Backscatter instrument for monitoring particulate levels in a gas stream
OwnerThomas H. Roseinventor
Life of this patent
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Abstract
An automatic setup backscatter particulate monitor includes a small source (38) of narrow beam radiant energy directed into a gas stream containing particulates. A lens (34) that is mounted behind the radiant energy source (38) collects the energy reflected back from the particulates and concentrates it on a photodetector (48). The beam is directed into duct at an angle greater than twice the beam spread, minimizing reflection off opposing wall surfaces. Internal radiant energy sources are periodically directed to the detector to verify system integrity. Backscattered energy is corrected for energy reflected from the opposite stack wall and for ambient energy.
Claims20
A backscatter instrument for monitoring the level of particulates in a gas stream flowing through a stack or duct, said backscatter instrument comprising:
- a radiant energy source for delivering a narrow beam of radiant energy across the stack or duct through an opening in the stack or duct wall;
- a lens positioned behind the radiant energy source for receiving radiant energy backscattered from particulates in the stack or duct and focusing the radiant energy at a focal point;
- the radiant energy source being positioned on the lens;
- a photodetector sensitive to the band of radiant energy emitted by the radiant energy source, said photodetector being located at or near the focal point of the lens;
- means responsive to the radiant energy incident on the photodetector for generating a signal representative of the intensity of incident radiant energy;
- and
- signal processing means for providing the facility operator with an indication of the particulate level in the gas stream.
A method of monitoring dust levels in a stack or duct associated with a baghouse-type pollution control installation wherein the stack or duct has a diameter of less than about five feet and the fluid stream in said stack or duct, in normal operation, has an opacity less than about 5%, said method comprising the steps of:
- establishing a narrow beam of radiant energy across the stack or duct;
- receiving backscattered radiant energy on a single lens having a focal point, the lens being positioned behind the radiant energy source and secured thereto;
- detecting the intensity of the backscattered radiant energy at or near the lens focal point;
- generating a signal representative of the intensity of the radiant energy at the lens local point;
- and
- providing the system operator with an indication of the particulate level in the gas stream.
A backscatter instrument for monitoring the level of particulates in a gas stream flowing through a stack or duct, said backscatter instrument comprising:
- a radiant energy source for delivering a narrow beam of radiant energy across the stack or duct;
- a lens positioned behind the radiant energy source for receiving radiant energy backscattered from particulates in the stack or duct and focusing the radiant energy at a focal point;
- the radiant energy source being positioned on the lens;
- and
- a photodetector located at or near the focal point of the lens.
Dependencies are inferred from the claim text.