The process according to any one of claims 1 to 5, comprising m ultraviolet radiation sources (7) in a plane (O, y, z) orthogonal to the axis of revolution (Ox), m being an integer greater than or equal to 2.

7. The process according to any one of claims 1 to 6, wherein the concentration of ethylene in the treated gaseous atmosphere is lower than 5 ppm, in particular lower than 2 ppm, more particularly lower than 1 ppm, and even more particularly lower than 0.03 ppm.