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

Abstract

Method for controlled and modulated ventilation of a confined space (2) exposed to at least one pollutant, comprising: - setting up an extraction path (3) on which an extraction fan (30) is provided and a blowing path (4) on which a blowing fan (40) is provided; - continuous measurement of at least one environmental parameter representative of the interior environment of the confined space, comprising at least one pollution level; - communication of measurement data of the at least one environmental parameter to a control / command unit (6); - real-time control and modulation of the fan speeds as a function of the measurement data, so as to modulate an extraction flow rate of stale air in the extraction path and a blowing flow rate of fresh air in the blowing path at least as a function of 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 method for controlled and modulated ventilation of 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 inside which human intervention is planned, with the aim of temporarily ventilating this confined space for the duration of the intervention in order to depollute and ventilate the interior of the confined space to promote a healthy environment and in compliance with the requirements of the standard in force.

[0003] The invention finds a preferred, and non-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 scope of the present invention, such as, for example and without limitation, closed rooms such as clean rooms or laboratory rooms, industrial workshops (paint shops, maintenance workshops, etc.), and maritime or road transport containers. Prior art

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

[0005] However, such a solution has numerous 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 quality of the air inside the tank. Summary of the invention

[0006] The invention aims to resolve all or part of the aforementioned drawbacks by proposing a controlled and modulated ventilation method which ensures pollution control to provide increased safety.

[0007] Another aim of the invention is to reduce the decontamination treatment time, in order to allow faster human intervention, and in particular to allow a treatment time of 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] For these purposes, the invention proposes a controlled and modulated ventilation method for controlled and modulated ventilation of a confined space exposed to at least one pollutant, comprising at least the following steps: - installation of two air circulation paths between the interior of the confined space and the exterior, comprising an extraction path on which at least one extraction fan is provided and a blowing path on which at least one blowing fan is provided; - activation of the extraction fan to extract stale air present in the confined space into the extraction path and discharge it to the outside; - activation of the blowing fan to draw fresh air from outside into the blowing path and blow it inside the confined space (and for example in a privileged area of ​​this confined space, close to an operator working inside this confined space); - continuous measurement, by a measuring system, of at least one environmental parameter representative of the interior environment of the confined space, the at least one environmental parameter comprising at least one pollution rate corresponding to a concentration of the at least one pollutant; - real-time communication of measurement data of at least one environmental parameter from the measuring assembly to a control / command unit which is connected to the extraction fan and the blower fan; - real-time control and modulation, by the control / command unit, of an extraction fan speed and a blowing fan speed as a function of the measurement data of the at least one environmental parameter and therefore at least as a function of measurement data of the at least one pollution rate, so as to modulate a stale air extraction flow rate in the extraction path and a fresh air blowing flow rate in the blowing path at least as a function of the at least one pollution rate.

[0010] Thus, the invention proposes to use both the extraction fan to suck in the polluted stale air, and the blowing fan to force the introduction of fresh air and consequently improve the renewal of the air. Furthermore, it is also proposed to modulate the extraction flow rate of the stale air as a function at least of the rate of pollution, and also to modulate the fresh air blowing flow rate. Thus, the higher the pollution rate, the higher the extraction flow rate and the blowing flow rate will be, and conversely, the lower the pollution rate, the lower the extraction flow rate and the blowing flow rate will be; which is advantageous for adapting the extraction and blowing performance in real time according to the pollution rate and thus increasing safety. In other words, the extraction flow rate and the blowing flow rate will be modulated / adapted according to the evolution of the concentration of at least one pollutant in the confined space; with therefore a control of the pollution rate which constitutes a monitoring of the risk to which the worker is exposed.

[0011] This solution therefore also makes it possible to treat the confined space more quickly, generally in less than two hours for a volume of 100 m3 maximum, by ensuring a high extraction flow rate and a high blowing flow rate at the start of the treatment while the pollution level is high, then by reducing this extraction flow rate and this blowing flow rate as the pollution level drops, to ultimately maintain a low pollution level in the confined space and an optimal air renewal rate.

[0012] In other words, the method ensures controlled ventilation in real time by acting on the extraction fan and the blowing fan, since the ventilation is controlled by real-time monitoring of the concentration of the at least one pollutant, and also ensures modulated ventilation, since the extraction flow rate and the blowing flow rate are modulated / adjusted as a function of the concentration of the at least one pollutant.

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

[0014] In this way, the oxygen level is also taken into consideration, to adapt the extraction and blowing in order 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 route.

[0015] According to another characteristic, the at least one environmental parameter also comprises an explosive flammability limit, so that a continuous measurement of the explosive flammability limit inside the confined space is implemented, so that the control and modulation of the speed of the extraction fan and the speed of the blowing fan are carried out at least as a function of at least one pollution rate 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 path.

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

[0018] Thus, the hydrogen sulfide (H2S) level is also taken into consideration to renew the air inside the confined space. This gas, hydrogen sulfide, can be measured using a specifically adapted sensor. This approach makes it possible to adjust the ventilation precisely in response to the hydrogen sulfide concentrations, thus 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 path.

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

[0020] Thus, the carbon monoxide (CO) level is therefore taken into consideration to renew the air inside the confined space. This gas, carbon monoxide, can be measured using a specifically adapted sensor. This approach makes it possible to adjust the ventilation precisely in response to the carbon monoxide concentrations, thus 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 path.

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

[0022] In this way, the interior temperature is also taken into account to renew the air inside the confined space; because the interior temperature may depend on safety parameters, such as for example a release rate of a pollutant, such as volatile organic compounds or certain toxic compounds. 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 interior temperature can be measured inside the confined space and / or outside the confined space at the extraction path.

[0023] Furthermore, another advantage is to be able to control the speed of the blowing fan to cool the confined space, in other words to reduce the interior temperature. With regard to this cooling, it is therefore possible to regulate the speed of the blowing fan, while allowing temperature adjustments within the limits of compliance with the aforementioned safety parameters, such as being below an evaporation temperature of the 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 chemical pollutant monitored could advantageously be one or more volatile organic compounds from the fuel.

[0026] Generally, pollutant measurements must be adapted to the targeted pollutant, since different detection techniques can be used. This adaptation of the measurements offers the possibility of implementing controlled and modulated ventilation, thus ensuring a targeted and effective approach depending on the specific pollutant.

[0027] Alternatively, the at least one pollutant comprises a radioactive pollutant or a biological pollutant or an inorganic pollutant.

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

[0029] In a particular embodiment, the method comprises issuing an alert when the 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 operator 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 to a mobile device, such as a telephone, an audible signal, a text message, an email or a notification in a mobile application.

[0032] Advantageously, the method comprises a communication, at a given time interval, to an operator of the measurement of at least one environmental parameter.

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

[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 telephone.

[0035] In a particular embodiment, the method comprises, downstream of the extraction fan, 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 discharged outside, in order to purify it before being discharged 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 sucks the stale air through the at least one filter medium to discharge it outside.

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

[0039] The use of this extraction fan advantageously makes it possible to compensate for the pressure drop across the at least one filter medium, thus ensuring that the efficiency of the filtration fan is maintained without degradation. This extraction fan thus contributes to optimizing the system to ensure constant performance.

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

[0041] Thus, the filtration fan and the extraction fan are controlled by the control / command unit so that these two fans operate in a synchronized manner with the same flow rates (and for example at the same engine speed if the fans are equivalent) to ensure proper operation of the system. This synchronization ensures consistency in the air flow and contributes to the overall efficiency of the system.

[0042] According to one variant, the at least one filtering 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 arranged respectively upstream and downstream of the at least one filtering medium and respectively measure an upstream pollution rate and a downstream pollution rate corresponding to a concentration of the at least one pollutant upstream and downstream of the at least one filtering medium, and furthermore the control / command unit receives measurement data of the upstream pollution rate and the downstream pollution rate from the at least one upstream sensor and the at least one downstream sensor.

[0045] Thus, the control / command unit monitors, and possibly records, the measurement data of the upstream pollution rate and the downstream pollution rate, thus making it possible to establish a pollution balance and to monitor the levels of contamination by polluting the filter medium. Thanks to this data, it is possible to predict and detect any exceedance or saturation of the filter medium, which makes it possible to take appropriate corrective measures to ensure efficient operation of the filtration.

[0046] According to one possibility, a carbon monoxide sensor can be provided at the level of the 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 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.

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

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

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

[0051] Thus, the control / command unit monitors, and possibly records, the measurement data of the saturation rate of the at least one filtering medium (for example as a percentage or as a quantity of pollutant trapped in the filtering medium), thus making it possible to establish a filling or saturation level of this at least one filtering medium, and therefore to estimate the remaining capacity of this at least one filtering medium, thus providing a precise evaluation of the available trapping space and in real time.

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

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

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

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

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

[0057] Thus, the filtration fan applies the ventilation setpoint in order to ensure good ventilation of the filter medium, for efficient dissipation of the heat generated by the overheating filter medium. For example, the ventilation setpoint may correspond to a nominal speed of the filtration fan to dissipate this heat.

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

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

[0060] In an advantageous embodiment, the method 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 respectively at a maximum exhaust fan speed and a maximum supply fan speed, until the 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 extraction and blowing fans operate at their maximum speeds to promote rapid air renewal, before entering the working phase where the extraction and blowing fans operate at reduced speeds, for the comfort of the operator, but always 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 complete 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 the maximum speed of the extraction fan and the maximum speed of the blowing fan respectively.

[0063] The invention also relates to the possibility of having heating of the new air before being blown inside the confined space.

[0064] Such heating makes it possible to have an environment at an acceptable and comfortable ambient interior 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 required. Similarly, the indoor temperature may be adjusted, for example in a range of 18 to 25°C.

[0066] Heating is provided by a heating system placed on the blowing 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 the blowing fan stopping, avoiding any contact with the heating system, and therefore avoiding any risk of fire or explosion.

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

[0069] According to one characteristic, the method comprises 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 carried out as a function of the inside temperature and the outside 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 characteristic, the control of the heating of the fresh air is carried out as a function of the measurement data of the at least one pollution rate.

[0072] Indeed, in the case where the pollutant is sensitive to temperature, as is the case with volatile organic compounds, it is advantageous to take into account the measured pollution rate to avoid any undesirable evaporation of the pollutant, and therefore to adapt the heating in order to avoid an increase in this pollution rate. Furthermore, and as seen previously, the speed of the extraction fan and the speed of the blowing fan are also controlled and modulated according to this pollution rate.

[0073] For example, the evaporation potentially caused by the heated fresh air is monitored by measuring the level of volatile organic compounds, and therefore the heating is adapted according to this measurement. In addition, 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 comprises a sealed and temporary mounting of a connection piece on an access hatch provided on the confined space, said connection piece having two passages for the two air circulation paths.

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

[0076] According to one possibility, the extraction of the stale air present in the confined space by the extraction fan is carried out with an extraction air flow rate of between 500 and 20,000 m3 per hour.

[0077] According to one characteristic, the extraction of the stale air present in the confined space by the extraction fan is carried out with an extraction air flow rate of between 500 and 15,000 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 extraction flow rate required.

[0079] According to one characteristic, the measuring assembly comprises at least one portable measuring device which is in radio communication with the control / command unit, said portable measuring device integrating one or more sensors designed for measuring at least one environmental parameter including at least one pollution rate.

[0080] Such a portable measuring device is advantageous because it can be carried 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 this operator.

[0081] This portable measuring device may for example be a multi-gas detector which 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 comprise a cell for measuring the explosive flammability limit.

[0082] This custom-made portable measuring device operates on battery power and integrates radio communication and real-time monitoring functionalities. Radio communication between the portable measuring device and the control / command unit can take place according to different protocols, such as, for example and without limitation, 3G, 4G, 5G, Bluetooth©, WiFi©, LoRa©, etc.

[0083] According to another characteristic, the measuring assembly comprises at least one fixed measuring device which is in wired communication with the control / command unit and which comprises a measuring chamber which is in fluid communication with the confined space or with the extraction path, and which integrates one or more sensors shaped for measuring the at least one environmental parameter comprising the at least one pollution rate.

[0084] Such a fixed measuring device is advantageous because it allows stable operation due to the wired communication with the control / command 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 path, without an operator having to enter it.

[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 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 to manually enter the measurement variables, such as CO, H2S, VOC, 02 levels and the explosive flammability limit, in case of network problems. This operation can be easily carried out using a direct reading on the portable measuring device and then entered into the control / command unit manually. This is particularly useful in the case of a portable measuring device not equipped with a network connection or in a network outage situation.

[0087] This fixed measuring device may comprise an air pump for pumping the stale air towards the measuring chamber.

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

[0089] Thus, the distributor is used to sample clean air from outside at regular intervals, instead of stale air. By sampling this clean air which is directed into the measuring chamber, the life of the sensors is increased, optimal sensitivity of these sensors is maintained (thus avoiding any saturation of the detection cell) and their optimal response times are maintained. Indeed, by sampling clean air at regular intervals, the exposure of the sensors to pollutants is reduced, which helps to extend their operational lives. In addition, 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 from the chamber thus plays an important role in increasing both the lifespan of the sensors and their sensitivity. By doing so, not only is the performance of the sensors preserved over the long term, but it also makes it possible to detect any potential leaks in the equipment. In addition, this measurement offers the possibility of monitoring the quality of the outside air in real time, thus making it possible to check the quality of the fresh air blown into 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 the at least one environmental parameter is implemented by the fixed measuring device at least during the start-up phase.

[0092] Indeed, at start-up, it is recommended, or even obligatory, that no one accesses the interior of the confined space, and in this case the measurement of the at least one environmental parameter is carried out by the fixed measuring device, in its measuring chamber, to know the at least one pollution rate. In this way, this fixed measuring device makes it possible to know if or when this at least one pollution rate is below a tolerable threshold to allow the entry of an operator into the confined space.

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

[0094] Thus, this historization of these 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 the at least one environmental parameter and the ventilation data, so as, for example, to refine certain parameters to improve the ventilation during a future session.

[0095] Advantageously, the method comprises an edition of an activity report at the end of the controlled and modulated ventilation method, comprising at least the usage data.

[0096] Such an activity report is therefore generated at the end of the activity, i.e. once the controlled and modulated ventilation has stopped. In addition, such an activity report can also be generated at the request of the user or 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 the oxygen level and the explosive flammability limit; and - ventilation data used and - results obtained.

[0097] This activity report therefore makes it possible to evaluate the effectiveness of the controlled and modulated ventilation after the fact and to verify compliance with safety standards. The activity report may also contain additional data on the temperature, pressure and humidity conditions, as well as on the air renewal rates and the air speed around the operator. This additional data is advantageous for evaluating the overall environment in which the ventilation operation took place.

[0098] According to one characteristic, the method comprises a selection of a confined space model from among several confined space models, in which for each of the several models are associated instructions for the control / command unit as to the speeds of the extraction fan and the blowing fan and / or the extraction and blowing flow rates, so that the control / command 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 of the blower fan and / or for modulating the extraction and blower flow rates, depending 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 the space constraints and the areas that are difficult to ventilate. Such instructions, specific to each confined space model, form in a way recipes which aim to ensure adequate air circulation and to guarantee an optimal and personalized ventilation level to maintain a safe environment inside the confined space.

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

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

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

[0103] In a preferred 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 blowing path on which at least one blowing fan is provided; - a measuring assembly provided with at least one sensor designed for continuous measurement of at least one environmental parameter representative of the interior environment of the confined space, the at least one environmental parameter comprising at least one pollution rate corresponding to a concentration of the at least one pollutant; and - a control / command unit in connection with the measuring assembly, the extraction fan and the blowing fan, said control / command unit being programmed to control and modulate in real time a speed of the extraction fan and a speed of the blowing 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 device thus makes it possible to implement the method described above. This controlled and modulated ventilation device is in particular adapted to meet the “ATEX” certification specific to explosive atmospheres. Depending on the use, this controlled and modulated ventilation device can also be offered in a version not compliant with the “ATEX” certification in order to meet the diverse needs of users. Brief description of the drawings

[0106] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:

[0107] [Fig.l] is a schematic view of a controlled and modulated ventilation device for implementing a method of ventilating 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.l], a controlled and modulated ventilation device 1 adapted for implementing a controlled and modulated ventilation method 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 makes it possible to extract stale air present in the confined space 2 into the extraction path 3 and to reject it to the outside EXT; and - a blowing path 4 on which a blowing fan 40 is provided, so that activation of the blowing fan 40 makes it possible to suck fresh air from the outside EXT into the blowing path 4 and blow it inside the confined space 2.

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

[0112] The controlled and modulated ventilation device 1 comprises, 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 the stale air through this filter medium 71; and - a filtration fan 70, in communication with the filtering medium 71 to suck the stale air through this filtering medium before discharging it to the outside EXT.

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

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

[0116] The filtration system 7 comprises an upstream controlled valve 76 and a downstream controlled valve 77 which are arranged respectively upstream and downstream of the filter medium 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 comprise a carbon monoxide sensor for measuring a carbon monoxide level at the filter medium 71, in order to be able to determine the start of a fire in the filter medium 71.

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

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

[0120] More precisely, the measuring assembly 5 comprises at least one sensor 51 shaped for continuous measurement of a pollution rate corresponding to a concentration of the at least one pollutant, this pollution rate 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 shaped for measure the respective pollution rates of the different pollutants. The at least one pollutant comprises a chemical pollutant, chosen from volatile organic compounds, volatile halogenated organic compounds, aldehydes, ammonia and mercaptans. It should be noted that the measurement can be carried out at the level of the confined space 2 and / or at the level of the extraction path 3.

[0121] The measuring assembly 5 also comprises: - a sensor 52 configured for continuous measurement of an oxygen level inside the confined space 2, considered as an environmental parameter; - a sensor 53 designed 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 interior temperature inside the confined space 2, considered as an environmental parameter.

[0122] The measuring assembly 5 may also comprise: - 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 measuring a continuous carbon monoxide level inside the confined space 2, considered as an environmental parameter.

[0123] In the example illustrated, these sensors 51-56 are part of a fixed measuring device 57. These sensors 51-56 can carry out 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 comprise a measuring chamber 570 which is in fluid communication with the confined space 2 or with the extraction path 3 and which integrates one or more sensors shaped for measuring all or part of the environmental parameters described above. In other words, the measuring chamber 570 may integrate all or part of the sensors 51-56 described above. In the example illustrated in [Fig. 2], the measuring chamber 570 is in fluid communication with the extraction path 3.

[0125] This fixed measuring device 57 comprises 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 exterior 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 exterior EXT, as well as an outlet in communication with the measuring chamber 570.

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

[0127] When the distributor 571 connects its first inlet 572 to its outlet, and therefore puts the measuring chamber 570 in communication with the extraction path 3 (or alternatively with the confined space 2), then the measurements can be made by means of the sensor(s) 51-56 present in the measuring chamber 570. When the distributor 571 connects its second inlet 573 to its outlet, and therefore puts the measuring chamber 570 in communication with the exterior EXT, then clean air enters the measuring chamber 570, thus making it possible to avoid saturation of the sensor(s) 51-56 present in the measuring chamber 570, which reduces their lifetimes, their sensitivities and their response times.

[0128] The measuring assembly 5 may also comprise a portable measuring device 58 capable of 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 radiocommunication module 59, for example in 3G, 4G, 5G, Bluetooth©, WiFi©, LoRa©, etc.

[0129] The controlled and modulated ventilation device 1 comprises a control / command unit 6 (for example of the automaton or processor type) in connection with the measuring assembly 5 (and therefore with its various sensors 51-56 as well as the sensors of the portable measuring device 58). More precisely, the control / command unit 6 is in wired connection with the fixed measuring device 57, and if necessary it is in radio communication with the portable measuring device 58.

[0130] Thus, the measurement data of at least one environmental parameter, and more precisely 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 / command unit 6 is also connected to the extraction fan 30, the blowing fan 40 and the filtration fan 70, so as to control their operations (inactive mode and active mode) and in particular to control the speeds of these three fans 30, 40, 70.

[0132] This control / command unit 6 is programmed to control and modulate in real time the speed of the extraction fan 30 and the speed of the blowing 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 coming from the sensor 51 (or from the sensors 51 if several pollution rates pollution are measured), so as to modulate a flow rate of extraction of stale air in the extraction path 3 and a flow rate of blowing of fresh air in the blowing path 4 at least as a function of the at least one pollution rate.

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

[0134] This real-time control and modulation of the speed of the extraction fan 30 and the speed of the blowing fan 40 by the control / command unit 6 are thus carried out at least as a function of the pollution rate (or pollution rates), and they can also be carried out as a function of: - the oxygen level measured by the sensor 52 and / or by a dedicated sensor which is integrated into the portable measuring device 58; and / or - the explosive flammability limit measured by the sensor 53 and / or by a dedicated sensor which is integrated into the portable measuring device 58; and / or - the interior temperature measured by the sensor 54 and / or by a dedicated sensor which is integrated into the portable measuring device 58; and / or - the hydrogen sulfide rate measured by the sensor 55 and / or by a dedicated sensor which is integrated into the portable measuring device 58; and / or - the carbon monoxide level measured by the 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 extraction fan 30 and the speed of the blowing fan 40 are controlled (or adjusted) to be respectively at a maximum speed of the extraction fan 30 and at a maximum speed of the blowing fan 40, until the at least one environmental parameter is within a predefined safe range, and more particularly until the at least one pollution rate is below a low threshold which complies with the safety standards in force.

[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] Beforehand, it is possible to select a confined space model from several confined space models. In a preferred application, the 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 emissions which may not be the same either 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 blowing fan 40 can be established according to the selected model, to correspond specifically to the confined space 2. Furthermore, for each of the several models of confined space, recommendations can be associated as to the locations of the two circulation paths 3, 4.

[0139] Following the start-up phase, the control / command unit 6 is configured to implement a work 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 as a function of the at least one environmental parameter, and in particular as a function of the pollution rate (or pollution rates) and any other aforementioned environmental parameters.

[0140] Thus, in the work phase, the extraction flow rate of the stale air in the extraction path 3 and the blowing flow rate of the fresh air in the blowing path 4 are controlled and modulated dynamically, in real time, in response to the measurement data from the measuring assembly, and in particular from the different sensors 51-56, as well as from the sensors of the portable measuring device 58 if the operator is equipped with one when coming inside the confined space 2, and based on the flow rate measurements made by the flow meters placed in the blowing path 4 and in the extraction path 3; so as to ensure the maintenance of a low concentration of the 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 speeds of the fans 30, 40 makes it possible to adjust the extraction and blowing flow rates precisely, preferably remaining below the maximum speeds, because high flow rates could further stimulate the liquid sources of pollutant (such as kerosene which is likely to degas and therefore release pollutants such as volatile organic compounds), hence the interest in adapting these extraction and blowing 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 interior temperature is advantageous, because an increase in the interior temperature beyond a certain temperature threshold could lead to precisely 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, because this temperature threshold can depend on the volume and the pollutant emission sources reported for each of the confined space models.

[0144] The blowing fan 40 is used to blow fresh air, and thus participate in the extraction of stale air and the decontamination of the air inside the confined space 2. It also makes it possible to create a pleasant and refreshing air current in the confined space 2 for the comfort of the operator. However, during winter or cold periods, the blowing 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 interior temperature within a predefined temperature range.

[0145] Also, the control / command unit 6 is connected to this heating system 41 in order to control it to control the heating of the fresh air blown by the blowing fan 40. An outside temperature sensor 43 may be provided which is located outside EXT to measure an outside temperature, which therefore corresponds to the temperature of the fresh air before heating. The control / command unit 6 is thus connected to this outside temperature sensor 43 as well as to the sensor 54 which continuously measures the inside temperature inside the confined space 2, and the control / command unit 6 operates the control of the heating of the fresh air as a function of the inside temperature and the outside temperature.

[0146] This heating control can also take into account the measurement data of the at least one pollution rate, since the release of the pollutant can 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 / command unit 6 is connected to the filtration system 7, and more precisely 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 / command unit 6 controls and modulates the speed of the filtration fan 70 so that the flow rate of the air leaving 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 to the downstream sensor 73 to recover the 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 recover the measurement data of the saturation rate of the filter medium 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 recover the measurement data of the temperature of the filter medium 71, and the control / command unit 6 controls the filtration fan 70 according to a given ventilation setpoint when the temperature of the filter medium 71 exceeds a critical temperature threshold.

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

[0152] During the work phase, the control / command unit 6 is configured to issue an alert when the at least one environmental parameter exceeds a predefined associated alert threshold, and in particular: - the pollution rate (or one of the pollution rates) 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 level exceeds a carbon monoxide alert threshold.

[0153] During the work phase, the control / command unit 6 is configured to communicate data on a mobile terminal 60 (for example a telephone, a tablet, a personal digital assistant or “Personal Digital Assistant” in English) carried by the operator who is inside the confined space 2.

[0154] The control / command unit 6 communicates in particular, at a given time interval, to the operator on his mobile terminal 60 the measurement of at least one environmental parameter, or even the measurements of all the 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 his mobile terminal 60, in order to inform him of the risk, and possibly inform him that he must leave the confined space 2 and / or equip himself with a protective device (such as for example 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 comprising: - at least the measurement data of at least one environmental parameter (or even the measurement data of 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 the extraction and supply flow rates; for storage and historization on this remote server 61 of this usage data.

[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 edited and includes at least the usage data. Thus, the usage data collected and linked to the intervention will be used to establish this activity report 62 in an automated manner, therefore including all the data relating to the intervention, including temporal and spatial data, volumes treated, nature of the pollutants, anomalies, etc.

Claims

Claims

1. A 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: - setting up two air circulation paths (3, 4) between the inside of the confined space (2) and the outside (EXT), comprising an extraction path (3) on which at least one extraction fan (30) is provided and a blowing path (4) on which at least one blowing fan (40) is provided; - activating the extraction fan (30) to extract stale air present in the confined space (2) into the extraction path (3) and discharge it to the outside (EXT); - activating the blowing fan (40) to suck fresh air from the outside (EXT) into the blowing path (4) and blow it into the confined space (2);- continuous measurement, by a measuring assembly (5), of at least one environmental parameter representative of the interior environment of the confined space (2), the at least one environmental parameter comprising at least one pollution rate corresponding to a concentration of the at least one pollutant; - real-time communication of measurement data of the at least one environmental parameter, including at least measurement data of the at least one pollution rate, from the measuring assembly (5) to a control / command unit (6) which is connected to the extraction fan (30) and the blowing fan (40);- real-time control and modulation, by the control / command unit (6), of a speed of the extraction fan (30) and a speed of the blowing fan (40) as a function of the measurement data of the at least one environmental parameter and therefore at least as a function of the measurement data of the at least one pollution rate, so as to modulate a flow rate for extracting stale air in the extraction path (3) and a flow rate for blowing fresh air in the blowing path (4) at least as a function of the at least one pollution rate.;

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

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

4. A method of controlled and modulated ventilation according to any one of the preceding claims, in which the at least one environmental parameter also comprises a hydrogen sulfide level, such that a continuous measurement of the hydrogen sulfide level inside the confined space (2) is implemented, so that the control and modulation of the speed of the extraction fan (30) and the speed of the blowing fan (40) are carried out at least as a function of the 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, in which the at least one environmental parameter also comprises a carbon monoxide level, such that a continuous measurement of the carbon monoxide level inside the confined space (2) is implemented, so that the control and modulation of the speed of the extraction fan (30) and the speed of the blowing fan (40) are carried out at least as a function of the at least one pollution level and the carbon monoxide level.

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

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

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

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

10. Method of controlled and modulated ventilation according to any one of the preceding claims, comprising communication, at a given time interval, to an operator of the measurement of at least one environmental parameter.

11. Method of controlled and modulated ventilation 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, in which the filtration of the stale air is carried out through at least one filter medium (71) in communication with a filtration fan (70) which sucks the stale air through the at least one filter medium (71) to discharge it outside (EXT).

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

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

15. Controlled and modulated ventilation method according to claim 14, in which 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.

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

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

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

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

20. A method of controlled and modulated ventilation according to any one of claims 12 to 19, in which a controlled valve upstream (76) and a downstream controlled valve (77) are arranged respectively upstream and downstream of the at least one filter medium (71), and in which the control / command unit (6) is connected to the upstream controlled valve (76) and to the downstream controlled valve (77) and controls their closing in the event of the extraction fan (30) stopping.

21. A method of controlled and modulated ventilation 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 extraction fan (30) and the speed of the blowing fan (40) are controlled to be respectively at a maximum speed of the extraction fan (30) and at a maximum speed of the blowing fan (40), until the at least one environmental parameter is within a predefined safe range; and - a working phase in which the speed of the extraction fan (30) and the speed of the blowing fan (40) are controlled and modulated in real time as a function of the at least one environmental parameter.

22. A method of controlled and modulated ventilation according to any one of the preceding claims, comprising heating the fresh air before being blown inside the confined space (2).

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

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

25. A method of controlled and modulated ventilation 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 carried out as a function of the inside temperature and the outside temperature.

26. Method of controlled and modulated ventilation according to claim 24 or 25, in which the control of the heating of the fresh air is carried out as a function of the measurement data of the at least one pollution rate.

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

28. A method of controlled and modulated ventilation 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. Method for controlled and modulated ventilation according to any one of the preceding claims, in which 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) integrating one or more sensors configured for a measurement of the at least one environmental parameter comprising the at least one pollution rate.

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

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

32. A method of controlled and modulated ventilation according to claim 30 or 31, wherein the fixed measuring device (57) comprises 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 exterior (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 exterior (EXT).

33. Method for 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 comprising at least the measurement data of at least one environmental parameter and ventilation data comprising data relating to the speeds of the extraction fan (30) and the blowing fan (40) and / or data relating to the extraction and blowing flow rates, for storage and logging on this remote server of this usage data.

34. Method of controlled and modulated ventilation according to claim 33, comprising an edition of an activity report (62) at the end of the method of controlled and modulated ventilation, comprising at least the usage data.

35. A method of controlled and modulated ventilation according to any one of the preceding claims, comprising a selection of a confined space model from among several confined space models, in which for each of the several models there are associated setpoints for the control / command unit (6) as to the speeds of the extraction fan (30) and the blowing fan (40) and / or the extraction and blowing flow rates, so that the control / command unit applies the setpoints of the selected confined space model during the control and modulation step.

36. Method of controlled and modulated ventilation according to claim 35, in which for each of the several models there are associated recommendations as to the locations of the two air circulation paths (3, 4).

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

38. Controlled and modulated ventilation device (1) for a confined space (2) exposed to at least one pollutant, comprising: - two air circulation paths (3, 4) comprising an extraction path (3) on which at least one extraction fan (30) is provided and a blowing path (4) on which at least one blowing fan (40) is provided; - a measuring assembly (5) provided with at least one sensor (51; 52; 53; 54; 55) configured for continuous measurement of at least one environmental parameter representative of the interior environment of the confined space (2), the at least one environmental parameter comprising at least one pollution rate corresponding to a concentration of the at least one pollutant; and - a control / command unit (6) in connection with the measuring assembly (5), the extraction fan (30) and the blowing 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 blowing fan (40) as a function of measurement data of the at least one environmental parameter, and therefore at least as a function of measurement data of the at least one pollution rate.

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