Opacity meter for monitoring exhaust emissions from non-stationary sources
First Claim
1. An opacity meter for measuring opacity of an exhaust plume emanating from a moving source of emissions, comprising:
- a) a light source transmitting a collimated beam of light located at a first measurement point, said point having a height, said light source further located on one side of a travel path of said moving source of emissions, said moving source emitting an exhaust plume, said light source for transmitting a collimated beam of light, said collimated light beam having an intensity, said collimated light beam further having an axis lying substantially across said travel path;
b) a light receiver means adapted to detect and measure said collimated light beam intensity, said light receiver means located at a second measurement point lying on a side opposite said one side of said travel path, said second point having a height substantially the same as said first point height, said light receiver means having an axis, said collimated light beam and said light receiver means in coaxial alignment defining an open light path, said height of said first and second measurement points chosen to locate said light path above said moving source such that said exhaust plume will pass through said collimated light beam; and
c) means for activating said light source such that said collimated light beam is received by said light receiver means prior to arrival of said moving source between said first and second measurement points.
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Accused Products
Abstract
Method and apparatus for determining the opacity of exhaust plumes from moving emissions sources. In operation, a light source is activated at a time prior to the arrival of a diesel locomotive at a measurement point, by means of a track trigger switch or the Automatic Equipment Identification system, such that the opacity measurement is synchronized with the passage of an exhaust plume past the measurement point. A beam of light from the light source passes through the exhaust plume of the locomotive and is detected by a suitable detector, preferably a high-rate photodiode. The light beam is well-collimated and is preferably monochromatic, permitting the use of a narrowband pass filter to discriminate against background light. In order to span a double railroad track and provide a beam which is substantially stronger than background, the light source, preferably a diode laser, must provide a locally intense beam. A high intensity light source is also desirable in order to increase accuracy at the high sampling rates required. Also included is a computer control system useful for data acquisition, manipulation, storage and transmission of opacity data and the identification of the associated diesel engine to a central data collection center.
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Citations
19 Claims
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1. An opacity meter for measuring opacity of an exhaust plume emanating from a moving source of emissions, comprising:
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a) a light source transmitting a collimated beam of light located at a first measurement point, said point having a height, said light source further located on one side of a travel path of said moving source of emissions, said moving source emitting an exhaust plume, said light source for transmitting a collimated beam of light, said collimated light beam having an intensity, said collimated light beam further having an axis lying substantially across said travel path; b) a light receiver means adapted to detect and measure said collimated light beam intensity, said light receiver means located at a second measurement point lying on a side opposite said one side of said travel path, said second point having a height substantially the same as said first point height, said light receiver means having an axis, said collimated light beam and said light receiver means in coaxial alignment defining an open light path, said height of said first and second measurement points chosen to locate said light path above said moving source such that said exhaust plume will pass through said collimated light beam; and c) means for activating said light source such that said collimated light beam is received by said light receiver means prior to arrival of said moving source between said first and second measurement points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for determining the opacity of an exhaust plume emitted from a moving source of emissions, comprising the steps of:
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a) opening a shutter means prior to the arrival of said moving source of emissions, detecting a background light intensity by a light detecting means, said detecting means generating a response signal in proportion to said detected light intensity, designating said signal response generated by said background light intensity as a first signal response; b) activating a light source, said light source emitting a collimated light beam, centering said collimated light beam onto said light detecting means by a lens means, detecting an unobscured intensity of said collimated light beam by said light detecting means, designating said light detecting means signal response generated by said unobscured intensity as a second signal response; c) detecting the change in said collimated light beam intensity, by said light detecting means, as said collimated light beam is partially blocked by said exhaust plume, designating said light detecting means signal response generated by the greatest detected intensity change as a third signal response; and d) determining an opacity of said exhaust plume by calculating a quantity equal to said second response signal less said thrid response signal divided by a quantity equal to said second response signal less said first response signal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification