WO2009112408A1

WO2009112408A1 - Method for disinfecting a ventilation network and device for same

Info

Publication number: WO2009112408A1
Application number: PCT/EP2009/052553
Authority: WO
Inventors: Marie-Pierre Jaffrezic; Nelsie Berthelot
Original assignee: Dalkia France
Priority date: 2008-03-04
Filing date: 2009-03-04
Publication date: 2009-09-17
Also published as: FR2928272A1

Abstract

The invention relates to a method for disinfecting the inner walls of a ventilation network (104) without using any chemical other than ozone. The invention is characterised in that the method comprises: the step of generating a biocidal ionised gas essentially comprising ozone; the step of injecting the biocidal ionised gas into said network; and the step of condensing the biocidal ionised gas on the inner walls of the network; the device includes a generator (65, 102) for generating a biocidal ionised gas substantially comprising ozone, characterised in that the device further comprises a means (106) for injecting the biocidal ionised gas into the ventilation network.

Description

Method of disinfecting a ventilation network and its device

The present invention relates to the field of cleaning ventilation networks. It relates more specifically to a method and a device for disinfecting the internal walls of a ventilation network, such as but not exclusively the ventilation networks that are found in industrial or tertiary buildings, such as for example a network of air conditioning.

Such ventilation networks are well known elsewhere. They generally comprise a plurality of pipes connecting components of the ventilation network, such as fans, filters, cold and hot batteries, the air handling unit, or any other element.

The accumulation of dust or micro-organisms, especially in the ventilation network ducts, leads to a decrease in the energy performance of the network as well as a significant deterioration of the air quality inside the buildings.

Traditionally, the ventilation networks as described in FR 2,616,689, are maintained in the following manner: a brushing cleaning of the internal walls is associated with an aspiration of the dust; then, the network is disinfected by the misting of a chemical disinfectant. Disinfection should always take place after the cleaning step because otherwise this one is totally ineffective.

In addition, the components of the network other than pipes are cleaned manually.

Also known is WO 93/22603 which combines the use of a disinfectant chemical (a quaternary ammonium) with ionization.

It has been found that the spraying of liquid chemicals does not make it possible to obtain a homogeneous treatment, so that a good level of efficiency can not be achieved on all the walls of the ventilation network.

In addition, chemical disinfection requires the storage and handling of toxic chemicals in the building. Finally, the residual toxicity of the chemicals usually used is poorly evaluated. Nor is the time required to return to unpolluted air. In other words, there is a risk that during the restarting of the ventilation network, after the disinfection step, the pulsed air still contains chemical species of the disinfectant product.

An object of the present invention is to provide a method of disinfecting the internal walls of a ventilation network that overcomes the disadvantages of traditional methods described above. The invention achieves its object by the fact that the method according to the invention does not use disinfectant chemical other than ozone and comprises:

a step of generating a biocidal ionized gas containing essentially ozone; a step of injecting the biocidal ionized gas into said network; and

a step of condensation of the biocidal ionized gas on the internal walls of the network.

It is therefore understood that for the purposes of the present invention, the disinfection method uses only a biocidal ionized gas but no other chemical disinfectant quaternary ammonium type or otherwise.

For the purposes of the present invention, the internal wall of the network is understood to mean the partitions and / or internal faces of both the pipes and the components of the network which are brought into contact with the air circulating in the ventilation network. . Thus, for example, any inner face of the air handling unit which is in contact with the air of the network circulating therein will be described as an internal wall.

Condensation of the gas on the internal walls advantageously allows a homogeneous biocidal action in the pipes and especially in the components of the ventilation network.

It is understood that the biocidal ionized gas has an action on the internal walls of the ventilation network and not on the air circulating in the network. As a result, unlike traditional methods, the present method does not pollute the air in the network. Another advantage of the present invention is that the biocidal chemical species are generated at the time of disinfection. There is therefore no storage of disinfectant chemicals.

Furthermore, the inventor has found that the kinetics of abatement of samples containing bacterial spores such as those found in the ventilation networks is much greater in the case of the use of the present method than in the case of the use of vaporized chemicals.

Preferably, the biocidal ionized gas is selected to have a sporicidal property. More generally, it is arranged that the biocidal ionized gas contain oxidizing and acidifying gaseous species.

Preferably, the biocidal ionized gas contains ozone.

Of interest is that this ionized gas has a short life, especially on metal surfaces, such as those usually found in ventilation networks, whereby the downtime of the network is reduced.

Advantageously, the biocidal ionized gas is generated from a previously humidified gas mixture. This pre-humidification promotes condensation on the internal walls of the ventilation network. Still more preferably, the gaseous mixture has a relative humidity of greater than 80%.

The biocidal ionized gas is preferably generated from the ambient air, which may be optionally previously moistened if, given the ambient temperature, its hygrometry is insufficient to obtain the desired condensation.

According to a first embodiment of the method, the disinfection is carried out in situ in the ventilation network.

According to a second embodiment of the method according to the invention, the latter further comprises a step of isolating a pipe portion of the ventilation network, the pipe portion having first and second openings; the injection step of the biocidal ionized gas is carried out by injecting said gas into the pipe portion through its first opening; and a step of suction of the air contained in the pipe portion from its second opening is furthermore carried out. This second embodiment makes it possible, in particular, to perform piecewise disinfection of the ventilation network.

There may also be an additional step of catalytic reduction of the sucked air so as to remove the biocidal ionized gas.

The present invention also relates to a device for disinfecting a ventilation network that comprises a biocidal ionized gas generator and means for injecting the biocidal ionized gas into the ventilation network so that the biocidal ionized gas condenses on internal walls. ventilation network.

Advantageously, the device further comprises a gaseous mixture source, means for humidifying the gaseous mixture prior to its introduction into the generator so as to generate the biocidal ionized gas. Preferably, the gaseous mixture has a humidity level greater than 80%.

Advantageously, the generator comprises a high-voltage electrode surrounded by a ground-mass electrode. By a high voltage electrical discharge between these two electrodes, the gas in the generator is ionized.

According to an advantageous embodiment of the disinfection device of a ventilation network according to the invention, the latter further comprises a first nozzle for the injection of biocidal ionized gas into a portion of said network pipe by a first opening of said pipe portion, and a second nozzle for connection to a second opening of the pipe portion, and suction means connected to the second nozzle for sucking air contained in the pipe portion.

With this, it is possible to perform a specific disinfection of the ventilation network by disinfecting successively, step by step, a plurality of portions of pipe.

Preferably, the suction means are equipped with a catalyst.

The invention further relates to a ventilation network which comprises at least one disinfection device according to the invention. Such a network is including but not exclusively intended to be mounted in a building to ventilate a room.

Advantageously, the biocidal ionized gas generator is disposed in a pipe of the ventilation network. Still advantageously, the generator of biocidal ionized gas is fixed on an internal wall of the ventilation network, so that a generation of biocidal ionized gas in situ is carried out.

Advantageously, the ventilation network further comprises at least one ionized gas sensor which is preferably an ozone sensor. An interest is to be able to detect an exceeding of a predetermined limit value of biocidal ionized gas concentration. An alarm can be advantageously associated with such a sensor.

The invention will be better understood and its advantages will appear better on reading the following description of embodiments given by way of non-limiting examples. The description refers to the accompanying drawings in which:

FIG. 1 represents a ventilation network according to the present invention equipped with a plurality of disinfecting devices;

- Figure 2 shows a ventilation device according to the invention attached to an inner wall of the ventilation network of Figure 1; and

FIG. 3 schematizes an operation for disinfecting a portion of a duct of a ventilation network with the aid of a disinfection device according to another embodiment of the invention.

With the help of Figures 1 and 2, we will first describe a ventilation network according to the present invention.

The ventilation network 10 schematized here by way of non-limiting example, is of the recirculated air type, this type of network is well known elsewhere.

More specifically, the ventilation network 10 is intended to be installed in a building (not shown here), such as an industrial building, office or any other type of building that is desired to ventilate.

This building comprises at least one room 14, for example an office or a dwelling, ventilated through the ventilation network 10. The latter comprises a first air circuit 16 for drawing air "Nine" (that is to say, sucked outside the building) in the room 14, this circuit 16 can also draw air taken from the local 14, or a mixture of "new" air and of reclaimed air.

Considered from a "new" air inlet 18, the first air circuit 16 successively comprises several elements constituting the network, namely an adjustment flap 20, a mixing chamber 22 for mixing fresh air and air. return air, a filter 24, a hot battery 26, a cold battery 28, a fan 30, a filter 32, a sound trap 34 and finally an inlet 36 of the room 14 through which the air conditioning is drawn from inside from local 14.

As seen in Figure 1, the ventilation network 10 further comprises a second air circuit 38 extending between the room 14 and a discharge mouth 40 for the expulsion of the exhaust air outside the network of ventilation 10. Considered from the room 14, the second air circuit 38 comprises successively, a filter 42, a sound trap 44, a fan 46, a mixing box 48 connected to the outlet 40.

In the example shown here, the ventilation network 10 further comprises a third air circuit 50 connecting the second air circuit 38 to the first air circuit 16 through the mixing chambers 48,22.

The third air circuit 50, which comprises in this case an adjusting flap 52 for regulating the air flow, makes it possible to recycle a fraction of the air leaving the space 14 by re-injecting it into the first circuit of the air. air 16.

For the most part, the constituent elements of the network 10 are connected to each other via conduits 35, while some of these elements can be juxtaposed.

The arrows on the pipes 35 specify the direction of flow of the air in the ventilation network 10.

According to the present invention, the ventilation network 10 comprises a plurality of disinfection devices 12.

In the example shown here, there are seven disinfection devices 12, but it can obviously provide a different number.

The disinfecting devices 12 are preferably arranged in areas of the network 10 where the microbial growth is favored by stagnation of water or particles. Preferably, these disinfection devices 12 are arranged on the inner faces of the pipes 35 so as to be in contact with the air circulating in the network 10.

Each of these disinfection devices 12 is intended to generate a biocidal ionized gas intended to eliminate the microbial agents that develop on the internal walls of the network 10.

To do this, the biocidal ionized gas is condensed on the inner walls 60 of the network disposed near the disinfection device 12. The biocidal ionized gas thus acts in a liquid phase which increases its ability to destroy microbes.

Condensation can also be promoted by lowering the temperature of the internal walls of the network locally, for example by precirculating a flow of cold air into the ventilation network 10. Also, the condensation can be promoted by humidifying the air flowing through the ventilation network.

The generation of biocidal ionized gas may possibly take place when the network 10 is operating, so that the biocidal ionized gas is transported by the air stream.

According to the invention, the biocidal ionized gas essentially contains ozone. In addition, unlike the prior art, no additional chemical disinfectant is used.

To ensure the safety of the people in the room 14, an ozone sensor 33 is disposed in the pipe 35 which is upstream of the room 14. This advantageously allows the regulation of the ozone concentration generated, especially in case of exceeding of a predetermined limit value, for example the average value of exposure to ozone which is 200 μg / m ³ or the value fixed by the European Directive 2002/3 / EC ie 120 μg / m ³ in eight-hour average, or any other similar standard.

With the help of Figure 2, we will now describe in more detail one of the disinfection devices 12.

Preferably, this disinfection device 12 comprises a biocidal ionized gas generator 65 which is fixed on one of the internal walls 60 of the ventilation network, which inner wall 60 belongs in this case to one of the pipes 35. As can be seen in FIG. 2, the generator 65 is in the general form of an elongated tube mounted on the inner wall 60 via insulating connection supports 62, 64. Preferably, but not necessarily, the generator 65 extends transversely with respect to the flow direction of the air in the ventilation network 10.

More specifically, the biocidal ionized gas generator 65 comprises a high voltage electrode 66 forming a rod, as well as a ground electrode 68 forming a cylindrical sleeve which surrounds the high voltage electrode 66. In the example represented here, the high electrode voltage 66 consists of a threaded rod 70 promoting priming with the ground electrode 68, while the latter has a peripheral surface screened so as to allow the circulation of air in the space defined between the electrode high voltage 66 and the ground electrode 68. Moreover, the high voltage electrode 66 is fixed at its ends to the insulating connection supports 62, 64 while being electrically connected to a high voltage supply 69 disposed outside. ventilation network 10.

The generator of biocidal ionized gas 65 is in this case intended to generate ozone during an electric discharge caused between its two electrodes.

Thus, in this embodiment, the ozone is generated from the air contained in the ventilation network 10.

According to one variant, moist air is circulated in the ventilation network in order to improve the condensation of ozone on the internal walls 60 of the ventilation network 10.

With the help of Figure 3, we will now describe another embodiment of the invention.

While the first embodiment allows an in situ disinfection of the ventilation network, this other embodiment of the invention allows for it to perform a localized and localized disinfection of the ventilation network.

In this embodiment, the disinfection device 100 comprises a biocidal ionized gas generator 102 disposed outside the ventilation network 104, as well as means 106 for injecting the biocidal ionized gas into the ventilation network 104. species, these means 106 are in the form of a pipe 108 whose distal end 110 is introduced into a duct 112 of the ventilation network 104, for example by means of a inspection hatch 114, while its other end is connected The disinfecting device 100 further comprises a compressor 116, constituting a gas mixture source, which is here advantageously connected to means for humidifying the gaseous mixture, in this case a humidifier 118. Wet gas mixture, which preferably has a relative humidity of greater than 80% to promote condensation, is then introduced into the biocidal ionized gas generator 102, so as to generate a wet biocidal ionized gas. In this case, the biocidal ionized gas generated contains essentially ozone.

Preferably, the biocidal ionized gas generator 102 comprises one or more pairs of electrodes such as those described above and shown in FIG. 2. They are also powered by a high-voltage power supply 119.

We will now describe in more detail the disinfection process implemented by this disinfection device. According to this method, a step of isolating a pipe portion 120 of the ventilation network 104 is carried out.

To do this, the line 112 is closed at two remote points 122, 124 delimiting the pipe portion 120 to be disinfected.

For example, a closed register 126 may be placed at a distance from the inspection hatch 114 through which the distal end 110 of the tube 106 forming the first nozzle is introduced, and another closed register 128 remote from another inspection hatch 130 , so that the two inspection hatches 114,130 are arranged between the two registers.

A step of injecting the biocidal ionized gas into the pipe portion 120 thus isolated is then carried out by injecting the gas into the pipe portion through the hatch 114 constituting a first opening of the pipe portion 120.

The generated ozone condenses on the inner walls 121 of the pipe portion 120 and acts to destroy the microbial agents. Advantageously, a suction step of the air contained in the pipe portion 120 is also performed simultaneously from the hatch 130 constituting a second opening of the pipe portion 120. As can be seen in FIG. aspiration step is carried out by means of suction means 132 of the disinfection device 100, which comprise a casing 134 whose distal end, forming second nozzle 136, is introduced into the pipe portion 120 by the second opening 130 ( trap). Preferably, the suction means 132 comprise a fan 133 and are further equipped with a catalyst 138 promoting the decomposition of ozone into oxygen.

Advantageously, the disinfection device further comprises an ozone sensor 140 placed outside of the pipe portion 120 insulated so as to detect an exceeding of a predetermined limit value, such as for example the average value of Ozone exposure of 200μg / m ³ , For example, a dosimeter is placed on the operator to ensure that the operator is not exposed to an ozone concentration greater than the Mean Exposure Value . Once disinfected pipe portion 120, the disinfection process is restarted in an adjacent pipe portion, whereby it is advantageously disinfected, step by step, the entire ventilation network 104.

Claims

REVENDICATONS

A method of disinfecting the inner walls of a ventilation network (10, 104) without the use of a disinfectant chemical other than ozone, said method being characterized in that it comprises:

a step of generating a biocidal ionized gas essentially comprising ozone; a step of injecting the biocidal ionized gas into said network; and

2. Disinfection method according to claim 1, wherein the biocidal ionized gas is generated from a gaseous mixture previously moistened.

3. A disinfection method according to claim 2, wherein the gaseous mixture has a relative humidity greater than

80%.

4. Disinfection method according to any one of claims 1 to 3, wherein the biocidal ionized gas is generated from the ambient air.

5. Disinfection method according to any one of claims 1 to 4, wherein is further carried out a step of isolating a pipe portion (120) of the ventilation network (104), the pipe portion having first and second openings (114, 130); the injection step of the biocidal ionized gas is carried out by injecting said gas into the pipe portion through its first opening; and a step of suction of the air contained in the pipe portion from its second opening is furthermore carried out.

6. Device for disinfecting a ventilation network without the use of a chemical disinfectant other than ozone, characterized in that it comprises a generator of biocidal ionized gas (65, 102) consisting essentially of ozone and that it further comprises means (106) for injecting the biocidal ionised gas into the ventilation network.

7. Device for disinfecting a ventilation network according to claim 6, characterized in that it further comprises a gaseous mixture source (116), means (118) for moistening the gaseous mixture prior to its introduction into the atmosphere. generator so as to generate the biocidal ionized gas.

8. Device for disinfecting a ventilation network according to claim 7, characterized in that the gas mixture has a relative humidity of greater than 80%.

9. Disinfection device according to any one of claims 6 to 8, characterized in that the generator comprises a high voltage electrode (66) surrounded by a ground electrode grid

(68).

10. Device for disinfecting a ventilation network according to any one of claims 6 to 9, characterized in that it further comprises a first nozzle (110) for the injection of biocidal ionized gas in a driving portion. (120) of said network by a first opening (114) of said pipe portion, and a second nozzle (136) for connection to a second opening (130) of the pipe portion (120), and means suction nozzle (132) connected to the second nozzle for sucking air contained in the pipe portion.

11. Disinfection device according to claim 10, characterized in that the suction means are equipped with a catalyst (138).

12. Ventilation network (10, 104), characterized in that it comprises at least one disinfection device (12, 100) according to any one of claims 6 to 11.

13. Ventilation network according to claim 12, characterized in that the generator of biocidal ionized gas (65) is fixed on an inner wall (60) of the ventilation network.

14. Ventilation network according to claim 12 or 13, characterized in that the generator of biocidal ionized gas (65) is disposed in a pipe of the ventilation network.

15. Ventilation network according to any one of claims 12 to 14, characterized in that the generator (65) comprises a high voltage electrode surrounded by a ground electrode grid.

16. A ventilation network according to any one of claims 12 to 15, characterized in that it further comprises an ionized gas sensor (140, 33), including an ozone sensor.