FR2831665A1 - Detection and analysis of chemical or biological substances in the atmosphere, locating the geographical extent of the contaminated area and its evolution over time and space - Google Patents

Abstract

Detection (M1) and analysis of chemical or biological substances in the atmosphere comprising communal transport vehicles following regular routes in the area which are monitored fitted with analyzers which continuously and rapidly analyze the air, is new. In M1, the results are transmitted in real time to a central control post (PC) with location and time data. The central control post treats the results so at any moment it has all the useful information on a contamination. The chemical or biological substances in the atmosphere are identified and quantified, locating the geographical extent of the contaminated area. Together with quantitative analysis by geographical vectors of the contamination, this provides all the useful information about a contamination, particularly its nature, concentration, extent and evolution over time and space. The geographical data are obtained from the location devices normally fitted to the vehicles or from an additional location device, preferably GPS. The variations with time and /or gradients of contamination are determined whilst finding the heart of the contamination. The detection and analysis is done using flame spectrophotometry and/or ionization. The gas flow into the detector is lit by a light source emitting rays of wavelengths different from those used for spectrophotometry, to carry out a nephelometri and/or turbidometric detection on the gas flow used. The data from this detection process is used to control the spectrophotometer correctly, and to count the particles present using data from both devices. The detector also includes a measure of fluorescence. Independent claims are also included for a system for carrying out M1, using a network of communal vehicles (for example a railway, underground or bus network) each with means of communicating with the central command post and means of location. Each vehicle carries an analyzer and means of composing digital messages containing each analysis result and transmitting these messages to the central command post. The central command post has means of handling the data received to ensure that at any moment it has all the useful information from the area being monitored. The data is transmitted using hertzian transmitter/receivers and the vehicles can receive orders from the central command post to modify the operation of the analyzer.

Description

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The present invention relates to a method and a device for detecting the presence in the atmosphere of chemical and / or biological substances, for the identification and quantification of these substances, for the location of the geographical extent of the contaminated area. by said substances as well as for the quantitative analysis by geographic sectors of the contamination as well as the evolution in time and space of this contamination.

In general, we know that public authorities are increasingly concerned about air quality and the risks of atmospheric contamination, particularly in urban areas.

Current events show that these risks are always present, whether from accidental contamination, criminal attacks, or even acts committed during a state of war.

To be able to react effectively during an atmospheric contamination, it is necessary to detect it as quickly as possible, identify it, locate it, determine its geographical extent, predict its evolution and this, in a minimum of time so as to take all the necessary measures with the population endangered by this contamination. In particular, security officials will need to be able in a very short time

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 evacuate populations from risk areas and direct them to unexposed areas.

For this purpose, they must be kept informed, at all times, of the evolution of pollution and its evolution so as not to run the risk of directing evacuees to areas that are contaminated or at risk of be contaminated later.

However, at the present time, detection and analysis devices are used which are arranged either at a fixed station or on board vehicles specially equipped for this purpose and which carry out analyzes successively at different points in the zone to be monitored. .

This solution proves satisfactory for the measurement of pollution rate with slow variation and having a low toxicity. However, it is not suitable for substances with high toxicity and rapid spread. Indeed, to be able to intervene effectively during this type of contamination, it would be necessary to have a very high number of fixed or mobile detectors so that this solution can be generalized.

The invention therefore more particularly aims to solve this problem in a relatively simple, effective and at the same time inexpensive.

To this end, the Applicant bases itself on the fact that it already produces portable and autonomous detectors making it possible to carry out the detection and analysis of the ambient air in very short times and this, completely automatically, with digitization of the analysis results.

Likewise, it takes into account the fact that, in urban areas, the areas most sensitive to atmospheric contamination are constantly traversed by regular vehicles.

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 public transport equipped with means of communication so as to exchange information remotely with a central control station.

Given these considerations, the method according to the invention is characterized in that it consists in equipping public transport vehicles carrying out regular lines in the area to be monitored, with analyzers capable of continuously carrying out the detection and the analysis of the air in a very short time and to transmit, in real time, to the central control station, messages comprising the result of the analysis which has just been made, timestamp data as well as geographic data relating to the place where the analysis was carried out, and in that the central station which receives the messages of all the vehicles equipped with analyzers performs an analysis of these results so as to be able to know at all times all the useful information on contamination, in particular the nature, concentration, extent and evolution over time and space.

Advantageously, the method according to the invention will use the locating means normally fitted to the vehicle, or even a reported locating system for example of the GPS ("global positioning system") type so as to be able to indicate in the messages precise information on the vehicle position at the time of analysis.

Preferably, the abovementioned analyzers may consist of devices for analyzing gaseous compositions by flame spectrophotometry, for example of the type described in patent FR No. 98 00761 or FR No. 01 04934 filed in the name of the Applicant. Indeed, these portable and autonomous devices can be easily mounted on vehicles. In addition, they make it possible to carry out analyzes in very short times compatible with the "real time" operation of the system.

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 Of course, these devices must be able to solve both the problems relating to the speed of detection and the speed of movement of the vehicle.

Of course, the invention also relates to a system for implementing the method according to the invention, this system involving: - at least one network of public transport vehicles (for example a railway, metro network , bus) using vehicles each equipped with means of communication with a central control station and locating means, - at least one analysis device mounted on each of the vehicles, this analysis device being designed so as to perform continuous analyzes during the movement of the vehicle, - means for composing digital messages each containing the result of an analysis carried out by an analysis device, vehicle identification data, time stamping data as well as geographic location data of the place in which the analysis was carried out, - means allowing these messages to be sent to the central station by the in intermediary of the aforesaid means of communication, - means making it possible to analyze, in real time, the messages received by the central station originating from the vehicles so as to be able to present at all times to an operator all the useful information occurring in a protected area.

An important advantage of this system is that it makes it possible to determine both variations over time and gradients of contamination and thus, to pinpoint the core of the contamination and assess its evolution over time. .

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An embodiment of the invention will be described below, by way of nonlimiting examples, with reference to the appended drawings in which:
Figure 1 shows a network of public transport vehicles equipped with analysis devices;
Figure 2 is a schematic view of an analysis apparatus which can be mounted on a vehicle and which can operate during the movements of this vehicle in a relative wind at relatively high speed;
FIG. 3 is a block diagram of an analysis apparatus equipping a vehicle, this apparatus being able both to carry out an analysis of the gaseous composition of the air as well as the counting and analysis of particles or aerosols suspended in the air.

As previously mentioned, the method according to the invention necessarily involves a public transport network comprising regular lines crisscrossing the area to be monitored.

Thus, by way of example, FIG. 1 shows the road map of an urban agglomeration crossed by three lines of vehicles Li, L2, L3 (for example buses) on each of which several vehicles can travel at any time. (here VI, V '} - V2, V'2-V3, V'3).

Each of these vehicles carries an analysis device and comprises transmission / reception means making it possible to exchange information with a central PC station.

The analysis device present on each vehicle is designed so as to continuously carry out an analysis and to transmit these results with

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 identification, time stamp, and location of measurement points to the PC central station. Thus, at a given instant, the central station has all the analysis results transmitted in a very short period of time (practically in real time) and covering the area to be monitored.

As a result, the central station can determine the approximate extent and orientation of a contaminated area (represented by hatching). Given the number of vehicles on the lines and the frequency of these vehicles, the information will be constantly refreshed and even supplemented by the fact that the measurement points are never at the same locations.

Thanks to these provisions, it will be possible to determine precisely and without risk of error the measures to be taken to protect the population.

The flame spectrophotometry analysis equipment fitted to vehicles may involve, as shown in FIG. 2, a burner 1 comprising a tubular body 2 delimiting a combustion chamber 3 closed, on one side, by a bottom 4 and, the other side, by a cover 5 having a circular coaxial opening in which is mounted a lens 6. Outside the burner 1 and in the axis of this lens 6, is arranged an optoelectronic cell 7, of a device flame spectrophotometry (a rotary filtering system possibly being interposed between the lens 6 and the cell 7).

The combustion chamber 3 has a lateral exhaust orifice 8 connected to an exhaust circuit 9 provided with a turbine 10 actuated by a motor 11.

The bottom 4 of the burner 1 has a bore in communication with a coaxial mixing nozzle 12 which extends over a fraction of the length of the

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 combustion chamber 3 which communicates, on the one hand, with an inlet pipe for the gas to be analyzed 14 (which crosses the bottom) and, on the other hand, with a hydrogen injection duct 15 which crosses radially the longitudinal wall of chamber 3.

The entire apparatus described above is housed in a housing 16 coated with shielding, for example made of lead, capable of providing protection in particular against ionizing radiation (a, ss, y rays) and electromagnetic waves.

This box 16 has, at one of its ends, two coaxial circular openings 17, 18 respectively formed on two opposite faces 19, 20 and connected to each other by a cylindrical tube 21.

This tube, inside which open the suction 22 and exhaust 23 orifices of the intake 14 and exhaust 9 circuits, is fitted with a turbine 24 actuated by a motor 25, this assembly being placed coaxially near opening 17.

Thanks to this arrangement, the turbine 24 generates, inside the tube, a forced air current of swirling nature which creates a "cyclone" effect tending to push the materials in suspension in the air (dust) towards the tube walls and to purify the air, near its longitudinal axis.

Thus, by centering the suction 22 and exhaust 23 orifices coaxially with the tube 21 and by orienting them in the opposite direction to the direction of air circulation, this eliminates the problem posed by dust.

The problem posed by the variations of pressure which reign at the level of the suction and exhaust orifices 22, 23, as a function of the amplitude and the orientation of the wind, is here resolved, thanks to the fact that one plans, next to

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 each of the two openings 17,18 of the tube 21, two respective disc-shaped deflectors 26, 27, which extend parallel to the walls 19 and 20 and which delimit, with these, two respective coaxial cylindrical openings 28,29 .

Thanks to such an arrangement, whatever its orientation, the action of the wind will be the same at the two openings 28, 29, and the air flow generated by the turbine 24 will not be able to reverse.

Consequently, the air pressure at the inlet of the intake and exhaust orifices 22, 23, which depends on the speed of circulation of the air flow generated by the turbine 24, will only be very slightly affected by variations in wind amplitude and orientation.

Advantageously, the relative axial positions and the sections of the intake and exhaust orifices 22, 23 will be provided so as to obtain, at these two orifices, a pressure difference promoting the circulation of the air inside. of the spectrophotometry device.

The problem relating to ionizing radiation possibly present in the places where the measurement is carried out is also resolved by using deflectors 26, 27 made of a material impervious to ionizing radiation (for example the material used for shielding) which form, with the shielding of the housing 16, baffles, making it impossible for any propagation of these radiations inside the housing 16.

In the example described above, the turbine 24, placed at the inlet 17 of the tube 21, delivers the air into the area where the intake and exhaust ports 22, 23 are located coaxially.

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Nevertheless, the turbine 24 could equip the outlet orifice of the nozzle (as shown in dashed lines) and perform a suction of the air coming from the latter.

In addition, it is possible to provide, between the intake and exhaust orifices 22, 23, an adjustable pressure-reducing element creating a reduction in the cross-section of the flow of air flow conveyed by the turbine 24.

This pressure-reducing element 30 in fact causes an increase in the pressure in the upstream zone Z 1 of the tube 2, containing the inlet orifice 22 and a decrease in the pressure in the downstream zone Z2 of the tube 21 containing the orifice of exhaust 23 (Venturi effect).

Due to the pressure difference obtained between the intake port 22 and the exhaust port 23, a spontaneous circulation of air is obtained inside the spectrophotometer which is added to or even can replace that generated by the turbine 10. Of course, in the latter case, the turbine 10 can be omitted.

In the example shown in Figure 3, the analysis device which is mounted on the front part of the vehicle roof comprises a tubular burner 31 comprising a tubular nozzle 32 connected on one side to a gas supply duct to be analyzed 33 and open on the other side and, coaxially with this nozzle 32: - a first tubular sleeve 34, of diameter slightly greater than that of the nozzle 32 and axially offset with respect to the latter, so as to delimit, from a on the one hand, with the nozzle 32, a first annular inlet chamber 35 connected to a circuit 36 for injecting hydrogen from a source 37 and, on the other hand, beyond the first nozzle 32, a chamber combustion 38 in which the partial combustion of the gas to be analyzed and of the hydrogen generates a first flame FI: this first

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tubular sleeve 34 closes on one side on the nozzle 32 and opens, on the other side, into a second combustion chamber 39; - A second tubular sleeve 40, of diameter greater than that of the first tubular sleeve 34 and delimiting therewith, a second annular inlet chamber 41 connected to an inlet circuit 42 of a gas or a gaseous mixture oxidant, for example air: this second sleeve 40 closes on one side on the nozzle 32 and / or on the first sleeve 34 and delimits, on the other side, beyond this, the second combustion chamber 39, in which a post-combustion takes place in an oxidizing medium of gases from the first combustion chamber 38 and the intake chamber 41; an annular electrode 44, of section substantially in the form of an inverted C, secured by its face of larger diameter 45 to the second sleeve 40, and of which the face of smaller diameter 46, which has an axial length shorter than that of the face 45, defines an outlet duct S from the combustion chamber 39: beyond the electrode 44 (on the side opposite to the sleeve 34), the sleeve 41 comprises a lateral orifice 47 into which an exhaust duct opens, provided with a turbine 48 powered by a motor; - a focusing optic 49 such as a lens mounted in the circular opening of a cover closing the sleeve 40, on the side opposite to the nozzle
32, this focusing optic 49 being designed so as to focus the light radiation emitted in the two combustion chambers 38, 39, in particular the first chamber 38, on the inlet orifice of a spectrophotometric assembly 50.

In this example, the tubular sleeve 34 is made of an electrically conductive material and constitutes a second electrode which cooperates with

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 the electrode 44 in order to allow the measurement of the conductivity of the area of the second chamber 39 in which the second flame develops (flame F2).

These two electrodes are electrically connected to resistance measurement means 51 which comprise a voltage source 52 connected in series with a voltmeter 53, this assembly being shunted by a resistance 54.

The information delivered by the spectrophotometric assembly 50 and by the voltmeter 53 is transmitted to a processor / display unit 55 programmed so as to determine the concentration of elements and / or substances sought in the gas sample supplied by the nozzle 32.

As previously mentioned, the outer surface of the sleeve 34 may be covered by a coating 56 of a material capable of emitting a reactive gas at the temperature at which this sleeve 34 is brought under the effect of the combustion generated in the first combustion chamber 38. By way of example, this reactive material could consist of Indium, the corresponding sought-after element then being chlorine.

In this case, the burner may include a third coaxial tubular sleeve 60 extending in the intermediate space between the sleeves 34 and 40. This third sleeve 60 defines with the sleeve 34 an annular chamber opening into the second combustion chamber 39 and serving for the admission into this chamber 39 of a stream of hydrogen coming from the source 37. To this end, the annular chamber 61 is connected to the source 37 by means of a controlled intake circuit 62 by a valve 63.

The operation of the previously described burner is then as follows:

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 The assembly of the two chambers 38, 39 is placed under vacuum by the turbine 48 so as to cause a suction of the gas to be taken from the nozzle 32, through a nozzle provided in the intake circuit 33.

Inside the sleeve 34, the flow of aspirated gas (for example air) mixes with the stream of hydrogen injected by the intake chamber 35, in a proportion such that the combustion produced in the first chamber combustion 38 is reducing. The light radiation generated by the flame FI present in the first chamber 38 makes it possible to detect, by means of the spectrophotometric arrangement 50, compounds such as phosphorus and sulfur and to deduce therefrom the presence of sought-after elements.

The temperature generated by this combustion causes the sleeve 34 and, consequently, the coating 56 to be heated.

When it reaches or exceeds its vaporization temperature, this coating 56 emits reactive vapor which mixes with the flow of hydrogen injected by the intake chamber 61 and with the air coming from the intake chamber 41.

Leaving these chambers 41 and 61, the gas mixture reacts (oxidative combustion) with the gas flow resulting from the partial combustion produced in chamber 38 to produce a flame F2 which emits light characteristic of a component such as chlorine which reacted with reactive Indium vapor. This light, like that produced in the chamber 38, is focused by the lens 49 at the entrance to the spectrophotometric assembly 50.

The information delivered by the assembly 50 as well as by the ammeter 53 (which are representative of the variations in conductivity of the flame (ionization) present in the second combustion chamber) are transmitted to the processor 55, which is programmed so as to interpret these

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 information and to deduce therefrom concentrations of sought-after elements, be it compounds, chemical substances or even biological substances (bacteria).

Of course, in the case where the gaseous sample to be analyzed contains suspended particles (for example bacteria or dust), these particles on burning generate light pulses ("flash") of limited duration that it is possible to count to obtain the number of particles per unit volume of gas to be analyzed.

In this example, the gas supply duct 33 to be analyzed comprises a transparent portion 65, for example made of glass or quartz, preferably of square or rectangular section so as to have two parallel plane faces 66,67.

The face 66 of this transparent portion is illuminated at normal incidence by a light source 68 oriented perpendicular to the flow path of the gas to be analyzed and therefore coaxially with the burner and the focusing optic 49.

Opposite the source 68, relative to the transparent portion, is arranged an optical sensor 69 connected to the processor 55. This optional sensor 69 is intended to perform a turbidimetric measurement of the gas flow.

Thanks to the particularities of the burner and due to its passage in the transparent portion 65, the gas flow is located in the axis of the focusing optic 49, the spectrophotometric assembly is used to perform a nephelometric measurement of this gas flow (detection of the light scattered by the particles present in the illuminated gas flow).

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 To this end, the wavelength of the radiation emitted by the source 68 is chosen (here in the near infrared) so as not to disturb the photometric measurement carried out by the assembly 50.

The nephelometric analysis gives an estimate of the light scattered by the particles present in the gas stream. It allows the determination, by means of measurements of variation of the quantity of light, of low concentrations of substances.

Turbidimetric analysis makes it possible to provide a more suitable measurement when the gas to be analyzed carries a large number of particles.

It is clear that the combination of these measurements makes it possible to determine parameters (size, weight, humidity, etc.) making it possible to classify the particles even before proceeding to their spectrophotometric analysis.

These two analyzes can possibly be supplemented by a fluorescence measurement. In this case, a light source operating in pulse mode is used.

Optionally, the spectrophotometric assembly associated with the burner could be designed to further perform fluorescence spectroscopy of the gas stream upstream of the burner.

Of course, the microprocessor 55 will have to be programmed so as to take advantage of the results of all these analyzes.

In particular, the microprocessor will be programmed so as to compose, following each of the analyzes, a message comprising the result of the analysis as well as:

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 - vehicle identification data previously stored, - time stamping data, - data relating to the geographical position of the point where the measurement was made; these data could advantageously be provided by a location system 70, for example of the GPS ("global positioning system") type connected to the microprocessor 55, - data concerning parameters relating to the point at which the measurement was made such as the temperature , pressure, wind speed and orientation, rain, etc.

Of course, in the case where the public transport network is a railroad or a metro, the data relating to the geographic position will be obtained by means of the devices usually fitted to railways and metros.

The messages composed by the microprocessor will be conformed and applied to the transmitter / receiver device 71 equipping the vehicle with a view to being in turn transmitted, for example by radio, to the transmitter / receiver of the central control station 72.

Optionally, the transmitter / receiver device 71 will be designed to receive control messages from the central station, for example with a view to repeating an analysis cycle or even increasing or reducing the frequency of the analysis cycles carried out by the analysis device, or even to modify its operating mode.

Claims (12)

claims 1. Method for detecting the presence in the atmosphere of chemical and / or biological substances, for the identification and quantification of these substances, for the location of the geographical extent of the area contaminated by said substances as well as for quantitative analysis by geographic vectors of the contamination as well as the evolution in time and space of this contamination, characterized in that it consists in equipping public transport vehicles (VI, V'l-V2 , V'2-V3, V'3) performing regular lines in the area to be monitored, analyzers capable of continuously detecting and analyzing air in very short times and transmitting, in time real, intended for the central command post (PC), messages comprising the result of the analysis which has just been made, time stamping data as well as geographical data relating to the place where the analysis was carried out, and in that the central station (PC) which receives the messages from all vehicles equipped with analyzers performs an analysis of these results so as to be able to know at all times all the useful information on a contamination including the nature, concentration, l extent and evolution in time and space.  2. Method according to claim 1, characterized in that the above geographic data are obtained by means of location normally fitted to vehicles.  3. Method according to claim 1, characterized in that the aforesaid geographical data are obtained by means of a reported location system (70).  4. Method according to claim 3, characterized in that the location system (70) is of GPS type. <Desc / Clms Page number 17>  5. Method according to one of the preceding claims, characterized in that it comprises the determination of variations over time and / or of the contamination gradients with determination of the core of the contamination.  6. Method according to one of the preceding claims, characterized in that the above detection and the above analysis are carried out by flame spectrophotometry.  7. Method according to one of the preceding claims, characterized in that it uses a spectrophotometric detection device and / or ionization, and in that the gas stream entering the device is illuminated by means of a light source (68) emitting in a range of wavelengths distinct from that used for spectrophotometry, in that a nephelometric and / or turbidimetric detection of the gas flow used is carried out, and in that one uses the information resulting from this detection to carry out an appropriate adjustment of the spectrophotometric apparatus, to carry out a counting of the particles present in the gas flow, and / or to deduce the composition of said particles from said information and from those delivered by the apparatus spectrophotometric.  8. Method according to claim 7, characterized in that it further comprises a measurement of the fluorescence of the gas stream illuminated by said source (68).  9. Method according to claim 7, characterized in that the above nephelometric measurement is ensured by the above spectrophotometric detection device. <Desc / Clms Page number 18>  10. System for implementing the method according to one of the preceding claims, characterized in that it involves: - at least one network of public transport vehicles (for example a railway, metro network , bus) using vehicles (Vj, V'j- V2, V'z - V3, V'3) each equipped with communication means (71) with a central control station (72) and location means (70), - at least one analysis device mounted on each vehicles (VI, V'i- V2, V'z - V3, V'3), this analysis device being designed so as to continuously carry out analyzes while the vehicle is moving, - means (55) making it possible to compose digital messages each containing the result of an analysis carried out by an analysis device, vehicle identification data, time stamping data as well as geographic location data of the place in which it was carried out analysis, - means for transmitting these messages to the central station (PC) via the above communication means (71), - means for analyzing, in real time, the messages received by the central station (PC) from vehicles so as to be able to present at all times to an operator all useful information occurring in a protected area.  11. System according to claim 10, characterized in that it comprises a transmitter / receiver device (71) for transmitting the above messages over the air. <Desc / Clms Page number 19>  12. System according to claim 11, characterized in that the aforesaid transmitter / receiver device (71) is designed to receive control messages from the central station (PC), and in that it comprises suitable control means to modify the operating mode of the analysis device.