Remote gas analyzer for motor vehicle exhaust emissions surveillance

• US 4,924,095 A
• Filed: 11/23/1988
• Issued: 05/08/1990
• Est. Priority Date: 06/02/1987
• Status: Expired due to Term

• Current Assignee: West Lodge Research A CA Partnership of Caleb V Swanson Jr and Joanne M Swanson
• Original Assignee: West Lodge Research
• Inventors: Swanson, Caleb V. Jr.
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): Hanig, Richard
• Application Number:
  US07/275,391
• Time in Patent Office: 531 Days
• Field of Search: 250/338.5, 250/338.1, 250/340, 250/341, 250/349, 250/345, 356/438, 73/116
• US Class Current: 250/338.5
• CPC Class Codes: G01N 2021/0314 Double pass, autocollimated path
• CPC Class Codes: G01N 2021/178 Methods for obtaining spatial resolution of the property being measured
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 2021/3513 Open path with an instrumental source
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis

Abstract

A remote gas analyzer for motor vehicle exhaust emission surveillance in which a planar array of gas analyzer beams intersects substantially an entire cross-sectional segment of an exhaust gas plume in order to determine the volume concentration of gas pollutants in the exhaust. In a further variation using more readily available equipment to detect the less prevalent pollutants, the planar array determines the change in amount per unit volume of a first pollutant emitted by a motor vehicle passing the array. The first pollutant having a relatively high and more easily detectable concentration. A second, multi-spectral gas analyzer beam intersects the exhaust to determine the change in concentration of the less prevalent pollutants with respect to ambient, and also determines the change in concentration of the first pollutant. The ratio of the change in the first pollutant'"'"'s weight per unit volume to its change in concentration as determined by the second analyzer is used to determine the change in the amount per unit volume of the remaining pollutants.

Claims

1. An apparatus for determining the amount of pollutants in the exhaust emitted from a moving motor vehicle traveling along a path, comprising:

a first array of emitters and detectors suitable for use in absorption spectroscopy positioned so the beams emitted by said emitters traverse said path down which said motor vehicle passes, said emitters and detectors positioned so that beams emitted by said emitters intersect substantially an entire cross-sectional area of said exhaust plume along a predetermined length of said exhaust plume, before said beams are received by said detectors, said first array detecting a first pollutant;

a second gas analyzer emitter and detector suitable for use in absorption spectroscopy orientated so that a second beam emitted by said second emitter passes adjacent said motor vehicle, the second beam intersecting the exhaust plume as it mixes with the atmosphere along a path length sufficient to allow determination of the increase in concentration of a plurality of pollutants emitted by said exhaust plume relative to the concentration before the exhaust from said motor vehicle intersected said second beam, said plurality of pollutants including said first pollutant;

a computer in communication with said first array of emitters and detectors to determine the relative increase in the amount per unit volume of said first predetermined pollutant contained in that portion of said exhaust plume intersected by said array, said relative increase being determined with respect to the amount of said first pollutant before said exhaust from said motor vehicle intersected the beams emitted by said first array, said computer further determining the relative increase in the amount per unit volume of said plurality of gases other than said first pollutant by using the ratio of said relative increased amount of said first pollutant to said relative increased concentration of said first pollutant from said second gas analyzer, multiplied by the relative increase in the concentration of each of said plurality of gases as determined from said second gas analyzer.

2. An apparatus as defined in claim 1, further comprising:

means for determining the velocity of said motor vehicle as it passes said first array, and wherein said computer uses said velocity to determine the amount of said pollutants per unit of distance traveled.

3. An apparatus as defined in claim 2, further comprising:

means for enclosing said first array, said second gas analyzer and said motor vehicle exhaust to inhibit environmental disturbances from dispersing said motor vehicle exhaust sufficiently to adversely inhibit the measurement of the amount and concentration of said exhaust gas constituents.

4. An apparatus as defined in claim 2, wherein said emitters emit infrared light.

5. An apparatus as defined in claim 2, wherein said array is a planar array.

6. An apparatus as defined in claim 3, wherein said emitters emit infrared light.

7. An apparatus as defined in claim 2, wherein said first array of emitters and detectors are oriented in planes substantially parallel to the path on which said motor vehicle is traveling.

8. An apparatus as defined in claim 2, wherein said first array of emitters and detectors are oriented in planes substantially perpendicular to the path on which said motor vehicle is traveling.

9. An apparatus as defined in claim 3, wherein said first array of emitters and detectors are oriented in planes substantially parallel to the path on which said motor vehicle is traveling.

10. An apparatus as defined in claim 3, wherein said first array of emitters and detectors are oriented in planes substantially perpendicular to the path on which said motor vehicle is traveling.

11. An apparatus as defined in claim 2, further comprising:

a second array of emitters and detectors suitable for use in absorption spectroscopy positioned substantially perpendicular to the orientation of said first array, said second array of emitters and detectors positioned so that beams emitted by said second array of emitters intersect substantially an entire cross-sectional area of said exhaust plume along a predetermined length of said exhaust plume, before said beams are received by said second array of detectors, and further intersect a substantial portion of the beams produced from said first array of emitters and detectors, said second array detecting the amount of said first pollutant so that said computer can more accurately determine the amount of said first pollutant.

12. An apparatus as defined in claim 3, further comprising:

a second array of emitters and detectors suitable for use in absorption spectroscopy positioned substantially perpendicular to the orientation of said first array, said second array of emitters and detectors positioned so that beams emitted by said second array of emitters intersect substantially an entire cross-sectional area of said exhaust plume along a predetermined length of said exhaust plume, before said beams are received by said second array of detectors, and further intersect a substantial portion of the beams produced from said first array of emitters and detectors, said second array detecting the amount of said first pollutant so that said computer can more accurately determine the amount of said first pollutant.

13. A method of determining pollutants in an exhaust plume of a motor vehicle moving along a road, comprising the steps of:

passing a first array of gas analyzer beams along a first beam path through a predetermined space across said motor vehicle path so that said exhaust plume generated by said motor vehicle passes through said predetermined space, said first array of beams being positioned such that substantially an entire cross-sectional segment of said exhaust plume is intersected by said first array of beams along a predetermined length of said exhaust plume;

measured the ambient amount of a first pollutant contained in said predetermined volume of space in a first measurement, and measuring the amount of said first pollutant in said predetermined volume after a motor vehicle exhaust has passed through said first array in a second measurement, said first and second measurements being performed by the use of said first array of beams;

passing a second, multi-spectral gas analyzer beam along a second beam path adjacent said motor vehicle, said second beam path having sufficient length to allow a determination of the change in concentration of a plurality of pollutants from said exhaust plume intersecting beam second path relative to the concentration of said plurality of pollutants before said motor vehicle began to traverse said road, said plurality of pollutants including said first pollutant;

measuring the ambient concentration of said plurality of pollutants in said exhaust plume intersecting said beam path of said second gas analyzer beam in a third measurement, said third measurement including the concentration of said first pollutant, and in a fourth measurement - measuring the concentration of said plurality of pollutants after said motor vehicle exhaust has passed through said second beam, said third and fourth measurements using said second gas analyzer beam;

calculating a ratio by determining the relative increase in the amount of said first pollutant in the predetermined volume by use of said first and second measurements, and dividing that relative increase by the relative increase in the concentration of said first pollutant as determined from said third and fourth measurements;

determining the relative increase in the amount per unit volume of said plurality of pollutants other than said first pollutant by using said ratio and said third and fourth concentration measurements for said plurality of gases.

14. A method as defined in claim 13, wherein the weight of pollutants per unit volume is determined for said plurality of pollutants.

15. A method as defined in claim 13, further comprising the step of:

measuring the velocity of said motor vehicle as it passes said predetermined space of said first array, and using said velocity to determine the amount of said pollutants per unit of distance traveled.

16. A method as defined in claim 13, further comprising the step of:

temporarily enclosing said exhaust from said motor vehicle in a tunnel during said second and fourth measurements.

17. A method as defined in claim 16, further comprising the steps of:

passing a second array of gas analyzer beams along a second beam path through a predetermined space across said motor vehicle path so that said exhaust plume generated by said motor vehicle passes through said predetermined space, said second array of beams being positioned such that substantially an entire cross-sectional segment of said exhaust plume is intersected by said second array of beams along a predetermined length of said exhaust plume, said second array of beams being at an angle to, and intersecting a substantial portion of, said first array of beams; and

using said second array of beams to take additional measurements concerning the relative change in the amount of said first pollutant contained in said predetermined volume of space before said motor vehicle began to traverse said road, and after said motor vehicle began to traverse said road, and using said additional measurements to determine the amount of pollutants per unit volume for said plurality of pollutants.

18. A method as defined in claim 16, further comprising the steps of:

enclosing said exhaust plume intersected by said first and second arrays and intersected by said second gas analyzer beam, to inhibit environmental disturbance of said exhaust plume.

19. A method as defined in claim 13, further comprising the step of:

temporarily enclosing said exhaust from said motor vehicle in a tunnel during said measuring steps.

20. A method of determining pollutants in an exhaust plume of a motor vehicle moving along a road, comprising the steps of:

passing a first array of gas analyzer beams along a first beam path through a predetermined space across said motor vehicle path so that said exhaust plume generated by said motor vehicle passes through said predetermined space, said first array of beams being positioned such that substantially an entire cross-sectional segment of said exhaust plume is intersected by said first array of beams;

measuring the increase in the amount of a first pollutant contained in a predetermined volume of space relative to the amount of said first pollutant after a motor vehicle exhaust has passed through said first array, using said first array of beams and further measuring the percentage increase of said first pollutant;

passing a second, multi-spectral gas analyzer beam along a second beam path adjacent said motor vehicle, said second beam path having sufficient length to allow a determination of the change in concentration of a plurality of pollutants in said exhaust plume along said beam path relative to the concentration before said motor vehicle began to traverse said road, said plurality of pollutants including said first pollutant;

measuring the change in concentration of said plurality of pollutants of said exhaust plume which intersect said beam path of said second gas analyzer beam, relative to the concentration when said motor vehicle began to traverse said road, using said second gas analyzer beam;

determining the ratio of the relative increase determined from said first array, to the relative increase of said first pollutant from said second beam, and using that ratio with the relative change in concentration of said plurality of gases from said second gas analyzer beam to determine the relative increase in the amount per unit volume of said plurality of pollutants other than said first pollutant.

21. The method as defined in claim 20, comprising the further step of:

measuring the velocity of said motor vehicle as it passes said predetermined space of said first array, and using said velocity to determine the amount of said pollutants per unit of distance traveled.