METHOD FOR STERILIZING GAS FILTERING COMPONENTS, IN PARTICULAR AIR BUBBLES

Description

[0001] The present invention relates to a method for sterilizing gas filtration means, in particular blowing air.

[0002] The present invention relates more particularly to a method for sterilizing gas filtration means for the sterilization of gas filtration means according to said sterilization method.

[0003] We know of the state of the art for many types of gas filtration methods and especially for air filtration.

[0004] Such means of gas filtration are notably used for the filtration of blowing air in thermoplastic container manufacturing facilities, the manufacture of thermoplastic containers being achieved by blowing (or stretch-blowing) hot preforms into a mold using at least one fluid under pressure.

[0005] Containers, such as bottles, flasks or jars, are generally obtained from preforms which are first manufactured by injection molding of thermoplastic material, such as PET (Polyethylene Terephthalate), and which are subsequently heat-conditioned to obtain hot preforms suitable for molding.

[0006] To achieve this, an installation includes at least one oven for the heat conditioning of the preforms, coupled with a molding machine (or "blow molder") for molding the containers from the hot preforms. The installation also advantageously includes a sterilization unit to sterilize at least the inside of the preforms in order to obtain "sterile" containers.

[0007] To carry out blow molding or stretch-blowing of a hot preform, it is known to use at least one fluid for blowing, generally a gas, such as compressed air at pressures that can reach values ​​of 30 or 40 bars depending on the application.

[0008] The air used for blowing is introduced through the opening (the neck) of the hot preform placed in a mold so that the blowing air comes directly into contact with the internal surface of the container.

[0009] However, the internal surface is itself intended to come into contact with the contents of the container at a later date.

[0010] The quality of the blown air, more specifically the absence of contaminants such as microorganisms, particles like dust, etc., is therefore an important parameter to consider in order to guarantee, in the case of agri-food packaging, good preservation of the packaged product, including shelf life, and consumer safety.

[0011] However, the quality of the compressed air used for blowing is determined by a set of factors, from the quality of the intake air, which varies according to the environment of the industrial site and its location relative to polluting sources, to the condition of the distribution network and / or the installation.

[0012] Atmospheric air drawn in and compressed by at least one compressor, for example, has a higher or lower degree of humidity, and humidity promotes corrosion and the development of microorganisms.

[0013] Particular attention is also paid to the choice of compressors which, due in particular to the design of their lubrication systems, are likely to cause chemical contamination of the air, for example by lubricating oil or Teflon dust.

[0014] This is why the compressed air intended for use in blowing is pre-treated and especially filtered by gas filtration means in order to obtain blowing air that is "sterile", that is to say, in particular free of microorganisms.

[0015] The compressed air used for blowing is generally successively filtered by a filtration system comprising different means of gas filtration.

[0016] By way of non-limitation, such an air filtration system for blowing includes, for example, multiple filtration means which, arranged in series, are intended to deliver sterile air at the outlet.

[0017] For example, the air is successively filtered by first means of filtration of type "FFP" to obtain in particular oil removal, water purification and dust removal, then by second means of filtration of type "AK" (with activated carbon) to remove all oil vapors and gaseous hydrocarbons which can also cause an olfactory and gustatory nuisance, and finally by third means of filtration of type "SRF" to retain microorganisms.

[0018] Indeed, the blowing air is likely to be a vector of contamination of the inside of the preform, and therefore of the container, by introducing contaminants and especially microorganisms (viruses, germs, spores, etc.).

[0019] Control of the quality of the compressed air used for blowing is even more important when, in the container manufacturing process, the filling of the containers is carried out in an aseptic environment directly after the molding of the container obtained by blowing or stretch-blowing of a hot preform.

[0020] Indeed, in such a manufacturing process, sterilization is generally carried out upstream on the preforms, before their transformation into containers, so it is then essential to prevent the risks of contamination of the sterilized preforms, as well as that of the containers made from these preforms.

[0021] The invention aims to sterilize gas filtration means, including but not limited to blow-air filtration means, such as, for example, "SRF" type filtration means which are used to remove microorganisms from compressed air intended for blowing in the manufacture of sterile containers.

[0022] We are looking for solutions to sterilize such gas filtration devices, both before first use and after a certain amount of use.

[0023] Sterilization of filtration means must make it possible to destroy the microorganisms present, resulting in particular from the use of said filtration means, in order to prevent their development in the filtration means and thus eliminate the risks of migration of such microorganisms downstream of said filtration means during use.

[0024] In the case of an industrial application such as the manufacture of containers for the packaging of agri-food products, it is important to be able to guarantee quality and especially the sterility of the blown air filtered by means of such gas filtration.

[0025] With such sterilization, the aim is, for economic reasons, to also reduce the frequency of changing the filtration media.

[0026] To sterilize gas filtration means (or filters), it is known from the prior art to use steam, in particular to sterilize filters intended to filter air at low pressure.

[0027] Such steam sterilization has also been used to sterilize gas filtration means intended for blow-air filtration, such as filters designed to operate at high pressures like the aforementioned FFP type filters.

[0028] Sterilization is then generally carried out with food-grade steam, that is to say, steam characterized by a very low water content and the absence of impurities.

[0029] However, such steam sterilization of the filtration means used to filter the blowing air in a thermoplastic container manufacturing facility did not give satisfactory results for the reasons detailed below.

[0030] First, it was observed that the quality of the steam used during sterilization was inconsistent. Generally of insufficient quality, sometimes poor, the quality of the steam was particularly heterogeneous from one industrial site to another, even for the same container manufacturing facility.

[0031] Furthermore, even with high-quality steam, the sterilization of the filtration means obtained is not satisfactory.

[0032] Under these conditions and to preserve the quality of filtration, it is not uncommon to see an increase in the frequency of sterilization of filtration equipment, and also a significant reduction in its lifespan.

[0033] However, sterilizing the filtration means (as well as changing them) requires interrupting their use, which in our example of use means stopping the manufacture of containers, which is particularly economically damaging.

[0034] Studies have shown the presence of excess water in the filtration systems after such steam sterilization operations.

[0035] It was also established that temperatures induced by the use of steam, exceeding 120°C, caused damage to the filtration means and thereby degraded their filtration properties for subsequent use.

[0036] In addition to the lack of homogeneity in the quality of the steam used for sterilization, it was observed that an accumulation of water condensate occurred in the sterilized filtration means, with this condensate remaining trapped in the filtration means and proving particularly difficult to eliminate.

[0037] In steam sterilization, compressed air at ambient temperature is used to remove water in order to dry the filtration media. Such drying requires a significant amount of air when the flow rates used are, for example, on the order of 2000 to 3000 m³ / h.

[0038] The air pressure used for drying must not exceed certain pressure values, for example 4 bars, otherwise damage to the structure of the filtration means may occur.

[0039] Indeed, the presence of water in the filtration means opposes the passage of drying air through the filtration means and, by clogging them, the water modifies the pressure drop.

[0040] Finally, the drying air tends to forcefully push the condensates through the filtration means, even though the gas filtration means are hydrophobic.

[0041] Therefore, steam sterilization causes a degradation of the filtration means which can lead to their destruction, a destruction which is also completely unpredictable.

[0042] It follows from the above that the performance of the means of filtration of the blowing air thus sterilized with water vapor degrades and that their lifespan is considerably reduced.

[0043] Furthermore, imperfect removal of water condensate after steam sterilization of filtration media can prove particularly detrimental when their use is resumed.

[0044] Indeed, the water condensates still present in the filtration means (due to the excess water and the difficulty of its elimination) will then be pushed downstream by the gas such as the blowing air.

[0045] In the case of a container manufacturing installation, the high-pressure blowing air pushes water residues downstream of the filtration means, i.e. into the blowing circuit and then into the manufactured containers themselves, resulting in the blowing circuit being wetted and, above all, moisture being introduced inside the manufactured containers.

[0046] However, the presence of moisture inside the manufactured containers increases the risk of microbiological contamination.

[0047] Furthermore, there is another method for sterilizing filters besides the use of steam as described previously; this involves chemical sterilization, specifically the use of hydrogen peroxide to sterilize the filters.

[0048] Documents EP0815919, US2009 / 169421, and EP0243073 describe chemical sterilization by impregnating filters with hydrogen peroxide in either liquid or gaseous form and activating the hydrogen peroxide with hot air. Documents US 2012 / 020848 A1, EP 1 283 061 A1, and WO 93 / 17726 A1 are also known.

[0049] The aim of the present invention is in particular to resolve the aforementioned drawbacks and especially to propose a new solution for sterilizing gas filtration means, such as blow air filtration means used in a thermoplastic container manufacturing installation.

[0050] To this end, the invention proposes a method for sterilizing gas filtration means according to claim 1.

[0051] Advantageously, the sterilization process according to the invention makes it possible to effectively sterilize the gas filtration means, while preserving their integrity so as to maintain their filtration performance and increase their lifespan, or at least preserve it.

[0052] Indeed, the risks of degradation, or even destruction, of the structure of the filtration means are eliminated with chemical sterilization according to the invention.

[0053] Compared to steam sterilization, the invention does not require a large quantity of air because the hydrogen peroxide condensates are successively removed by heating with hot air.

[0054] The sterilization according to the invention is more economical in air with a hot air flow rate that is more than one hundred times lower than that of the air used for drying in the steam sterilization process or for evaporation of continuously injected hydrogen peroxide according to the prior art.

[0055] Advantageously, the sterilizing mixture comprises a determined dose of hydrogen peroxide in vapor form which is deposited by condensation on the filtration means when the gaseous mixture of hot air and vapor comes into contact with the filtration means.

[0056] Advantageously, the hydrogen peroxide condensates are then gradually removed by evaporation through heating with hot air, said evaporation being carried out at least between the injection of two successive doses of liquid hydrogen peroxide.

[0057] According to an important characteristic, it must be clearly understood that the sterilization process according to the invention is a process of a "chemical" nature.

[0058] Indeed, and in comparison with steam sterilization, the sterilizing effect does not result (or not solely) from the thermal destruction of microorganisms present in the filtration means, by the supply of heat due to steam.

[0059] In the invention, the hot air has a dual function: to thermally activate the hydrogen peroxide condensed on the filtration means and to eliminate at least a part of it by evaporation, depending on the duration of application of the hot air.

[0060] The hot air will first cause a gradual elimination by evaporation of the water present in the hydrogen peroxide condensates, which will have the effect of gradually increasing their concentration and therefore increasing their sterilizing effect.

[0061] In the case of a sterilizing agent formed by hydrogen peroxide (H2O2), thermal activation refers to the fact that hot air acts on the hydrogen peroxide to break its chemical bonds, which causes the appearance of active free radicals (OH) that will destroy microorganisms and allow the desired degree of sterilization to be obtained.

[0062] The sterilizing agent used for sterilizing the filtration means according to the invention is advantageously hydrogen peroxide (H2O2), known for its germicidal properties, particularly in the agri-food sector.

[0063] When hydrogen peroxide is also used in the container manufacturing installation to sterilize at least the inside of the thermoplastic preforms, the hydrogen peroxide supply source is likely, for example, to be a common source for the sterilization devices of the blow air filtration means, on the one hand, and of the preforms, on the other.

[0064] Advantageously, the sterilization process for the filtration means according to the invention comprises in turn, i.e. alternately, at least one step of applying the gaseous mixture comprising the hydrogen peroxide vapor obtained from said determined dose and a sterilization step using hot air.

[0065] The said application and sterilization steps constitute respectively a sequence which is advantageously repeated a number "n" of times to achieve a sterilization cycle, the evaporation of the hydrogen peroxide condensates being carried out at least in the given time interval between two successive injections of a determined dose of hydrogen peroxide.

[0066] After the repetition "n" times of said sequence, the sterilization process advantageously includes, at the end of the cycle, a complementary sterilization step consisting, as during said given time interval, of circulating only hot air through said filtration means to complete, if necessary, the elimination of hydrogen peroxide by evaporation.

[0067] The additional sterilization step is carried out for a duration which is determined in particular according to the value of said time interval, said step being able to be omitted when said time interval is sufficient to guarantee total evaporation of the hydrogen peroxide condensates deposited after the injection of each determined dose.

[0068] The sequential injection of hydrogen peroxide, that is to say the alternating repetition of the said steps of application of a fraction of the determined quantity of steam then of hot air for sterilization, advantageously makes it possible not to saturate the means of filtration, avoiding in particular any clogging.

[0069] Thanks to the sequential injection of a given dose of hydrogen peroxide, a smaller quantity of hydrogen peroxide is deposited which can then be totally or at least partially removed by the hot air during the said given time interval and this before proceeding to a new application resulting from the injection of a new given dose.

[0070] Advantageously, sequential injection reduces the amount of energy needed for sterilization and preserves filtration methods from degradation, particularly due to temperature effects.

[0071] The total amount of hot air (and therefore energy) required to evaporate all of the hydrogen peroxide is less when said hydrogen peroxide is applied discontinuously than if the amount corresponding to the sum of the doses were applied all at once.

[0072] Advantageously, the temperature of the hot air required to evaporate the equivalent of a given dose is also lower, so that this helps to preserve the filtration means from degradations such as those previously observed compared with water vapor.

[0073] After evaporation, hydrogen peroxide in its gaseous state is free to pass completely through the filtration means, to penetrate deep inside but without ever altering the structure as water vapor condensates did.

[0074] For an equal quantity of hydrogen peroxide vapor, the sterilization obtained from the filtration means is better by successively carrying out "n" times the sequence of said application and sterilization steps than by projecting an equivalent quantity of hydrogen peroxide vapor in a single pass.

[0075] According to other characteristics of the sterilization processThe process includes at least one vaporization step consisting of vaporizing said given dose of hydrogen peroxide in liquid form in evaporation means to obtain said gaseous mixture used in the application step; the process includes at least one injection step consisting of sequentially injecting said given dose of hydrogen peroxide in liquid form into a continuous flow of hot air with said given time interval between two successive injections and introducing the assembly into said evaporation means to obtain said gaseous mixture; the injection step of said given dose of hydrogen peroxide is carried out sequentially by selectively controlling means, respectively in the open position for a given period of time and in the closed position for a given time interval between two successive injections of said given dose of hydrogen peroxide in liquid form;The sterilization process consists of carrying out at least one cycle during which a sequence, comprising the said application and sterilization steps, is repeated a number "n" of times; the process includes at least one additional sterilization step consisting of circulating only hot air through the said filtration means for a duration which is determined according to the time interval to ensure evaporation of the hydrogen peroxide.

[0076] Other features and advantages will become apparent from the description that follows, for the understanding of which we will refer to the single figure which schematically represents an example of the realization of a sterilization device intended to be integrated into a container manufacturing installation to sterilize the means of gas filtration.

[0077] Figure shows a pneumatic diagram illustrating an example of the realization of a sterilization device 10 for sterilizing gas filtration means 12.

[0078] In the embodiment example, the said gas filtration means 12 consist of blowing air filtration means.

[0079] The filtration means 12 are intended to filter high-pressure compressed air to deliver sterile air suitable for use as a blowing fluid in an installation (not shown) for manufacturing thermoplastic containers from hot preforms.

[0080] The high-pressure compressed air used for blowing hot preforms into containers, hereinafter referred to as blowing air, must be "sterile" air, that is to say, free from contaminants and especially microorganisms.

[0081] The term "high pressure" generally refers to both the final pressure of the blowing air, which can reach 25 or 40 bars for certain applications, and a lower pressure intended for pre-blowing or also for blowing, and for example between 7 and 20 bars.

[0082] According to the invention, chemical sterilization of the air filtration means 12 is carried out using at least one sterilizing agent in vapor form which, after being deposited on said filtration means 12, is thermally activated and removed by evaporation using hot air produced by the sterilization device 10.

[0083] The sterilizing agent used for sterilizing the filtration means is hydrogen peroxide (H2O2).

[0084] In the embodiment illustrated in the figure, the filtration means 12 include at least one filter.

[0085] In an alternative not shown, the filtration means 12 include more than one filter to filter the air intended for blowing.

[0086] To deliver sterile air, the filtration means 12 are for example made up of at least one “SRF” type filter.

[0087] Preferably, the said filtration means 12 shown in the figure form the last filtration means of a multiple filtration system of the type described above and are in particular suitable for carrying out a final filtration of the air before its use for blowing.

[0088] Preferably, said multi-filtration system includes means for dehumidifying the air.

[0089] Such filtration methods are more specifically designed to eliminate microorganisms from the air and may, for this purpose, include more than one stage of filtration.

[0090] In an alternative configuration not shown, the filtration means 12 comprise at least two filtration stages, for example in series, to achieve double filtration. Regardless of the number of filtration stages, a filtration stage may also comprise more than one filtration means (or filter), for example two filters in parallel.

[0091] Figure 14 shows only part of a blowing circuit of a molding machine or "blower" (not shown).

[0092] As is known, such a molding machine is for example of the rotary type and is equipped with a plurality of stations for blow molding or stretch blow molding of thermoplastic containers from hot preforms.

[0093] The filtration means 12 are arranged in a main conduit 16. The conduit 16 is connected at one end, upstream of the filtration means 12, to a blowing air source 18 delivering said compressed air under pressure and whose maximum value is determined according to the applications.

[0094] Regulation means 20 are arranged in the conduit 16 between said source 18 of blowing air and the filtration means 12, in order to be able in particular to isolate said filtration means 12 during sterilization by means of said sterilization device 10.

[0095] In the open position, the control means 20 allow, from the upstream supply air source 18, an upstream to downstream flow of air in the duct 16 and, in the closed position, the control means 20 interrupt said air flow in the duct 16, between the supply air source 18 and the downstream filtration means 12.

[0096] The conduit 16 is connected at the other end, downstream of the filtration means 12, to at least one part 15 of the blowing circuit 14 through which the blowing air filtered by said filtration means 12 is conveyed to blowing means (not shown), such as at least one nozzle, associated with a mold of said container molding machine.

[0097] Regulation means 22 are arranged in the conduit 16 between said part 15 of the blowing circuit 14 and the filtration means 12, in particular to be able to isolate said filtration means 12 during sterilization and with respect to said part 15 of the blowing circuit 14.

[0098] Preferably, the control means 20 and 22 are formed by at least one valve such as a solenoid valve.

[0099] The regulating means 20 and 22 are selectively controlled by a control unit (not shown) between at least one open position and one closed position.

[0100] In the open position, the control means 22 allow air to flow from upstream to downstream in the duct 16 and, in the closed position, the control means 22 interrupt said air flow in the duct 16, between the filtration means 12 and the part 15 of the blowing circuit 14 located downstream.

[0101] Advantageously, the sterilization device 10 is selectively controlled between a standby state in which said sterilization device 10 is inactive and a use state in which the sterilization device 10 is active, used to sterilize the filtration means 12.

[0102] Preferably and according to the embodiment example, the sterilization device 10 is equipped with an installation for manufacturing containers made of thermoplastic material by blow molding or by stretch-blowing of hot preforms.

[0103] Advantageously, the sterilization device 10 can be fitted to a manufacturing facility, whether said facility is new or existing.

[0104] Alternatively, the sterilization device 10 constitutes an independent unit of the installation capable of sterilizing various means of gas filtration.

[0105] The sterilization device 10 is more particularly associated with the blowing machine (or blower) of such an installation to sterilize the means 12 of air filtration.

[0106] The device 10 for sterilizing air filtration means according to the invention is in particular capable of replacing a steam sterilization device according to the prior art and as described in the preamble.

[0107] Preferably, the sterilization device 10 is capable of sterilizing blow-air filtration means 12 in place, i.e. in the operating position that said filtration means 12 occupy when containers are manufactured by the installation and the inactive sterilization device 10 is in standby mode.

[0108] Advantageously, no intervention is required on the filtration means 12, in particular no human intervention to carry out disassembly and reassembly.

[0109] Sterilization can therefore be carried out automatically by ordering the sterilization device 10.

[0110] To achieve such sterilization of the means 12 for blowing air filtration using the sterilization device 10, the manufacture of containers must be interrupted beforehand.

[0111] Initially, the operating mode of the installation is changed from a container manufacturing mode in which containers are likely to be manufactured from hot preforms, to another operating mode, called an intervention mode, in which container manufacturing ceases.

[0112] Interventions such as the sterilization of the blowing air filtration means 12 using the sterilization device 10 are then likely to be carried out.

[0113] The change in the operating mode of the installation in order to carry out a sterilization of the means 12 of blowing air filtration is accompanied by a change of state of the sterilization device 10 which is activated, going from standby state to operating state.

[0114] The device 10 for sterilizing filtration means will be described below according to the embodiment illustrated in the figure and whose operation will be described in detail later.

[0115] In the embodiment illustrated in the figure, the sterilization device 10 includes at least a first circuit C1 mainly for air which is associated with a second circuit C2 for the sterilizing agent formed here by hydrogen peroxide (H2O2).

[0116] The sterilization device 10 is specifically intended for implementing the sterilization process for gas filtration means according to the invention.

[0117] The sterilization device 10 is in particular intended to be used for the sterilization of blow air filtration means in a manufacturing installation for thermoplastic containers from hot preforms.

[0118] The first circuit C1 of the sterilization device 10 includes at least one conduit 24, the upstream end of which is connected to a compressed air supply source 26.

[0119] Preferably, the compressed air supply source 26 is a compressed air distribution network delivering air at a predetermined pressure, for example a low pressure of about 7 bar.

[0120] Advantageously, the first circuit C1 includes means 28 for filtering the compressed air delivered by said supply source 26.

[0121] Preferably, the filtration means 28 allow the removal of contaminants present in the compressed air and are arranged in the pipe 24 at the inlet of the first circuit C1, at the upstream end connected to the supply source 26.

[0122] Advantageously, the first circuit C1 includes pressure regulation means 30 to regulate the pressure of the compressed air circulating in the pipe 24 to ensure a constant flow rate.

[0123] The 30 means of pressure regulation are for example made up of a pilot-operated diaphragm pressure regulator to regulate the dynamic pressure of the compressed air.

[0124] Preferably, the pressure regulation means 30 are arranged in the conduit 24, downstream of the compressed air filtration means 28.

[0125] Advantageously, the first circuit C1 includes means 32 for regulating the air circulation in the duct 24. Preferably, the regulating means 32 are formed by at least one valve such as a solenoid valve.

[0126] The control means 32 are arranged in the conduit 24, for example downstream of the pressure control means 30 and are controlled to selectively establish a flow of compressed air in the conduit 24.

[0127] The 32 regulating means are selectively controlled by a control unit (not shown) between at least one open position and one closed position.

[0128] Preferably, the sterilization device 10 includes a control unit to control, in particular, all the means of regulation.

[0129] In the open position, the control means 32 allow a flow of compressed air from upstream to downstream in the conduit 24 and, in the closed position, the control means 32 interrupt said flow of air in the conduit 24.

[0130] Preferably, the first circuit C1 includes pressure measuring means 34 arranged to measure the pressure of the compressed air flowing in said conduit 24.

[0131] Advantageously, the first circuit C1 includes heating means 36 for heating the compressed air selectively circulated in the pipe 24.

[0132] The pressure measurement means 34 are preferably arranged downstream of the regulation means 32 and upstream of the heating means 36.

[0133] The pressure measurement means 34 are for example formed by a pressure probe, allowing in particular monitoring of the dynamic pressure of the air circulating in the pipe 24 of the first circuit C1.

[0134] The heating means 36 include, for example, at least one air heater which is capable of heating the compressed air circulating in the pipe 24 to a given setpoint temperature (Tc).

[0135] The air heating means 36 are selectively controlled so that the temperature of the air circulating downstream is at least at said setpoint temperature (Tc).

[0136] Preferably, the given setpoint temperature (Tc) is a temperature of approximately 220°C. Such a setpoint temperature (Tc) value makes it possible to obtain hot air with a temperature of approximately 110°C when it comes into contact with the said filtration means 12.

[0137] Such a temperature of hot air, advantageously below 120°C, makes it possible not to damage the means 12 of filtration when the hot air comes into contact with them.

[0138] To selectively control the heating means 36 and control the hot air temperature, the circuit C1 of the sterilization device 10 includes temperature measurement means 38.

[0139] The temperature measurement means 38 are suitable for measuring the temperature of the hot air circulating in the duct 24 after passing through the heating means 36 formed by said at least one heater.

[0140] Preferably, the air temperature measurement means 38 are arranged downstream of said heating means 36.

[0141] The C1 circuit of the sterilization device 10 includes a purge line 40, one upstream end of which is connected to the line 24 and the other downstream end of which is connected to means 42 for evacuating out of the sterilization device 10.

[0142] The 42 means of evacuation are intended to collect the air, hot or not, in particular when the air temperature does not conform to the said setpoint temperature (Tc).

[0143] Preferably, the purge line 40 is connected to the line 24 downstream of the air heating means 36.

[0144] Regulation means 44 are arranged in the purge line 40 and are controlled to selectively establish an air circulation in the line 40, in bypass of the line 24.

[0145] Preferably, the 44 regulating means are formed by at least one solenoid valve.

[0146] The 44 regulating means are selectively controlled by said control unit (not shown) between at least one open position and one closed position.

[0147] In the open position, the control means 44 allow a flow of compressed air from upstream to downstream in the purge line 40 and, in the closed position, the control means 44 interrupt said air flow in the purge line 40.

[0148] The conduit 24 of the first circuit C1 has at another end, downstream i.e. opposite the source 26 of compressed air supply, at least one evaporator 46.

[0149] Preferably, a fitting 48 is interposed between the pipe 24 and an inlet of said at least one evaporator 46.

[0150] The fitting 48, for example an inverted "T" shape, has an internal main conduit into which hydrogen peroxide injection means 50 open.

[0151] Advantageously, the means 50 for injecting the sterilizing agent formed by hydrogen peroxide are suitable for spraying it in the form of a mist made up of very fine droplets.

[0152] A hydrogen peroxide injection line 52 from the second circuit C2 of the sterilization device 10 is connected to said injection means 50 opening into the conduit of the fitting 48 to inject, into the hot air passing through it, hydrogen peroxide in liquid form.

[0153] The evaporator 46 has a cavity 54 inside which are arranged at least 56 heating means for producing sterilizing agent vapor from the mixture of hot air from the line 24 of the first circuit C1 and liquid hydrogen peroxide from the injection line 52 of the second circuit C2.

[0154] Temperature measurement means 58 are associated with the evaporator 46 to measure the temperature of the mixture present inside the cavity 54 and consisting of hot air and hydrogen peroxide vapor, which is advantageously introduced sequentially in doses at the fitting 48.

[0155] The evaporator 46 is connected to the pipe 16 of the blowing circuit 14 by a pipe 60. One upstream end of the pipe 60 communicates with the cavity 54 of the evaporator 46 and the other downstream end of the pipe 60 connects to the pipe 16.

[0156] The 60 line of the sterilization device 10 connects to the 16 line between the regulating means 20 and the filtration means 12.

[0157] Regulation means 62 are arranged in the conduit 60 to selectively control the circulation in said conduit 60 of the gas mixture which, consisting of hot air and hydrogen peroxide vapor produced by the evaporator 46, is intended to be introduced into the blowing circuit 14 and more specifically into the conduit 16 for the sterilization of said filtration means 12.

[0158] Preferably, the control means 62 consist of at least one valve, such as a solenoid valve. The control means 62 are selectively controlled by the control unit (not shown) between at least one open position allowing the mixture to flow in the line 60 and a closed position interrupting the flow in the line 60.

[0159] The temperature measurement means 58 are used in particular to control at least the heating means 56 and / or the regulation means 62.

[0160] A discharge pipe 64 is provided to discharge effluents from the mixture after sterilization by the filtration means 12 to collection means 66, such as a sewer.

[0161] The evacuation pipe 64 has one end connected to the pipe 16 between the filtration means 12 and the regulation means 22, and another end which communicates downstream with said collection means 66.

[0162] Regulation means 68, such as a solenoid valve, are arranged in the discharge pipe 64 to control the flow in said pipe 64.

[0163] The regulating means 68 are selectively controlled by the control unit (not shown) between at least one open position allowing flow in the discharge conduit 64 and a closed position interrupting flow in said conduit 64.

[0164] Part of the mixture introduced into the pipe 16 via the pipe 60 is, after sterilizing the filtration means 12, discharged through the discharge pipe 64 to the collection means 66 when the regulating means 68 are in the open position.

[0165] Temperature measurement means 65 are arranged to measure the temperature in the discharge pipe 64.

[0166] Preferably, the means 65 for temperature measurement consist of a thermocouple.

[0167] Advantageously, the first 65 temperature measurement means allow for temperature monitoring during the sterilization of the 12 filtration means and for sending the measurement back to the control unit.

[0168] Preferably, treatment means 70 are interposed in the evacuation pipe 64, upstream of the collection means 66.

[0169] Such treatment means 70 include, for example, water and are specifically intended to treat hydrogen peroxide present in gaseous form in the effluents flowing in the discharge pipe 64.

[0170] Means 72 for measuring the concentration of hydrogen peroxide are advantageously associated with the means 70 for treatment in order to carry out a control, in particular before evacuation to the means 66 for collection.

[0171] The means 72 for measuring the concentration of hydrogen peroxide are advantageously used to check, at the end of the sterilization cycle, that the quantity of hydrogen peroxide measured is less than a threshold value meaning that all of the hydrogen peroxide has been evaporated.

[0172] The second circuit C2 of the sterilization device 10 is intended to deliver the hydrogen peroxide used to sterilize the filtration means 12.

[0173] The hydrogen peroxide injection line 52 connected, via the fitting 48 and the injection means 50, to the first hot air circuit C1 of the sterilization device 10 includes regulating means 74.

[0174] The regulating means 74, such as a solenoid valve, are arranged in the injection line 52 and are selectively controlled by the control unit (not shown) between at least one open position allowing flow in the line 52 and a closed position interrupting flow in the line 52.

[0175] The expression "determined quantity" of hydrogen peroxide refers to the quantity of hydrogen peroxide required to sterilize the filtration means for a sterilization cycle.

[0176] Furthermore, the expression "given dose" and "determined dose" should be understood as a fraction of the determined quantity of hydrogen peroxide required to carry out a filter sterilization cycle.

[0177] Therefore, the sum of the given doses corresponds to the determined quantity of hydrogen peroxide needed to carry out a sterilization cycle of the filtration medium.

[0178] The second circuit C2 includes at least one reservoir 76 with a specified capacity. The reservoir 76 is intended to be filled with a specified quantity of liquid hydrogen peroxide.

[0179] Preferably, the tank 76 is connected by a supply line 78 to a hydrogen peroxide supply source 80. The hydrogen peroxide has, for example, a concentration of around 25%.

[0180] Preferably, the pipe 78 has at least one valve 79 to be able to isolate the pipe 78 and therefore the second circuit C2 from the source 80 in order to allow in particular maintenance interventions.

[0181] Advantageously, the conduit 78 includes filtration means 82 to filter hydrogen peroxide upstream of the reservoir 76.

[0182] The second circuit C2 includes control means 84 which are arranged in the supply line 78 to control the flow of hydrogen peroxide in said line 78, between the source 80 and the reservoir 76.

[0183] Preferably, the regulating means 84 are arranged downstream of the filtration means 82 and upstream of the reservoir 76, more precisely upstream of the connection of the injection line 52 with the line 78.

[0184] The 84 regulating means are for example formed by a solenoid valve, such as a 2 / 2 type solenoid valve.

[0185] The regulating means 84 are selectively controlled by the control unit (not shown) between at least one open position allowing flow in the conduit 78 and a closed position interrupting flow in the conduit 78.

[0186] With the regulating means 84 in the open position (as well as the valve 79), the hydrogen peroxide in the liquid state flows from the source 80 to the reservoir 76, being advantageously filtered by the filtration means 82.

[0187] The reservoir 76 has a determined capacity corresponding, for example, to the quantity of hydrogen peroxide needed to carry out a sterilization cycle to sterilize the filtration means 12.

[0188] Of course, the capacity of the 76 tank can vary depending on the applications but could also be larger and not correspond to the quantity needed to carry out a single sterilization cycle.

[0189] The second circuit C2 includes level measurement means 86, 88, such as probes, to control the filling of the tank 76 or the purging.

[0190] The level measurement means include at least first means 86 for measuring a low level in the tank 76 and second means 88 for measuring a high level in the tank 76.

[0191] Advantageously, said measuring means 86 and 88 are connected to the control unit (not shown) to command in particular the closure of the regulating means 84 in order to interrupt the filling when the tank 76 contains the desired quantity of hydrogen peroxide.

[0192] Advantageously, the tank 76 is capable of being pressurized via a pipe 90, one end of which is connected upstream to the first compressed air circuit C1 and the other end downstream is connected to the tank 76.

[0193] Preferably, pipe 90 connects to pipe 24 of the first circuit C1 downstream of the pressure regulating means 30 and upstream of the regulating means 32.

[0194] 92 regulating means are arranged in the pipe 90 to control the pressurization of the tank 76.

[0195] The 92 means of regulation are for example constituted by a solenoid valve, such as a 3 / 2 type solenoid valve.

[0196] The regulating means 92 are selectively controlled by the control unit (not shown) between at least one open position allowing flow in the conduit 90 and a closed position interrupting flow in the conduit 90.

[0197] In the open position of the regulating means 92, compressed air from the first circuit C1 is admitted into the tank 76 so as to exert on the liquid hydrogen peroxide present in the tank 76 a pressure, for example of the order of 7 bars, i.e. a pressure greater than atmospheric pressure.

[0198] Pressurization ensures good flow of hydrogen peroxide out of tank 76, in particular towards injection line 52.

[0199] The 92 regulating means provide a venting function allowing for release to the open air, particularly when filling the reservoir 76 with sterilizing agent, the pressurization of the reservoir 76 being carried out after it has been filled.

[0200] Preferably, the second hydrogen peroxide circuit C2 includes pressure measurement means 94 associated with the tank 76 to measure in particular the pressure inside said tank 76 and its variations.

[0201] The 94 means of pressure measurement include, for example, at least one pressure sensor, connected to the control unit.

[0202] Advantageously, the pressure measurement means 94 make it possible to monitor the pressure variation to determine the quantity of hydrogen peroxide injected through the injection line 52.

[0203] The second circuit C2 of the sterilization device 10 includes a purge line 96, the upstream end of which is connected to the lower part of the reservoir 76 and the downstream end of which is connected to means 97 for evacuating out of the sterilization device 10.

[0204] The 97 evacuation means are intended to collect the sterilizing agent consisting of liquid hydrogen peroxide.

[0205] Preferably, the purge line 96 is connected to the lower part of the tank 76.

[0206] Regulation means 98 are arranged in the purge line 96 and are controlled to selectively establish a flow of hydrogen peroxide towards the discharge means 97.

[0207] Preferably, the control means 98 consist of at least one solenoid valve. The control means 98 are selectively controlled by said control unit (not shown) between at least one open position and one closed position.

[0208] In the open position, the regulating means 98 allow a flow of hydrogen peroxide in the purge line 96, from the reservoir 76 to the evacuation means 97.

[0209] In the closed position, the regulating means 98 interrupt the flow of hydrogen peroxide in the purge line 96.

[0210] The second circuit C2 includes a pipe 100 which is connected to the supply pipe 78, advantageously downstream of the filtration means 82.

[0211] Pipe 100 is intended to supply liquid hydrogen peroxide to at least one other sterilization device used in the container manufacturing facility comprising sterilization device 10.

[0212] Preferably, the line 100 includes at least one valve 101 to be able to interrupt the flow of hydrogen peroxide in the line 100.

[0213] Advantageously, said other sterilization device is that used to sterilize at least the inside of the preforms for the manufacture of thermoplastic containers.

[0214] We will now describe the use of the sterilization device 10 according to the embodiment example just described and more particularly the implementation of the sterilization process according to the invention by means of such a sterilization device 10.

[0215] As previously indicated, in order to sterilize the means 12 for filtering the blowing air, the installation or at least the molding machine (or "blower") is commanded to interrupt the manufacture of containers and change the mode of operation from the container manufacturing mode to the intervention mode.

[0216] The sterilization device 10 is also selectively controlled to switch from standby to operating state in order to sterilize the filtration means 12.

[0217] The sterilization device 10 is in standby mode when the installation is in container manufacturing mode.

[0218] The regulating means 20, 22 and 44 are then respectively in the open position and the other regulating means of the sterilization device 10 are in the closed position.

[0219] Preferably, the sterilization process for the filtration means 12 includes a preliminary phase which, beginning after the change of state of the sterilization device 10, consists of carrying out one or more preparatory steps before starting the sterilization of the filtration means 12.

[0220] The preliminary phase includes at least one step of isolating the 12 filtration means in order in particular to be able to sterilize them.

[0221] The isolation step allows the air filtration means 12 to be isolated from the air blowing circuit 14 located downstream of said filtration means 12.

[0222] Advantageously, sterilization is carried out "in-line" without dismantling the filtration means 12 and automatically thanks to the sterilization device 10.

[0223] The isolation step consists of controlling some of the means 20, 22, 44 of regulation of the sterilization device 10, when they consist of solenoid valves, from their open position to their closed position in order to isolate said means 12 of filtration.

[0224] In order to obtain, on the one hand, the hot air used in the sterilization process and, on the other hand, the hydrogen peroxide vapor, the air heating means 36 comprising at least said heater and the evaporator heating means 56 are respectively electrically powered, energized.

[0225] The compressed air delivered by source 26 is introduced into the first air circuit C1.

[0226] Advantageously, the air undergoes one or more treatment stages before being heated, in particular by the said means 36 of heating of the first air circuit C1.

[0227] The air is heated by the said heating means 36 during the preliminary phase until it reaches a desired temperature, but is also heated during the sterilization of the filtration means 12 according to the process.

[0228] Preferably, the process includes at least one air filtration step consisting of filtering the air delivered by the compressed air supply source 26.

[0229] In the sterilization device 10, the compressed air supplied by the supply source 26, such as a low-pressure compressed air distribution network delivering air at a pressure of around 7 bar, is filtered by the filtration means 28.

[0230] Preferably, the process includes at least one pressure regulation step consisting of regulating the pressure of the air delivered by said compressed air supply source 26 to obtain a determined pressure in the first circuit C1 from said source 26, so as to have a constant air flow.

[0231] Preferably, the said pressure regulation step is carried out after the compressed air filtration step using the pressure regulation means 30 of the first circuit C1 arranged downstream of the filtration means 28.

[0232] Advantageously, the process includes at least one step of measuring air pressure consisting of measuring the air pressure downstream of said pressure regulating means 30 in order to check that the air pressure is equal to said determined pressure.

[0233] Preferably, the preliminary phase of the process includes an air preheating step consisting of heating the air delivered by the compressed air supply source 26 until it reaches at least a determined setpoint temperature (Tc).

[0234] As previously stated, the air intended to be heated is advantageously pre-filtered and / or pressure-regulated.

[0235] The air preheating step also consists of heating the air contained in the cavity 54 of the evaporator 46 until it reaches at least a determined setpoint temperature (Tc).

[0236] The air temperature is advantageously measured by measuring means 38 and by measuring means 58 to determine whether said air temperature is at least equal to said determined setpoint temperature (Tc).

[0237] Preferably, the setpoint temperature (Tc) determined is identical for heating means 36 and heating means 56.

[0238] As a non-limiting example, the setpoint temperature (Tc) value is approximately 220°C.

[0239] The process includes at least one air temperature control step carried out at least during the preheating phase. Advantageously, this air temperature control step continues throughout the sterilization process.

[0240] The air temperature control step consists at least of measuring the temperature of the heated air to check that the air temperature is at least equal to said setpoint temperature (Tc).

[0241] In a sterilization device 10 according to the exemplary embodiment, said air temperature control step consists of measuring the air temperature through temperature measuring means 38 associated with heating means 36 and / or temperature measuring means 58 associated with said heating means 56 of said at least one evaporator 46.

[0242] During the preheating stage, the control means 32, 62 and 68 of the sterilization device 10 are in the open position and the control means 44 are in the closed position.

[0243] The process includes a step of circulating hot air in the first circuit C1 in particular to avoid condensation in the first circuit C1, upstream of the filtration means 12.

[0244] The hot air circulation step in the first circuit C1 allows the temperature setpoint values, in particular the said setpoint temperature (Tc), to be reached more quickly.

[0245] Preferably, a circulation of hot air with a temperature at least equal to said setpoint temperature (Tc) is maintained for a determined period, for example about ten minutes, through the first circuit C1 and the filtration means 12.

[0246] As previously indicated, the heating of the air continues after the preheating stage following a heating stage consisting of continuously heating, at the said setpoint temperature (Tc), the air intended to be used for sterilization.

[0247] The heating means 36 comprising said at least one heater are electrically powered to obtain said hot air and said heating means 56 comprising said at least one evaporator 46 are also powered to obtain hydrogen peroxide vapor.

[0248] The preliminary phase of the sterilization process also includes steps for preparing the second C2 circuit of hydrogen peroxide (H2O2).

[0249] Preferably, the preliminary phase includes at least one draining step consisting of purging all or part of the second circuit C2 and in particular the reservoir 76.

[0250] The emptying step consists at least of ordering the opening of the regulating means 92 and 98 to purge the tank 76.

[0251] The opening of the regulating means 98 allows the circulation of hydrogen peroxide through the purge line 96, from the reservoir 76 to the evacuation means 97.

[0252] The opening of the regulating means 92 allows the tank 76 to be vented to the open air (at atmospheric pressure), the hydrogen peroxide possibly present in the second circuit C2 and particularly in the bottom of the tank 76 is then likely to be evacuated through the purge line 96.

[0253] Preferably, the emptying step is interrupted after a determined time, for example a time of at least five seconds after the absence of measurement (or loss of information) by the low level measuring means 86 which, associated with the tank 76, are connected to the control unit.

[0254] The emptying step includes, in addition to purging the tank 76, purging the hydrogen peroxide supply line 78 of the second circuit C2.

[0255] The control means 84 are controlled in the open position to allow the flow of hydrogen peroxide present in the supply line 78 to the reservoir 76, then the control means 98 are also in the open position to the discharge means 97.

[0256] The regulating means 92 and 98 are maintained in the open position during the purging of the supply line 78.

[0257] Advantageously, the hydrogen peroxide present in the second circuit C2 is completely purged by the draining step in order to ensure that the properties of the sterilizing agent are not altered.

[0258] Once the draining step has been completed, the reservoir 76 of the second circuit C2 is filled with "fresh" hydrogen peroxide so that the second circuit C2 is operational to deliver said hydrogen peroxide in liquid form.

[0259] The filling stage as well as the emptying stage are implemented during the said preliminary phase to the sterilization of the filtration means 12.

[0260] The process includes a filling step consisting of filling said at least one reservoir 76 with a sterilizing agent consisting of liquid hydrogen peroxide.

[0261] The reservoir 76 constitutes a means of storing hydrogen peroxide whose capacity preferably allows the storage of a determined quantity corresponding to the quantity necessary to carry out a sterilization cycle of the filtration means 12.

[0262] To proceed with filling, the closing of the regulating means 98 arranged in the purge line 96 is commanded.

[0263] In the example of the implementation of the sterilization device 10, the control unit controls the solenoid valve constituting the means 98 of regulating their open position to their closed position.

[0264] The filling of the tank 76 is carried out from the hydrogen peroxide supply source 80 through the supply line 78.

[0265] During filling, the regulating means 84 and 92 are in the open position and the regulating means 74 are in the closed position.

[0266] Filling continues until the high level measuring means 88, associated with the tank 76, detect hydrogen peroxide.

[0267] At the end of the filling step, the reservoir 76 contains at least the determined quantity of liquid hydrogen peroxide to sterilize said filtration means 12 according to the process.

[0268] The preliminary phase is then completed and the actual sterilization phase of the filtration means 12 can begin.

[0269] The sterilization process for gas filtration means 12 comprises at least: a preliminary phase comprising: an isolation step of the filtration means 12, in particular from the air blowing circuit located downstream of said filtration means to be sterilized; a preheating step of the air used in the sterilization process consisting of heating the air delivered by the compressed air supply source until it reaches at least a determined setpoint temperature Tc; When the preliminary phase is completed then a sterilization phase can begin;The sterilization phase comprises: an application step consisting of circulating through the gas filtration means 12 a gaseous mixture comprising hot air and a determined quantity of hydrogen peroxide vapor, in which said determined quantity of hydrogen peroxide vapor is obtained by sequentially injecting, with a given time interval (t) between two successive injections, a given dose of hydrogen peroxide in liquid form into the hot air; and a sterilization step consisting, during said time interval (t), of maintaining the circulation of hot air through said filtration means to remove by evaporation all or part of the hydrogen peroxide deposited on said filtration means during said application step. In this filtration media sterilization process, the same hot air is used in the application step as in the sterilization step.

[0270] In other words, after carrying out the preliminary phase for the implementation of the filter sterilization process, said process includes a continuous application of a hot air stream through at least one filter to be sterilized, a step of injecting a given dose of hydrogen peroxide into the hot air stream to apply the hydrogen peroxide to the filter, this application step is followed by a sterilization step consisting of allowing time for the hot air stream to evaporate the hydrogen peroxide injected during the previous step and present at the level of the filter, these two steps are repeated as many times as necessary for the determined quantity of hydrogen peroxide to be reached for carrying out the sterilization cycle of the filtration means.

[0271] The sterilization process for gas filtration means 12 comprises at least: an application step consisting of circulating, through the gas filtration means 12, a gas mixture comprising hot air and a determined quantity of hydrogen peroxide vapor, wherein said determined quantity of hydrogen peroxide vapor is obtained by sequentially injecting, with a given time interval (t) between two successive injections, a given dose of hydrogen peroxide in liquid form into the hot air; and a sterilization step consisting, for at least said time interval (t), of circulating hot air through said filtration means 12 to remove by evaporation all or part of the hydrogen peroxide deposited on said filtration means 12 during said application step.

[0272] The sterilization process consists first of all in a step of applying a gaseous mixture containing hydrogen peroxide in vapor form to the filtration means 12.

[0273] The application of the sterilizing agent formed by hydrogen peroxide is carried out by circulating, through the filtration means 12, a gaseous mixture consisting of hot air and a fraction of the determined quantity of hydrogen peroxide vapor.

[0274] According to an important characteristic, the gas mixture includes a fraction of the determined quantity of hydrogen peroxide vapor resulting from the sequential injection into hot air of a given dose of hydrogen peroxide in liquid form.

[0275] The injection of hydrogen peroxide in liquid form is carried out sequentially with a given time interval (t) between two successive injections.

[0276] To obtain said gaseous mixture, the process includes at least one step of vaporizing hydrogen peroxide.

[0277] The vaporization step consists of vaporizing said given dose of hydrogen peroxide in liquid form in evaporation means formed by the evaporator 46 to obtain said gaseous mixture used during the application step.

[0278] Advantageously, vaporization is achieved by injecting said given dose of hydrogen peroxide in liquid form into a continuous stream (or "stream") of hot air and then introducing the whole into the evaporator 46 to obtain said gaseous mixture used in the application step.

[0279] With a sterilization device 10 according to the example embodiment, the injection of said given dose of hydrogen peroxide during the vaporization step is obtained by selectively opening the regulating means 74 for a given period of time.

[0280] The opening of the regulating means 74 during the said given time period allows, for a determined flow rate of hydrogen peroxide in the injection line 52, the injection via the injection means 50 of the said desired given dose into the hot air circulating continuously through the fitting 48.

[0281] In the sterilization device 10, sequential injection is obtained by selectively closing said regulating means 74 during said interval (t) of given time between two successive injections of a given dose of liquid hydrogen peroxide.

[0282] As a non-limiting example, over a sequence with a total duration of thirty seconds, the control means 74 are commanded in the open position for a period of one second to inject said given dose into the hot air, and then are commanded in the closed position for a period of twenty-nine seconds.

[0283] During said time interval (t), no more hydrogen peroxide is injected by the injection means 50 and only the hot air delivered by the line 24 of the first circuit C1 continues to circulate, from the evaporator 46, through the line 60 and the filtration means 12.

[0284] It is at least during this interval (t) of time that the said sterilization step is carried out. Indeed, the sterilization step consists of circulating hot air through the said filtration means 12 to remove by evaporation all or part of the hydrogen peroxide previously deposited during the said application step.

[0285] Advantageously, hydrogen peroxide is deposited by condensation on the filtration means 12 during said application step.

[0286] Compared with continuous injection, sequential injection of a given dose of hydrogen peroxide allows a fraction of the determined quantity of hydrogen peroxide to be deposited on the filtration means 12.

[0287] The said given dose of hydrogen peroxide is determined in particular so as not to saturate, clog the means 12 of filtration.

[0288] Thanks to sequential injection, the fraction of said determined quantity of hydrogen peroxide vapor which condenses on the filtration means 12 is capable of being thermally activated and evaporated by the hot air during said time interval (t).

[0289] In a filtration device 10, the given dose of hydrogen peroxide in liquid form is introduced by hot air into the cavity 54 of the evaporator 46 where the hydrogen peroxide is then vaporized by the heating means 56.

[0290] The resulting gas mixture consists of hot air and a fraction of the determined quantity of hydrogen peroxide vapor which is then conveyed through the line 60 to the filtration means 12 to be sterilized.

[0291] The regulating means 62 are in the open position allowing the circulation of said gas mixture from the evaporator 46 to the filtration means 12.

[0292] The portion of the gas mixture that passes through said filtration means 12 is then evacuated via the evacuation line 64 towards the collection means 66, the regulation means 68 being in the open position.

[0293] Depending on the value of the time interval (t), the sterilization step which follows the application step allows all or part of the hydrogen peroxide condensates to be eliminated with hot air before proceeding to a new application step by injecting the next given dose.

[0294] When the value of the time interval (t) is too short to guarantee in particular a complete elimination of hydrogen peroxide, the sterilization process advantageously includes a sterilization step, called complementary, consisting of circulating only hot air through said filtration means 12 for a determined duration (D).

[0295] The additional sterilization step is carried out once the application, in the form of the said successively injected doses, of the desired quantity of hydrogen peroxide has been completed, which quantity corresponds for example to the capacity of the reservoir 76.

[0296] By way of non-limiting example, the additional sterilization step consists of circulating only hot air through the filtration means 12 for a duration D of between fifteen and forty minutes, preferably twenty-five minutes to ensure complete evaporation of hydrogen peroxide.

[0297] At least part of the "chemical" sterilization of the filtration means 12 according to the process therefore occurs during the time interval (t) and can, if necessary, be completed during such a supplementary sterilization step.

[0298] When the gaseous mixture brought in by the line 60 comes into contact with the filtration means 12, which are at a lower temperature, the hydrogen peroxide in the vapor state will then be deposited by condensation on the filtration means 12.

[0299] At the end of the application step, the filtration means 12 include at least on the surface hydrogen peroxide condensates resulting from the change of state, from vapor to liquid, which occurred when the hydrogen peroxide vapor contained in the gas mixture came into contact with said filtration means 12.

[0300] Once the said dose of hydrogen peroxide has been injected and vaporized in the evaporator 46, the duct 24 continues to deliver hot air at the set temperature (Tc).

[0301] This hot air passes through the evaporator 46 and continues its path through the sterilization device 10 until it comes into contact with the filtration means 12.

[0302] The hot air coming into contact with the filtration means 12 then presents, for example, a temperature between 100°C and 120°C which will gradually cause the evaporation of said hydrogen peroxide condensates.

[0303] Hot air thermally activates hydrogen peroxide (H2O2) by acting on the chemical bonds of hydrogen peroxide; by breaking these bonds, hot air causes the appearance of highly active free radicals (OH) which will destroy microorganisms and allow the desired sterilization to be achieved.

[0304] The hot air gradually evaporates the water present in the hydrogen peroxide condensates, which causes a gradual increase in the concentration of hydrogen peroxide and thereby increases the sterilizing effect.

[0305] Once evaporated, the hydrogen peroxide in gaseous state easily passes through the filtration means 12 without altering their structure.

[0306] Advantageously, the process includes a treatment step consisting of treating the effluents from sterilization and in particular hydrogen peroxide in gaseous form.

[0307] This is why the sterilization device 10 includes treatment means 70 arranged in the evacuation conduit 64, upstream of the collection means 66.

[0308] A sterilization cycle according to the process consists of successively repeating a number "n" of times the sequence made up of the said application and sterilization steps.

[0309] During a sequence of the sterilization cycle, the control means 74 are controlled to open to inject the determined dose of hydrogen peroxide, in the example via the injection means 50.

[0310] The application step is then carried out as previously described.

[0311] The 74 regulating means are then commanded to close during the time interval (t) in order to carry out the sterilization step.

[0312] Following the examples of values ​​indicated previously, for a sequence with a total duration of thirty seconds, the 74 regulation means are open for one second and then closed for twenty-nine seconds.

[0313] When the time interval (t) is relatively short as in the example above, an additional sterilization step is then carried out for example for a duration D of between fifteen and forty minutes, preferably twenty-five minutes.

[0314] As will be understood, the said additional sterilization step is however optional and could advantageously be eliminated by increasing the said time interval (t), for example to about five minutes between each injection of hydrogen peroxide.

[0315] Advantageously, the sequence of said application and sterilization steps is repeated a number "n" of times, for example between five and twenty-five times depending on the applications.

[0316] The repetition of the sequence is independent of the value of the time interval (t) and of the implementation of said additional sterilization step.

[0317] Preferably, the capacity of the reservoir 76 corresponds to the determined quantity of hydrogen peroxide required to repeat the sequence, i.e. to at least "n" times said given dose of hydrogen peroxide injected sequentially.

[0318] For a sterilization cycle, only one filling step is initially performed during the preliminary phase of preparing the sterilization device 10.

[0319] As explained previously, the alternating repetition of said application steps of a fraction of the determined quantity of hydrogen peroxide vapor from said given dose and hot air advantageously prevents the filtration means 12 from becoming saturated.

[0320] For an equal quantity of hydrogen peroxide vapor, the sterilization of the filtration means 12 obtained is thus better by successively carrying out "n" times the sequence formed of the said application and sterilization steps, than by projecting in one go an equivalent quantity of hydrogen peroxide vapor.

[0321] With sequential injection according to the sterilization process of the invention, the removal of hydrogen peroxide by evaporation using hot air requires comparatively less energy than would be required to evaporate an equivalent quantity that would be injected in a single step.

[0322] To evaporate an equivalent amount of hydrogen peroxide injected not sequentially but all at once, it would indeed be necessary to increase the temperature of the hot air, which would in turn increase the energy required, and also require increasing the flow rate of the hot air.

[0323] However, such an increase in temperature and / or hot air flow used in the sterilization process would have the consequence of potentially damaging the filtration means 12 as was previously the case with steam.

[0324] Advantageously, the sterilization process according to the invention therefore not only allows the filtration means 12 to be effectively sterilized but also prevents them from being damaged so that they can be used again after sterilization.

[0325] By preserving the filtration means 12, the sterilization process according to the invention advantageously increases their lifespan, which helps to reduce costs.

[0326] The process and device for sterilizing gas filtration means are intended in particular to be used for the sterilization of blow air filtration means in a manufacturing installation for thermoplastic containers from hot preforms.

Claims

1. Method for sterilizing gas filtration means, comprising at least: - an application step consisting in circulating, through the gas filtration means, a gaseous mixture comprising hot air and a determined quantity of hydrogen peroxide vapour, wherein said determined quantity of hydrogen peroxide vapour is determined as being necessary to sterilize the gas filtration means for a sterilization cycle; and - a sterilization step consisting in circulating hot air through said filtration means to eliminate by evaporation all or part of the hydrogen peroxide deposited on said filtration means during said application step; during the application step, said determined quantity of hydrogen peroxide vapour is obtained by injecting sequentially, with a given time interval (t) between two successive injections, a given dose of hydrogen peroxide in the liquid state into the hot air and in that said given dose is a fraction of the determined quantity and the sterilization step takes place during said time interval (t).

2. Sterilization method according to Claim 1, characterized in that the method comprises at least: - a vaporization step consisting in vaporizing said given dose of hydrogen peroxide in the liquid state in evaporation means to obtain said gaseous mixture used during the application step.

3. Sterilization method according to Claim 2, characterized in that the method comprises at least: - an injection step consisting in injecting sequentially, with said given time interval (t) between two successive injections, said given dose of hydrogen peroxide in the liquid state into a continuous stream of hot air and in introducing the whole into said evaporation means to obtain said gaseous mixture.

4. Sterilization method according to Claim 3, characterized in that the step of injecting said given dose of hydrogen peroxide is carried out sequentially by selectively commanding regulation means, respectively into an open position for a given time period and into a closed position for a given time interval (t) between two successive injections of said given dose of hydrogen peroxide in the liquid state.

5. Sterilization method according to any one of Claims 1 to 4, characterized in that the sterilization method consists in carrying out at least one cycle during which a sequence, comprising said application and sterilization steps, is repeated a number "n" of times.

6. Sterilization method according to Claim 5, characterized in that the method comprises at least: - an additional sterilization step consisting in circulating only hot air through said filtration means for a duration (D) that is determined as a function of the time interval (t) to ensure evaporation of the hydrogen peroxide.