Method and device for controlled and modulated ventilation of a confined space exposed to at least one pollutant, such as a fuel tank

Abstract

A controlled and modulated ventilation method for a confined space (2) exposed to at least one pollutant, comprising: - installation of an extraction duct (3) equipped with an extraction fan (30) and a supply duct (4) equipped with a supply fan (40); - continuous measurement of at least one environmental parameter representative of the confined space's internal environment, including at least one pollution level; - transmission of measurement data for at least one environmental parameter to a control unit (6); - real-time control and modulation of fan speeds based on measurement data, so as to modulate the extraction rate of stale air in the extraction duct and the supply rate of fresh air in the supply duct, at least according to the pollution level. Abstract figure: Figure 1

Description

Title of the invention: Method and device for controlled and modulated ventilation of a confined space exposed to at least one pollutant, such as a fuel tank technical field

[0001] The invention relates to a controlled and modulated ventilation method for a confined space exposed to at least one pollutant, and to a controlled and modulated ventilation device.

[0002] It relates more particularly to the controlled and modulated ventilation of a confined space within which human intervention is planned, with the aim of temporarily ventilating this confined space for the duration of the intervention in order to decontaminate and aerate the interior of the confined space to promote a healthy environment that complies with the requirements of the applicable standard.

[0003] The invention finds a favorite, and not limiting, application for the controlled and modulated ventilation of a fuel tank, and in particular an aircraft fuel tank or a fuel storage tank; other types of confined space subjected to at least one pollutant are of course conceivable within the framework of the present invention, such as, for example and not limited to, enclosed rooms such as clean rooms or laboratory rooms, industrial workshops (paint shops, maintenance workshops, etc.), and maritime or road transport containers. Previous technique

[0004] In a known manner, during human intervention inside an aircraft fuel tank (for maintenance, repair or cleaning purposes), it is known to use an extraction fan connected via a sleeve to an upstream orifice of the tank to extract / draw out the stale air, with fresh air entering through a downstream orifice by air intake.

[0005] However, such a solution has many limitations, whether in terms of safety for operators working inside the tank, efficiency and duration of air renewal, and performance in depolluting the inside of the fuel tank, in other words in improving the air quality inside the tank. Summary of the invention

[0006] The invention aims to resolve in whole or in part the aforementioned disadvantages by proposing a controlled and modulated ventilation process which ensures control of pollution control to offer increased safety.

[0007] Another object of the invention is to reduce the treatment time of the depollution, in order to allow a faster human intervention, and in particular to allow a treatment time on the order of an hour, between a few minutes and less than three hours.

[0008] Another object of the invention is to improve the renewal of air inside the confined space.

[0009] To this end, the invention proposes a controlled and modulated ventilation method for the controlled and modulated ventilation of a confined space exposed to at least one pollutant, comprising at least the following steps: - implementation of two air circulation paths between the inside of the confined space and the outside, including an extraction path on which at least one extraction fan is provided and a supply path on which at least one supply fan is provided; - activation of the extraction fan to extract stale air present in the confined space into the extraction duct and expel it to the outside; - activation of the blower fan to draw fresh air from outside into the blower path and blow it into the confined space (and for example into a privileged area of ​​this confined space, near an operator working inside this confined space); - continuous measurement, by a set of measurements, of at least one environmental parameter representative of the indoor environment of the confined space, at least one environmental parameter including at least one pollution rate corresponding to a concentration of at least one pollutant; - real-time communication of measurement data of at least one environmental parameter from the measurement set to a control / command unit which is linked to the exhaust fan and the supply fan; - real-time control and modulation, by the control unit, of an extraction fan speed and a supply fan speed as a function of measurement data of at least one environmental parameter and therefore at least as a function of measurement data of at least one pollution rate, so as to modulate an extraction flow rate of stale air in the extraction path and a supply flow rate of fresh air in the supply path at least as a function of at least one pollution rate.

[0010] Thus, the invention proposes to use both the exhaust fan to draw out the polluted, stale air, and the supply fan to force the introduction of fresh air and consequently improve air renewal. Furthermore, it is also proposed to modulate the stale air extraction rate according to at least the rate pollution levels are also addressed, and the fresh air supply flow rate can be adjusted accordingly. Thus, the higher the pollution level, the higher the extraction and supply flow rates will be, and conversely, the lower the pollution level, the lower the extraction and supply flow rates will be. This is advantageous for adapting the extraction and supply performance in real time based on the pollution level, thereby increasing safety. In other words, the extraction and supply flow rates will be modulated / adapted according to changes in the concentration of at least one pollutant in the confined space; thus, pollution level control constitutes monitoring of the risk to which the operator is exposed.

[0011] This solution therefore also allows for faster treatment of the confined space, generally in less than two hours for a maximum volume of 100 m3, by ensuring a high extraction and supply flow rate at the beginning of the treatment when the pollution level is high, then decreasing this extraction and supply flow rate as the pollution level decreases, in order to ultimately maintain a low pollution level in the confined space and an optimal air renewal rate.

[0012] In other words, the process ensures real-time controlled ventilation by acting on the exhaust fan and the supply fan, since the ventilation is controlled by real-time monitoring of the concentration of at least one pollutant, and also ensures modulated ventilation, since the extraction flow rate and the supply flow rate are modulated / adjusted according to the concentration of at least one pollutant.

[0013] According to one feature, at least one environmental parameter also includes an oxygen level, so that continuous measurement of the oxygen level inside the confined space is implemented, so that the control and modulation of the speed of the exhaust fan and the speed of the supply fan are carried out at least as a function of at least one pollution level and the oxygen level.

[0014] In this way, the oxygen level is also taken into consideration in order to adapt the extraction and supply to improve the oxygenation of the air inside the confined space, and thus reduce the risk of hypoxia for the operator. It should be noted that this oxygen level can be measured inside the confined space and / or outside the confined space at the extraction point.

[0015] According to another feature, at least one environmental parameter also includes an explosive flammability limit, so that continuous measurement of the explosive flammability limit is implemented inside the confined space, in order to control and modulate the speed of the exhaust fan and the speed of the blower fan should be carried out at least according to at least one pollution level and the explosive flammability limit.

[0016] Thus, the risk of explosive flammability is also taken into consideration for renewing the air inside the confined space. It should be noted that this explosive flammability limit can be measured inside the confined space and / or outside the confined space at the extraction route.

[0017] According to another feature, at least one environmental parameter also includes a hydrogen sulfide level, so that continuous measurement of the hydrogen sulfide level inside the confined space is implemented, so that the control and modulation of the speed of the exhaust fan and the speed of the supply fan are carried out at least as a function of at least one pollution level and the hydrogen sulfide level.

[0018] Thus, the hydrogen sulfide (H2S) level is also taken into account for air renewal within the confined space. This gas, hydrogen sulfide, can be measured using a specifically adapted sensor. This approach allows for precise adjustment of ventilation in response to hydrogen sulfide concentrations, thereby ensuring a controlled and safe environment. It should be noted that this hydrogen sulfide level can be measured inside the confined space and / or outside the confined space at the extraction point.

[0019] According to another feature, at least one environmental parameter also includes a carbon monoxide level, so that continuous measurement of the carbon monoxide level is implemented inside the confined space, so that the control and modulation of the exhaust fan speed and the supply fan speed are carried out at least as a function of at least one pollution level and the carbon monoxide level.

[0020] Thus, the carbon monoxide (CO) level is taken into account for air renewal within the confined space. This gas, carbon monoxide, can be measured using a specifically adapted sensor. This approach allows for precise adjustment of ventilation in response to carbon monoxide concentrations, thereby ensuring a controlled and safe environment. It should be noted that this carbon monoxide level can be measured inside the confined space and / or outside the confined space at the extraction duct.

[0021] According to another feature, at least one environmental parameter also includes an internal temperature, so that continuous measurement of the internal temperature is implemented inside the confined space, so that the control and modulation of the speed of the exhaust fan and the speed of the supply fan are carried out at least as a function of at least one pollution rate and the internal temperature.

[0022] In this way, the internal temperature is also taken into account for renewing the air inside the confined space; because safety parameters, such as the release rate of a pollutant like volatile organic compounds or certain toxic compounds, can depend on the internal temperature. In other words, it is preferable not to exceed a critical temperature, or evaporation temperature, beyond which the pollutant is released. It should be noted that this internal temperature can be measured inside the confined space and / or outside the confined space at the extraction point.

[0023] Furthermore, another advantage is the ability to control the speed of the blower fan to cool the confined space, in other words, to lower the internal temperature. With regard to this cooling, it is therefore possible to regulate the speed of the blower fan, while allowing temperature adjustments within the limits of the aforementioned safety parameters, such as remaining below the evaporation temperature of volatile organic compounds.

[0024] According to one possibility, the at least one pollutant comprises a chemical pollutant, selected from volatile organic compounds, volatile halogenated organic compounds, aldehydes, ammonia, and mercaptans.

[0025] In the case of a fuel tank, the monitored chemical pollutant could advantageously be one or more volatile organic compounds from the fuel.

[0026] In general, pollutant measurements must be adapted to the targeted pollutant, given that different detection techniques can be used. This adaptation of measurements makes it possible to implement controlled and modulated ventilation, thus ensuring a targeted and effective approach depending on the specific pollutant.

[0027] According to another possibility, at least one pollutant comprises a radioactive pollutant or a biological pollutant or an inorganic pollutant.

[0028] In other words, the process can also be applied in the case of radioactive (nuclear or radiological) pollution and / or biological pollution by monitoring one or more relevant biological markers.

[0029] In a particular embodiment, the method includes issuing an alert when at least one environmental parameter exceeds a predefined associated alert threshold.

[0030] In other words, it is planned to send an alert, for example to the person already present or soon to be present in the confined space, to inform him that at least one of the environmental parameters is above the corresponding alert threshold, thus enabling him to identify a risk.

[0031] This alert can, for example, be carried out by sending a sound signal, a text message, an email or a notification in a mobile application to a mobile device, such as a phone.

[0032] Advantageously, the method includes communicating, at given time intervals, to an operator the measurement of at least one environmental parameter.

[0033] In other words, the operator, such as the intervener, is regularly informed of the evolution of the monitored environmental parameter, or at least one of the monitored environmental parameters, in order to determine whether the conditions are favorable for remaining or entering the confined space safely.

[0034] This communication can, for example, be carried out by sending a text message, an email or a notification in a mobile application to a mobile device, such as a phone.

[0035] In a particular embodiment, the process includes, downstream of the extraction fan, a filtration of the stale air extracted in the extraction path, before discharge to the outside.

[0036] Thus, the stale air is treated by filtration before being released outside, in order to purify it before being released into nature.

[0037] According to one possibility, the filtration of the stale air is carried out through at least one filter medium in communication with a filtration fan which draws the stale air through the at least one filter medium to expel it outside.

[0038] In this way, this filtration fan is placed in series with the extraction fan, with at least one filter medium thus being interposed between these two fans.

[0039] The use of this exhaust fan advantageously compensates for the pressure drop across at least one filter medium, thus ensuring that the filtration fan's efficiency is maintained without degradation. This exhaust fan therefore contributes to optimizing the system to ensure consistent performance.

[0040] Advantageously, the control / command unit controls and modulates a speed of the filtration fan so that the air flow rate at the outlet of the filtration fan is equivalent to the extraction flow rate of the stale air in the extraction path.

[0041] Thus, the filtration fan and the exhaust fan are controlled by the control unit so that these two fans operate synchronously with the same flow rates (and, for example, at the same motor speed if the fans are equivalent) to ensure proper system operation. This synchronization ensures consistency in the airflow and contributes to the overall efficiency of the system.

[0042] According to one variant, at least one filter medium is an activated carbon-based medium, particularly well suited for the filtration of volatile organic compounds.

[0043] Advantageously, the adsorption capacity of the filter medium, and for example of the activated carbon-based medium, is between 0.1 and 20 m3.

[0044] Advantageously, at least one upstream sensor and at least one downstream sensor are disposed respectively upstream and downstream of at least one filter medium and measure respectively an upstream pollution rate and a downstream pollution rate corresponding to a concentration of at least one pollutant upstream and downstream of at least one filter medium, and furthermore the control unit receives measurement data of the upstream pollution rate and the downstream pollution rate from at least one upstream sensor and at least one downstream sensor.

[0045] Thus, the control unit monitors, and optionally records, the upstream and downstream pollution level measurement data, thereby enabling the establishment of a pollution balance and the monitoring of contamination levels in the filter media. This data makes it possible to predict and detect any overload or saturation of the filter media, allowing appropriate corrective measures to be taken to ensure efficient filtration operation.

[0046] According to one possibility, a carbon monoxide sensor can be provided at the level of at least one filter medium, which has the advantage of being able to determine a possible start of fire in the filter medium.

[0047] According to one possibility, the control / command unit activates an alert when the downstream pollution level exceeds a critical concentration threshold and / or when a difference between the upstream pollution level and the downstream pollution level is less than a minimum filtration threshold.

[0048] Thus, when the downstream pollution level exceeds a critical concentration threshold (i.e., when the pollution level discharged outside is too high) and / or when the adsorption capacity of the filter media is about to be exceeded (i.e., when the difference between the upstream and downstream pollution levels is too small), an alert is triggered to signal the need to replace or inspect the filter media. This alert ensures optimal filtration operation by guaranteeing that the filter media is regularly replaced to maintain its effectiveness.

[0049] Such an alert can, for example, be effected by sending a sound signal, a text message, an email or a notification in a mobile application to a mobile device, such as a telephone.

[0050] In another embodiment, at least one saturation sensor measures a saturation rate of at least one filter medium, and furthermore the control / command unit receives measurement data of the saturation rate of at least one filter medium from at least one saturation sensor.

[0051] Thus, the control / command unit monitors, and possibly records, measurement data of the saturation rate of at least one filter medium (for example as a percentage or quantity of pollutant trapped in the filter medium), thus allowing a level of filling or saturation of this at least filter medium to be established, and therefore the remaining capacity of this at least filter medium to be estimated, thus offering a precise evaluation of the available trapping space in real time.

[0052] According to one possibility, the control / command unit activates an alert when the saturation rate of at least one filter medium exceeds a critical saturation threshold.

[0053] Such an alert can, for example, be effected by sending a sound signal, a text message, an email or a notification in a mobile application to a mobile device, such as a telephone.

[0054] According to one feature, at least one temperature probe is disposed on or near at least one filter medium in order to measure a temperature of at least one filter medium, and furthermore the control unit receives temperature measurement data of at least one filter medium from the temperature probe.

[0055] Thus, the control / command unit follows, and possibly records, the temperature measurement data of the filter medium, as it is advantageous to continuously monitor the temperature of the filter medium (such as activated carbon) in order to detect any abnormal increase that could indicate an exothermic reaction.

[0056] According to another feature, the control unit drives the filtration fan according to a given ventilation setpoint when the temperature of at least one filter medium exceeds a critical temperature threshold.

[0057] Thus, the filtration fan applies the ventilation setpoint to ensure proper ventilation of the filter media, for efficient dissipation of the heat generated by the overheating filter media. For example, the ventilation setpoint may correspond to the nominal operating speed of the filtration fan to dissipate this heat.

[0058] According to another feature, an upstream controlled valve and a downstream controlled valve are arranged respectively upstream and downstream of at least one filter medium, and furthermore the control / command unit is connected to the upstream controlled valve and the downstream controlled valve and commands their closures in the event of a stop of the extraction fan.

[0059] Thus, the control unit automatically closes these two controlled valves in the event of a stop of the extraction fan, thereby isolating at least one filter medium to prevent any leakage of pollutant, in particular in the event of a temperature rise.

[0060] In an advantageous embodiment, the process implements at least two successive phases comprising: - a start-up phase in which the exhaust fan speed and the supply fan speed are controlled to be at a maximum exhaust fan speed and a maximum supply fan speed respectively, until at least one environmental parameter is within a predefined safe range; and - a working phase in which the speed of the extraction fan and the speed of the supply fan are controlled and modulated in real time according to at least one environmental parameter.

[0061] Thus, during the start-up phase at the beginning of the process, the exhaust and supply fans operate at their maximum speeds to promote rapid air renewal, before entering the working phase where the exhaust and supply fans operate at reduced speeds for the operator's comfort, but still with real-time control and modulation of their speeds. It should be noted that, during the start-up phase, the operator(s) are not authorized to enter the confined space; and it is only once this start-up phase is completed that they are authorized to enter the confined space during the working phase.

[0062] Furthermore, during the working phase, the speed of the extraction fan and the speed of the blowing fan do not exceed respectively the maximum speed of the extraction fan and the maximum speed of the blowing fan.

[0063] The invention also relates to the possibility of having fresh air heated before being blown into the confined space.

[0064] Such heating makes it possible to have an environment at an acceptable and comfortable ambient indoor temperature for the operator, for example between 18 and 25 °C.

[0065] The operator may have the option of regulating the blowing speed of the heated fresh air as needed. Similarly, the indoor temperature may be adjusted, for example within a range of 18 to 25 °C.

[0066] Heating is provided by a heating system placed on the supply path, which can operate by means of heating resistors, allowing for example to heat the fresh air from -10°C to 25°C in winter.

[0067] According to one possibility, a non-return valve is placed on the blowing path, between the confined space and the heating system, and thus ensures safety by preventing the penetration of kerosene vapors in the event of a stop of the blowing fan, avoiding any contact with the heating system, and therefore avoiding any risk of fire or explosion.

[0068] According to one possibility, the method includes measuring the internal temperature inside the confined space, and controlling the heating of the fresh air so that the internal temperature remains within a predefined temperature range.

[0069] According to one feature, the method includes a measurement of an outside temperature, which corresponds to the temperature of the fresh air before heating, and in which the control of the heating of the fresh air is operated as a function of the indoor temperature and the outdoor temperature.

[0070] Thus, by also taking into account the outside temperature, the heating makes it possible to reach the target temperature precisely and efficiently.

[0071] According to another feature, the control of the fresh air heating is operated according to measurement data of at least one pollution rate.

[0072] Indeed, when a pollutant is temperature-sensitive, as is the case with volatile organic compounds, it is advantageous to take into account the measured pollution level to prevent any undesirable evaporation of the pollutant, and therefore to adjust the heating system to avoid an increase in this pollution level. Furthermore, as previously mentioned, the speed of the exhaust fan and the speed of the supply fan are also controlled and modulated according to this pollution level.

[0073] For example, the potential evaporation caused by the heated fresh air is monitored by measuring the level of volatile organic compounds, and the heating is adjusted accordingly. Furthermore, the exhaust fan is controlled to compensate for this evaporation, thus maintaining the integrity of the ventilation system.

[0074] According to one possibility, the installation of the two air circulation paths includes a sealed and temporary mounting of a connecting piece on an access hatch provided on the confined space, said connecting piece having two passages for the two air circulation paths.

[0075] In other words, the two air circulation paths are temporarily connected on the access hatch, for the duration of the air treatment and intervention.

[0076] According to one possibility, the extraction of stale air present in the confined space by the extraction fan is carried out with an extraction air flow rate of between 500 and 20000 m3 per hour.

[0077] According to one feature, the extraction of stale air present in the confined space by the extraction fan is carried out with an extraction air flow rate of between 500 and 15000 m3 per hour.

[0078] It should be noted that it is possible to provide one or more extraction fans, in series or in parallel, depending on the desired extraction flow rate.

[0079] According to one feature, the measuring assembly includes at least one portable measuring device that is in radio communication with the control / command unit, said portable measuring device incorporating one or more sensors conditioned for measuring at least one environmental parameter including at least one pollution level.

[0080] Such a portable measuring device is advantageous because it can be worn by an operator working inside the confined space, thus allowing monitoring of at least one environmental parameter (and therefore of at least one pollution level) directly at the level of that operator.

[0081] This portable measuring device may, for example, be a multi-gas detector that combines the detection / measurement of several gases, such as, for example and without limitation, volatile organic compounds (VOCs), with the possibility of adding other measuring cells adapted to the targeted pollutants, as well as the oxygen level. This portable measuring device may also include a cell for measuring the explosive flammability limit.

[0082] This custom-designed portable measuring device is battery-operated and incorporates radio communication and real-time monitoring functionalities. Radio communication between the portable measuring device and the control unit can be carried out using various protocols, such as, but not limited to, 3G, 4G, 5G, Bluetooth©, WiFi©, LoRa©, etc.

[0083] According to another feature, the measuring assembly includes at least one fixed measuring device which is in wired communication with the control / command unit and which includes a measuring chamber which is in fluidic communication with the confined space or with the extraction route, and which integrates one or more sensors conditioned for a measurement of at least one environmental parameter including at least one pollution rate.

[0084] Such a fixed measuring device is advantageous because it allows for stable operation due to the wired communication with the control unit. Such a fixed measuring device also makes it possible to collect and analyze a sample of the stale air present inside the confined space or in the extraction duct, without an operator having to enter.

[0085] Furthermore, and compared to the portable measuring device described above, in the event of a network and / or battery problem, the fixed measuring device guarantees the secure control of the ventilation, thus ensuring operational continuity even in the event of connectivity disruption.

[0086] This fixed measuring device also offers the user the possibility of manually entering measurement variables, such as CO, H2S, VOC, O2 levels and the explosive flammability limit, in case of network problems. This operation can be easily performed using a direct reading on the portable measuring device and then manually entering the data into the control unit. This is particularly useful in the case of a portable measuring device not equipped with a network connection or in a network failure situation.

[0087] This fixed measuring device may include an air pump to pump the stale air towards the measuring chamber.

[0088] Advantageously, the fixed measuring device includes a distributor upstream of the measuring chamber, this distributor having a first communication inlet with the confined space or with the extraction route, and a second communication inlet with the outside, so as to be able to put the measuring chamber in communication either with the confined space or with the extraction route, or with the outside.

[0089] Thus, the distributor is used to draw clean air from outside at regular intervals, instead of stale air. By drawing this clean air, which is directed into the measurement chamber, the lifespan of the sensors is increased, their optimal sensitivity is maintained (thus preventing saturation of the detection cell), and their response times are maintained at optimal levels. Indeed, by drawing clean air at regular intervals, the sensors' exposure to pollutants is reduced, which helps to extend their operational lifespan. Furthermore, by keeping the sensors in a clean air environment between measurements, it is ensured that they are ready to detect the gases of interest without being influenced by residues from previous measurements.

[0090] Sampling clean air at the chamber level thus plays an important role in increasing both the lifespan and sensitivity of the sensors. By doing so, not only is the performance of the sensors preserved in the long term, but it also makes it possible to detect any potential leaks in the equipment. Furthermore, this measure provides the possibility of monitoring the outside air quality in real time, thereby allowing verification of the quality of the fresh air supplied to the confined space by the supply fan. This helps to ensure a safe and controlled environment at all times.

[0091] In a particular embodiment, the measurement of at least one environmental parameter is implemented by the fixed measuring device at least during the start-up phase.

[0092] Indeed, at startup, it is recommended, or even mandatory, that no one enter the confined space. In this case, the measurement of at least one environmental parameter is carried out by the fixed measuring device, in its measuring chamber, to determine the pollution level. In this way, this fixed measuring device makes it possible to know if or when this pollution level is below a tolerable threshold that would allow an operator to enter the confined space.

[0093] According to an advantageous embodiment, the method includes a transmission, by the control / command unit and to a remote server, of usage data including at least measurement data of at least one environmental parameter and ventilation data including data relating to the speeds of the extraction fan and the supply fan and / or data relating to the extraction and supply flow rates, for storage and history recording on this remote server of this usage data.

[0094] Thus, this history recording of this usage data makes it possible to access the conditions in which the operator(s) worked inside the confined space, and to concretely assess the effectiveness of the controlled and modulated ventilation thanks to the measurement data of at least one environmental parameter and the ventilation data, in order for example to refine certain parameters to improve ventilation during a future session.

[0095] Advantageously, the process includes the production of an activity report at the end of the controlled and modulated ventilation process, including at least the usage data.

[0096] Such an activity report is therefore generated at the end of the activity, that is, once the controlled and modulated ventilation has stopped. Furthermore, such an activity report can also be generated at the request of the user or the owner of the confined space. This activity report provides, in particular, a summary: - measurement data of at least one environmental parameter, including at least one pollution level (such as volatile organic compounds (VOCs), toxic gases (such as H2S and CO), as well as oxygen levels and explosive flammability limits; and - ventilation data used and - results obtained.

[0097] This activity report therefore allows for a retrospective evaluation of the effectiveness of the controlled and modulated ventilation and verification of compliance with safety standards. The activity report may also contain additional data on temperature, pressure, and humidity conditions, as well as on air exchange rates and air velocity around the operator. This additional data is advantageous for assessing the overall environment in which the ventilation operation took place.

[0098] According to one feature, the method comprises selecting a confined space model from among several confined space models, in which, for each of the several models, instructions are associated for the control unit regarding the speeds of the exhaust and supply fans and / or the exhaust and supply flow rates, so that the control unit applies the instructions of the confined space model selected during the control and modulation step.

[0099] Indeed, depending on the confined space model, the instructions (or rules) for adjusting the speeds of the exhaust fan and the supply fan, and / or for modulating the exhaust and supply airflow rates, based on at least one environmental parameter, may vary, as they depend, for example, on the volume, shape, or dimensions of the confined space, as well as space constraints and areas that are difficult to ventilate. Such instructions, specific to each confined space model, are essentially recipes designed to ensure adequate air circulation and guarantee an optimal and personalized level of ventilation to maintain a safe environment inside the confined space.

[0100] Advantageously, for each of the several models there are associated recommendations regarding the locations of the two traffic lanes.

[0101] Thus, the installer will be informed of the most suitable locations for the two traffic lanes according to the confined space model, always with the aim of ensuring an optimal level of ventilation.

[0102] Advantageously, the exhaust air flow rate is measured by a dedicated device at the outlet of the exhaust fan, thus ensuring an optimal flow rate. This flow rate measurement prevents any potential degradation due to duct fouling or compression, alerting the operator to check the duct layout. This feature also proves effective in preventing performance degradation of the ventilation system.

[0103] In a favorite and non-limiting application, the confined space is a fuel tank, and for example a fuel tank of an aircraft.

[0104] The invention also relates to a controlled and modulated ventilation device for a confined space exposed to at least one pollutant, comprising: - two air circulation paths comprising an extraction path on which at least one extraction fan is provided and a supply path on which at least one supply fan is provided; - a measurement system equipped with at least one sensor designed for continuous measurement of at least one environmental parameter representative of the confined space's internal environment, at least one environmental parameter including at least one pollution level corresponding to a concentration of at least one pollutant; and - a control unit connected to the measuring assembly, the exhaust fan and the supply fan, said control unit being programmed to control and modulate in real time a speed of the exhaust fan and a speed of the supply fan according to data from measurement of at least one environmental parameter, and therefore at least based on measurement data of at least one pollution rate.

[0105] Such a controlled and modulated ventilation system thus makes it possible to implement the process described above. This controlled and modulated ventilation system is particularly suitable for meeting the "ATEX" certification requirements specific to explosive atmospheres. Depending on the application, this controlled and modulated ventilation system can also be offered in a version that does not conform to "ATEX" certification in order to meet the diverse needs of users. Brief description of the drawings

[0106] Other features and advantages of the present invention will become apparent from the following detailed description of a non-limiting example of implementation, made with reference to the accompanying figures in which:

[0107] [Fig.l] is a schematic view of a controlled and modulated ventilation device for implementing a ventilation process for a confined space exposed to at least one pollutant;

[0108] [Fig.2] is a schematic view of an example of a fixed measuring device with measuring chamber.

[0109] [Detailed description of embodiments of the invention]

[0110] With reference to [Fig. 1], a controlled and modulated ventilation device 1 adapted for implementing a controlled and modulated ventilation process for a confined space 2 exposed to at least one pollutant, comprises two air circulation paths 3, 4 between the interior of the confined space 2 and the exterior EXT, comprising: - an extraction path 3 on which an extraction fan 30 is provided, so that activation of the extraction fan 30 allows stale air present in the confined space 2 to be extracted into the extraction path 3 and discharged to the outside EXT; and - a supply path 4 on which a supply fan 40 is provided, so that the activation of the supply fan 40 allows fresh air to be drawn into the supply path 4 from the outside EXT and blown into the confined space 2.

[0111] The installation of the two air circulation paths 3, 4 may include a sealed and temporary mounting of a connecting piece 10 on an access hatch 20 provided on the confined space 2, such a connecting piece 10 having two passages for the two air circulation paths 3, 4.

[0112] The controlled and modulated ventilation device 1 includes, downstream of the extraction fan 30, a filtration system 7 for filtering the stale air extracted in the extraction path 3, before discharge to the outside EXT.

[0113] This filtration system 7 comprises: - at least one filter medium 71 (for example, an activated carbon-based medium) for filtering stale air through this filter medium 71; and - a filtration fan 70, in communication with the filter medium 71 to draw the foul air through this filter medium before expelling it to the outside EXT.

[0114] The filtration system 7 may also include an upstream sensor 72 and a downstream sensor 73 arranged respectively upstream and downstream of the filter medium 71 and which respectively measure an upstream pollution level and a downstream pollution level corresponding to a concentration of at least one pollutant upstream and downstream of the filter medium 71. Thus, this dual measurement with the sensors 72, 73 makes it possible to estimate the efficiency of the filtration.

[0115] The filtration system 7 also includes: - a saturation sensor 74 which measures a saturation rate of the filter medium 71, in order to determine if this filter medium 71 is saturated and needs to be replaced; - at least one temperature probe 75 disposed on or near the filter medium 71 in order to measure a temperature of the filter medium 71.

[0116] The filtration system 7 includes an upstream controlled valve 76 and a downstream controlled valve 77 which are arranged respectively upstream and downstream of the filter media 71; these controlled valves 76, 77 may be of the solenoid valve type, and which are either open or closed.

[0117] The filtration system 7 may also include a carbon monoxide sensor to measure a carbon monoxide level at the level of the filter media 71, in order to be able to determine a fire originating in the filter media 71.

[0118] The controlled and modulated ventilation device 1 includes a heating system 41 placed on the supply path 40 to heat the fresh air which is blown into the confined space 2. A non-return valve 42 is placed on the supply path 40, between the confined space 2 and the heating system 41, in order to prevent a backflow of stale air towards the heating system 41, in particular when the supply fan 40 is off.

[0119] The controlled and modulated ventilation device 1 includes a measuring assembly 5 equipped with at least one sensor conditioned for continuous measurement of at least one environmental parameter representative of the internal environment of the confined space 2.

[0120] More specifically, the measuring assembly 5 comprises at least one sensor 51 configured for continuous measurement of a pollution level corresponding to a concentration of at least one pollutant, this pollution level being considered here as an environmental parameter. If the confined space 2 is exposed to several pollutants, the measuring assembly 5 comprises several sensors 51 configured for Measure the respective pollution levels of the different pollutants. At least one pollutant must be a chemical pollutant, chosen from volatile organic compounds, volatile halogenated organic compounds, aldehydes, ammonia, and mercaptans. Note that the measurement can be taken at the confined space 2 and / or at the extraction line 3.

[0121] Measurement set 5 also includes: - a sensor 52 configured for continuous measurement of an oxygen level inside the confined space 2, considered as an environmental parameter; - a sensor 53 configured for continuous measurement of an explosive flammability limit inside the confined space 2, considered as an environmental parameter; - a sensor 54 configured for continuous measurement of an internal temperature inside the confined space 2, considered as an environmental parameter.

[0122] The measuring assembly 5 may also include: - a sensor 55 configured for continuous measurement of a hydrogen sulfide level inside the confined space 2, considered as an environmental parameter; - a sensor 56 configured for a continuous measurement of carbon monoxide levels inside the confined space 2, considered as an environmental parameter.

[0123] In the illustrated example, these sensors 51-56 are part of a fixed measuring device 57. These sensors 51-56 can operate their respective measurements either at the level of the confined space 2 (i.e. inside the confined space 2) or at the level of the extraction path 3 (i.e. outside the confined space 2, by taking air from the extraction path 3 which comes from inside the confined space 2).

[0124] With reference to [Fig. 2], this fixed measuring device 57 may include a measuring chamber 570 which is in fluidic communication with the confined space 2 or with the extraction path 3 and which incorporates one or more sensors configured for measuring all or part of the environmental parameters described above. In other words, the measuring chamber 570 may incorporate all or part of the sensors 51-56 described above. In the example illustrated in [Fig. 2], the measuring chamber 570 is in fluidic communication with the extraction path 3.

[0125] This fixed measuring device 57 includes a distributor 571 upstream of the measuring chamber 570, this distributor 571 having a first inlet 572 in communication with the extraction path 3 (or alternatively with the confined space 2), and a second inlet 573 in communication with the outside EXT, so as to be able to put the measuring chamber 570 in communication either with the extraction path 3 (or alternatively with the confined space 2), or with the outside EXT, as well as an output in communication with the measuring chamber 570.

[0126] This fixed measuring device 57 includes an air pump 574 for pumping the stale air towards the measuring chamber 570, and for expelling it to the outside EXT.

[0127] When the distributor 571 connects its first inlet 572 to its outlet, and thus connects the measuring chamber 570 with the extraction path 3 (or alternatively with the confined space 2), then measurements can be taken using the sensor(s) 51-56 present in the measuring chamber 570. When the distributor 571 connects its second inlet 573 to its outlet, and thus connects the measuring chamber 570 with the outside EXT, then clean air enters the measuring chamber 570, thus preventing saturation of the sensor(s) 51-56 present in the measuring chamber 570, which affects their lifespan, sensitivity, and response time.

[0128] The measurement assembly 5 may also include a portable measuring device 58 suitable for being worn by an operator, and which integrates one or more sensors configured for measuring all or part of the environmental parameters described above, in addition to all or part of the measurements carried out by the sensors 51-56 of the fixed measuring device 57. This portable measuring device 58 is equipped with a radio communication module 59, for example in 3G, 4G, 5G, Bluetooth©, WiFi©, LoRa©, etc.

[0129] The controlled and modulated ventilation device 1 comprises a control unit 6 (for example, of the PLC or processor type) connected to the measuring assembly 5 (and thus to its various sensors 51-56 as well as the sensors of the portable measuring device 58). More specifically, the control unit 6 is wired to the fixed measuring device 57, and where applicable, it is wirelessly connected to the portable measuring device 58.

[0130] Thus, the measurement data of T at least one environmental parameter, and more specifically the measurement data from the sensors 51-56 of the fixed measuring device 57 and the sensors of the portable measuring device 58, are communicated to this control / command unit 6.

[0131] The control unit 6 is also linked to the extraction fan 30, the blowing fan 40 and the filtration fan 70, so as to control their operation (inactive mode and active mode) and in particular to control the speeds of these three fans 30, 40, 70.

[0132] This control unit 6 is programmed to control and modulate in real time the speed of the exhaust fan 30 and the speed of the supply fan 40 as a function of measured data of T, at least one environmental parameter, and therefore at least as a function of measured data of T, at least one pollution level from sensor 51 (or sensors 51 if several levels of pollution are measured), so as to modulate an extraction rate of stale air in the extraction path 3 and a supply rate of fresh air in the supply path 4 at least according to at least one pollution rate.

[0133] Advantageously, a flow meter is provided in the extraction path 3 and a flow meter in the supply path 4, in order to measure respectively the extraction flow rate of the stale air in the extraction path 3 and the supply flow rate of the fresh air in the supply path 4. These flow meters can be of different types, such as for example hot wire velocity probe, Pitot probe or propeller probe.

[0134] This real-time control and modulation of the speed of the exhaust fan 30 and the speed of the supply fan 40 by the control unit 6 is thus carried out at least according to the pollution level (or levels), and it can also be carried out according to: - the oxygen level measured by sensor 52 and / or by a dedicated sensor integrated into the portable measuring device 58; and / or - the explosive flammability limit measured by sensor 53 and / or by a dedicated sensor integrated into the portable measuring device 58; and / or - of the internal temperature measured by sensor 54 and / or by a dedicated sensor that is integrated into the portable measuring device 58; and / or - the hydrogen sulfide concentration measured by sensor 55 and / or by a dedicated sensor integrated into the portable measuring device 58; and / or - the carbon monoxide level measured by sensor 56 and / or by a dedicated sensor which is integrated into the portable measuring device 58.

[0135] More specifically, the control / command unit 6 is configured to first implement a start-up phase, before the operator enters the confined space 2, in which the speed of the exhaust fan 30 and the speed of the blower fan 40 are controlled (or adjusted) to be respectively at a maximum speed of the exhaust fan 30 and at a maximum speed of the blower fan 40, until at least one environmental parameter is within a predefined safe range, and more particularly until at least one pollution level is below a low threshold which complies with the applicable safety standards.

[0136] The measurement of the environmental parameter(s) taken into consideration during this start-up phase (and in particular the measurement of the pollution rate(s)) is implemented by the fixed measuring device 57; insofar as the operator has not yet entered the confined space with his portable measuring device 58.

[0137] In advance, it is possible to select a confined space model from among several confined space models. In a favorite application, confined space 2 is a fuel tank, and for example a fuel tank of an aircraft. Thus, for each aircraft model, a fuel tank model can be associated, with its specificities in terms of volumes and sources of pollutant emission which may not be the same in terms of size, volume and / or type of pollutant.

[0138] Thus, the maximum speed of the extraction fan 30 and the maximum speed of the supply fan 40 can be established according to the selected model, to correspond specifically to the confined space 2. Furthermore, for each of the several confined space models, recommendations regarding the locations of the two traffic lanes 3, 4 can be associated.

[0139] Following the start-up phase, the control unit 6 is configured to implement a working phase, during which the operator is inside the confined space 2, and in which the speed of the extraction fan 30 and the speed of the blowing fan 40 are controlled and modulated in real time according to at least one environmental parameter, and in particular according to the pollution rate (or rates of pollution) and any other environmental parameters mentioned above.

[0140] Thus, in the working phase, the extraction rate of stale air in the extraction path 3 and the supply rate of fresh air in the supply path 4 are controlled and modulated dynamically, in real time, in response to measurement data from the measurement set, and in particular from the various sensors 51-56, as well as from the sensors of the portable measuring device 58 if the operator is equipped with it when entering the confined space 2, and based on the flow measurements made by the flow meters placed in the supply path 4 and in the extraction path 3; so as to ensure the maintenance of a low concentration of the pollutant or each of the pollutants in the confined space 2 and an optimal air renewal rate.

[0141] This real-time control and modulation of the fan speeds 30, 40 allows the extraction and supply flow rates to be adjusted precisely, preferably remaining below the maximum speeds, because high flow rates could further stimulate liquid sources of pollutants (such as kerosene which is likely to outgas and therefore release pollutants such as volatile organic compounds), hence the interest in adapting these extraction and supply flow rates to avoid an increase in the concentration of vapors (and therefore for example volatile organic compounds) in the confined space 2.

[0142] Modulation based on the internal temperature is advantageous, because an increase in the internal temperature beyond a certain temperature threshold could lead to such degassing and therefore a release of polluting vapor (and therefore dangerous for the operator).

[0143] Such a temperature threshold can be established for each of the several confined space models, since this temperature threshold can depend on the volume and the sources of pollutant emission specified for each of the confined space models.

[0144] The supply fan 40 is used to blow fresh air, thereby contributing to the extraction of stale air and the purification of the air inside the confined space 2. It also creates a pleasant and refreshing airflow in the confined space 2 for the operator's comfort. However, during winter or cold periods, the supply fan 40 can be used to blow warm air, for example at approximately 20°C, in combination with the heating system 41, in order to maintain the internal temperature within a predefined temperature range.

[0145] Also, the control unit 6 is connected to this heating system 41 in order to control it and regulate the heating of the fresh air supplied by the blower fan 40. An outdoor temperature sensor 43, located outside (EXT), may be provided to measure an outside temperature, which therefore corresponds to the temperature of the fresh air before heating. The control unit 6 is thus connected to this outdoor temperature sensor 43 as well as to the sensor 54, which continuously measures the indoor temperature inside the confined space 2. The control unit 6 then regulates the heating of the fresh air based on the indoor and outdoor temperatures.

[0146] This heating control can also take into account measurement data of at least one pollution rate, since the release of the pollutant may depend on the temperature; as described previously, with liquid kerosene which degasses and releases pollutants, such as volatile organic compounds, beyond a given temperature threshold.

[0147] With regard to the filtration of the stale air, the control unit 6 is connected to the filtration system 7, and more specifically is connected to the filtration fan 70 in order to control and modulate the speed of the filtration fan 70. Advantageously, to ensure a constant flow rate between the filtration fan 70 and the extraction fan 30, the control unit 6 controls and modulates the speed of the filtration fan 70 so that the air flow rate at the outlet of the filtration fan 70 is equivalent to the extraction flow rate of the stale air in the extraction path 3.

[0148] The control / command unit 6 is connected to the upstream sensor 72 and the downstream sensor 73 to retrieve measurement data of the upstream pollution rate and a downstream pollution rate, and the control / command unit 6 activates an alert when the downstream pollution rate exceeds a critical concentration threshold and / or when a difference between the upstream pollution rate and the downstream pollution rate is less than a minimum filtration threshold.

[0149] The control / command unit 6 is connected to the saturation sensor 74 to retrieve measurement data of the saturation rate of the filter media 71, and the control / command unit 6 activates an alert when this saturation rate exceeds a critical saturation threshold.

[0150] The control / command unit 6 is connected to the temperature probe 75 to retrieve the temperature measurement data of the filter media 71, and the control / command unit 6 controls the filtration fan 70 according to a given ventilation setpoint when the temperature of the filter media 71 exceeds a critical temperature threshold.

[0151] The control / command unit 6 is connected to the upstream controlled valve 76 and the downstream controlled valve 77 to control their closures in the event of a stop of the extraction fan 30, and thus prevent a leakage of stale and polluted air to the outside EXT.

[0152] During the working phase, the control unit 6 is configured to issue an alert when at least one environmental parameter exceeds a predefined associated alert threshold, and in particular: - the pollution level (or one of the pollution levels) exceeds a pollution alert threshold; - the oxygen level exceeds an oxygen alert threshold - the explosive flammability limit exceeds a flammability alert threshold - the indoor temperature exceeds a temperature alert threshold; - the hydrogen sulfide level exceeds a hydrogen alert threshold; - carbon monoxide levels exceed a carbon monoxide alert threshold.

[0153] During the working phase, the control / command unit 6 is configured to communicate data on a mobile terminal 60 (for example a phone, a tablet, a personal digital assistant) carried by the operator who is inside the confined space 2.

[0154] The control / command unit 6 communicates, at given time intervals, to the operator on their mobile terminal 60 the measurement of at least one environmental parameter, or even the measurements of all environmental parameters. The alert, issued by the control / command unit 6 when at least one of the environmental parameters exceeds the associated alert threshold, is preferably transmitted to the operator on their mobile terminal 60, in order to inform them of the risk, and possibly to inform them that they must leave the confined space 2 and / or equip themselves with protective equipment (such as a gas mask).

[0155] Furthermore, at least during the working phase (and possibly also during the start-up phase), the control / command unit 6 transmits (for example by radio communication) to a remote server 61 usage data including: - at least measurement data for at least one environmental parameter (or even measurement data for all environmental parameters) and - ventilation data including data relating to the speeds of the extraction fan 30 and the supply fan 40 and / or data relating to extraction and supply flow rates; for storing and recording this usage data on this remote server 61.

[0156] At the end of the controlled and modulated ventilation process, and therefore at the end of the work phase (after the operator has left the confined space 2), an activity report 62 is generated and includes at least the usage data. Thus, the usage data collected and related to the intervention will be used to automatically generate this activity report 62, including all data relating to the intervention, including temporal and spatial data, volumes treated, nature of pollutants, anomalies, etc.

Claims

1. Demands Controlled and modulated ventilation method for controlled and modulated ventilation of a confined space (2) exposed to at least one pollutant, comprising at least the following steps: - installation of two air circulation paths (3, 4) between the inside of the confined space (2) and the outside (EXT), including an extraction path (3) on which at least one extraction fan (30) is provided and a supply path (4) on which at least one supply fan (40) is provided; - activation of the extraction fan (30) to extract into the extraction path (3) stale air present in the confined space (2) and expel it to the outside (EXT); - activation of the blower fan (40) to draw fresh air from outside (EXT) into the blower path (4) and blow it into the confined space (2); - continuous measurement, by a set of measurements (5), of at least one environmental parameter representative of the internal environment of the confined space (2), at least one environmental parameter including at least one pollution rate corresponding to a concentration of at least one pollutant; - real-time communication of measurement data of at least one environmental parameter, including at least measurement data of at least one pollution rate, from the measurement set (5) to a control / command unit (6) which is linked to the exhaust fan (30) and the supply fan (40); - real-time control and modulation, by the control unit (6), of an extraction fan speed (30) and a supply fan speed (40) as a function of measurement data of at least one environmental parameter and therefore at least as a function of measurement data of at least one pollution rate, so as to modulate an extraction rate of stale air in the extraction path (3) and a supply rate of fresh air in the supply path (4) at least as a function of at least one pollution rate; the controlled ventilation process comprising selecting one confined space model from several confined space models, in which for each of the several models are associated instructions for the control unit (6) regarding the speeds of the exhaust fan (30) and the supply fan (40) and / or the extraction and supply flow rates, so that the control unit applies the instructions of the confined space model selected during the control and modulation step.

2. A controlled and modulated ventilation method according to claim 1, wherein at least one environmental parameter also includes an oxygen level, so that continuous measurement of the oxygen level is implemented inside the confined space (2), so that the control and modulation of the speed of the exhaust fan (30) and the speed of the supply fan (40) are carried out at least as a function of at least one pollution level and the oxygen level.

3. Controlled and modulated ventilation method according to claim 1 or 2, wherein at least one environmental parameter also includes an explosive flammability limit, so that continuous measurement of the explosive flammability limit is implemented inside the confined space (2), so that the control and modulation of the speed of the exhaust fan (30) and the speed of the supply fan (40) are carried out at least as a function of at least one pollution level and the explosive flammability limit.

4. Controlled and modulated ventilation method according to any one of the preceding claims, wherein at least one environmental parameter also includes a hydrogen sulfide level, so that continuous measurement of the hydrogen sulfide level is implemented inside the confined space (2), so that the control and modulation of the speed of the exhaust fan (30) and the speed of the supply fan (40) are carried out at least as a function of at least one pollution level and the hydrogen sulfide level.

5. A method of controlled and modulated ventilation according to any one of the preceding claims, wherein at least one environmental parameter also includes a carbon monoxide level, such that continuous measurement of the carbon monoxide level inside the confined space (2) is implemented, so that the fan speed can be controlled and modulated extraction (30) and blower fan speed (40) are carried out at least according to at least one pollution rate and carbon monoxide rate.

6. Controlled and modulated ventilation method according to any one of the preceding claims, wherein at least one environmental parameter also includes an indoor temperature, so that continuous measurement of the indoor temperature is implemented inside the confined space (2), so that the control and modulation of the speed of the exhaust fan (30) and the speed of the supply fan (40) are carried out at least as a function of at least one pollution rate and the indoor temperature.

7. Controlled and modulated ventilation method according to any one of the preceding claims, wherein at least one pollutant comprises a chemical pollutant, selected from volatile organic compounds, volatile halogenated organic compounds, aldehydes, ammonia and mercaptans.

8. Controlled and modulated ventilation method according to any one of the preceding claims, wherein at least one pollutant comprises a radioactive pollutant or a biological pollutant or an inorganic pollutant.

9. A controlled and modulated ventilation method according to any one of the preceding claims, comprising issuing an alert when at least one environmental parameter exceeds a predefined associated alert threshold.

10. A controlled and modulated ventilation method according to any one of the preceding claims, comprising communicating, at given time intervals, to an operator the measurement of at least one environmental parameter.

11. Controlled and modulated ventilation method according to any one of the preceding claims, comprising, downstream of the extraction fan (30), filtration of the stale air extracted in the extraction path (3), before discharge to the outside (EXT).

12. Controlled and modulated ventilation method according to claim 11, wherein the filtration of the stale air is carried out through at least one filter medium (71) in communication with a filtration fan (70) which draws the stale air through the at least one filter medium (71) to expel it to the outside (EXT).

13. Controlled and modulated ventilation method according to claim 12, wherein the control / command unit (6) controls and modulates a speed of the filtration fan (70) so that the air flow rate at the outlet of the filtration fan (70) is equivalent to the extraction flow rate of the stale air in the extraction path (3).

14. Controlled and modulated ventilation method according to claim 12 or 13, wherein at least one upstream sensor (72) and at least one downstream sensor (73) are disposed respectively upstream and downstream of at least one filter medium (71) and measure respectively an upstream pollution rate and a downstream pollution rate corresponding to a concentration of at least one pollutant upstream and downstream of at least one filter medium (71), and wherein the control unit (6) receives measurement data of the upstream pollution rate and the downstream pollution rate from at least one upstream sensor (72) and at least one downstream sensor (73).

15. Controlled and modulated ventilation method according to claim 14, wherein the control unit (6) activates an alert when the downstream pollution level exceeds a critical concentration threshold and / or when a difference between the upstream pollution level and the downstream pollution level is less than a minimum filtration threshold.

16. Controlled and modulated ventilation method according to any one of claims 12 to 15, wherein at least one saturation sensor (74) measures a saturation rate of at least one filter medium (71), and wherein the control / command unit (6) receives measurement data of the saturation rate of at least one filter medium (71) from at least one saturation sensor (74).

17. Controlled and modulated ventilation method according to claim 16, wherein the control / command unit (6) activates an alert when the saturation rate of at least one filter medium (71) exceeds a critical saturation threshold.

18. A controlled and modulated ventilation method according to any one of claims 12 to 17, wherein at least one temperature probe (75) is disposed on or near at least one filter medium (71) in order to measure a temperature of at least one filter medium (71), and wherein the control unit (6) receives temperature measurement data from at least one filter medium (71) from the temperature probe (75).

19. Controlled and modulated ventilation method according to claim 18, wherein the control unit (6) drives the filtration fan (70) according to a given ventilation setpoint when the temperature of at least one filter medium (71) exceeds a critical temperature threshold.

20. Controlled and modulated ventilation method according to any one of claims 12 to 19, wherein an upstream controlled valve (76) and a downstream controlled valve (77) are disposed respectively upstream and downstream of at least one filter medium (71), and wherein the control / command unit (6) is connected to the upstream controlled valve (76) and the downstream controlled valve (77) and commands their closures in the event of a stop of the exhaust fan (30).

21. A controlled and modulated ventilation method according to any one of the preceding claims, wherein at least two successive phases are provided, comprising: - a start-up phase in which the speed of the exhaust fan (30) and the speed of the supply fan (40) are controlled to be respectively at a maximum speed of the exhaust fan (30) and at a maximum speed of the supply fan (40), until at least one environmental parameter is within a predefined safe range; and - a working phase in which the speed of the exhaust fan (30) and the speed of the supply fan (40) are controlled and modulated in real time according to at least one environmental parameter.

22. Controlled and modulated ventilation method according to any one of the preceding claims, comprising heating fresh air before it is blown into the confined space (2).

23. Controlled and modulated ventilation method according to claim 22, wherein heating is provided by a heating system (41) placed on the supply path (4) to heat the fresh air, and a non-return valve (42) is placed on the supply path (4), between the confined space (2) and the heating system (41).

24. A controlled and modulated ventilation method according to claim 22 or 23, comprising a measurement of an internal temperature at the interior of the confined space (2), and control of the fresh air heating so that the interior temperature remains within a predefined temperature range.

25. A controlled and modulated ventilation method according to claim 24, comprising a measurement of an outside temperature, which corresponds to the temperature of the fresh air before heating, and in which the control of the heating of the fresh air is operated as a function of the indoor temperature and the outdoor temperature.

26. Controlled and modulated ventilation method according to claim 24 or 25, wherein the control of the heating of the fresh air is operated according to measurement data of at least one pollution rate.

27. ​​A controlled and modulated ventilation method according to any one of the preceding claims, wherein the installation of the two airflow paths (3, 4) comprises a sealed and temporary mounting of a connecting piece (10) on an access hatch (20) provided on the confined space (2), said connecting piece (10) having two passages for the two airflow paths (3,

28. Controlled and modulated ventilation method according to any one of the preceding claims, wherein the extraction of stale air present in the confined space (2) by the extraction fan (30) is carried out with an extraction air flow rate of between 500 and 15000 m3 per hour.

29. A method of controlled and modulated ventilation according to any one of the preceding claims, wherein the measuring assembly (5) comprises at least one portable measuring device (58) which is in radio communication with the control / command unit (6), said portable measuring device (58) incorporating one or more sensors configured for measuring at least one environmental parameter comprising at least one pollution level.

30. A method of controlled and modulated ventilation according to any one of the preceding claims, wherein the measuring assembly (5) comprises at least one fixed measuring device (57) which is in wired communication with the control unit (6) and which comprises a measuring chamber (570) which is in fluidic communication with the confined space (2) or with the extraction path (3), and which incorporates one or more sensors (51, 52, 53, 54, 55) for a measurement of at least one environmental parameter including at least one pollution rate.

31. Controlled and modulated ventilation method according to claims 21 and 30, wherein the measurement of at least one environmental parameter is implemented by the fixed measuring device (57) at least during the start-up phase.

32. Controlled and modulated ventilation method according to claim 30 or 31, wherein the fixed measuring device (57) includes a distributor (571) upstream of the measuring chamber (570), this distributor (571) having a first inlet (572) in communication with the confined space (2) or with the extraction path (3), and a second inlet (573) in communication with the outside (EXT), so as to be able to put the measuring chamber (570) in communication either with the confined space (2) or with the extraction path (3), or with the outside (EXT).

33. A method of controlled and modulated ventilation according to any one of the preceding claims, comprising a transmission, by the control / command unit (6) and to a remote server (61), of usage data including at least measurement data of at least one environmental parameter and ventilation data including data relating to the speeds of the exhaust fan (30) and the supply fan (40) and / or data relating to the extraction and supply flow rates, for storage and history recording on this remote server of this usage data.

34. Controlled and modulated ventilation process according to claim 33, comprising an issue of an activity report (62) at the end of the controlled and modulated ventilation process, including at least the usage data.

35. Controlled and modulated ventilation method according to any one of the preceding claims, wherein for each of the several models are associated recommendations regarding the locations of the two air circulation paths (3, 4).

36. A method of controlled and modulated ventilation according to any one of the preceding claims, wherein the confined space (2) is a fuel tank, and for example a fuel tank of an aircraft.

37. Controlled and modulated ventilation device (1) for a confined space (2) exposed to at least one pollutant, comprising: - two air circulation paths (3, 4) including an extraction path (3) on which at least one extraction fan (30) is provided and a supply path (4) on which at least one supply fan (40) is provided; - a measuring assembly (5) equipped with at least one sensor (51; 52; 53; 54; 55) configured for continuous measurement of at least one environmental parameter representative of the indoor environment of the confined space (2), the at least one environmental parameter comprising at least one pollution level corresponding to a concentration of at least one pollutant;and - a control / command unit (6) in connection with the measuring assembly (5), the extraction fan (30) and the supply fan (40), said control / command unit (6) being programmed to control and modulate in real time a speed of the extraction fan (30) and a speed of the supply fan (40) as a function of measurement data of at least one environmental parameter, and therefore at least as a function of measurement data of at least one pollution rate;said controlled and modulated ventilation device (1) comprising a means for selecting a confined space model from among several confined space models, in which for each of the several models are associated instructions for the control unit (6) regarding the speeds of the exhaust fan (30) and the supply fan (40) and / or the exhaust and supply flow rates, so that the control unit applies the instructions of the selected confined space model.

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