JP2011252893A - On-vehicle environmental load gas measuring device and measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect environmental load gas with high sensitivity even in the place where there is no external power supply and while a vehicle is driving.SOLUTION: A battery box 20 and an environment measuring device 30 are mounted on a station wagon 10. The environment measuring device 30 is fixed inside the vehicle by one frame. It operates by power supplied from the battery 21 or the external power supply. In the environment measuring device 30, ultraviolet light 35 generated at a laser generating part 31 is converted into vacuum ultraviolet light 37 at a vacuum ultraviolet light generating part 33, and is introduced to an ionization part 38. Gas to be measured which is taken in at an atmosphere gas introducing part 50 is also introduced to the ionization part 38. The gas to be measured introduced to the ionization part 38 is ionized by the vacuum ultraviolet light 37 and mass spectra of an ion 73 is measured at a time-of-flight mass analyzing part 34.

Description

  The present invention relates to an apparatus and method for simultaneously ionizing a plurality of environmentally harmful gas component molecules contained in the atmosphere by irradiating a vacuum ultraviolet laser and measuring the environmentally harmful molecules in real time with a time-of-flight mass spectrometer. About.

In recent years, the release of environmentally hazardous gases into the atmosphere has become a major social problem, and laws and regulations including vehicle exhaust gas regulations are becoming stricter year by year. Countermeasures for environmental problems are an urgent issue, but in order to take effective countermeasures, it is important to accurately and quickly measure the component molecules of environmentally hazardous gases, and effective methods for that are required. ing.
In general, mass spectrometry (MS) is used for detection and identification of organic compounds for measuring component molecules of environmental burden in the atmosphere. In mass spectrometry, atoms, molecules, etc. are ionized by some method, ions are moved in a vacuum, ions are separated by mass-to-charge ratio (m / z) using electromagnetic force, and a mass spectrum is recorded. is there. Of these, gas chromatograph mass spectrometry (GC / MS) is generally used as a method for measuring organic compounds. The GC / MS method can detect component molecules of environmentally hazardous gases in the atmosphere with high sensitivity. However, since the GC / MS method requires a long time for measurement, it is difficult to quickly detect harmful molecules when they are generated. In addition, since the GC / MS apparatus is generally a stationary type, it is impossible to perform measurement while moving to a plurality of locations or measuring while moving.

  Therefore, in recent years, development of handy type gas analyzers such as semiconductor sensors, which can be measured in a short time and can be easily carried, has been actively conducted. However, such a handy-type gas analyzer such as a semiconductor sensor can detect only specific molecules, and it is difficult to identify unknown molecules. In addition, the detection sensitivity of such a handy type gas analyzer is limited to the ppm level. However, detection sensitivity at the ppb level is necessary to measure environmentally harmful molecules in the atmosphere. For this reason, it is difficult to say that such a handy-type gas analyzer has sufficient performance.

  Therefore, an in-vehicle device that can identify molecules that cannot be identified by a semiconductor sensor has also been developed. Patent Document 1 discloses a gas leak detection system using a vehicle-mounted gas sensor using a laser. However, in this gas leak detection system, the detection sensitivity is insufficient because the lower limit of the detection sensitivity is several tens of ppm. Patent Document 1 describes that driving power is supplied from a power socket. However, the amount of electricity supplied from the power socket is insufficient to start the device, and the operation is likely to be unstable. However, Patent Document 1 does not describe any countermeasures.

On the other hand, a method has been proposed in which a small GC / MS device is mounted on a vehicle to measure component molecules of environmentally hazardous gases. However, in this small GC / MS apparatus, it takes about 7 minutes for one measurement. For this reason, the component molecules of the environmentally hazardous gas cannot be measured in real time in units of seconds. In addition, this small GC / MS apparatus requires a power source for moving the apparatus. For this reason, there is a restriction that measurement can be performed only at a place where a power source can be secured.
Currently, as a method for measuring organic molecules in the atmosphere with high sensitivity, a method is generally used in which atmospheric gas is collected in a bag or the like and is measured using an apparatus provided in a laboratory. However, with this method, it is impossible to measure organic molecules in real time, and there is a problem such as a decrease in sensitivity due to the measurement molecules adsorbed on the bag.
As described above, the conventional analysis method must be said to have insufficient performance for measuring the component molecules of the environmentally hazardous gas. In particular, in order to have real-time measurement, it is possible to measure the generated molecules with high sensitivity without power supply from an external power source, even when the device is moved quickly to the measurement site or while running. Is required.

JP 2009-42965 A JP 2003-22777 A

N. Kanno and K. Tonokura, Appl. Spectrosc. 61, 896-902 (2007).

As described above, there is a demand for an effective measurement method for component molecules of environmentally harmful gases. In particular, the development of a measurement method that can achieve high sensitivity and real-time performance at low cost is an important issue.
In view of the above-mentioned problems of the prior art, the present invention is capable of quickly moving to a measurement place at low cost by self-running, and detecting environmental load gas with high sensitivity even in places where there is no external power source or while traveling. The purpose is to make it possible.

In order to solve the above-mentioned problem, the present inventor mounts an on-vehicle environmental load gas detection device in a specially modified vehicle, and has sensitivity (ppb order) equivalent to that of a general gas analyzer such as a GC / MS device, We have invented a device that can monitor trace organic molecules in the atmosphere while traveling.
That is, the first invention is
An in-vehicle environmental load gas measuring device that measures environmental load gas in the atmosphere in real time, an introduction mechanism for introducing air, an environmental measurement device for measuring the mass of component molecules of the environmental load gas, and the introduction mechanism A battery for supplying electric power to the environmental measuring device, and at least one frame for fixing the environmental measuring device in a vehicle, the measuring device generating a vacuum ultraviolet light generating unit for generating vacuum ultraviolet light, By irradiating the environmental load gas with vacuum ultraviolet light generated from the vacuum ultraviolet light generation unit, an ionization unit that ionizes component molecules of the environmental load gas, and a time-of-flight type that measures the mass number of the ionized molecules A vehicle-mounted environmental load gas measuring device comprising a mass spectrometer.
The second invention is
In order to prevent adsorption of molecules in the atmosphere, it further includes a heating mechanism that heats the introduction mechanism, and the introduction mechanism is configured such that the atmosphere is introduced from the atmosphere suction port, the introduced atmosphere is discharged from the pinhole, and the ionization unit A vehicle-mounted environmental load gas measuring device according to the first aspect of the present invention, further comprising: an introduction pipe to be introduced into the pump; and a pump for sucking air from the introduction pipe to the ionization unit.
The third invention is
The on-board environmental load gas measuring device according to the second aspect of the present invention is characterized in that the diameter of the pinhole is 10 μm to 20 μm.
The fourth invention is:
An environmental load gas measurement method using the on-vehicle environmental load gas measurement device according to the first aspect of the invention, the step of introducing the atmosphere from the introduction mechanism to the ionization unit, the step of generating the vacuum ultraviolet light, By irradiating the environmental load gas in the atmosphere with the vacuum ultraviolet light, the component molecules of the environmental load gas are ionized at once, and the time-of-flight mass analysis unit And a step of measuring a mass number.
The fifth invention is:
An environmental load gas measurement method using an on-vehicle environmental load gas measurement device according to a second aspect of the invention, wherein the introduction tube is heated by the heating mechanism to prevent the adsorption of molecules to the introduction tube A step of sucking into the introduction tube, a step of continuously introducing the air sucked into the introduction tube into the ionization section through the pinhole, a step of generating the vacuum ultraviolet light, and an environmental load in the atmosphere By irradiating the vacuum ultraviolet light to the gas, ionizing the component molecules of the environmental load gas collectively, and measuring the mass number of the component molecules of the environmental load gas by the time-of-flight mass spectrometer And a method for measuring an environmental load gas comprising the steps of:
The sixth invention is:
The environmental load gas measuring method according to the fourth or fifth aspect, wherein the environmental load gas in the atmosphere is measured in real time while traveling by car.

  According to the present invention, component molecules of environmentally harmful gases contained in the atmosphere can be measured with high sensitivity while running, so a wide range of environmentally harmful gas component molecules can be measured on-site in real time. It becomes possible. Compared to transporting a gas analyzer such as an ordinary GC / MS system to the measurement location and performing on-site real-time measurement, the transportation cost is about the same as gasoline, so it is overwhelming in terms of cost. Are better. In addition, the travel time to the measurement location is also greatly reduced because operations such as packing, moving, and installation of the apparatus are unnecessary.

It is a figure which shows typically an example of the schematic structure of the whole vehicle-mounted environmental load gas measuring apparatus. It is a figure which shows typically an example of schematic structure of a battery box. It is a figure which shows typically an example of schematic structure of an environmental measurement apparatus. It is a figure which shows typically an example of schematic structure of a vacuum ultraviolet light generation part. It is a figure which shows typically an example of schematic structure of an ionization part and a time-of-flight mass spectrometry part. It is a figure which shows typically an example of schematic structure of the atmospheric suction inlet vicinity of an atmospheric gas introduction part. It is a figure which shows typically an example of schematic structure of the whole atmospheric gas introduction part. It is a figure which shows the relationship between the density | concentration of benzene, toluene, and xylene measured at one measurement location around a chemical factory, and the elapsed time from a measurement start. It is a figure which shows the relationship between the density | concentration of benzene, toluene, and xylene measured while driving | running | working the periphery of a chemical factory for 5 minutes at 10 km / h, and the elapsed time from a measurement start.

FIG. 1 is a diagram schematically illustrating an example of the overall schematic configuration of an in-vehicle environmental load gas measuring device. In the present embodiment, the in-vehicle environmental load gas measuring device is installed in the one box car 10. FIG. 1A is a view of the inside of the one box car 10 as viewed from above, and FIG. 1B is a view of the inside of the one box car 10 as viewed from the side.
As shown in FIG. 1, the in-vehicle environmental load gas measuring device includes a battery box 20, an environmental measuring device 30, power cords 41 to 43, an atmospheric gas introduction unit 50, and a power connector 60.

FIG. 2 is a diagram schematically illustrating an example of a schematic configuration of the battery box 20. 2A is a diagram of the inside of the battery box 20 as viewed from above, and FIG. 2B is a diagram of the interior of the battery box 20 as viewed from the side.
In FIG. 2, the battery box 20 includes a battery 21, an inverter 22, a battery charger 23, a breaker 24, and support plates 25a and 25b.
The battery box 20 has nine batteries 21 including six AC100V batteries, one DC12V battery, and two DC24V batteries. There are two batteries under the battery 21a shown in FIG. As shown in FIG. 2B, the batteries 21b, 21c, and 21d are mounted on the support plate 25b.

The inverter 22 converts the DC power from the battery 21 into AC power, and outputs the AC power to the environment measuring device 30 via the power cord 41.
The battery box 20 includes a battery charger 23a for a 100V battery, a battery charger 23b for a 12V battery, and a battery charger 23c for a 24V battery. As shown in FIG. 2B, the battery chargers 23a, 23b, and 23c are attached on the support plate 25a.
At the time of charging, electric power is supplied from the power cord 42 to the battery charger 23 via the breaker 24, and the battery charger 23 charges the battery 21 having a voltage corresponding to itself. The electric power charged in the battery 21 is sent to the environmental measurement device 30, the data processing device, and the output / display device through the power cord 41 through the inverter 22 or directly without going through the inverter 22.

The environment measuring device 30 includes an intake unit for introducing atmospheric air (measuring target gas) containing trace organic molecules into the device, a laser generating unit, a mirror, a vacuum ultraviolet generating unit, an ionizing unit, a flight time, and the like. A mass spectrometer, all of which are fixed to the same frame. Further, in this embodiment, a data processing device that inputs a signal (ion signal) of a measurement target gas measured by the environment measuring device 30 and performs data processing, and an output / display device that displays the result of the data processing are also included in this frame. It is fixed to.
The frame is attached to the inside of the one box car 10. In addition, a buffer mechanism is provided between the bottom of the frame and the floor of the one box car 10 for suppressing damage to the apparatus during long distance traveling and rough road transportation. In this embodiment, the buffer mechanism has an aluminum plate, a polystyrene foam, and a rubber plate. Specifically, an aluminum plate is disposed under the bottom of the frame, a foamed polystyrene under the aluminum plate, a rubber plate under the foamed polystyrene, and a floor of the one box car 10 under the rubber plate.
The environment measuring device 30 includes a spot cooler and a dehumidifier for maintaining the environment of the device.

FIG. 3 is a diagram schematically illustrating an example of a schematic configuration of the environment measurement apparatus 30.
In FIG. 3, a laser generation unit 31, a mirror 32, a vacuum ultraviolet light generation unit 33, and a time-of-flight mass analysis unit 34 included in the environment measurement device 30 are illustrated.
In the present embodiment, a range of 100 nm to 150 nm can be used as the wavelength range of the vacuum ultraviolet light generated from the vacuum ultraviolet light generation unit 33. However, it is most preferable to use vacuum ultraviolet light having a wavelength of 118 nm because of the size and output of the apparatus.

FIG. 4 is a diagram (cross-sectional view) schematically illustrating an example of a schematic configuration of the vacuum ultraviolet light generation unit 33.
In FIG. 4, the vacuum ultraviolet light generator 33 includes a synthetic quartz lens 33a, an MgF ₂ lens 33b, a vacuum chamber 33c, and a Xe gas introduction pipe 33d.
The vacuum ultraviolet light generator 33 can be configured as follows in order to generate vacuum ultraviolet light having a wavelength of 118 nm. That is, ultraviolet light (ultraviolet laser light) 35 (third harmonic of Nd: YAG laser (355 nm)) generated (oscillated) by the laser generator 31 is placed in a gas cell filled with Xe gas 36 at an appropriate pressure. Then, the ultraviolet light 35 is converted into a third harmonic again at the focal point, and vacuum ultraviolet light (vacuum ultraviolet laser light) 37 having a wavelength of 118 nm is generated (oscillated). The pulse width of the Nd: YAG laser is preferably in the order of ns to fs, and the most preferable pulse width of the Nd: YAG laser is 5 ns. The larger the number of laser repetitions, the better. However, this number of repetitions depends on the number of repetitions of the ultraviolet laser that is the source of the generation of vacuum ultraviolet light. For this reason, when using a commercially available ultraviolet laser, the number of repetitions is generally 10 Hz to 30 Hz. According to the results of intensive studies by the present inventors, the number of repetitions is most preferably 20 Hz in terms of achieving both stability and sensitivity.

Here, when the ultraviolet light 35, which is the third harmonic of the Nd: YAG laser, is directly incident on the ionization portion, the measurement molecule is highly likely to be decomposed. As a countermeasure, the difference in refractive index between the ultraviolet light 35 and the vacuum ultraviolet light 37 is used to adjust the angle and position of the MgF ₂ lens 33b, which is a condensing lens, to separate the ultraviolet light 35. Thus, it is effective to design the optical system so that only the vacuum ultraviolet light 37 is incident on the ionization portion.
The relationship between the photon energy ε and the wavelength λ of the ultraviolet laser light is expressed by the following equation (1).
ε = hc / λ (1)
However, h is Planck's constant and c is the speed of light.
Therefore, when the ionization potential of a certain target molecule is IP, the photon energy ε is set so as to satisfy the following expressions (2) and (3).
IP <ε (2)
IP <hc / λ (3)
When these conditions are satisfied, the target molecule of interest can be ionized. That is, all molecules having an ionization potential lower than the photon energy of the vacuum ultraviolet laser can be detected all at once.

FIG. 5 is a diagram schematically illustrating an example of a schematic configuration of the ionization unit 38 and the time-of-flight mass analysis unit 34.
The ionization unit 38 and the time-of-flight mass analysis unit 34 are changed from atmospheric pressure to a vacuum state using, for example, a rotary pump and two turbo molecular pumps (manufactured by Pfeiffer Vacuum). In a state where the measurement target gas is not introduced, the degree of vacuum is preferably 1 × 10 ⁻⁴ Pa or less for the ionization unit 38 and 9 × 10 ⁻⁵ Pa or less for the time-of-flight mass analysis unit 34.
FIG. 6 is a diagram (cross-sectional view) schematically illustrating an example of a schematic configuration in the vicinity of the atmospheric suction port of the atmospheric gas introduction unit (introduction mechanism) 50.
The atmospheric suction port of the atmospheric gas introduction unit 50 is installed on the right rear side surface of the one box car 10, for example. The atmospheric gas introduction unit 50 has a pump that introduces the atmosphere introduced from the atmospheric suction port into the ionization unit 38. Even when a small pump with an exhaust speed of about 70 L / s is used as this pump, the atmospheric gas introduction unit 50 has a dust filter in order to introduce and measure the outside air as it is without being disturbed. In the collected gas to be measured, dust of 7 μm or more is removed with a dust filter, and the gas to be measured that has passed through the dust filter is an extremely small pinhole with a diameter of 10 μm to 20 μm. It is continuously introduced into the ionization section 38, which is a vacuum tank, from the port 50a. When the atmosphere is introduced from the atmospheric gas introduction unit 50 to the ionization unit 38, the ionization unit 38 has a vacuum degree of 1.2 × 10 ⁻¹ Pa or less, and the time-of-flight mass analysis unit 34 has a vacuum degree of 1.0 × 10 ⁻² Pa or less. The optimum degree of vacuum is 1.0 × 10 ⁻¹ Pa for the ionization unit 38 and 7.0 × 10 ⁻³ Pa for the time-of-flight mass analysis unit 34.

FIG. 7 is a diagram (cross-sectional view) schematically illustrating an example of a schematic configuration of the entire atmospheric gas introduction unit 50.
Vertical injection type that has a jet port that ejects gas between two plate electrodes, which are acceleration electrodes, and bends molecules ionized after being introduced from the jet port into the time-of-flight mass spectrometer by bending the plate at right angles There is an atmospheric gas introduction part. On the other hand, in the example shown in FIG. 7, the electrode itself described in Patent Document 2 also serves as an ejection port, and ionized molecules are introduced into the time-of-flight mass spectrometer unit coaxially with the ejection port without bending. The direct injection type atmospheric gas introduction part is shown. As the atmospheric gas introduction section, either the vertical introduction type or the direct injection type can be used.

As shown in FIG. 7, the direct injection type has a straight line so that the nose electrode 50b (the measurement gas discharge port 50a) and the ion drawing electrode 50c (the ion drawing port 50d) face each other. Be placed. For this reason, ionization efficiency and introduction efficiency of ions into the time-of-flight mass spectrometer 34 are high. Therefore, when it is necessary to measure the gas to be measured with high sensitivity, it is preferable to use the direct injection type atmospheric gas introduction unit 50. Here, there is also an apparatus described in Non-Patent Document 1 as a mass spectrometer using vacuum ultraviolet light. However, in Non-Patent Document 1, since the vertical introduction type atmospheric gas introduction unit is used, the measurement sensitivity of the measurement target gas is inferior to that of the direct injection type atmospheric gas introduction unit. Further, Non-Patent Document 1 does not include any description for mounting the environment measurement device on a vehicle.
On the other hand, in the measurement of the measurement target gas by the environment measurement apparatus of the present embodiment, adjustment of the measurement target gas is unnecessary, and sampling and measurement can be performed at any place where the measurement vehicle (one-box car 10) can enter. Is possible.

The measurement target gas 71 introduced into the ionization unit 38 from the measurement target gas ejection port 50 a of the nose electrode 50 b is photoionized at the ionization point 72 by being irradiated with the vacuum ultraviolet light 37 to become ions 73. The ions 73 enter the time-of-flight mass analyzer 34 while accelerating through the ion inlet 50d of the ion pull-in electrode 50c due to the potential difference between the nasal electrode 50b and the ion pull-in electrode 50c.
In FIG. 5, the time-of-flight mass analyzer 34 includes an MCP (multichannel plate) detector 34a and a reflectron 34b.
The ions 73 (ionized molecules) are folded by the reflectron 34b and detected by the MCP detection unit 34a, and a signal of the ions 73 is output as a current amount. A mass spectrum (mass number) is obtained by accelerating the ionized measurement target gas in a pulse manner and detecting a time difference until detection by the MCP detection unit 34a. That is, if the amount of charge received by the ions 73 is constant, a mass spectrum is obtained by utilizing the fact that the larger the mass-to-charge ratio, the slower the flight time.
The output / display device and the data processing device are configured using a preamplifier, a picometer, and a commercially available notebook personal computer (notebook PC). The signal of the ions 73 detected by the MCP detection unit 34a is amplified by a preamplifier (for example, VT120 manufactured by ortec), input to the notebook PC via the picometer, and a dedicated program installed in the notebook PC is executed. Is displayed and recorded. The signal of the ions 73 is averaged over a time frame of usually about 10 seconds. The program (dedicated program installed in the notebook PC) that the data processing device has is a dedicated program for gas measurement of this device, which can capture mass information of continuous gas every second, A mass spectrum every second is obtained. According to the results of intensive studies by the present inventors, the detection sensitivity of 2 ppb or less (S / N = 3) can be obtained with benzene by taking an average of 1 minute of the mass spectrum per second.

  When the measurement is performed while the environmental measurement device 30 is not fixed to a single frame, the fluctuation of the signal intensity of the ions 73 becomes large, the optical system goes wrong in about 10 minutes, and the measurement target gas cannot be measured. It was. Therefore, as a measure to protect the entire device from impact during travel, according to the results of intensive studies by the present inventors, a rubber sheet having a thickness of about 1.5 cm, a polystyrene foam material, aluminum The plates are arranged in order from the bottom, and these are fixed to the device base, and the environment measuring device 30 is guarded with a three-layer structure.

  Further, by fixing the main body of the environment measuring apparatus 30 to one frame, the structure of the entire apparatus can be moved even when vibration occurs, thereby preventing the positional relationship of the optical system included in the environment measuring apparatus 30 from being shifted. Measurement is possible while traveling. The frame used in this case is preferably made of stainless steel and has an integral rectangular parallelepiped frame structure, and the thickness of the frame is preferably 4 cm or more. The laser generator 31, the mirror 32, the vacuum ultraviolet light generator 33, the time-of-flight mass analyzer 34, and the ionizer 38 are firmly fixed to the frame with a special stainless steel jig.

Furthermore, it is preferable to fix at least four places of the frame with a band having a width of 4 cm or more and to fix the lower four corners and the upper four corners of the frame with the bands so that the frame does not move in the vehicle. It is. The battery box 20 is also fixed in the vehicle. The battery box 20 may be fixed together with the environmental measurement device 30 using a frame.
Even if the environment measuring device 30 needs to be adjusted due to optical system misalignment or device trouble, the environment measuring device 30 can be carried out of the vehicle by a caster attached to the environment measuring device 30. It is easy to adjust after moving to a wide area. When the road surface is good, it is possible to measure a wide range while traveling at a speed of 40 km / h, but from the viewpoint of maintaining measurement accuracy and preventing damage to the device, measurement while traveling The speed of the vehicle (one box car 10) when performing the vehicle is most preferably about 10km / h.

In order to lengthen the operation time of the apparatus by the battery 21, it is preferable to install a large number of batteries having a high capacity as much as possible according to the arrangement space in the vehicle. According to the results of intensive studies by the present inventors, as shown in FIG. 2, nine batteries (for example, lead storage battery manufactured by GS Yuasa), three battery chargers, one inverter, The battery can be driven for more than 3 hours depending on the configuration of the connector.
The power source from the battery 21 is preferably capable of using DC12V, DC24V and AC100V in order to enable stable operation without modifying the environmental measuring device 30. The DC 24V and DC 12V power supplies are supplied to the environmental measurement device 30 directly from the battery 21 or from the battery 21 via the connector section. AC100V power is obtained by converting DC24V into AC100V by the inverter 22, and this is supplied to the environment measuring device 30 via the connector. If the power connector 60 is provided on the exterior of the car (one box car 10) and wired to the battery box 20 in the car, the battery 21 can be charged with the battery 21 installed in the car.

  In addition, when the battery 21 having the specifications described above is mounted on the vehicle, the operating time with only the battery 21 is about 3 hours, but there may be a case where a longer measurement is required in a place where no power is supplied. In that case, first, the measurement vehicle is moved to a place where external power can be supplied, and an ionization unit that consumes the largest amount of power is used by using an external power source obtained via a power connector 60 provided on the exterior of the vehicle. 38 and the time-of-flight mass spectrometer 34 are put into an optimal vacuum state. Subsequently, by using an external power source, a part of the gas introduced from the atmosphere is sucked with a rotary pump to adjust the gas flow rate, and the degree of vacuum of the ionization unit 38 and the time-of-flight mass analysis unit 34 is set as described above. The process of adjusting to the optimum degree of vacuum is performed.

  Next, a step of switching to the battery mode is performed. When switching to battery mode, it is necessary to turn off the power once. The supply of power can be switched between the panel of the environmental measurement device 30 and the panel of the battery 21 (the power supply used by the environmental measurement device 30 can be switched from the external power supply to the battery 21). Therefore, the power supply can be switched in about 30 seconds. After switching the power supply, it recovers to the optimum state in about one minute. In this state, the external power supply is disconnected from the power supply connector 60, the measurement vehicle is moved to a measurement location where there is no external power supply, and measurement by battery drive is performed. As described above, by using an external power source in a process that consumes a large amount of power in the process performed by the environmental measurement device 30, a measurement time of 4.5 hours, which is 1.5 hours longer than when all processes are performed only by a battery, is secured. it can.

  When the outside air temperature is low, etc., the atmospheric gas introduction unit 50 (atmospheric intake port and introduction pipe) easily adsorbs high-boiling molecules such as naphthalene due to a decrease in temperature. For this reason, detection of high boiling point molecules may not be possible, or measurement sensitivity of high boiling point molecules may be reduced. Therefore, in order to introduce high-boiling molecules from the atmospheric gas introduction unit 50 into the environment measuring device 30 without loss, it is effective to heat the gas introduction path (introduction pipe) from the atmospheric inlet to the ionization unit 38 with a built-in heater. It is. The range of the heating temperature is 30 to 80 ° C., but the heating temperature is most preferably 60 ° C., in which the power consumption of the battery 21 does not become excessive, and molecules present in a gas state at normal temperature do not adsorb to the introduction tube. It is.

The battery 21 can be charged via a dedicated power cord (charging cable) 42 that connects a 100 V external power source to the power connector 60 and connects the battery 21 and the power connector 60 in the vehicle to each other. The current range of the external power supply during charging is 5 A to 30 A, but 15 A is most preferable. Also, a mechanism capable of switching between a circuit (power supply mode) from the battery 21 to the environmental measuring device 30 and a circuit (charge mode) from the external power supply to the battery 21 with a single switch is provided. Is desirable.
In addition, when the change in the wind is small and the influence of the exhaust gas of the measurement vehicle can be ignored, the measurement target gas can be measured while traveling, so the measurement vehicle is placed in the direction in which the strength of the measurement target gas (molecules) increases. The source of organic molecules can be clarified by moving it.

  As described above, in this embodiment, the battery box 20 and the environment measuring device 30 are mounted on the one-box car 10. The environment measuring device 30 is fixed in the vehicle by one frame. The environment measuring device 30 operates by receiving power from the battery 21 or an external power source. In the environment measuring device 30, the ultraviolet light 35 generated by the laser generator 31 is converted into vacuum ultraviolet light 37 by the vacuum ultraviolet light generator 33 and introduced into the ionization unit 38. The measurement target gas taken in by the atmospheric gas introduction unit 50 is also introduced into the ionization unit 38. The measurement target gas introduced into the ionization unit 38 is ionized by irradiation with vacuum ultraviolet light 37, and the time spectrum of mass analysis unit 34 measures the mass spectrum of the ions 73. As described above, since environmental load gas contained in the atmosphere can be measured with high sensitivity while running, it is possible to measure a wide range of environmental load gas in an on-site real time state. Compared to transporting a gas analyzer such as an ordinary GC / MS device to the measurement location and performing on-site real-time measurement, the transportation cost is less than the cost of gasoline. Can measure. In addition, the travel time to the measurement location is also greatly reduced because operations such as packing, moving, and installation of the apparatus are unnecessary. As described above, according to the present embodiment, the self-propelled vehicle can quickly move to a measurement place at low cost, and can detect environmental load gas with high sensitivity even in a place where there is no external power source or while traveling.

  Below, although the Example of an on-site real-time measurement by a vehicle-mounted environmental load gas detection apparatus is shown, this invention is not limited to an Example at all.

Example 1
<Battery drive>
In this example, the concentrations of benzene, toluene, and xylene contained in the atmosphere were measured by battery drive in a place where no power was supplied around the chemical factory. The on-vehicle environmental load gas detection device of the present embodiment is configured as disclosed in FIG. The measurement was performed by continuously introducing the atmosphere from the atmospheric suction port of the atmospheric gas introduction unit 50 by the above-described optimal method. FIG. 8 is a diagram showing the relationship between the concentration of benzene, toluene, and xylene measured at one measurement site around the chemical factory and the elapsed time from the start of measurement. As shown in FIG. 8, it was confirmed that the concentrations of benzene, toluene, and xylene fluctuated in a short time at this measurement location. Moreover, it was possible to measure continuously for 3 hours or more by battery drive.

(Example 2)
<Measurement sensitivity (detectable concentration)>
Using the apparatus and method of Example 1, 10 ppb standard gases of benzene, toluene, xylene and chlorobenzene were measured, and it was confirmed that any gas could be detected at S / N = 3 or more. In the case of benzene, toluene, and xylene, detection at S / N = 3 and 2 ppb or less was possible.

(Example 3)
<Measurement sensitivity during driving>
Using the apparatus of Example 1, pipes from 10 ppb standard gases of benzene, toluene, xylene and chlorobenzene were connected to the atmospheric suction port of the atmospheric gas introduction section 50, and these gases were run for 1 hour at 10 km / h. Was measured. As a result, it was found that the detection sensitivity during traveling of all the substances was the same constant value as that during non-traveling, and no error of the optical system due to travel occurred.
As described above, by using the in-vehicle environmental load gas detection device and the measurement method according to the present embodiment, the organic molecular components in the atmosphere can be simultaneously detected at high sensitivity, even in places where power is not supplied or while traveling. Can be measured.

(Comparative Example 1)
The vacuum ultraviolet generation unit 33, the ionization unit 38, and the time-of-flight mass analysis unit 34 were fixed to different frames, and measurements were performed while traveling in the same manner as in Example 3 except that. As a result, the optical system was distorted 1 minute after the start of running, and the signals of benzene, toluene, xylene and chlorobenzene could not be observed.

Example 4
<Measurement during driving>
In this example, environmental load gas around the chemical factory was monitored while traveling. Monitored are benzene, toluene and xylene. FIG. 9 is a diagram showing the relationship between the concentration of benzene, toluene and xylene and the elapsed time from the start of measurement, measured while traveling around the chemical factory at 10 km / h for 5 minutes. As shown in FIG. 9, it was possible to measure the occurrence of three types of molecules without shifting the optical system even while traveling.

  It should be noted that the embodiments and examples of the present invention described above are merely examples of implementation in practicing the present invention, and the technical scope of the present invention is interpreted in a limited manner by these. It must not be. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

10 One box car (measurement car)
20 Battery Box 21 Battery 22 Inverter 23 Battery Charger 24 Breaker 25 Support Plate 30 Environmental Measuring Device 31 Laser Generator 32 Mirror 33 Vacuum Ultraviolet Light Generator 34 Time-of-Flight Mass Spectrometer 35 Ultraviolet Light 36 Xe Gas 37 Vacuum Ultraviolet Light 38 Ionization 41-43 Power cord 50 Atmospheric gas inlet 60 Power connector

Claims (6)

An in-vehicle environmental impact gas measuring device that measures environmental impact gas in the air in real time,
An introduction mechanism for introducing the atmosphere;
An environmental measuring device for measuring the mass number of component molecules of the environmentally hazardous gas;
A battery for supplying power to the introduction mechanism and the environment measurement device;
And at least one frame for fixing the environment measuring device in the vehicle,
The measuring apparatus ionizes the component molecules of the environmental load gas by irradiating the environmental load gas with a vacuum ultraviolet light generation unit that generates vacuum ultraviolet light and the vacuum ultraviolet light generated from the vacuum ultraviolet light generation unit. A vehicle-mounted environmental load gas measuring apparatus comprising: an ionizing unit that performs measurement; and a time-of-flight mass analyzing unit that measures the mass number of the ionized molecule. A heating mechanism for heating the introduction mechanism to prevent adsorption of molecules in the atmosphere;
The introduction mechanism includes an introduction pipe that introduces air into the ionization unit through which air is introduced from an air suction port, discharges the introduced air from a pinhole, and a pump that sucks air from the introduction pipe to the ionization unit, The vehicle-mounted environmental load gas measuring device according to claim 1, wherein   The in-vehicle environmental load gas measuring device according to claim 2, wherein the pinhole has a diameter of 10 µm to 20 µm. An environmental load gas measuring method using the on-vehicle environmental load gas measuring device according to claim 1,
Introducing air from the introduction mechanism into the ionization unit;
Generating the vacuum ultraviolet light; and
Irradiating the environmentally harmful gas in the atmosphere with the vacuum ultraviolet light to ionize the component molecules of the environmentally harmful gas in a lump;
Measuring the mass number of the component molecules of the environmental load gas by the time-of-flight mass spectrometer. An environmental load gas measuring method using the on-vehicle environmental load gas measuring device according to claim 2,
Inhaling the atmosphere into the introduction tube while heating the introduction tube by the heating mechanism and preventing adsorption of molecules to the introduction tube;
Introducing the air sucked into the introduction tube continuously into the ionization section through the pinhole;
Generating the vacuum ultraviolet light; and
Irradiating the environmentally harmful gas in the atmosphere with the vacuum ultraviolet light to ionize the component molecules of the environmentally harmful gas in a lump;
Measuring the mass number of the component molecules of the environmental load gas by the time-of-flight mass spectrometer.   The environmental load gas measuring method according to claim 4 or 5, wherein the environmental load gas in the atmosphere is measured in real time while traveling by car.

Images